THE AFFECT OF SURFACE FINISH ON THE SLIDING WEAR OF ALUMINA

Two wear regimes were observed for a 95% alumina tested in dry sliding wear conditions using a pin on disc test geometry. Specimens prepared with lapped and polished surfaces exhibited low wear rates at applied loads of 10 and 40 N but ground surfaces wore rapidly at loads of 40 N and above. The surfaces that had experienced high wear rates contained more networks of microcracks and had rougher surface profiles than the mildly worn surfaces. X-ray line broadening analysis indicated that the wear debris had a particle size of 10 to 30 nm and contained plastic deformation, but no evidence of significant plastic deformation was found in the pin surfaces. Theoretical explanations are proposed for the existence of two types of wear behaviour: subsurface crack growth is believed to cause high wear rates, whilst low wear rates are due to a very fine scale abrasion of the surface. Recommendations are made on some of the precautions that should be taken to use alumina successfully in dry sliding wear applications. © 1990 Chapman and Hall Ltd.