 Subjects -> METALLURGY (Total: 59 journals)
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- Synthesis of ascorbic acid enhanced TiO2 photocatalyst: its
characterization and catalytic activity in CO2 photoreduction
Authors: Mohd Farid Bin Mohd Na'aim, Raihan Mahirah Binti Ramli, Noor Asmawati Binti Mohd Zabidi
Pages: 1 - 16
Abstract: To date, the development of solar environmental remediation has shifted more emphasis on the green and simple synthesis of catalyst for CO2 photocatalysis process. Herein, TiO2 photocatalyst was successfully synthesized via hydrothermal method. The effects of the different molar ratio of ascorbic acid C6H8O6, (AA) added during the preparation of TiO2 nanoparticles were comprehensively studied. The characterization of TiO2 nanocrystals was performed via XRD, XPS, DRUV-vis, and FTIR. The results show the AA loading into TiO2 nanoparticles significantly intensified the XRD spectra of anatase structure. In fact, this feature had signified a reactivity of the photocatalyst in the visible region. In an instance, BET surface area was also enhanced with the highest recorded value of 135.14 m2/g for 0.8AA. Meanwhile, the CO2 photoreduction over synthesized TiO2 had produced the highest amount of HCOOH at 39.3 μmol/g cat for 0.8AA within 6 hours of reaction time. Furthermore, the DRUV-vis analysis had illustrated better light absorption ability of 0.8AA. This profound finding is attributed to the correlation between large surface area, pure anatase phase, and high adsorbed water molecules. Therefore, this study had significantly demonstrated the potential of modified TiO2 with AA in CO2 photocatalysis area while simultaneously presents a green and simple method for TiO2 synthesis.
PubDate: 2018-04-02
DOI: 10.30544/327
Issue No: Vol. 24, No. 1 (2018)
- A study on direct alloying with molybdenum oxides by feed wire method
Authors: Jingjing Zou, Hangyu Zhu, Jian Sun, Jigang Liu, Jixuan Zhao
Pages: 17 - 25
Abstract: Direct alloying with molybdenum oxides has been regarded in years; the main addition methods are adding to the bottom of electric arc furnace (EAF) with scrap, adding to the ladle during the converter tapping and mixing molybdenum oxide, lime and reductant to prepare pellet added to basic oxygen furnace (BOF). In this paper, a new method for direct alloying with molybdenum trioxide is proposed, adding molybdenum trioxide molten steel by feeding wire method in ladle furnace (LF) refining process. The feasibility of molybdenum oxide reduction, the influence rules of bottom-blown on liquid steel fluidity and the yield of molybdenum by feeding wire method were analyzed. Results show that molybdenum oxide can be reduced by [Al], [Si], [C], and even [Fe] in molten steel. Bottom blowing position has a significant influence on the flow of molten steel when the permeable brick is located in 1/2 radius. The yields of Mo are higher than 97% for the experiments with feed wire method, the implementation of direct alloying with molybdenum trioxide by feed wire method works even better than that uses of ferromolybdenum in the traditional process.
PubDate: 2018-04-02
DOI: 10.30544/346
Issue No: Vol. 24, No. 1 (2018)
- Microstructural investigations and mechanical properties of pure lead-free
(Sn–3.0Ag–0.5Cu and Sn–4.0Ag–0.5Cu) solder alloy
Authors: Manoj Kumar Pal, Gréta Gergely, Dániel Koncz Horváth, Zoltán Gácsi
Pages: 27 - 36
Abstract: The Lead-free solders (SAC) with low Ag content have been identified as crucial solder to replace the traditional Sn–Pb solder. The main discussion was presented in two major area of microstructural investigation and mechanical properties of SAC305 and SAC405. Composition and microstructure of SAC solder alloys were investigated by an optical microscope and SEM (Scanning Electron Microscopy). Mechanical properties such as tensile tests and hardness test of the lead-free solder alloys have been tested in this research. Different Ag content and constant Cu content of lead-free solder has been considered in this investigation and compare the mechanical properties of SAC305 and SAC405 solders. From this investigation, tensile strength and hardness have been increased with increased of Ag content.
PubDate: 2018-04-02
DOI: 10.30544/344
Issue No: Vol. 24, No. 1 (2018)
- Effect of cooling rates on the weld heat affected zone coarse grain
microstructure
Authors: Roman Celin, Jaka Burja
Pages: 37 - 44
Abstract: The effect of a cooling rate on the S690Q quenched and tempered steel welded joint coarse grain heat affected zone microstructure was investigated using a dilatometer with controlled heating and cooling fixture. Steel samples were heated to a peak temperature of 1350 °C and cooled at the different cooling time Dt8/5. A dilatometric analysis and hardness measurements of the simulated thermal cycle coarse grain samples were done. Transformation start and finish temperature were determined using dilatation vs. temperature data analysis. The microstructure of the sample with a cooling time 5 s consists of martensite, whereas at cooling time 80 s a bainitic microstructure was observed. The investigated steel cooling cycle using simulation approach makes possible to determine the range of an optimum CG HAZ cooling time for the welding.
PubDate: 2018-04-02
DOI: 10.30544/342
Issue No: Vol. 24, No. 1 (2018)
- A preliminary investigation on microstructure and mechanical properties of
dissimilar Al to Cu friction stir welds prepared using silver interlayer
Authors: Shailesh N. Pandya, Jyoti Menghani
Pages: 45 - 57
Abstract: Due to its solid-state nature, friction stir welding (FSW) process can be considered a better alternative for dissimilar welding metals. However, like fusion welding techniques, in friction stir welding growth of thick layers of brittle intermetallics - Cu9Al4 and CuAl2 is a significant issue. One solution to this problem is the use of the suitable interlayer material. Use of interlayer material modifies the joint microstructure with the replacement of thick, brittle intermetallics by more ductile intermetallics in a thin layer or particle form. The present study is a preliminary investigation about joining of AA6082-O to pure copper joints with and without silver (Ag) wire interlayer. Friction stir welded joints were characterized regarding optical microscopy, X-Ray Diffraction (XRD) analysis, microhardness measurement, tensile testing and Scanning Electron Microscopy (SEM) based fractography. The Al-Cu weld prepared using silver interlayer was stronger than without it. The higher strength of the weld with silver interlayer is attributed to the formation of a composite type of structure with intercalation of more ductile Ag2Al intermetallics along with dispersion of Ag particles in stir zone.
PubDate: 2018-04-02
DOI: 10.30544/294
Issue No: Vol. 24, No. 1 (2018)
- Finite element analysis and modeling of temperature distribution in
turning of titanium alloys
Authors: Moola Mohan Reddy, Mohan Kumar, Kumaraesan Shanmugam
Pages: 59 - 69
Abstract: The titanium alloys (Ti-6Al-4V) have been widely used in aerospace, and medical applications and the demand is ever-growing due to its outstanding properties. In this paper, the finite element modeling on machinability of Ti-6Al-4V using cubic boron nitride and polycrystalline diamond tool in dry turning environment was investigated. This research was carried out to generate mathematical models at 95% confidence level for cutting force and temperature distribution regarding cutting speed, feed rate and depth of cut. The Box-Behnken design of experiment was used as Response Surface Model to generate combinations of cutting variables for modeling. Then, finite element simulation was performed using AdvantEdge®. The influence of each cutting parameters on the cutting responses was investigated using Analysis of Variance. The analysis shows that depth of cut is the most influential parameter on resultant cutting force whereas feed rate is the most influential parameter on cutting temperature. Also, the effect of the cutting-edge radius was investigated for both tools. This research would help to maximize the tool life and to improve surface finish.
PubDate: 2018-04-02
DOI: 10.30544/323
Issue No: Vol. 24, No. 1 (2018)
- Development of ferro-alloy hardfacing for high abrasion and low impact
wear applications
Authors: Chijioke Okechukwu, Olurotimi Akintunde Dahunsi, Peter Kayode Oke, Isiaka Oluwole Oladele, Mohammed Dauda
Pages: 71 - 81
Abstract: Extension of service lives of critical machine components subjected to wear is possible through application of hardfacing alloys. In this work, two hardfacing alloys were produced based on the mass ratios of 2: 1: 1 and 7: 1.5: 1.5 for Fe: Mn: Cr by sand and open permanent mold casting processes, respectively. XRD analysis of both samples showed the prominent presence of (Mn, Cr)23C6, (Fe, Mn, Cr)7C3, Cr3C2, Fe3C2 and Fe4C carbides. Hӓgg carbide was prevalent in the SEM microstructural analysis of the sand cast sample, while cementite dominated the permanent mold cast sample. The average hardness values, impact energies absorbed and wear volumes of the samples produced with their respective charge mass ratios are 567 HV, 30 J and 0.131 cm3 for 2: 1: 1 ratio and 592 HV, 29.5 J and 0.085 cm3 for the 7: 1.5: 1.5 ratio. For service life applications as jaws, rolls, mantles, and concaves in crushers, the latter was recommended for manual metal arc welding to low carbon steel substrate because of its higher hardness, lower wear volume and cheaper alloy cost.
PubDate: 2018-04-02
DOI: 10.30544/338
Issue No: Vol. 24, No. 1 (2018)
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