Electrochemical study on the hot corrosion behavior of Ni16Cr13Co4Mo alloy in molten NaCl-KCl and NaCl-KCl-Na2SO4

The hot corrosion behaviors of a novel Ni16Cr13Co4Mo alloy were investigated in molten NaCl-KCl and NaCl-KCl-Na2SO4 through electrochemical measurements, GIXRD and EPMA. The results showed that the overall corrosion was controlled by the diffusion process. Hot corrosion process was promoted by the increases in temperature and presence of Na2SO4. In molten NaCl-KCl, the corrosion layer was mainly composed of Cr2O3, and exhibited p-type semiconductive properties. In molten NaCl-KCl-Na2SO4, intergranular corrosion was observed and the corrosion layer consisted of a Cr2O3 outer layer (p-type) and a TiO2-Al2O3 inner layer (n-type). The relationship between the electrochemical mechanism and hot corrosion was discussed.