X-Ray Photoelectron Spectroscopy Study of the Metal/Cermet Interface

Interfacial reactions between aluminium and polycrystalline cermet TiC_0.6 were investigated using x-ray photoelectron spectroscopy, Auger electron spectroscopy and x-ray diffraction. It was found that titanium exists in two chemical states. The carbide and oxide of titanium can be detected simultaneously, and the atomic ratio of Ti:C:O is 5:3:2. This suggests that TiC_0.6 is a Ti-oxycarbide or oxygenated TiC composite: Ti₅C₃O₂(TiO₂+4TiC_0.75). When Al is deposited in vacuum on the Ti-oxycarbide surface, the active Al atoms react chemically only with TiO₂at room temperature, but not with Tic_0.75 in Ti-oxycarbide. The reaction products are Al₂O₃ and the intermetallic compound Al₃Ti. Annealing the Al/TiC_0.6 interface at 750°C Al reacts also with TiC_0.75 to form a brittle Al₄C₃ phase.