Particle emission of organic brake pad material: A review

Abstract

Wear of a brake pad emits airborne particles and is a major environmental issue. This review paper deals with the analysis of different brake pad composite materials and their wear phenomenon. The volume fraction and size distribution of non-asbestos organic airborne particles emitted from the brake pad material with time, load and speed have also been discussed under different braking conditions. The airborne particles are measured by different aerosol instruments. TSI P-Trak, GRIMM aerosol spectrometer and scanning mobility particle sizer were used by different researchers for measuring ultrafine particles, micron-sized particles and aerodynamic nanoparticles, respectively. This paper shows that the wear particles emitted from the brake pad material vary in diameter between 10 nm and 10 μm under various loads and sliding velocities. These airborne particles such as coarse fine (diameters > 1 μm), fine (diameters between 100 nm and 1 μm) and ultrafine (diameters < 100 nm) particles are responsible for health hazards to the human respiratory system. This study has accumulated the data of different ingredients of the brake pad with airborne particle emission from various studies, which may be helpful for the evolution of new composite materials in the near future.