Performance of ceramic enhanced phenolic matrix brake lining materials for automotive brake linings

Despite the number of research studies completed on the mechanism of friction in automotive brake lining materials, the phenomenon is still not fully understood. Complex mechano-chemical processes occurring on the friction interface of a composite friction material make it difficult to understand the correlation between the formulation of brake lining and the frictional performance. This paper concentrates on (i) the friction and wear characteristics of a newly formulated brake lining material, and (ii) the impact of potassium titanate on its performance. Two different material samples were formulated, tested and analyzed. The friction and wear characteristics of the first (without potassium titanate) and second (with potassium titanate) sample types were determined using the Friction Assessment and Screening Test (FAST) and a full-scale single-ended inertial type disc brake automotive dynamometer test. Friction coefficient, wear rate, and friction surfaces were examined to interpret the performance of the two friction materials. The friction surfaces of the samples were investigated by light microscopy, scanning and transmission electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction analysis. Analysis of the experimental results shows that the brake lining material containing potassium titanate significantly improved the stability of the friction coefficient, fade and wear resistance. This improved performance was attributed to the formation of a Ti and K-oxide containing friction layer, which developed in the initial stage of the frictional testing.