Evaluation of hot corrosion resistance of directionally solidified nickel-based superalloy

摘要

The turbine blades made of directionally solidified nickel-based superalloys are exposed to combination of high temperature and exhaust fumes, in which appear corrosion promoting elements like sulphur, sodium and vanadium (hot corrosion). Corrosion resistance of superalloys is mainly dependent on their structure and chemical composition. Therefore, it is important to be aware of the correlation between the hot corrosion and changes in chemical composition and morphology of a surface of the material. The following paper presents the influence of sulphur on the microstructure of directionally solidified nickel-based superalloy. The research was carried out in Na_2SO_4 environment at two temperatures of 850 ℃ and 900 ℃ (below and above the melting point of salt, 884℃). The results show scale morphology on material surface and changes in chemical composition of surface of nickel superalloy.