Hydrothermal oxidation of silicon carbide and its bearing on wet wear mechanism

Static hydrothermal oxidation experiments in a diamond anvil apparatus using wafer-quality single-crystal silicon carbide and observations from transmission electron microscopy from tribolgical tests on sintered silicon carbide are combined to gain insight into the wear process in water. The evidence points to an active type of oxidation under hydrothermal conditions, i.e. there are no primary condensed reaction products. The formed tribolayer is topographically highly variable and consists of dissambled silicon carbide (µm to nm-scaled), which contains secondary, precipitated silica in cracks and voids or as a glue in areas between original asperities. Hydrothermal pressures of several hundred MPa seem feasible and are seen as responsible both for fatigue and surface roughening as well as the formation of the smooth main wear track, which reduces friction favourably.