The tribological behaviour of self-mated ceramic composites, like SiC-
TiC, Si3N4-TiN and (Ti, Mo) (C, N) + Ni, were characterized under dry
sliding friction. The coefficient of friction still remain unchanged o
n a level known from SiC and Si3N4 ceramics. The addition of titanium
compounds to SiC and Si3N4 ceramics reduced the wear rate compared to
titanium-free ceramics. Increasing sliding speed and temperature enhan
ces 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(-7) mm(3)/N m UP to 800 degrees C. The present study has
by means of Small-Spot X-ray diffraction, Laser Raman Spectroscopy (L
RS) and Transmission Electron Microscopy (TEM) demonstrated, that TiO2
and crystalline Magneii-phases of Ti(n)O2(n-1)-type with a crystallog
raphic shear structure as well as some double oxides like NiTiO3, Mo0.
975Ti0.0025O2 and beta-NiMoO4 were detected on different ceramic subst
rates formed by tribo-oxidation during tests at 400 degrees C and 800
degrees C. The conditions during tribological operation are sufficient
to generate crystalline Magneli-type phases by tribo-oxidation, like
gamma-Ti3O5, Ti5O9 and Ti9O17. (C) 1998 Elsevier Science S.A. All righ
ts reserved.