Influence of friction material composition on airborne wear particle emissions from dry clutches

• Two different clutch materials for the same application are compared. • One material emitted higher particle mass, the other higher particle number. • Emitted particles consist of elements like Al, Fe, Cu, and Ba. • Materials consist of fibres and copper particles embedded in a matrix. • TEM analysis found two types of particle types, matrix and amorphous. Airborne wear particle emissions from dry clutches have been investigated in terms of particle mass and number concentration, size distribution, and chemical composition of a single clutch material. This paper presents a detailed continuation of the investigation. Clutch plates of two different friction materials, i.e., from different manufacturers but for the same automobile applications, are tested and compared under different running conditions. Online measurements are made of number and mass concentration as well as size distribution. Chemical composition is analysed of both collected particles and used and unused clutch disc surfaces. Particle morphology is studied using a transmission electron microscope. Results indicate that emission profiles of the two materials are different in terms of concentrations and composition, but both materials emit fine and ultrafine particles, and the emitted particles consist of elements like Al, Fe, Cu, and Ba.