Powder processing and the fabrication of rhenium

In the past few years, the interest in rhenium and rhenium-containing alloys has increased. This interest is primarily due to results from investigations being carried out for high-temperature and space-reactor applications. High-purity rhenium metal has the potential to be used in larger quantities than ever before. These applications include rhenium in its pure form as well as in alloys with other refractory metals.     

An overview of rhenium effect in single-crystal superalloys

Nickel-based single-crystal superalloys are the key materials for the manufacturing and development of advanced aeroengines. Rhenium is a crucial alloying element in the advanced nickel-based single-crystal superalloys for its special strengthening effects. The addition of Re could effectively enhance the creep properties of the single-crystal superalloys; thus, the content of Re is considered as one of the characteristics in different-generation single-crystal superalloys. Owing to the fundamental importance of rhenium to nickel-based single-crystal superalloys, much progress has been made on understanding of the effect of rhenium in the single-crystal superalloys. While the effect of Re doping on the nickel-based superalloys is well documented, the origins of the so-called rhenium effect are still under debate. In this paper, the effect of Re doping on the single-crystal superalloys and progress in understanding the rhenium effect are reviewed. The characteristics of the d-states occupancy in the electronic structure of Re make it the slowest diffusion elements in the single-crystal superalloys, which is undoubtedly responsible for the rhenium effect, while the postulates of Re cluster and the enrichment of Re at the γ/γ′ interface are still under debate, and the synergistic action of Re with other alloying elements should be further studied. Additionally, the interaction of Re with interfacial dislocations seems to be a promising explanation for the rhenium effect. Finally, the addition of Ru could help suppress topologically close-packed (TCP) phase formation and strengthen the Re doping single-crystal superalloys. Understanding the mechanism of rhenium effect will be beneficial for the effective utilization of Re and the design of low-cost single-crystal superalloys.     

Recovery of rhenium from molybdenum and copper concentrates during the Looping Sulfide Oxidation process

Rhenium is recovered during pyrometallurgical processing of molybdenum sulfide and copper sulfide ores; the traditional technology involves removing rhenium(VII) oxide, Re₂O₇, from the sulfurous gas phase generated during multiple hearth roasting (in molybdenum processing) and smelting (in copper processing). A new technology platform called Looping Sulfide Oxidation (LSO) has been proposed to produce molybdenum and copper using alternative process chemistries. A detailed thermodynamic study of the reaction conditions used in LSO process indicates that rhenium recovery is possible at higher rates than currently realized in the industry. Conditions at which Re₂O₇ is reduced to rhenium metal by S₂ have been identified and key process conditions are outlined to maximize performance of the LSO scheme and rhenium recovery.     

混合嗜温细菌对辉钼矿中Cu、Mo和Re的生物浸出

运用响应面方法和中央复合旋转实验设计方法对辉钼矿生物浸出过程中影响铜、钼和铼浸出的一些工艺条件进行了建模与优化.基于中央复合旋转实验设计方法,考察了3个主要因素对生物浸出的影响,即料液pH值、矿浆浓度、接种体浓度,其值分别为:pH1.46～2.14,矿浆浓度0.95％～11.05％,接种体浓度1.59％～18.41％.根据中央复合旋转设计方法进行20组生物浸出实验.根据所得到的铜、钼和铼浸出率的实验结果,基于3个考察因素对其分别建立了经验公式.在实验条件范围内,根据经验公式采用二次方程对获得最大的铜、钼和铼浸出率的工艺条件进行了优化.结果表明,获得最大的铜浸出率的工艺条件为:pH=1.68,矿浆浓度0.95％,接种体浓度18.41％;在此条件下,钼和铼的浸出率分别为2.18％和24.41％.铜、钼和铼浸出率的预测结果与实验结果吻合较好.考察了生物浸出中黄钾铁矾生成对浸出的影响.     

Single-Crystal Rhenium-Bearing Nickel Alloys for Turbine Blades of GTE

The compositions of high-temperature single-crystal nickel alloys with rhenium additives (more than 6% Re), which have strength characteristics corresponding to foreign single-crystal alloys of the third generation, are determined. The attained level of properties justifies the use of the scarce and expensive element. An alloy with 9% Re belongs to the fourth generation of single-crystal high-temperature alloys where high-temperature strength and rhenium content are concerned.     

AAS法测定纯铼中痕量元素K试验研究

用AAS法测定纯铼中的痕量元素K。通过优化原子吸收测量条件,研究了硝酸用量以及基体铼对测定K含量的影响,建立了AAS法测定纯铼中痕量元素K的分析方法。结果表明,AAS法测量K的相对标准偏差不大于9.04%,测定范围为0.000 1%~0.001%,方法检出限为0.003 5μg/m L。本检测方法不仅准确可靠,而且简便快速。     

铼的资源、应用和提取

铼是一种重要的稀有金属,综述了铼的应用和国内外矿产和二次资源状况。介绍了从矿山和二次资源中生产铼的主要工艺流程,重点介绍了从Pt/Re重整废催化剂中回收铂和铼。     

Design of forging dies for forming flashless ring gear blanks using finite element methods

In the forging industry today, advanced mathematical techniques such as finite element methods (FEM) are beginning to revolutionize the conventional trial-and-error methods for die design and forging process development. Cost reduction programs are being implemented to enable the forging industry to remain competitive in today’s market. Material reduction or weight savings in the quantity of metal required to make the forged part is proving to be a significant factor contributing to cost reduction. Production of ring gear blanks without producing flash reduces the input weight of metal needed to make the gear blank, thus providing cost savings on the forged part. The following paper discusses different approaches currently used to make flashless ring gear blanks. The paper also describes the application of the rigid-viscoplastic finite element code “ALPID,” developed by Battelle Labs, Ohio, in developing a hot forging process to produce flashless ring gear blanks. The metal flow simulations, using ALPID, provide a tool to design and develop die cavities for defect-free closed die forging processes for making flashless ring gear blanks. The forming loads from these simulations are then applied to the forging die and the stresses on the die analyzed using another FEM based stress analysis package (“IDEAS,” developed by SDRC, Ohio) to verify the die design for strength in the given application. Thus, finite element methods were applied in different aspects of forging die design.     

A new,third-generation,single-crystal,casting superalloy

The CMSX®-10 alloy is a third-generation, single-crystal (SX), nickel-based casting alloy that is characterized by its 6 wt.% rhenium content, relatively high refractory element level (W+Ta + Re+Mo), and low level of chromium employment. Based on published data, the alloy's high-temperature creep-rupture resistance is greater than all other nickel-based alloys (approximately 30 °C better than CMSX-4 and PWA1484). Moreover, the alloy's composition is balanced to provide an attractive blend of SX component castability, heat treatability, impact strength, fatigue strength, and resistance to environmental degradation. Most notably, the alloy provides extremely good bare hot corrosion resistance, despite its novel and relatively low (2–3 wt.%) chromium content.     

铼元素分离富集研究进展

铼元素是一种可广泛应用于国防、航空航天以及新型科技领域的重要战略资源。铼元素在地壳中含量极低,是一种稀散金属,需要通过高效的分离富集才能获取。介绍近年来铼金属的冶炼/回收工艺流程及进展,综述近年来铼金属的冶炼/回收工艺流程及其进展,重点介绍可应用于铼富集分离的块体材料、纳米材料、生物质材料、介孔硅材料等新型吸附材料及其在铼一次资源与二次资源的开发与回收中的应用,并对铼富集与分离技术的发展进行展望。     

稀土钨电极在电推进系统中的耐烧蚀性能研究

阴极作为电弧加热发动机的“心脏”,担负着加热工质气体产生推进力的作用,由于卫星服役周期长,点火次数频繁,对阴极材料的寿命及耐烧损性能提出了很高的要求。为寻求耐烧损性能优异的阴极材料,以W-La-Ce-Y与W-La-Y-Zr电极为基础,采用氢还原-中频烧结的方法制备W-La-Ce-Y-Re与W-La-Y-Zr-Re电极材料。模拟发动机实际工况在250A电流下进行燃弧试验,测量燃弧后电极的质量损失并对电极尖端的组织形貌进行观察表征。结果表明,加铼电极在燃弧2h后的烧损质量更少,尖端形貌变化程度更小,耐烧损性能更好。在扫描电镜下观察到铼的加入抑制了尖端表面枝晶的生长,弱化了钨基体晶粒的再结晶程度,并探讨了稀土氧化物的迁移途径;在金相显微镜下观察到加铼电极的再结晶晶粒更细小,铼起到了细化再结晶晶粒的作用。在不同工作电流下测得加铼电极的阴极压降更低,铼的加入提升了电极材料的电子发射性能。     

Diffusion of potassium atoms into rhenium covered with two-dimensional graphite film

The effective diffusion of K atoms into Re (1010) stimulated by a graphite monolayer on its surface is discovered. The activation energies of the diffusion of potassium into rhenium and from it, as well as the effectiveness of the diffusion of potassium atoms, are determined. The following values are obtained: E _f1 = 5.4 ± 0.05 eV, E _1f = 5.75 ± 0.05 eV, and δ_dif(K) ≈ 0.25. The difference in the energies of the diffusion of potassium into rhenium is lower than the energy of the diffusion of potassium into iridium. It is shown that the diffusion length in the process of the diffusion of potassium adatoms into rhenium is greater than in the case of diffusion into iridium. The noticeable diffusion of potassium atoms are observed when the voltage U ≥ +200 V is applied to the specimen and intensifies approximately following the linear law as U increases to 4000 V. The formation of a graphite monolayer on the rhenium surface due to the enormous prolongation of the lifetime of K adatoms under the graphite island compared to the lifetime of adatoms on the exposed rhenium surface increases greatly the effectiveness of potassium diffusion, which grows by ～10⁸ times, then approaches unity. This phenomenon can be used as a method for the active alloying of subsurface layers of solids by atoms.     

Chemical vapor deposition of rhenium on a gourd shaped graphite substrate

Chemical vapor deposition (CVD) of rhenium coatings on a gourd shaped graphite substrate is studied. Effects of deposition temperature, chlorine flow rate, total pressure and chlorination temperature on deposition rate, yield, morphology and texture of rhenium coating are investigated, respectively. Uniform rhenium coatings have been obtained by using proper combination of deposition conditions at an acceptable deposition rate and yield. The rhenium coatings consist of two sub-layers, i.e., an inner nucleation layer of fine equiaxed grains and an outer layer comprising oriented columnar grains. Although different surface morphologies have been observed, the grains of rhenium coatings are all <002> oriented. The tendency of the preferred orientation <002> is more significant with decreasing surface roughness of the coating.     

化学气相沉积法制备铼材料的研究进展

铼具有优异的物理力学性能,作为功能材料及超高温结构材料获得广泛应用。铼材料的制备方法有多种,化学气相沉积（CVD）是其主要的制备方法之一。本文简要介绍了化学气相沉积制备铼材料的反应类型、沉积条件及沉积效果,综述了CVDRe材料的沉积动力学、组织结构特征、力学性能的研究现状和典型应用,并与粉末冶金铼进行了对比分析。最后指出了目前CVDRe材料研究亟待解决的关键问题,并对进一步研究的方向和推广应用前景进行了展望。     

夹杂物对套管抗硫化氢应力腐蚀性能的影响

对套管硫化氢应力腐蚀A法试验的早期断裂试样进行了分析.结果表明：B类条形氧化铝类夹杂物可引起硫化氢应力腐蚀A法试验早期断裂失效;表面及内部B类夹杂物形成的鱼眼型白点,均可成为裂纹源;D类球形氧化物夹杂作为裂纹源可引起硫化氢应力腐蚀A法试验断裂失效;改进炼钢工艺,采取各种措施减少夹杂物数量是提高抗硫套管硫化氢应力腐蚀A法试验通过率的重要途径之一.     

Rhenium Recovery By Solvent Extraction and Electrodeposition

A procedure developed by the US Bureau of Mines to recover rhenium in the form of electrolytic flakes by electrowinning the metal from a solvent-extraction strip solution is described. The recovered rhenium contains only about 0.1 % Mo and spectrograph traces of other impurities, such as copper, aluminum, calcium, chromium, iron, platinum, and silicon.The uses and properties of rhenium are discussed, and conventional recovery methods are reviewed.     

Rhenium Oxidation by Steam at High Temperatures

The kinetics of rhenium oxidation were studied under flowing steam+argon mixtures, at atmospheric total pressure and steam partial pressure in the range 24–74 kPa, and at temperatures from 1600°C up to 2200°C. No regime change was observed in the temperature dependence of the oxidation rate, which shows that the same chemical regime extends up to the highest temperature investigated. Moreover, at high temperature, the results showed a dependence of the oxidation rate on the gas velocity and the steam partial pressure, in good agreement with a gas-phase mass-transfer correlation for laminar flow, revealing that, for the conditions used, mass-transport processes in the gas phase also act as a limiting factor. It was assumed that the mass-transport limiting factor is the steam diffusion through a volatile oxides gaseous layer above the rhenium surface. A comparison of these results with rhenium oxidation rates reported for air leads us to propose the dissociative adsorption of the H₂O molecule as the limiting chemical stage of the oxidation process.     

High temperature fracture experiments on tungsten–rhenium alloys

A big problem when using tungsten as plasma facing components in a future fusion reactor is the very low fracture toughness at low temperatures. Tungsten–rhenium alloys outclasses other tungsten-based materials in terms of increased ductility. We study the reason for this positive effect by investigating the influence of rhenium on the fracture process of tungsten–rhenium alloys at different temperatures (between room temperature and 900 °C). The experiments are performed in a furnace-equipped tensile testing machine with a vacuum chamber, which allows us to perform fracture experiments at elevated temperature without oxidizing the material. Antecedent and subsequent electron backscattered diffraction scans are used to analyse the extent of plastic deformation and the interaction of plastic deformation and the fracture process. Furthermore, the consequences of recrystallization on the fracture process of tungsten–rhenium alloys will be analysed.     

Annual Indexes

In view of exploratory tests on rhenium plating carried out in previous work,¹⁶ a further study has lead to an improvement of existing formulations and to a better understanding of the mechanism of the discharge process. Deposit characteristics are improved by addition of magnesium sulphamate and aluminium compounds. Cathode efficiency for deposition of pure rhenium is low and, under preferred operating conditions, in the range of 10–20%; alloyed rhenium deposits can be obtained with higher cathode efficiency (80 to 90%).     

Further Studies of the Properties of Rhenium Metal

The thermoelectric behavior of the Pt—Pt-Re thermocouple and the resistance of rhenium to attack by certain molten metals is discussed. In addition, data are presented on the stress-rupture behavior of drawn wire, the tensile characteristics of rolled sheet, the variation of Young’s modulus with temperature, and the effect of specimen size and fabrication method on the work hardenability. Mechanical properties of thoriated rhenium are discussed. This includes data on the effect of thoria in rhenium on tensile properties, ductility, work hardening, and recrystallization.