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用振动针-盘试验装置研究了金基合金(ASTM B541)和钯基合金(ASTM B540)偶的摩擦与接触电阻。测量分别在控制气氛为1大气压的干燥氦气,干燥二氧化碳和干燥空气,以及没有润滑的条件下进行。在后两种气氛中,振动初期的合金的摩擦系数很高,其后随振动次数增加而降到接近于0.2的稳定值。干燥氦气氛时的摩擦数据更不稳定。合金的摩擦系数对其接触表面的性能的敏感性比接触电阻低得多。在上述三种气氛时,振动开始时的合金的电阻一般都在1-10mΩ之间,随后通常会升高三个数量级,但此过程的重现性差,因为接触电阻波动很大是常见现象。虽然发现了电极化现象,但是由于接触电阻变化太大,以致未能鉴别它的作用。采用扫描俄歇显微镜及氩离子束溅射法,分析了磨痕表面成分及形态特征。分析发现:在三种气氛下形成的磨痕表面都有6nm厚的表面膜,膜的成分为S,Ag,Cu,C,O和Pd,Pd是以碎屑的形式从针上转移来的,表面膜中的S可能是以Ag和Cu的硫化物形式存在。接触电阻升高的动摩擦系数降低都可归因于磨痕表面生成硫化膜。
Friction and contact resistance of gold-based alloys (ASTM B541) and palladium-based alloys (ASTM B540) were investigated using a vibrating pin-plate test apparatus. Measurements were made under controlled atmosphere of 1 atmosphere of dry helium, dry carbon dioxide and dry air, respectively, and without lubrication. In the latter two atmospheres, the initial coefficient of friction of the alloy was high and then decreased to a stable value close to 0.2 as the number of vibrations increased. Friction data in a dry helium atmosphere is more unstable. The coefficient of friction of the alloy is much less sensitive to the properties of the contact surface than the contact resistance. In the above three atmospheres, the resistance of the alloy at the beginning of vibration is generally between 1 and 10 mΩ, and then typically increases by three orders of magnitude, but the reproducibility of this process is poor because it is common for the contact resistance to fluctuate widely. Although the phenomenon of electrode polarization was found, the effect of contact resistance changed so much that it failed to identify it. Scanning Auger microscope and argon ion beam sputtering method were used to analyze the surface composition and morphology of wear scar. It was found that the surface of the wear scar formed under the three atmospheres had a 6 nm thick surface film with the composition of S, Ag, Cu, C, O and Pd. Pd was transferred from the needle in the form of detritus , S in the surface film may be in the form of sulfide of Ag and Cu. Reduced coefficient of dynamic friction with increased contact resistance can be attributed to the formation of a cured film on the surface of the wear scar.