The oxidation behavior and interfacial reaction between SiO2 coating and Ti45Al8.5Nb alloy

In this study, SiO2 coating was electrodeposited on Ti45Al8.5Nb alloy to enhance its oxidation resistance at 900 °C. The focus was on the interaction between SiO2 coating and the alloy substrate, and specifically, the role of the Nb element in this context. The formation of a SiO2/(Ti, Nb)O2/Ti5Si3 + Al2O3 three-layer oxide scale significantly inhibits the inward diffusion of oxygen. Beyond the characteristic Ti5Si3 + Al2O3 layer at the interface, the Nb2Al phase embedded within Ti5Si3 was observed. Concurrently, the presence of a (Ti, Nb)O2 layer was confirmed. The relationship between the coating thickness and oxidation resistance was also investigated. It was found that the thickness of the SiO2 coating affects the density of the oxide scale and the inward diffusion rate of oxygen. Moreover, due to the good adhesion to the substrate, the derived oxide scale exhibited good anti-peeling performance when subjected to a cyclic oxidation test.