ISSN   1004-0595

CN  62-1224/O4

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大电流对镀金铜配副载流摩擦学性能和磨损机理的影响

Current Load on the Triboelectric Properties and Wear Mechanisms of Gold-plated Copper Alloy Pairs

  • 摘要: 针对大功率电连接器背景下载流摩擦基础研究不足的问题,本工作中选用镀金黄铜与镀金铍青铜构成的球/平面接触摩擦副,在不同电流下进行往复滑动载流摩擦试验,探究大电流(电流密度高达26 A/mm2)对配副载流摩擦学性能和磨损机理的影响. 试验结果表明:对于界面摩擦磨损性能,无电流时摩擦系数较高,施加电流之后摩擦系数减小,而随着电流的增加(5~20A),摩擦系数逐渐增加,摩擦系数波动性随之减小;磨痕表面的粗糙度也随之增加,且电流大于15 A之后,粗糙度增加幅度相较于未磨损样品超过600%;磨损率也随电流的增加而变大,20 A时净磨损率转为负值,表明界面材料转移试样体积增加. 对于电性能,接触电阻和接触电阻波动性均随电流的增加而减小. 因此,电流的增加降低了摩擦磨损性能并劣化了接触表面质量,但却改善了电接触性能. 对于磨损机理,较低电流(5和10A)下,磨损机理以犁沟磨损和塑性形变为主;而较高电流(15和20A)下,开始出现黏着磨损. 计算分析表明:通入电流后,界面焦耳热功率远大于摩擦热功率,成为导致温升的主要因素. 电流为20 A时,有限元计算所得接触界面最高温度为78.0 ℃. 推测电流通入后的焦耳热温升引起材料软化,接触面积增加,从而导致摩擦系数的增加和接触电阻的减小;材料软化之后导致强度减小,促使了黏着磨损的发生. 该研究有望为大功率电连接器的配副材料设计和损伤防护提供理论支撑.

     

    Abstract: In order to investigate the current-carrying tribological properties and wear mechanisms of gold-plated copper alloy pairs under high electric current conditions based on high-power electrical connectors, the reciprocating sliding current-carrying friction tests were carried out under different electric currents (with current density up to 26 A/mm2) selecting a ball/plane contact pair composed of gold-plated brass and beryllium copper alloy in this work. Experimental results showed that under 0 A condition, the friction coefficient was relatively high and with electric current flowing through, the friction coefficient decreased. As the current increased from 5 A to 20 A, the friction coefficient gradually increased and the fluctuation of friction coefficient decreased. The surface roughness of the wear mark also increased, with its relative value higher than 600% compared with the unworn sample when the current above 15 A. The wear rate also increased with the increasing current, while the value turned negative at 20 A indicating that the sample volume increased due to the interface material transferring. As for electrical properties, the contact resistance and its fluctuation value both decreased as the current increasing. In summary, with the current increasing, the frictional and wear performances degraded and the quality of contact surface deteriorated, but the electrical contact properties improved. As for wear mechanisms, furrows and plastic deformations dominated at relative lower currents (5 A and 10 A), while adhesive wear made a great contribution at relative higher currents (15 A and 20 A). The calculational results demonstrated that that Joule heating power was much larger than the frictional heating power, which dictated the interfacial temperature rise. And the maximum temperature of the contact interface was 78.0 ℃ at 20A obtained by finite element calculation. Therefore, the temperature rise due to Joule heating led to material softening, resulting in the contact area increase, and thereby causing the rise of friction coefficient and the decrease of contact resistance. On the other hand, the strength decreased after material softening, which promoted adhesive wear. This study was expected to provide theoretical support for the material design and damage protection of the contact pair in high-power electrical connectors.

     

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