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Effect of applying a direct current on wettability of liquid Sn-Pb/solid Cu

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Chinese Science Bulletin 1997年第22期42卷 1928-1932页

作者： Wang, WM Bian, XF Chang, FL Qin, JY Ye, YF Shandong univ technol Coll Mat Sci & Technol Jinan 250061 Peoples R China

THE phenomena of wetting on strengthening phases by liquid matrix metals is significant inmanufacturing metal matrix composites. Many methods have been proposed for improving thewettability of liquid metals on solids, which include physical methods and chemical *** direct current (DC) is one of the physical methods. It has advantages in keeping

关键词： Sn-Pb alloy sessile drop method wettability.

Microstructure and Mechanical Properties of TiB_2/(Ni+Mo) Composites Fabricated by Hot Pressing

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Journal of Materials Science & technology 2000年第6期16卷 634-636页

作者： Jinyong ZHANG , Zhengyi FU Wuhan univ. of technol. Wuhan 430070 China

The fabrication of TiB2 ceramics with high performance at a relatively low temperature requires a second phase to assist the densification and control the microstructure. Moreover the interface characteristics of composites must also be considered. Nickel was chosen as a good metallic-bearing additive in this study. In order to optimize the interface, Mo was added. The results show that Mo can affect the interreaction between TiB2 and Ni, and metallic liquid plays an important role in limiting the TiB2 grain growth in sintering.

关键词： NiMo Composites Fabricated by Hot Pressing Microstructure and Mechanical Properties of TiB2 Ni+Mo TiB

Effects of Solution Temperature on Tensile Properties ofSiC_w/2024Al Composite

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Journal of Materials Science & technology 1995年第4期11卷 291-294页

作者： MA, ZY LU, YX LUO, M BI, J ZHANG, YZ NE univ technol SHENYANG 110006PEOPLES R CHINA

The effects of solution (quench) temperature on the properties of SiCW/Al composite have been investigated using tensile tests. The experiments indicate that the solution temperature of the composite fabricated by P/M technique can be raised to 560 degrees C. The tensile strength of the composite is obviously dependent on solution (quench) temperature and the composite solutionized at 540 degrees C exhibits a maximum of tensile strength and elongation-to-failure. These results can be accounted for by the variation of the dislocation density in the composite.

关键词： Metallic matrix composites

Microstructure, Impact Toughness and TEM Analysis in the CGHAZ of HQ130 High Strength Steel

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Journal of Materials Science & technology 1999年第6期15卷 555-558页

作者： Zou, ZD Li, YJ Yin, SK Shandong univ technol Jinan 250061 Peoples R China

Microstructure and impact toughness in the coarse grain heat-affected zone (CGHAZ) of HQ130 high strength steel were studied by using the weld thermo-simulation test. Fracture morphology and fine structure in the CGHAZ were analyzed by means of SEM, TEM and electron diffraction. Experimental results indicated that the impact toughness and hardness in the CGHAZ (T-m = 1350 degrees C) decreased with increasing cooling time (t(8/5)), and fracture morphology changed from dimple fracture into cleavage fracture. The reason for the toughness decrease is the formation of upper bainite. During application, the welding heat input should be strictly limited, to reduce brittleness in the CGHAZ of HQ130 steel.

关键词： Steel

Influence of doped Ag^+ on multifunction characteristics in SrTiO_3 ceramics

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中国有色金属学会会刊：英文版 2000年第1期10卷 69-72页

作者：徐庆陈文袁润章 Wuhan univ technol State Key Lab Adv Technol Mat Synth & Proc Wuhan 430070 Peoples R China Wuhan univ technol Inst Mat Sci & Engn Wuhan 430070 Peoples R China

SrTiO 3 capacitor varistor multifunction ceramics is fabricated by a single sintering process. The research is carried out, mainly aimed at the influence of the doped Ag + on multifunction characteristics in SrTiO 3 ceramics and its mechanism. The results show that the density of grain boundary acceptor state increases effectively due to the fact that Sr 2+ on grain surface is substituted by doped Ag distributing at grain boundary in form of Ag + during the course of oxidizing annealing, which is proposed to be the fundamental reason for understanding the significant difference of both the dielectric properties and varistor properties in SrTiO 3 ceramics samples with various Ag + contents.

关键词： SrTiO 3 ceramics capacitor varistor multifunction Ag + doping

Fabrication of A1/Al_2O_3 Composites and FGM

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Journal of Materials Science & technology 2001年第6期17卷 646-648页

作者： Hong TAO, Chengji DENG, Lianmeng ZHANG and Runzhang YUAN State Key Laboratory of Advanced technology for Materials Synthesis and Processing, Wuhan university of technology, Wuhan 430070, China [Manuscript received November 27 Wuhan univ. of technol. Wuhan 430070 China

Al/Al203 composites of different ratios were hot-press sintered at 575~640℃ under a pressure of 30 MPa for 2 h in a vacuum furnace. It was found that the relative density of the Al/Al203 composites could be increased evidently with the rise of sinter temperature. No reaction occurred between At and Al203 at the sinter temperatures. Under 640℃-30 MPa-2 h experimental condition, Al/Al203 system FGM was successfully fabricated, and its density range changed quasi-continuously from 2.887×103 kg/m3 to 3.1909×103 kg/m3 within the middle 1.0 mm thickness range.

关键词： Fabrication of Al/Al2O3 Composites and FGM Co Al

Influence of size of seed grains and sintering condition on varistor properties of ZnO-Bi_2O_3-TiO_2-Sb_2O_3 ceramics

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中国有色金属学会会刊：英文版 2001年第3期11卷 328-332页

作者：徐庆陈文袁润章 Wuhan univ technol State Key Lab Adv Technol Mat Synth & Proc Wuhan 430070 Peoples R China Wuhan univ technol Inst Mat Sci & Engn Wuhan 430070 Peoples R China

Varistor ceramics of ZnO Bi 2O 3 TiO 2 Sb 2O 3 system have been fabricated by introducing pre fabricated ZnO seed grains with different size distributions respectively. The results show that the varistor properties were significantly influenced by the size of introduced seed grains, and introducing larger seed grains is more advantageous to the modification of microstructure and the improvement of varistor properties. The varistor properties were considerably improved with a moderately increased sintering temperature or time, whereas degraded apparently when the sintering temperature or time was excessively increased. Compared with the sintering time, the sintering temperature plays a more critical role in determining the varistor properties. By introducing pre fabricated ZnO seed grains into the original powders, low voltage ZnO varistor ceramics possessing the desired electrical properties have been produced with a sintering temperature of about 1 210 ℃ and a sintering temperature of 2～2.5 h. [

关键词： ZnO Bi 2O 3 TiO 2 Sb 2O 3 ceramics seed grains sintering temperature sintering time low varistor voltage

An On-line Monitoring System for Hydrogen Distribution in the Metallic Wall Caused by Hydrogen Permeation

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Journal of Materials Science & technology 2001年第3期17卷 346-350页

作者： Gang YU Shenyang university of technology, 110023, China Xueyuan ZHANG and Yuanlong DU State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China E-mail: yugang@*** Shenyang univ. of technol. Shenyang 110023 China

Based on the electrochemical permeation technique and the patent by Du, an intelligent elec-trochemical measurement system for determination of the hydrogen distribution in the wall of hydrogenation reactor has been developed and tested. It consists of a PC computer, a single chip unit, an I/V converter and an electrochemical hydrogen probe. The construction of the electrochemical hydrogen probe is described and the features of the measured system are given. The diffusion coefficient of 2.25CrlMo steel determined with present system was in good agree-ment with the value in the literature. Experimental results of hydrogen concentration in a wall of hydrogen charged testing autoclave made of AISI 321 stainless steel are presented. The present system can intelligently display hydrogen amount-of-substance concentration and mass fraction concentration, hydrogen concentration distribution curves in steels, permeation current density curve. An intelligent detection technique can be provided for predicting the susceptibility to hydrogen-induced cracks owing to hydrogen permeation in the wall of hydrogenation reactor in the field.

关键词： Hydrogen bonds

Upper Bainite Formation Mechanism in Fe-1.36Si-1.01Cr-0.88C Steel

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Journal of Materials Science & technology 1998年第1期14卷 62-64页

作者： Liu, QS Peng, HF Gu, NJ Hebei univ technol Tianjin 300132 Peoples R China

In this paper it is-discussed on the mechanism of upper bainite formation. According to the results obtained in Fe-1.36Si-1.01Cr-0.88C steel, we discovered that the primary upper bainite is formed by subunits arranging along its long axis and steps are formed by subunits growing into different size-along the thickness, the macro-plane of the primary upper bainite plate is the same as the basal plane (shear plane), the formation mechanism of the primary upper bainite plate is the nucleation-growth mechanism of subunits shearing one by one along long axis, controlled by diffusion.

关键词： Steel