Improved high-temperature oxidation resistance of TC4 alloy by electrodeposited SiO2 coating

Thickness controllable SiO2 coating was fabricated on TC4 alloy by electrodeposition. The oxidation behavior of TC4 alloy with SiO2 coating was studied at 700 °C. The effect of electrodeposition time on the coating thickness, morphology, and oxidation performance was studied. Results showed that with the increase of electrodeposition time, the thickness of the SiO2 coating almost linearly increased, while the oxidation resistance improved firstly and then decreased. During high-temperature oxidation, the SiO2 coating could react with the substrate and strengthen the interfacial structure. To further enhance the oxidation performance, before thermal exposure to air, the SiO2 coating protected TC4 alloy was sintered in argon. This resulted in the generation of a compact and glass-like oxide scale which could effectively prevent the inward diffusion of oxygen and the outward diffusion of titanium, therefore significantly enhancing the oxidation performance of TC4 alloy.