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Rare Metals 2010年第1期29卷 86-91页

作者： CHU Ke, JIA Chengchang, LIANG Xuebing, and CHEN Hui school of materials science and engineering, University of science and Technology Beijing, Beijing 100083, china school of materials science and engineering University of Science and Technology Beijing

Two powder mixing processes, mechanical mixing （MM） and mechanical alloying （MA）, were used to prepare mixed Al/diamond powders, which were subsequently consolidated using spark plasma sintering （SPS） to produce bulk Al/diamond composites. The effects of the powder mixing process on the morphologies of the mixed powders, the microstructure and the thermal conductivity of the composites were investigated. The results show that the powder mixing process can significantly affect the microstructure and the thermal conductivity of the composites. Agglomerations of the particles occurred in mixed powders using MM for 30 min, which led to high pore content and weak interfacial bonding in the composites and resulted in low relative density and low thermal conductivity for the composites. Mixed powders of homogeneous distribution of diamond particles could be obtained using MA for 10 min and MM for 2 h. The composite prepared through MA indicated a high relative density but low thermal conductivity due to its defects, such as damaged particles, Fe impurity, and local interfacial debonding, which were mainly introduced in the MA process. In contrast, the composite made by MM for 2 h demonstrated high relative density and an excellent thermal conductivity of 325 W.m^-1.K^-1, owing to its having few defects and strong inter-facial bonding.

关键词： metal matrix composites thermal properties sintering powder mixing

Durability of Alite-calcium Barium Sulphoaluminate Cement

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Journal of Wuhan University of Technology(materials science) 2009年第6期24卷 982-985页

作者：芦令超 school of materials science and engineering University of Jinan

The durability of the cement was mainly studied. Under 1.0 MPa of hydraulic pressure for 8 hours, water could penetrate completely through the sample made by portland cement, but could not penetrate through that by alite-barium sulphoaluminate cement. Under the condition of freezing and thawing cycle, the loss ratio of compressive strength of the cement was only about 17.3% at curing 28 d ages, but the loss of portland cement was as high as 29.5%. Alite-calcium barium sulphoaluminate cement also has an excellent resistance to sulfate attack. The coefficients of resistance to sulfate attack of the cement exceeded 1.0. Meanwhile, the composition and microstructure of the hardened paste of alite-calcium barium sulphoaluminate cement were analyzed by XRD and SEM.

关键词： durability cement alite calcium barium sulphoaluminate

Interfacial Microstructure between WC-Based Cermet and Cu Alloy

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Journal of materials science & Technology 2004年第6期20卷 731-734页

作者： Xinhong WANG, Zengda ZOU, Sili SONG and Shiyao QUschool of materials science and engineering, Shandong University, jinan 250061, china Sch. of Mat. Sci. and Eng. Shandong Univ. Jinan 250061 China

A WC-TiC-Co/CuZnNi composite layer was produced on 1045 steel substrate by means of inside-furnace brazing technique. The microstructure, phase constituent and interfacial diffusion behavior between cermet and CuZnNi alloy were investigated by means of scanning electron microscopy (SEM), transmission electron microscope (TEM), electron probe microanalyzer (EPMA) and X-ray diffraction. The results showed that microstructure of matrix was α and β phases. Cermet particies were surrounded by the α+β phases in the composite layer and their sizes were almost similar to those in original state. The interfacial zone was formed by the mutual diffusion of elements under the condition of high temperature. The interface consists of WC, TiC, CuZn, and CuNi phases, and there are no microcracks and inclusions near the interface.

关键词： Cu-base alloy WC-based cermet Interface behavior Microstructure

Predicting Equation for Adjusting Glass Temperature of Binder Used for P/M Warm Compaction Processing

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International Journal of Minerals,Metallurgy and materials 1998年第1期12卷 39-40页

作者： Shiju Guo Tao Lin Mingyi Li (materials science and engineering school, University of science and Technology Beijing, Beijing 100083, china) materials science and engineering school University of Science and Technology Beijing Beijing 100083 China

Based on considering both negative effect of compacting pressure on glass temperature (Tg) and positiveeffect of plasticizer added into organic binder, a mathematical equation for adjusting Tg of binder used for warmcompaction processing is given. The equation shows that mass fraction of plasticizer need for lowering Tg is function of compacting plessure. The rationality of the equation for warm compaction processing is also discussed.

关键词： warm compaction binder glass temperature

Fabrication of pure copper rods containing continuous columnar crystals by continuous unidirectional solidification technology

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Journal of University of science and Technology Beijing 2004年第3期11卷 240-244页

作者： Hong zhang Jianxin Xie Zidong Wang materials science and engineering school, University of science and Technology Beijing, Beijing 100083, china Mat. Sci. and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Pure copper rods containing continuous columnar crystals were fabricatedusing the downward CUS (Continuous Unidirectional Solidification) equipment. When the technologicalparameters were set as the ranges of mould temperature 1100-1300℃, cooling distance (the distancefrom the exit of the cast mould to the start point of cooling) 10-20 mm, casting speed 0.2-2.5 mm/s,cooling water (20-25℃) volume 1000-1320 L/h, and when these parameters matched reasonably, the CUSprocess was performed stably, and pure copper rods containing continuous columnar crystals withbright and smooth surface were produced. The dendritic arm spacing of the crystals in copper rodsdecreased with increasing the casting speed. The results of the texture by X-ray diffractionanalysis showed that the rods has strong fiber texture.

关键词： copper continuous unidirectional solidification mould temperature castingspeed microstructure texture

Reverse extraction of early-age hydration kinetic equation from observed data of Portland cement

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science china(Technological sciences) 2010年第6期53卷 1540-1553页

作者： WANG Lin1,YANG Bo2,ZHAO XiuYang1,2,CHEN YueHui2 & CHANG Jun3 1 school of Computer science and Technology,Shandong University,jinan 2.0101,china 2 Provincial Key Laboratory for Network-based Intelligent Computing,University of jinan,jinan 250022,china 3 school of Material science and engineering,University of jinan,jinan 250022,china 1. school of Computer science and Technology Shandong University Jinan 250101 China2. Provincial Key Laboratory for Network-based Intelligent Computing University of Jinan Jinan 250022 China3. School of Material Science and Engineering University of Jinan Jinan 250022 China

The early-age hydration of Portland cement paste has an important impact on the formation of microstructure and development of ***,manual derivation of hydration kinetic equation is very difficult because there are multi-phased,multi-sized and interrelated complex chemical and physical reactions during cement *** this paper,early-age hydration kinetic equation is reversely extracted automatically from the observed time series of hydration degree of Portland cement using evolutionary computation method that combines gene expression programming and particle swarm optimization *** order to reduce the computing time,GPUs are used for acceleration in *** have shown that according to the extracted kinetic equation,simulation curve of early-age hydration is in good accordance with the observed experimental ***,this equation still has a good generalization ability even changing chemical composition,particle size and curing conditions.

关键词： Portland cement hydration kinetic equation reverse extraction gene expression programming particle swarm optimization

Fabrication and abrasive wear properties of metal matrix composites reinforced with three-dimensional network structure

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Rare Metals 2006年第6期25卷 671-679页

作者： WANG Shouren GENG Haoran LI Kunshan SONG Bo WANG Yingzi HUI Linhai school of Mechanical engineering Jinan University Jinan 250022 China The Key Laboratory of Liquid Structure and Heredity of materials Shandong University Jinan 250014 China school of materials science Jinan University Jinan 250022 China

Reticulated polyurethane was chosen as the preceramic material for preparing the porous preform using the replication process. The immersing and sintering processes were each performed twice for fabricating a high-porosity and super-strong skeleton. The aluminum magnesium matrix composites reinforced with three-dimensional network structure were prepared using the infiltration technique by pressure assisting and vacuum driving. Light interfacial reactions have played a profitable role in most of the ceramic-metal systems. The metal matrix composites interpenetrated with the ceramic phase have a higher wear resistance than the metal matrix phase. The volume fraction of ceramic reinforcement has a significant effect on the abrasive wear, and the wear rate can be decreased with the increase of the volume fraction of reinforcement.

关键词： metal matrix composites infiltration fficdon and wear three dimensional network structure microstructure

Effects of Surface-Active Elements Sulfur on Flow Patterns of Welding Pool

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Journal of materials science & Technology 2005年第3期21卷 408-414页

作者： Yuzhen ZHAO, Yongping LEI and Yaowu SHI school of materials science and engineering, Beijing University of Technology, Beijing 100022, china school of materials science and engineering Beijing University of Technology Beijing 100022 China

A 3D mathematical model is developed to calculate the temperature and velocity distributions in a moving gas tungsten arc (GTA) welding pool with different sulfur concentrations. It has been shown that, the weld penetration increases sharply with increasing sulfur content. When sulfur content increases beyond 80 × 10-6, the increase in sulfur content does not have an appreciable difference on the welding pool size and shape, and the depth/width remains constant. Sulfur changes the temperature dependence of surface tension coefficient from a negative value to a positive value and causes significant changes on flow patterns. The increase in soluble sulfur content and the decrease at free surface temperature can extend the region of positive surface tension coefficient. As sulfur content exceeds 12.×10-6, the sign of surface tension coefficient is positive. Depending upon the sulfur concentrations, three, one or two vortexes that have different positions, strength and directions may be found in the welding pool. The contrary vortexes can efficiently transfer the thermal energy from the arc, creating a deep welding pool. An optimum range of sulfur content is 20-150×10-6.

关键词： Surface-active elements Sulfur Plow patterns Depth/width

Fabrication of Porous Bulk Metallic Glass

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Journal of materials science & Technology 2005年第6期21卷 788-790页

作者： Keqiang QIU+ and Yinglei REN school of materials science and engineering, Shenyang University of Technology, Shenyang 110023, china school of materials science and engineering Shenyang University of Technology Shenyang 110023 China

An open-cell porous bulk metallic glass （BMG） with a diameter of at least 6 mm was fabricated by using an U-turn quartz tube and infiltration casting around soluble NaCI placeholders. The pore formation and glassy structure were examined by optical microscopy （OM）, scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results show that the pores or cells are connected to each other and the specimen is composed of a mostly glassy phase. This paper provides a suitable method for fabrication of porous BMG and BMG with larger size in diameter.

关键词： Porous bulk metallic glass U-turn quartz tube Infiltration casting

Determination of phase equilibria in the Ni-Ta-Zr system at 12.3 K

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Rare Metals 2003年第3期22卷 160-163页

作者： PAN Ximiao and JIN ZhanpengPhase Diagram and materials Design Center, school of materials science and engineering, Central South University, Changsha 410083, china Phase Diagram and materials Design Center School of Materials Science and Engineering Central South University Changsha 410083

The phase equilibrium relations of the ternary Ni-Ta-Zr system at 12.3 K wereinvestigated by means of diffusion triple and electron probe microanalysis (EPMA) techniques. Twoternary compounds were found and a series of tie lines and tie triangles have been determined. Themaximum solubility of Ta in NiZr_2 is about 13.5% (atom fraction). The corresponding tentativeisothermal section at this temperature was constructed based on current experimental information.

关键词： phase diagram diffusion triple nickel EPMA Ni-Ta-Zr system