Investigation of Brake Emissions of Different Brake Pad Materials with Regard to Particle Mass (PM) and Particle Number (PN)

Non-exhaust PM₁₀ emissions are coming increasingly into focus of both regulation and media coverage. This will in coming years pose a challenge to the mobility sector as a whole and to the automobile industry in particular. To master this challenge, an in depth knowledge of the underlying processes of particle generation and emission is needed. As a contribution to this effort, the present study investigates the influence of different friction materials and disc types on brake emissions. It show that a well-performed brake emission measurement on a brake dynamometer can provide valuable information about both basic influencing factors and material-specific emission behavior. The results clearly indicate a correlation between the mass of PM₁₀ emissions and total wear as well as a temperature dependency of the number of emitted particles (PN emissions) for grey cast iron brake discs. It is shown that coated discs have the ability to significantly reduce PN emissions especially in the small particle size range. The presented measurement method and evaluation strategy enables future friction material development that is aiming at low emission brake systems.