Advances in titanium metal injection molding

The approaches to production of titanium powder injection molded parts are reviewed. Historically, oxygen levels have been too high for structural use (particularly with the Ti-6Al-4V alloy). However, recent advances in starting powders, binders and sintering facilities now allow oxygen levels in the Ti-6Al-4V alloy to be controlled to about 0.2 wt.% oxygen. This should result in significant expansion of the titanium PIM market place into aerospace, automobiles, surgical instruments, dentistry, communication devices (such as computers and cell phones), knives and guns. __________ Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 5–6 (455), pp. 118–125, 2007.     

A method for evaluating the mechanical performance of thin-walled titanium tubes

A method which was developed to compare the stress–strain properties of three types of thin-walled, commercially pure titanium tubes is presented. The tubes were of types intended for use in large heat-exchanger applications and were to be subjected to significant plastic deformation during subsequent assembly processes. It had been anticipated that small differences in chemical composition and tube-drawing treatment would produce quite different characteristics. It is known that the properties of titanium can exhibit considerable degrees of anisotropy, especially for wrought products; although axial properties of the materials could be evaluated using standard test equipment and procedures, a novel testing system had to be designed to allow the circumferential properties to be assessed. Significant differences between tube types were observed and anisotropic material behaviour was apparent.     

Tribology of nitriding layer, TiN coatings and their complex on AISI D2 steel

The sliding wear and impact wear resistances of D2 steel with nitriding layer, PVD titanium nitride coating and their duplex treatment were investigated. The experimental results suggest that the duplex treatment has the best sliding and impact wear resistances under experimental conditions. And the wear resistance of PVD titanium nitride is better than that of nitriding. The impact wear resistance and wear mechanism of all three surface layers remain unchanged under impact load of 0.2 J or 1 J. All samples end with the same symptom of flaking.     

海绵钛产品的现状及市场发展前景

论述了海绵钛产品的国内外生产研究现状、应用、市场前景及世界各国的发展情况。综观国内外情况，指出我国钛工业市场前景广阔，有很大的发展潜力，海绵钛工业需要进一步扩大规模，钛材加工业需要进一步状大。     

Ti/AlN陶瓷界面反应的热力学研究

对AlN陶瓷在室温和超高真空条件下蒸镀金属钛过程的界面反应进行了热力学研究，并用X光电子能谱（XPS）进行了验证，表明在金属钛沉积以前AlN陶瓷在空气中表面部分被氧化，当样品沉积了金属钛后，刚沉积上的钛是氧化状态，随着钛沉积厚度的增加，表面TiN和Al2O3的成分都增加。     

ZT3钛合金标准物质均匀性的检验

本文采用方差分析法和平均值一致性检验法来检验钛合金标准物质的均匀性,通过铝和硅两个元素的计算,证明该标准物质均匀度良好,数理统计在分析化学中逐步在应用,这将为今后标准物质的研制开辟新的途径。     

海绵城市建设的技术装备应用综述

结合某区域海绵城市建设,从源头减排、过程控制、系统治理3个方面重点介绍了透水铺装、CSO调蓄池、一体化水处理设备等项目各阶段涉及的主要技术装备。同时,归纳总结了各阶段其他技术装备的特点及适用条件,指出海绵城市建设技术装备体系将向预制化、集成化和运程简易化方向发展。     

Measurement of the heat of fusion of titanium and a titanium alloy (90Ti-6Al-4V) by a microsecond-resolution transient technique

A microsecond-resolution pulse heating technique was used for the measurement of the heat of fusion of titanium and a titanium alloy (90Ti-6Al-4V). The method is based on rapid (50- to 100-s) resistive self-heating of the specimen by a high-current pulse from a capacitor discharge system and measuring, as functions of time, current through the specimen, voltage across the specimen, and radiance of the specimen. Melting of the specimen is manifested by a plateau in the measured radiance. The time integral of the net power absorbed by the specimen during melting yields the heat of fusion. The values obtained for heat of fusion were 272 J · g^–1 (13.0 kJ · mol^–1) for titanium and 286 J · g^–1 for the alloy 90Ti-6Al-4V, with an estimated maximum uncertainty of ±6% in each value.Paper presented at the Second Workshop on Subsecond Thermophysics, September 20–21, 1990, Torino, Italy.     

Influence of silicon on the oxidation of titanium between 550 and 700°C

The oxidation behavior of Ti-Si alloys (0.25, 0.5, and 1 Wt. % Si) was investigated between 550 and 700°C; in oxygen by continuous thermogravimetry for a maximum duration of about 500 hr and, in air by daily weighing for durations from a few hundred to several thousand hours. The kinetics results revealed that the presence of silicon leads to a decrease in oxidation rate which is more evident when the temperature is raised and the silicon content is increased. Morphological and structural examinations revealed that silicon modifies the internal architecture of oxide layers when compared with unalloyed titanium; in particular, reduced porosity in the layers is observed. Analysis showed that silicon is uniformly distributed in the oxide layer. However, while part of the silicon is in solid solution in the rutile, some is also precipitated as small crystals ( <1 m at 850°C) of SiO₂, of cristobalite structure. The adherence of oxide layers to the metal substrate was measured after cooling of samples; the addition of silicon has been observed to modify, in a manner dependent on its content, the adherence of oxide layers.     

钛合金固态相变的研究进展

综述了近年来国内外学者在钛合金固态相变理论和实验研究方面的进展情况，介绍了几种钛合金固态相变的研究实验方法，并对钛合金中马氏体、硼、亚稳脚分解等相变动力学、晶体学以及组织的演变、形核生长等进行了总结和归纳。