Influence of Silica as an Abrasive on Friction Performance of Polyimide-Matrix Composites

This study investigated the friction performance of polyimide-matrix composites with various silica powder contents of different sizes. The friction tests were performed on a pin-on-disk tester at various velocities, ranging from 30 to 160 km/h. The experimental results indicate a silica powder size of 0.25±0.05 mm, a sample of 4 wt.% SiO ₂ demonstrated a high friction coefficient and better wear performance as compared to a sample without silica. The influence of silica content and powder size on the friction coefficient is directly related to the friction velocity. At low friction velocity (30–90 km/h), the friction coefficient increases as the SiO ₂ content increases, but decreases with increasing SiO ₂ particle size. At high friction velocity (90–160 km/h), the content and particle size of SiO ₂ have little influence on the friction coefficient. Experimental results indicate that large SiO ₂ particles can effectively hinder the motion of third body, which is advantageous to the formation of a compact third body and to the protection of the friction surface.