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A Hybrid Low Temperature Surface Alloying Process for Austenitic Stainless Steels

材料热处理学报 2004年第5期25卷 307-310页

作者： Y.Sun schoolofmaterialsengineering NanyangTechnologicalUniversitySingapore639798

This paper describes a novel, hybrid process developed to engineer the surfaces of austenitic stainless steels at temperatures below 450°C for the improvement in wear and corrosion resistance. The process is carried out in the plasma of a glow discharge containing both nitrogen and carbon reactive species, and facilitates the incorporation of both nitrogen and carbon into the austenite surface to form a dual-layer structure comprising a nitrogen-rich layer on top of a carbon-rich layer. Both layers can be precipitation-free at sufficiently low processing temperatures, and contain nitrogen and carbon respectively in supersaturated fee austenite solid solutions. The resultant hybrid structure offers several advantages over the conventional low temperature nitriding and the newly developed carburizing processes in terms of mechanical and chemical properties, including higher surface hardness, a hardness gradient from the surface towards the layer-core interface, uniform layer thickness, and much enhanced corrosion resistance. This paper discusses the main features of this hybrid process and the various structural and properties characteristics of the resultant engineered surfaces.

关键词：奥氏体不锈钢表面铸合等离子体渗氮等离子体渗碳磨损腐蚀

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Aligned ZnO Nanofibre Array Prepared by Vapour Transport in Air

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Chinese Physics Letters 2003年第8期20卷 1319-1322页

作者：徐春祥孙小卫陈佰军孙长庆郑明江李穗湘 SchoolofElectricalandElectronicEngineering NanyangTechnologicalUniversityNanyangAvenueSingapore639798 schoolofmaterialsengineering NanyangTechnologicalUniversityNanyangAvenueSingapore639798

An aligned zinc oxide nanofibre array has been fabricated by heating the mixture of ZnO, Ga2O3, and graphite powders in atmosphere. The ZnO nanofibre showed a uniform size of about 150nm in diameter and 50µm in length. The nanofibres grew predominantly along one direction. Both x-ray diffraction (XRD) and Raman shift spectra show that the product is composed of ZnO with the typical hexagonal structure. The good crystallinity of these ZnO nanofibres has been verified by photoluminescence spectra with strong UV emission at 287nm and weak green band emission observed at room temperature. The component of the product was analysed by XRD, Raman shift spectrum, x-ray energy dispersion (EDX) and x-ray photoelectronic energy spectroscopy (XPS). The growth process and the characteristics can be interpreted by vapour-liquid-solid mechanism.

关键词： Zinc oxide

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Ablation of GaN Using a Femtosecond Laser

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Chinese Physics Letters 2002年第11期19卷 1711-1713页

作者：刘伟民袁述等 DepartmentofPhysics FudanUniversityShanghai200433 schoolofmaterialsengineering NanyangTechnologicalUniversityBLKN4NanyangAvenueSingapore6397981

We study the pulsed laser ablation of wurtzite gallium nitride (GaN) films grown on sapphire, using the femtosecond laser beam at a central wavelength of 800nm as the source for the high-speed ablation of GaN films. By measuring the backscattered Raman spectrum of ablated samples, the dependence of the ablation depth on laser fluence with one pulse was obtained. The threshold laser fluence for the ablation of GaN films was determined to be about 0.25J/cm2. Laser ablation depth increases with the increasing laser fluence until the amount of removed material is not further increased. The ablated surface was investigated by an optical surface interference profile meter.

关键词： Ablation GaN Using Femtosecond Laser

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ARTIFICIAL NEURAL NETWORKS BASED GEARS MATERIAL SELECTION HYBRID INTELLIGENT SYSTEM

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Acta Metallurgica Sinica(English Letters) 2003年第6期16卷 543-546页

作者： X.C.Li W.X.Zhu G.Chen D.S.Mei J.Zhang K.M.Chen DepartmentofMaterialsEngineering NanjingUniversityofScienceandTechnologyNanjing210014China SchoolofElectricalandInformationEngineering JiangsuUniversityZhenjiang212013China IronandSteelResearchInstitute PanzhihuaIronandSteelGroupPanzhihua617000China SchoolofMechanicalEngineering JiangsuUniversityZhenjiang212013China schoolofmaterialsengineering JiangsuUniversityZhenjiang212013China

An artificial neural networks(ANNs) based gear material selection hybrid intelligent system is established by analyzing the individual advantages and weakness of expert system (ES) and ANNs and the applications in material select of them. The system mainly consists of tow parts: ES and ANNs. By being trained with much data samples, the back propagation (BP) ANN gets the knowledge of gear materials selection, and is able to inference according to user input. The system realizes the complementing of ANNs and ES. Using this system, engineers without materials selection experience can conveniently deal with gear materials selection.

关键词： artificial neural network expert system hybrid intelligent sys-tem gear materials selection

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GLASS （La2O3-B2O3-TiO2） AND CERAMIC（BaNd2Ti5O14） MATRIX COMPOSITES FOR LOW TEMPERATURE CO-FIRED CERAMICS（LTCC）

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陶瓷学报 2005年第2期26卷 87-90页

作者： Seong-JinHwangt Yu-JinKim Hyung-SunKim DepartmentofMaterialsandMetallurgicalEngineering SunchonUniversitySunchon540-742Korea schoolofmaterialsengineering InhaUniversityIncheon402-751Korea

For low temperature co-fired ceramics (LTCC) materials, a glass-ceramic composite consisting of a BaNd2Ti5O14 ceramic, and a lead-free rare earth derived boron glasses (LBT) was tested in this present study. The glass-ceramic composite was evaluated for relative densities, shrinkage and microwave dielectric properties (εr, Qxf0). The sintered body at low temperature demonstrated applicable properties such as high relative density over 85% and various dielectric properties,namely 13-20 for εr, 2000-10000 GHz for Qxf0. The results suggest that the composite has a good potential for using low temperature co-fired ceramic compositions for high-frequency application.

关键词： La2O3-B2O3-TiO2 微波介电特征低温共烧陶瓷介电常数相对密度收缩率

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