Wear mechanism of Cu-based brake pad for high-speed train braking at speed of 380 km/h.

Cu-based brake pads for high-speed train were tested in full-scale at braking speeds as high as 380 km/h. The microstructure, composition and properties of the original, worn and lateral surfaces were investigated. The results show that a ~2 μm thick nanostructured tribolayer composed of CuO and Fe 2 O 3 was formed on the worn surface, owing to the plastic deformation, mechanical mixing, oxidation and sintering processes. The tribolayer enables significantly higher friction coefficient and wear resistance than original surface, which can be attributed to oxide-based composition and high hardness. The graphite particles in the worn and lateral surfaces were burned and the copper matrix was oxidized. The tribological property of brake pad highly depends on the composition and microstructure of the tribolayer. Image 1 • Cu-based brake pads for high-speed train were tested in full-scale braking at 380 km/h. • A nanostructured tribolayer composed of CuO and Fe 2 O 3 was formed on the worn surface. • The tribolayer enables high friction coefficient and excellent wear resistance. • Oxidation, delamination and spallation are the dominant wear mechanisms. [ABSTRACT FROM AUTHOR]