Wear behavior of graphite-fiber-reinforced glass

Composites of borosilicate glass reinforced with high strength, high modulus and ultrahigh modulus (UHM) graphite fibers were tested for wear against a cast iron counterface in a pin-on-disk configuration at sliding velocities of 0.24, 0.60 and 0.96 m s −1 under a load of 5 MPa. Discontinuous fiber-reinforced composites generally exhibited higher wear rates and friction coefficients than the continuous fiber-reinforced systems. Continuous UHM fiber-reinforced pins exhibited the lowest wear rate. It is shown that the wear rate depends on the strength and dimensions of the graphite filaments. Two types of wear, mild and severe, were observed at low and high sliding velocities. Mild wear is characterized by a smooth thin stable film on both the pin and the counterface with minimal pitting and plastic deformation of the cast iron. Severe wear is characterized by rough pitted surfaces on the pin and the counterface accompanied by a thick film on the counterface. A proposed mechanism of wear of unidirectional graphite-fiber-reinforced composites which incorporates the transition between mild and severe wear can explain the phenomenological observations.