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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

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

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

卤代烃的Peng-Robinson状态方程的密度修正

林鸿 , 段远源

工程热物理学报

利用密度平移的方法对Peng-Robinson状态方程计算的液相密度进行了修正,给出了其描述平移量的关联式.对22种卤代烃纯物质的计算结果表明,修正后的PR方程能够很好地计算液相密度,并且能很好地再现纯物质的临界压缩因子,计算精度可以满足工程应用的需要.

关键词: PR状态方程 , 密度漂移 , 卤代烃 , 临界压缩因子

Mechanism of Metal Transfer in DE-GMAW

Kehai Li

材料科学技术(英文)

Modification of conventional gas metal arc welding (GMAW) process is of great potential to achieve high productivity with low cost and strong usability. Double-Electrode GMAW (DE-GMAW) is such a modified arc welding process which is formed by adding a bypass torch (gas tungsten arc welding torch) to a conventional GMAW system. The mechanism of metal transfer in DE-GMAW was proposed and verified in this paper. Experiments show that the critical current is decreased so that spray transfer can be obtained at a lower current level in DE-GMAW. Analysis of this significant change in metal transfer phenomena is conducted, and explanation is given out. It is found that the bypass arc in DE-GMAW lifts the anode point on the droplets such that the electromagnetic force becomes larger and squeezes the droplets so that spray transfer can take
place under welding current lower than that in conventional GMAW.

关键词: Metal transfer , null , null

Properties of ZnO : Al films on polyester produced by de magnetron reactive sputtering

Materials Letters

High preferred (002) orientation Al-doped ZnO (ZAO) films have been prepared by de magnetron reactive sputtering of an alloy target (98.5 wt.% Zn-1.5 wt.% Al) onto polyester substrates. The structural, mechanical, electrical and optical properties were investigated. The ZAO film has a sheet resistance of as low as 47.5 Omega/square and an average visible transmittance of about 70%. An average IR reflectance of about 70% in the region of 2.5-25 mum also has been obtained. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词: Al-doped ZnO (ZAO);polyester;mechanical;IR reflectance;thin-films;optical-properties;oxide-films;electrical-properties;rf;temperature;orientation;parameters;deposition;substrate

Formation of Al-doped ZnO films by de magnetron reactive sputtering

Materials Letters

Highly preferred (002) orientation transparent conductive Al-doped ZnO (ZAO) films were successfully prepared by de magnetron reactive sputtering from a Zn target mixed with Al of 2.0 wt.%. The film has a resistivity of 4.80 X 10(-4) n cm and a visible transmittance of as high as 90%. XPS analysis indicates Al-enrichment on the film surface. The asymmetry of Al 2p(3/2) XPS peak is resolved into two components: one centering at 72.14 eV attributed to metallic Al and the other having a binding energy of 74.17 eV due to oxidized Al. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词: Al-doped;ZnO;XPS;Al-enrichment;oxide thin-films;optical-properties;electrical-properties;rf;dc;transparent;deposition

DE-GMAW高速电弧焊工艺机理的研究

武传松 , 张明贤 , 李克海 , 张裕明

金属学报 doi:10.3321/j.issn:0412-1961.2007.06.021

通过大量的工艺实验,找出了DE-GMAW双焊枪组合的匹配参数,测试了焊接电流波形,拍摄了熔滴过渡图像,并获得了无成型缺陷的焊缝照片.基于实验结果解释了高速焊接工艺的机理.建立了适用于DE-GMAW焊接工艺的有限元模型,并对该工艺条件下的温度场、应力-应变场进行了数值模拟.结果表明:计算出的DE-GMAW焊缝横断面形状尺寸与实验结果吻合良好;在通过焊丝的总电流相同时,DE-GMAW焊接时焊缝尺寸、热影响区宽度、应力、应变及变形均小于常规GMAW焊时的结果.这为DE-GMAW焊接工艺参数优化提供了基础数据.

关键词: 高速电弧焊接 , 工艺机理 , DE-GMAW , 有限元分析

Mechanism of Embrittlement and De-Embrittlement for 225Cr-1Mo Steel

ZHANG Xi-liang , ZHOU Chang-yu

钢铁研究学报(英文版)

The constant embrittlement curve for constant segregation concentration on grain boundary of impurity element P and relationship between equilibrium grain boundary segregation concentration and operation time for 225Cr-1Mo steel were derived based on the theory of equilibrium grain boundary segregation. The mechanism of step-cooling test and mechanism of de-embrittlement for 225Cr-1Mo steel were explained. The segregation rate will increase but equilibrium grain boundary segregation concentration of impurity element P will decrease as temperature increases in the range of temper embrittlement temperature. There is one critical temperature of embrittlement corresponding to each embrittlement degree. When the further heat treating temperature is higher than critical temperature, the heat treating will become a de-embrittlement process; otherwise, it will be an embrittlement process. The critical temperature of embrittlement will shift to the direction of low temperature as further embrittlement. As a result, some stages of step-cooling test would change into a de-embrittlement process. The grain boundary desegregation function of impurity element P was deduced based on the theory of element diffusion, and the theoretical calculation and experimental results show that the further embrittlement or de-embrittlement mechanism can be interpreted qualitatively and quantitatively by combining the theory of equilibrium grain boundary segregation with constant embrittlement curve.

关键词: step-cooling test , critical embrittlement temperature , embrittlement mechanism , grain boundary desegregation

DE-GMAW高速电弧焊工艺机理的研究

武传松 , 张明贤

金属学报

根据当前制造业对高效、优质、低耗焊接技术的迫切要求,研发出低成本的高速电弧焊接新工艺DE-GMAW。该工艺在常规GMAW焊接设备的基础上,通过附加GTAW焊枪构成旁路电弧,分流了一部分通过焊丝的焊接电流,在施加于焊丝的电流较大的情况下(保证了熔敷率),减小了作用于母材的热输入,解决了高速焊接面临的矛盾,实现了高速电弧焊接。建立了适用于DE-GMAW焊接工艺的有限元模型,并对该工艺条件下的温度场和应力变形进行了数值模拟。结果表明:计算出的DE-GMAW焊缝横断面形状尺寸与实验结果吻合良好;在通过焊丝的总电流相同时,DE-GMAW焊接时焊缝尺寸、热影响区宽度、应力、应变及变形均小于常规GMAW焊时的结果。这为DE-GMAW焊接工艺参数优化提供了基础数据。

关键词: 高速电弧焊接 , process mechanism , DE-GMAW , finite-element analysis

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