OXIDATION OF TI3SIC2 IN AIR

Polycrystalline samples of Ti3SiC2 were oxidized in air in the 900 to 1400 degrees C temperature range. The oxidation was parabolic with par abolic rate constants, k(p), that increased from 1 x 10(-9) to 1 x 10( -4) kg(2) m(-4) s(-1) as the temperature increased from 900 to 1400 de grees C, respectively which yielded an activation energy of 370 +/- 20 kJ/mol. The scale that forms was dense. adhesive. resistant to therma l cyclings and layered. The outer layer was pure TiO2 (rutile), and th e inner lager consisted of mixture of SiO2 and TiO2. The results are c onsistent with a model in which growth of the oxide layer occurs by th e inward diffusion of oxygen ana the simultaneous outward diffusion of titanium and carbon. The presence of small volume fractions (approxim ate to 2%) of TiCx in Ti3SiC2 were found to have a deleterious effect on the oxidation kinetics.