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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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    Fretting Fatigue Resistance of Fe- Ni-Cr-Al Coating Prepared by Thermal Spraying subjected to Rotational Bending

    Wei LiuXiangyang XuHuimei ZhaoChuanjing Sun...
    P.475-480页
    查看更多>>摘要：The fretting fatigue experiments of the coated and the uncoated axle specimens were carried out on a test rig simulating assembly loading condition of actual axles and wheels in 1/4 size ratio. The microstructure and Vickers hardness of the coating were examined before and after fretting tests. The results showed that, the thermally sprayed coating, which consisted of lamellar a-(Fe, Cr) and γ-(Fe, Ni) dual-phase microstructure protected the surfaces of specimens from fretting damage. The fretted surface of the coating was covered with an oxide film of Fe and Cr that stopped surface adhesion. The strong work hardening of the coating under the fretted surface could prevent fretting cracks from vertically propagating and hinder nucleation of fatigue cracks in the specimen substrate. As a result, the fatigue strength of the coated specimen was increased more than 50%.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effects of Substrate Bias Voltages on the Erosion Wear Resistance of TiN Coatings Deposited by Pulsed Filtered Vacuum Cathode Arc Deposition

    Fengfang WuJianxin DengPei Yan
    P.481-486页
    查看更多>>摘要：TiN coatings were produced on substrates of a hard metal at different bias by pulsed filtered vacuum cathode arc deposition assisted with ion bombardment. The erosion wear resistance of TiN coatings was investigated. The erosion wear was tested with a gas blast apparatus. In the test, TiN coatings were impacted at an impingement angle of 90° by angular SiC solid particles with an average diameter of 124um. The maximum depth of the erosion scar measured by the Veeco NT9300 optical profiler was used to evaluate the erosion wear loss of the coatings. The coatings proved to have lower erosion rate than the substrate material and consequently, the erosion rate increased significantly to the high level of the hard metal substrate after the coatings were penetrated. The results indicated that the TiN coating deposited at 150V bias had the lowest erosion wear rate and best wear resistance. The failure mechanism was revealed by examining the surface morphology of the coatings before and after the erosion test. The erosion wear of the TiN coatings behaved as typical brittle materials.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Development of Nano Crystalline Nickel Coating for Engineering Applications

    Srivathsan RaviKarthick Venkatesh GaneshArunachalam RamanathanJegan Annamalai...
    P.487-492页
    查看更多>>摘要：The current research focuses on developing nano-crystalline nickel coating for engineering applications through pulse plating technique. Based on the literature survey, the current density, duty cycle and frequency were identified as important grain refining parameters. Coating was done over a mild steel sample after mechanical polishing, vapour degreasing and anodizing. Experiments were conducted using the three determining parameters and their influence on the properties of the coating was evaluated. Coatings were then characterized for the surface morphology and hardness. The XRD analysis for the surface morphology resulted in the grain size of 19 nm and the hardness measured from the microhardness tester was 677 HV which is higher than the hardness reported in the available literatures. The influence of the pulse plating parameters on the grain size and hardness of the coating has been listed out for the benefit of the scientific community.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Coating of Polythiophene by Microwave Plasma Polymerization Process

    Boonchoat PaosawatyanyongPhensupa KamphiranonWorawan Bhanthumnavin
    P.493-498页
    查看更多>>摘要：This research is focused on improving electrical conductivity of conjugated polythiophene films fabricated by microwave plasma assisted polymerization process. Polythiophene thin films with 300 nm to 1.5 micron thickness were deposited on glass substrates in a highly uniform fashion as evident by Scanning Electron Microscopic analysis. An efficient incorporation of the iodine dopant into the films was also successfully performed to give thin films with 120-250 nm thickness. The films were characterized by various spectroscopic methods. Attenuated total reflectance-Fourier transform infrared spectroscopy showed absorption frequencies of important functional groups mostly characteristics of thiophene. The doped fabricated films exhibited UV-vis spectra indicative of increased π-conjugation (439-535 nm). Results from energy-dispersive X-ray spectroscopy confirmed the presence of iodine in the films of upto 10%. Electrical conductive measurements revealed that the undoped films has the conductivity in the range of 1.4×10~(-5) to 1.0×10~(-4)S/cm.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Wear Behavior of the CVD and PVD Coated Piercing Punch

    Pakorn ChumrumVarunee Premanond
    P.499-503页
    查看更多>>摘要：The purpose of this work is to investigate the effectiveness of PVD and CVD process of TiCN film coating on SKH51 JIS tool steel on reducing wear in piercing operation. Both processes of PVD and CVD were carried out under commercial conditions. It was found that the amount of wear found for TiCN-PVD coated punch is lower than that of CVD coated punch. Adhesive strength of film coated by CVD technique is found lower which is related to photograph taken from SEM show major adhesive wear.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Sputter-Deposited ZrO_2 Gate Dielectric on High Mobility Epitaxial- GaAs/Ge Channel Material for Advanced CMOS Applications

    Goutam Kumar DalapatiAvishek KumarAndrew See Weng WongManippady Krishna Kumar...
    P.504-509页
    查看更多>>摘要：Sputtered-deposited ZrO_2 gate dielectric on epitaxial-GaAs/Ge substrates have been studied for complementary-metal-oxide-semiconductor (CMOS) applications. The epitaxial-GaAs (epi-GaAs) on Ge susbstrates with AlGaAs interlayer was grown by metal-organic chemical vapor deposition at 650℃. High resolution transmission electron microscopy ((HRTEM) shows that the epilayers are free from arsenic anti-phase defects (APD). From secondary ion mass spectrometry, it was confirmed that the Ge diffusion is completely blocked by the AlGaAs layer and no Ge atoms are able to penetrate into the GaAs layer. The macroscopic surface roughness of epitaxial GaAs is ～5.3nm, whereas over 200×200nm is 0.4 nm, which is comparable with bulk GaAs. Althogh, the epi-GaAs has nano-scale surface features; the conduction-AFM shows electrically homogeneous surface. The electrical and interfacial properties of MOS capacitors with sputtered deposited ZrO_2 dielectric on epitaxial-GaAs/Ge and bulk GaAs substrates were investigated. The frequency dispersion and hysteresis voltage for directly deposited ZrO_2 on epi-GaAs is higher compared with bulk p-GaAs, however, it is comparable with bulk n-GaAs. The interfacial and electrical properties of ZrO_2 on epi-GaAs have shown to exhibit better electrical characteristics after post deposition annealing (PDA) at 400℃. The apparent doping profile of the epitaxial layer is unchanged with PDA temperatures, which suggest the less cross-diffusion of Ge, Ga, and As during device fabrication. The degradation of the gate oxide quality and interface properties are mainly due to the high surface roughness of epitaxial layer and also presence of elemental out diffusion of Ga and As.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Nitrogen and Bias Effect on Homoepitaxial Diamond Growth by Hot-Filament Chemical Vapor Deposition

    Hung-Yin TsaiChih-Cheng ChangChin-Wei Wu
    P.510-515页
    查看更多>>摘要：The development of homoepitaxial films for advanced device applications has been studied, but high growth rate and diamond film quality have not yet been explored. In the current study, high quality homoepitaxial diamond films were grown on type Ib (100) HPHT synthetic diamond substrate by hot-filament chemical vapor deposition. The reactant gases were mixed by CH_4 and H_2 with small amounts of N_2 (500 to 3000 ppm). Besides, a bias system was used to assist diamond film deposition. The pyramidal crystals on diamond surface can be suppressed and high quality diamond film of FWHM (Full Width at Half Maximum) = 10.76 cm~(-1) with high growth rate of 8.78 ± 0.2 μm/ hr was obtained at the condition of adding 1000 ppm nitrogen. At the bias voltage of-150 V, the pyramidal crystals can also be suppressed and high quality diamond film of FWHM = 10.19 cm~(-1) was obtained. With nitrogen addition above 2000 ppm, diamond film was partly doped and some sp~2 structures appeared. These homoepitaxial diamond films were characterized by optical microscopy and micro-Raman spectroscopy.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Major Factors in Rapid Prototyping of Mechanisms

    Yonghua ChenZhezheng Chen
    P.516-521页
    查看更多>>摘要：Nowadays, layer based rapid prototyping (RP) technologies have been used not only to make product prototypes but also to manufacture small batch functional parts. For RP parts fabrication, build directions play an important role. There were many reports about optimal build directions for RP part fabrication, yet factors influencing build directions of mechanism joint have not been studied. This paper will look into the factors affecting build directions of mechanisms. A slider-crank mechanism is used as an example as it is the fundamental mechanism for many machine designs. Apart from factors affecting mechanism build directions, guidelines for mechanism joint design are also discussed.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Rapid Prototyping STL Reconstruction for CT Medical Image in Fused Deposition Modelling

    Chung-Shing WangTeng-Ruey ChangWei-Hua A. WangMan-Ching Lin...
    P.522-527页
    查看更多>>摘要：The main objective of this research is to reconstruct 3D rapid prototyping (RP) models for computer tomography (CT) medical images in fused deposition modeling (FDM). It demonstrates a technique to convert medical images to points cloud, and simplify into STL (Stereo-Lithography) triangular meshes for RP machine in fused deposition modelling. The grey prediction algorithm is used to sort contour point data in each layer of the medical image. The contour difference detection operation is used to sequence the points for each layer. The 3D STL meshes are then constructed by layer-by-layer sequence meshes algorithm to build the STL file. Once this STL file is saved, a 3D physical model of the medical image can be fabricated by FDM RP manufacturing, and its virtual reality model can also be presented for visualization. CT images of a human skull and femur bone were used as the case studies for the construction of the 3D solid model with medical images. The STL models generated using this new methodology compared to commercial computer-aided design (CAD) models. The results of this research are therefore clinically reliable in reconstructing 3D STL models for CT medical images.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Fabrication Inner Channel Ceramics Using Layer Additive Method

    Fwu-Hsing LiuWen-Hsueng LinYung-Kang ShenJeou-Long Lee...
    P.528-533页
    查看更多>>摘要：This paper presents a layer additive method, ceramic laser curing, to form a ceramic part with inner channel features, by which silica powder is bonded by curing effect under disposal of a 20W CO2 laser. This process includes four steps: making slurry by mixing a binder with ceramic powder, paving the slurry on the surface of a platform, scanning the paved slurry layer via laser beam, removing the un-cured slurries from the solidified ceramic component. This process needed only low laser power to build ceramic parts by using "curing effect". The deflection and shrinkage of ceramics could be decreased, also the distortion due to post sintering process was avoidable. The inner channel structures were support by ceramic slurries to avoid the sagged deflection and to maintain the dimensional accuracy. The maximum flexural strength of the cured specimen was 4.7 MPa. This process has potential to fabricate inner complex ceramic components for industrial applications.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd