贵金属阳极材料的应用与研究进展

贵金属阳极材料具有优异的电催化性能,为提高其催化活性,节能减耗减少其用量人们做了大量的研究。基于近十年来50余篇文献的分析,本文综述了贵金属阳极材料在基础化学工业的广泛应用及研究现状。展示了不同贵金属阳极的特点、发展历程和应用领域。介绍了贵金属氧化物阳极在电解水、氯碱工业、工业催化和废水处理等方面的应用进展,讨论了阳极材料的载体、控制形状、组成与物理化学特征之间的关系。对贵金属阳极材料的进一步发展及合理设计进行了展望。     

Stress corrosion cracking of noble metals and their alloys in solutions containing cations of the noble metal: Review of observations relevant to competing models of SCC

The stress corrosion cracking of Ag, Au and Cu-base alloys, and of pure Ag and Cu, has been studied by J.R. Galvele and others. These authors used solutions that contained the cation of the more-noble metal, so that the tested specimen was at or close to its equilibrium potential in the given solution. The opportunity is taken to review the history of this far-from-new observation and some of its implications. The role of the exchange current density in such cracking is discussed. Observations of Sieradzki and Torchio are used to suggest that in alloys such as brass, SCC is favoured by low,nothigh,surfacemobility, in line with the film-induced cleavage model, which requires very fine nanoporosity at the crack tip - such a favourable condition can only be achieved if dealloying is either very fast or occurs under conditions of low surface mobility. Observations of very slow intergranular SCC in pure metals under dynamic loading are interesting, but not really suggestive of mechanistic continuity with the dramatic mixed-mode cracking that occurs under static loading in brass or AuAg alloys. Torchio’s observations on brass U-bends in CuSO₄ solutions of various pH and Cu²⁺ concentrations are particularly hard to interpret using the surface mobility model.     

Progress in application of rare metals in superalloys

Rare metals play an important role in development of superalloys. Over the last two decades, the application of the rare metals in superalloys has achieved progress significantly. They present multi-beneficial effects for strengthening the matrix and the c0phase, increasing the lattice misfit, cleaning the grain boundary, improving the carbides and eutectics, refining the grain, stabilizing the oxidation film, etc., so that the elevated temperature rupture life and elevated temperature oxidation resistance are improved significantly, leading to a broad application in the superalloys. In order to meet the higher demand for better superalloys in the future, more intensive research is necessary on the effects of the rare metals on the superalloy, and especially on the combination effect of various rare metals and mutual influence among them. Utilization of the computational materials science and combinatorial high throughput experiment will be of importance in application of rare metals in superalloys.     

半固态金属加工技术研究现状与应用

半固态金属加工 (Semi SolidMetalProcessorSemi SolidMetalForming,简称SSM)是近年来金属加工技术研究的热点。总结了半固态金属成形的组织演变、流变行为以及坯料制备和成形工艺等方面理论与应用研究成果 ;对半固态成形技术的发展现状与趋势进行了分析和讨论 ;并从经济和市场需求角度分析半固态成形技术成本问题。介绍了半固态成形技术的应用范围 ,指出了半固态技术在汽车领域应用的广阔前景     

Thermochemistry of some binary alloys of noble metals (Cu, Ag, Au) and transition metals by high temperature direct synthesis calorimetry

The standard enthalpies of formation of some noble metal–transition metal compounds have been measured by high temperature direct synthesis calorimetry at 1372 K. The following results (in kJ/mol of atoms) are reported; Cu₅₁Zr₁₄, −24.3±2.2; Cu₃Pd, −7.6±1.2; Cu₅₁Hf₁₄, −22.9±2.3; Cu₃Pt, −10.8±1.1; AgTi, −1.6±2.4; AgTi₂, −2.3±1.1; Ag₂Y, −26.6±1.2; Au₂Sc, −83.4±1.8; Au₄Sc, −57.3±1.5; AuMn, −25.3±1.7; Au₂Y, −84.6±1.8; Au₃Y, −69.1±1.9; Au₃Pd, −7.9±1.9. The results are compared with some earlier experimental values obtained by EMF, by vapor pressure and by calorimetry. They are also compared with the predicted values of Miedema and coworkers. We will present a systematic picture of how the enthalpies of formation may be related to the atomic number of the transition metal.     

高频感应焊接的特点及其在异种金属焊接中的应用

回顾了高频感应的定义和发展,介绍了高频感应加热焊接的基本原理和其加热速度快,焊接热影响区小,能量集中,冷却时间短以及环保、节能等特点.针对异种金属焊接存在的难点,综述了常用的焊接方法及其优缺点.高频感应焊的快速加热和表面集肤效应的特点,使其能够实现异种金属钎焊和表面熔覆焊的冶金结合,接头性能优良.指出感应圈的形状及其与...     

The application of “ice on mud” theory to the fretting corrosion of metals

The ice on mud analogy of Bowden and Tabor has been used to elucidate the mechanism of fretting corrosion on metals. It has been shown that higher falls in free potential on fretting would be observed for metals whose oxides are appreciably harder than the underlying metals.     

硬钎料挤压的研究与应用现状浅析

从硬钎料的热挤压研究及应用现状谈起,分析了影响钎料热挤压的装备功能、模具性能和工艺因素(速度、温度、变形指数、模具形状)。结合生产实际阐述了常用的挤压装备、经典挤压工艺和主要的模具失效形式及其原因,并针对失效形式提出了提高挤压模具使用寿命、稳定产品质量、提高生产效率的多项技术措施;探讨了提高钎料热挤压质量和效率的技术途径。调查研究发现,优良的装备、适宜的工艺和合理的模具设计是热挤压顺利进行的根本保证;模具材料、模具制造工艺和使用制度决定着模具使用的稳定性。     

异种金属爆炸焊接窗口分析与应用

爆炸焊接窗口是获得良好结合质量的重要方法,计算的理论模型和参数选择对结果至关重要. 从爆炸焊接参数出发,通过分析爆炸焊接窗口边界公式的发展历程、理论假设和参数选择,总结得到方便使用的窗口计算公式. 将其应用到钛/铝焊接中,分析了钛与不同牌号铝合金的焊接方式,预测了不同装药比时焊接界面的质量. 结果表明,随着铝合金硬度的升高,可焊窗口逐渐减小. 当焊接参数位于窗口中部时,界面成小波状,结合质量好;焊接参数接近窗口上限时,界面成大波状,存在大量微观缺陷.焊接窗口是重要的研究手段,能够较好的指导生产实践.     

Solid-state welding of metals with application of high density current pulses

The results of solid-state welding of homogeneous and heterogeneous metals with application of high density current pulses are presented. A chart of the current treatment allowing obtaining of the welded joint at its heating in an air atmosphere is proposed. The influence of alternating and unipolar current on the deformation of contact surface microroughnesses in the welding zone is considered. The basic parameters of the pulse current and the specific energy of the treatment of steel and copper samples that ensure obtaining of the welded joint are determined.     

Practical application of ion implantation for modifying tribological properties of metals

The possibility of applying ion implantation to the reduction of wear has been known and investigated for more than a decade. However, industrial application is still very limited.To evaluate the difficulties of applying published data to practical applications, a varied selection of tools were nitrogen ion implanted and tested in true industrial working situations. For appropriate applications, tool life was increased by factors in the range 2 – 9. A preliminary attempt has been made to categorize tool materials, applications and improvement factors.Seven principal factors have been identified which have impeded the propagation of this technology in industry. It is concluded that, before widespread industrial application is realized, more efficient and higher throughput commercial ion implanters must be available, in addition to more extensive data on practical applications.     

The application of a ductile fracture criterion to the prediction of the forming limit of sheet metals

To predict accurately the forming limit in sheet metal forming, the combination of FE simulation with tension tests is adopted in this paper to determine the material constants p and C in a ductile fracture criterion (DFC), which is advanced by the author. Forming limits of bore-expanding, hemispherical punch bulging and deep drawing (cylindrical, square-cup parts) are predicted by means of the DFC. Comparison of the results predicted by the DFC with experimental values shows that the precision of forming limit predicted by material constants obtained by the combination method is more accurate than that predicted by material constants obtained by the tension method, and that the critical punch stoke and the fracture initiation position in forming processes above mentioned are predicted accurately by the DFC.     

金属爆炸焊接数值计算及工程应用

利用经典近似公式对炸药敷设厚度、有效多方指数、碰撞角和安装间距之间的可焊范围进行了数值计算分析，并对2号岩石硝铵炸药的爆速随其装药密度及敷设厚度给出了定性、定量的描述，经试验验证在工程中应用是可行的。     

贵金属高温结构材料的强化及应用

铂族金属具有高熔点、高温抗氧化性、高的抗腐蚀性能及较高的高温强度等一系列性能特点,作为高温抗氧化耐腐蚀结构材料具有重要应用。基于对50余篇文献的分析,综述了铂族金属高温结构材料的强化机制及应用研究进展,并对未来铂族金属高温结构的研究方向进行了展望。