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Key engineering materials
Trans Tech Publications Ltd.
Key engineering materials

Trans Tech Publications Ltd.

半月刊

1013-9826

Key engineering materials/Journal Key engineering materials
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    Nickel-Hydroxyapatite as Biomaterial Catalysts for Hydrogen Production via Glycerot Steam Reforming

    Lukman HakimZahira YaakobManal IsmailWan Ramli Wan Daud...
    P.770-774页
    查看更多>>摘要：Nickel-hydroxyapatite as biomaterial catalysts exhibited high activity and selectivity in glycerol steam reforming. The catalytic steam reforming of glycerol (C_3H_8O_3) for the production of hydrogen is carried out over nickel supported on hydroxyapatite [Ca_5(PO_4)_3(OH)] catalyst at 600 ℃ with atmospheric pressure and 120 minute time reaction. The catalysts were prepared by mean of wet impregnation method and varied nickel loadings (3, 6, 12 %) on hydroxyapatite. It is found that the 3% wt% Ni/HAP show higher hydrogen production rate over the other nickel loadings on hydroxyapatite, which is correlated with Ni/HAP catalyst surface area measured by BET adsorbtion and morphology of catalysts. Glycerol steam reforming with water-to-glycerol feed ratio 8/1 much more hydrogen production (77-82%) compared feed ratio 4/1. The catalysts were characterised by BET surface area and SEM-EDX techniques.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Study Effect of Stress in the Electrical Contact Resistance of Bipolar Plate and Membrane Electrode Assembly in Proton Exchange Membrane Fuel Cell: A Review

    Miftah KurniawanWan Ramli Wan DaudEdy Herianto Majlan
    P.775-779页
    查看更多>>摘要：Stress applying in the stack of Proton Exchange Membrane Fuel Cell (PEMFC) effects the performance of PEMFC. High pressure in the Membrane Electrode Assembly (MEA) can reduce electrical contact resistance between bipolar plate and MEA. Nevertheless, too high pressure in the PEMFC can destroy MEA. Performance of PEMFC can be optimized by make proportional stress in the assembly of PEMFC. Finite element analysis (FEA) is one of method that can be used for analysis of stress in the PEMFC stack. However, setting of parameter in the analysis using FEA still became one of problem if realistic result must be desired. This paper reports setting of parameters in the stress analysis of PEMFC assembly using FEA method and study relationship of stress analysis with electrical contact resistance.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Properties of Test Coupons Fabricated by Selective Laser Melting

    A. LiuC.K. ChuaK.F. Leong
    P.780-784页
    查看更多>>摘要：Selective Laser Melting (SLM) is a popular and promising Additive Manufacturing (AM) technique as it can produce parts with complex internal features with part density close to 100%. However, unprocessed raw SLM fabricated parts have surface roughness issues and the mechanical properties of raw SLM parts without heat treatment are not ideal. The material used to address some of these issues in this research is an Aluminum alloy, AlSi_(10)Mg - a strong and light weight metal. The SLM machine engaged for the test coupons fabrication is M2 Cusing from Concept Laser, Germany, which uses a diode pumped Yb-Fibre laser (Ytterbium-doped fibre lasers) with an effective output power of 200W. It is found that SLM fabricated parts with and without sandblasting shows up to 80% difference in surface roughness values. Also, the tensile test experiments of raw untreated SLM parts carried out at room temperature and at high temperature (200℃) show superior result compared with heat treated casted parts. Other properties such as hardness and density (porosity) are found to be better than heat treated cast parts as well.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Study on Reduction of Residual Stress Induced during Rapid Tooling Process: Influence of Heating Conditions on Residual Stress

    Tatsuaki FURUMOTOTakashi UEDAMohd Sanusi ABDUL AZIZAkira HOSOKAWA...
    P.785-789页
    查看更多>>摘要：This paper deals with the reduction of residual stress induced during the selective laser melting with a mixture of ferrous based metal powder. To evaluate the residual stresses induced during layered manufacturing processes, a strain gauge is attached on the bottom face of the base plate. The residual stress within the consolidated structure is calculated from the amount of strain change measured by the strain gauge when the consolidated structure is cut with an end mill. The influences of base plate thickness and consolidated structure height on the residual stresses are investigated. In addition, the effect of pre-heating and post heating by a laser beam irradiation are evaluated. The results showed that the deformation of the base plate increased with the increase of the consolidated layer and the decrease of base plate thickness, and the deformation was flattened when the consolidated structure was completely removed with the end mill. The deformation was related to the induced residual stresses. The residual stress distribution within the consolidated structure in the z direction was extremely large at the top layer of the structure and the boundary between the base plate and consolidated structure. The residual stress at the first layer of the structure decreased when the base plate was heated before consolidating the deposited powder. The residual stresses decreased when each of the consolidated layers was repeatedly heated by the laser beam irradiation.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effects of Molding Parameters and Addition of Fillers on Gate Chip Off Formation During the Degating Process in Transfer Molding

    Abu Bakar SulongGan Tek KeongJaafar Sahari
    P.790-794页
    查看更多>>摘要：In the electronics packaging industry, Epoxy Mold Compound (EMC) polymer matrix is filled with fused silica (SiO_2) to obtain the required roughness and hardness. Gate chip off, which occurs during the degating process in transfer molding is one of the common defects which contributes to the failure in the proper functioning of the package. During the degating process, surface contact between two solid bodies (degating blade and gate) generate a high shear stress on package, thus creating a high potential for the incidence of gate chip of. In this study, the influence of transfer molding parameters and size of fillers (normal and fine) on the gate chip off were investigated. The application of Design of Experiments (DOE) using regression model and Analysis of Variance (ANOVA) showed that molding parameters do not significantly influence the incidence of gate chip off. Numerical simulation was used to investigate effect of two filler sizes and molding parameters on the mold fill time, end pressure of fill and shear stress at the wall. The results showed there were no significant influences on mold fill time but the fine filler showed lower pressure at the end of fill and lower shear stress at the wall. Experimental results of two sizes if filler shown that fine filler mold compound exhibited in reduction of gate chip off formation, compared to normal filler mold compound. Smooth surface of fine mold compound lead to decrease of friction shear stress during degating is expected contribute to this finding.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Driving -A Flexible Manufacturing Method for Individualized Sheet Metal Products

    D. SchererZ. YangH. Hoffmann
    P.795-800页
    查看更多>>摘要：This paper provides general information about the qualification of driving as an on-demand manufacturing concept for the production of individualized sheet metal products. Driving allows the creation of almost any 2D or 3D geometry, but it is a highly interactive, manual production process. Due to the inevitable variations of the incremental forming process (mechanical properties, tribology, wear etc.) and the high number of forming steps, it cannot be automated by traditional approaches. At the Institute of Metal Forming and Casting (Technische Universitaet Muenchen) a kraftformer machine has been equipped with measuring and controlling instrumentation. An optical online measurement system is installed to detect any geometry deformation of the current work piece and to visualize the deviation between the actual and the stored reference geometry during the whole production process. This variance comparison is the first step for planning any following incremental forming actions based on acquired and/or learned knowledge. The second step is the integration of an industrial robot for work piece handling and the automation of the whole manufacturing process. The last step is the integration of neural networks to predict production strategies for any desired unique geometry.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Multi-Axis Control Ultraprecision Micromilling

    Yoshimi Takeuchi
    P.801-805页
    查看更多>>摘要：In recent years, ultraprecision micromachining technology draws wide attention. In particular, multi-axis control ultraprecision machine tools are playing an important role in producing complicated microparts made of a variety of materials. In addition, CAM software is also an essential element to control these machine tools. The paper deals not only with the current state of multi-axis control ultraprecision machine tools but also with the manufacture of two workpieces consisting of complicated shapes by means of micromilling.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Thermal Behavior and Tool Failures on Rotary Cutting of Difficult-to-cut Materials Utilizing Multi Tasking Lathe

    Hiromasa YamamotoKentaro SatakeHiroyuki SasaharaToru Narita...
    P.806-810页
    查看更多>>摘要：In rotary cutting difficult-to-cut materials, less tool wear is observed at higher cutting speeds, contrary to the case of conventional single-point turning. In order to examine this characteristic feature of rotary cutting, this study focuses on the effects of cutting speed and tool peripheral speed on tool failure. Dry rotary cutting tests of stainless steel SUS304 were carried out using coated carbide tools. Cutting speeds were set at 100 m/min, the speed typically recommended for conventional turning, and 500 m/min. At 100 m/min, adhesions and subsequent chippings were observed on the cutting edges. Meanwhile, at 500 m/min the higher average temperature at the tool-workpiece contact area caused small wear spots, rather than adhesions at the optimized tool speed. Hence, for rotary cutting, a higher cutting speed is more effective in terms of both achieving several-times-higher productivity and reducing the amount of tool failure due to the difference of tool failure modes.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Surface Integrity in MQL Drilling Nickel-Based Superalloy

    Erween Abd RAHIMHiroyuki SASAHARA
    P.811-815页
    查看更多>>摘要：Nickel-based superalloys remain the most widely used of all materials in aerospace industry, contributed over 50 % of the weight of a jet engine. In machining of any jet engine components, it is necessary to satisfy the surface quality or surface integrity requirements to facilitate high reliability components. In the present study, surface integrity of Inconel 718 was studied when drilling under different lubricants. The holes were drilled individually using indexable AlTiN coated carbide drill under minimum quantity of lubricant (MQL) conditions. The results demonstrated that the machining conditions and lubricants strongly influence the surface integrity. The surface roughness decreases with the increase in cutting speed and increases with the increase in feed rate. Microhardness profiles indicated that the subsurface deformation extends up to a 100 and 150 μm for palm oil and synthetic ester, respectively underneath the machined surface. Pit holes, cavities, grooves, microcracks and surface smearing were the dominant surface damages criteria for all cases.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effect of Machining Parameters and MQL Liquids on Surface Integrity of High Speed Drilling Ti-6Al-4V

    Erween Abd RAHIMHiroyuki SASAHARA
    P.816-820页
    查看更多>>摘要：Surface integrity is particularly important for the aerospace industry components in order to permit longer service life and maximized its reliability. This present work compares the performance of palm oil and synthetic ester on surface roughness, surface defect, microhardness and subsurface deformation when high speed drilling of Ti-6A1-4V under MQL condition. The drilling tests were conducted with AlTiN coated carbide tool. The surface roughness decreased with increasing in cutting speed and thicker subsurface deformation was formed underneath the machined surface. Grooves, cavities, pit holes, microcracks and material smearing were the dominant surface damages thus deteriorated the machined surface. For both lubricants, the machined surface experienced from thermal softening and work hardening effect thus gave a variation in microhardness values. The results indicated the substantial benefit of MQL by palm oil on surface integrity.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd