Oxidation inhibition of γ-TiAl alloy at 900 °C by inorganic silicate composite coatings

• The γ-TiAl alloy exhibited poor oxidation resistance in air at 900 °C.
• An inorganic silicate coating was prepared by air spraying process on γ-TiAl alloy.
• The silicate coatings markedly improved the oxidation resistance of the alloy.
• The coatings have a sufficient thermal shock resistance.
• A continuous and compact Al2O3 layer was found under the coatings.

Inorganic silicate composite coatings on γ-TiAl were fabricated by air spraying. The oxidation behaviour of the alloy was investigated at 900 °C. The results indicated that rapid oxidation occurred in the γ-TiAl, and multilayered non-protective TiO2 and Al2O3 scales formed. For coated γ-TiAl alloy, the oxidation was markedly inhibited; a thin Al2O3 layer was detected, which improved the oxidation resistance of the alloy. The low oxygen partial pressure at the interface of the coatings and the alloy promotes the preferentially oxidation of Al in the γ-TiAl substrate, and the outward diffusion of Ti to form TiO2 was retarded.