Influence of Silicon and Chromium on the Na2SO4-Induced Hot Corrosion Behavior of Titanium Alloys

Titanium alloys are widely used as construction materials in the aerospace and automotive industries. They have many advantages but also have limitations related to their susceptibility to high-temperature oxidation and hot corrosion. Many efforts to increase the lifetime of components made of titanium alloys have been reported in the literature; the most promising ones involve the deposition of coatings. The present paper is focused on the development of coatings containing chromium and silicon, and their further evaluation in hot corrosion tests. It was proved that the Cr-Si coatings were more effective than Si coatings alone in protecting the titanium alloys against Na2SO4-induced hot corrosion at 800 & DEG;C. The enhanced corrosion resistance was attributed to the preferential formation of a thick and continuous SiO2 layer on the surface and-in the case of titanium aluminide alloy-the growth of an Al2O3-rich inner layer of the scale, promoted by chromium.