检索结果-南通市图书馆

Effect of Al^(3.) on Tobermorite Crystallinity

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 2000年第2期14卷 79-81页

作者： Fengmei Liu Deping Chen Wen Ni Zhenyuan Cao(Resource engineering school, university of {3. and Technology beijing, beijing 100083. china) Univ Sci & Technol beijing Resource Engn Sch Beijing 100083 Peoples R China

The difference between the systems of CaO-SiO2,-H2O and CaO-SiO2-Al(OH)3.-H2O, was studied, especially the effect of Al3.on the crystallinity of tobermorite was focussed. As a result, in the system of CaO-SiO2-H2O, tobermorite formed early, however, withreaction time forward, tobermorite was replaced by xonotlite. So far as CaO-SiO2-Al(OH)3.-H2O was concemed, hydrothermal reactionwas cdried out under the same condition as CaO-SiO2-H2O to study the morphological changes of tobermorite crystals. It was found thatAl3. accelefated the crystal growth of tobermorite to some extent and was in faVor ofplaty crystals. Moreovef, with the Al3. content in-creasing in the starting material, the morphology of tobermorite did not change magnificently, but platy crystals became more and moreeminent. As soon as the Al2O3.content was over 15.6%, synthetic mineral greatly changed in smicthe and haled into hibschite differentfrom 1 .1 nm tobermorite. Obviously, xonotlite was not apt to form in the presence of Al3..

关键词： calcium silicate hydrate xonotlite 1.1 nm tobermorite hibschite

Surface Metallurgy of Nickle Base Superalloy

在线全文

学校读者我要写书评

暂无评论

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 {3., university of science and Technology beijing, beijing 100083. china)(Institute of Surface engineering, Taiyuan university of Technology, Taiyua material science and engineering {3. 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

Two-dimensional simulation on the rolling process of semi-solid 60Si2Mn by finite element method

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and Technology beijing 2002年第4期9卷 273-276页

作者： Renbo Song, Yonglin Kang, Xueping Ren, Hongbo Dong, and Jiwen Wangmaterials science and engineering {3., university of science and Technology beijing, beijing 100083. china Mat. Sci. and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The effect of various process variables on the law of metal flow for semi-solid rolling 60Si2Mn was studied by finite element method. Semi-solid 60Si2Mn can be described as compressible rigid visco-plastic porous material saturated with liquid. In terms of ther-mo-mechanical coupling condition, the distributions of stress, velocity and temperature were studied using software MARC. The simulation results show that the rigid visco-plastic model can accurately describe the semi-solid 60Si2Mn rolling process. The great deformation can achieve completely in view of low flow stress of semi-solid slurry.

关键词： finite-element analysis semi-solid thermo-mechanical coupling compressible rigid visco-plastic model rolling

Anisotropic characteristic in HDDR Nd_(13.Fe_(80)B_7

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and Technology beijing 2003年第3期10卷 26-29页

作者： Jingzhi Han, Aizhi Sun, Yaofu Xiao, Xubo Liu, and Run Wangmaterials science and engineering {3., university of science and Technology beijing, beijing 100083. china materials science and engineering {3. University of Science and Technology Beijing Beijing 100083 China

The function of disproportionation and desorption stages ofhydrogenation-disproportionation-desorption-recombination (HDDR) process in the formation ofmagnetic anisotropy was studied. The results showed that degree of anisotropy (DOA) ofNd_(13.Fe_(80)B_7 induced by appropriate HDDR process is comparable with that ofNd_(13.Fe_(80-x)B_7M_x (M=Co, Zr or Ga), however, the moderate coercive force of Nd_(13.Fe_(80)B_7magnetic powder led to an undesirable (BH)_(max) of 104 kJ/m^3.in bonded magnet. Experimentsdemonstrated that a relatively short disproportionation time, combined with a high desorptiontemperature and slow desorption rate, during HDDR process is beneficial to anisotropy attainment,but HDDR Nd_(13.Fe_(80)B_7 magnetic powder becomes isotropic if the disproportionation time islonger than a certain period. This phenomenon strongly indicated that the origin of anisotropy inNdFeB-type HDDR material is contributed by disproportionation stage. XRD (X-ray Diffraction)analysis and TEM (Transmission Electron Microscope) observation told that no other phase exceptNdH_2, alpha-Fe and Fe_2B has been found in the disproportionation step. The formation of HDDRNd_(13.Fe_(80)B_7 anisotropy might be related to the early lamella disproportionation structure.

关键词： HDDR anisotropy isotropy NdFeB

Numerical simulation of strain localization and damage evolution in large plastic deformation using mixed finite element method

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and Technology beijing 2004年第3期11卷 273-277页

作者： Zhanghua Chen Jiajian Jin Jiumei Xiao Applied science school, university of science and Technology beijing, beijing 100083. china Applied science school University of Science and Technology Beijing Beijing 100083 China

An investigation of computer simulation is presented to analyze the effectsof strain localization and damage evolution in large plastic deformation. The simulation is carriedout by using an elastic-plastic-damage coupling finite element program that is developed based onthe concept of mixed interpolation of displacement/pressure. This program has been incorporated intoa damage mechanics model as well as the corresponding damage criterion. To illustrate theperformance of the proposed approach, a typical strain localization problem has been simulated. Theresults show that the proposed approach is of good capability to capture strain localization andpredict the damage evolution.

关键词： strain localization mixed element truesdell stress rate material damage

Modeling and Optimizing of Deformed Steel Bars Hot Rolling

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 1999年第4期13卷 289-291页

作者： Peng Zhang Yunhui Du Xueping Ren(material science and engineering {3., university’ of science and Technology’ beijing, beijing 100083. material science and engineering {3. University of Science and Technology Beijing Beijing 100083 China

Based on experimental data, a nonlinear model about tensile strength and technical parameters such as Mn and St content, finishing rolling speed and finishing rolling temperature for deformed steel bars in the process of hot rolling was established by using artificial neural networks. The model can be optimized with a genetic algorithm. The optimum rolling parameters were obtained.

关键词： artificial neural networks modeling genetic algorithm, optimizing

Mechanical Properties and Erosive Wear Resistance of Zirconia Toughened Al_2O_3.TiC Ceramics

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 2000年第2期14卷 110-114页

作者： Lihua Xu Fang Lian Yuyan Guo Qiang Zhen Jose Maria Fonte Ferreira Fuming Wang Wenchao Li(material science and engineering {3., university of science and Technology beijing, beijing 100083. china)(Metallurgy {3., university of science and Tech material science and engineering {3. University of Science and Technology Beijing Beijing 100083 China Metallurgy school University of Science and Technology Beijing Beijing 100083 China Department of Ceramic and Glass engineering University of Aveiro 3810-193 Aveiro Portugal

The effect of ZrO2, content on the fracture toughness, flexural strength and Vickers hardness as well as the erosive wear resistan properties of zirconia toughened Al2O3.TiC ceramic composites has been investigated. The results showed that the improvement in fracture toughness and flexure strength of composites with the content of zirconia less than 50% and 10% in mass fraction respectively,is primarily attributed to stress-induced transformation toughening by the analyse of X-ray diffraction. The dependance of erosion wear resistance on the attak angle and the content of ZrO2, panicles of the composites was also revealed. It is found that the erosion rate of the composites has a sharp rise at a attack angle over 65°. This phenomenon is due to a brittle response to the erosion test by microsmictural observation on eroded surface.

关键词： mechanical properties, erosion ceramic composites

Genetic Algorithm for the Thermal Stresses Optimum Design ofFunctionally Gradient material Plate

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 1999年第3期13卷 224-227页

作者： Xiaodan Zhang Zhengbin Tang Changchun Ge(Applied science school, university of science and Technology beijing, beijing 100083. china) Applied science school University of Science and Technology Beijing Beijing 100083 China

Based on the thermal stress distribution for functionally gradient material (FGM) plates, a Genetic Algorithm (GA) method for the thermal stresses optimum design of FGM plate with computer technologies is given. The m... 详细信息

关键词： functionally gradient material (FGM) thermal stress Genetic Algorithm (GA) crossover mutation

Bursting of Morris-Lecar neuronal model with current-feedback control

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2009年第3期52卷 771-781页

作者： DUAN LiXia1, LU QiShao2 & CHENG DaiZhan3.1 College of science, North china university of Technology, {3. 100144, china 2 school of science, beijing university of aeronautics and astronautics, {3. 100191, china 3.Institute of Systems science, Chinese Academy of sciences, {3. 100190, china College of science North China University of Technology Beijing 100144 China school of science Beijing University of Aeronautics and Astronautics Beijing 100191 China Institute of Systems science Chinese Academy of Sciences Beijing 100190 China

The Morris-Lecar (ML) neuronal model with current-feedback control is considered as a typical fast-slow dynamical system to study the combined influences of the reversal potential VCa of Ca2+ and the feedback current I on the generation and transition of different bursting oscillations. Two-parameter bifurcation analysis of the fast subsystem is performed in the parameter (I, VCa)-plane at first. Three important codimension-2 bifurcation points and some codimension-1 bifurcation curves are obtained which enable one to determine the parameter regions for different types of bursting. Next, we further divide the control parameter (V0, VCa)-plane into five different bursting regions, namely, the "fold/fold" bursting region R1, the "fold/Hopf" bursting region R2, the "fold/homoclinic" bursting region R3. the "subHopf/homoclinic" bursting region R4 and the "subHopf/subHopf" bursting region R5, as well as a silence region R6. Codimension-1 and -2 bifurcations are responsible for explanation of transition mechanisms between different types of bursting. The results are instructive for further understanding the dynamical behavior and mechanisms of complex firing activities and information processing in biological nervous systems.

关键词： neuron bursting bifurcation fast-slow dynamics analysis codimension