Oxidation and hot corrosion behavior of Ti2AlNb-based alloy with and without enamel coating at 800 ℃
(1.辽宁省沈阳市科学院金属研究所金属腐蚀与防护国家重点实验室
2.State Key Laboratory for Corrosion and Protection, Institute of Metal Research,Chinese Academy of Sciences, Shenyang 110016, China)
2.State Key Laboratory for Corrosion and Protection, Institute of Metal Research,Chinese Academy of Sciences, Shenyang 110016, China)
Abstract: 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.
Key words: Ti2AlNb; enamel coating; oxidation; hot corrosion