Rutile growth mechanism on TiC monocrystals by oxidation

The surfaces (111) and (110) of TiC single crystals have been exposed to an Ar/O-2 mixture at low oxygen content (approximate to270 ppm, P-tot = 2 bar abs.) and 1073 K. The oxygen consumption and interaction gaseous products have been detected, respectively, through zirconia stabilized oxygen sensors and a quadrupole mass spectrometer. The cross-sections of oxidized samples have been analyzed by micro-Raman and SEM techniques. Concentration profiles of amorphous carbon and rutile have been detected along the carbide oxidized layer interface. This confirms previous observations of retention of carbon during the oxidation of the transition metal carbides. The results obtained have been compared with our previous experiments which showed the following structural relationships: TiO2(200)\TiC(111) and TiO2(110)\TiC(110). The rutile (200) growth rate was found to be higher than the growth rate of rutile (110). Oxidation routes have been proposed.