Ir-Re合金涂层的研究进展

铼-铱合金涂层具有优异的抗氧化性和耐冲刷性,可作为保护涂层应用于航空航天及工业领域。铱-铼合金涂层同时还具有优异耐高温、抗氧化等,在航天器等高温热防护方面有着重要的应用。本文主要介绍铱-铼合金涂层的性能、制备方法及其应用,同时展望铱-铼合金涂层的发展趋势。     

铼对铱显微组织和力学性能的影响

借助光学显微镜、扫描电镜和万能力学试验机研究元素铼对铱显微组织和力学性能的影响。结果表明,添加元素铼可以细化铱的晶粒,显著改善铱的显微组织。随着铼含量的增加,在固溶强化和细晶强化作用下,铱铼合金的屈服强度和抗拉强度呈现先上升后下降的趋势,当铼质量分数为7.0%时屈服强度和抗拉强度达到最大值为472.0和526.0 MPa;而在铱中添加铼以后,铱铼合金的延伸率先降后升,其中纯铱的延伸率最高为2.52%。室温下铱铼合金的断口呈脆性沿晶断裂和脆性穿晶断裂的混合断裂模式,加入元素铼后断口形貌中脆性穿晶断裂区域明显增多。     

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。     

生产铼部件的电子束物理气相沉积法

难熔金属铼是高温结构件和能源装置用的理想材料,如太阳能火箭发动机、热交换器、航天和导弹推进装置。它的优异耐蚀性能使它适用于高温火箭发动机和热气阀。铼有很高的熔点,仅次于钨,铼在高温下有最大的拉伸强度和蠕变断裂强度。因此,铼已被美国国防部的航天与导弹计划选用,用来制造导弹部件,包括推进器、调节阀管、供气管、拉杆、涂铼的球形件。然而由于铼冷加工硬化,每次加工变形5%～10%就需要完全再结晶退火。另外采用粉末冶金(PM)和化学气相沉积(CVD)很难制备铼部件。因为粉末冶金技术对于难熔金属的部件成形,遇到的困难很多,CVD方…     

熔盐电沉积法制备铱及铱合金涂层的研究进展

铱优异的理化性能使其成为高温抗氧化防护领域最重要的涂层材料之一。对制备铱涂层的多种方法进行了比较和分析,在此基础上,介绍了熔盐电沉积法制备铱及其合金涂层的装置和沉积前处理,讨论了熔盐体系、温度、电流密度及波形、环境气氛等工艺参数对涂层制备的影响,总结了铱及其合金涂层的性能和应用,指出了尚需研究的若干关键问题。     

钨铼合金制备工艺及其热负载行为的研究现状

钨凭借其优异的性能,已成为核聚变堆面向等离子体材料的候选材料之一。在核聚变堆运行过程中,钨将面临高热负载辐照、高氢/氦等离子体辐照和高能中子辐照。其中,钨经中子辐照后会产生嬗变元素铼,随着核聚变反应的进行,这些元素将在钨中持续产生和积累,形成嬗变产物钨铼合金。因此,钨面向等离子体材料的热力学参数和耐热负载性能会发生变化,这将关系到钨面向等离子体材料的服役性能,甚至关系到反应堆的稳定运行问题。目前,由于在实验室条件下核聚变高能中子的产生受限,故而对嬗变产物钨铼合金的研究主要基于实验室制备的钨铼合金。本文综述了现阶段钨铼合金的主要制备工艺及其热负载行为,分析了钨铼合金热辐照行为中存在的问题,希望能为未来核聚变堆中钨面向等离子体材料的早日应用提供参考。     

钼-铼粉末混合方法的研究

一、前言钼铼合金具有独特的性能,是制作空间反应堆堆芯加热管的最佳材料,对大规模集成电路技术应用来说,该合金也是最佳的材料,这是因为铼的加入,提高了合金的耐腐蚀性,同时也改善了合金的退火性能。     

Purolite A172树脂对铼和钼的静态分离

针对目前溶液体系中铼和钼分离困难的问题,通过树脂选型确定选用中强碱性阴离子交换树脂Purolite A172分离铼和钼,研究A172树脂对铼的吸附性能和对铼-钼的分离性能。结果表明:A172树脂吸附铼的反应为放热反应,而且吸附速率很大,吸附速率常数k_(298 K)=7.719×10~(-4) s~(-1),受内扩散控制,树脂对铼的静态饱和吸附容量达到340.13 mg/g湿树脂;当铼溶液pH=9、摇床往复震荡速率110 r/min、摇床水浴温度25℃、吸附时间1 h时,树脂对铼的吸附量最大;当以浓度为2 mol/L硫氰酸铵为解吸剂,在溶液pH=5、摇床往复震荡速率150 r/min、摇床水浴温度50℃下解吸5 h时,铼的解吸率最高,达到99.19%。大量的钼会阻碍铼的吸附,但随着吸附时间的延长,被吸附的钼逐渐被铼取代,铼和钼的分离因数最大值达到1192;解吸时,负载的钼对铼的解吸也有抑制作用,随着钼铼质量比的增加,铼的解吸率降低。     

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。     

AKS-W合金及其铼效应

铼能够同时提高钨、钼、铬的强度和塑性 ,人们把这种现象称为“铼效应”。添加少量 ( 3 %～ 5 % )的铼能够使钨的再结晶起始温度升高 3 0 0℃～ 5 0 0℃。用铼把含有铝、钾、硅的钨 (AKS -W )合金化 ,能够获得具有特殊性能的钨 (牌号BA)。为了保证铼在原料中的均匀分布 ,以铼酸铵的形式加入铼 ,使固态钨粉与液态铼酸铵的体积比为1:1,把坯料进行高温烧结 ,达到合金成分的完全均匀化。铼含量为 3w/%～ 5w/%的AKS -W合金具有良好的可加工性能 ,能够生产出微米尺寸 ( 13 μm～ 70 μm )的细丝。铼含量不超过 5w /%时 ,AKS -W合金的二次再…     

The properties and applications of rhenium produced by CVD

Rhenium possesses a unique combination of properties that make it an excellent choice for many applications demanding high-temperature strength, wear resistance and erosion resistance. While the major use of rhenium is still in bimetallic catalysts, renewed interest in improved propulsion and space-power systems has led to increased development of rhenium as a structural material. Recent investigations have illustrated the tremendous advantages of rhenium in certain structural applications.Thesuperior performance of rhenium can be attributed to its chemical inertness, superior high-temperature strength and room-temperature ductility. In several demanding applications, many of rhenium's properties can be optimally exploited by using chemical vapor deposition.     

微纳米LiFePO4正极材料的研究进展

纳米LiFePO4正极材料由于具有颗粒小、比表面积大的优势,是改善其动力学性能的有效手段,但由于较差的加工性能使其发展受限。通过纳微组装制备一次粒子为纳米颗粒,二次粒子为微米颗粒的微纳米LiFePO4正极材料可以改善纳米材料的加工性能。本文综述了近期微纳米LiFePO4正极材料的研究方向,主要介绍了规则形貌的微纳米LiFePO4正极材料的研究进展。     

Rhenium/Oxygen Interactions at Elevated Temperatures

The oxidation of pure rhenium was examined from 600 to 1400°C in oxygen/argon mixtures. Linear weight-loss kinetics were observed. Gas pressures, flow rates, and temperatures were methodically varied to determine the rate-controlling steps. The reaction at 600 and 800°C appeared to be controlled by a chemical-reaction step at the surface; whereas the higher-temperature reactions appeared to be controlled by gas-phase diffusion of oxygen to the rhenium surface. Attack of the rhenium appeared along grain boundaries and crystallographic planes.     

Metallic materials for structural applications beyond nickel-based superalloys

This paper reviews our current research activities on developing new multiphase metallic materials for structural applications with a temperature capability beyond 1,200°C. Two promising material systems have been chosen: first, alloys in the system Mo-Si-B which have demonstrated potential due to their high melting point of around 2,000°C and due to the formation of a protecting borosilicate glass layer on the surface at temperatures exceeding 900°C; and second, novel Co-Re-based alloys which have been chosen as a model system for complete miscibility between the elements cobalt and rhenium, offering the possibility of continuous increases of the melting point of the alloy through rhenium additions.     

深水作业机器人推进器布局建模及推力分配

为了研究遥控无人潜水器(ROV)水平推进器的安装位置与安装角度对ROV纵荡、横荡及艏摇三个运动的影响,建立了推进器空间布局与最终推力的数学模型.根据小型ROV的具体作业环境确定了推进器的安装角度,并在此基础上提出了功率归一与序列二次规划相结合的水平推进器推力分配方法,通过仿真验证了该方法进行推力分配的合理性和有效性.     

Ablation-resistant Ir/Re coating on C/C composites at ultra-high temperatures

An iridium/rhenium(Ir/Re)double-layer coating was prepared on carbon/carbon(C/C)composites by chemical vapor deposition(CVD)and electrodeposition.The morphologies and bond strengths of the coatings on the C/C substrate were examined.The ablation resistance of the Ir/Re coating was studied at 1800℃in an oxyacetylene torch flame for 300 s.The results show that Re interlayer increases the bond strength between Ir coating and C/C substrate by over 100%.During entire hightemperature ablation process,Ir/Re coating keeps intact without any signs of ablation damage.Ir coating gets smoother and the grain size becomes larger after ablation,with the preferred orientation changing from h311i to h220i:Although some voids are observed along the grain boundaries of the as-ablated Ir coating,Ir/Re coating keeps intact on C/C composites.The study indicates that Ir/Re coating can provide good ablation resistance up to 1800℃for C/C composites,especially for the continuous ablation applications.     

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.     

铼对CoNiCrAlY涂层合金抗热腐蚀性能的影响

对一种掺3%～5%(质量分数,下同)铼(Re)的CoNiCrAlY燃气轮机用高温涂层合金在1000℃进行热腐蚀实验,利用X射线衍射、SEM和EDS分析其热腐蚀行为。结果表明,无论掺杂Re与否,涂层合金均产生内氧化现象;与不掺杂Re的合金相比,CoNiCrAlY合金中Re的加入能够减小贫Al区的厚度,稳定α-Cr(Re)相,有利于Cr2O3氧化膜的形成,进而阻挡了熔融的Na2SO4与基体的接触,防止熔盐对基体的热腐蚀。     

Assessment of supply interruption of rhenium,recycling, processing sources and technologies

Rhenium is a unique, valuable and extremely rare chemical element currently used as an alloying element in high-temperature superalloys for aerospace and industrial gas-fired turbines and also as a catalyst in petrochemical industry. Moving towards a more competitive and sustainable economy requires access to this metal in adequate quantities and at competitive costs. However, minerals containing rhenium are generally found in very small quantities and are currently not commercially viable sources. Thus, the method and route for the extraction of primary rhenium is dependent on other metals (copper, molybdenum and uranium) of which rhenium is a by-product. In addition, focusing on alternative sources such as recycling of rhenium from waste alloy scrap and catalysts, is continually gaining attention in the research community. This paper has focused on the assessment of secondary sources of rhenium. The historical cost and also supply interruption indicators of rhenium were examined and assessed. Finally, opportunities of recovering and reusing existing stocks through Industrial Ecology are discussed.