Auger electron spectroscopy analysis of cross-section surface of oxidized titanium carbide single crystal

A TiC monocrystal was heated by three thermal cycles with isotherm at 1108 K while exposed to Ar/O-2 mixtures respectively with O-2 contents of 239, 1.0, and 324 ppm. The reactivity was detected with a homemade device based on two identical solid electrolyte oxygen sensors connected to a quadrupole mass spectrometer (QMS). The oxidized sample was cleaved by impact bending under high vacuum and the cross section investigated by Auger electron spectroscopy (AES) and scanning electron microscopy (SEM) techniques. Both area and profile AES spectra were acquired by using a 70 nm diameter beam. Spectral changes have been analyzed to identify chemical species present at the TiC/TiO2 interface. A model for high-temperature oxidation of TiC has been proposed. It implies oxygen diffusion through a protective TiO2 layer and the existence of two inner interfaces: TiC/TiC1-xOx and TiC1-xOx/TiO2.