Oxidation of Ti3Al0.3Si0.7C2 Compounds at 900-1200 degrees C in Air

Abstract

(TiAl0.3Si0.7C2)-Al-3 compounds were synthesized via the powder metallurgical process, and oxidized isothermally and cyclically between 900 and 1200 degrees C in air. They had good thermal shock resistance, forming adherent oxide scales during cyclic oxidation. They oxidized to rutile-TiO2, alpha-(Al2O3), and amorphous SiO2, together with gaseous escape of carbon. The oxide scales that formed during isothermal and cyclical oxidation were similar in that an outer (TiO2, Al2O3)-mixed scale, a thin intermediate Al2O3 layer, and an inner (TiO2, SiO2)-mixed scale formed. The outer scale formed by the outward diffusion of Ti4+ and Al3+ ions. The intermediate scale formed by the outward diffusion of Al3+ ions. The inner scale formed by the inward diffusion of O2- ions. No selective oxidation occurred from the early oxidation period.