THE EFFECTS OF OPERATING PARAMETERS AND ENVIRONMENT ON THE WEAR AND WEAR TRANSITION OF ALUMINA

Systematic wear tests were conducted with varying speeds, loads, tempe ratures and conditions of lubrication to investigate the influence of the operating parameters and environment on the wear and wear transiti ons of alumina. Time-dependent wear transition was observed in alumina without any lubrication. Water and paraffin oil significantly reduce wear and increase the wear transition load of alumina. For comparison, tests were also conducted in paraffin oil with other advanced ceramic s, e.g. silicon nitride, silicon carbide and zirconia. It was found th at alumina is comparable with other ceramics as far as the pre-transit ion wear resistance is concerned, however, the wear transition load fo r alumina is the lowest among the materials tested. The effects of gra in size and surface roughness on wear and wear transitions were also i nvestigated with specially processed aluminas. Surface roughness has a significant effect on the wear-in of alumina, however, the influence is diminished at the steady state wear stage. Different grain sizes ch ange the wear transition load and smaller grain size alumina has highe r wear transition resistance than larger grain size ones.