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Key engineering materials
Trans Tech Publications Ltd.
Key engineering materials

Trans Tech Publications Ltd.

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1013-9826

Key engineering materials/Journal Key engineering materials
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    Ultrasonic Surface Mechanical Attrition of Commercially Pure Ti to Induce Nanocrystalline Surface Layer

    M. MansoorJ. Lu
    P.152-157页
    查看更多>>摘要：In the domain of incremental nanotechnology, surface mechanical attrition treatment is a technique which can transform superficial structure of a material to nanocrystalline without changing the chemical composition. This study is a part of the development and implementation of the technique by using ultrasonic vibrations. The material used is pure titanium in rolled and annealed condition. The nanocrystalline structure is characterized using X-ray diffraction (XRD), and transmission electron microscopy (TEM). The measured grain size is in the order of 5～60 nm. A correlation in the results of XRD and TEM is also discussed.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Impact of Metal-Organic Interface on the Growth Mechanism and Magnetic Properties of Permalloy (Fe : Ni) Films Sputtered on Self-Assembled Monolayers of Polar and Nonpolar Molecules

    S.N. AhmadG.F. StrouseS.A. Shaheen
    P.158-163页
    查看更多>>摘要：Metal deposition on self-assembled monolayers (SAMs) with different terminal organic functional groups is a growing area of research and the metal-organic interface has been extensively studied in the past two decades. Apart from impacting existing technologies, it may have a profound impact on the emerging future technologies such as molecular electronics. The morphology of the deposited metals is strongly influenced by the nature of the chemical interactions occurring at the interface of the organic functional group (OFG) of the SAM and the deposited metal. Our interest for such studies stems from different perspective, as we are interested in determining the impact of the interface on the morphology and hence the magnetic properties of the deposited magnetic materials. We have sputtered a magnetic material, permalloy (Ni_(79)Fe_(21)), on self-assembled monolayers of polar and nonpolar molecules, and have observed contrasting magnetic behaviors of permalloy on these surfaces. We have observed the formation of uniform film on polar regions and cluster are formed on nonpolar regions. Further investigations reveal that the cluster formation gives rise to superparamagnetism, while the uniform film shows a usual ferromagnetic behavior. The observed contrast in morphology and magnetism of Py is attributed to different growth mechanisms arising from difference in polarity of the SAM surfaces.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Estimation of the Hardness for Laser Surface Hardening of Plain Carbon Steel

    M.M. AshrafA. HussainR. AkhterW.A. Farooq...
    P.164-171页
    查看更多>>摘要：Laser surface hardening of plain carbon steel is simulated and software in Mathematica has been developed. The software estimates the hardness of plain carbon steel under different carbon contents and processing speeds. The flow chart explains the algorithm of the software. Our results show that hardness increases with carbon contents. The hardness increases slightly with processing speed but at the cost of decrease in hardened depth. The results for test material coincide with the experimental values from independent research results.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Parametric Study of Ablation Depths for Different Optical Glasses Using High Fluence Laser Induced Plasma Assisted Ablation (LIPAA)

    A.H. HamdaniW. AhmedA. AnsarR. Akhter...
    P.172-177页
    查看更多>>摘要：A 40W Nd:YAG laser has been used to carry out parametric study the etching depth (ablation depth) for different optical glasses using stainless steel, brass and silver as target materials by Laser Induced Plasma Assisted Ablation (LIPAA) process. A maximum ablation depth of 38μm for fused quartz has been achieved with stainless steel as target material with a high ablation rate of 565nm/pulse. A surface roughness of 120nm has been measured for fused quartz with stainless steel as target.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Optical and Structural Analysis of GeC Thin Films Deposited by Reactive Pulsed Laser Ablation Technique

    H.Z. ShafiA. MahmoodZ. AliM. Mahmood...
    P.178-186页
    查看更多>>摘要：GeC thin films have been prepared by reactive pulsed laser ablation technique. Methane pressure (P_(CH4)) was varied from 0 to 75 milli torrs (mT). Optical analysis of all the samples was performed by spectroscopic ellipsometry (SE). The optical constants i.e. refractive index (n), extinction coefficient (k), absorption coefficient (a) and thickness of deposited film(s) were obtained by modeling and simulations of ellipsometric data. It was found that deposition parameter (change in pressure of methane) has a profound effect on the properties of the deposited films. To support our results of optical analysis, other important diagnostic techniques like atomic force microscopy (AFM), Fourier Transform Infrared Spectroscopy (FTIR) etc. were employed.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Development of Wear Resistant Nano Dispersed Composite Coating by Electrodeposition

    R.K. SahaI.U. HaqT.I. KhanL.B. Glenesk...
    P.187-194页
    查看更多>>摘要：This study concerns the development of wear resistant coatings of Ni-Al_2O_3 composite on steel substrates by electrodeposition. Each of the coating experiments was performed in an electrolytic bath, containing a nano-sized dispersion of Al_2O_3 particles in nickel sulfate and boric acid solution. Composition of the coating mixture was systematically varied with respect to the contents of the dispersed particles, while the amount of the dissolved nickel sulfate, and boric acid and the applied current were kept constant during the experimental measurements. The coated substrates were characterized for their morphology, Vickers hardness, and scratch resistance properties. It was observed that hardness and scratch resistance of the coated substrates increased with an increase in the Al_2O_3 content in the coating. It was noted that hardness of the composite coating decreased after heat treatment at 400℃ in air atmosphere.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    New Trends in Wide Bandgap Semiconductors: Synthesis of Single Crystalline Silicon Carbide Layers by Low Pressure Chemical Vapor Deposition Technique on P-Type Silicon (100 and/or 111) and their Characterization

    F. IqbalA. AliA. MehmoodM. Yasin...
    P.195-201页
    查看更多>>摘要：We report the growth of SiC layers on low cost p-type silicon (100 and/or 111) substrates maintained at constant temperature (1050 - 1350℃, △T=50℃) in a low pressure chemical vapor deposition reactor. Typical Fourier transform infrared spectrum showed a dominant peak at 800 cm~(-1) due to Si-C bond excitation. Large area x-ray diffraction spectra revealed single crystalline cubic structures of 3C-SiC(111) and 3C-SiC(200) on Si(111) and Si(100) substrates, respectively. Cross-sectional views exposed by scanning electron microscopy display upto 104 μm thick SiC layer. Energy dispersive spectroscopy of the layers demonstrated stiochiometric growth of SiC. Surface roughness and morphology of the films were also checked with the help of atomic force microscopy. Resistivity of the as-grown layers increases with increasing substrate temperature due to decrease of isolated intrinsic defects such as silicon and/or carbon vacanies having activation energy 0.59 ±0.02 eV.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Analysis of Material Coating for Damping in Beam Structures

    S.H. RazaM.A. MalikW. Akram
    P.202-210页
    查看更多>>摘要：Vibratory stresses are the main cause of material failure in aerospace/mechanical structures and machine components. Failure also occurs due to these vibratory stresses in gas turbine engines and rotating machinery components while operating at resonant frequency. A magnetomechanical coating material is used as a very effective method for damping of these stresses. Vibratory stress damping in components like turbine blades through magnetomechanical coating material is well known in literature. However, the geometric correlations for the varying coated beam are not well established. We have utilized a cantilever beam as the basic geometry for this investigation to establish a correlation for varying coating. Beam theory is applied as a mathematical model for obtaining the mode shapes for the beam. A finite element procedure is performed to acquire the data and this data is then correlated with beam theory model for initial verification. This data is further evaluated to form the required model for calculating thickness of coating for a beam. The resulting parametric correlation is verified through comparison with the already published experimental data available in literature. This correlation can be used as a design tool for suppression of vibratory stresses in industrial applications.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Study of the Effect of Coating Thickness, Substrate Temperature and Biasing Voltage on Various Characteristics of AlN Film

    F. AliA.M. QasimS. ImranM. Mehmood...
    P.211-220页
    查看更多>>摘要：AlN thin films have a wide range of applications in electronic devices. AlN thin films are used as a protective coating of thermo printing devices and also as a material of cold cathodes. Moreover, these thin films are the most promising piezoelectric materials for surface acoustic wave (SAW) applications. In this work, thin films of AlN were grown on glass and MS substrates by reactive DC magnetron sputtering. The crystallographic and micro-structural properties of sputtered AlN films were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The films were found to be having hexagonal crystalline AlN structure in all cases irrespective of deposition parameters. However, Al peaks were also observed showing simultaneous metallic layer deposition. Grain growth was observed with increase in film thickness. Biasing resulted in better adhesion of the nitride film with the substrate. Hardness measurements were also made for different deposition parameters, but less significant changes were observed.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    The Influence of Si Additive on Structural and Microstructural Properties of Cu-Zn Ferrite System

    Uzma GhazanfarG. Abbas
    P.221-226页
    查看更多>>摘要：Mixed Cu-Zn ferrites (for x = 0.66 to 0.99) are prepared by the double sintering ceramic method. Locally available low cost Fe_2O_3 with 0.5wt% of Si additive is used for this purpose which reduced the process price markedly and improves the properties of the ferrite produced. The chemical phase analysis carried out by X-ray powder diffraction method confirms the major phase of Cu-Zn ferrite structure. Lattice parameters, X-ray density and mass density along with porosity have been investigated to study the effect of composition. Lattice parameters shows a decreasing trend with increasing Cu content, x. whereas, both X-ray density and mass density increases with increasing x, which in turn decreases the porosity due to successive presence of Si in Fe_2O_3. This decrease in porosity along with chemical homogeneities, distribution of phases and grain formation were also observed from Scanning electron micrographs at different magnifications.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd