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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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    Effect of Cu on Structural and FF-Behavior of NiTi Shape Memory Alloy

    S. RaniM.S. AwanI.N. QureshiF. Yasmin...
    P.301-308页
    查看更多>>摘要：The functional fatigue behavior of Ti_(50)Ni_(30)Cu_(20) (at. %) shape memory alloy was investigated after subjecting to cold working and heat-treatment. Copper addition modified the phase transformation behavior with the introduction of B_(19)-phase in the binary NiTi alloy. It was observed that aging after annealing and thermal cycling (-60 to 100)℃ significantly effect the transformation temperatures. Observations in optical microscope and scanning electron microscope reveal inhomogeneity in the composition in the form of coarse Cu+Ti-rich precipitates. Investigations under transmission electron microscope showed growth of internally twined martensitic plates in solution treated sample. The phase transformation temperatures were determined with differential scanning calorimeter. The transformation temperatures were shifted towards lower side. Dislocations introduced during cold working and fine precipitation after aging, may be responsible for this change in the transformation characteristics of the material.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    A Novel Fabrication Method for Nitinol Shape Memory Alloys

    S.A. RizviT.I. Khan
    P.309-315页
    查看更多>>摘要：Nitinol (NiTi) shape memory alloys are widely used in a variety of biomedical applications, such as dental implants, cervical and lumbar vertebral replacements, joint replacements and stents. In this study, commercially pure Ti and Ni foils ～100 um thick were diffusion bonded in vacuum. The experimental conditions were optimized to achieve a near equiatomic composition to produce NiTi SMA thin foil of approx. 5-8 micron thick. The cross-sectional surfaces of joint were subjected to metallographic investigation using optical microscope after grinding, polishing and etching. Scanning electron microscope equipped with EDX system was utilized to characterize the bonded layer and compositional analysis. Differential scanning calorimetry (DSC) technique was employed to determine the shape memory effect. The samples were subjected to X-ray diffraction analysis in order to establish phase structures formed during the diffusion bonding stage. An ultra fast femto-second laser facility was utilized to ensure the production of complex shapes or patterns within micron scale.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Evaluation of Phase Transformation in Manganese Steels by Eddy Current Method

    S.H. KhanA. Nusair KhanK. Mahmood
    P.316-321页
    查看更多>>摘要：An investigation was conducted to explore the applicability of eddy current nondestructive evaluation technique for the characterization of manganese steels. Specimens of two different types of manganese steels were subjected to various compression loads. The specimens were then evaluated by mechanical and eddy current testing. The hardness and eddy current values were increased due to conversion of austenite to martensite. In this study the correlation between eddy current parameters and compression load was discussed.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    The Effect of Sn on the Impedance Behaviour of Al-Zn Alloys in Natural Chloride Solution

    M.C. IsaM.Y. AhmadA.R. DaudM. Daud...
    P.322-329页
    查看更多>>摘要：Electrochemical behaviour of cast Al-Zn alloys in natural chloride solution were investigated by potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). Results from open circuit potential (OCP) measurement against immersion time showed a stable free corrosion process was achieved after 15 kiloseconds and alloys with more Sn contents had shifted OCP value towards more negative direction. Potentiodynamic polarisation curves showed that the corrosion potential (E_(corr)) of aluminium alloys with Sn addition were much active compared to alloy without Sn. The anodic curves were characterized by no sign of passive current due active dissolution on the surface of the Al-Zn-Sn alloy. SEM images show that the presence of Sn in Al-Zn alloys produces better and uniform dissolution morphology. EIS results confirm that the presence of Sn is beneficial in improving anodic dissolution of Al-Zn alloys by reducing resistance to polarization (R_p). The presence of 0.1 %wt. Sn in Al-Zn alloy has been found to be useful in activating electrochemical reaction at alloy-solution interface based on inductive loop in EIS diagram.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Metallurgical Characterization of Duplex Steel by Non Destructive Techniques

    S.H. KhanA. Nusair KhanK. Mahmood
    P.330-334页
    查看更多>>摘要：This paper describes the application of eddy current and ultrasonic velocity technique for the study of cold rolled duplex steel. Samples are cold rolled up to 80 percent and then tested for X-Ray diffractrometeric analysis, hardness testing, ultrasonic longitudinal velocity and for eddy-current testing. It was observed that eddy current impedance and longitudinal velocity is affected due to variation in micro-structure induced by cold working. It is suggested that eddy current and ultrasonic velocity techniques are useful tools for the characterization of duplex steel during cold working operation.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Improvement in Mechanical Properties of High Concentration Particle Doped Thermoset Composites

    N. AhmedM.B. Khan
    P.335-341页
    查看更多>>摘要：The paper relates to high concentration particle doped composites based on thermosetting polymer systems in which the sequential addition of particles of certain size distribution is followed by curing and casting of the slurry to form a thermoset composite. Conventionally, at a threshold of beyond 90% of particles by weight of the polymer using triglyceride, the mechanical properties of the composite exhibit a sharp decline. The present research mitigates this behavior by incorporating a unique combination of cross-linking agents in the base polymer to impart exceptional mechanical properties to the composite. More specifically, the base polymer consists of butadiene, with triglyceride as cross-linking agent together with hydroxy-alkane as the chain extension precursors, when tune to the appropriate level of hard segment ratio in the polymer. An added advantage according to the present work resides in the analytical nature of butadiene pre-polymer as opposed to natural product; traditional composites based on natural sources are hampered by their inconsistent chemical composition and poor shelf life in the fabricated composite. The thermoset composite according the present research exhibits superior tensile strength (200-300 psi) properties using particle loading as high as 92% by weight of the fabricated composite as measured on a Tinius Olsen machine. Dynamic Mechanical Testing reveals interesting combination of storage and loss moduli in the fabricated specimens as a function of optimizing the thermal response of the viscoelastic composite to imposed vibration loading.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effect of the Fillers Contents on the Chemical, Mechanical and Thermal Properties of Polymer Composites

    A. QuddosS.M. HussainHafiz-ur-RehmanT. Abbas...
    P.342-348页
    查看更多>>摘要：Polymer composites are used in numerous applications. In spite of this fact, new developments are still under way to explore in other field of application of these materials and to tailor their properties for more extreme condition. A particular emphasis is focused on fillers content is summarized. Some steps towards the functionally graded materials are illustrated. The FT-IR spectroscopic studies revealed the information about curing of epoxy with fillers. It was observed that mechanical properties like tensile strength, hardness etc get enhanced up with filler contents. The effect of the different formulations were investigated and discussed for optimum process condition.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Thermal and Electrical Conductivities of Carbon Fibers and Carbon Nanotubes Incorporated Polyurethanes Composites

    S.A. AbdullahL. FrormannA. Saleem
    P.349-355页
    查看更多>>摘要：Single filler polyurethane composites with carbon fibers (CFs) and multi-walled carbon nanotubes (MWNTs) were prepared by melt mixing methods and its thermal as well as electrical resistivity characteristics were investigated. The influences of fillers and mixing methods on thermal and electrical conductivity of CF/- and MWNT/polyurethane composites were investigated and the result shows that the addition of carbon fillers improved the thermal conductivity of the polyurethane composites. Higher filler concentration results in better thermal conductivity because better formation of thermally conductive networks along polymer matrix to ensure the thermal was conducted through the matrix and the network along the polymer composites. The presence of carbon additives improves the electrical resistivity of the materials as well. The present study revealed the potential of carbon as agent for better thermal and electrical conductivities and their properties depend strongly on the dispersion and distribution of the fillers in the polymer matrix.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Investigation of Electrical Properties of Polyaniline Nanocomposites by Impedance Spectroscopy

    A.B. AfzalM.J. AkhtarM. NadeemM. Masood-ul Hassan...
    P.356-363页
    查看更多>>摘要：Polyaniline (PANI) nanocomposites were synthesized by incorporating separately synthesized metal nanoparticles in 1-methyl-2-pyrrolidinone (NMP) solution of polyaniline. PANI was prepared by oxidative reduction of aniline using chemical method. Silver nanoparticles were produced by inert gas condensation; whereas gold nanoparticles were synthesized by the reduction of gold salt. FTIR confirmed the formation of PANI in all samples. The electrical properties of the nanocomposites were determined by impedance spectroscopy. The conductivity relaxation analysis suggested microphase separation of NMP plasticized films into phases of reduced and oxidized repeat units. The conductivity of PANI films increases with the increase in concentration of embedded nanoparticles. Incorporation of metal nanoparticles in PANI causes considerable decrease in the real part of impedance.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Deposition and Characterization of CdSe Nanoparticles in Polymeric Materials

    A. QuddosM.B. KhanA. WadoodM.A. Malik...
    P.364-371页
    查看更多>>摘要：Cadmium selenide nanoparticles coated with zinc sulphide CdSe/ZnS were prepared using dual source method. The composites were fabricated by stabilizing chemically synthesized semiconductor CdSe/ZnS into Laurylmethacrylate (LMA) and ethyleneglycol dimethacrylate (EGDMA) matrices in the presence of tri-n-octylphosphine (TOP). CdSe/ZnS were dispersed in toluene as a compatible medium for the polymerization and cross-linking of poly Laurylmethacrylate (LMA) networks. Transparent, fluorescent and flexible nano composites (NCs) materials resulted. The nano size particles and polymer composites were characterized by XRD, TG-DTA, IR, TEM and SEM.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd