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Effect of the silicon powder content on the properties of Al2O3-SiC-Me composites

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中国科学:技术科学 2010年第4期 460-460页

By means of transient plastic phase process,the Al2O3-SiC-Me composites were produced throungh adding metal aluminium and silicon-powder to Al2O3-SiC *** the condition of the same content of silicon and aluminium mixed-powder,the effect of silicon powder addition on properties of Al2O3-SiC-Me composites was studied by means of XRD and EPMA analyses in the temperature range of 300°C-1600°*** results indicated that the content of metal phase in the sample at 1600°C increases with increasing silicon powder *** the same time,when the temperature is lower than 1100°C,the strength of samples gradually increases with increasing *** when the temperature is higher than 11000°C,the strength of samples gradually decreases with increasing temperature,and this change is very *** results also indicated that at the same sintering temperature,the sample with 6%silicon powder has the maximum strength.

关键词： composites strength ceramic

Extrusion Upsetting Multiple Processing in Sandglass Die

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Rare Metals 2001年第1期20卷 62-65页

作者： Wenlin Lu, Yong Wang, Zezhou Feng, Jintao Hai (beijing Research institute of Mechanical & Electrical technology, beijing 100083, china academy of machinery science and technology, beijing 100044, china) 机械部北京机械所北京 100083 机械部机械科学研究院北京 100044

A new method of getting ultrafine grain size has been investigated, which is called 'Extrusion Upsetting Multiple Processing in Sandglass Die' or 'Sandglass Extrusion' (SE). Since the shape of tested billet can remain unchanged after SE, the billet can be extruded repeatedly in order to get large plastic strain. The ultrafine grain size can be obtained in the billet material due to the large plastic strain and the dynamic recrystallization during SE. The experiments on SE of Zn-5% Al alloy have been done. The SE technology, microstructures, microhardness and superplasticity of tested material after SE have been studied. The experimental results show that the equal-axial ultrafine microstructures can be introduced to the bulk test material during sandglass extrusion. The high strain rate superplasticity can be realized.

关键词： sandglass extrusion ultrafine grain large plastic strain superplasticity Zn-Al alloy

Cleaning of Chromate Manufacture Process

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International Journal of Minerals,Metallurgy and materials 2000年第2期14卷 132-134页

作者： Xing Zou Yi Zhang(Applied science School, University of science and technology beijing, beijing 100083, china)(institute of engineering Chemistry and Metallurgy, Chinese academy of sciences, beijing 100080, china) Applied science School University of Science and Technology Beijing Beijing 100083 China institute of engineering Chemistry and Metallurgy Chinese Academy of Sciences Beijing 100080 China

Sodium chromate solubility is determined in the range of NaOH concentrations from 450 to 810 g/L andsolution temperatUres from 30 to 110℃. The optimized conditions to separate sodium chromate from NaOH inleached solution are resolved. It is first found the method to efficiently separate sbdium chromate from NaOH andsodium altuninate in crude sodium chromate. Bench-scale studies on the separating are performed. Finally, goodseparation results are achieved.

关键词： chromate separation clean process

Special Orientation Relationships Observed at the Early Stages of Recrystallization in Pure AlMn Alloy

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International Journal of Minerals,Metallurgy and materials 1998年第3期12卷 140-146页

作者： Ping Yang(material science and engineering School, University of science and technology beijing, beijing 100083, china)(institute for Metal science and Metal Physics, Aachen University of technology, D-52056, Aachen, Germany) material science and engineering School University of Science and Technology Beijing Beijing 100083 China institute for Metal science and Metal Physics Aachen University of Technology D-52056 Aachen Germany

Electron Back Scattering Diffraction (EBSD) technique in a SEM was used to obtain local orientationalinformation on new grains and their surrounding deformed matrices at the early stages of recrystallization in pureA1-1 .3%Mn alloy. Results show that special orientation relationships including twin-relationship often exist betweennew grains, between new grains and deformed grains or between deformed grains. The occurrence of such specialorientation relationships is attributed to the special deformation behavior in the samples with large initial grain *** formation of recrystallization twins is discussed in a different way to those of traditional ones.

关键词： Orientation relationship recrystallization AlMn, EBSD

The mathematical model of wetting angle of heterogeneous nucleation

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science china(Technological sciences) 2004年第4期47卷 391-397页

作者： HUANG Cheng1, SONG Bo1, MAO Jinghong2 & ZHAO Pei3 1. School of Metallurgical and Ecological engineering, University of science and technology beijing, beijing 100083, china 2. School of material science, University of science and technology beijing, beijing 100083, china 3. Central Iron and Steel Research institute, beijing 100081, china School of Metallurgical and Ecological engineering University of Science and Technology Beijing Beijing China School of material science University of Science and Technology Beijing Beijing China Central Iron and Steel Research institute Beijing China

The heterogeneous nucleation has been analyzed in terms of the thermodynamic theory, and the mathematical model of wetting angle of heterogeneous nucleation has been developed based on the dynamic requirements of hetero- and homogeneous nucleation. With the wetting angel model, the wetting angles of different catalysts in liquid iron have been calculated. The result shows that the wetting angle of most catalysts is smaller than 40, and the value of f() is far less than 1. The wetting angles of TiN, TiC and RE2O3 are smaller, while the wetting angle of MnO is bigger among the ordinary nucleation catalysts. The wetting angles calculated by this model are in agreement with the results of other research work.

关键词： heterogeneous nucleation, mathematical model, wetting angle, undercooling.

Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

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science china(Technological sciences) 2006年第5期49卷 521-536页

作者： CHEN Zhiyong1,2, CAI Hongnian1, ZHANG Xinming2, WANG Fuchi1 & TAN Chengwen1,3 1. School of material science and engineering, beijing institute of technology, beijing 100081, china 2. School of material science and engineering, Central South University, Changsha 410083, china 3. School of material science and engineering, beijing University of Aeronautics and Astronautics, beijing 100083, china School of material science and engineering Beijing Institute of Technology Beijing China School of material science and engineering Central South University Changsha China School of material science and engineering Beijing University of Aeronautics and Astronautics Beijing China

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112 and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.

关键词： twinning slip face-centered cubic crystals axisymmetric co-deformation Bishop-Hill maximum work principle yield strength anisotropy

Electrochemical studies of nickel deposition from aqueous solution in super-gravity field

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science china(Technological sciences) 2007年第1期50卷 39-50页

作者： GUO ZhanCheng1,2, GONG YingPeng2 & LU WeiChang2 1 Metallurgical & Ecological School, University of science and technology, beijing 100083, china 2 institute of Process engineering, Chinese academy of sciences, beijing 100080, china Metallurgical & Ecological School University of Science and Technology Beijing China institute of Process engineering Chinese Academy of Sciences Beijing China

The effect of super-gravity on electrochemical deposition of nickel from aqueous solution was studied. The SEM pictures show that the microstructure of nickel film deposited under the super-gravity condition is finer and more uniform compared with that obtained in normal gravity condition, and the crystal grains diminish with the increase of super-gravity coefficient. The XRD patterns indicate that the arrangement of crystalline grains of nickel film deposited under the super-gravity field is more regular, and the crystalline grain sizes decrease with the increase of super-gravity coefficient. Toughness, tensile stress and hardness of the nickel film are markedly raised with the increase of super-gravity coefficient, and hydrogen content in the nickel film decreases with the increase of super-gravity coefficient. From the polarization curves of hydrogen evolution reaction under the super-gravity condition, a significant reduction of over-potential on electrode was found when current density increased. The process of hydrogen evolution reaction was enhanced under the super-gravity condition. The electro-deposition rate, the microstructure and properties of deposited nickel film under super-gravity condition were still affected by the relative orientation between inertia force and depositing surface. It is favorable to gain the nickel film with better mechanic properties when inertia force orientates vertically towards depositing surface. Keywords super-gravity - electrochemistry - electro-deposition - nickel film Supported by the Notional Natural science Foundation of china (Grant No. 50674011)

关键词： super-gravity electrochemistry electro-deposition nickel film

Modified HDDR Process for Producing Anisotropic NdFeB Powders

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Journal of University of science and technology beijing 2001年第2期8卷 111-114页

作者： Xubo Liu, Yue Ming, Yaofu Xiao, Qi Zeng, Zhengyi Zhang, Run Wang (material science and engineering School, University of science and technology beijing, beijing 100083, china) (beijing institute of Aeronautical materials, beijing 100095, china) material Sci. and engineering School University of Science and Technology Beijing 100083 China

The effect of HDDR (hydrogenation-decomposition-desorption-recombination process) treating conditions on magnetic anisotropy of Nd13FebalCo17B7Ga1Zr0.1 powders has been studied. It is found that increasing recombination temperature is effective for magnetic anisotropy formation, but at the cost of reducing the coercive force. The microstructure analysis (TEM) indicates that the NdFeB recombination nucleation takes place markedly during the transition range from decomposition stage to recombination stage, in which both temperature and H-2 pressure change sharply. In order to create a more stable treatment condition for recombination nucleation, a modified HDDR process is established in which the conventional continuous transition range is divided into several stages. The experimental results have proved that such a process can effectively enhance the remanence of the magnet powders with high certainty, while only cause a little reduction in coercivity.

关键词： HDDR anisotropy NdFeB

Surface Metallurgy of Nickle Base Superalloy

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International Journal of Minerals,Metallurgy and materials 1999年第1期13卷 47-49页

作者： Xu Zhang Zhongmin Yang Jianxin Dong Xishan Xie Yuan Gao Zhong Xu (material science and engineering school, University of science and technology beijing, beijing 100083, china)(institute of Surface engineering, Taiyuan University of technology, Taiyua material science and engineering School University of Science and Technology Beijing Beijing 100083 China institute of Surface engineering Taiyuan University of Technology Taiyuan 030024 China

The Double Glow Plasma Surface Alloying Technique, the Xu-Tee Process, is a new method to produce high quality alloying layer on the surface of less expensive materials. By using thes technique, the surface alloying layer similar to superalloy Inconel 625 has been obtained on the surface of three kinds of melallic materials (low carbon steel, industrial pure iron, stainless steel Cr18Ni9). The results of the composition and microstructure analyzed by Scanning Electron Microscopy (SEM) and X-Ray Uffrachon (XRD) show that the alloying layer consistS of y matrix and several precipitates (Laves intermetallic phase and carbide etc.). The electrochemical corrosion results show that the surface alloying layer formed on the surface of stainless steel and industrial pure iron have better corrosion resistance than that of nickel base alloy inconel 625 and stainless steel Cr18Ni9 in 3.5%NaCl solution. The exper iments indicate that it is an effective way to obtain the gradient surface alloying layer on the surfaces of steels by using Double Glow Plasma Surface Alloying Technique.

关键词： double glow nickel base alloy plasma surface alloying