Friction and wear of the oxidized titanium in dry sliding against Co-28Cr-5W-4Fe-3Ni-1Si cobalt alloy

摘要

The results of conformal pin-on-disc tribological tests concerning the hard oxidised zone of the solid solution of oxygen in titanium-α, Ti(α)O, diffusely created during 2, 4 and 8 hours of oxidising in a superficial zone of the technical quality titanium specimen sliding against the Co-28Cr-5W-4Fe-3Ni-1 Si cobalt alloy counterspecimen are presented. The friction and wear responses of the system were recorded and the wear mechanisms were studied. Investigations of the material structure and chemical constitution in micro-areas of the titanium specimen, cobalt alloy counterspecimen and wear debris formed in dry sliding were performed on Philips XL20 microscope equipped with the Oxford Microspec WO x 400 analyser. Crushing of the Ti(α)O layer, lowering of the wear rate after comminution of the hard Ti(α)O layer, local tack spots and fine powder wear particles, mostly Ti oxides were detected at the beginning of each test. Gradual brittle fracture and decay by pulverising of the Ti(α)O particles embedded in both mating surfaces, which occurred during the test led to the increase of the wear rate of the couple and domination of the micro-cutting and tack spots spalling after their partial oxidation. Finally, after the disappearance of the Ti(α)O loose particles, adhesive junctions, metal transfer and smearing become leading wear mechanisms.