Subjects -> MINES AND MINING INDUSTRY (Total: 82 journals)
Showing 1 - 42 of 42 Journals sorted alphabetically
American Mineralogist     Hybrid Journal   (Followers: 16)
Applied Earth Science : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 4)
Archives of Mining Sciences     Open Access   (Followers: 3)
AusiMM Bulletin     Full-text available via subscription   (Followers: 1)
BHM Berg- und Hüttenmännische Monatshefte     Hybrid Journal   (Followers: 2)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
CIM Journal     Hybrid Journal  
Clay Minerals     Hybrid Journal   (Followers: 9)
Clays and Clay Minerals     Hybrid Journal   (Followers: 5)
Coal Science and Technology     Full-text available via subscription   (Followers: 4)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 14)
Environmental Geochemistry and Health     Hybrid Journal   (Followers: 3)
European Journal of Mineralogy     Hybrid Journal   (Followers: 14)
Exploration and Mining Geology     Full-text available via subscription   (Followers: 3)
Extractive Industries and Society     Hybrid Journal   (Followers: 2)
Gems & Gemology     Full-text available via subscription   (Followers: 2)
Geology of Ore Deposits     Hybrid Journal   (Followers: 5)
Geomaterials     Open Access   (Followers: 3)
Geotechnical and Geological Engineering     Hybrid Journal   (Followers: 9)
Ghana Mining Journal     Full-text available via subscription   (Followers: 3)
Gold Bulletin     Hybrid Journal   (Followers: 2)
Inside Mining     Full-text available via subscription  
International Journal of Coal Geology     Hybrid Journal   (Followers: 4)
International Journal of Coal Preparation and Utilization     Hybrid Journal   (Followers: 2)
International Journal of Coal Science & Technology     Open Access   (Followers: 1)
International Journal of Hospitality & Tourism Administration     Hybrid Journal   (Followers: 16)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 12)
International Journal of Mining and Geo-Engineering     Open Access   (Followers: 4)
International Journal of Mining and Mineral Engineering     Hybrid Journal   (Followers: 8)
International Journal of Mining Engineering and Mineral Processing     Open Access   (Followers: 6)
International Journal of Mining Science and Technology     Open Access   (Followers: 4)
International Journal of Mining, Reclamation and Environment     Hybrid Journal   (Followers: 6)
International Journal of Rock Mechanics and Mining Sciences     Hybrid Journal   (Followers: 9)
Journal of Analytical and Numerical Methods in Mining Engineering     Open Access  
Journal of Applied Geophysics     Hybrid Journal   (Followers: 18)
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of China Coal Society     Open Access  
Journal of China University of Mining and Technology     Full-text available via subscription   (Followers: 1)
Journal of Convention & Event Tourism     Hybrid Journal   (Followers: 6)
Journal of Geology and Mining Research     Open Access   (Followers: 10)
Journal of Human Resources in Hospitality & Tourism     Hybrid Journal   (Followers: 9)
Journal of Materials Research and Technology     Open Access   (Followers: 2)
Journal of Metamorphic Geology     Hybrid Journal   (Followers: 17)
Journal of Mining Institute     Open Access  
Journal of Mining Science     Hybrid Journal   (Followers: 5)
Journal of Quality Assurance in Hospitality & Tourism     Hybrid Journal   (Followers: 6)
Journal of Sustainable Mining     Open Access   (Followers: 3)
Journal of the Southern African Institute of Mining and Metallurgy     Open Access   (Followers: 6)
Lithology and Mineral Resources     Hybrid Journal   (Followers: 4)
Lithos     Hybrid Journal   (Followers: 11)
Mine Water and the Environment     Hybrid Journal   (Followers: 6)
Mineral Economics     Hybrid Journal   (Followers: 2)
Mineral Processing and Extractive Metallurgy : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 14)
Mineral Processing and Extractive Metallurgy Review     Hybrid Journal   (Followers: 5)
Mineralium Deposita     Hybrid Journal   (Followers: 4)
Mineralogia     Open Access   (Followers: 2)
Mineralogical Magazine     Hybrid Journal   (Followers: 1)
Mineralogy and Petrology     Hybrid Journal   (Followers: 5)
Minerals     Open Access   (Followers: 2)
Minerals & Energy - Raw Materials Report     Hybrid Journal   (Followers: 1)
Minerals Engineering     Hybrid Journal   (Followers: 14)
Mining Engineering     Full-text available via subscription   (Followers: 7)
Mining Journal     Full-text available via subscription   (Followers: 4)
Mining Report     Hybrid Journal   (Followers: 3)
Mining Technology : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 4)
Mining, Metallurgy & Exploration     Hybrid Journal  
Natural Resources & Engineering     Hybrid Journal  
Natural Resources Research     Hybrid Journal   (Followers: 5)
Neues Jahrbuch für Mineralogie - Abhandlungen     Full-text available via subscription   (Followers: 1)
Physics and Chemistry of Minerals     Hybrid Journal   (Followers: 4)
Podzemni Radovi     Open Access  
Rangeland Journal     Hybrid Journal   (Followers: 4)
Réalités industrielles     Full-text available via subscription  
Rem : Revista Escola de Minas     Open Access  
Resources Policy     Hybrid Journal   (Followers: 4)
Reviews in Mineralogy and Geochemistry     Hybrid Journal   (Followers: 5)
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Rock Mechanics and Rock Engineering     Hybrid Journal   (Followers: 9)
Rocks & Minerals     Hybrid Journal   (Followers: 5)
Rudarsko-geološko-naftni Zbornik     Open Access  
Transactions of Nonferrous Metals Society of China     Hybrid Journal   (Followers: 9)
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Journal Cover
Journal of Materials Research and Technology
Journal Prestige (SJR): 0.957
Citation Impact (citeScore): 4
Number of Followers: 2  

  This is an Open Access Journal Open Access journal
ISSN (Print) 2238-7854
Published by Elsevier Homepage  [3304 journals]
  • Neural network modeling for anisotropic mechanical properties and work
           hardening behavior of Inconel 718 alloy at elevated temperatures

    • Abstract: Publication date: Available online 19 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Gauri Mahalle, Omkar Salunke, Nitin Kotkunde, Amit Kumar Gupta, Swadesh Kumar Singh Inconel alloys are gaining a special attention for high temperature applications in service environment of aircraft structures, rocket engines, nuclear reactors, gas turbines and pressure vessels. This makes crucial to understand anisotropic material properties and work hardening behavior of a material. In this study, various mechanical properties such as ultimate strength σuts, yield strength σys, strain hardening exponent (n) and % elongation have been evaluated by using uniaxial tensile tests. The tensile tests have been conducted from room temperature to 600°C at an interval of 100°C with different slow strain rates (0.0001, 0.001, 0.01 s−1). Additionally, anisotropy of Inconel 718 alloy has been evaluated based on various measurable parameters such as normal anisotropy, planer anisotropy, in-plane anisotropy and anisotropic index. Furthermore, stress–strain response is analyzed by empirical work hardening equation by Hollomon, Swift, Ludwick and Voce. The Artificial Neural Network (ANN) models have been developed to predict various anisotropic mechanical properties and hardening behavior of Inconel 718 alloy. The ANN model is skilled by Levenberg–Marquardt algorithm and signifies a good accuracy of model with an excellent correlation coefficient and significantly low average absolute error. Validation for the accuracy of developed ANN model is confirmed with results from f-test and mean paired t-test.
       
  • The effect of copper addition on the corrosion resistance of cast duplex
           stainless steel

    • Abstract: Publication date: Available online 18 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Hillane Mirelle Lopes Ferreira de Lima, Sérgio Souto Maior Tavares, Marcelo Martins, Walney Silva Araújo In this study, the effects of the addition of 3.01% Cu on the corrosion behaviour of cast duplex stainless steel aged for 1 h at different temperatures between 450 and 600 °C was investigated by electrochemical tests in 0.6 M NaCl, 0.3 M H2SO4 and 0.6 M NaCl + 0.3 M H2SO4. A short ageing time increases the hardness and mechanical resistance of the Cu-containing steel by precipitation hardening. Potentiodynamic polarization and electrochemical impedance spectroscopy results show that the effect of Cu addition depends on the media studied. In addition, critical pitting temperature (CPT) measurements revealed that steel with 3.01% Cu has a lower pitting corrosion resistance. On the other hand, for both steels, the short time ageing caused a slight increase in CPT values.
       
  • Phase separation and enhanced wear resistance of Cu88Fe12 immiscible
           coating prepared by laser cladding

    • Abstract: Publication date: Available online 18 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Shuzhen Zhao, Shengfeng Zhou, Min Xie, Xiaoqin Dai, Dongchu Chen, Lai-Chang Zhang In order to eliminate the microstructure segregation of Cu–Fe immiscible alloys which characterized with a liquid miscible gap, the Cu88Fe12 (wt.%) immiscible coating was prepared by laser cladding. The phase separation characteristic and wear resistance of the Cu88Fe12 (wt.%) immiscible coating were also investigated. The results show that the size of the milled Cu88Fe12 composite powder is reduced comparing to that of the un-milled powder due to fracturing during mechanical milling. Moreover, the demixing or delamination disappears in the Cu88Fe12 immiscible coating and a large amount of face-centered-cubic (fcc) γ-Fe and body-centered-cubic (bcc) α-Fe particles are dispersed in the face-centered-cubic (fcc) ɛ-Cu matrix as a result of liquid phase separation. The size of Fe-rich particles presents an increasing tendency from the bottom to the top of the immiscible coating. As a result, the microhardness of the immiscible coating is improved compared with brass (∼138 HV0.2) due to the presence of high-hardness Fe-rich particles (∼191 HV0.2) and the solid solution strengthening effect of Fe in Cu-rich matrix. Furthermore, the width of ploughing, the width and height of wear scar on the surface of the immiscible coating are much less than those on the surface of brass. Therefore, the wear resistance of the immiscible coating is remarkably enhanced compared with brass.
       
  • Effect of high-temperature degradation on microstructure evolution and
           mechanical properties of austenitic heat-resistant steel

    • Abstract: Publication date: Available online 18 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Jaegu Choi, Chang-Sung Seok, Soo Park, Gayeon Kim 21-4N austenitic heat-resistant steel is widely used as the material for automobile engine valves because of its high strength, excellent creep resistance, oxidation resistance and corrosion resistance under high-temperature circumstances. Engine valves, which are exposed to high temperatures for long periods, undergo material degradation in which the initial microstructure of the material is changed, resulting in deterioration of mechanical properties. This degradation can cause valve failure. Therefore, the microstructure and mechanical characteristics of degraded valves are important issues in designing the hot-section engine components. In this study, the changes in the microstructure evolution and mechanical properties of 21-4N austenitic steel were investigated after exposure at high temperature (1123 K) for 10–200 h, using accelerated degradation testing. To evaluate the degradation characteristics of 21-4N austenitic heat-resistant steel, we analyzed the microstructure evolution (e.g., grains, surface oxides, carbides, and phase) and the change in mechanical properties (e.g., tensile strength and, hardness) for virgin and degraded specimens. Finally, analyses and tests results demonstrate the correlation between microstructure evolution and changes in mechanical properties.
       
  • Microstructure and mechanical behavior of Al92Fe3Cr2X3 (X = Ce, Mn, Ti,
           and V) alloys processed by centrifugal force casting

    • Abstract: Publication date: Available online 18 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Guilherme Yuuki Koga, Ana Martha Branquinho e Silva, Witor Wolf, Claudio Shyinti Kiminami, Claudemiro Bolfarini, Walter José Botta Microstructural and mechanical characterization of Al92Fe3Cr2X3 (X = Ce, Mn, Ti, and V) alloys were performed. The alloys were processed by a method that uses centrifugal force to cast the samples into a rotating copper mold. Microstructural characterization was carried out by means of x-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. Compressive tests at room and at 300 °C were performed in selected samples to evaluate their mechanical properties. Microstructural characterization showed the formation of quasicrystalline phases as well as other intermetallic phases embedded within an Al-FCC matrix. The Ce-containing alloy exhibited promising results regarding quasicrystalline phase formation and stability as well as with respect to its mechanical properties at high temperatures. The quasicrystalline phase of this alloy appears to be stable up to 545 °C when the DSC reveals an exothermic transformation. In addition, the presence of a eutectic structure surrounding the Al-FCC grains enhanced the mechanical strength of this alloy. At 300 °C, the Ce-containing alloy showed yield strength and ultimate tensile strength of 180 MPa and 360 MPa, respectively. If compared to a commercial aluminum alloy 2024 at the T6 condition, close to 300 °C, the alloy studied here showed an increase of more than 4 times in the yield strength, and almost 7 times in the ultimate tensile strength. The high thermal stability and mechanical properties at high temperatures of this alloy open interesting possibilities for further studies and future applications of this Al-Fe-Cr-Ce alloy.
       
  • The effect of Cu-doping on CdS thin films deposited by the spray pyrolysis
           technique

    • Abstract: Publication date: Available online 15 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Ahmed A. Aboud, Ayan Mukherjee, Neerish Revaprasadu, Ahmed Nagaty Mohamed Pure CdS and Cu-doped CdS thin films were deposited using the spray pyrolysis technique and characterized using XRD, XPS, AFM, UV-VIS spectroscopy and two probe DC-conductivity measurements. 2%, 4% and 6% Cu-content was used for doping. The particle size was found to decrease from 28 nm to 25.4 nm upon Cu-doping. The influence of Cu-doping on the stress and dislocation per unit volume has been estimated from the XRD data. AFM images of the annealed films show changes in morphology with increase in surface roughness from 25 nm to 31 nm with Cu-6% doping. Reflectance and transmission measurements were studied in the spectral range of 200–1100 nm to extract the optical properties variation upon copper doping. Also the band gap was found to decrease from 2.43 to 2.39 eV with increase in copper content. The electrical conductivity was measured by direct record of the resistance against temperature. All films show a semiconducting behavior and incorporation of Cu on CdS increases its activation energy.
       
  • Quantification of texture-induced ridging in ferritic stainless steels 430
           and 430LR during tensile deformation

    • Abstract: Publication date: Available online 15 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Xiaoguang Ma, Jingwei Zhao, Wei Du, Xin Zhang, Laizhu Jiang, Zhengyi Jiang A comparative study has been carried out to assess the effect of rolling and annealing processes on ridging generation of ferritic stainless steels (FSSs) 430 and 430LR after tensile deformation. The results show that FSS 430LR has better ridging resistance owing to the refinement of microstructure and crystallographic texture optimisation. A 30% reduction of ridging height can be achieved using FSS 430LR compared to FSS 430 after tension. Optimal reduction during cold rolling benefits the microstructural refinement and surface quality improvement of FSSs 430 and 430LR. Both theoretical calculations and experimental results indicate that the {1 1 2} and the {0 0 1} components are responsible for ridging in the FSSs after tension. Through preventing the formation of coarse bands and grains with the {0 0 1} component inside the FSSs, the ridging resistance of both FSSs 430 and 430LR can be improved.
       
  • Influence of Cu/Li ratio on the microstructure evolution of bobbin-tool
           friction stir welded Al–Cu–Li alloys

    • Abstract: Publication date: Available online 15 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Jannik Entringer, Martin Reimann, Andrew Norman, Jorge F. dos Santos Two modern aluminum lithium alloys were welded by semi-stationary bobbin tool friction stir welding. The influence of the Cu/Li ratio on precipitation phenomena under process heat impact was investigated by comparing the response of low Cu/Li alloy 2196-T8 and high Cu/Li alloy 2060-T8. Identical process parameters with a weld pitch of one rotation per mm were used to conduct flawless weldments. The thermal history and microstructural features were studied and correlated to the resulting mechanical properties of the welds. Analysis of microstructure using differential scanning calorimetry and high energy X-ray diffraction technique showed significant differences in the precipitation sequence of the base metal and in the welded samples of the two alloys of interest. A low Cu/Li ratio led to a higher softening resulting in a reduction of 43% of base metal yield strength while the high Cu/Li ratio alloy AA 2060 could demonstrate more thermal stability (38% reduction). Severe dissolution of the T1 precipitate and presence of equilibrium phases were confirmed for the stirred zone of both alloys. The heat affected zone suffered dissolution and overaging reactions leading to a mechanically unfavorable microstructure. The low Cu/Li alloy 2196 developed a higher process temperatures and exhibited a more evolved precipitation sequence.
       
  • Sintering behaviour of Co-28%Cr-6%Mo compacted blocks for dental
           prosthesis

    • Abstract: Publication date: Available online 14 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Bruno Xavier de Freitas, Carlos Angelo Nunes, Claudinei dos Santos In this work, the sintering behaviour of compacted CoCrMo blocks was investigated. The material was characterized in the as-received and sintered conditions through X-ray fluorescence, X-ray diffraction, density and scanning electron microscopy (SEM). The materials sinterability was evaluated by means of dilatometry and isothermal sintering at 800, 1000, 1200 and 1300 °C for different isothermal holding times. The particles of the as-received compacted blocks exhibited spherical shape with sizes ranging from 2 μm to 16 μm with a monomodal distribution. The as-received blocks presented a relative density of 57% and γCo(FCC) single-phase microstructure. After sintering, the specimens presented a γCo(FCC) + ɛCo(HCP) two-phase microstructure. Dilatometry data has indicated that the compacted blocks present discrete shrinkage anisotropy. Sintering starts close to 815 °C and a high shrinkage rate occurs near 1150 °C. The microstructure of the specimens sintered at 1200 °C has shown equiaxed grains and was highly dependent on the sintering time, with mean grain size ranging from 4.9 ± 1.3 μm (1200 °C – 60 min) to 28.4 ± 11.3 μm (1200 °C – 240 mm). The specimen sintered at 1200 °C – 240 min was in the final sintering stage and attained a densification near 90%. Sintering at 1300 °C – 60 min has led to exaggerated grain growth, with values of the order of 88.6 ± 16.7 μm and should be avoided because in addition it has not contributed to an increase in densification. The data from this work might be used to guide sintering cycles conditions for the manufacture of dental prostheses.
       
  • Synergy of rice-husk filler on physico-mechanical and tribological
           properties of hybrid Bauhinia-vahlii/sisal fiber reinforced epoxy
           composites

    • Abstract: Publication date: Available online 14 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Sandeep Kumar, Krishan Kant Singh Mer, Brijesh Gangil, Vinay Kumar Patel In this research, the effect of rice husk fillers were investigated on physical, mechanical and sliding wear properties of on hybrid Bauhinia-vahlii-weight (BVW) and Bauhinia-vahlii-weight/sisal (BVWS) fibers reinforced hybrid composites. The rice husk content was hybridized by loading variation of 0, 2, 4 and 6 wt% with 6 wt% BVW and combined 6 wt% BVW-Sisal fiber reinforced epoxy composites. The physical and mechanical properties like void fraction, water absorption, tensile strength, flexural strength, hardness, and impact energy in this research were found to be greatly influenced by rice-husk content. Moreover, the impact energy was found to be slightly decreased, owing to possible decrease in the deformability of the resin constituent. Rice husk filled BVWS composites exhibited improved tensile strength (34.42%), flexural strength (33%), and hardness (7.1%) as compared to BVW composites at all filler loading. The influence of selected control factors: sliding velocity, rice husk contents, normal load and sliding distance on specific wear rate of composites was investigated by Taguchi experimental design. Analysis of variance (ANOVA) was carried out to analyze the influence of each selected control factor on specific wear rate. The evaluated results demonstrate that rice husk content and sliding velocity were found to emerge the most noteworthy control factors among the others. Furthermore, the wear scars were analyzed by scanning electron microscopy to establish the governing wear mechanisms. This research established that the addition of rice husk fillers with optimum variation reflects the improvement in mechanical and wear performance of natural fiber based epoxy composites.
       
  • Impact properties of kenaf Fibre/X-ray films hybrid composites for
           structural applications

    • Abstract: Publication date: Available online 13 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): A.M.R. Azmi, M.T.H. Sultan, M. Jawaid, A.U.M. Shah, A.F.M. Nor, M.S.A. Majid, S. Muhamad, A.R.A. Talib Most existing designs of high velocity impact resistant materials are either heavy or expensive, so in markets the demand for lighter and cheaper materials is always on the rise. The aim of this work to investigates the effect of different projectile shape and impact velocities on the energy absorption and compression after impact of kenaf/X-ray/epoxy hybrid composites. Kenaf fibre treated with NaOH solution and perforated X-ray films were chosen as a reinforcement in the epoxy matrix to fabricate hybrid composites. The hybrid composites were fabricated using conventional hand lay-up method followed by compression moulding and were subjected to high velocity impact tests using a single stage gas gun. The pressure settings of the gas gun were varied as follows: 20 bar, 30 bar, 40 bar and 50 bar, while the projectiles used were of three types: blunt, hemispherical and conical ones. After the high velocity impact tests, the composites underwent dye penetration inspection and were subjected to compression after impact tests. The obtained results revealed that the hybrid composites subjected to high velocity impact with hemispherical projectile exhibited the highest energy absorption, compared to the conical and blunt geometry. On the other hand, the hybrid composites subjected to hemispherical projectile impact possess the lowest residual strength compared to conical and blunt geometry. The dye penetration test as well as the visual inspection also revealed that the hemispherical projectile produces the biggest damage compared to the other two projectile types. We concluded that developed kenaf/X-ray/epoxy hybrid composites suitable for ballistic applications.
       
  • Efficiency of dissimilar friction welded 1045 medium carbon steel and 316L
           austenitic stainless steel joints

    • Abstract: Publication date: Available online 13 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Gawhar Ibraheem Khidhir, Sherko A. Baban This study investigated the effects of frictional welding parameters on the microstructure and mechanical properties of dissimilar steel materials, namely, AISI 1045 medium carbon steel and AISI 316L austenitic stainless steel. The welded joints were produced by changing the forging pressure while the friction pressure, friction time, forging time and rotational speed were kept constant to achieve a constant range of temperature (780–800 °C). Experimental results showed that when the forging pressure increases, the hardness value of the weld interface increases whereas the tensile strength decreases. The hardness profiles also indicated that the welds exhibited higher hardness numbers than the two base metals. The highest weld joint efficiency obtained was 90% while the lowest was 63%. The joints failed in the thermo mechanical affected zone on the 316L austenite stainless steel side. Scanning electron microscopy attached with energy dispersive spectroscopy was used to analyse the fracture surface in the tensile test.
       
  • Work softening behavior of Cu–Cr–Ti–Si alloy during cold
           deformation

    • Abstract: Publication date: Available online 13 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Jihui Yuan, Liukui Gong, Wenqin Zhang, Bin Zhang, Haigen Wei, Xiangpeng Xiao, Hang Wang, Bin Yang Work hardening is a common method of strengthening copper-based alloys. However, softening behavior is observed in Cu–Cr–Ti–Si alloy during cold rolling processes. Cold deformation greater than 85% can induce softening behavior. We used an electron backscatter diffraction system, X-ray diffraction, and transmission electron microscopy to analyze the microstructure of alloy samples subjected to different degrees of cold deformation. A greater proportion of high-angle grain boundaries, a lower dislocation density, and certain dislocation configurations indicated that the recovery takes place during heavy cold deformation leading to softening phenomenon.
       
  • Different time's Nd:YAG laser-irradiated PVA/Ag nanocomposites:
           structural, optical, and electrical characterization

    • Abstract: Publication date: Available online 12 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Islam Shukri Elashmawi, Abdelrhman Anter Menazea Composite films of polyvinyl alcohol (PVA)/Silver nanoparticles (AgNPs) were synthesized via casting method. The presence of AgNPs in PVA was approved by an apparition of Surface Plasmon Resonance (SPR) around 427 nm of the composite absorption spectra. The nanocomposite films were irradiated at different times (5, 10, and 15 min) pulsed Nd:YAG laser. The integral intensity of diffracted X-ray photons from films has been increased noticeably after the doping process denotes increasing in the ordering character of the PVA/Ag nanocomposite irradiated to different time's laser, which can be assigned to the reduction that has been induced by laser. Observations of IR spectra indicated that laser enhances the structural modifications between the chains in PVA and the silver nanoparticles with further increasing laser irradiation time. The observed increase in refractive index (n) and the decreasing in the optical band gap of PVA/Ag nanocomposite films after irradiated to the laser with different times (5, 10, and 15 min) comparing with pure PVA suggesting its possibility to using optical device applications. The behavior of ɛ′ and ɛ″ are gradually decreased with the increase of the frequency. The value of ɛ′ and ɛ″ are decreases due to the contribution of interfacial polarization effect in dielectric permittivity. The relation between M’ and M″ depicts the formation of a semicircle arc indicating the presence of broad relaxation processes.
       
  • Silver and palladium nanoparticles produced using a plant extract as
           reducing agent, stabilized with an ionic liquid: sizing by X-ray powder
           diffraction and dynamic light scattering

    • Abstract: Publication date: Available online 12 March 2019Source: Journal of Materials Research and TechnologyAuthor(s): Francois Eya’ane Meva, Agnes Antoinette Ntoumba, Philippe Belle Ebanda Kedi, Edmond Tchoumbi, Alexa Schmitz, Laura Schmolke, Maximilian Klopotowski, Bastian Moll, Ülkü Kökcam-Demir, Emmanuel Albert Mpondo Mpondo, Leopold Gustave Lehman, Christoph Janiak Powder X-ray diffraction and dynamic light scattering (DLS) sizing of silver (Ag) and palladium (Pd) nanoparticles produced within aqueous plant extract and the effect of introducing of an ionic liquid are reported in this paper. The simple and novel synthesis of silver and palladium nanoparticles using the reducing power of Persea americana (Pa) bark extract is reported and the effect of adding 1-ethyl-3-methylimidazolium tosylate [EMIm][Tos] is described. Detailed powder X-ray interpretation allowed determination of the crystalline grain sizes of 16 ± 4 nm for Ag–Pa, 13 ± 2 nm for Ag–Pa[EMIm][Tos], 16 ± 3 nm for Pd–Pa and 9 ± 1 nm for Pd–Pa[EMIm][Tos] according to the Scherrer peak analysis. A size contraction occurs when moving from plant extract alone to plant extract/ionic liquid. These grain sizes are 9 nm for Ag–Pa and for 9 nm Ag–Pa[EMIm][Tos], 15 nm for Pd–Pa and 7 nm for Pd–Pa[EMIm][Tos] when the Williamson–Hall plot intercept is used. Modal hydrodynamic sizes were determined by DLS as 57 nm for Ag–Pa, 72 nm for Ag–Pa[EMIm][Tos], 390 nm for Pd–Pa and 98 nm for Pd–Pa[EMIm][Tos] providing indications on how the particles behave in solution. Intrinsic stresses of 0.177 GPa for Ag–Pa, 0.219 GPa for Ag–Pa[EMIm][Tos], 0.382 GPa for Pd–Pa and 0.190 GPa for Pd–Pa[EMIm][Tos] and dislocation densities of (6 ± 3) × 10−3 nm−2 for Ag–Pa, (9 ± 3) × 10−3 nm−2 for Ag–Pa[EMIm][Tos], (5 ± 2) × 10−3 nm−2 for Pd–Pa and (16 ± 4) × 10−3 nm−2 for Pd–Pa[EMIm][Tos] have been obtained.
       
  • Photocatalytic performance of N-doped TiO2nano-SiO2-HY nanocomposites
           immobilized over cotton fabrics

    • Abstract: Publication date: Available online 23 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Salmon Landi, Joaquim Carneiro, Olivia S.G.P. Soares, Manuel F.R. Pereira, Andreia C. Gomes, Artur Ribeiro, António M. Fonseca, Pier Parpot, Isabel C. Neves This work reports the synthesis of nanocomposite photocatalytic materials based on nitrogen-doped TiO2nano, SiO2 and different percentages of HY zeolite (0, 12, 25 and 50%). These materials were characterized by using Fourier transformed infrared spectroscopy, X-ray diffraction, N2 adsorption–desorption, UV-vis diffuse reflectance spectroscopy and scanning electron microscopy. The nanocomposites, which presented an energy band gap of about 3.03 eV, were immobilized on cotton fabric and their self-cleaning properties were investigated by decolourization of rhodamine B (RhB) dye in aqueous solution under simulated solar irradiation. The fabrics coated with the photocatalysts, containing and not containing zeolites, showed the same RhB decolourization (about 95%) after 5 h, excluding the situation where a large amount of HY (50%) was used in the nanocomposites. However, results obtained from high performance liquid chromatography analysis depicted that in the presence of the HY zeolite a more effective RhB degradation was achieved. In fact, even after the use of five consecutive cycles, the RhB decolourization remained high (about 85%). Generally, the photodegradation of RhB solution in the presence of cotton fabrics functionalized with TiO2nano, TiO2nano-SiO2 and TiO2nano-SiO2-0.25 HY resulted in the formation of products that exhibited a similar cytotoxic effect when compared to the untreated RhB solution and subjected to the same tested concentrations and incubation times.
       
  • High-density polyethylene/mollusk shell-waste composites: effects of
           particle size and coupling agent on morphology, mechanical and thermal
           properties

    • Abstract: Publication date: Available online 22 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): P.M.A. Melo, O.B. Macêdo, G.P. Barbosa, M.M. Ueki, L.B. Silva Composites based on high-density polyethylene (HDPE) and mollusk shell-waste (MSW) particles, with several concentrations and two different micro-sizes, were prepared by melt compounding and injection molding. The matrix flow behavior was not altered by the MSW incorporations. SEM analyses revealed weak filler/matrix interfacing and the presence of agglomerates (in the composites with higher particle concentrations). For the 2 wt% composites, good filler dispersion and distribution was observed in the HDPE matrix. The crystallinity of the matrix increased approximately 10% when adding lower MSW concentrations. For the composites with higher MSW concentrations and finer particles the thermal degradation temperature of HDPE (at a 20% mass loss) increased by approximately 26 °C. The tensile modulus increased by approximately 10% for the 2 wt% and 8 wt% composites with coarse particles. With lower MSW concentrations and finer particles, the flexural modulus increased by more than 37%. The composites modified with titanate presented properties similar to unmodified composites. Molecular interactions were verified by the presence of a band at 1030 cm−1, yet were not sufficient to promote improvements in the mechanical properties of the modified composites.
       
  • The effects of non-metallic inclusions on properties relevant to the
           performance of steel in structural and mechanical applications

    • Abstract: Publication date: Available online 22 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): André Luiz Vasconcellos da Costa e Silva Non-metallic inclusions (NMIs) occur typically in low or very low volume fractions (from 10−2 in a high oxygen weld deposit to 10−5 in very clean bearing steels) but play an important role in many properties of steel. NMIs play a decisive role in processes involving ductile fracture, fatigue and corrosion, for instance. These are some of the properties more relevant to the performance of steel in structural and mechanical applications. Furthermore, NMIs may influence nucleation during phase transformations of steel. In this work, the relation of these properties to NMIs is reviewed, highlighting progress and difficulties in each area. Perhaps because of their very low volume fraction, NMIs are sometimes overlooked in the basic physical metallurgy education and their study is left to the realm of those interested in steelmaking. In the last decades a dramatic evolution in the understanding of their relationship to properties, however, has led to significant improvements in many steel products: the outstanding increase of fatigue life in automotive springs and in bearings is one of many such examples. It is concluded that steel improvement in many cases requires “inclusion engineering” and this can only be achieved through close collaboration between physical metallurgy, process metallurgy and steelmaking. Those who realized this have made significant progress in steel development in recent decades as highlighted in this short review.
       
  • Effect of the roughness produced by plasma nitrocarburizing on corrosion
           resistance of AISI 304 austenitic stainless steel

    • Abstract: Publication date: Available online 20 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Paula Cisquini, Simão Vervloet Ramos, Pedro Rupf Pereira Viana, Vanessa de Freitas Cunha Lins, Adonias Ribeiro Franco, Estéfano Aparecido Vieira In this work, we studied the influence of surface roughness produced by sputtering during plasma nitrocarburizing treatments on corrosion resistance of AISI 304 austenitic stainless steel in an aqueous solution of sodium chloride. Plasma nitrocarburizing treatments were carried out in a gaseous atmosphere containing 80% N2 + 2% CH4 + 18% H2, at 400 Pa, for 2 h and at temperatures of 375 °C, 430 °C and 475 °C. Surface roughness after plasma nitrocarburizing was characterized using 3D confocal microscopy. Corrosion susceptibility of the plasma nitrocarburized surfaces was investigated by electrochemical impedance spectroscopy, potentiodynamic polarization, and scanning electron microscopy. The results showed that when increasing the temperature of the plasma nitrocarburizing treatment, both thickness and amount of precipitates increased, as expected. Analyses by 3D confocal microscopy also showed increased surface roughness with increasing plasma nitrocarburizing temperature. When comparing two plasma nitrocarburized specimens with similar precipitate-free structure, it was found that thinner thickness of the expanded austenite layer and lower surface roughness resulted in higher corrosion resistance.
       
  • The EAF dust chemical and phase composition research techniques

    • Abstract: Publication date: Available online 19 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Laura M. Simonyan, Anna A. Alpatova, Nadezhda V. Demidova Study of EAF steel dust composition is essential for the development and implementation of the environmentally friendly and cost-effective metallurgical processes. Content of metal oxides and complex composition of EAF dust (sulfides, silicates, carbonates and other) has been evaluated with the use of TERRA thermochemical software package and analyzed by combination of XRD analysis and Mössbauer spectroscopy. It was found that each of the used techniques has its own application niche. Specifically, thermodynamic modeling enables one to additionally specify those chemical compounds which have not been detected by other analysis techniques.
       
  • Thermoplastic deformation behavior of a Fe-based bulk metallic glass
           within the supercooled liquid region

    • Abstract: Publication date: Available online 19 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): S.M. Song, Y.C. Liao, T.H. Li, C.K. Lee, P.H. Tsai, J.S.C. Jang, J.C. Huang Fe41Cr15Co7Mo14C12B9Y2 (Fe-B9) bulk metallic glass (BMG) rods with high glass forming ability and large supercooled liquid (SCL) region were fabricated by arc melting and suction casting. The amorphous state of these Fe-B9 BMG rods was ascertained by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The thermoplastic deformation behavior of these BMG rods was studied by using the hot compression test at different temperatures (873 K, 883 K, 893 K, and 903 K in the SCL region) and strain rates (1 × 10−3–5 × 10−2 s−1). The results of the hot compression test reveal that the flow stress of Fe-B9 BMG reduces systematically with increasing temperature and decreasing strain rate. Strain sensitivity exponent (m) values of the Fe-B9 BMG were calculated to be about 0.36–0.59 in the SCL region, indicating that Fe-B9 BMG possesses superplasticity. Overall, the optimum working conditions of thermoplastic forming for Fe-B9 BMG can be achieved by compressively deforming the sample with a constant strain rate of 2.5 × 10−3 s−1 at a temperature from 873 to 883 K.
       
  • Retained austenite phase detected by Mössbauer spectroscopy in ASTM A335
           P91 steel submitted to continuous cooling cycles

    • Abstract: Publication date: Available online 19 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Jorge I. Besoky, Claudio A. Danon, Cinthia P. Ramos Samples of ASTM A335 P91 steel submitted to continuous cooling at different rates were analyzed in the form of foils and powders by means of Mössbauer spectroscopy. The Continuous Cooling Transformation (CCT) diagram of steel ASTM A335 P91 displays two basic microstructural domains at low temperatures – ferritic and martensitic – whose limits depend on the austenite holding temperature, the precise chemical composition and the cooling conditions from the austenite mother phase. Under certain conditions, the martensitic transformation may not be completed, leading to a final microstructure with a non-negligible percentage of the austenite phase retained in a metastable state. This retained austenite could be detrimental for the mechanical properties of the steel.Mössbauer analysis suggested that powdering process promotes the retained austenite transformation to martensite; in particular, in the present case, all the austenite transformed into martensite during powdering. Foil samples instead displayed retained austenite whose relative fraction was determined as a function of the cooling rate. At the same time, the carbon content of retained austenite was estimated for the faster cooled samples; a preliminary explanation for the observed trends is given.
       
  • A constitutive relation of AZ80 magnesium alloy during hot deformation
           based on Arrhenius and Johnson–Cook model

    • Abstract: Publication date: Available online 18 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Xingrui Chen, Qiyu Liao, Yanxia Niu, Weitao Jia, Qichi Le, Chunlong Cheng, Fuxiao Yu, Jianzhong Cui In order to understand the constitutive behavior of as-cast AZ80 with large grain size, the uniaxial hot compression tests were carried out over a series of isothermal upsetting experiments. The maximum deformation degree was 65%. The experimental temperatures were 523 K, 573 K, 623 K and 673 K and the strain rate was 0.001 s−1, 0.01 s−1, 0.1 s−1, and 1 s−1. The stress–strain curves can be divided into three stages which are work hardening stage, softening stage, and steady-state stage at low strain rate and high temperature, while the steady-state stage cannot be observed at low forming temperature and high strain rate because of incomplete dynamic recrystallization. The Arrhenius type relation predicts the peak stress with high accuracy but cannot satisfy the strain relevant requirement. The Johnson–Cook model shows an inappropriate ability to describe the constitutive behavior in this case. Therefore, a new mathematic model (a segmented model) with high prediction accuracy based on the modified Arrhenius type relation (including strain rate) and Johnson–Cook model is proposed. The modified Arrhenius type relation is used to reflect the constitutive behavior before the peak strain and the modified Johnson–Cook model is aimed at showing the stages after peak strain.
       
  • Mechanical and electrochemical characteristics of solutionized AA 6061,
           AA6013 and AA 5086 aluminum alloys

    • Abstract: Publication date: Available online 18 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): E. F. Abo Zeid The current study was conducted to investigate the effect of age hardening on three different aluminum alloys: AA 6061, AA6013 and AA 5086. Different characterizing and testing techniques were utilized in this study. The XRD results for 6xxx series demonstrated the Mg2Si formation with different orientations after natural and artificial aging (NAT and AAT), while MgZn2 phase was depicted in AA 5086 alloy. The friction coefficient of all naturally aged Al alloys at room temperature (RT) was found to be higher than the friction coefficient of the artificially aged Al alloys at 175 °C. For group series 6xxx the corrosion resistance was decreased after the natural aging at RT, while the corrosion resistance was improved after artificial age treatment at 175 °C for 30 min (AAT). The reduction in the friction coefficient and the growing in the corrosion resistance of the Al alloys after artificial age hardening make them potentially be used in many industrial sectors.
       
  • Intergranular corrosion evaluation of friction stir welded AISI 410S
           ferritic stainless steel

    • Abstract: Publication date: Available online 18 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Gerbson de Queiroz Caetano, Cleiton Carvalho Silva, Marcelo Ferreira Motta, Hélio Cordeiro Miranda, Jesualdo Pereira Farias, Luciano Andrei Bergmann, Jorge F. dos Santos This study aimed to investigate the susceptibility of AISI 410S ferritic stainless steel to intergranular corrosion when friction stir welded (FSW) using the double-loop electrochemical potentiokinetic reactivation (DL-EPR) test. The highest values obtained for the ratio between the reactivation current (Ir) and the activation current (Ia) were found at the top of the advancing side for the two conditions tested. The steel for Condition 1, which was welded with a rotational speed of 800 rpm and high heat input, gave Ir/Ia peaks 60% greater than Condition 2, which was welded with a rotational speed of 450 rpm and a lower heat input. These peaks were attributed to the presence of precipitates with high chromium content of about 21%. In these FSW welds the sensitization of the AISI 410S steel was detected by the electrochemical test according to the intensity of the undesirable phases formed. The DL-EPR test was clearly able to quantify the different levels of sensitization in the FSW welds according to the energy used by the process parameters.
       
  • Effects of geometry and hybrid ratio of steel and polyethylene fibers on
           the mechanical performance of ultra-high-performance fiber-reinforced
           cementitious composites

    • Abstract: Publication date: Available online 16 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Min-Jae Kim, Doo-Yeol Yoo, Young-Soo Yoon This study aims to examine the several factors influencing the efficiency of the hybridization of steel and polyethylene (PE) fibers in improving the compressive strength and tensile performance of ultra-high-performance fiber-reinforced cementitious composites (UHPFRCC). For the mechanical tests, three types of steel fibers (i.e., short straight steel (SS), medium-length straight steel (MS), and twisted steel (T) fibers) and four lengths of polyethylene (PE) fibers (i.e., 12 mm (SPE), 18 mm (MPE), 27 mm (LPE), and 36 mm (LLPE)) were hybridized. Each specimen included 2 vol.% of single or hybrid fibers, and the hybrid ratio was controlled by replacing 0.5% of the steel fibers with the same amount of PE fibers from 0 to 2%. Thus, a total of 7 single and 36 hybrid UHPFRCC specimens were fabricated. From the test results, it was found that the compressive strength decreased proportionally to the PE fiber content, but the decrease was more severe in hybrid specimens, including 1.5% PE fibers, than single fiber specimens, including 2.0% PE fibers. The tensile strength also decreased with an increase of PE fiber content, whereas strain capacity and energy absorption capacity per unit volume substantially improved with the inclusion of PE fibers. The SPE fibers showed the best hybridizing efficiency among PE fibers in improving the tensile strain capacity and energy absorption capacity of UHPFRCC, and the use of T fibers was the most effective in terms of cracking behavior.
       
  • Synthesis of modified bismuth tungstate and the photocatalytic properties
           on tetracycline degradation and pathways

    • Abstract: Publication date: Available online 11 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Shuang Zhong, Chenyang Li, Mengnan Shen, Chen Lv, Shengyu Zhang This study adopted a solvent-thermal method with an added dispersing agent to successfully prepare modified bismuth tungstate (Bi2WO6) catalysts, which were characterized by X-ray diffraction, scanning and transmission electron microscopies, X-ray photoelectron and ultraviolet–visible diffuse reflectance spectroscopies, and photoluminescence. According to the results, the addition of a dispersing agent helped in preparing Bi2WO6 catalysts with appropriate morphology and structures, without influence on its purity, and modestly narrowed the forbidden bandwidth to 2.42 eV, effectively improving the catalysts’ visible light catalytic activity and exhibiting a 90.39% degradation of tetracycline after 60 min of irradiation. A possible pathway for TC degradation, based on its structure, was analyzed to better understand the reaction mechanisms in solution and TC found to be degraded first to some intermediate products and then the intermediate products degraded to CO2, H2O, and other small molecules.
       
  • Microstructure and texture characterization of Mg–Al and Mg–Gd binary
           alloys processed by simple shear extrusion

    • Abstract: Publication date: Available online 8 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): N. Bayat Tork, H. Saghafian, S.H. Razavi, K.J. Al-Fadhalah, R. Ebrahimi, R. Mahmudi Microstructural and textural evolutions of pure Mg, Mg–2 wt% Al, and Mg–2 wt% Gd were investigated after extrusion and simple shear extrusion (SSE). Microstructural studies revealed that the grain size of all extruded samples decreased after 4 passes of SSE at 553 K (280 °C). In the fine-grained Mg–2Gd alloy, however, a duplex structure consisting of fine recrystallized grains and coarse unrecrystallized patches was formed. Although the 2.5 μm size of the recrystallized grains did not experience a significant change, the volume fraction of the coarse 15 μm-wide unrecrystallized patches decreased, and the overall microstructural homogeneity was improved after 4 passes of SSE. In Mg–2Gd, fragmentation of large grains and unrecrystallized patches encouraged the formation of HAGBs, while Mg–2Al did not experience significant changes in the fraction of HAGBs. Contrary to pure Mg and Mg–2Al alloy, Mg–2Gd alloy developed a new “rare earth texture component” with the 〈1 1 2¯ 1〉 direction parallel to the extrusion direction in the extruded condition. However, all three materials developed the conventional “extrusion texture” after SSE.
       
  • Microstructure and mechanical properties of Mg–Zn–RE–Zr
           alloy after thixoforming

    • Abstract: Publication date: Available online 2 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Lukasz. Rogal, Adrianna. Kania, Katarzyna. Berent, Karol. Janus, Lidia. Lityńska-Dobrzyńska Magnesium is particularly challenging material, when formed from liquid phase because of high flammability risk. An alternative process for casting, which eliminates above mentioned disadvantage, is thixoforming, which involves a lower temperature of process and operation in the partially solidified state. Influence of semi-solid metal processing on EZ33A magnesium alloy (Mg–Zn–RE–Zr) microstructure and mechanical properties was studied. Ingot microstructure revealed globular grains with coarse eutectic mixture consisting of Mg7Zn3RE, T-phase – RE(Mg,Zn)11 and α(Mg). Heterogeneous nucleation of magnesium solid solution allowed obtaining structure appropriate for thixoforming. Using differential scanning calorimetry, temperature of process was determined to be 622 °C, which corresponded to about 30% of the liquid phase. Thixo-cast microstructure consisted of α(Mg) globular grains with a size of 76 ± 1.1 surrounded by fine eutectic mixture in a volume of 35%. T6 heat treatment (solution at 500 °C for 6 h and ageing at 190 °C for 33 h) caused increase of grain size to 92 μm and the precipitation of two kinds of phases within the α(Mg): β′1 and β′2 responsible for the increase of yield strength to 135 MPa, compression strength to 383 MPa and hardness to 73 HV5.
       
  • CFD modelling of friction stir welding (FSW) process of AZ31 magnesium
           alloy using volume of fluid method

    • Abstract: Publication date: Available online 1 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): A.F. Hasan In this work, a validate couple-thermo flow model of the FSW process is generated using the CFD software FLUENT, with this model, then being developed to model the flash formation phenomena that occur during the FSW process using the volume of fluid method. From both models, pressure distribution on the tool surface was predicted at different radial positions. A comparison was made between single and multiple phase flow models. A significant reduction of the pressure values was seen when using a two-phase flow model. Volume fraction contour showed the changing in the metal phase when increased the welding time steps. A modelling procedure of this work is presented in details to utilize it in the further numerical investigation as a guide. This work could be used to afford more understanding of surface flash formation phenomena. Moreover, the outcome of this study can be a useful technique to aid the tool failure and increase the tool life during the FSW process.
       
  • Factors affecting CO oxidation reaction over nanosized materials: A review

    • Abstract: Publication date: Available online 1 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): N.K. Soliman The high level of carbon monoxide (CO) in the atmosphere represents a serious health and environmental problem, thus many techniques were used to reduce CO concentration. The catalytic oxidation of CO proves to be one of the most effective techniques for removing this pollutant. In this paper, we review the factors that affect CO oxidation reaction, such as catalyst crystal size, pre-treatment and preparation technique, temperature including calcination and catalytic reaction temperature, catalyst mass, and water vapor on feedstock gas. The main findings of the present review are: (1) The catalyst used in the oxidation of CO to CO2 must have extraordinary CO oxidation activity, high selectivity, and respectable resistance toward deactivation by H2O and CO2; (2) Metal oxides nanoparticles are found to be favorable and effective catalysts for CO oxidation; (3) CO oxidation greatly affected by catalyst crystal size where it generally increases with reducing crystal size to a certain limit and after that the CO conversion % decrease; (4) Preparation methods affect the catalytic process as its effects on the surface area and the dispersion of the nanostructure prepared catalyst; (5) Temperature greatly affects CO oxidation catalysts. Thus, carbon monoxide catalytic materials have to work even at higher temperatures; (6) Increasing catalyst weight generally increases catalytic activity due to the increase in the total surface area and a number of active places on the surface of the catalyst; (7) H2O vapor on feedstock gas sometimes have positive effects and other time have negative effects on the catalytic oxidation of CO. Knowing the factors that affect CO oxidation over nanosized materials will help in optimizing the condition for CO oxidation over specific nanosized catalyst.
       
  • Effect of delta ferrites on the anisotropy of impact toughness in
           martensitic heat-resistant steel

    • Abstract: Publication date: Available online 1 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Junru Li, Lianjun Cheng, Pengfei Zhang, Liwei Wang, Hong Li To avoid brittle failure of the final-stage turbine blades, it is necessary to understand the anisotropy mechanism in martensitic heat-resistant steel 10Cr12Ni3Mo2VN. This study focused on the effect of delta ferrites on the anisotropy of impact toughness by investigating the relationship between the microstructures and the anisotropy of impact toughness. It was mainly interested in the effect of banded delta ferrites on the transverse impact toughness of experimental steel after quenching and tempering. It was found that banded delta ferrites cause banded brittle cracks and induce tempered martensite matrix to fracture in quasi-cleavage mode, which leads to the embrittlement in transverse specimens and the anisotropy of impact toughness. The embrittlement caused by banded delta ferrites is unrelated to other precipitates such as M23C6-type carbides or MX-type precipitates. In addition, by removing the banded delta ferrites, it can eliminate the anisotropy of impact toughness in the experimental steel. It was also found that conventional heat treatment could not improve the isotropy of impact toughness since it has little influence on the content of banded delta ferrites. As suggested, the use of upsetting-stretching forging strategy promises a great of improvement of isotropy of impact toughness as it can remarkably reduce the amount of banded delta ferrites.
       
  • Sol–gel coatings doped with encapsulated silver nanoparticles:
           inhibition of biocorrosion on 2024-T3 aluminum alloy promoted by
           Pseudomonas aeruginosa

    • Abstract: Publication date: Available online 1 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): E.A. González, N. Leiva, N. Vejar, M. Sancy, M. Gulppi, M.I. Azócar, G. Gomez, L. Tamayo, X. Zhou, G.E. Thompson, M.A. Páez Silanol type hybrid polymers modified with silver nanoparticles encapsulated with SiO2 for biocorrosion protection of 2024-T3 aluminum alloy were studied through electrochemical characterization and surface analysis techniques. Two different encapsulated silver nanoparticles were synthesized using tetraethoxysilane as a core shell. The hybrid polymer was prepared by the sol–gel technique by mixing tetraethoxysilane and triethyl(octyl)silane in 1-propanol, followed by the incorporation of silver nanoparticles or encapsulated silver nanoparticles. Relatively uniform coatings were observed by a scanning electron microscopy analysis. Transmission electron microscopy and dynamic light scattering results indicated that the diameter of the silver nanoparticles was around 20 nm, whereas the encapsulated silver nanoparticles presented diameters between 24 and 30 nm. The viability results showed that polymers modified with encapsulated nanoparticles exhibit higher antibacterial properties than the polymer modified with free silver nanoparticles. This fact may be associated with a higher hydrophobicity of the coatings modified with silver encapsulated nanoparticles. Additionally, impedance measurements revealed a protective effect of all synthesized coatings for 2024-T3 aluminum alloy in chloride media inoculated with Pseudomonas aeruginosa.
       
  • Use of manufacture residue of fluidized-bed catalyst-cracking catalyzers
           as flame retardant in recycled high density polyethylene

    • Abstract: Publication date: Available online 1 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Sidney Martins, Maiccon Martins Barros, Patricia Soares da Costa Pereira, Daniele Cruz Bastos The Municipal Company of Urban Cleaning uses plastic lumber to manufacture urban furniture items, whose process generates a post industrial waste scrap that is recycled once again. The Fábrica Carioca de Catalisadores produces catalysts for oil cracking in fluidized bed. This production process creates an inorganic solid residue with prospective flame retardant property in polymeric materials. This inorganic residue is currently sent to licensed landfill. The goal of the present work was to test the use of this inorganic solid waste from the manufacture of fluidized-bed catalytic cracking catalysts as flame retardants agent in polymer–matrix composites of rHDPE. The materials were processed in a Haake internal mixer, and the rHDPE/inorganic residue composites were compounded in the 100/0, 80/20, 60/40 and 40/60 proportions, by weight percentage. The composite materials were characterized by: flammability tests, tensile tests; TG/DTG, DSC and SEM. The results of the horizontal firing tests performed clearly showed that the incorporation of inorganic residue into the polymer material fostered the increase on fire resistance. The TG curves showed that the thermal decomposition of the material occurred between 480 and 500 °C. The DSC curves of the residue showed a characteristic peak of alumina dehydration, below 300 °C. The tensile test results demonstrated that when 20% residue was added, the Young's modulus of the rHDPE increased by about 17% but the tensile strength was similar to rHDPE. The incorporation of inorganic particles into the polymeric matrix resulted in a change in the behavior of the material – from ductile to brittle – as observed by SEM micrographs.
       
  • Strain hardening analysis and modelling of its parameters for sintered Al
           and Al-1%C preforms during cold upsetting

    • Abstract: Publication date: Available online 1 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Rajeshkannan Ananthanarayanan, Zoher Ahmed, Avneet Prasad, Sumesh Narayan An attempt has been made to model strain hardening parameters for sintered aluminium and aluminium-1%carbon preforms that are subjected to cold upsetting. In addition to compositions, the sintering temperatures and lubricants are considered as variables. The 2k factorial design has been considered to design the experiment and subsequently Yate's algorithm is utilized to construct the model. The model has further been refined using analysis of variance and model adequacy is determined through correlation coefficient which is predicted to follow near unity. Thus, this model can be utilized to predict strain hardening parameters such as strength coefficient, K, and strain hardening exponent, n, subsequently to design the process parameters to inculcate the required strain hardening characteristics within the range of process parameters specifications that are considered in the present investigation.
       
  • Effect of ball milling and cryomilling on the microstructure and first
           hydrogenation properties of TiFe+4 wt.% Zr alloy

    • Abstract: Publication date: Available online 1 February 2019Source: Journal of Materials Research and TechnologyAuthor(s): Peng Lv, Matylda N. Guzik, Sabrina Sartori, Jacques Huot In this paper, we report the microstructure and first hydrogenation properties of TiFe cast with 4 wt.% of Zr. Measurements were made in as-cast state and after processing by ball milling and cryomilling. It was found that ball milling and cryomilling significantly reduced the particle/crystallite sizes with most of the reduction occurring during the first 15 min of milling. While the cryomilled sample did not absorb any hydrogen, ball milling improved the initial kinetics of processed powders compared with the as-cast sample. However it also reduced the hydrogen storage capacity. The observed increased kinetics was likely caused by the reduction of crystallite sizes with longer ball milling times. However, the longer ball milling times might also be the reason of the capacity loss due to formation of new grain boundaries. Faster kinetics was not due to a change in the rate-limiting step, as all kinetics curves were fitted with the 3D growth, diffusion controlled with decreasing interface velocity model.
       
  • Effective utilization of Moringa seeds waste as a new green environmental
           adsorbent for removal of industrial toxic dyes

    • Abstract: Publication date: Available online 31 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Nofal khamis Soliman, Ahmed Fathy Moustafa, Ahmed A. Aboud, Khaled Saad Abdel Halim The Moringa seeds waste (MSW), which resulted from the oil extraction industry, contains many varieties of natural organic components such as flavonoid, tannins, phenolic and hydrolyzable carbohydrates. The MSW could be considered a promising and an efficient green adsorbent for wastewater treatment as it reduces the environmental impact of hazardous chemicals existing in the industrial wastewater. The present work is designated to clarify the possibility of using MSW for the removal of industrial dispersed red 60 (DR60) and Congo Red (CR) dyes from aqueous solutions. The factors affecting the adsorption process such as initial dye concentration, catalyst weight, pH value, and solution temperature were investigated. It was found that the adsorption rate for both dyes was very high at the initial stages of the process and then decreases until reaches the equilibrium. The adsorption rate of the DR60 dye was not affected by catalyst weight, pH or the solution temperature. Whereas the percentage of the CR dye removal is found to be 100% for all dyes concentrations except for the CR dye with high initial concentration (100 mg/L), which reached only 85.3%. It was observed that the adsorption % of CR dye increases by increasing the temperature from 25 to 40 °C. With more increases in the reaction temperature from 40 to 80 °C, the CR removal decreases from 88.7 to 57.7%, respectively. This behavior can be attributed to the desorption behavior of the adsorbed dye molecules at a higher temperature. Accordingly, the optimum temperature for the CR dye adsorption is found at 40 °C. A detailed study of the dye adsorption isotherms and kinetics was carried out and the results show that the dyes adsorption isotherms and kinetics are followed by Freundlich and pseudo-second-order models. Maximum amounts of dyes adsorbed were found to be 170.7 and 196.8 mg/g for both CR and DR60 dyes, respectively, at 100 mg/L concentration, 25 °C and pH 7. The overall rate of adsorption process seems to be controlled by a chemical process mechanism involving valence forces through exchange or sharing of electrons between dyes and MSW adsorbent.
       
  • An extensive study on the synthesis of iron based magnetic aluminium oxide
           nanocomposites by solution combustion method

    • Abstract: Publication date: Available online 31 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Merve Pehlivan, Sinem Simsek, Sunullah Ozbek, Belma Ozbek In the present study, it was aimed to investigate the synthesis of iron based magnetic aluminium oxide nanocomposites (IMANCs) by solution combustion (SC) method using various fuel types at various amounts. IMANCs were synthesized using aluminium nitrate and iron nitrate as oxidizers. Urea, glycine and sucrose were chosen as fuel types at various amounts, respectively, to examine their effects on size and morphology of nanocomposites synthesized. The chemical compositions, morphologies and thermal behaviors of IMANCs synthesized were compared with data obtained from characterization studies using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), Thermogravimetric and Differential Thermal Analysis (TG/DTA), Fourier Transform Infrared Analysis (FT-IR), Surface Area and Porosity Analyzer. The characterization studies revealed that IMANCs were synthesized successfully by SC method with nanoscale properties. It was found that IMANCs synthesized using stoichiometric amount of glycine had porous and smaller particle size with higher surface area compared to other samples synthesized by urea and sucrose, respectively. There is no documentation found on glycine based synthesis of IMANCs by SC method in the literature so far. Additionally, this original paper is the first report on the synthesis of IMANCs by applying calcination and reduction processes following SC reaction using various fuel types at various amounts. It was resulted that the samples synthesized by SC method had smaller particle sizes compared to the samples which were synthesized by applying calcination and reduction processes following SC reaction using stoichiometric amount of urea, glycine and sucrose as fuel types, respectively.
       
  • Modification of coking properties due to oxidation. Effect of relative
           humidity

    • Abstract: Publication date: Available online 31 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): M.F. Vega, E. Díaz-Faes, C. Barriocanal This work is a systematic laboratory study of coal oxidation under well-controlled temperature and humidity conditions that attempts to simulate those found in the transport and storage of coking coals. Four bituminous coals of different rank were oxidised at 50 °C under different humidity conditions in order to establish the effect that the moisture of the air medium has on their coking properties. The effect of oxidation was examined by means of the free swelling index (FSI), the Gieseler test, thermogravimetry and coke microstrength measurements. The point of zero charge (pHPZC) was explored as a possible method for detecting coal oxidation.In general, the results obtained revealed a deterioration of the thermoplastic properties, a decrease in the point of zero charge and a diminution of the maximum rate of volatile matter evolution. It was observed that the highest humidity level (90% rh) retarded the oxidation of the lowest rank coal during the first few days of oxidation, whereas the higher rank coals were affected more by high humidity conditions. It was also found that low volatile coals become more dangerous after oxidation regardless of the humidity conditions. No significant variations were observed in the mechanical strength of the resultant cokes attributable to the humidity conditions.
       
  • Microstructure assessment at high temperature in NiCoCrAlY overlay coating
           obtained by laser metal deposition

    • Abstract: Publication date: Available online 22 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Juan C. Pereira Falcón, Alberto Echeverría, Conrado R.M. Afonso, Jenny C. Zambrano Carrullo, Vicente Amigó Borrás Laser metal deposition (LMD) and laser cladding (LC) could be innovative methods to the current thermal spray techniques for obtaining dense and high-quality bond coats with nickel and cobalt based superalloys in thermal barrier coatings (TBCs) systems. The microstructural evolution of the coatings when is subjected to high temperatures allows us to evaluate their oxidation behavior and integrity in the time, and is especially important in the development of bond coats for new TBCs systems. In this work, the microstructural evolution of a dense NiCoCrAlY overlay coating obtained by coaxial laser cladding and subjected to isothermal oxidation tests at 1100 °C up to 200 h was evaluated. The initial coating microstructure is composed of a β-NiAl phase within the γ-Ni matrix phase, and some Y inclusions, confirmed by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). At high temperature, the thermally-grown oxides (TGO) protect the underlying coating and substrate from oxidation, modifying the initial microstructure of the coating. The formation, morphology and evolution of oxides α-Al2O3, Y2O3, YAlO3 and (Ni,Co)(AlCr2)2O4-type spinel oxides on the cross section of the oxidized coating on different oxidation stages were evaluated using focused ion beam (FIB) and field emission scanning electron microscopy (FESEM), and indexed by XRD and TEM. After oxidation tests, no cracks or spallation on oxidized sample for NiCoCrAlY coating were observed, and the formation of Y-Al oxides in TGO scale are strongly dependent on the initial Y distribution of as-built condition in the coating.
       
  • Study of the high temperature oxidation and Kirkendall porosity in
           dissimilar welding joints between FE-CR-AL alloy and stainless steel AISI
           310 after isothermal heat treatment at 1150 °C in air

    • Abstract: Publication date: Available online 18 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): André de Albuquerque Vicente, Joao Roberto Sartori Moreno, Denise Crocce Romano Espinosa, Tiago Felipe de Abreu Santos, Jorge Alberto Soares Tenório Dissimilar welded joints of Fe-Cr-Al alloy (23Cr-7Al) and AISI 310 austenitic stainless steel (25Cr-20Ni) were studied and characterized, before and after the isothermal heat treatment (IHT) of oxidation at 1150 °C for 936 h in air. The Fe-Cr-Al alloy was used as the welding consumable and the welding process used was gas-shielded tungsten arc welding (GTAW) with currents of 60, 80 and 130 amps, and welding speed 1, 1.1 and 1.3 mm/s. In the heat treated specimens, pore formation was observed as well as significant variations of Al contents in all-welded metals and formation of protective layer of alumina-Al2O3 on the oxidized surfaces particularly in the sample 1, welded at 60 amps and welding speed of 1 mm/s, that showed higher pore index and a greater deflection in the decrease of the Al content. The formation of Kirkendall pores occur due to the rapid diffusion of the aluminum from the all weld metals to the AISI 310 austenitic stainless steel, as was detected by the sample 1 mainly and especially by identifying the chromium content of the dissimilar alloy and the stainless steel.
       
  • Influence of friction stir welding parameters on metallurgical and
           mechanical properties of dissimilar AA5454–AA7075 aluminum alloys

    • Abstract: Publication date: Available online 18 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Mohamed M. Abd Elnabi, Abou Bakr Elshalakany, M.M. Abdel-Mottaleb, T.A. Osman, A. El Mokadem Friction Stir Welding (FSW) is a solid-state welding process used for welding similar and dissimilar materials. FSW is especially suitable to join Al alloys sheets, and this technique allows different material couples to be welded continuously. In this study dissimilar joints between aluminum alloy (AA5454) and aluminum alloy (AA7075) produced by friction stir welding, to optimize these parameters and determine which of them is significant by using Taguchi L16 optimization method. Seven parameters at two levels were selected in this study. The selected parameters are tool rotational speed, traverse speed, pin profile (based on taper angle), the ratio between shoulder diameter (D) and pin diameter (d) (D/d ratio), tool tilt angle, plunge depth, and base metal location (weld location)). The ultimate tensile strength (UTS) and ductility are considered as the mechanical properties of the dissimilar joints. Then, mathematical models are built for ultimate tensile strength and ductility as a function of significant parameters/interactions using response surface methodology. In addition, the microstructures of the optimum joint and the weakest joint are studied using optical microscopy. The results of this work showed that the rotational speed, traverse speed, D/d ratio and plunge depth are significant parameters in determining UTS (mean, signal to noise ratio (S/N)) at different confidence levels, but pin profile, location of base metal and tool tilt angle are insignificant parameters at any confidence levels. The traverse speed has the highest contribution to the process for UTS about 18.5% and 16.9% for S/N ratio and mean, respectively. The accuracy of the models according to the UTS is 97.6% and 99.5% for mean and S/N ratio, respectively. The maximum joint efficiency, compared to the strength of the AA5454, is 85.3%.
       
  • Influence of plasma nitriding pressure on microabrasive wear resistance of
           a microalloyed steel

    • Abstract: Publication date: Available online 18 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Henver Effgen Ludovico Ramos, Adonias Ribeiro Franco, Estéfano Aparecido Vieira Microalloyed steels have been studied not only by the advent of the pre-salt, but also by the continuous search for improvement of their tribological properties. In this work, the influence of the plasma nitriding (PN) pressure on the nitrided layer formed on top of an API 5L X70 microalloyed steel was studied. PN treatments were carried out using a pulsed plasma reactor at temperatures of 410 °C and 440 °C, in a gas mixture of N2 and H2, for 3 h and under different pressures. Results showed that the pressure has a significant effect on the uniformity and width of the plasma sheath and, consequently, on the structure and thickness of the resulting nitrided layer. It has been observed that higher pressures and temperatures have led to the formation of nitrided layers containing a thinner white layer and without nitride needles. The best wear results were offered by the thicker nitrided layers, besides thinner white layer. This type of structure can be produced when PN treatments are performed using low-width plasma sheaths.
       
  • Innovative polyetherimide and diatomite based composites: influence of the
           diatomite kind and treatment

    • Abstract: Publication date: Available online 18 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Ilaria Cacciotti, Marianna Rinaldi, Josè Fabbrizi, Francesca Nanni In this work innovative composites were developed, using as polymeric matrix polyetherimide (PEI), a high performance thermoplastic, and as natural filler two different kinds of diatomaceous earth, i.e. uncalcined and calcined. The uncalcined powder was amino-functionalised to improve its chemical compatibility with the matrix, whereas the calcined one was submitted to a purification treatment with HCl to remove possible contaminants.Mechanical tests and microstructural characterisation were carried out to evaluate the influence of the filler kind, of its content (i.e. 1–10 wt.%) and of its amino-functionalisation or purification in the case of uncalcined and calcined diatomite, respectively, on the composites performance. The collected results show an increase of Young's modulus with the filler content, particularly in the case of amino-functionalised diatomite, suggesting a good chemical compatibility between filler and matrix. This is substantiated by the scanning electron microscopy (SEM) observation of the fracture surface of samples after tensile test.
       
  • Application of response surface methodology for optimization of hybrid
           friction diffusion bonding of tube-to-tube-sheet connections in coil-wound
           heat exchangers

    • Abstract: Publication date: Available online 17 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Diego Rafael Alba, Arne Roos, Georg Wimmer, Arnaldo Ruben Gonzalez, Stefanie Hanke, Jorge Fernandez dos Santos This study evaluates the application of a new solid state joining process referred to as hybrid friction diffusion bonding. Based on heat processing and pressure, accelerated diffusion joins the materials. In the present study, two aluminum alloys were welded and characterized using leak tightness tests, tensile pull out tests, and metallographic analysis. Response surface methodology was used to optimize the tensile strength of single-hole tube-sheet samples. A Box–Behnken design was selected to evaluate the relations between the important process parameters and the ultimate tensile strength response to obtain optimal welding parameters. The data were analyzed with analysis of variance and were fitted to a second-order polynomial equation. The three-dimensional response surfaces derived from the mathematical models were applied to determine several optimum input parameters conditions. Under these conditions, the experimental ultimate tensile strength value was 202 MPa, which represents 95% of the base material strength. The experimental results obtained under optimum operating conditions were in agreement with the predicted values. Axial force was found to be the most significant factor affecting the joint strength followed by rotational speed. This can be attributed to their influence on the amount of mechanical energy introduced during the process, which is the parameter that primarily determines the joint strength.
       
  • The correlation between structural and reduction kinetics of carbon from
           agricultural waste with hematite

    • Abstract: Publication date: Available online 17 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Nur Hazira Najmi, Nur Farhana M. Yunos, Norinsan Kamil Othman, Muhammad Asri Idris Char conversion by pyrolysis is a promising technique for the production of renewable carbon source. In this study, char generated from agricultural waste (i.e. palm shell) was studied as reductant instead of fossil fuels. The palm shell char was prepared by chemical activation using orthophosphoric acid and pyrolysis under an inert atmosphere at 723 K. The reduction experiment was conducted to understand the reduction of iron oxide with palm shell char where the associated reaction kinetics was elucidated. The reduction conditions were kept constant for 30 min, C/O ratio was 0.6 and particle size
       
  • Full-scale friction welding system for pipeline steels

    • Abstract: Publication date: Available online 17 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Mariane Chludzinski, Rafael Eugenio dos Santos, Daniela Ramminger Pissanti, Filipe Cantelli Kroeff, Fabiano Mattei, Giovani Dalpiaz, Marcelo Torres Piza Paes A fully automatic friction welding system was specially developed for the girth friction welding of pipelines with a diameter of up to 400 mm. The friction welding methods were solid-state joining processes based on the generation of heat through the contact and rotation of an intermediate ring placed between two pipes ends. The thermomechanical process used in this non-fusion method generated different welding zones and microstructures. This resulted in the production of defect-free API 5L X46 welded pipes in less than 5 min. The microhardness profile of the welded joints showed an increase in the intermediate ring hardness. A fracture toughness test and fractographic analyses showed reduced values in the centre of the ring, which were associated with dimples nucleated at small inclusions.
       
  • Intrinsic and extrinsic control of freeze casting

    • Abstract: Publication date: Available online 17 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Isaac Nelson, Steven E. Naleway Freeze casting is a versatile material fabrication process that is known for its ability to create porous scaffold structures from effectively any constituent material. One of its advantages is that a wide variety of alterations to the processing conditions can result in drastic changes to the final micro- and macro-structure of the freeze-cast scaffolds and, therefore, its properties. Here, the authors present a novel view on these numerous control methods, through the concept that each of these methods for controlling freeze casting can either be considered to be an intrinsic or extrinsic control method. Intrinsic control methods act within the freezing process by altering the characteristic repulsive and attractive forces that govern the interactions between the solid loading particles and approaching freezing front during freezing of the slurry. Extrinsic control methods act upon the freeze process through the application of additional forces or energies, often external to the freezing process. This new system of understanding control over freeze casting is presented so as to inspire new work on the advanced control of freeze-cast scaffolds, specific work into extrinsic control methods and the interactions between intrinsic and extrinsic control methods.
       
  • New ergonomic device to improve occupational safety of blasthole drill
           operators

    • Abstract: Publication date: Available online 12 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Edmo da Cunha Rodovalho, Thammiris Mohamad El Hajj, Marcio S. Pastori, Giorgio de Tomi The relationship between mining companies and the society is not limited to the local communities surrounding the operations. The evaluation of the working conditions of the operators of mining equipment is an important dimension of the relationship with the society. Even with the increasing level of automation, there are equipment and operating procedures that have to be adjusted to meet the employees’ capabilities and requirements. For instance, the bit replacement activity requires significant physical work from the employees involved in rock drilling operations. This means that modifications are required in blasthole drills to address the employee's accessibility to bit holders and toolboxes in the drilling platform. However, only a limited number of recent studies have considered ergonomic issues for mining equipments. This research proposes a new ergonomic device for blasthole drills to reduce the ergonomic risk of the operators without affecting the performance. The methods include simulation tools and ergonomic analysis based on the NIOSH Lifting Equation (NLE). The results of the application of the new ergonomic device in all bit replacement tasks have shown risk indexes below the critical limits established by NIOSH. The results have also indicated a performance improvement, with a 60% reduction in bit replacement time.
       
  • Characterization of DLC coatings over nitrided stainless steel with and
           without nitriding pre-treatment using annealing cycles

    • Abstract: Publication date: Available online 12 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Eugenia. L. Dalibón, Thierry Czerwiec, Vladimir J. Trava-Airoldi, Naureen Ghafoor, Lina Rogström, Magnus Odén, Sonia P. Brühl Amorphous hydrogenated diamond-like carbon (DLC) coatings were deposited using plasma assisted chemical vapour deposition (PACVD) on precipitation hardening (PH) stainless steel. Plasma nitriding has been used as pre-treatment to enhance adhesion and mechanical properties. Chemical and mechanical properties of DLC coatings are dependent on the hydrogen content and so on the relation between sp3/sp2 bondings. The bondings and the structure of the DLC film change with temperature. In this work, a study of the thermal degradation and the evolution of the mechanical properties of DLC coatings over PH stainless steel have been carried out, including the effect of an additional nitrided layer.Nitrided and non-nitrided steel samples were subjected to the same coated in the same conditions, and they were submitted to the same thermal cycles, heating from room temperature to 600 °C in several steps.After each cycle, Raman spectra and surface topography measurements were performed and analyzed. Nanohardness measurements and tribological tests, using a pin-on-disc machine, were carried out to analyze variations in the friction coefficient and the wear resistance.The duplex sample, with nitriding as pre-treatment showed a better thermal stability. For duplex sample, the coating properties, such as adhesion, and friction coefficient were sustained after annealing at higher temperatures; whereas it was not the case for only coated sample.
       
  • Multifunctional metal–organic frameworks-based biocatalytic platforms:
           recent developments and future prospects

    • Abstract: Publication date: Available online 11 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Muhammad Bilal, Muhammad Adeel, Tahir Rasheed, Hafiz M.N. Iqbal In recent years, metal–organic frameworks (MOFs) have received accelerating research attention as a versatile carrier and promising bio-immobilization support materials for enzyme immobilization. This is particularly due to their extraordinary structural properties and multi-functionalities, such as surface area, high porosity, tunable topography, crystallinity, electronic and optical properties, thermal/chemical stability and multiple affinities (hydrophobicity and hydrophilicity). Excellent biocatalytic performance, improved stability and repeatability, high loading ability, and greater accessibility to catalytic sites are the key attributes associated with the use of novel MOF–enzyme bio-composites. This review discusses the recent developments in the use of MOFs as immobilization support materials as a platform to engineer different kinds of enzymes with requisite functionalities for biocatalysis applications in different sectors of the modern world. The second part of the review mainly focuses on MOFs-assisted immobilization strategies including surface immobilization, covalent binding, cage inclusion and in situ MOF formation and enzyme immobilization to develop enzyme–MOF bio-catalytic system. The characteristic properties rendering MOFs as interesting matrices for bio-immobilization are also presented following applications of MOFs-immobilized bio-catalyst for catalysis, sensing and detection, and protein digestion. Lastly, the review is wrapped up with conclusions and an outlook in terms of upcoming challenges and prospects for their scale-up applications.
       
  • Dissolution kinetics of hemimorphite in trichloroacetic acid solutions

    • Abstract: Publication date: Available online 11 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Qian Zhang, Shuming Wen, Dandan Wu, Qicheng Feng, Shuo Li In this study, the dissolution kinetics of hemimorphite in the presence of the organic reagent, trichloroacetic acid (TCAA), was investigated. Experimental variables such as reaction temperature (293–323 K), TCAA concentration (0.084–0.184 mol/dm3), particle size (0.081–0.214 mm), and stirring speed (200–650 rpm) were studied to determine the influence on the zinc dissolution rate, and a kinetic model was developed to represent the relationship. The results demonstrated that during the leaching process, zinc was rapidly dissolved in TCAA and the zinc leaching rate increased as a function of increased reaction temperature, TCAA concentration, and stirring speed, and decreased particle size. Among the kinetic models of the porous solids tested, a new variant of the shrinking-core model well described the zinc leaching kinetics. The activation energy was determined to be 54.94 kJ/mol, and the rate of reaction equation [1 − (2/3)x − (1 − x)2/3]2 = [11.24(C)3.80946(PS)−2.00833(SS)1.62147 exp(−54.94/RT)]t was also obtained to describe the process.
       
  • Deep insight into the photoluminescent monocrystalline particles:
           Heat-treatment, structure, mechanisms and mechanics

    • Abstract: Publication date: Available online 11 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Gözde Alkan, HakanYavas, Berfu Göksel, Lidija Mancic, Bernd Friedrich, Olivera Milosevic The red light emitting down-converting Ag@Y2O3:Eu3+ phosphor particles were synthesized by one-step ultrasonic spray pyrolysis and exposed further to the heat treatment at 1000 °C (12 h). A detailed investigation on structural and functional properties of the as-prepared and heat treated particles was conducted in a comparative manner. High-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRPD) and focus ion beam milling (FIB) revealed in a great consistency the poorly crystallized and porous nature of the as-prepared particles. Well-crystallized coarser primary nanocrystals of Y2O3:Eu3+and Ag, which are hierarchically organized in dense spherical Ag@Y2O3:Eu3+ phosphor particles, were obtained through the heat treatment. Along with the change of structural properties, down conversion (red luminescence at 612 nm owing to the Eu3 + 5D0 → 7F2 electric dipole transition) and mechanical endurance were enhanced 4-fold and 5-fold via heat treatment, respectively. This comparative study implies a good correlation between mechanical and luminescence behavior of phosphors, both strongly influenced by the particles structural properties.
       
  • Microscopic investigations on the air-void characteristics of wet-mix
           shotcrete

    • Abstract: Publication date: Available online 11 January 2019Source: Journal of Materials Research and TechnologyAuthor(s): Kyong-Ku Yun, Pangil Choi, Jung Heum Yeon This paper aims to perform microscopic investigations on the air-void characteristics of wet-mix shotcrete before and after the spraying process. Both air-void analysis (AVA) and image analysis (IA) were used to monitor the air-void characteristics of both fresh and hardened mixtures such as air content, spacing factor, and air-void specific surface area. To gain a comprehensive understanding on the air-void characteristics, a total of 28 mixtures were fabricated with different aggregate gradations, slumps, air entrainments, and the types and replacement levels of supplementary cementitious materials (i.e., fly ash, silica fume, metakaolin, and ground-granulated blast furnace slag (GGBFS)). The results have shown that: (1) both pumping and shooting significantly altered the air-void characteristics; (2) the pumping process increased the air content and air-void specific surface area while decreasing the spacing factor; and (3) a decrease in air content and an increase in air-void specific surface area were observed after shooting. In addition, the findings of this study revealed that the air-void characteristics of wet-mix shotcrete were more closely associated with the pumping and shooting operations rather than the mixture characteristics such as aggregate gradation, slump, air entrainment, and mineral admixtures addition.
       
  • The characteristics of μ phase precipitated during 720 °C long-term
           aging in alloy 617B

    • Abstract: Publication date: Available online 29 December 2018Source: Journal of Materials Research and TechnologyAuthor(s): He Jiang, Jianxin Dong, Maicang Zhang In this work, the precipitation of μ phase is detected in alloy 617B during 720 °C aging for 10 000 h. The lattice parameters of μ phase is determined as a = 0.4720–0.4760 nm and c = 2.5394–2.5656 nm in this work. The μ phase in alloy 617B is mainly composed of Mo and Cr, in accompany with Ni and Co. The chemical formula of μ phase in samples aged for 5000 h and 10 000 h is (Ni0.031Co0.084Cr0.885)2.34Mo and (Ni0.030Co0.091Cr0.879)2.30Mo, respectively. The precipitation of μ phase competes with M23C6 carbide for Cr and Mo elements.
       
  • Synthesis of g-C3N4/N-doped CeO2 composite for photocatalytic degradation
           of an herbicide

    • Abstract: Publication date: Available online 28 December 2018Source: Journal of Materials Research and TechnologyAuthor(s): Mohan Kumar Kesarla, Manuel Octavio Fuentez-Torres, Manuel Antonio Alcudia-Ramos, Filiberto Ortiz-Chi, Claudia Guadalupe Espinosa-González, Miguel Aleman, Jose Gilberto Torres-Torres, Srinivas Godavarthi In photocatalysis, surface engineered CeO2 could be vital due to oxygen vacancies arise from multiple valency, i.e. Ce3+ and Ce4+. This study reports photocatalytic properties of g-C3N4/CeO2 composite synthesized by a facile method in the presence of l-arginine. Physicochemical properties of g-C3N4/CeO2 material were analyzed through various characterization techniques such as XRD, UV–Vis, physisorption, etc., and correlated with its photocatalytic activity. Observed bandgap of the synthesized composite material was in the visible region, around 2.8 eV which is less than that of typical ceria, but higher than bandgap of exfoliated g-C3N4. On the further side, N doping into CeO2 was confirmed through XPS analysis. It is estimated that synthesis method aided for the N doping, which further played key role in lowering the bandgap of g-C3N4/CeO2 composite. Finally, Photocatalytic activity of g-C3N4/CeO2 composite was analyzed through degradation of an herbicide i.e. diuron, and the study revealed the good performance of the catalyst.
       
  • Experimental and numerical study on the temperature sensitivity of the
           dynamic recrystallization activation energy and strain rate exponent in
           the JMAK model

    • Abstract: Publication date: Available online 15 December 2018Source: Journal of Materials Research and TechnologyAuthor(s): Missam Irani, Sugun Lim, Mansoo Joun The temperature dependency of the dynamic recrystallization (DRX) activation energy and strain rate exponent, which are major material properties in the Johnson–Mehl–Avrami–Kolmogorov (JMAK) model affecting the DRX phenomenon, are quantitatively presented in experimental and numerical ways. A finite element analysis-based optimization method was used to acquire the material properties of the JMAK model. The first and second stages of a three-stage hot forging process for a bearing outer race were used to obtain and verify all of the material properties, including the DRX activation energy and the strain rate exponent of the JMAK model, which were assumed to be constants or functions of temperature. The predicted grain size after the third stage obtained with the optimized material properties was compared with the experimental values to validate the acquired material properties and reveal the dependence of the two major material properties on temperature. The comparison showed that the difference between the measured and predicted grain sizes was significantly smaller for temperature-dependent material properties, indicating that the DRX activation energy and strain rate exponent are highly temperature-dependent.
       
  • Investigation on the electrospun PVDF/NP-ZnO nanofibers for application in
           environmental energy harvesting

    • Abstract: Publication date: Available online 13 December 2018Source: Journal of Materials Research and TechnologyAuthor(s): Soheil Mansouri, Tahereh Fanaei Sheikholeslami, Amin Behzadmehr PVDF is one of the most widely used dielectric polymers that has four phases. Among them, only its β phase shows piezoelectric property, which is accessible through an electrospinning synthesis method. In this research, a solution of dimethylformamide (DMF) and tetrahydrofuran (THF), with different ratios, and two different polymer concentrations, as well as various ZnO percentages, were used for synthesis of PVDF/NP-ZnO nanofibers composite. The samples that led to the formation of nanofibers were characterized. The results indicate that nanofibers were appropriately formed at lower concentrations of polymer and zinc oxide with equal ratio of the two solvents. To study the effects of synthesis conditions on the morphology and diameter of the nanofibers, the samples were synthesized at different intervals and at different injection rates. The results show that at lower intervals, the injection rate should be reduced to form more uniform nanofibers without nodes and sprays. Finally, flexible piezoelectric nanogenerators were fabricated based on the best samples and were tested under vibrational mechanical forces. The results indicate a maximum output power of 32 nW/cm2. The greater output current and voltage were resulted by using more uniform and stretched nanofibers.
       
  • Dislocation Burgers vector and the Peach–Koehler force: a review

    • Abstract: Publication date: Available online 10 December 2018Source: Journal of Materials Research and TechnologyAuthor(s): Vlado A. Lubarda Different definitions of the Burgers vector and the corresponding construction of the Burgers circuit for dislocation loops and straight dislocations, created by the displacement discontinuity imposed across different surface cuts are reviewed. This is used as a geometric background for the derivation and discussion of the Peach–Koehler expression for the energetic force exerted on a dislocation by different sources of stress. Three approaches were used and compared: (i) the classical virtual work approach of Peach and Koehler, extended to include the changes in size and shape of the dislocation loop; (ii) the potential energy approach which allows the incorporation of the effects of image stresses; and (iii) the approach based on the evaluation of the J-integral. The glide and climb components of the dislocation force are determined and discussed for continuum and lattice dislocations.
       
  • Analysis on surface film formed on high-strength carbon steels in acidic
           phosphate solution and its relationship with localized corrosion in a 3.5%
           NaCl solution

    • Abstract: Publication date: Available online 7 December 2018Source: Journal of Materials Research and TechnologyAuthor(s): Eun Hye Hwang, Jin Sung Park, Hwan Goo Seong, Sung Jin Kim The nature of a passive film formed on high-strength carbon steel and degradation of its passivity in acidic phosphate solutions were characterized by X-ray photoelectron spectroscopy and electrochemical polarization measurements. This study reveals that the steels show typical passivation and localized corrosion behaviors. The passivating film is composed mainly of FePO4·2H2O at a lower potential of 0.4 VSCE, but the major component of the film is changed to γ-Fe2O3 at a higher potential of 1.1 VSCE. At more than 1.5 VSCE, a number of shallow pores and/or pits were observed primarily at coarse-sized second phase particles. The four-point bending test suggested that the pre-existed pits/pores act as stress intensifiers under the subsequently applied tensile loading condition, resulting in higher anodic dissolution rates and lower resistance to stress corrosion cracking (SCC).
       
  • Microstructure and properties of ultrafine-grained W-25 wt.%Cu
           composites doped with CNTs

    • Abstract: Publication date: Available online 7 December 2018Source: Journal of Materials Research and TechnologyAuthor(s): Qiao Zhang, Shuhua Liang, Longchao Zhuo In the present work, the ultrafine-grained W-25 wt.%Cu composites doped with multi-walled carbon nanotubes (CNTs) have been prepared through combined processes of high-energy ball-milling, liquid-phase sintering and infiltration. Furthermore, the microstructure, hardness and electrical conductivity of the ultrafine-grained W-Cu composites doped with different contents of CNTs were investigated. Meanwhile, the wear resistance, compressive performance at different temperatures and arc erosion resistance were evaluated in comparison with the W-Cu composite without CNTs. The results revealed that the hardness, wear resistance, compressive performance and arc erosion resistance of the W-Cu composites doped with CNTs were enhanced dramatically due to the introduction of tungsten carbide phases after sintering and infiltration.
       
  • Synthesis and characterization of molecularly imprinted ferrite
           (SiO2@Fe2O3) nanomaterials for the removal of nickel (Ni2+ ions) from
           aqueous solution

    • Abstract: Publication date: Available online 6 December 2018Source: Journal of Materials Research and TechnologyAuthor(s): Irshad Ahmad, Weqar Ahmad Siddiqui, Tokeer Ahmad, Vasi Uddin Siddiqui The study for the extraction of nickel (Ni2+ ions) from aqueous solution by applying surface modified molecularly imprinted ferrite nanomaterials as an adsorbent. Molecularly imprinted ferrite nanoparticles were synthesized by co-precipitation method, using ferrous and ferric salts in basic medium. Silica coating was done by the Stober method followed sol–gel hydrolysis, using precursor TEOS. Use of Trinitrotoluene (TNT) as a catalyst establishes to be necessary to obtain a proper coating. The particle sizes reveal in the range of 20–24 nm calculated by X-ray diffraction method, which shows the spinal nature of ferrite nanoparticles. Monodispersity of the nanoparticles was also confirmed due to the size distribution of the particles by SEM analysis. Silica coating functionalization with TEOS and adsorbed peak of Ni(II) ion on the surface of ferrite nanocomposites were confirmed by Energy dispersive X-ray (EDX) spectroscopy. The metal adsorption behavior (Ni2+ ion adsorbed on the surface of silica-coated ferrite nanocomposites) characterized by Fourier Transform Infrared spectroscopy (FT-IR). Magnetic property was studied by VSM and the nanocomposites are found to be superparamagnetic at room temperature. Batch experiment conceded to study the adsorption kinetics and the adsorbent stability in the acidic and basic medium was an accessible mechanism of nickel adsorption by ferrite nanocomposites. Adsorption isotherms were well described by Langmuir equations with maximum adsorption capacity (qm) = 2.64 mol/g. The adsorption process establishes to be pH dependent (7.6), adsorbent dose (0.2 g) and equilibrium could be attained within 15 min. All the reaction parameters were considered to complete the adsorption process; it conceded that 94% nickel adsorbed under different optimization conditions. In the study, desorption study, as well as its reusability and recyclability, were accessible indicates that ferrite nanocomposite succeeding adsorption and desorption cycle and retains metal removal capacity until more cycles happened adequately.
       
  • Evaluation of dynamic properties of nano oil palm empty fruit bunch
           filler/epoxy composites

    • Abstract: Publication date: Available online 5 December 2018Source: Journal of Materials Research and TechnologyAuthor(s): N. Saba, M. Jawaid, Othman Y. Alothman, Zeyad Almutairi Cured epoxy resins pretense a constraint for variety of advanced applications due to its notably poor thermal and dynamic (viscoelastic) properties, hence required to minimize their properties prior to their usage. The aim of the present study is to evaluate the effect of nano oil palm empty fruit bunch (OPEFB) fibers at different loadings (1%, 3% and 5%) on the dynamic mechanical properties through dynamic mechanical analysis (DMA) in terms of storage modulus E′, loss modulus E″ and glass transition temperature (Tg) of epoxy composites. Results explored that dynamic properties of the epoxy composites get improved remarkably by the incorporation of nano OPEFB to epoxy composites, while 3% loading displays marked decrease in damping factor with relative to pure epoxy composites and the rest. Overall we perceived that the 3% loading of nano OPEFB filler is the best and optimal to enhance dynamic mechanical properties and to modify the damping factor of the epoxy composites resulting in most promising light weight and thermally stable composite structural materials.
       
  • Synergism between mechanical wear and corrosion on tribocorrosion of a
           titanium alloy in a Ringer solution

    • Abstract: Publication date: Available online 4 December 2018Source: Journal of Materials Research and TechnologyAuthor(s): Danilo Fontes Ferreira, Sérgio Matheus Ale Almeida, Renata Braga Soares, Luciano Juliani, Alexandre Queiroz Bracarense, Vanessa de Freitas Cunha Lins, Rosa Maria Rabelo Junqueira The tribocorrosion behavior of a biocompatible ASTM-F67Gr1 titanium alloy was evaluated. An experimental pin-on-flat reciprocating sliding tribo-electrochemical setup was built which allowed the investigation of tribocorrosion phenomena in an electrolyte of a Ringer solution. Tests were performed at anodic and cathodic potential, and at two values of applied load and sliding speed. Potentiodynamic tests indicated a corrosion potential of −0.368 ± 0.082 VSCE and a passivation range between 0.344 VSCE and 2.932 VSCE was observed. After polarization tests, no pits were identified on the titanium alloy. The volume of worn material was higher at an anodic potential than in a cathodic potential, especially for the condition of the highest applied load and speed. Higher metal losses at a cathodic potential (pure mechanical wear) were observed in conditions of the highest speed. The mass loss due to the corrosion was similar for all conditions, and the synergistic factor was the highest for the condition of the highest applied load and sliding speed.
       
  • Corrosion behavior and surface analysis of 690 MPa-grade offshore steels
           in chloride media

    • Abstract: Publication date: Available online 4 December 2018Source: Journal of Materials Research and TechnologyAuthor(s): Wei-Hsuan Huang, Hung-Wei Yen, Yueh-Lien Lee High-strength low-alloy steels have been used prevalently in marine engineering and the defense industry because of their superior yield strength, toughness, and weldability. Although these materials have excellent mechanical properties, the corrosion resistance of high-strength low-alloy steels is a crucial problem, particularly when they are used in a marine environment. In this study, the corrosion behavior of a newly designed NiCu-containing low-carbon steel (NiCu steel) and conventional S690Q alloy steel (S690Q steel) was investigated and compared. Potentiodynamic polarization results indicated that for NiCu steel, current densities are apparently reduced in the anodic region. Surface analyses indicated that NiCu steel created a thick and uniform inner rust layer after it was immersed in NaCl solution for 7 days. Furthermore, a high-density Cr-rich region was observed in the NiCu inner rust layer after an immersion test. Electrochemical impedance spectroscopy results suggested that NiCu steel exhibits higher corrosion resistance than S690Q steel in NaCl solution.
       
  • Modification and in-place mechanical characteristics research on cement
           mortar with fly ash and lime compound admixture in high chlorine
           environment

    • Abstract: Publication date: Available online 30 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Bingqian Yan, Kouame Joseph Arthur Kouame, Wensheng Lv, Peng Yang, Meifeng Cai As industrial waste, the comprehensive utilization of fly ash involves many fields, among which it is widely used in cement mortar and concrete. As brine water is used in the preparation of filling slurry of Sanshandao Gold Mine, the chloride ions in the slurry have a great negative effect on the strength of the backfill. Therefore, the effects of fly ash and lime on the transport performance and the mechanical properties of cement mortar test blocks were studied by experiment. Based on fly ash XRD analysis, cement mortar block scanning electron microscope test (SEM) and fly ash with various amount and different way of adding test, the mechanism of improving the strength of the cement mortar test block produced by the fly ash and the best mixing amount of the fly ash were determined under the condition of brine water through experiment and theoretical research. Application of fly ash in undersea metal mine is a major breakthrough in the application of filling materials of metal mine undersea metal filling, having great effect on reducing the adverse effects on the strength of the filling body of bittern ions and improving the strength of the filling body.
       
  • Electrochemical investigation on effect of sodium thiosulfate (Na2S2O3)
           and ammonium chloride (NH4Cl) on carbon steel corrosion

    • Abstract: Publication date: Available online 28 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Prince Kumar Baranwal, Prasanna Venkatesh Rajaraman The effect of sodium thiosulfate (Na2S2O3) concentrations (0.01, 0.1 and 1 M) on carbon steel corrosion behavior in 3.75 M ammonium chloride (NH4Cl) solution was investigated. The potentiodynamic polarization results show that the icorr increases from 8.7 × 10−6 A cm−2 to 7.2 × 10−4 A cm−2 when thiosulfate (S2O32−) concentration increases from 0 to 1 M. Electrochemical impedance spectroscopy measurements also mimic the same trend. However, it is also observed that the icorr value starts decreasing when S2O32− concentration equals or exceeds the NH4Cl concentration (Cl−:S2O32− ≥ 1:1) in the electrolyte solution. The polarization behavior and field-emission scanning electron microscopy images reveal that the carbon steel undergoes general corrosion at lower concentrations (0.01 M S2O32− and 0.1 M S2O32−) and, both pitting and general corrosion at higher concentration (1 M S2O32−). Based on the experimental results, the mechanistic reaction pathway, which involves two dissolution paths for carbon steel dissolution is suggested.
       
  • Parametric effects on formability of AA2024-O aluminum alloy sheets in
           single point incremental forming

    • Abstract: Publication date: Available online 28 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Ajay Kumar, Vishal Gulati, Parveen Kumar, Vinay Singh, Brijesh Kumar, Hari Singh Single point incremental forming (SPIF) is a truly die-less forming process which is quite suitable for the batch type and prototype production due to economical tooling cost, shorter lead time and ability to form nonsymmetrical geometries without using expensive dies for manufacturing complex components of sheet metal. This process mainly finds application in the medical sector, aerospace, and automotive industry. Moreover, lack of available information about formability of the process makes it limited for industrial applications. SPIF applicability can be ensured on the industrial scale when appropriate guidelines are highlighted regarding the relation between input parameters and the formability of the process. This paper insights the impact of forming tool shape, tool diameter, wall angle, step size, sheet thickness, and tool rotation on the formability of the AA2024-O aluminum alloy sheet material. Forming depth has been measured by scanning the components using a non-contact 3D scanner. Wall angle and step size have been proved more significant factors which affect the formability greatly.
       
  • Influence of seawater absorption on vibrational and tensile
           characteristics of quasi-isotropic glass/epoxy composites

    • Abstract: Publication date: Available online 28 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Acharya Pavan, Pai Dayananda, Kini M. Vijaya, Sriharsha Hegde, Padmaraj Narampady Hosagade Glass fibre reinforced composites are common structural materials in civil engineering and marine applications. Exposure to moisture is the key challenge for using fibre-reinforced composites in marine structures. This study focuses on preparation of quasi-isotropic E-glass/epoxy laminates with stacking sequence [0°/90°/+45°/−45°]s fabricated using vacuum bagging technique. Ageing studies in artificial seawater was conducted in sub-zero and ambient temperatures for a duration of 3600 h. Moisture absorption behaviour, variation of damping, stiffness properties, and microstructural failure analysis studies were carried out as per ASTM standards. Results indicate that the rate of moisture absorption depends on ageing temperature. In the current study, it is observed that composites aged in ambient temperature absorbed higher amount of moisture than sub-zero temperature aged specimen. Moisture absorption reduced stiffness and natural frequency of quasi-isotropic laminates.
       
  • Biogenic fabrication of gold nanoparticles using Camellia japonica L. leaf
           extract and its biological evaluation

    • Abstract: Publication date: Available online 28 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Tata Sanjay Kanna Sharma, Karuppaiah Selvakumar, Kuo Yuan Hwa, Ponnusamy Sami, Murugan Kumaresan Development of green technique for the fabrication of noble metal nanoparticles is of great importance in order to avoid the usage of toxic chemicals. In this strategy, gold nanoparticles (AuNPs) are synthesized at room temperature by using Camellia japonica leaf extract under room temperature. The successful formation of AuNPs was confirmed by various spectroscopic techniques including UV, FTIR, XRD and SEM studies. The resulting antimicrobial activity of the synthesized AuNPs stabilized in C. japonica is tested against seven different microbial strains such as Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. The present study opens a new window for future synthesis of AuNPs via green technique.
       
  • Effect of titanium (IV) isopropoxide molarity on the crystallinity and
           photocatalytic activity of titanium dioxide thin film deposited via green
           sol–gel route

    • Abstract: Publication date: Available online 27 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Shuhadah A. Yazid, Zulkifli Mohd Rosli, Jariah Mohamad Juoi In this paper, the effect of titanium (IV) isopropoxide TTIP molarity on the crystallinity and TiO2 thin film properties deposited via green sol–gel route was reported. The green sol–gel route is a pioneering approach for eco-friendly coating where solvent is not utilized in the sol formulation. This is in contrast to the common TiO2 sol formulation where solvent is used despite the long term harmful the environment. TiO2 solution with different TTIP molarity of 0.2 M, 0.3 M, 0.4 M and 0.5 M were utilized during coating deposition. Deposition were conducted for ten times using dip coating and treated at 500 °C (1-h). The crystalline phases and phase content were characterized using X-ray diffraction (XRD) and reference intensity ratio (RIR) equation. Crystallites size was obtained by Scherrer's equation while coating morphologies was analyzed using scanning electron microscope (SEM). The photocatalytic activity was conducted by the degradation of methylene blue (MB) towards UV-light and visible light. At higher TTIP molarity (0.5 M), higher crystallinity of mixed anatase (∼17 nm) and rutile (∼29 nm) phases were obtained along with homogeneous coating (cracking and visible pore). Also, higher MB degradation were obtained at UV-light (95%) and visible-light (86%) irradiation. In conclusion, higher TTIP molarity produced TiO2 film with higher crystallinity, small crystallite size, cracking morphology thus contribute good performance in photocatalytic activity. Findings in this work shown that TiO2 thin film deposition is possible conducted without the use of solvent through optimized formulation of only precursor, acid and water. This is beneficial for the environment sustainability.
       
  • Recovery of tungsten from WC–Co hard metal scraps using molten salts
           electrolysis

    • Abstract: Publication date: Available online 27 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Ming Li, Xiaoli Xi, Zuoren Nie, Liwen Ma, Qingqing Liu The recycling of WC–Co hard metal scraps has been taken into consideration in the literature, due to the release of toxic substances and long recovery process. In this study, the recovery of tungsten process, based on the molten salt electrolysis treatment of WC–Co hard metal scraps, was developed. The anode polarization curves were applied to investigate the dissolution of the WC–Co hard metal scrap. Then, the electrochemical behavior of tungsten and cobalt ions dissolved from WC–Co scrap anode, was studied by cyclic voltammetry (CV) and square wave voltammetry (SWV). The results demonstrated that the reduction of tungsten and cobalt ions occurred through a one-step process involving the transfer of two electrons. This process was achieved by the diffusion of tungsten and cobalt ions in the melts. Finally, the parameters, such as the electrolysis current, the electrolysis duration and temperatures, were applied to analyze the effect of different electrolysis conditions on the composition of recycled products. The results demonstrated that the electrolysis current and the electrolysis temperature, compared to electrolysis duration, have significant effects on the selectivity of tungsten recycling. Furthermore, the analysis of cathode products demonstrated that a tungsten powder of approximately 500 nm could be selectively recovered from WC–Co hard metal scrap with the electrolysis condition of 60 mA for 4 h at 1073 K in NaF–KF molten salt.
       
  • Preparation and characterizations of multifunctional PVA/ZnO nanofibers
           composite membranes for surgical gown application

    • Abstract: Publication date: Available online 24 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Muhammad Qamar Khan, Davood Kharaghani, Nazish Nishat, Amir Shahzad, Tanveer Hussain, Zeeshan Khatri, Chunhong Zhu, Ick Soo Kim Herein, we developed the multifunctional; antibacterial, ultraviolet rays (UV) protected and self-cleaning surgical gown by blending of zinc oxide (ZnO) nanoparticles with poly vinyl alcohol (PVA). For this objective, ZnO NPs were blended in three different concentrations: 5 wt%, 7 wt% and 9 wt% in 10 wt% of PVA solution. The morphology of resultant nanofibers was observed under scanning electron microscope and transmission electron microscope and these studies showed the bead-free nanofibers and good dispersion of nanoparticles on nanofibers. Fourier Transform Infrared spectroscope was used for chemical interactions, wide-angle X-ray diffraction (WAXD) was used for analyzing the crystalline structure, agar diffusion plate method was used for antibacterial activity and it showed the effective response of bacteria killing. UV transmission analysis was done by Ultraviolet transmission analyzer, photo-catalytic activity was done by the solar simulator, stress–strain behavior was studied by tensile strength, and water contact angles measurements were done by contact angle meter. On the behalf of characterization results, PVA/ZnO nanofibers were exhibited the desired objectives for the surgical gown. This multifunctional surgical gown is beneficial for medical surgeon against the bacteria, stains and UV blocking to save his/her life.
       
  • Influence of the cold working induced martensite on the electrochemical
           behavior of AISI 304 stainless steel surfaces

    • Abstract: Publication date: Available online 24 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Gleidys Monrrabal, Asuncion Bautista, Susana Guzman, Cristina Gutierrez, Francisco Velasco It is clear that the corrosion resistance of carbon steels decreases as cold working amount increases, but for austenitic stainless steels, the relation between cold-working and corrosion performance is not clear. The electrochemical behavior of AISI 304 stainless steel with 3 different cold working amounts is characterized by Mott–Schottky analysis, OCP records, EIS and cyclic polarization curves. An innovative cell with gel electrolyte is used for an easy study of the deformed surfaces without modifying them. After the polarization tests, the influence of the deformation on the amount of pits and on their morphological characteristics is also analyzed. The microstructural changes caused by cold rolling are studied, and the residual stresses are determined by XRD using the sin2 ψ method. It is proved that AISI 304 stainless steel decreases its pitting resistance in a medium with chlorides when it is subjected to moderate cold rolling, but heavy thickness reduction causes a subsequent recovery of corrosion resistance. The results obtained suggest that this trend is related to changes in the magnitude and type of the stresses (tensile or compressive) on the surface of the material.
       
  • Improvement of formability and tensile mechanical properties of SAE 970X
           steel by controlled rolling process

    • Abstract: Publication date: Available online 23 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Mohammad Masoumi, Edwan Anderson Ariza Echeverri, Cleiton Carvalho Silva, Willys Machado Aguiar, Hamilton Ferreira Gomes de Abreu It is believed that texture, as the preferred crystallographic orientation of microstructural features, causes plastic anisotropy, leading to a decrease in formability. Thus, promoting recrystallization and randomizing crystallographic texture have been the main methods of increasing formability. The aim of the current study was to improve the tensile properties and formability by means of controlling the microstructural features under controlled rolling processes in an SAE 970X steel. The evolution of microstructure, crystallographic orientation, and grain boundary distribution was analyzed by scanning electron microscope, X-ray diffraction, and electron backscatter diffraction. The results of tensile uniaxial tests and equibiaxial tension behaviors showed that the ultrafine ferrite grains oriented along the {011} and {111} planes parallel to the rolling direction, with adequate slip systems accompanied by the dispersion of martensite/austenite (M–A) microconstituents in the ferritic structure, improved the tensile mechanical properties and formability. The sample subjected to isothermal rolling at 850 °C achieved successful results compared to as-received and other controlled rolling methods.
       
  • Orientation controlling of Ni-based single-crystal superalloy by a novel
           method: grain selection assisted by un-melted reused seed

    • Abstract: Publication date: Available online 23 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Wenchao Yang, Songsong Hu, Miao Huo, Dejian Sun, Jun Zhang, Lin Liu A new grain selection method assisted by un-melted short seed was proposed to control the primary and secondary orientations of Ni-based single-crystal superalloy. The results showed that the use of short seeds could effectively avoid the formation of the melt back mush zone. Although a few stray grains were formed at the upper of the short seed because Al2O3 and SiO2 particles might act as nucleation sites, an expected grain with the smallest misorientation was predominant in starter block. Finally, the orientations of the Ni-based single crystal superalloy component could be not only well controlled with a smaller misorientation about 2.1°, but also a paper-thin substance mixed Al2O3 and SiO2 particles was partly covered with the surface of the un-melted short seed, which made this seed convenient to separate and reuse resulting in the reduction of cost.
       
  • Two ditetrazole derivatives as effective inhibitors for the corrosion of
           steel in CH3COOH solution

    • Abstract: Publication date: Available online 23 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Shuduan Deng, Xianghong Li, Guanben Du The inhibition performance of two ditetrazole derivatives of blue tetrazolium (BT) and nitrotetrazolium blue chloride (NTBC) on cold rolled steel (CRS) in 2.5 M CH3COOH solution was studied by weight loss, electrochemical techniques and scanning electron microscope (SEM). Quantum chemical calculations of BT2+ and NTB2+ were performed to theoretically investigate the adsorption mechanism. The results show that both BT and NTBC behave as effective inhibitors, and their maximum inhibition efficiency values are higher than 92% at 0.20 mM. The inhibition follows the order of NTBC > BT. The adsorption of either BT or NTBC on steel surface follows Langmuir isotherm. BT and NTBC can be arranged as mixed-type inhibitors. The presence of BT or NTBC increases the charge transfer resistance, and decreases the corrosion degree of steel surface in CH3COOH. The adsorption centers are mainly focused on two tetrazole rings as well as the linkers of two benzene rings.
       
  • Quantitative X-ray microtomography technique to evaluate high-temperature
           transient diffusion of Iron diffusants in high alumina-silicate porous
           refractory media

    • Abstract: Publication date: Available online 19 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Carlos Eduardo Guedes Catunda, Roberto Ribeiro de Avillez, Marcos Henrique de Pinho Mauricio Diffusion tests were performed with solid diffusants of Iron oxides in contact with porous silico-aluminous refractory castables in high-temperature conditions. A non-destructive X-ray computer microtomography technique with digital 3D reconstruction (3DμCT) was used for spatial monitoring the diffusion into the media. A particle tracking (PT) method was applied to evaluate diffusion through porous materials and to quantify its diffusive properties based on 3D images over time. The influence of temperature was examined in the range from 1100 °C to 1300 °C. Each sample was heat treated for 100 h in the investigated temperature. The normalized concentration of diffusants as a function of the penetration was obtained by 3DμCT images and compared with the concentration profile determined by elementary microanalysis with energy dispersive spectroscopy and surface chemical mapping (MAP/EDS). Thus, the diffusivity of the porous media was quantified from the experimental data. It was observed a variation less than 3.52% between the MAP/EDS and 3DμCT, i.e., between the destructive and non-destructive methods, suggesting that the 3DμCT method may be extended to other media and diffusants.
       
  • Physical simulation as a tool to understand friction stir processed X80
           pipeline steel plate complex microstructures

    • Abstract: Publication date: Available online 17 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Julian Avila, Julian Escobar, Barbara Cunha, William Magalhães, Paulo Mei, Johnnatan Rodriguez, Haroldo Pinto, Antonio Ramirez The thermal cycles associated to friction stir welding and processing produce a wide range of microstructures, resulting in different mechanical behaviors along the weld. Most research efforts have focused on the development of welding parameters to obtain sound welds, yet there is still an opportunity for performance improvement based on the understanding of how microstructures are produced. This work explored the different microstructures obtained after physical simulation of an X80 pipeline steel, as a function of the cooling rate and the isothermal transformation temperature. The aim was to study the development of complex mixed microstructures under controlled conditions, in order to compare them to the ones obtained after friction stir processing. As result of the continuous cooling and isothermal thermal simulations, intermediated and high cooling rates, the microstructures matched with those found at the processed plates. These results might help developing a better cooling control after welding.
       
  • Flotation studies of fluorite and barite with sodium petroleum sulfonate
           and sodium hexametaphosphate

    • Abstract: Publication date: Available online 17 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Zhijie Chen, Zijie Ren, Huimin Gao, Renji Zheng, Yulin Jin, Chunge Niu The development of new collectors to separate fluorite from barite is urgently needed in mineral processing. In this study, the flotation behavior of fluorite and barite was studied using sodium petroleum sulfonate (SPS) as a collector with sodium hexametaphosphate (SHMP) as a depressant. The performance of reagents on minerals was interpreted by infrared spectroscopic analysis and zeta potential measurement. The flotation results showed that SPS performed well in a wide pH region (7–11) even at a low temperature (5 °C), while the flotability of fluorite and barite were almost the same. At pH 11, the presence of SHMP obviously depressed fluorite rather than barite and SHMP exhibited good selective inhibition to fluorite. Fourier-transform infrared spectra and zeta potential results showed that: (1) SPS can adsorb on fluorite and barite surfaces and (2) SHMP had little effect on the adsorption of SPS on a barite surface, although it interfered with the adsorption of SPS on a fluorite surface through strong adsorption.
       
  • Zn–Al-based layered double hydroxides (LDH) active structures for
           dental restorative materials

    • Abstract: Publication date: Available online 16 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Marcela Piassi Bernardo, Caue Ribeiro The development of smart dental materials able to react to its environment and release remineralizing ions is attractive point of research. The phosphate interaction with Zn–Al layered double hydroxide was evaluated by the reconstruction method, at 300 °C and 600 °C. In a general way, thermal stable zinc-phosphate compounds are formed with the increase of the phosphate concentration. To assess the potential to act as bioactive dental restorative materials, phosphate-loaded samples were incorporated on photopolymerizable dental resin (Fill Magic, Coltene) at 2.5% and 4% (m/m) evaluating the phosphate release at artificial saliva medium. After 58 days, the materials showed a useful continuous release of phosphate which in conjunct with other mineralizing elements, could contribute to remineralization of dental tissues and protection against caries and other dental health problems.
       
  • Bioinspired composite segmented armour: Numerical simulations

    • Abstract: Publication date: Available online 16 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Pedro Miranda, Antonia Pajares, Marc A. Meyers Nature has evolved ingenious armour designs, like the flexible carapaces of armadillo and boxfish consisting of hexagonal segments connected by collagen fibres, that serve as bioinspiration for modern ballistic armours. Here, Finite element modelling (FEM) used to analyze the effect of scale geometry and other impact parameters on the ballistic protection provided by a bioinspired segmented ceramic armour. For this purpose, the impact of cylindrical fragment simulating projectiles (FSPs) onto alumina-epoxy non-overlapping scaled plates was simulated. Scale geometrical parameters (size, thickness and shape) and impact conditions (FSP diameter, speed, location) are varied and the amount of damage produced in the ceramic tiles and the final residual velocity of the FSP after the impact are evaluated. It is found that segmentation drastically reduces the size of the damaged area without significantly reducing the ballistic protection in centred impact, provided the tile size is kept over a critical value. Such critical tile size (∼20 mm, inscribed diameter, for impacts at 650 m/s) is independent of the scale thickness, but decreases with projectile speed, although never below the diameter of the projectile. Off-centred impacts reduce the ballistic protection and increase the damaged area, but this can be minimized with an appropriate tile shape. In this sense and in agreement with the natural hexagonal tiles of the boxfish and armadillo, hexagonal scales are found to be optimal, exhibiting a variation of ballistic protection—measured as reduction of projectile speed—with impact location under 12%. Design guidelines for the fabrication of segmented protection systems are proposed in the light of these numerical results.
       
  • Applicability of shear punch testing to the evaluation of hot tensile
           deformation parameters and constitutive analyses

    • Abstract: Publication date: Available online 12 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Mohammad Javad Esfandyarpour, Reza Alizadeh, Reza Mahmudi Shear punch testing (SPT) was used to evaluate hot deformation constitutive parameters, and the results were compared with those of the conventional uniaxial tensile testing (UTT) method. Both tests were performed on a rolled Sn–5Sb alloy, as a model material, in the temperature range of 298–400 K and under strain rates in the range of 5 × 10–4 to 1 × 10–2 s–1. Reasonable agreement was found between the parameters obtained in both deformation modes for the power-law, exponential, and hyperbolic sine constitutive equations. The obtained stress exponents and activation energy values in shear deformation were almost the same as those found in the tensile deformation. Therefore, it can be concluded that the data provided by the easy-to-perform SPT can be used for the prediction of constitutive equations as well as deformation mechanisms of the material in the tensile deformation mode. Based on the power-law stress exponents in the range of 4.5–7.0 and activation energy values of about 54–59 kJ mol–1, dislocation climb mechanism controlled by the lattice diffusion could be suggested as the main controlling mechanism of the deformation of the alloy in both deformation modes.
       
  • Blocking of factorial experiments in galvanized wire zinc weight test

    • Abstract: Publication date: Available online 10 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Lucas Sonego Fernandes, José Demétrio Leite de Figueiredo, Oscar Olímpio de Araújo Filho, Edval Gonçalves de Araújo Industrial competitivity has been, in last years, the business stress aggravated by the strong advance of globalization, with huge effects in commercial world. The run for lower operational costs and for the resources optimization forces the serious organizations to use statistical methods to guarantee the most different development and improvement projects in its processes, for the effect of an error in these areas can lead to significant losses of company image, revenue and market share. The objective of this paper is to contextualize the factorial experiments with blocking method in industrial applications, giving practical examples for method applications and, with a real example, to apply the blocking tool in order to evidentiate its benefits.
       
  • Mechanical and moisture diffusion behaviour of hybrid Kevlar/Cocos
           nucifera sheath reinforced epoxy composites

    • Abstract: Publication date: Available online 9 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): J. Naveen, M. Jawaid, E.S. Zainudin, M.T.H. Sultan, R. Yahaya The aim of this research is partial replacement of plain woven Kevlar 29(K) with naturally woven cocous nucifera sheath (CS) waste. Laminated K/CS reinforced epoxy hybrid composites were fabricated by hand lay-up method followed by hot compression moulding with 105 °C temperature at 275 bar pressure for 1 h. The total fibre loading of the hybrid composite was maintained 45 wt.% and the ratio of Kevlar and Cocous nucifera sheath varies in weight fraction of 100/0, 75/25, 50/50, 25/75, and 0/100. Mechanical (tensile, flexural, impact), moisture diffusion and morphological behaviour of the laminated composites were evaluated. The results showed that the hybrid composites (75/25) declined the tensile strength by 19% compared to Kevlar fabric reinforced epoxy composites. But, the hybrid composites (75/25) exhibited highest flexural strength (175 MPa) and flexural modulus (18 GPa) than pure Kevlar reinforced epoxy composites. Moreover, the impact toughness of hybrid composites (86 kJ/m2) at 75/25 wt.% showed good agreement with the pure Kevlar fabric reinforced polymer composites (90 kJ/m2). From the moisture diffusion analysis, hybrid composites (75/25) exhibited better moisture resistance. Statistical analysis of the results has been carried out using one way-ANOVA (analysis of variance) and it shows that there is a statically significant difference between the obtained mechanical properties of the laminated composites. Morphology of the tensile fractured laminates showed the delamination's, matrix cracking and fibre/matrix adhesion. From the results, it has been concluded that naturally woven Cocos nucifera sheath has the potential to replace Kevlar fabric in the polymer composites exclusively for defence applications.
       
  • Structural and phase changes under electropulse treatment of
           fatigue-loaded titanium alloy VT1-0

    • Abstract: Publication date: Available online 9 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Sergey Konovalov, Irina Komissarova, Yurii Ivanov, Victor Gromov, Dmitry Kosinov The effect of electropulse treatment (EPT) of titanium alloy VT1-0 on the change of its fatigue life, structure and phase composition has been investigated. The study has shown that EPT improves the fatigue life by 1.3 times. Methods of TEM were used to analyze changes of the structure and phase composition of samples subjected to EPT and endurance testing. In the process of fatigue tests involving cantilever bending, a grain and sub-grain structure is formed in the surface of commercially pure titanium. The study has disclosed that the surface layer of the material has a multi-phase structure. Nano-crystal grains are formed by α-titanium. Oxide phase of titanium has been revealed, which is located along the crystallite boundaries of α-titanium. Particles of oxide phase have been identified exclusively in the top nano-structured layer. In the rest of the sample there are no particles of this phase. EPT causes dimensional changes of oxide phase particles and many-fold dimensional changes of crystallites in the surface layer. Owing to this treatment there are less internal stress concentrators in the surface layer of the material, which results, therefore, in cut down on probable spots of crack origination.
       
  • Deformation behavior and anisotropic response of 2060 Al-Cu-Li alloy:
           experimental investigation and computational homogenization-based crystal
           plasticity modeling

    • Abstract: Publication date: Available online 9 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Ali Abd El-Aty, Shi-Hong Zhang, Yong Xu, Sangyul Ha Since AA2060-T8 was launched the past few years, it was crucial to understand the deformation behavior and to establish a multi-scale model that can link the microstructural state of this alloy with its mechanical behavior. Thus, a computational homogenization-based crystal plasticity modeling was proposed to predict the deformation behavior and capture the anisotropic response of AA2060-T8 at different deformation conditions. Uniaxial tensile tests were accomplished at room temperature and strain rates of 0.001 and 0.1 s−1 using samples with different fiber orientations to experimentally investigate the deformation behavior and anisotropic response of AA2060-T8. Thereafter, to clarify the details of the in-grain deformation features, a representative volume element was established to describe the real microstructure of AA2060-T8 in which each grain was discretized using many finite elements. Afterwards, a dislocation density-based crystal plasticity model was developed to describe the behavior of grains and simulate the plastic deformation of AA2060-T8. The material parameters utilized in the crystal plasticity model was determined from the stress–strain curves of the samples tested at loading direction of 30° with respect to rolling direction and strain rate of 0.001 s−1. Additionally, a periodic boundary condition was modified to consider both geometrical and deformation induced anisotropy. The achieved results from the proposed computational homogenization method are in remarkable agreement with that obtained from experimental work. This means that the proposed computational homogenization method is able to predict the deformation behavior and capture the anisotropic response of AA2060-T8 at various deformation conditions.
       
  • Multiphase aluminum A356 foam formation process simulation using lattice
           Boltzmann method

    • Abstract: Publication date: Available online 9 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Mojtaba Barzegari, Hossein Bayani, Seyyed Mohammad Hosein Mirbagheri, Hasan Shetabivash Shan–Chen model is a numerical scheme to simulate multiphase fluid flows using lattice Boltzmann approach. The original Shan–Chen model suffers from inability to accurately predict behavior of air bubbles interacting in a non-aqueous fluid. In the present study, we extended the Shan–Chen model to take the effect of the attraction–repulsion barriers among bubbles in to account. The proposed model corrects the interaction and coalescence criterion of the original Shan–Chen scheme in order to have a more accurate simulation of bubbles morphology in a metal foam. The model is based on forming a thin film (narrow channel) between merging bubbles during growth. Rupturing of the film occurs when an oscillation in velocity and pressure arises inside the channel followed by merging of the bubbles. Comparing numerical results obtained from proposed model with metallography images for aluminum A356 demonstrated a good consistency in mean bubble size and bubbles distribution.
       
  • Wetting behavior of Sn–Ag–Cu and Sn–Bi–X alloys: insights into
           factors affecting cooling rate

    • Abstract: Publication date: Available online 5 November 2018Source: Journal of Materials Research and TechnologyAuthor(s): Bismarck L. Silva, Amauri Garcia, José E. Spinelli Based on two experimental approaches: transient directional solidification and drop shape analyses, the measurements of cooling rates and contact angles (θ) of several solders of interest became practical. Three Sn–0.7Cu–(1; 2 and 3Ag) and four Sn–34Bi–(0Cu; 0.1Cu; 0.7Cu; 2Ag) alloys are investigated to determine their wetting behavior, compare to each other and bring to light their ability (or not) to control the initial cooling rate. In the case of SAC alloys, increase in Ag means decrease in both θ and cooling rate. An opposite correlation between cooling rate and θ is observed when Sn–34Bi and the Sn–34Bi–0.1Cu alloys are compared.
       
  • Effect of holding time, thickness and heat treatment on microstructure and
           mechanical properties of compacted graphite cast iron

    • Abstract: Publication date: Available online 29 October 2018Source: Journal of Materials Research and TechnologyAuthor(s): Hassan Megahed, Emad El-Kashif, Ahmed Y. Shash, Mahmoud A. Essam The effect of holding time, thickness and annealing heat treatment on the microstructure and some mechanical properties of compacted graphite iron (CGI) are studied. Samples of CGI are produced in Helwan factory for casting by using GGG 70 as base metal in a medium frequency induction furnace. The mechanical properties (tensile strength, and hardness) of the as-cast and after heat treatment samples are determined and the microstructure of the samples is examined using optical microscope. The results show that the mechanical properties and microstructure of CGI depend on holding time, thickness and annealing heat treatment; it is found that increasing the holding time from 10 min to 17 min results in lowering the Mg content from 0.031% to 0.021% and as a result lower nodularity was obtained. Lowering the thickness from 20 mm to 5 mm increases the tendency of dendritic structure as a result of increasing the cooling rate. The annealed samples with mainly ferritic matrix gave the lowest tensile strength and hardness value compared with the as-cast conditions.
       
  • Hot deformation and processing maps of Al–Zn–Mg–Cu alloy under
           coupling-stirring casting

    • Abstract: Publication date: Available online 25 October 2018Source: Journal of Materials Research and TechnologyAuthor(s): Haijun Wang, Chao Wang, Yang Mo, Hui Wang, Jun Xu Compression tests of direct-chill (DC) casting and coupling-stirring (CS) casting Al–Zn–Mg–Cu alloy have been performed in the strain rate range from 0.01 s−1 to 10 s−1 and the temperature range from 320 °C to 480 °C. The effects of DC casting on the processing map, flow behavior and deformation kinetic have been discussed. The result shows that the uniformity of the critical stress, the peak stress and the steady-state stress have been improved and the flow stress has been decreased significantly using the coupling stirring. The processing maps shown that the suitable deformation condition for the DC casting alloy is 0.01–0.1 s−1 and 380–480 °C, and the suitable deformation condition for the CS casting alloy is 0.01–0.05 s−1 and 320–480 °C and 0.05–0.5 s−1 and 400–480 °C. The activation energies at the deterministic domains of the DC casting alloy and CS casting alloy are 210 kJ/mol and 185 kJ/mol, respectively.
       
  • Assessment of iron ore pellets production using two charcoals with
           different content of materials volatile replacing partially anthracite
           fines

    • Abstract: Publication date: Available online 25 October 2018Source: Journal of Materials Research and TechnologyAuthor(s): Gustavo Eduardo Praes, José Dimas de Arruda, Leandro Rocha Lemos, Roberto Parreiras Tavares Iron ore pelletizing plant consumes coal, pet coke, oil and natural gas to get the required chemistry, physical and metallurgical properties for iron ore pellets, consumed in steel industry. Tests were carried out to burn green iron ore pellets, which consumed natural gas; coal (anthracite fines) and two different eucalyptus charcoal (replacing the anthracite fines partially) with two different range of volatile materials. First charcoal with a volatile range of 20.3–25.98% and, a second one varying from 9.4 to 11.1%. Based on fixed carbon (10 kg/1 ton of pellets) content in green mixture, several tests were done to replace approximately 0.0, 7.5, 10.0 and 35.0% of anthracite fines by the two different charcoals, each turn with one charcoal, at the end both charcoals were tested and replaced the anthracite fines in the same amount of fixed carbon content. The “zero” replacement was the standard pellet trial, produced only with anthracite fines. Experiments were performed on a pilot scale plant using a mixer for green mixture, pelletizing disk, and a reactor of “pot grate” type for burning green pellets, that reactor simulated the traveling grate indurating machine. After burning, samples were collected to undergo physical tests, such as: tumble, abrasion and crushing strength. It was possible to replace 7.5% of anthracite fines by the two eucalyptus charcoal. Still 10.0% of replacement of anthracite fines was possible with the charcoal with lower volatile matter.
       
  • Preparation and characterization of chitosan/clay composite for direct
           Rose FRN dye removal from aqueous media: comparison of linear and
           non-linear regression methods

    • Abstract: Publication date: Available online 22 October 2018Source: Journal of Materials Research and TechnologyAuthor(s): Abida Kausar, Kashaf Naeem, Muhammad Tariq, Zill-i-Huma Nazli, Haq Nawaz Bhatti, Farhat Jubeen, Arif Nazir, Munawar Iqbal In the present study, sorption efficacy of chitosan (β-(1→4)-linked d-glucosamine and N-acetyl-d-glucosamine) composite for synthetic direct Rose FRN dye removal from aqueous media was investigated. Chitosan and clay were subjected to chemical modifications to prepare chitosan/clay composite. Batch sorption affecting parameters like pH, composite dose, volume, initial dye concentration, time and temperature were optimized. Maximum sorption capacity (17.18 mg/g) was found within first 40 min of contact. Point of zero charge was found to be 7.0. Linearized and non-linearized regression forms of pseudo 1st and 2nd order kinetic models were used to predict the nature of rate limiting steps involved in the sorption process. Sorption equilibrium data was revealed by applying linear and non-linear equilibrium Langmuir, Freundlich and Redlich–Peterson isotherm models. Calculated values of thermodynamic factors showed that sorption process is exothermic, spontaneous and feasible. Desorption studies were performed for the regeneration of chitosan/clay composite by using different eluting agents. The synthesized composite were characterized by X-ray diffraction (XRD), surface analysis (Brunauer, Emmett and Teller: BET), scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The developed method was also applied on the real textile effluent for the efficient removal of dyes.
       
  • Effect of multi-walled carbon nanotubes (MWCNTs) on the strength
           development of cementitious materials

    • Abstract: Publication date: Available online 22 October 2018Source: Journal of Materials Research and TechnologyAuthor(s): Ali Naqi, Naseem Abbas, Nida Zahra, Abasal Hussain, Syed Qasim Shabbir The proposed study aimed to investigate the potential use of pristine multi-walled carbon nanotubes (MWCNTs) as nano reinforcement in enhancing mechanical properties of hybrid MWCNT/silica fume cement composites. Dispersion of MWCNTs was facilitated utilizing very fine particles of silica fume which also helped in an improved interfacial bond between MWCNTs and the cement matrix. The MWCNTs dispersion within the hardened cement matrix was qualitatively assessed by Field Emission Scanning Electron Microscope (FESEM) analysis. It was also observed that addition of MWCNTs accelerated the hydration process. The test results showed an increment in compressive strength by 12.4% and reduction in autogenous shrinkage by 8.5% for hybrid MWCNT/silica fume cement composites containing 0.01% MWCNTs (by wt. of binder). However, higher additions (greater than 0.03%) of MWCNTs appeared to have adverse effects on specimens. It was found that properly dispersed MWCNTs filled the fine pores in the cement matrix by providing an additional nucleation site for the formation of calcium silicate hydrate (C-S-H) that results in a denser microstructure, which in turn enhanced the strengths and limited the autogenous shrinkage.
       
  • Modification of optical and electrical properties of nanocrystalline
           VO2·0.5 H2O/ZrV2O7: influence of Cs, Cr and Ga doping

    • Abstract: Publication date: Available online 22 October 2018Source: Journal of Materials Research and TechnologyAuthor(s): Marwa Elkady, Hesham Hamad, Noha El Essawy A facile and economical route has been demonstrated for large-scale synthesis of nano VO2·0.5 H2O/ZrV2O7 and it is doping with Cs, Cr and Ga using combined precipitation-hydrothermal that followed by a gentle heating at low temperature. The growth mechanism of doping is discussed and investigated by XRD, SEM, TEM, Raman, TGA, DSC, and UV–vis spectroscopy. The band gap is enhanced with doping. The results show that the all composites have a negative thermal coefficient in the range 25–100 °C while it has a positive thermal coefficient in the range 100–300 °C. Also, Cs doped has increase in conductivity as compared to Cr doped which may be due to the enhancement of oxygen vacancies as resulted from addition of low valence cations. Doping with Cr or Cs show the contribution of grain and grain boundary properties, respectively, while the doping with Ga shows the insulating behavior.
       
  • The effects of lubricants on temperature distribution of 6063 aluminium
           alloy during backward cup extrusion process

    • Abstract: Publication date: Available online 22 October 2018Source: Journal of Materials Research and TechnologyAuthor(s): Omolayo M. Ikumapayi, Sunday T. Oyinbo, Ojo P. Bodunde, Sunday A. Afolalu, Imhade P. Okokpujie, Esther T. Akinlabi Backward extrusion has received several applications in the production and manufacturing sectors, most importantly in the bulk forming processes and various researchers have carried out several studies about backward extrusion processes in the time past varying from experimental, theoretical, empirical, analytical to numerical methods in order to analyze and optimize it. In this present investigation, backward cup extrusion of AA6063 was successfully carried out experimentally and theoretically using tropical coconut oil and castor oil as lubricants. The experiment was also carried out without lubrication. With the different lubricating conditions, the strain rate was varied at 1.5 × 10−3 s−1, 2.0 × 10−3 s−1, 2.5 × 10−3 s−1 and 3.0 × 10−3 s−1 respectively. A numerical analysis using DEFORM 3D software for backward cup extrusion at strain rates of 2.0 × 10−3 s−1 and 2.5 × 10−3 s−1 were then performed to determine optimum lubricated condition and temperature distribution during the deformation. It was found that the temperature increased with increasing strain rates. At a higher strain rate, the temperature of both punch and lower die also increased. The highest temperature was observed when lubricated with tropical coconut oil at a strain rate of 3.0 × 10−3 s−1 which was observed to be above 33 °C when compared to other lubricants. The punch temperature showed a higher temperature compared to the lower die temperature in all cases. The extrusion load–stroke curve of the simulation result was consistent with the experimental results.
       
  • Mathematical model for the temperature profiles of steel pipes quenched by
           water cooling rings

    • Abstract: Publication date: Available online 21 October 2018Source: Journal of Materials Research and TechnologyAuthor(s): Daniela Fátima Gomes, Roberto Parreiras Tavares, Bernardo Martins Braga The quenching process is one of the most important steps in steel heat treatment and has a significant impact on the quality of the product. In systems with water cooling rings, there are several operational parameters that affect the performance of the heat treatment, such as the longitudinal and angular speeds of the pipe, the water flow rate and pressure. Mathematical models have been developed to predict the temperature profile in the steel pipe, to investigate the causes of defect formation and to allow a better control of the cooling conditions. In the present work, two-dimensional (2D) and tridimensional (3D) models were developed to simulate the heat transfer during the cooling of the pipe. The models were verified, and the tridimensional model was validated by industrial tests. Several simulations have been carried out to compare the 2D and 3D approaches and the effect of the angular speed of the pipe was investigated. The results indicated that the temperatures calculated using the 2D and 3D models are different. It was demonstrated that an increase in the rotation speed of the pipe leads to a more uniform temperature distribution. However, for rotation speeds superior to 6 rad/s, no significative effect in the temperature profile is obtained by increasing the speed of rotation.
       
  • Structural investigation and enhancement of optical, electrical and
           thermal properties of poly (vinyl chloride-co-vinyl
           acetate-co-2-hydroxypropyl acrylate)/graphene oxide nanocomposites

    • Abstract: Publication date: Available online 19 October 2018Source: Journal of Materials Research and TechnologyAuthor(s): Ahmed Y. Yassin, Abdel-Raouf Mohamed, Elmetwaly M. Abdelrazek, Muhamed A. Morsi, Amr M. Abdelghany Different concentrations of graphene oxide (GO) were successfully embedded into poly (vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate) (PVVH) copolymer. The composites obtained were characterized using XRD, FT-IR, SEM and UV/Vis techniques, in addition to investigating their electrical properties. XRD results showed the predominance of the amorphous phase inside the prepared samples. The main characteristic peaks of the used materials were observed in FT-IR spectra with changes in their intensities and/or their positions, confirming the successful complexation and strong interaction between GO and PVVH. A bathochromic shift in the main absorption sharp edge was detected in UV/Vis spectra. Additionally, the two peaks at 214 and 280 nm were ascribed to n→π* and π→π* transitions, respectively. Both optical energy gap and refractive index were calculated in terms of UV/Vis absorption spectra using Mott–Davis model and Dimitrov–Sakka equation. The thermal behavior of the current samples was carefully investigated by employing TGA. Moreover, the activation energy was studied using Coats-Redfern and Broido models. The homogeneous dispersion of GO has contributed to the significant increase in the electrical conductivity as well as improving thermal stability of the PVVH-based nanocomposites. The experimental results obtained for the current system promote these nanocomposites for use in optoelectronic applications.
       
  • The influence of carbon nanotube addition on the phase composition,
           microstructure and mechanical properties of 316L stainless steel
           consolidated by spark plasma sintering

    • Abstract: Publication date: Available online 19 October 2018Source: Journal of Materials Research and TechnologyAuthor(s): Péter Jenei, Csaba Balázsi, Ákos Horváth, Katalin Balázsi, Jenő Gubicza Composites of 316L steel and carbon nanotubes (CNTs) were produced by powder metallurgy using high energy milling and spark plasma sintering. The influence of CNT content on the microstructure and the mechanical properties was studied, therefore in addition to the composite samples containing 1 and 3 wt.% CNTs, a 316L specimen without CNTs was also processed. It was found that the CNT addition resulted in a smaller grain size and a higher dislocation density in the matrix. The fraction of the Fe3C phase formed due to the CNT addition increased with increasing the CNT content. The smaller grain size, the higher dislocation density and the larger fraction of the Fe3C phase led to a higher hardness in the samples containing CNTs. At the same time, the strength determined by bending was reduced, most probably due to the weak bonding between the 316L grains and the CNTs.
       
  • Manufacture of absorber fins for solar collector using incremental sheet
           forming

    • Abstract: Publication date: Available online 19 October 2018Source: Journal of Materials Research and TechnologyAuthor(s): Rafael Gustavo Schreiber, Lirio Schaeffer This article sets out to present a new manufacturing process applied to create absorber fins for solar collectors. Using Incremental Sheet Forming, a flexible process that can be performed at a CNC production center, it is possible to make prototypes of absorber fins with collector riser fittings, which also enables the development of new fin designs using different materials in a wide range of thicknesses. This article analyzes parameters of the Two Point Incremental Forming process, with a partial die for solar collector absorber fin manufacturing using a 1 mm thick aluminum AA1200-H14 in order to determine the influence of the step down and the tool's rotation speed on the sheet's formability, being thus able to determine the most appropriate combination of these parameters to obtain a process with the greatest quality and productivity. A series of 16 experiments was proposed to manufacture a small absorber fin comparing the rotation speed values of S = 50, 200, 400, and 800 rpm, with step down values of Δz = 2, 1, 0.5, and 0.2 mm. The feed rate value was kept at F = 250 mm/min, and each experiment was performed until the first crack occurred in the sheet. In this study, it was possible to indicate the feasibility of the process under more efficient parameters for manufacturing absorber fins using the step down of 2 mm and the rotation speed of 50 rpm.
       
 
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