Oxidation and embrittlement of Ti-6Al-2Sn-4Zr-2Mo alloy

Ti-6Al-2Sn-4Zr-2Mo titanium alloy is a candidate material for multiwall thermal protection system concepts for advanced space transportation system vehicles. The total oxidation kinetics for this alloy, exposed to laboratory air in the 593–760°C range, were monitored by thermogravimetric analysis. The oxide thickness was measured by microscopy and the substrate contamination was estimated from microhardness measurements. Tensile elongation was determined for selected foil specimens after exposure to simulated space shuttle reentry conditions. The variation of total weight gain with time was found to have two distinct parabolic stages separated by a transient region. This transient was due to a process which involved an increase in the parabolic growth rate constant for the oxide and a simultaneous increase in oxygen solubility at the oxide metal interface. The time dependent increase in oxygen solubility at the interface was from about 7 at. % in stage 1 to about 18 at. % in stage 2. The diffusion coefficient for oxygen in the alloy was determined as a function of temperature using the difference between the total weight gain in stage 1 and the corresponding weight gain due to oxide growth. A model for the total oxidation kinetics, accounting for the two individual components namely oxide growth and solid solution formation, is proposed. The activation energy for the diffusion of oxygen in the alpha-solid solution is shown to be roughly equal to the activation energy for the degradation of tensile elongation for the alloy in the foil gage condition.     

硼钛低合金铸铁的试验研究

本文研究了硼钛对灰铸铁机械性能和耐磨性能的影响。实验发现：灰铸铁中加入适量的硼钛合金后．既可提高耐磨性能，又可提高强度指标。     

Effect of Crystalline Leucite on Porcelain Bonding on Titanium

The effect of elimination of crystalline leucite on porcelain bonding to Ti was studied. The thermal expansion coefficient of low-fusing dental porcelain was decreased by eliminating the crystalline leucite phase. As a result, minimal thermal mismatch and better bonding between Ti and porcelain were obtained.     

Effect of High-Temperature Treatment on n–p Transition in Titania

This paper reports the electrical conductivity and Seebeck coefficient (thermopower) values derived for TiO₂ (rutile) at a temperature range of 923–1353 K and p _O2 of 5 Pa–100 kPa. The effect of high-temperature treatment on the electrical properties of polycrystalline samples is discussed in terms of defect models. Samples sintered at ≥1573 K, as well as the single crystals, show n - to p -type transition, whereas samples sintered at 1473 K remain n -type throughout testing. No effect of grain size on thermopower is observed. These results are consistent with the defect disorder model assuming that titanium vacancies formed during high-temperature treatment (1473–1673 K) are frozen at the measuring temperature (923–1323 K).     

Ti-451合金油瓶的显微组织特征

采用普通金相法研究了451钛合金轻型喷火器油瓶的显微组织特征。研究结果表明：经S-S加工后油瓶壁和瓶底的显微组织相类似，均为晶粒较粗大、具有明显的β晶界、在晶内有片状二次α相析出，是一种过热组织。在距瓶壁表面形成一层白色富氧层，在该层中的显微组织是由块状α相和转变β相组成。     

应重视发展高附加值的有机钛化合物

本文着重介绍了几种有机钛化合物产品的性质和用途等，期望能引起有关部门重视，加强基础研究，积极开发具有高附加值的有机钛化合物新产品。     

Densification of plasma-sprayed titanium and tantalum coatings

Thermal spraying of corrosion- resistant coatings of titanium and tantalum is difficult; dense coatings are not produced, and oxidation of these metals increases coating porosity. In this study, oxidation during plasma spraying was reduced with a shrouding system. Porosity and oxide content also were minimized by optimizing the spraying parameters. After optimization, the coatings still had open porosity and thus were incapable of protecting the substrate material against corrosion in water solutions containing 3 % NaCl. Therefore, posttreatments for improvement of corrosion resistance were studied. Electron beam fusion produced corrosion resistance equal to or better than that of bulk commercial samples of titanium and tantalum.     

二氯二茂钛与取代苯甲醛肟的反应

二氯二茂钛与取代苯甲醛肟钠在二氯甲烷中反应，生成二茂钛单肟衍生物Ｃｐ２ＴｉＣｌ（ＯＮ＝ＣＨＡｒ），其中Ａｒ为邻硝基苯基，间硝基苯基，对硝基苯基，邻氯苯基，间氯苯基，３，４－二氯苯基，间甲氧基苯基，对甲氧基苯基，２，４－二甲氧基苯基和３，４－亚甲基二氧苯基。所有这些新化合物在干燥空气中稳定，对潮湿空气敏感。经元素分析外，核磁氢谱表征，确认了其结构。     

Oxidation of commercial purity titanium

The oxidation kinetics of commercial purity Ti-A55 exposed to laboratory air in the 593–760°C temperature range were continuously monitored by thermogravimetric analysis. The oxide thickness was measured by microscopy and the substrate contamination was estimated from microhardness measurements. The microhardness depth profiles were converted to oxygen composition profiles using calibration data. The oxygen diffusion coefficient in alpha-Ti appears to be approximately concentration independent in the 1–10 at. % oxygen range. The combination of an “effective diffusion coefficient” and an “effective solubility” at the oxide-metal interface usefully describes the diffusion process over the entire composition range. A model for the total parabolic oxidation kinetics, accounting for the two individual components, oxide growth and solid solution formation, has been proposed. Diffusion coefficient for oxygen in TiO₂ has been estimated as a function of temperature and is found to be about 50 times the value in alpha-Ti. The metallographically prepared cross-sections of the oxidized specimens revealed a “moving boundary” in the substrate, parallel to the oxide-metal interface. This boundary was associated with a specific oxygen level of 5.0±0.5 at.%. It occurred at a distance from the oxide-metal interface which was correlatable with temperature and time of exposure. The diffusion coefficient corresponding to the composition of this moving boundary is in excellent agreement with the effective diffusion coefficient for the substrate contamination.     

多弧离子镀膜机(буиат-6)性能分析和工艺参数研究

分析研究了多弧离子镀膜机буиат—６的主要性能。在不同工艺参数条件下，于高速钢基体上制备了Ｔｉ膜和ＴｉＮ膜，用扫描电镜观察Ｔｉ膜表面形貌；用能谱仪对Ｔｉ膜上小液滴颗粒成份进行测试分析；用超微负荷硬度计测量了ＴｉＮ膜的显微硬度；用表面刻划仪测试了ＴｉＮ膜与基体的附着力。实验结果表明：选择适当的工艺条件，包括弧流大小，电磁场强度，镀膜时间以及冷阴极离子源辅助沉积，可获得性能优良的ＴｉＮ膜，其显微硬度可达Ｈｖ２５００，附着力为６５Ｎ。