Tribological properties of solid lubricants (graphite, h-BN) for Cu-based P/M friction composites

Cu-based P/M friction composites containing graphite at weight fractions in the range of 0%, 2%, 5%, 8%, 10%, corresponding to the hexagonal boron nitride (h-BN) at weight fractions in the range of 10%, 8%, 5%, 2%, 0%, were fabricated by a P/M hot press method, respectively. The effects of graphite and h-BN on tribological properties of Cu-based P/M friction composites were investigated on a block-on-ring tester. Worn surfaces, microstructures and wear debris of the composites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results indicate that lubrication effects of graphite are superior to those of h-BN. With the increase of graphite content wear rates were decreased significantly. Added graphite with low contents of h-BN can stabilize friction and wear properties of Cu-based P/M friction composites.