An Oxygen-Permeation Treatment for Hardening Titanium Alloys

In this paper, the characterization of oxygen permeation (OP) in titanium alloy TC11 at high temperature and the influence of oxygen solution layer on performances of substrate were characterized with the help of apparatus, such as TGA,SEM/EDAX, XRD, EPMA, Micro-hardness Tester, Two-body Abrasion Tester, Amsler Wear Test Machine, Potentiostat/Galvanostat Model 273 system. The results showed that there was a little shift in X-ray diffraction peaks of α and β phase during the OPT process as a result of oxygen solution. The OP treatment can significantly increase the surface hardness of titanium alloys and, accordingly, the abrasive wear resistance was improved. Titanium alloys with oxygen solution layer exhibited improved corrosion resistance both in 3.5 % NaCl and in 5 % HCl solution. Oxidation resistance of TC11 with oxygen solution layer at high temperature was also enhanced. The solution and hardening mechanisms were discussed based on the experimental results.     

45钢低温双辉等离子渗铬硬化的研究

常规双辉等离子渗铬温度较高(800℃以上),能耗较大.为此,采用双辉等离子渗金属技术,在560℃下对45钢进行了表面渗铬硬化,制备出了性能良好的表面合金改性层.采用X射线衍射仪及其附带的能谱仪测定了渗层物相及成分,采用金相显微镜考察了渗层组织形貌,并采用显微硬度计检测了渗层硬度.结果表明:渗层组织由沉积层及扩散层组成;渗层表层为2～3 μm的沉积层,含铬量达到48%以上,沉积层致密并与扩散层结合紧密;内有20～25 μm的扩散层,其合铬量呈梯度分布;表面物相由Fe-Cr、Cr7C3、Cr23C6等组成;渗层表面显微硬度达600～700 HV,硬度向内呈梯度分布.     

混合导电体型氧透膜材料的研究

研究了具有氧离子导电性和电子导电性的钴系钙钛矿型复合氧化物混合导电体材料中氧的选择性透过能力,考察了该体系中 A 位低价金属离子置换量、置换金属离子的种类及 B 位置换金属离子的种类对氧的透过率的影响.结果表明:改变钙钛矿型复合氧化物的组成,提高材料中氧空位浓度和氧离子导电率,有利于提高氧离子的扩散速度,即提高氧的透过率和降低氧透过的起始温度.将钙钛矿型复合氧化物混合导电体氧透膜与固体电解质氧透膜进行了比较,前者具有结构简单的优点,有希望成为一种新型高温氧分离膜介质材料.     

A New Aging Treatment Way for Near α High Temperature Titanium Alloys

Two near α titanium alloys,Ti-5.6Al-4.8Sn-2.0Zr-1Mo-0.35Si(1#) and Ti-6.0Al-4.8Sn-2.0Zr-1Mo-0.35Si(2#),were solution-treated in the upper α+β phase fields,and the duplex mixture microstructures consisting of the less volume fraction primary α phase(αp) and the transformed β phase(βt) were obtained.The aging treatments were carried out at 700℃ for 1# alloy and 760℃ for 2# alloy under varied terms,respectively.It guaranteed α2 ordered phase to precipitate only in αp but not in βt for the two alloys.The slower...     

温度对钛合金TB6显微组织和晶粒度的影响

通过对近β钛合金TB6进行不同温度热处理，研究了各温度下其显微组织和晶粒度大小变化。研究结果表明：钛合金TB6的最佳热处理温度为790℃，在此温度下进行热处理，可以获得较好的显微组织形态且β相可以达到95％左右；晶粒度比较均匀且达到等轴状态，晶粒度为4～4．5级。     

船用钛合金高效焊接工艺研究

本试验以板厚为4mm的Ti70和16 mm的TA5两种钛合金为焊接对象,对等离子弧焊(PAW)、激光焊(LW)及激光-MIG复合焊3种高能量密度高效率的钛合金焊接方法进行了初步的工艺探索,得到了性能优良的焊接接头,研究成果丰富了实船建造的钛合金焊接工艺。     

Oxygen Permeation and Stability of Ce0.8Gd0.2O2-δ-PrBaCo2-xFexO5＋δ Dual-phase Composite Membranes

Dual-phase membranes of 60 wt% Ce0.8Gd0.2O2-δ-40 wt% Pr Ba Co2exFexO3 d（0 x 2） were prepared by a combined citrate and ethylene diamine tetraacetic acid（EDTA） complexing method. X-ray diffraction（XRD）results revealed the good chemical compatibility between ion-conducting phase CGO and electron-conducting phases PBC2 xFxO after sintering in air. The Fe ionic dopant had a significant effect on the phase structure stability and oxygen permeability under CO2 atmosphere, which was confirmed by XRD, thermogravimetrye differential scanning calorimetry（TGeD SC）, scanning electron microscopy（SEM） and oxygen permeation experiments. CGOeP BC0.5F1.5O dual-phase membrane demonstrated a stable oxygen permeation flux of2.71x10-7mol cm 2s 1with 50 mol% He/CO2 as the sweep gas at 925 C, and this value was much higher than that of perovskite-type membranes. The rate-limiting step in the oxygen permeation process changed from the bulk diffusion to the surface oxygen exchange when the CGOeP BC0.5F1.5O membrane thickness decreased to 0.8 mm or less. Due to the high oxygen permeation fluxes and the excellent structural stability under CO2 atmosphere, the CGOeP BC0.5F1.5O membrane is a great potential candidate material for separating oxygen from air in the oxy-fuel combustion techniques.     

Determination of Aluminum in Precipitation Hardening Stainless Steel and High Temperature Alloys

A procedure is described for the determination of aluminum in high temperature alloys. Aluminum is selectively precipitated with 8-hydroxyquinoline from an ammoniacal solution of the alloy containing citrate and cyanide as complexing agents. The precipitate is ignited under oxalic acid, the oxides fused, and dissolved in acid. A caustic precipitation is made, an aliquot of the filtrate treated with hydrogen peroxide, and the aluminum precipitated with 8-hydroxyquinoline. The aluminum hydroxyquinolate is filtered on a fritted-glass crucible, dried, and weighed.     

Friction of Alloys at High Temperature

A brief review is given about the friction and wear properties of high temperature alloys. Above a critical temperature, if the oxide becomes ductile, it will flow over the surface and prevent metal-to-metat contact. In order to study the tribology of oxide lubrication. a series of tests were carried out using Cu(ReO4)2 as a lubricant. The effects of time. Surface finish. substrates. load and temperature were investigated. A mechanism of lubrication is proposed in which the surface slip predominates along with mechanical attachment of oxide to the surface.     

Effects of Oxygen on the Microstructure of Ti_(47)Al_(0.7)B Alloys

The effects of oxygen on the microstructure of Ti-47Al-0.7B (at. pct) alloy for as-cast automotive valves were investigated. Six alloys with oxygen content from 0.4 to 1.4 at. pct were prepared by induction melting and centrifugal casting in CaO crucible under protective atmosphere. The microstructures were observed by optical microscopy (OM) and scanning electron microscope (SEM). The results show that the increase of oxygen content led to grain refinement and enhanced the microhardness as well as the α 2 ...     

氢对钛合金的影响

介绍了钛合金的基本性质,分析了钛合金氢脆机理及表现,概括了氢对钛合金裂纹扩展速率和疲劳寿命的影响,总结了氢致裂纹的影响因素。     

Effect of Ni interlayer on strength and microstructure of diffusion-bonded Mo/Cu joints

Mo and Cu were bonded successfully by means of diffusion bonding using a Ni interlayer. The tensile strength of the joint increases firstly and then decreases with the bonding temperature or holding time increases. Compared with 79 MPa which was the maximum value of Mo/Cu joint, the maximum tensile strength of joint with Ni interlayer was 97 MPa. The interfacial structure of the joints was studied by SEM, EPMA, EDS and XRD, the results showed that the different atoms diffused to each other in the bonding process and no intermetallic compound appeared. MoNi and NiCu solid solutions formed in the joint. The fracture of the joint had taken place in the Mo/Ni interface rather than in the Ni/Cu interface and the fracture way of the joints was brittle fracture.     

粉末钛合金的表面强化技术

低硬度和低耐磨性限制了钛合金尤其是粉末钛合金的实际应用.表面强化技术是提高粉末铁合金表面性能的有效手段之一.综述了近年来为提高钛合金表面硬度和耐磨性而采用的典型的表面强化技术,如激光表面改性、激光熔覆涂层、微孤氧化、离子注入、双层辉光离子渗和高频感应处理等.讨论了每种工艺方法的特点及其所获得表面强化层的结构和性能.最近,乌克兰国家科学院提出氮环境下钛合全的淬水技术,为钛合金表面强化提出了一个新的发展方向.     

航空发动机用先进高温钛合金材料技术研究与发展

新一代高推重比航空发动机压气机和涡轮系统高温环境使用的叶片、盘、机匣、整体叶盘和整体叶环等构件设计通常选用先进高温钛合金材料。本文综述近年来我国600℃高温钛合金、阻燃钛合金、TiAl合金、连续SiC纤维增强钛基复合材料及其应用技术取得的最新研究进展,并提出材料及构件设计、加工和使用亟待突破的关键技术,包括工业铸锭成分高纯化和均匀化控制技术、大规格棒材及特殊锻件制备技术、整体叶盘和整体叶环零件机械加工技术、材料性能评价及应用设计技术等。先进高温钛合金材料的不断应用将有力推动我国航空发动机技术发展。     

钛合金超塑性研究及应用现状

本文对钛合金超塑性研究和应用进行了综述,并对钛合金超塑性的发展方向进行了展望。     

水火弯板加热参数对钛合金板材组织和性能的影响

通过研究钛合金在不同加热参数下进行水火弯板后的组织和性能 ,分析了水火弯板的加热温度和加热次数对钛合金的组织和性能的影响。结果表明 ,在 60 0～ 90 0℃范围内进行水火弯板时 ,合金的性能同室温的相比 ,随着加热温度的升高 ,合金的σb 有所增加 ,而σ0 .2 和δ5均较大幅度地减小。随着加热次数的增加 ,合金的σb 和σ0 .2 逐渐增加 ,而δ5则逐渐减小。合金的塑性和韧性随着加热温度的升高和加热次数的增加而下降 ,这是由表面产生脆性层和晶粒长大所造成的     

船用钛合金与航空钛合金的使用性能差异

目前我国船用钛合金与航空钛合金已经形成特色鲜明、较为系统的合金体系.本文针对船用钛合金与航空钛合金的使用工况特点,分析了合金使用性能的差异,介绍了典型船用钛合金、航空钛合金的性能与应用情况,以及主要的发展方向.