Friction performance of carbon/silicon carbide ceramic composite brakes in ambient air and water spray environment

We have examined friction performance, friction surface structure and chemistry of a carbon/silicon carbide ceramic brake disc tested against an organic pad in air, and water spray environment. An average friction coefficient of 0.52 and 0.4 for a braking stop is achieved after bedding in air for a composite disc comprising 53.1% and 17.7% SiC/Si, respectively. It is identified that 100% SiC/Si and ~50% Cf/C regions contribute the friction measurement. Tested in water spray, both brakes show a substantial fall of friction coefficient to a level <0.1. Evidences are provided for the existence of hydrodynamic friction. Friction transfer materials removal, SiC region polishing, and lower real contact pressure reinforce hydrodynamic process that a ceramic composite brake can experience.