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

•A SiO2–Al2O3–glass coating was prepared by air spraying and following firing.•The coating decreased the oxidation rate of Ti–6Al–4V alloy at 800 °C and 900 °C.•The coating exhibited good resistance to cyclic oxidation and thermal shock.•Bilayer structure (Ti5Si3/Ti3Al) was observed at the coating/alloy interface.•A thin Al2O3 rich layer formed beneath the SiO2–Al2O3–glass coating at 900 °C.

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.