饰品用银合金的研究进展

介绍了饰品用银合金的概况,重点综述了抗变色饰品银合金以及抗时效软化饰品银合金的最新研究进展,并对饰品银合金的发展进行了展望.     

抗变色仿金合金的研究

本文研究了合金化元素对仿金合金色译,抗变色性及加工工艺性能的作用。在Cu-Zn-Al系中(α+β＇)和β＇相合金具有金黄色译;适量的硅不仅使合金更加呈现金黄色译,而且使仿金合金抗变色性能提高;过高的含铝量并不能改善合金的抗变色性,3％Al是较佳含量,锌对于提高抗变色性有明显作用,高锌铜合金尤其具有较高的抗变色性。通过相同条件下对比试验,从96种仿金合金中优选出IG—01仿金合金,它在色译,抗变色性和加工工艺性上达到最优水平。     

载银锌4A沸石抗菌剂抗变色性能的研究

通过调整抗菌剂中银、锌离子的含量,研究了载银锌4A沸石抗菌剂的抗变色性能.利用ICPS测定了样品的银、锌含量,通过XRD、IR、TEM表征了抗菌剂的结构和形貌,并对其抗变色性能和抗菌性能进行了测试和分析.结果表明,减少ZLSZ抗菌剂中银离子(Ag )的含量,增加锌离子(Zn2 )的含量,抗菌剂样品的抗菌性能变化不大,而抗变色性能却大幅度提高.从抗菌剂的成本、抗菌性能和抗变色性能等方面综合考虑,载银锌4A沸石抗菌剂中,银含量为0.41wt%,锌含量为3.83wt%为宜.     

银变色研究的进展

世界铸币、展览、收藏等领域的银及其合金器件存在变色问题,现代工业中与银有关的部件的服役寿命、性能稳定性等一直被其变色困扰.为此,对银在氧、硫化氢、硫、二氧化硫、有机硫化物、氮氧化物、硫化物溶液、自由基和过氧化物、氯化物等腐蚀介质中的变色历程的研究进展进行了综述,概括了湿度、温度、光照、表面状态等因素对银变色的影响,提出了银变色研究面临的挑战和发展的方向.     

光亮氰化镀硬银在生产上的应用

前言氰化镀银早在一百多年前就已应用于装饰工艺品上,随着科学技术日益发展,目前不仅在装饰艺工品中,而且还廣泛应用于各类加工工艺品中,使用范围也由从纯装饰为主转为功能性为主,并有逐渐增长发展的趋势. 由于氰化镀银(俗称暗银)硬度低,耐磨性能差抗暗能力弱,特别是银金属与大气中痕量的SO_2、H_2S等作用生成变色膜,影响外观质量,增加镀件接触电阻,降低导电性和可焊性,在印刷线路板中造成短路,从而使产品蒙受巨大损失. 为了提高银层硬度、耐磨性能,抗变色性,特别是光亮性,我厂与上海光明电镀厂共同研制成功光亮氰化镀硬银(Ag-Sb)新工艺,并于一九八三年获得上海市重大科技成果三等奖. 新老工艺技术稳定性对比电镀光亮硬银(银锑)合金新工艺的研究,是     

NiAl金属间化合物的研究进展

对NiAl金属间化合物的国内外研究现状进行了系统综述,包括为改善NiAl合金力学性能和高温抗氧化性能等所采用的合金化、制备多相合金、制备复合材料、定向凝固、机械合金化、热压及热等静压、燃烧合成、微晶涂层等工艺,以及NiAl合金的超塑性行为,着重介绍及论述了合金化及定向凝固等工艺.简单介绍了NiAl合金的固溶强化磁行为.     

新型节银电接触材料的研究

研究了银合金－稀土胶体复合镀层的各种性能，包括镀层的摩擦系数、接触电阻的稳定性、镀层的耐磨性、可焊性镀层的抗变色性能以及电触点寿命试验等，并用扫描电镜、Ｘ射线衍射仪等对镀层的显微结构进行了分析。     

新型节银电接触材料的研究

研究了银合金－稀土胶体复合镀层的各种性能，包括镀层的摩擦系数、接触电阻的稳定性、镀层的耐磨性、可焊性镀层的抗变色性能以及电触点寿命试验等，并用扫描电镜、Ｘ射线衍射仪等对镀层的显微结构进行了分析。     

氮合金化堆焊硬面合金的抗冲蚀磨损性能研究

利用氮代替部分碳,通过铌、钒、钛固氮形成氮合金化堆焊硬面合金,进行了冲蚀角度30°抗冲蚀磨损性能实验,深入分析了冲蚀磨损机理。结果表明:高速含砂水流的冲击磨损,对硬面合金产生明显切削和犁沟剥落,其磨损机制主要为微切削磨损。氮合金化堆焊硬面合金中碳氮化物沿马氏体基体和晶界弥散析出,在强化基体金属提高硬度的同时能有效抵御冲蚀粒子的切削,增强抗冲蚀磨损性能,其磨损特征表现为冲蚀粒子冲击后留下的切削、犁沟以及碳氮化物处造成的块状剥离。     

机械合金化─研制生产金属材料的一种新工艺

本文介绍了机械合金化的工艺特点。用机械合金化技术可以获得一些常规方法难以制备的新型合金及难以获得的独特性能，如生产ＯＤＳ合金和弥散强化复合材料，扩大合金元素在基体中的固溶度，获得非晶态合金（金属玻璃），合成金属间化合物材料，获得纳米结构材料。在金属材料研制生产中，机械合金化是一项值得大力研究开发的新技术。     

AgCuZnSn钎料制备方法及合金化的研究进展

AgCuZnSn钎料作为绿色环保型硬钎料,一直是国内外钎焊学术界和产业界关注的热点。主要对近20年国内外有关AgCuZnSn钎料的研究报道进行评述,首先对AgCuZnSn钎料体系进行概述,其次从制备方法角度对现有AgCuZnSn钎料的研究进行了归纳分析,然后详细综述了AgCuZnSn钎料合金化的研究进展,分析元素In、Ga、Ni、P、Mn、La及合金Ni-P、Ga-In、Ga-In-Ce的调控作用,最后提出AgCuZnSn钎料研究和应用过程中存在的不足,并对其未来发展的方向进行了展望,为新型AgCuZnSn钎料的进一步研究提供理论指导和参考信息。     

过冷包晶合金的相选择分析

分析了过冷包晶铁基合金、铜基合金、稀土超导乳化物、稀土木磁化合物非平衡凝固过程中的相选择现象。根据对实验结果的分析，对过冷包晶合金凝固的相选择进行了分类。探讨了过冷包晶合金凝固今后的研究方向和应用前景。     

Degradable silver-based alloys

Noble metals solved in iron implants are effective cathodes, which can suit to accelerate the corrosion rate of the base material. In terms of its antibacterial behavior as well as lower costs in comparison with gold or platinum, silver seems to be an attractive candidate to adapt the corrosion rate of implants to the medical requirements. However, the degradation of silver in human bodies is a time-consuming process, and is controversially discussed due to the unknown long-term effect of silver on the human organism. Alloying silver with chemical elements less resistant to corrosion in aqueous mediums, particularly, in simulated body fluid, can improve the degradability of silver. Therefore, the current study addresses the design of adapted silver alloys exhibiting improved degradability in comparison with pure silver. Pure silver and binary silver alloys containing silicon, magnesium and calcium are studied in terms of their microstructure, open-circuit potential and degradation rate.     

Variations of color with alloying elements in Pd-free Au–Pt-based high noble dental alloys

The effects of alloying addition of a small amount of base metals (In, Sn, Fe, Zn) on color variations in Pd-free Au–Pt-based high noble dental alloys were investigated in terms of rectilinear and polar color coordinates. The ternary Au–Pt–X (X = In, Sn, Fe, Zn) and quaternary Au–Pt–In–Y (Y = Sn, Fe, Zn) alloys were prepared from high purity component metals. The amount of alloying base metals, X and Y, were restricted up to 2 at.%. The alloying addition of a small amount of Fe, In, Sn, to a binary Au–10 at.% Pt alloy (referred to as AP10) effectively increased chroma, C^*. On the other hand, the addition of Zn to the parent alloy AP10 did not change color coordinates greatly. The increase in chroma in the present Au–Pt-based high noble alloys was attributed to the increase in the slope of spectral reflectance curve at its absorption edge near 515 nm. It was found that the addition of a small amount of Fe to the parent alloy AP10 markedly increased lightness, L^*, and the addition of Sn gave a very light tint of red to the parent alloy. Although red–green chromaticity index a^* contributed to chroma to some extent, contribution of yellow–blue chromaticity index b^* was much greater in determining chroma in this Pd-free Au–Pt-based multi-component alloys. The present results are expected to be valuable in case color is to be taken into account in designing Pd-free Au–Pt-based high noble dental alloys.     

高熵合金制备及研究进展

高熵合金目前的研究大多针对块体、粉体、涂层、薄膜等领域,在其他领域的研究较少且缺乏统一分类。本文根据当前高熵合金研究进展,对所有研究的高熵合金种类进行了划分,介绍了元素选取原则,总结了高熵合金制备方法,综述了高熵合金研究机构、研究形式、研究内容等现状,展望了高熵合金应用前景,提出了当前高熵合金机理研究较少、性能研究不全面、热稳定性研究不系统、涂层制备工艺参数有待优化、轻质高熵合金设计、课题研究领域拓展等系列科学问题并给出针对解决方法,对于高熵合金课题未来的应用领域拓展研究方向有一定的指导意义。     

Ultraschallschweißen von Kontaktwerkstoffen

Ultrasonic Welding of Contact Materials . Ultrasonic welding of metals has found only a few industrial applications until now. Today however ultrasonic welding equipments with high power output for the welding of thicker parts are available. Contact materials have been welded ultrasonically on various base materials, e. g. silver and silver alloys on copper and copper alloys and aluminium. Bond quality was determined by shearing off the contact plates from the base material. Metallographic investigations and microhardness measurements were made to examine the bonding mechanisme. Ultrasonic welding will be a very good supplementary method in contact technology mainly for the welding of hardly weldable components like AgCdO or Al.     

银基钎料在制造业中的研究进展

钎料的性能很大程度上决定了钎焊接头的质量和钎料的应用范畴.银基钎料作为一类非常重要的硬钎焊材料,其填缝能力优异,强度与黄铜、低碳钢接近,可钎焊除铝、镁合金等轻金属之外的所有金属材料.因此,银基钎料广泛应用于航空航天、超硬工具等制造领域,并且受到国内外钎焊界学者们的高度关注.然而,银基钎料的发展及应用过程中仍存在以下问题:第一,钎料中贵金属银含量偏高(一般高于45%),导致钎料使用成本高;第二,银基钎料挤压、轧制、拉拔等加工过程中不可避免地存在夹杂物,影响钎料的使用性能和连接质量;第三,有益金属或合金调控钎料及其连接性能的机制较为复杂,尚未完全研究清楚;第四,传统制备银基钎料的方法产能低下;第五,银基钎料在制造业领域的应用研究尚未见系统报道.国内外对于银基钎料钎焊性能及工程应用方面的研究主要集中于:(1)开发多种节银降银钎料,主要是有益元素调控银基钎料连接性能方面的研究;(2)改进钎料的传统加工方法,提出新的制造方法,如粉末电磁压制成形、钎焊过程中原位合成、快速凝固、镀覆扩散组合等;(3)研究杂质元素(C、Ca、S、Al、Fe、Bi、Pb、O、N 等)的影响;(4)银基钎料形态创新研究,如三明治复合钎料(中间为铜合金、两边为银钎料)、箔带钎料、镀锡银钎料等;(5)工程应用研究,银基钎料在航空航天、汽车制造、电力能源等工业领域起着不可替代的作用,但目前国内外仍缺乏系统阐述该方面研究的报道.因此,本文对近20年国内外有关银基钎料的研究报道进行了评述,重点讨论了合金元素对银基钎料性能的影响.首先对银基钎料研究现状进行详述,总结了Cu、Zn、Sn、Ga、In、Ni、Mn、Cd、Li、Ce、La、P、Si、Pr在银基钎料中的优缺点,归纳了杂质元素C、S、O、N、Ca、Al、Fe、Pb、Bi的恶化作用.其次对银基钎料在航空航天、汽车制造、电力能源、超硬工具、家用电器、眼镜行业等制造业中的应用研究进行详细介绍.最后提出银基钎料研究和应用中的不足,为银基钎料的深入系统研究及相关技术发展提供理论指导.     

Mechanically alloyed metals

Abstract

Mechanical alloying involves the severe deformation of mixtures of powders until they form the most intimate of atomic solutions. Inert oxides can also be introduced to form a uniform dispersion of fine particles which strengthen the consolidated product. Large quantities of iron and nickel base alloys with unusual properties are produced commercially using this process. The theory describing the way in which the powders evolve into a solution is reviewed. There are some fundamental constraints which dictate how the microstructure must change during mechanical alloying for the process to be at all viable. The strange recrystallisation behaviour of the alloys can be understood if it is assumed that unlike normal metals, the grains in the mechanically alloyed sample are not topologically independent. Another topic discussed is the mechanical blending of microstructures containing different phases, both with and without a net reduction in free energy.     

High-temperature oxidation behaviour of base metal elements in nickel-base alloys

Oxidation of non-precious metals nickel, chromium and copper, nickel-base alloys in an air atmosphere was studied under differential thermal analysis. The results suggest that adding chromium and copper to high-purity nickel metal reduces the amount of oxidation and gives a slower oxidation than in untreated high-purity metals. It is then shown that the activation energy for oxidation in nickel-base alloys is almost the same as that in high-purity nickel metal when alloying elements are added to nickel.     

Enhanced strengthening and hardening via self-stabilized dislocation network in additively manufactured metals

The advent of additive manufacturing (AM) offers the possibility of creating high-performance metallic materials with unique microstructure. Ultrafine dislocation cell structure in AM metals is believed to play a critical role in strengthening and hardening. However, its behavior is typically considered to be associated with alloying elements. Here we report that dislocations in AM metallic materials are self-stabilized even without the alloying effect. The heating–cooling cycles that are inherent to laser power-bed-fusion processes can stabilize dislocation network in situ by forming Lomer locks and a complex dislocation network. This unique dislocation assembly blocks and accumulates dislocations for strengthening and steady strain hardening, thereby rendering better material strength but several folds improvements in uniform tensile elongation compared to those made by traditional methods. The principles of dislocation manipulation and self-assembly are applicable to metals/alloys obtained by conventional routes in turn, through a simple post-cyclic deformation processing that mimics the micromechanics of AM. This work demonstrates the capability of AM to locally tune dislocation structures and achieve high-performance metallic materials.