首页期刊导航|Key engineering materials
期刊信息/Journal information
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
正式出版
收录年代

    Electrochemical Nanostructuring of Semiconductors by Capillary-Cell Method

    Y.T. TaurbayevK.A. GoncharA.V. ZoteevV. Yu. Timoshenko...
    P.1-6页
    查看更多>>摘要：Wafers of silicon and compound semiconductors are nanostructured by using electrochemical or chemical etching (stain etching) in etching cell with electrolyte kept by capillary forces. Atomic force microscopy, infrared spectroscopy and Raman scattering methods reveale nanoporous and nanocrystalline structure of the treated surfaces. The formed porous semiconductors demonstrate efficient photoluminescence, which is controlled by etching parameters, i.e. current density, electrolyte content, etc. These results indicate good prospects of the employed capillary-cell method for preparing nanostructured porous materials with desired structure and optical properties.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Inkjet Printing of Catalyst-Inks on Si Wafers and the Subsequent Synthesis of Carbon Nanotubes by Chemical Vapour Deposition

    M. MansoorI. KinlochB. Derby
    P.7-14页
    查看更多>>摘要：The production of substrates coated with carbon nanotubes (CNTs) in well-defined patterns is desirable for sensor applications. In the present work, nickel based catalytic inks were prepared and printed on silicon substrates using inkjet delivery. Subsequently, the substrates were subjected to calcination and chemical vapour deposition for the growth of aligned CNTs. Scanning electron microscopy, transmission electron microscopy and Raman spectroscopy were used to characterize the CNTs. Various concentrations and formulations of ink preparations were studied to investigate the effect of these parameters on the growth and structure of the CNTs.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effect of Zr Addition on the Mechanical Behavior, Ductility and Wear Resistance of Aluminum Grain Refined by Titanium

    A.I.O. ZaidS.M.A. Al Qawabah
    P.15-25页
    查看更多>>摘要：Aluminum and its alloys are the second most commonly used metal for a variety of engineering applications. They solidify in columnar structure with large grain size which normally affects their mechanical behavior and surface quality. It is now becoming customary in aluminum foundry to grain refine their structure by adding either titanium or titanium + boron to their melt before solidification.In this paper, the effect of addition of Ti on the mechanical properties, ductility and wear resistance of commercially pure aluminum is investigated. Titanium was added at a level of 0.15 % wt. This ratio corresponds to the peritictic limit on the Al-Ti phase diagram and is normally used for grain refining of aluminum. It was found that addition of Ti at this level resulted in grain refinement of aluminum structure whereas addition of Zr alone resulted in grain coarsening of Al structure while it resulted in grain refinement when it is added in the presence of Ti. Regarding the effect of Zr on the wear resistance of aluminum it was found that at small loads and speeds addition of Ti or Zr or both together resulted in deterioration of its wear resistance whereas at higher loads and speeds resulted in pronounced improvement of its wear resistance.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Diffusion Bonding of Austenitic Stainless Steel 316L to a Magnesium Alloy

    W. ElthalabawyT.I. Khan
    P.26-33页
    查看更多>>摘要：Dissimilar metal combinations are often necessary when manufacturing a component in order to meet particular functional and engineering requirements or protect against environmental degradation. Stainless steels are used in a diverse range of applications due to their excellent corrosion resistance, formability and strength. The 316L stainless steel also shows good crashworthiness due to its high strain rate sensitivity which makes it suitable for the transportation industry. The joining together of the 316L steel and AZ31 magnesium alloy cannot be achieved using conventional fusion welding methods and therefore, diffusion bonding using interlayers was used to overcome the differences in their physical properties. The results show that Cu and Ni interlayers form a eutectic with the magnesium which enhances wettability and bond formation through isothermal solidification. The effect of hold time on the microstructural developments across the joint region was studied at a bonding temperature of 530℃ and 510℃ for the Cu and Ni interlayers respectively using a bonding pressure of 0.2 MPa. This preliminary investigation shows that by increasing the bonding time from 5 to 60 minutes results in a Cu-Mg and Ni-Mg eutectic phase structure forming along the bond interface. By holding the joint at the bonding temperature for 15 minutes initiates isothermal solidification of the joint and this was confirmed by DSC analysis. However, the movement of the solid/liquid interface on solidification pushes intermetallic phases into the center of the bond during the solidification stage. The intermetallics increase the hardness value of the bond interface and lower final bond strengths.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Transpiration Cooling Assisted Ablative Thermal Protection of Aerospace Substructures

    M.B. KhanN. IqbalZ. Haider
    P.34-40页
    查看更多>>摘要：Ablatives are heat-shielding materials used to protect aerospace substructures. These materials are sacrificial in nature and provide protection primarily through the large endothermic transformation during exposure to hyper thermal environment such as encountered in re-entry modules. The performance of certain ablatives was reported in terms of their TGA/DTA in Advanced Materials-97 (pp57-65) (1). The focus of this earlier research resided in the consolidation of interface between the refractory inclusion and the host polymeric matrix to improve thermal resistance. In the present work we explore the scope of transpiration cooling in ablative performance through flash evaporation of liquid incorporated in the host EPDM (Ethylene Propylene Diene Monomer) matrix. The compression-molded specimens were exposed separately to plasma flame (15000 C) and oxyacetylene torch (3000 C) and the back face transient temperature is recorded in situ employing a thermocouple/data logger system. Both head on impingement (HOI) and parallel flow (PF) through a central cavity in the ablator were used. It is observed that transpiration cooling is effective and yields (a) rapid thermal equilibrium in the specimen, (b) lower back face temperature and (c) lower ablation rate, compared to conventional ablatives. SEM/EDS analysis is presented to amplify the point.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Processing, Characterization and Properties of Specially Constituted Zr-Based Bulk Amorphous Alloys

    M. IqbalJ.I. Akhter
    P.41-51页
    查看更多>>摘要：Bulk metallic glasses (BMGs) are an emerging class of materials. The amorphous alloys have very attractive properties. There is potential for applications. The quaternary and pentanery (ZrCuAlNi)_(100-x)Ti_x (x = 0, 2 and 5 at. %) alloys were synthesized by melting 2-3N pure metals in an arc furnace. Amorphous ingots were produced using Cu mold casting technique. The alloys showed wide supercooled liquid region △T_x, high thermal stability and good glass-forming ability (GFA). Many thermal parameters like T_(rg), γ, δ, β and ω were measured employing high temperature differential scanning calorimetry (DSC). Structural characterization was carried out by X-ray diffraction (XRD) technique. Microstrucrural characterization was conducted using high resolution field emission scanning electron microscopy (FESEM) and elemental analysis was done using energy dispersive spectroscopy (EDS). Crystallization behavior and phase formation was studied. Activation energy for crystallization was calculated using Kissinger and Ozawa equations. The alloys show double stage crystallization. Mechanical properties were measured. Compression test was carried out and fracture strength and strain were determined. The fracture behavior was studied which showed veins like patterns, shear bands formation and liquid droplets.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effect of Heat Sinks on Visco-Elastic & Mechanical Properties of EPDM Based Ablative Composites

    M.A. BashirH. AhmadR. AhmedR.A. Alvi...
    P.52-58页
    查看更多>>摘要：Ablative composites are heat shielding, protective materials that are being used in aerospace industry to protect inner hardware and sensitive devices. The aero dynamic vehicles have to face high stresses, ultra high temperature and adverse conditions of air friction. It is required to develop the materials with light weight and high modulus. EPDM, being heat and ozone attack resistant is the best candidate for the preparation of ablative composites by introducing different heat sinks such as silica, glass fiber, carbon fiber, asbestos, carbon and their combinations have been studied in this work.The prepared materials were tested and it was found that visco elastic behavior of the composites affected by the addition of reinforcing filler (carbon, silica), semi-reinforcing filler (carbon fiber, glass fiber) and non-reinforcing filler (asbestos powder). Mechanical properties tested at different rates, revealed the improvement in tensile strength and % elongation in case of reinforcing and semi-reinforcing fillers but showed adverse effect in case of non-reinforcing fillers. Rheological investigations of these novel composites shows that moony viscosity of the materials containing glass fiber, carbon fiber, silica decreases in the order glass fiber > carbon fiber > silica.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effect of Vacuum Arc Melting/Casting Parameters on Shrinkage Cavity/Piping of Austenitic Stainless Steel Ingot

    J. KamranM. SarwarM. Feroz
    P.59-65页
    查看更多>>摘要：Shrinkage cavity/piping at the end of the solidified ingot of steels is one of the most common casting problem in 316L austenitic stainless steel ingot, when consumable electrode is melted and cast in a water-cooled copper mould by vacuum arc re-melting furnace. In present study an effort has been made to reduce the size of shrinkage cavity/ piping by establishing the optimum value of hot topping process parameters at the end of the melting process. It is concluded that the shrinkage cavity/piping at the top of the solidified ingot can be reduced to minimum by adjusting the process parameters particularly the melting current density.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Transient Liquid Phase Bonding of High Strength Low Alloy Steel Coiled Tubing

    A. JavadzadehT.I. Khan
    P.66-73页
    查看更多>>摘要：The oil and gas industry of Alberta, Canada use coiled tubing made from high strength low alloyed steel (HSLA) to extract oil from reservoirs deep beneath the earth's surface. The repeated use of the coiled tubing in down-hole wells results in fatigue failure of the tube material. In order to repair the coiled tube, a section of tubing is fusion welded using tungsten inert gas welding onto the remaining tube steel. However, the fusion weld often fails within the weld region and therefore, alternative joining methods need to be explored to minimize detrimental changes at the joint region. In this study transient liquid phase (TLP) bonding is used with the aid of metal interlayers based on the Ag-Cu and Ni-P systems. These interlayers form a liquid at the melting point and the gradual diffusion of alloying elements into the joint and the diffusion of elements out of the joint region induces isothermal solidification whilst the joint is held at the bonding temperature. The TLP bonding behaviour of the HSLA steel as a function of bonding parameters was investigated and the quality of the joint region determined using metallurgical techniques (light and scanning electron microscopy, energy dispersive spectroscopy) and mechanical testing.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Microstructural Characterization of Silicon Added Titanium Aluminide

    A. Nusair Khan
    P.74-80页
    查看更多>>摘要：Titanium aluminides intermetallic compounds have received great attention during the past decade, since they have the potential, in aircraft and automotive engines, to replace the high density Ni-base superalloys However, these intermetallics possess poor oxidation properties at high temperatures. Previous studies showed that protective alumina scale formation on γ-TiAl can be obtained by small additions (around 2 at.%) of Ag. In the present study, a number of cast Ti-AI-Si alloys were investigated in relation to transient oxide formation in air at 1300℃. After various oxidation times the oxide composition, microstructure and morphology were studied by combining a number of analysis techniques. The TiAl-Si alloys appear to form Al Ti and Si oxides. However, the formation of silicon oxide at the interface of base metal and scale slows down the oxidation rate significantly.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd