制动条件下石墨对铜基摩擦材料瞬时摩擦性能的影响

Effect of Graphite on the Instantaneous Friction Properties of Copper-based Materials under Braking Conditions

为研究石墨对铜基摩擦材料瞬时摩擦性能的影响,采用粉末冶金技术制备铜-SiO2和铜-石墨-SiO2烧结材料,通过干摩擦惯性试验,在始末速度不同的制动区间,测试材料的瞬时摩擦因数、瞬时磨损率,并观察摩擦表面形貌的变化。结果表明:在高速度制动区间,石墨的存在使得铜基摩擦材料摩擦因数的稳定性明显提高,磨损率降低,原因在于铜-石墨-SiO2材料剥落石墨颗粒的分隔和保护作用,减弱冲击波动,从而提高瞬时摩擦因数稳定性并降低磨损;但较低制动速度时,石墨的存在反而提高了磨损率,原因在于摩擦层对颗粒的包裹度和基体强度降低。

In order to study the effect of graphite on the instantaneous friction properties of copper-based friction materials under braking conditions,the sintered materials of Cu-SiO2 and Cu-graphite-SiO2 were prepared by powder metallurgy.Through the inertia friction test,the instantaneous friction coefficient and wear rate of the materials were measured at different braking speeds,and the change of friction surface morphology was observed.The results show that,at high-speed braking range,the stability of friction coefficient of copper-based friction material after adding graphiteis significantly improved and the wear rate is reduced.This is because that the separation and protection of the exfoliated graphite particles of Cu-graphite-SiO2 material weakens the shock wave,improve the stability of the friction coefficient and reduce the wear.However,when the braking speed was low,the existence of graphite increases the wear rate,which was due to the decrease of particle inclusion and matrix strength of the friction layer.