石墨对铜基自润滑材料高温摩擦磨损性能的影响

Effect of Graphite on the Friction and Wear Properties of Cu Alloy-Matrix Self-Lubricating Composites at Elevated Temperature

通过基体多元合金化和选用不同粒度的石墨颗粒,采用常规粉末冶金方法制备了铜基石墨固体自润滑材料,在大越式OAT-U型摩擦磨损试验机上考察了复合材料从室温到500℃温度条件下的摩擦磨损性能,利用扫描电子显微镜观察分析磨损表面形貌,进而探讨其摩擦磨损机理.结果表明:在室温条件下,石墨颗粒越小,则复合材料的摩擦系数越小,减摩自润滑效果越好;在室温至500℃条件下,选用合适的石墨粒度(0.3～0.5mm)和多元基体合金化,可使铜基石墨固体自润滑材料保持较好的自润滑特性.

Cu alloy-based self-lubricating composites filled with graphite of various grit sizes as a solid lubricant were prepared using conventional powder metallurgy combined with the alloying of the Cu-matrix with various metallic elements. The mechanical properties of the resulting composites were measured, while their friction and wear properties as sliding against Cr12 steel in a ring-on-block configuration at room temperature to elevated temperature of 500°C were evaluated using an OAT-U friction and wear tester. The worn surface morphologies of the Cu alloy matrix and the composites were analyzed by means of scanning electron microscopy, and the elemental composition on the worn surface of the Cu alloy matrix was determined using energy dispersive X-ray analysis. It was found that the mechanical and friction and wear properties of the Cu alloy-matrix self-lubricating composites were closely related to the content and grit size of the graphite as the solid lubricant. Namely, the smaller the particle size of the graphite was, the lower the friction coefficient and wear volume loss of the composites were. Moreover, it was feasible to effectively improving the friction-reducing and antiwear abilities of the Cu alloy-matrix composites by properly alloying of the matrix and carefully selecting the particle size of the graphite. The composite filled with the graphite of a grit size 0.300-0.500 mm at a mass fraction of 8% had the best friction-reducing and antiwear abilities at elevated temperature up to 500°C and could be used as a promising self-lubricating and wear-resistant material at elevated temperature.