Effect of alumina content on the thermal, mechanical and tribological properties of resin‐based friction materials

Abstract

To investigate the effect of alumina on the thermal, mechanical, and tribological properties of resin‐based friction materials, five friction materials with different alumina contents were prepared by the hot press molding process. The experimental results showed denser friction materials possessed higher hardness, while compressive strength and compression modulus dropped as alumina decreased. Friction material with 6 wt% alumina exhibited outstanding impact strength and great heat resistance. It also showed excellent friction stability, with a maximum mean coefficient of friction (COF) steady between 0.408 and 0.425 at various braking speeds. The wear resistance of friction materials had a positive relationship with the stability of the COF, and the greater the stability of the COF, the better the wear resistance and the lower the corresponding wear rate. The morphology of the worn surface indicated multiple sources of friction at different braking speeds, and large areas of dense friction films were beneficial to stabilizing the COF and reducing the wear rate.Highlights The sample with 6 wt% alumina showed excellent heat resistance, with a residual value of 83.5% at 800°C. The highest compressive strength and compression modulus were achieved in the sample with 8 wt% alumina. The sample containing 6 wt% alumina exhibited the highest COF and the lowest wear rate. The maximum subsurface temperature of the friction materials basically rose as braking speed increased. Large areas of dense friction films were beneficial to stabilizing the COF and reducing the wear rate.