树脂包覆石墨/铜复合材料的高温和载流摩擦磨损性能

High temperature and current-carrying friction and wear properties of resin-coated graphite/copper composites

以酚醛树脂粉末、石墨粉、镀铜石墨粉和电解铜粉为原料,采用冷压−加压烧结工艺分别制备树脂包覆石墨/铜和镀铜石墨/铜复合材料,研究两种石墨/铜复合材料的室温、高温以及载流条件下的摩擦磨损性能,并与国外Roland接地电刷进行对比;结合高温(200~600℃)下铜基体晶体结构与材料导电和力学性能的变化规律,分析树脂持续分解对复合材料导电、力学和摩擦磨损性能的影响规律。结果表明:树脂包覆石墨/铜复合材料的高温力学性能优于镀铜石墨/铜复合材料,环境温度达到600℃时,树脂包覆石墨/铜复合材料的剪切强度仅降低6%,而镀铜石墨/铜复合材料的降幅达到24%。树脂包覆石墨/铜复合材料的高温(250℃)耐磨性和摩擦稳定性远优于镀铜石墨/铜复合材料和Roland电刷,载流摩擦因数低于Roland电刷。石墨的树脂包覆能改善铜基复合材料的高温和载流摩擦磨损性能,由于树脂层的保护,石墨即使在高温和载流条件下,也能形成连续完整且稳定的润滑膜,减少摩擦接触的微间隙;摩擦时炭化的树脂破碎成细小硬质颗粒,阻碍材料与对磨盘的黏着磨损;高温下铜基体软化不明显,可减少电弧的发生。

Resin-coated graphite/copper composites and copper-plated graphite/copper composites were prepared by cold pressing-pressure sintering process using phenolic resin powder,graphite powder,copper-plated graphite powder and electrolytic copper powder as raw materials,respectively,the friction and wear properties of two kinds of graphite/copper composites at room temperature,high temperature and current-carrying were studied,and compared with overseas Roland grounding brush;the effects of resin decomposition on the conductivity,mechanical and friction and wear properties of the composites were analyzed based on the crystal structure of copper matrix and the variation of composite conductivity and mechanical properties at high temperature(200−600℃).The results show that the mechanical properties of resin-coated graphite/copper composites at high temperature are better than that of copper-plated graphite/copper composites.When the ambient temperature reaches 600℃,the shear strength of resin-coated graphite/copper composites decreases by only 6%,while that of copper-plated graphite/copper composites decreases by 24%.The high temperature(250℃)wear resistance and friction stability of resin-coated graphite/copper composites are much better than those of copper-plated graphite/copper composites and Roland brush,the current-carrying friction factor of the resin-coated graphite/copper composites is lower than that of Roland brush.The resin coating of graphite can improve the friction and wear properties of copper matrix composites at high temperature and current-carrying,due to the protection of the resin layer,a continuous and stable graphite lubricating film can be formed even under the conditions of high temperature oxygen and current-carrying,thus reducing the friction contact micro-gap;the carbonized resin breaks into fine hard particles during the friction,which hinder the adhesion and wear between composite and disc;the Cu matrix softening at high temperature is not obvious,so the occurrence of arc decreases.