材料期刊网

放电等离子超快速烧结 SiC-Al2O3纳米复相陶瓷

高濂 , 王宏志 , 洪金生 , 宫本大树 , DIAZ DE LA TORRE Sebastian

无机材料学报 doi:10.3321/j.issn:1000-324X.1999.01.009

本文介绍用非均相沉淀法制备的纳米SiC-Al2O3复合粉体经放电等离子超快速烧结得到晶内型的纳米复相陶瓷,超快速烧结的升温速率为600℃/min,在烧结温度不保温,迅即在3min内冷却至600℃以下.与热压烧结相比,可降低烧结温度200℃以上.力学性能研究结果表明,在1450℃超快速烧结得到的纳米复相陶瓷的抗弯强度高达1000MPa,维氏硬度为 19GPa,断裂韧性也比Al2O3有所提高.TEM像显示纳米SiC颗粒大多分布在Al2O3母体晶粒内,而断裂表面的SEM像表明,穿晶断裂是其主要的断裂模式,这是所制备的纳米复相陶瓷力学性能大幅提高的主要原因.

关键词: 纳米碳化硅复相陶瓷 , 放电等离子烧结 , 超快速烧结

SiC-ZrO2(3Y)-Al2O3纳米复相陶瓷的力学性能和显微结构

高濂 , 王宏志 , 洪金生 , 宫本大树 , DIAZ DE LA TORRE Sebastian

无机材料学报 doi:10.3321/j.issn:1000-324X.1999.05.015

本文介绍用非均相沉淀方法制备的纳米SiC-ZrO2(3Y)-Al2O3复合粉体经放电等离子超快速烧结得到晶内型的纳米复相陶瓷,超快速烧结的升温速率为600℃/min,在烧结温度不保温,迅即在3 min内冷却至600°C以下. 力学性能研究结果表明,在1450℃超快速烧结得到的纳米复相陶瓷的抗弯强度高达1200MPa,断裂韧性K1c为5 MPa1/2. TEM像显示纳米SiC颗粒大多分布在Al2O3母体晶粒内,也有一些纳米SiC颗粒分布在ZrO2晶粒内. 断裂表面的SEM像表明,穿晶断裂是其主要的断裂模式,这是所制备的纳米复相陶瓷力学性能大幅提高的主要原因.

关键词: 纳米复相陶瓷 , 放电等离子烧结 , 力学性能 , 显微结构

放电等离子快速烧结纳米3Y-TZP材料

李蔚 , 高濂 , 郭景坤 , 宫本大树 , DIAZ DE LA TORRE Sebastian

无机材料学报 doi:10.3321/j.issn:1000-324X.1999.06.025

本文采用放电等离子烧结技术(SPS)快速烧结纳米3Y-TZP材料.利用SPS技术快速烧结,可制备出完整、致密的3Y-TZP材料.在烧结温度为1300℃、保温3min条件下,相对密度达98.2%,晶粒仅100～130nm.研究发现:材料的密度随烧结温度的变化趋势与一般快速烧结有明显区别;材料的晶粒随烧结温度的提高而长大,但长大幅度小于其他一些烧结方法所得的3Y-TZP材料.本研究对这些现象进行了理论解释.研究同时表明:通过提高烧结速率制备晶粒<100nm的3Y-TZP材料是很困难的.

关键词: 纳米3Y-TZP , 放电等离子烧结

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

DE-81(3)型碱性锌酸盐镀锌工艺的应用

王朝铭

电镀与涂饰 doi:10.3969/j.issn.1004-227X.2005.04.014

DE-81(3)型碱性镀锌工艺具有单位面积电流密度大、生产效率高,镀液对金属杂质的容忍量大等优点.介绍了该镀锌工艺的生产流程和工艺配方,及其钝化工艺配方;各成分的用量范围及其作用.详细说明了镀液维护的要点.采用DE-81(3)型碱性镀锌工艺大批量处理多品种、尺寸不一、形状各异的零件,经过多年的生产实践和抽样检测结果,镀层外观、附着力、厚度和耐盐雾试验均达到国家标准.

关键词: 锌酸盐镀锌 , 应用