Microstructure and oxidation behavior of a SiC–Al2O3–glass composite coating on Ti–47Al–2Cr–2Nb alloy

• A SiC–Al2O3–glass coating was prepared by air spraying followed by firing.
• The composite coating decreased the oxidation rate of the Ti–47Al–2Cr–2Nb alloy.
• Reactions between coating and alloy were studied by SEM, EDS, XRD and EPMA.
• Z-phase (Ti5Al3O2), Ti5Si3 and Al2O3 formed at the coating/alloy interface.
• Oxidation of the SiC inclusions was observed in the outer part of the coating.

A SiC–Al2O3–glass composite coating was prepared on Ti–47Al–2Cr–2Nb alloy by a slurry made from aqueous solution of potassium silicate and powders of SiC and Al2O3. The oxidation behavior of the specimens was studied at 800 °C, 900 °C and 1000 °C. The composite coating prevented the inward diffusion of oxygen from air to the coating/alloy interface, therefore, decreasing the oxidation rate of the alloy remarkably. Besides, the composite coating exhibited good thermal cyclic resistance on Ti–47Al–2Cr–2Nb alloy. The microstructure changes of the composite coating, including oxidation of the SiC inclusions and the coating/alloy interfacial reaction, were investigated.