石墨与BN添加对车离合器用铜基摩擦材料磨损性能的影响

Effect of graphite and BN addition on wear performance of copper-based friction material for vehicle clutches

研究了石墨与BN作为铜基摩擦片润滑成分时得到的车离合器用铜基摩擦材料的磨损性能,分析了制动压力、制动速度、温度对摩擦性能的影响。结果表明:铜基摩擦片的磨损率随石墨含量增加而减小,摩擦因数随BN含量提高而增大,加入3%的石墨与2%的BN(均为质量分数)组成的C2试样达到了最优的摩擦性能。当制动速度为1 000 r/min时,各试样的摩擦因数和磨损率均随温度上升而增大;当石墨含量增加以及BN含量减小后,试样摩擦因数的波动幅度也随之增加。摩擦试验后,C1试样中形成了较多的黑色块状石墨,并且在表层也覆盖了石墨润滑层。BN膜具有明显的小块分布特点,其稳定性低于连续性的大块石墨润滑层,较易在摩擦时被破坏掉并发生脱落,使基体发生磨损,引起磨损率的显著增大。综合运用BN和石墨可以达到比两种单一材料更优的润滑效果,从而同时获得常温与高温下的良好耐磨性。

The wear performance of copper-based friction materials for vehicle clutches were studied when graphite and BN were used as lubrication components,and the effects of braking pressure,braking speed and temperature on the friction properties were analyzed. The results show that the wear rate of copper-based friction plate decreases with the increase of graphite content,and the friction coefficient increases with the increase of BN content.The best friction performance is achieved by adding 3% graphite and 2% BN(both mass percent). When the braking speed is 1 000 r/min,the friction coefficient and wear rate of the samples increase with the temperature rising.When graphite content increases and BN content decreases,the fluctuation range of friction coefficient of the sample also increases. After the friction test,more black massive graphite is formed in C1 sample,and the surface layer is also covered with graphite lubrication layer. BN film has obvious small block distribution characteristics. Its stability is lower than that of continuous large block graphite lubrication layer. BN film is easy to be destroyed and fall off during friction,causing matrix wear and a significant increase in wear rate. The comprehensive application of BN and graphite can achieve better lubricating effect than two single materials,thus obtaining good wear resistance at both room temperature and high temperature.