Wear engineering oxides/anti-wear oxides

Abstract

The tribological behaviour of self-mated ceramic composites, like SiCTiC, Si 3N 4TiN and (Ti,Mo)(C,N) + Ni, were characterized under dry sliding friction. The coefficient of friction still remain unchanged on a level known from SiC and Si 3N 4 ceramics. The addition of titanium compounds to SiC and Si 3N 4 ceramics reduced the wear rate compared to titanium-free ceramics. Increasing sliding speed and temperature enhances this trend. The (Ti,Mo)(C,N) materials exhibited a wear behaviour nearly independent from sliding speed and temperature with wear rates lower than 10 7mm 3/N m up to 800°C. The present study has by means of Small-Spot X-ray diffraction. Laser Raman Spectroscopy (LRS) and Transmission Electron Microscopy (TEM) demonstrated, that TiO 2 and crystalline Magnéli-phases of Ti n O 2 n type with a crystallographic shear structure as well as some double oxides like NiTiO 3, Mo 0.075Ti 0.025O 2 and β-NiMoO 4 were detected on different ceramic substrates formed by tribo-oxidation during tests at 400°C and 800°C. The conditions during tribological operation are sufficient to generate crystalline Magnèli-type phases by tribo-oxidation, like γ-Ti 3O 5, Ti 5O 9 and Ti 9O 17.