Subjects -> MANUFACTURING AND TECHNOLOGY (Total: 363 journals)
    - CERAMICS, GLASS AND POTTERY (31 journals)
    - MACHINERY (34 journals)
    - MANUFACTURING AND TECHNOLOGY (223 journals)
    - METROLOGY AND STANDARDIZATION (6 journals)
    - PACKAGING (19 journals)
    - PAINTS AND PROTECTIVE COATINGS (4 journals)
    - PLASTICS (42 journals)
    - RUBBER (4 journals)

CERAMICS, GLASS AND POTTERY (31 journals)

Showing 1 - 29 of 29 Journals sorted alphabetically
Advances in Applied Ceramics     Hybrid Journal   (Followers: 4)
Boletín de la Sociedad Española de Cerámica y Vidrio     Open Access   (Followers: 1)
Ceramics     Open Access  
Ceramics International     Hybrid Journal   (Followers: 26)
CeROArt     Open Access   (Followers: 1)
Challenging Glass Conference Proceedings     Open Access   (Followers: 1)
Crystal Growth & Design     Hybrid Journal   (Followers: 13)
Glass and Ceramics     Hybrid Journal   (Followers: 3)
Glass Technology - European Journal of Glass Science and Technology Part A     Full-text available via subscription   (Followers: 1)
International Journal of Applied Glass Science     Hybrid Journal   (Followers: 2)
International Journal of Ceramic Engineering & Science     Open Access  
Journal of Advanced Ceramics     Open Access   (Followers: 9)
Journal of Asian Ceramic Societies     Open Access  
Journal of Ceramics     Open Access   (Followers: 3)
Journal of Non-Crystalline Solids     Hybrid Journal   (Followers: 7)
Journal of Non-Crystalline Solids : X     Open Access  
Journal of the American Ceramic Society     Hybrid Journal   (Followers: 24)
Journal of the Australian Ceramic Society     Hybrid Journal  
Journal of The Chinese Ceramic Society     Open Access  
Journal of the European Ceramic Society     Hybrid Journal   (Followers: 16)
Journal of the Korean Ceramic Society : 한국세라믹학회지     Hybrid Journal  
Liquid Crystals Today     Hybrid Journal   (Followers: 1)
Molecular Crystals and Liquid Crystals     Hybrid Journal   (Followers: 1)
New Journal of Glass and Ceramics     Open Access   (Followers: 6)
Old Potter's Almanack     Open Access  
Open Ceramics     Open Access  
Powder Metallurgy and Metal Ceramics     Hybrid Journal   (Followers: 7)
Progress in Crystal Growth and Characterization of Materials     Full-text available via subscription   (Followers: 8)
Transactions of the Indian Ceramic Society     Partially Free   (Followers: 1)
Similar Journals
Journal Cover
Powder Metallurgy and Metal Ceramics
Journal Prestige (SJR): 0.221
Number of Followers: 7  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1573-9066 - ISSN (Online) 1068-1302
Published by Springer-Verlag Homepage  [2469 journals]
  • New Design of Conduit Plasma Atomization for Fabricating Spherical Metal
           Powder and its Optimization Using Design of Experiments Method

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      Abstract: This research presents a new design of plasma atomization conducted using a graphite plasma conduit to assure prolonged interaction between molten metal and hot plasma jets. The conduit plasma atomization technique implies using a heat-collecting duct to minimize the transfer of heat energy from the plasma arc into the surrounding environment. The interaction between the molten metal and plasma arc jet is more extended. Therefore, the surface tension force of molten metal may be sufficient to form completely spherical particles, thereby eliminating satellites. The scanning electron microscopy (SEM) shows powder particles without satellites after conduit plasma atomization. This research has a strategic role in getting fundamental data for improving the efficiency of the conduit plasma atomization. A statistically designed experimental approach was followed to study the current and pressure parameter variations during newly designed conduit plasma atomization for determining median particle size distribution (D10, D50, and D90). Spherical Ti-based alloy metal powder without satellites was successfully fabricated by conduit plasma atomization with an electric current of 40 and 45 A and at gas pressures of 1.5 and 2.5 bar, using a constant feed of 2 mm3/sec. The results showed that optimization is the best parameter for the minimum particle size distribution in metal powders. After optimization, the minimum values resulting from particle size distribution D10, D50, and D90 are 71, 325, and 534 μm. The required value can be achieved by combining the current and pressure parameters of 45 A and 2.5 bar, accordingly. The regression equation can be used as a reference for operating conduit plasma atomization to obtain the required particle size distribution.
      PubDate: 2022-04-04
       
  • Mechanical and Corrosion Properties of ZrB2–SiC Composite Ceramics
           with Oxide Additions

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      Abstract: Hot pressing was used to produce compact ceramic samples with the following composition (wt.%): 60 ZrB2 + 20 SiC + 20 (Al2O3 + 32 t-ZrO2). The tetragonal modification of zirconium oxide in the eutectic was stabilized by yttrium oxide. The porosity of the samples was 3–5%. The mechanical properties of the ceramics (hardness HV, fracture toughness KIc, tensile strength δf, compressive strength Y, grain-boundary strength S, and bending strength σ) were studied. Analysis of the microstructure and elemental composition of the phases revealed that a defect-free structure developed in the ZrB2-based composite through strong Van Der Waals adhesive interaction at the SiC–Al2O3 interface, which increased the fracture toughness to 9.4 MPa ∙ m1/2. In turn, this increased the grain strength from 0.64 GPa for the basic composite to 3.46 GPa for the ZrB2–SiC composite with an oxide addition. An addition of Al2O3 + 32 wt.% t-ZrO2 was introduced in sufficient quantities not only to reduce the fracture stress but also to promote plastic deformation of the material for high-temperature bending strength. Study of the oxidation process showed that the weight increment of the 60 wt.% ZrB2 + 20 wt.% SiC + 20 wt.% (Al2O3 + 32 wt.% t-ZrO2) sample at 1600°C for a holding time of 1 h was stabilized by dense oxide scale formed on the material, while the weight increment of the ZrB2 + 20 wt.% SiC sample and, consequently, the scale thickness increased monotonically. The scale that formed on the ZrB2 + 20 wt.% SiC samples with an addition of Al2O3 + 32 wt.% t-ZrO2 consisted of an upper Al2SiO5-based layer 50 μm thick with ZrO2 inclusions and a lower ZrO2-based layer up to 80 μm thick with Al2SiO5 inclusions. The eutectic Al2O3 + 32 wt.% t-ZrO2 oxide addition to the basic ZrB2–SiC system had higher oxidation resistance and thus prevented the diffusion of oxygen into the material.
      PubDate: 2022-04-02
       
  • Synthesis and Thermal Conductivity of Ytterbium Silicate Doped with Sm and
           Gd for Environmental Barrier Coatings Application

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      Abstract: SiC/SiC ceramic matrix composite parts have begun to be used in the hot section of gas turbine engines. It is essential to prevent atmospheric corrosion in these parts. Therefore, the development of coating materials with superior properties is of particular scientific interest. The thermal conductivity of coating ceramics is also essential for protecting parts in adverse high-temperature service conditions. In this study, ytterbium silicate-based (YbSi) ceramics used as the top layer in environmental barrier coating were produced by traditional powder metallurgy methods. In addition, they were doped with the rare earth elements Sm and Gd to improve some of their properties. The ceramic samples were structurally characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal conductivity of rare earth elements–silicate samples was measured by the laser flash method. The characterization of samples allowed determining two phases in the rare earth elements–silicate pellets: mono- and disilicate. As a result of Gd doping, the percentage of the disilicate phase increased in the structure. Doping with Sm reduced the amount of this phase. The thermal diffusivity and heat capacity of YbSi ceramic were decreased by doping with Sm and Gd rare earth elements. Consequently, thermal conductivity was significantly reduced by doping Gd and Sm to YbSi ceramics. The thermal conductivity of undoped YbSi ceramics was calculated as 1.98 W(m ⋅ K)–1. However, the thermal conductivity values of YbSi ceramics doped with Gd and Sm amounted to 1.38 and 1.01 W(m ⋅ K)–1, respectively. As a result of Sm doping, the thermal conductivity of YbSi ceramic was reduced by 50%. Thus, RE-doped YbSi ceramics can be a promising candidate for environmental barrier coating applications.
      PubDate: 2022-04-02
       
  • Influence of Heat Treatment on the Mechanical Characteristics of Diamond
           Powders

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      Abstract: Improvement in the efficiency of diamond tools is inextricably linked with the use of high-strength heat-resistant diamond grains for tooling. Hence, study of the effect exerted by heat treatment on changes in the mechanical characteristics of diamonds produced in various growth systems is a relevant task. The effect of heat treatment (in an inert atmosphere) of diamond powders produced in growth systems using ferroalloys to dissolve carbon and promote the conversion of graphite into diamond on the mechanical characteristics of diamonds and elemental composition of inclusions formed on the crystal surfaces during heat treatment is examined. Following heat treatment in the range 700–1100°C, inclusions are observed on the crystal surfaces in diamonds produced in the Fe–Co–C and Fe–Ni–C growth systems. In our opinion, the effect results from ejection of the liquid metal phase to the surface by capillary forces. In crystals with a higher content of inclusions, the phenomenon of capillary ejection is manifested at lower temperatures than the melting of carbon solvent alloys in the diamond growth process. This is confirmed by a sharp change in the specific magnetic susceptibility shown by the samples with a high content of intracrystalline inclusions in the temperature range 400–800°C. For diamonds with a high content of intracrystalline inclusions, with increase in the heat treatment temperature in the range 700–1100°C, the precipitation of the solvent alloy on the surface of diamond crystals leads to crack generation and decreases the strength of diamond crystals. For diamond samples with a low content of inclusions, when the heat treatment temperature increases to 800°C, the specific magnetic susceptibility and strength hardly change (taking into account the relative error of the data obtained).
      PubDate: 2022-04-02
       
  • Changes in the Properties of Ultrafine Al2O3–ZrO2–Y2O3–CeO2 Powders
           After Heat Treatment in the Range 400–1450°C

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      Abstract: Ultrafine 90AZK, 80AZK, 70AZK, and 58.5AZK powders in the Al2O3–ZrO2–Y2O3–CeO2 system were produced for the first time by a combined method involving hydrothermal synthesis followed by mechanical mixing with α-Al2O3 (HTSM). The properties of the powders heat treated in the range 400-1450°C were examined by differential thermal analysis, X-ray diffraction, electron microscopy, and nitrogen thermal adsorption–desorption (BET). The sizes of primary particles were calculated with the Scherrer equation. The AMIC (Automatic Microstructure Analyzer) software was applied to process the powder morphology analysis results. The F-ZrO2 → T-ZrO2 phase transformation was found to proceed completely when the powders were mechanically mixed in the HTSM process. The M-ZrO2 phase was identified as traces in the ultrafine 90AZK and 80AZK powders after mechanical mixing, was not found in the 70AZK powder, and emerged as traces in the 58.5AZK powder above 1150°C. Heat treatment was shown to induce a topochemical memory effect in the ceramics: the morphology and shape factor of the ultrafine powders following heat treatment at 400–1450°C varied topologically continuously. The dependence of primary particle sizes and specific surface area of the powders on the heat treatment temperature indicated that they had high sintering activity. The powders are needed to produce highly efficient ZTA composites in the Al2O3–ZrO2–Y2O3–CeO2 system, consisting of fine particles of the viscous zirconia-based solid solution, codoped with ceria and yttria, distributed in a rigid alumina matrix.
      PubDate: 2022-04-02
       
  • Effects of Spark Plasma Sintering Parameters on Microstructure and
           Properties of Al–50 wt.% Si Alloys

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      Abstract: Al–Si alloy powder was prepared by the gas atomization method, followed by the production of the Al–50 wt.% Si alloy used in electronic packaging by spark plasma sintering (SPS) under different parameters. Afterward, the alloy’s microstructure, phase composition, mechanical properties, coefficient of thermal expansion (CTE), and thermal conductivity (TC) were analyzed. The results show that the uniform Al–50 wt.% Si alloy with a primary silicon size of less than 10 μm can be obtained by gas atomization and SPS techniques. Compared with the powder, the XRD alloy patterns remain the same after SPS, with α-Al and β-Si diffraction peaks and no other phase formation. The change of SPS temperature and time may affect the accumulation of primary silicon in the alloy and thus influence the alloy’s mechanical and thermal properties. The tensile strength of the alloy gradually increased to 220 MPa (550°C, 15 min) with the rise of SPS temperature. In contrast, the coefficient of thermal expansion (and thermal conductivity of the alloy decreased with a further increase in the temperature. Optimal values of coefficient of thermal expansion (10.6 × × 10–6 K–1), thermal conductivity (128 W · m–1 · K–1), and tensile strength (210 MPa) were obtained at 500°C and 15 min of the SPS process. A relationship between the primary silicon morphology and material properties was established to understand the alloy’s thermal behavior changes. This change is mainly caused by the CTE and TC values difference between the Al matrix and Si-phase. The initially uniformly distributed primary silicon accumulates and modifies the properties of the alloy. The coefficient of thermal expansion and thermal conductivity variation were discussed in terms of changes in alloy particle morphology, and the theoretical model of CTE was then analyzed.
      PubDate: 2022-04-01
       
  • Well-Dispersion of Nanoscale WC Particles in WC–Cu Composites Prepared
           by Molecular Level Mixing and Spark Plasma Sintering

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      Abstract: In the present work, Cu–3.0 vol.% WC powders and WC reinforced copper matrix composites were successfully fabricated by combining molecular level mixing (MLM) and spark plasma sintering (SPS) techniques. The microstructure and phase analysis of WC/Cu composite powders prepared by MLM showed that these powders existed in the form of a core-shell structure. Specifically, copper was distributed outside the WC particles as the shell, and WC was located in the center as the core, which initiated the pre-dispersion of WC particles in copper. Furthermore, the thickness of the copper layer was about 10 nm. According to SEM and TEM analysis, the outline of WC/Cu composite particles was closer to a spherical shape. The microstructure characterization of WC–Cu composites showed a good dispersion of the nanoscale WC particles in the composites. Compared to untreated WC–Cu composites, the tensile strength and softening temperature of MLM composite increased significantly from 203 to 223 MPa, and 700 to 800°C, respectively. The density and electrical conductivity of MLM WC/Cu composites increased from 94.18 and 83.2% IACS to 96.72 and 87.5% IACS, respectively. The rise from 17.1 to 20.2% was observed in elongation, as well as tensile strength and toughness by 9.6 and 18.1%, respectively. The above strengthening phenomena were caused by the well-dispersion of WC and Cu phases in the composites. Finally, the wear resistance of composites was tested and contrasted. The results demonstrated that WC particles with uniform distribution decreased composite’s COF. The specific COF value of MLM composites was 0.34 and 0.43 for composites without MLM. These results show that uniformly WC particles could effectively enhance the wear resistance of composites. The three-dimensional profile analysis of wear marks also demonstrated that the wear rate of composites was reduced with uniformly distributed WC additives.
      PubDate: 2022-04-01
       
  • Interaction of Titanium Diboride with Nickel and Ni–20% Cr Alloy
           (Nichrome)

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      Abstract: The interaction in the Ni–Ti–B and Ni–Ti–B–Cr systems along the Ni–TiB2 and (Ni–20% Cr)–TiB2 sections was studied. Solid-phase interaction was not found to occur for Ni–TiB2 up to 1200°C. In the case of (Ni–20% Cr)–TiB2, a new phase was formed, Cr2B, with a thickness of ~5 μm at a temperature of 1200°C. The contact melting began above 1200°C in the Ni–TiB2 system and above 1180°C in the (Ni–20% Cr)–TiB2 system. In the (Ni–20% Cr)–TiB2 system, the emerged liquid wetted titanium diboride with an angle of 50°; when temperature increased to 1450°C, the liquid spread completely on the TiB2 surface. In the contact melting process, several areas formed: titanium diboride area, Ni3B and TiB area, Ni and TiB area, and pure nickel. The systems were eutectic and their quasibinary phase diagrams had a eutectic at ~9% TiB2 with a melting point of ~1200°C at the Ni–TiB2 section and a melting point of ~1180°C at the (Ni–20% Cr)–TiB2 section. The alloys in the hypoeutectic part of the phase diagram consisted of the Ni, Ni3B, and TiB phases and additionally of the Cr2B phase in the (Ni–20% Cr)–TiB2 system. In the hypereutectic part of the phase diagram, the metal component disappeared and unreacted TiB2 additionally appeared in the (Ni–20% Cr)–TiB2 system. Zero solid-phase interaction and contact melting observed at temperatures of 1200 and 1180°C, which were significantly lower than the melting points of the interacting components (Ni, Ni–Cr), promoted favorable conditions for the use of nickel as a metal component in wear-resistant composites produced from granular titanium diboride, capable of operating under dynamic and shock loads at elevated temperatures (~900°C) and in corrosive environments.
      PubDate: 2022-04-01
       
  • Evaluation of the Explosion Hazard of Powders by the Maximum Explosion
           Pressure and Maximum Rate of Explosion Pressure Rise I. Explosion
           Expansion in Gas Suspensions

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      Abstract: The features of powder explosion propagation in closed equipment and equipment with explosion venting are considered. A near-proportional dependence of the maximum explosion pressure on the initial pressure values in closed vessels is observed. The increase in ignition delay from lowest value 0.3 sec to about 1 sec results in a substantial decrease in the maximum rate of pressure rise, whereas the maximum explosion pressure is comparatively independent of the ignition delay. Mechanisms of transition from laminar combustion to turbulent combustion and subsequent acceleration of powder flames up to the detonation speed are addressed. When the detonation speed is reached, the flame front propagates along the exhaust duct connected with the equipment and then an explosive wave of combustible dust sediments rises over the entire duct length.
      PubDate: 2022-04-01
       
  • Interaction of Components in Glass-Forming Melts of Iron and Nickel with
           Titanium, Zirconium, and Hafnium I. Mixing Enthalpies of Liquid Alloys

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      Abstract: The mixing enthalpies of glass-forming Fe–Ni–Ti, Fe–Ni–Zr, and Fe–Ni–Hf liquid alloys were investigated at 1873 K by high-temperature calorimetry. The thermodynamic properties of melts in the Fe–Ni–Hf system were studied for the first time. Along the studied sections (xFe/xNi = 0.50/0.50 at xTi = 0–0.15, xFe/xNi = 0.50/0.50 at xZr = 0–0.45, xFe/xNi = 0.75/0.25 at xHf = 0–0.18, xFe/xNi = 0.50/0.50 at xHf = 0–0.45, and xFe/xNi = 0.25/0.75 at xHf = 0–0.46), the partial mixing enthalpies of IVB metals and the integral mixing enthalpy showed negative values. New experimental data on the integral mixing enthalpy of the liquid alloys were combined with the literature data, and the ∆mH isotherms of the ternary Fe–Ni–Ti, Fe–Ni–Zr, and Fe–Ni–Hf liquid alloys at 1873 K were plotted using the Redlich–Kister–Muggianu equation. The ∆mH function was negative in each of the studied systems, being indicative of strong interparticle interaction of the components in the glass-forming liquid alloys. The composition dependence of the integral mixing enthalpy of the liquid alloys and its change in the series of the systems can be qualitatively interpreted in terms of the electronegativity of the chemical elements in the liquid alloys.
      PubDate: 2022-04-01
       
  • 3d Printing of Porous Glass Products Using the Robocasting Technique

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      Abstract: 3D printing of porous SiO2–Al2O3–Fe2O3–MgO–CaO–Na2O glass products with use of the robocasting technique was comprehensively studied. Features in the preparation of glass-based pastes with gelatin or agar for 3D printing were established and recommendations on the printing of porous glass products employing a ZMORPH 3D printer equipped with a thick paste extruder were developed. The method of preparing glass/gelatin and glass/agar pastes for 3D printing was tested experimentally. Mixtures with different contents of gelatin or agar, glass, and water were analyzed, and conditions for their storage from the time the paste components were mixed to the time they were loaded into the 3D printer were determined. The optimal 3D printing parameters were chosen with the Voxelizer software for the ZMORPH 3D printer with a thick paste extruder. A modification to the ceramic module for printing with pastes was proposed. The heat treatment process at 160 and 260°C and sintering at 600–650°C for the printed samples were studied. The temperature threshold at which a powdered glass material sintered without transiting to the molten state was found experimentally by choosing optimal temperatures and holding times. Heat treatment resulted in glass samples of complex shape. The samples reached 49% porosity. The mechanical properties and microstructure of the sintered porous glass samples were analyzed. The wear resistance and fracture of the samples were examined by repeated scratching with a conical diamond indenter.
      PubDate: 2022-04-01
       
  • Tribological Properties of ZrN–Si3N4–TiN Composites Consolidated by
           Spark Plasma Sintering

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      Abstract: The production of ZrN–Si3N4 and ZrN–Si3N4–TiN composites by spark plasma sintering and the mechanical and tribological properties of the consolidated materials were studied. The densification of the ZrN–Si3N4–TiN composites was found to proceed more intensively in the range 1100–1300°C, and nanocrystalline titanium nitride was the main factor that promoted the densification of these composites. Ceramic 57 wt.% ZrN–43 wt.% Si3N4 and 84 wt.% ZrN–16 wt.% Si3N4 samples with a relative density of 0.95 and 0.93 and (84 wt.% ZrN–16 wt.% Si3N4)–15 wt.% TiN and (57 wt.% ZrN– 43 wt.% Si3N4)–30 wt.% TiN composites with a relative density of ~0.98 were produced. Microstructural studies showed that components of the consolidated ZrN–Si3N4 composites were uniformly distributed over the material with an average grain size of 200–300 nm. The ZrN–Si3N4– TiN composites had a finer structure, TiN grains being smaller than 100 nm. The mechanical properties of the titanium nitride composites were higher than those of the ZrN–Si3N4 materials. Thus, the Vickers hardness and indentation-determined fracture toughness of the composites containing 15 and 30 wt.% TiN were 18.7 ± 1.1 GPa and 5.2 MPa ∙ m1/2 and 19.1 ± 1.9 GPa and 5.8 MPa ∙ m1/2, respectively. The hardness of the ZrN–Si3N4 composites was ~17 GPa. The tribological properties of the composites were tested with the VK6 hardmetal and silicon nitride. The wear resistance of the ceramic samples directly depended on the contents of zirconium nitride and counterface, i.e., on their physicochemical interaction. When the ZrN content increased to 84%, the tribological properties of the composites improved substantially through the lubricating capability of zirconium nitride. The (84 wt.% ZrN–16 wt.% Si3N4)–15 wt.% TiN composite showed the best tribological properties and can be recommended for use in friction units under dynamic loads.
      PubDate: 2022-04-01
       
  • Information on the Annual Report of the Ukrainian Commission of Phase
           Diagrams and Thermodynamics (2021)

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      Abstract: The main tasks of the international scientific organization Alloy Phase Diagram International Commission (APDIC), which unites 18 member organizations involving 26 countries, are the exchange of information and coordination of the activities of the international scientific community, mainly in the field of phase diagrams and thermodynamics. The Ukrainian Phase Diagrams and Thermodynamics Commission has been a member of APDIC since 1994. The annual report of the Ukrainian Commission on the results of the activities of Ukrainian scientists in this field in 2020 was presented at the APDIC meeting on June 18, 2021, which was held online due to the coronavirus pandemic. This information is presented in a table, collecting data on the studied systems and obtained result and containing a list of references to published papers. Scientists from the Frantsevich Institute for Problems of Materials Science (National Academy of Sciences of Ukraine, Kyiv), Taras Shevchenko National University of Kyiv (Ministry of Education and Science of Ukraine, Kyiv), and Donbas State Engineering Academy (Ministry of Education and Science of Ukraine, Kramatorsk) provided relevant information to the Ukrainian Commission.
      PubDate: 2022-04-01
       
  • Highly Active Granular Nickel Powders for Multi-Batch Production of Spongy
           Oxide Cathodes

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      Abstract: A process was developed for the production of agglomerated carbonyl nickel powders with spherical particles ranging from 45 to 71 μm. The powders are intended to make spongy oxide/nickel cathodes. The idea relied on the separation of integral and local compaction effects in the sintering of agglomerated powders. The morphology and particle size of the powders were examined by scanning electron microscopy using a Superprobe-733 analyzer. The nickel powders were chemically tested to determine their carbon content with automatic coulometric titration by pH values employing an AN-7529U rapid analyzer. The agglomerated carbonyl nickel powders with spherical 45–71 μm particles were produced from PNK-1L5 carbonyl nickel powders with average particle sizes of 4 μm by annealing without mechanical grinding. The optimum process of producing nickel powders with 45–71 μm particles involves stage-by-stage annealing of agglomerated particles at 400, 500, and 600°C for 0.5 h with intermediate sifting through sieves 071 and 045. Testing of the spongy oxide/nickel cathodes produced in compliance with the agglomeration process for the fine PNK-1L5 nickel powders showed that they could be used to replace the PNK-2K10 nickel powders.
      PubDate: 2022-01-03
      DOI: 10.1007/s11106-021-00252-y
       
  • Corrosion-Resistant Composite Coatings Reinforced by Decagonal
           Quasicrystals

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      Abstract: The structure and corrosion properties of quasicrystalline Al65Co20Cu15 and Al72Co18Ni10 reinforcement alloys and associated composite coatings produced by pressureless infiltration were studied. Copper-based L62 and BrOTs 10-2 alloys and aluminum-based AMg30 alloy were used as metallic matrices for the composite coatings. The structural and phase composition of the reinforcement alloys and coatings was determined by metallography, scanning electron microscopy, energy-dispersive X-ray spectrometry, and X-ray diffraction. The corrosion properties were studied in aqueous solutions of HCl, H2SO4, HNO3, and H3PO4 acids (pH = 1.0) for 1 to 4 h at room temperature. A quasicrystalline decagonal D phase was found to coexist with crystalline Al4(Co, Cu)3 and Al3(Cu, Co)2 phases in the Al65Co20Cu15 reinforcement alloy and Al9(Co, Ni)2 and Al(Co, Ni)2 phases in the Al72Co18Ni10 alloy. Corrosion tests in acid solutions revealed that the Al65Co20Cu15 reinforcement alloy had higher corrosion resistance in sulfuric and nitric acid solutions, while the Al72Co18Ni10 reinforcement alloy in hydrochloric and phosphoric acid solutions. In infiltration of the Al65Co20Cu15 and Al72Co18Ni10 reinforcement alloys, the molten copper-based L62 and BrOTs 10-2 matrices penetrated into the reinforcement along boundaries of the quasicrystalline D phase through the preferential dissolution of crystalline phases of the reinforcement alloys. Unlike the copper-based alloys, the aluminum-based AMg30 matrix did not penetrate inside the reinforcement alloys, dissolving predominantly the crystalline phases located in the surface layers. The highest corrosion resistance in the acidic environments was shown by the composite coatings with the BrOTs 10-2 matrix. The coatings with the AMg30 matrix had the lowest corrosion resistance because of the Al3Mg2 phase that emerged at interfaces between the reinforcement alloy and solidified matrix.
      PubDate: 2022-01-03
      DOI: 10.1007/s11106-021-00258-6
       
  • Effect of Heat Treatment in the Temperature Range 400−1300°C on the
           Properties of Nanocrystalline ZrO2−Y2O3−CeO2 Powders

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      Abstract: The properties of nanocrystalline powders of compositions (mol.%) 97 ZrO2–Y2O3, 95 ZrO2–3 Y2O3–2 CeO2, 92.5 ZrO2–2.5 Y2O3–5 CeO2, 90 ZrO2–2 Y2O3–8 CeO2, and 88 ZrO2–12 CeO2 were studied. The powders were produced by hydrothermal synthesis in an alkaline environment from a coprecipitated hydroxide mixture with a residual moisture of 15–20%. The powder properties were determined by X-ray diffraction (XRD), electron microscopy, BET, and petrography. Metastable F-ZrO2 was found to form in the hydrothermally synthesized powders. According to XRD, the F-ZrO2 → T-ZrO2 phase transformation began at 700°C and finished at 850–1000°C. The crystal optical characteristics of the powders indicate that the F-ZrO2 → T-ZrO2 phase transformation started at 400°C. The variations in F-ZrO2 and T-ZrO2 unit cell volumes are associated with lattice distortions under the action of different mechanisms in costabilization of the zirconia-based solid solution and with the ratio of Y2O3 and CeO2 in the solid solution. The tetragonality of the powders increases in the ZrO2 costabilization. The transformation strengthening mechanism for ceramics based on ZrO2 (Y2O3, CeO2) solid solutions becomes more effective with the formation of T-ZrO2, whose capability to the T-ZrO2 → M-ZrO2 phase transformation increases. The morphology of the powders varies topologically continuously, and the sizes of their primary particles hardly increase up to 1150°C. The variation in the specific surface area (from 153 to 2 m2/g) of the powders is determined by the F-ZrO2 → T-ZrO2 phase transformation and their sintering activity above 1000°C.
      PubDate: 2022-01-03
      DOI: 10.1007/s11106-021-00251-z
       
  • Electron-Beam Physical Vapor Deposition of Iron Nanoparticles and their
           Thermal Stability in the Fe–O System

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      Abstract: Chemically pure (ligand-free) 5–70 nm iron nanoparticles were synthesized by electron-beam physical vapor deposition (EB-PVD) in a porous NaCl matrix. The influence of chemical composition, substrate temperature, and isothermal treatment on the dimensional, structural, and phase composition of nanoparticles in the Fe–O system was studied. For this purpose, independent molecular fluxes of Fe and NaCl were applied to a fixed substrate by electron-beam physical vapor deposition (EB-PVD) at substrate temperatures of 45–400°C to produce 3–30 wt.% Fe–NaCl condensates. With increasing iron content, substrate temperature, and heat treatment temperature, the average size of particles in the Fe–O system became greater. To study the oxidation kinetics of iron nanoparticles, the condensates produced at a substrate temperature of 45°C were isothermally treated in air at 200–650°C. The condensates were examined by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, and aqueous solutions of the condensates by dynamic light scattering. Being of small size and thus having high adsorption capacity for air and moisture oxygen, iron exothermally oxidized in the condensate when the vacuum chamber was opened and the condensate was separated from the substrate. At different substrate temperatures and after heat treatment, the nanoparticles may contain pure iron and iron oxides Fe3O4 and Fe2O3. In the studied condensates, the α-Fe phase is present only when the iron content is more than 20 at.%. This is explained by the fact that not all nanoparticles (crystallites) have time to oxidize to the Fe3O4 phase with increase in their sizes. In addition, Fe3O4 nanoparticles additionally adsorb oxygen. The ratio between the atomic percentage of oxygen and iron depends on the amount of iron, decreases with increasing iron content of the condensate, and even exceeds the value for the stoichiometric composition of Fe2O3, being equal to 1.5. The study shows that the EB-PVD method is universal in the use of inorganic materials for the synthesis and retention of pure nanoparticles of metals and their oxides.
      PubDate: 2022-01-03
      DOI: 10.1007/s11106-021-00256-8
       
  • Interaction of Titanium Diboride with Iron and AISI 321H Stainless Steel

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      Abstract: The interaction of titanium diboride with iron and Kh18N10T iron alloy (equivalent to AISI 321H) in the temperature range 1200–1850°C was studied. No solid-state interaction was found at the contact interface. In the high-temperature range, the interaction proceeds according to the contact melting mechanism, which is characteristic of eutectic systems. Contact melting in the iron–titanium diboride system occurs at ~1400°C and in the 321H–diboride system at ~1340°C. The resultant liquid phase wets the diboride surface with a contact angle of ~40°. When temperature increases to 1450°C, the contact angle does not change and the droplet does not spread over the surface. Study of the alloys showed that the eutectic was found at point 9 ± 2 wt.% TiB2 for the Fe–TiB2 system and 6–7 wt.% TiB2 for the 321H–TiB2 system. The phase composition of the eutectic depends on the titanium diboride amount in the alloy. In the Fe–TiB2 system, the crystallized alloy retains the original phase composition (Fe, TiB2) but has a hypoeutectic, hypereutectic, or eutectic structure. At high TiB2 content, titanium diboride that did not participate in the interaction was identified in the alloy. In the 321H–TiB2 alloys, in addition to the main components (stainless steel and titanium diboride), small amounts of TiC and σ-phase (Cr0.56Fe0.46), resulting from stainless steel decomposition, were found. The experimental data indicate that iron in contact with titanium diboride can operate up to 1400°C and 321H iron alloy up to 1300°C. Iron and its alloys are promising matrix materials for composites in which pure iron or iron alloys are a metallic matrix and titanium diboride is a hard and wear-resistant component.
      PubDate: 2021-12-02
      DOI: 10.1007/s11106-021-00257-7
       
  • Powder Compaction Dies and Compressibility of Various Materials

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      Abstract: Powder compaction is the most crucial process in powder metallurgy since almost all the desired properties of a material, such as a shape, size, density, porosity, hardness, and other mechanical properties, can be controlled during this process. The powder compaction can be performed differently depending on the type of die (single-piece or split), the punch movement, and processing parameters. According to the punch movement, there are two types of compaction, uniaxial or multiaxial. Uniaxial compaction can also be divided into single-action and double-action subtypes. Thus, single-action uniaxial compaction implies that only the upper punch can move, and the lower one remains fixed. When both the upper and lower punches are moving, the process is called a double-action uniaxial compaction. If, at the same time, the powder is compacted from more than one side, then compaction is said to be multiaxial. During isostatic pressing, pressure is exerted on powder in all directions, implying a multiaxial compression. Properties of a powder metallurgy green compact depend on the type (uniaxial or isostatic) and pressure of powder compaction, as well as the type of matrix material and reinforcing agent (metallic, carbonaceous, or ceramic). This work involves a comparative study of different types of powder compaction dies. Also, the compressibility of different matrix materials (i.e., Al6061, Mg, and Cu) and various reinforcing agents (metallic, carbonaceous, and ceramic) was examined experimentally. The analysis of different powder compaction dies revealed that the isostatic pressing ensures uniform densification but is more costly. The compressibility of Al6061 was the greatest, and the compressibility of Cu 10% B4C was the lowest. The addition of metallic and carbonaceous reinforcements enhanced compressibility, while ceramic reinforcing agents contributed to its reduction.
      PubDate: 2021-11-01
      DOI: 10.1007/s11106-021-00253-x
       
  • Wetting and Contact Interaction of Nickel Alloy with ZrB2 and (Ti, Cr)B2
           Ceramic Materials

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      Abstract: The ZrB2–MoSi2–AlN, ZrB2–SiC–AlN, and (Ti, Cr)B2–AlN ceramic composites were wetted with a nickel-based alloy in the Ni–Cr–W–Mo system. The alloy was found to wet the ceramic composites well to form contact angles θ = 0–12° for 3–7 min on their surface. The wetting process was less influenced by the composition of the main phase (ZrB2 and (Ti, Cr)B2) and greater by the content of SiC and AlN dielectric additions, impairing the wetting of the composites. The interaction areas were studied on cross-sections of the wetted samples. Three characteristic areas were found: refractory substrate area, transition area, and metal droplet area. The composition and microstructure of the starting ceramic material were retained by the refractory substrate area. The pores and cracks were filled with the molten alloy in the transition area at a depth up to 150 μm. There was no active chemical interaction between the metal alloy and ceramic composites, though there was insignificant diffusion (up to 3%) of some elements between the refractory substrate and the metal alloy in a thin contact area to form limited solid solutions. This was mostly observed in the wetting of materials containing SiC and MoSi2 and was manifested through the diffusion of silicon into the metal alloy. In the wetting of (Ti, Cr)B2-based materials, 1–2% of the ceramic substrate was insignificantly depleted of chromium in a narrow (3–7 μm) contact area. Despite this, the composition of the refractory substrate and the metal alloy in the interaction area was close to the starting one. In the droplet area, besides the main phase based on the NiCr solid solution, whose composition was close to that of the starting material, single inclusions of the chromium-based phase with high tungsten and molybdenum contents were found. Good wetting of the ceramic composites with the metal alloy and zero active chemical interaction between the components allow them to be jointly used for spraying coatings and making metal–ceramic composites.
      PubDate: 2021-11-01
      DOI: 10.1007/s11106-021-00260-y
       
 
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