材料期刊网

INFLUENCE OF HEAT TREATMENT ON OXIDATION PROPERTIES OF C／C COMPOSITES FABRICATED BY HIGH PRESSURE IMPREGNATION CARBONIZATION

Q.Chen , H.J.Li , A.J.Li , H.M.Han , K.Z.Li

金属学报(英文版)

Felt base carbon/carbon composites fabricated by super-high pressure impregnation carbonization process (SPIC) were heat treated at high temperature 2773K. The oxidation properties of felt base carbon/carbon composites were investigated at different temperatures (773-1173K), and the microstructures of carbon/carbon composites were studied by SEM and X-ray diffraction. The experimental results showed that the interlaminar distance of (002) plane (d002 ) deceased while the microcrystaUine stack height (Lc) increased. The oxidation rate of felt base carbon/carbon composites was invariable at certain temperatures. The oxidation mechanism of carbon/carbon composites changed remarkably at the oxidation temperature 973K. At the initial oxidation stage of carbon/carbon composites, carbon matrix was oxidized much more rapidly than carbon felt.

关键词: carbon/carbon composites , null , null

HAN液晶盒中开关时间对形变场弛豫过程的影响

李晓吉 , 郑桂丽 , 张志东

液晶与显示 doi:10.3788/YJYXS20132801.0025

在HAN液晶盒撤掉外加电压的过程(即弛豫过程)中,假定电压的开关时间为有限的,把电压处理为时间的指数衰减函数.在这一假定下,对撤掉外加电压后HAN液晶盒中指向矢的分布情况进行研究,得到了对HAN液晶盒的弛豫过程有影响的电压开关时间的范围.

关键词: HAN液晶盒 , 有限开关时间 , 驰豫过程 , 动力学理论

Oxygen reduction mechanism on copper in a 0.5 M H(2)SO(4)

Electrochimica Acta

The mechanism of the oxygen reduction reaction (ORR) in a naturally aerated stagnant 0.5 M H(2)SO(4) Was studied using electrochemical methods. The cathodic polarization curve showed three different regions; electrochernical impedance spectroscopy (EIS) measurement was used accordingly. The EIS data were analyzed, and the mechanism for the ORR was proposed consequently. The three regions include a limiting current density region with the main transfer of 4e(-) controlled by diffusion (-0.50V < E < -0.40V), a combined kinetic-diffusion region (-0.40V

关键词: Oxygen reduction;Hump phenomenon;Chemical redox;Copper;Electrochemical impedance spectroscopy;sulfuric-acid electrolyte;anodic-dissolution;sulfate-solutions;corrosion;behavior;adsorption;chloride;cu(111);alloy;model

Simulations of Coarsening Behavior for M23C6 Carbides in AISI H13 Steel

Xinbin HU , Mei ZHANG , Xiaochun WU , Lin LI

材料科学技术（英文）

Based on the local equilibrium assumption, coarsening behavior of M23C6 carbide at 700℃ in H13 steel was simulated by DICTRA software. The results from the calculations were compared with transmission electron microscopy (TEM) observations. The results show the interfacial energy for M23C6 in H13 steel at 700℃ is thus probably 0.7 J•m-2, which fits the experiments well. The influence of composition and temperature on the coarsening rate was also investigated by simulations. Simulations show a decrease in the coarsening rate when V/Mo ratio is increased, while the coarsening rate increases with increasing temperature.

关键词: DICTRA Simulation , 碳化物粗化 , 界面能 , H13钢

A Novel near Net-Shape Technique for P/M Parts with Large H/D Ratio

Yong LIU , Baiyun HUANG , Kechao ZHOU , Hongwu OUYANG , Yuehui HE

材料科学技术（英文）

In order to overcome the shortcomings of conventional hot pressing, a novel near net-shape technique, called radial hot pressing, for P/M parts with large height-to-diameter (H/D) ratio was introduced. Effects of processing parameters on the microstructures and density of P/M TiAl base alloy valves were studied. Results show that the radial hot pressing is an effective technique for manufacturing valves with a H/D ratio of about 10:1, and the perfect joint interface between the Mo sheet and the parts is helpful for subsequent HIPing.

关键词: Near net-shape technique , null , null

电场诱导纳米结构HAN液晶盒中新型有序重构过程的描述

陈思博 , 王永超 , 周璇 , 张志东

液晶与显示 doi:10.3788/YJYXS20163109.0853

基于 Landau-de Gennes 理论，利用松弛迭代的方法，研究了包含－1/2向错线的混合排列(HAN)液晶盒中，平行于向错线的电场所诱导的结构转变。结果表明，盒厚固定时，电场诱导五种结构转变过程；电场固定时，盒厚变化产生三类结构转变方式。力曲线上的极小值确定了液晶系统发生结构转变的临界盒厚。

关键词: 有序重构 , Landau-de Gennes理论 , -1/2 向错 , 力曲线

1m3/h RO-EDI高纯水设备的研制

刘红斌 , 龚承元 , 苏建勇 , 朱孟府 , 马军 , 张西正

膜科学与技术 doi:10.3969/j.issn.1007-8924.2002.03.014

介绍了工业规模的EDI膜堆和1 m3/h RO-EDI高纯水设备的研制情况,进行了设备的稳定性试验和EDI产水的水质分析,并与离子交换树脂进行了技术经济性能比较.

关键词: 电去离子 , 反渗透 , 制药用水 , 高纯水

Copper corrosion and anodic electrodissolution mechanisms in naturally aerated stagnant 0.5 M H(2)SO(4)

Corrosion Science

Mechanisms of copper corrosion and electrodissolution in naturally aerated, stagnant 0.5 M H(2)SO(4) were investigated by means of electrochemical techniques, compared with deaerated measurements. The role of dissolved oxygen was suggested, and three models were proposed in -0.05 similar to 0.15 V vs. SCE range. Near to corrosion potential, chemical redox between cuprous intermediate and oxygen reduction reaction (ORR) intermediate accelerated copper corrosion, and corrosion rate was controlled by a combined cathodic kinetic-anodic diffusion process. in low and high potential ranges, chemical redox, occurred between cuprous intermediate and oxygen molecule, synergistically accelerated the electrodissolution of copper. (C) 2009 Elsevier Ltd. All rights reserved.

关键词: Copper;Electrochemical impedance spectroscopy (EIS);Corrosion;Electrodissolution;Chemical redox;acidic sulfate-solutions;sulfuric-acid;electrochemical reduction;impedance spectroscopy;oxygen reduction;disk-electrode;reaction;model;dissolution;behavior;iron

磁制冷材料在不同温度下的M-H曲线测量方法及设备的研究

刘金荣 , 黄焦宏 , 金培育 , 李满才 , 成永顺 , 徐来自 , 邱巨峰 , 杨保荣 , 杨文志 , 王贵 , 王正德 , 张泽玉

稀土 doi:10.3969/j.issn.1004-0277.2001.06.011

为了选择合适的磁制冷材料,得到材料的磁热效应,即ΔS-T曲线,必须测出材料在不同温度下的M-H曲线.我们采用脉冲磁场的方式提供测试所需的高磁场,自行研制了符合测试精度要求的M-H曲线测试装置,测试了金属Gd的-50℃～50℃之间的每隔10℃的不同温度下的M-H曲线.

关键词: 磁热效应 , 脉冲磁场 , 磁熵变 , M-H曲线

M2和H13钢离子渗氮-电弧镀TiAlCrN膜复合技术

陈灵 , 曾德长 , 邱万奇 , 董小虹 , 黎炳雄 , 黄拿灿

材料热处理学报

对M2和H13钢进行离子渗氮-多弧离子镀TiAlCrN膜复合表面改性,并采用电子探针、X射线衍射、扫描电镜、纳米压痕和微米划痕仪等手段分析了薄膜的成分、组织结构与力学性能.结果表明,不同衬底对膜的成分及微观结构影响不大.TiAlCrN/M2和TiAlCrN/H13复合膜的膜基结合力都比较高,而TiAlCrN/M2复合膜的综合力学性能优于TiAICrN/H13.

关键词: 离子镀 , 渗氮 , TiAlCrN涂层 , 微观结构 , 硬度