Wear particle dynamics drive the difference between repeated and non-repeated reciprocated sliding

The dependence of the sliding mode (repeated vs. non-repeated reciprocated sliding) on the friction and wear behavior of ball-on-flat, brittle non-metallic interfaces in ambient air conditions is evaluated. Repeated sliding promotes the formation of a third body (compressed wear particles) that stabilizes the friction. Non-repeated sliding shows reduced evidence of third body formation, and instead a steady increase in friction. The proposed mechanism driving the non-repeated friction behavior is attributed to a gradual reduction in the ball surface roughness, leading to an increased area of real contact and greater capillary bridge forming across non-contact regions of the interface.