Characterization of microstructure and oxidation resistance of Y modified silicide composite coating on Mo-Cr-W-Al-Ti substrate

Y modified silicide composite coating (Si-Y coating) was prepared on Mo-Cr-W-Al-Ti substrate by Si and Y2O3 co-deposition at 1200 & DEG;C for 20 h. The oxidation resistance of the coating was studied by analyzing the phase constituents and microstructure. A double layer coating has been observed: a thick outer layer consisting of (Mo, X)Si-2, (Cr, X)Si-2 and Al2O3, and a thin inner layer of (Mo, X)(5)Si-3, (Cr, X)(5)Si-3, Al2O3. The Si-Y coating possessed better oxidation resistance under high temperature conditions than the unmodified one, the mass gain of 5.97 mg/cm(2) after 18 cycles of oxidation at 1300 & DEG;C in air for 150 h for the former and the beginning of weight loss after 18 h under the same condition for the latter. The dispersed Y2Ti2O7 contained in the compact SiO2 protective layer acts as a "skeleton " to improve the oxidation resistance of the Si-Y coating.