Effect of zirconium silicate and mullite with three different particle sizes on tribo performance in a non-asbestos brake pad

Abstract

This work aims to examine the effect of two different abrasives: zirconium silicate and mullite with three different particle sizes (5, 44 and 149 µm) on the frictional characteristics of brake pads. Six brake pads were developed using these two abrasives with three different sizes. The effect of the abrasives towards fade, recovery and wear was investigated by carrying out a tribological test in a Chase tester following SAE J661 standards. Results indicated that brake pads with coarser particles generated good fade resistance and acceptable recovery rate. This effect was explained based on the formation of a stable friction film observed through the field emission scanning electron microscopy and testing the microhardness at the surface of the samples after dry sliding. However coarser particles exhibited poor wear resistance. In comparison, smaller abrasive particles exhibited poor friction stability with excellent wear resistance. Detailed examination of the wear surfaces was conducted to identify the possible wear mechanism.