Oxidation and hot corrosion behavior of Ti2AlNb-based alloy with and without enamel coating at 800 ℃

The oxidation and hot corrosion behavior of Ti2AlNb-based alloy with and without enamel coating at 800 ℃ was investigated. The results indicated that Ti-22Al-25Nb alloy exhibited poor oxidation resistance at 800 ℃. The constitution of oxide scale had the effect on its oxidation rate. Because of the S and Cl accelerating the corrosion process, Ti-22Al-25Nb alloy suffered severe hot corrosion and exhibited very poor hot corrosion resistance. Enamel coating could remarkably improve the high temperature oxidation resistance of Ti-22Al-25Nb alloy because it had good chemical stability and matched thermal expansion coefficient with the substrate. In (Na,K)2SO4+NaCl molten salts at 800 ℃, chemical reactions between molten salts and enamel coating occurred and complicated products formed on the surface of the enamel coating; Cl- in the molten salts could penetrate through the coating and induced the substrate corrosion, but enamel coating still had good hot corrosion resistance.