Cu基粉末冶金闸片高速制动性能

High-speed braking properties of Cu-based powder metallurgy brake pads

Cu基粉末冶金闸片在高速制动时受温度的影响易发生摩擦系数的衰退,直接影响列车制动的有效性。利用1:1制动试验台进行不同速度下Cu基粉末冶金闸片的高速制动试验,分析试验后的摩擦材料和磨屑组织。结果表明:制动速度为350 km·h^(-1)和380 km·h^(-1)产生的高温使摩擦材料表层的金属基体发生软化熔融,降低了摩擦副表面微凸点的剪切阻力,导致摩擦系数下降。摩擦表面形成的金属氧化膜具有减磨作用,造成摩擦系数的进一步衰退。在380 km·h^(-1)制动时,石墨在高温下被氧化,摩擦表面失去稳定的润滑膜,出现粘着磨损和材料转移,磨耗量大幅增加。

Friction coefficients of the Cu-based powder metallurgical brake pads decline due to the high temperature during the high-speed braking,which will directly affect the train braking effectiveness.The 1:1 high-speed braking tests of Cu-based powder metallurgical brake pads were carried out under the different speeds,and the friction materials and abrasive texture after the tests were analyzed.The results show that,the metal matrix on the surface of friction materials melts due to the high temperature under the braking speeds of 350 km·h^(-1)and 380 km·h^(-1),decreases the shear resistance of the micro bumps on the friction surface,and causes the decline of friction coefficient.The metal oxide films formed on the friction surface reduce the wear,resulting in the further decline of friction coefficient.The friction surface lost the stable lubricant film when the graphite is oxidized under the high temperature generated by 380 km·h^(-1) braking,and the wear loss increases significantly due to the adhesive wear and material transfer behavior.