SiO2–Al2O3–glass composite coating on Ti–6Al–4V alloy: Oxidation and interfacial reaction behavior

A SiO₂–Al₂O₃–glass composite coating was prepared on Ti–6Al–4V alloy by air spraying and subsequent firing. The oxidation behavior of the specimens at 800 °C and 900 °C for 100 h was studied. The thermal shock resistance of the coating was tested by heating up to 900 °C and then quenching in water. The composite coating acted as an oxygen migration barrier and exhibited good resistance against high temperature oxidation, thermal shock, and oxygen permeation on the Ti–6Al–4V alloy. Coating/alloy interfacial reaction occurred, forming a Ti₅Si₃/Ti₃Al bilayer structure. A thin Al₂O₃ rich layer formed beneath the composite coating during oxidation at 900 °C.