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Influence of Fe/Ni/Al Additive on the Sintering Behaviors of TiB_2.Cermets

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Journal of wuhan univer{2. of technology(materials Science) 2009年第6期24卷 879-882页

作者：陈华张金咏 state key {2. of advanced technology for materials synthesis and processing Wuhan university of Technology

Fe-Ni-Al mixtures as hot-pressing sintering additive to Titanium diboride （TiB2. were studied. It is found that liquid alloy formed under high temperature hardly has effects on the densification behaviors of TiB2.independent. Fe-Ni-Al additive just works as filler between TiB2.particles and does not change the TiB2.independent sintering behaviors. Pressing mode has a great effect on the liquid flowing between TiB2.particles. Multiple-steps pressing mode will give more time and space for the liquid flowing and improve the relative density of TiB2.Fe-Ni-Al cermet.

关键词： hot-pressing liquid content pressing modes

Fabrication of Ti_2.lC by Spark Plasma Sintering from Elemental Powders and Thermodynamics Analysis of Ti-Al-C System

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Journal of wuhan univer{2. of technology(materials Science) 2007年第2期22卷 325-328页

作者：王苹 state key {2. of advanced technology for materials synthesis and processing Wuhan University of Technology

A ternary-layered carbide Ti2.lC material could be synthesized by spark plasma sintering（SPS） technology using elemental powder mixture of Ti, Al and active carbon. By means of XRD and SEM, phases were identified and microscopically evaluated. The experimental results show that the main phase in the product was fully crystallized Ti2.lC with small particle size when sintered at 12.0℃. The synthesis temperature of SPS was 2.0-400℃ lower than that of hot pressing （HP） or hot isostatic pressing （HIP）. Through thermodynamics calculations, the mechanism of Ti2.lC was studied by calculating changes of Gibbs free energy of reactions.

关键词： Ti2.lC spark plasma sintering elemental powder thermodynamics analysis

Photocatalytic Degradation of Rhodamine B Dye with High Purity Anatase Nano-TiO_2.Synthesized by a Hydrothermal Method

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Journal of wuhan univer{2. of technology(materials Science) 2011年第4期26卷 600-605页

作者：史晓亮 School of Mechanical and Electronic Engineering Wuhan University of Technology state key {2. of advanced technology for materials synthesis & processing Wuhan University of Technology

High purity anatase nano-TiO2.powders with high photocatalytic activity were prepared by a hydrothermal synthesis method. X-ray diffraction （XRD）, field emission transmission electron microscopy （FETEM）, ultraviolet-visible （UV-Vis） light absorption spectrum and photoluminescence （PL） spectrum were adopted to characterize the catalyst. Effects of temperature, time and sol concentration of hydrothermal synthesis on particle size and phases were investigated. Photocatalytic activities in the degradation of Rhodamine B Dye were studied. The experimental results indicated that photocatalytic activity of the nano-TiO2.powers was much higher than that of P2. （Degussa）.

关键词： TiO2 hydrothermal synthesis photocatalytic activity high purity anatase

Microstructure and Properties of W-15Cu Alloys Prepared by Mechanical Alloying and Spark Plasma Sintering Process

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Journal of wuhan univer{2. of technology(materials Science) 2008年第3期23卷 399-402页

作者：章桥新 School of Mechanical and Electronic Engineering Wuhan University of Technology state key {2. of advanced technology for materials synthesis&processing Wuhan University of TechnologyWuhan 430070China

W-15Cu composite powders prepared by mechanical alloying （MA） of raw powders were consolidated by spark plasma sintering （SPS） process at temperature ranged 1 2.0-1 300 ℃ for 10 min and under a pressure of 30 MPa. By using high energy milling, particles containing very fine tungsten grains embedded in copper, called composite particles, could be produced. The W grains were homogeneously dispersed in copper phase, which was very important to obtain W-Cu alloy with high mechanical properties, fine and homogeneous microstructure. The microstructure and properties of W-15Cu alloys prepared by SPS processes at different temperature were researched. The results show that W-15Cu alloys consolidated by SPS can reach 99.6 % relative density, and transverse rupture strength （TRS） is 1 400.9 MPa, Rockwell C hardness （HRC） is 45.2. the thermal conductivity is 196 W/m-K at room temperature, the average grain size is less than 2.μm, and W-15Cu alloy with excellent properties, homogeneous and fine microstructure is obtained.

关键词： W-15Cu mechanical alloying spark plasma sintering (SPS)

Fractal Analysis of Gas Diffusion Layer in PEM Fuel Cells

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Journal of wuhan univer{2. of technology(materials Science) 2006年第1期21卷 22-25页

作者：石英肖金生 state key {2. of advanced technology for materials synthesis and processing Wuhan University of Technology Wuhan 430070ChinaSchool of Automation Wuhan University of Technology Wuhan 430070 China state key {2. of advanced technology for materials synthesis and processing Wuhan University of Technology Wuhan 430070ChinaSchool of Automotive EngineeringWuhan University of Technology Wuhan 430070China

The aim of this study is to show how fractal analysis can be effectively used to characterize the texture of porous solids. The materials under study were carbon papers, the backing material of the gas diffusion layer （GDL） in Proton Exchange Membrane Fuel Cell （PEMFC）. The fractal dimensions were calculated by analyzing data from mercury porosimetry. The polytotrafluoroethylene （PTFE） treated carbon paper shows a significantly high fractal dimension value than pare sample, and the high fractal dimension signifies that the physical complexity of the pore surface is enhanced. The fractal dimension can be used as a valid parameter to monitor the textural evolution of the samples as the treatment progresses, as this behaves in a similar way to other textural parameters. The use of fractal analysis in conjunction with the results of classical characterization methods leads to a better understanding of textural modificatious in the processing of materials.

关键词： PEMFC gas diffusion layer fractal dimension mewury porosimetry

Facile synthesis of Uniform Hollow Hematite Sub-micro Spheres with Controllable Shell Thickness

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Journal of wuhan univer{2. of technology(materials Science) 2010年第1期25卷 32-38页

作者：闫共芹官建国 state key Lab of {2. technology for materials synthesis and processing Wuhan University of Technology

A simple method was developed to prepare the uniform hematite hollow submicro-spheres with controllable structure and different diameter based on monodisperse poly（styrene-co-acrylic acid） [P（St-co-AA）] particles. The structure and formation mechanism of the hollow spheres were investigated in detail. The control mechanism of shell thickness was also discussed. The results indicated that the shell thickness and coarseness of the synthesized core-shell hematite hollow spheres could be tuned simply by the surface carboxyl content of the P（St-co-AA） particles. This method provided a new approach for the structure control in the preparation of hollow spheres. A Brunauer-Emmett-Teller （BET） test shows that the prepared hollow spheres have large surface areas which were decreased along with the increase of the diameter. The magnetic properties of the as-obtained hematite hollow spheres were investigated. The result showed that the coercivity and saturated magnetization were increased along with the increase of the shell thickness, and the remanent magnetization was increased along with the decrease of the diameter.

关键词： hollow spheres hematite shell thickness BET special surface area magnetization properties

Preparation of TiAl/Ti_2.lC Composites with Ti/Al/C Powders by In-situ Hot Pressing

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Journal of wuhan univer{2. of technology(materials Science) 2006年第2期21卷 14-16页

作者：梅炳初严明 state key Lab of {2. technology for materials synthesis and processing Wuhan University of Technology Wuhan 430070 China

TiAl/Ti2.lC composites were prepared by in-situ hot pressing of TilAl/C powders mixtures and sintered at different temperatures were investigated by X- ray diffraction （ XRD ） of samples. The reaction procedure of Ti-Al-C system could be divided into three stnges. Below 900℃ , Ti reacts with Al to form TiAl intermetallics ; above 900 ℃ , C reacts with remain Ti to form TiC triggered by the exothermal reaction of Ti and Al ; TiAl reacts with TiC to produce dense TiAl/Ti2.lC *** the holding stage, ternary Ti2.lC develops to layered polycrystal and composites pyknosis in the meanwhile. The mechanism of synthesis and microstructure was especially discussed.

关键词： Ti-Al-C system TiAl/Ti2.lC composites in-situ hot pressing microstructure

Novel Magnetorheological Suspensions Based on Co-Phthalocyanine/Fe Nanocomposite Particles

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Journal of materials Science & technology 2001年第5期17卷 511-516页

作者： Rongzhou GONG and Zekun FENG Dept. of Electronic Science and technology, Huazhong univer{2. of Science and technology, wuhan 430074, china Jianguo GUAN and Runzhang YUAN state key laboratory of advanced technology for materials {12. and processing, wuhan Univ. of Technol. Wuhan 430070 China

A novel magnetorheological (MR) suspension was based on methyl silicone oil and cobalt-phthalocyanine (Co-Pc)/Fe nanocomposite particles, which were synthesized by thermally decomposing liquid carbonyl Fe in the solution of Co-Pc in N, N-dimethyl formamide. The nanocomposite particles were fully characterized by XRD, SEM and HREM, and the thermal, magnetic and MR properties of nanocomposite particles were measured. Such factors as weight percent of particles (w), magnetic field strength (H), temperature (T) and shear rate (gamma) etc influencing on MR properties were investigated. The results indicated that Co-Pc/Fe nanocomposite with density of 3.66 g/cm(3) was almost micro-sized regular spheroids consisting of tens of Co-Pc coated alpha -Fe nanoparticles in inner and Co-Pc layers on surface of the spheroids. They showed good characteristics of anti-oxidation and soft magnetic. Increment of w increased field-induced shear stress (Delta tau) and zero-field viscosity (eta (0)) of MR suspensions monotonously, and improved anti-settlement stability, but eta (0) increased more markedly than Delta tau with increasing w. Delta tau was basically independent on T and gamma while increased obviously with increasing H. With increasing T, response time of the MR suspension to external magnetic field seemed to decrease. As a result, MR suspensions with satisfactory stability and rapid, completely reversible and significant MR effect can be obtained from Co-Pc/Fe nanocomposite particles.

关键词： Fe Co Novel Magnetorheological Suspensions Based on Co-Phthalocyanine/Fe Nanocomposite Particles

Dominant point detecting based non-uniform B-spline approximation for grain contour

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Science china(Technological Sciences) 2007年第1期50卷 90-96页

作者： ZHAO XiuYang1, YIN YanSheng1,2 & YANG Bo3 1 Shandong key laboratory of Engineering Ceramics, Shandong university, Jinan 250061, china 2 School of materials, Ocean university of china, Qingdao 266003, china 3 state key laboratory of advanced technology for materials synthesis and processing, wuhan university of Science and technology, wuhan 430070, china Shandong key laboratory of Engineering Ceramics Shandong University Jinan China School of materials Ocean University of China Qingdao China state key {2. of advanced technology for materials synthesis and processing Wuhan University of Science and Technology Wuhan China

Three-dimension reconstruction from serial sections has been used in the last decade to obtain information concerning three-dimensional microstructural ge-ometry. One of the crucial steps of three-dimension reconstruction is getting compact and fairing grain contours. Based on the achievement of closed raw con-tours of ceramic composite grains by using wavelet and level set, an adaptive method is adopted for the polygonal approximation of the digitized raw contours. Instead of setting a fixed length of support region in advance, the novel method computes the suitable length of support region for each point to find the best es-timated curvature. The dominant points are identified as the points with local maximum estimated curvatures. Periodic closed B-spline approximation is used to find the most compact B-spline grain boundary contours within the given tolerance. A flexible distance selection approach is adopted to obtain the common knot vector of serial contours consisting of less knots that contain enough degrees of freedom to guarantee the existence of a B-spline curve interpolating each contour. Finally, a B-spline surface interpolating the serial contours is generated via B-spline surface skinning.

关键词： composite B-spline dominant points control points grain contour