Investigation into the wear behaviour of Stellite 6 during rotation as an unlubricated bearing at 600 °C

The wear behaviour of Stellite 6 was studied during rotational sliding in a bespoke bearing rig at 600 °C for times between 2 min and 12 h. Six stages of wear were identified: (i) formation of a mixed oxide ‘glaze’, (ii) cobalt and chromium elemental diffusion to the ‘glaze’ surface forming chromium- and cobalt-dominated oxide layers, (iii) oxygen diffusion into the ‘glaze’ leading to a chromium-dominated oxide layer at the ‘glaze’/substrate interface, (iv) spallation of the ‘glaze’ through chemical failure, (v) re-formation of the ‘glaze’ and (vi) elemental diffusion within the ‘glaze’, again resulting in discrete oxide layer formation.

► The wear properties of Stellite 6 were investigated in a bespoke bearing rig at 600 °C. ► Wear protective oxide films often referred to as ‘glazes’ were formed. ► During the formation of the ‘glazes’ discrete oxide films were formed within them. ► Eventually spallation of the ‘glaze’ occurred through chemical failure. ► A new ‘glaze’ was regenerated from the wear debris.