Hot corrosion resistance activation energy of manganese-cobalt coated Crofer 22 APU steel

In this study, the pack cementation method was employed to coat manganese and cobalt onto Crofer 22 APU steel. Hot corrosion at 800°C and hot corrosion at different temperatures were applied to evaluate the activation energy. In each test, the coated samples demonstrated lower kp, indicating that the coating layer had acted as a mass barrier against the outward diffusion of cations (Cr) and inward diffusion of anions (Cl, S, O). The formation of MnCo2O4, CoFe2O4, CoCr2O4 and Co3O4 spinels, improved the hot corrosion resistance of Crofer 22 APU steel and it resulted to the lower hot corrosion activation energy of cobalt coated samples in comparison with the coated ones.