Gum Metal钛合金研究进展

Gum Metal特指一类符合某些特定电子状态参数和成分条件的钛合金,具有很多特异的性能,如室温超塑性、低加工硬化率,经历超过90%的冷旋锻后具有高强度、非线性超弹性、低的杨氏模量,以及Invar和Elinvar性能等.自Gum Metal问世以来,其特异性能的机理和变形机制便一直存在很大的争议.本文结合作者近几年的研...     

Effect of Rare Earth on the Crystallization Behavior of Li₂O-Al₂O₃-SiO₂ Glass-ceramic

X-ray powder diffraction and Fourier transform infrared spectroscopy were applied for characterization of Li2O-Al2O3-SiO2 glass-ceramic powders doped with Eu2O3,Gd2O3 and Er2O3,respectively,in the conditions of different heat-treatment temperatures and with various amounts.The powders were derived from the polyacrylamide gel method.The results show that,the wet gels prepared by polyacrylamide perform a unique crystallization behavior in the process of drying,comparing with some customary preparation such as melt processing.The main crystal phase and crystallization sequence of Li2O-Al2O3-SiO2 micro-powders have no distinct with addition of Eu2O3,Gd2O3 or Er2O3,while the crystallization temperature of the β-spodumene decreased and the amount of the β-spodumene increased.     

聚丙烯酰胺凝胶法制备Li2O-Al2O3-SiO2微晶玻璃超微粉

以丙烯酰胺、N,N′-亚甲基双丙烯酰胺、碳酸锂、硝酸铝和正硅酸乙酯为原料,首次采用聚丙烯酰胺凝胶法成功地制备出多组分氧化物Li2O-Al2O3-SiO2(LAS)微晶玻璃超微粉末。用TG-DTA,IR,XRD,TEM对热处理产物进行了表征。实验表明：热处理温度在800～1000℃时,LAS凝胶粉以六方晶系的β-石英固溶体结构析出;热处理温度在1100℃时,β-石英固溶体开始转变成稳定的四方晶系β-锂辉石固溶体,到1200℃时已经完全转变为β-锂辉石固溶体。900～1100℃热处理后所获得的LAS粉末晶粒大小为30～50 nm。与传统方法相比,聚丙烯酰胺凝胶法是一种在低温下廉价地快速制备多组分氧化物微晶玻璃超微粉末的理想方法。     

Nb含量对Ti-Nb-0.7Ta-2Zr-1.4O合金室温压缩流变行为的影响

研究Ti-xNb-0.7Ta-2Zr-1.4O(x=22.4,22.85,24.5)钛合金的室温压缩流变行为.结果表明:合金的真应力-真应变曲线上塑性变形阶段均表现出应力振动现象,即应变硬化和应变软化交替出现,应力振动是由压缩过程中占主导地位的变形机制发生变化所引起的.随着合金中Nb含量的升高,塑性变形初始阶段的应力平台阶段消失,应变软化阶段缩短,应力软化值减小.这种现象是由于Nb含量的变化改变了合金的塑性变形机制所致.     

帘线／橡胶复合材料疲劳测试方法

利用自建的试验系统,采用单向聚酯帘线／橡胶复合材料模拟汽车子午胎的胎体,研究了疲劳载荷下橡胶复合材料的变形和损伤累积特性,讨论了两徊加载方式对疲劳性能的影响,结果表明：定载荷疲劳测试优于伸长疲劳测试,为评价轮胎的疲劳特性,预报轮胎的疲劳寿命提供了有效手段。     

Li2O-Al2O3-SiO2系微晶玻璃的制备方法和应用现状

综述了Li2O-Al2O3-SiO2系微晶玻璃和微晶玻璃粉的制备方法,介绍了Li2O-Al2O3-SiO2系微晶玻璃在炉灶面板和精密光学仪器零部件的应用概况.     

ZrO2对Li2O-Al2O3-SiO2微粉析晶行为的影响

采用高分子网络凝胶法成功地制备出Li2O-Al2O3-SiO2-ZrO2(LASZ)微晶玻璃粉,探讨了添加不同含量ZrO2对LASZ微晶玻璃的析晶行为和相转变的影响.研究表明:热处理温度在700～1200 ℃时,LASZ微粉先形成六方晶系的β-石英固溶体,随热处理温度的升高,逐渐转变为稳定的四方晶系β-锂辉石固溶体.ZrO2含量增加,降低了β-石英固溶体的结晶温度,延迟了β-石英固溶体向β-锂辉石固溶体的转变.当ZrO2的物质的量分数从0增加到4.0%时,析晶活化能从304.6kJ/mol降低到248.9kJ/mol.所获得的LASZ粉末晶粒大小为20～60 nm,晶粒尺寸随温度的升高而增大,随ZrO2的增加而下降.本实验所制备的LASZ微晶玻璃的热膨胀系数为(4～14)×10-7/℃.     

固溶时效处理对Ti-5.43Al-3.11Mo-1.41V合金显微组织和力学性能的影响

对BT14钛合金(Ti-5.43Al-3.11Mo-1.41V)进行不同温度固溶+时效热处理,研究了固溶温度对合金的显微组织、元素分布和硬度和压缩性能的影响。结果表明,在β相转变温度以下固溶后,随固溶温度上升,初生α相含量不断减少,初生α相和基体相(α′、α″或亚稳β相)中的Al含量均增加,Mo和V含量均下降,显微硬度上升。890、940、990 ℃固溶+540 ℃×6 h时效处理后,基体相分解形成弥散细小的α+β相,起到显著的强化作用,导致显微硬度整体提高,且随着固溶温度的升高,显微硬度和压缩屈服强度提高。     

Bi2Te3基热电材料输运性质优化策略研究进展

随着能源需求的持续增长和不可再生资源的不断耗竭,世界各国高度关注新型能源的开发,同时也致力于提高工业废热的回收率和利用率。热电材料是一种能够实现热能和电能直接转换的固态介质,以其为核心的热电器件不含运动附件且不排放污染物,已在半导体制冷和局部热管理领域实现商业化,例如户外制冷机、车载冷柜、光电芯片和功率激光器的控温装置等。热电制冷非常适于小空间热源的主动冷却,可能成为下一代通讯和信息技术的热管理难题中唯一可行的解决方案。Bi2Te3基化合物作为近室温区兼具稳定理化性质和优异输运性质的热电材料,一直受到学术界和产业界的广泛关注。本文在概述热电材料研究背景和制备方法的基础上,从能带工程、声子散射工程、热变形工艺、结构低维化等方面对热电性能的优化方法进行了归纳,并对未来机遇进行了展望。     

Thermal stability, thermal decomposition and mechanism analysis of cycloaliphatic epoxy/4,4′-dihydroxydiphenylsulfone/aluminum complexes latent resin systems

The thermal stability of latent resin systems, cycloaliphatic epoxy/4,4??-dihydroxydiphenylsulfone/aluminum complexes, was investigated by dynamic differential scanning calorimetry (DSC) analysis. Experiments were conducted under non-isothermal condition in a nitrogen atmosphere at the heating rate of 10, 20, 30 and 40 °C/min, respectively. TG curves showed that, in the temperature range of 25 to 600 °C, the stability of the resin systems could be enhanced by increasing the length of the aliphatic chain in the initiator. Both the Kissinger method and the Ozawa-Flynn-Wall method were employed to calculate activation energies of the decomposition reaction, and the values obtained from the two methods were compared. Moreover, the corresponding reaction mechanism was identified by the Achar differential method and the Coats-Redfern integral method. The experimental results showed that these four methods were reliable and effective to study the kinetics of the thermal decomposition reaction; and the most probable thermal decomposition mechanism of the resin systems we proposed was found to comply with Mampel power law (m=1).