Role of the friction layer formed on the brake lining surface in friction stabilization for automotive brakes

This study highlights the frictional behavior of the disc brake interfaces and microstructure of the friction layers (FL) and transferred materials (TM) on the tribopairs. The designed dynamometer was utilized to evaluate the frictional performance of the disc brake materials during dry sliding under different braking events (applied loads and speeds). The morphological properties of the brake lining and disc surfaces were examined by EPMA, FESEM, EDS, 3D surface profilometry and Raman spectroscopy to illustrate the FL, TM and wear mechanisms. The tribo-braking results exhibited that the friction coefficient (FC) increased with increasing the applied load. This is due to the fact that, at high applied loads, the actual contacting area of the friction pair is increased resulting in the growth of the secondary contact plateaus and flattening of primary contact plateaus that help the enrichment of the FL. Whilst, the initial stop-braking speeds did not hugely affect the FC. Eventually, the formation and destruction of the FL showed a significant role in controlling the brake friction behavior. The formation of the FL increases the frictional stabilization.