The correlation between thermal conductivity and wear rate of composite friction materials

During the engagement of a dry clutch system heat is generated at the friction surfaces and the temperature rise caused by this heat depends on the thermal properties of the clutch facings. Usually these facings are made of polymer matrix composite friction materials and they have a low thermal conductivity. Any increase in the thermal conductivity of these materials is expected to reduce the contact surface temperature and improve their tribological performance. The thermal conductivity of six polymer matrix composite friction materials was measured at room temperature, 100ºC, 200ºC, and 300ºC using the laser flash diffusivity technique with density corrections for these temperatures. The wear rate of the materials was measured in the low energy test, medium energy test, and high energy test according to standard norms for clutch facings testing. The correlation analysis between thermal conductivity and wear rate for the materials and conditions studied did not confirm the expected relation between high thermal conductivity and low wear rate. Wear is a system property and it can not be considered as a material property. Obviously there are other variables which were not studied on this work with a more significant impact on the wear behavior of the materials