Tribological properties of polymer/silica composite coatings for microsystems applications

The tribological properties of composite coatings consisting of silica nanoparticles dispersed in either a poly-methylmethacrylate (PMMA) or polystyrene (PS) matrix were assessed. The experiments were conducted using a reciprocating type of micro-tribotester under relatively low normal loads ranging from 5 to 15 mN. Results indicated that the wear resistance of PMMA could be significantly improved by adding silica particles at the cost of increased friction coefficient from 0.27 to 0.4. The effect of silica content on the wear resistance of PS was less apparent. Such outcome was attributed to the difference in the compatibility between silica and the polymer matrix.