WEAR MECHANISMS OF ALPHA-ALUMINA LUBRICATED WITH A PARAFFIN OIL

The effect of load, sliding speed and lubricant temperature on the tribological performance of polycrystalline alpha-alumina was investigated. A four-ball test geometry was used with a purified paraffin oil lubricant. The test results showed that the wear behavior of this material was strongly dependent on the contact load. Mild to severe wear transitions occurred at particular loads, depending on lubricant temperature and sliding speed. The transition load was found to decrease as either the lubricant temperature or the sliding speed was increased. The onset of transition is explained by the failure of the lubricating film due to an increase in flash temperature. Examination of the worn surfaces by scanning electron microscopy revealed that intergranular fracture was the primary mechanism for severe wear.