Preparation of inorganic ceramic coatings on γ-TiAl alloys

With the development of aviation and aerospace engineering, transportation systems, chemical and thermal，high-temperature resistant coatings was widely concerned. Phosphate coating was a high-temperature inorganic coating. The water-soluble phosphate was its based material. The advantage of the phosphate coating shows many characters such as strong adhesion, good heat resistance, low cost, non-flammable, non-explosive, and so on[1]. Ceramic coatings possessed attractive properties because these kinds of materials have good thermal and chemical stability. Recently several ceramic coatings have been applied to TiAl alloy, such as Si₃N₄[2], SiO₂[3], Al₂O₃[4] and glass-ceramic coatings[5]. However, the coating’s brittleness and mis-match of coefficients of thermal expansion could be a problem leading to cracking and spalling.

In this paper, the main work that has been done including: (1) the preparation of phosphate ceramics high-temperature coating on the γ-TiAl substrate; (2) the thermal shock resistance, high-temperature oxidation and cyclic oxidation performance of the coating were studied;（3） the analysis of the coating were conducted by SEM, EDS, XRD, Chemical Analysis and so on.