The Influence Of Solid Lubricant On The Contact Stability Of Copper Matrix Composites

With the requirement of contact stability for the sliding electrical contact materials, traditional copper-graphite composite cannot meet this requirements because of its poor performance of wear resistance and electrical contact. In this paper, hot pressing process through protective atmosphere was used to prepare the copper and copper-tin based composites of different composition, electrolytic copper powder, CuSnlO alloy powder, graphite, MoS2and WS2powder were used as raw materials. The effect of solid lubricant and matrix on the mechanical, tribological and electrical contact properties of the composites was investigated. The friction coefficient, friction noise and electrical noise were used to evaluate the contact stability of the composites. The main results are as follows:(1) Use the Cu-24vol%Gr(Cu-6wt%Gr) composite as the standard, the result found that the mechanical properties and wear resistance of the copper matrix composites are improved when replacing the graphite with tungsten disulfide, the friction coefficient and wear rate of the Cu-24vol%WS2(Cu-21wt%WS2) composite are as low as0.156and7.61×10-14m3/N·m.(2) Use the (CuSn10)-6Gr composite as the standard, the effect of molybdenum disulfide and tungsten disulfide content on the friction and wear performances of the copper-tin matrix composites was investigated, the result found that with increasing content of molybdenum disulfide, the friction coefficient and wear rate of the composites decreased, when replacing the molybdenum disulfide with tungsten disulfide, the friction and wear properties of the (CuSn10)-6Gr-6WS2composite further improved, the wear rate is low to0.343×10-14m/N·m.(3) The contact voltage drop of the composites was discussed, the result found that the copper-tin matrix composites show a lower contact voltage drop than Cu-6Gr composite’s42.03mV, a low contact voltage drop can guarantee a good sliding contact between the brush and ring. With the increasing content of molybdenum disulfide, the contact voltage drop of the copper-tin matrix composites increases from18.92mV to33.62mV. when replacing the molybdenum disulfide with tungsten disulfide, the contact voltage drop of the (CuSn10)-6Gr-6WS2composite further improved, reaching31.43mV.(4) The contact stability of the composites was investigated, found that the mixture of graphite and tungsten disulfide can improve the friction coefficient stability of the copper matrix composites, and with the increasing content of lubricant, the friction coefficient stability of the copper-tin matrix composites improved. Friction noise is closely associated with friction coefficient, the greater the friction coefficient content, the greater the friction coefficient curve volatility, the more easy to issue a friction noise. The wear debris and the formation of lubricating film are closely associated with the electrical noise, the formation of a continuous lubricating film and less wear debris caused a low electrical noise.