Abstract:
Brake pad is the key component in the braking system of high-speed railway trains. Based on the friction performance collaborative regulation theory of powder metallurgy friction materials, the Cu-based friction material was designed. The performance of the brake pad was tested on the full-scale dynamometer, and characteristics of the friction film were analyzed in detail. The results show that the brake pad exhibits high stability of friction coefficient, low wear loss and the ability to protect the brake disc. Both instantaneous friction coefficient and average friction coefficient of the developed brake pad meet the requirements of TJ/CL307-2019 technical condition. The stability of friction coefficient is 0.0015. The recession of friction coefficient from 250 to 380 km?h-1 is as low as 0.027. The average friction coefficient at 380 km?h-1 remains at the relatively high value of 0.35, and the average wear loss are only 0.06 cm3?MJ-1, respectively. The excellent friction and braking performance of brake pads is attributed to the formation of the friction films with high strength, toughness and low transfer rate. The friction components with large particle size are used as external motion obstacles to nail the friction film. The submicron wear debris in the friction film serves as the meshing point between the friction film and the dual disc to provide friction resistance, thus maintaining the friction coefficient during high-speed braking. Oxides are continuously supplied by adding easily oxidized components, and the nanosized oxides generated by the severe grinding process are used as dispersion strengthening phase. The multi-scale particles are synergistically enhanced the dynamic stability of the friction film, and thus resulted in the excellent friction and wear performance of the brake pads.