On the influence of carbides in laser-cladded coating on friction, wear, and airborne particle emissions of disc brakes

Recently, it has become a focus to reduce non-exhaust aerosol emissions from the transport sector. One possible way to decrease brake particle emissions is by laser-cladding coatings onto brake discs. This work tested five different laser-cladding coated brake discs against a non-asbestos organic brake pad. The performance of these coatings was compared to a commercial grey cast iron brake disc tested against both low-metallic and non-asbestos organic brake pads. A specialized experimental system composed of a pin-on-disc tribometer, an aerodynamic particle sizer (APS) spectrometer, and a condensation particle counter (CPC) was employed to compare wear mass loss, coefficient of friction, particle number and mass concentration, and size distribution. The worn surfaces of pads and discs were analysed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results showed that the tungsten carbide-reinforced laser-cladded coating exhibited the lowest wear and particle number concentration compared to the other coatings and the commercial references. • Laser-cladded brake discs were tested in a pin-on-disc tribometer. • Novel carbides (SiC, WC, Cr 3 C 2 , TiC, Mo 2 C) were used for laser-cladded coatings. • Particle emissions and wear were measured and compared to a commercial reference. • Significant reduction in particle emissions was found for coated discs. • SEM-EDS shows material potentially being transmitted between the pin and disc.