Powdered nitrile rubber @ silicon dioxide capsule as the wear modifier of phenolic resin composites under dry friction

Powdered nitrile rubber@ silicon dioxide (PNBR@SiO₂) capsules were successfully prepared based on the sol-gel method and introduced into phenolic resin composites (PRC) as wear modifiers. Results showed that PNBR@SiO₂ capsule modified PRC had slightly lower friction coefficient under diverse braking pressures and their wear rate at the braking pressure of 0.50 MPa was reduced by 97.3% than that of unmodified PRC owing to their excellent heat resistance, thus reducing adhesive wear. In contrast to PNBR modified PRC, the recession temperature on the friction coefficient of PNBR@SiO₂ capsule modified PRC increased from 250 °C to 300 °C and the wear rate at 350 °C decreased by 21.6%, which was attributed to the reduction of abrasive wear and fatigue wear.