Study of KCl-induced hot corrosion behavior of high velocity oxy-fuel sprayed NiCrAlY and NiCrBSi coatings deposited on 12CrMoV boiler steel at 700

The hot corrosion behavior of two kind of HVOF-sprayed NiCr-based coatings with different oxide-forming elements (such as Al and Si) was investigated and compared in the presence of KCl salt at 700 ℃. The results showed that the hot corrosion resistance of NiCrBSi coating was superior to that of NiCrAlY coating. NiCrAlY coating was seriously corroded and severe internal oxidation was produced along the splat boundaries, while the corrosion of NiCrBSi coating was relatively mild and the inner coating remained intact, which was ascribed to the denser structure and the generation of a SiO2 protective layer. [Display omitted] •NiCrBSi coating offered better corrosion resistance to KCl than NiCrAlY coating.•Chromia and alumina failed to resist the hot corrosion ingress in coating.•Alumina is difficult to form a protective oxide film at lower temperatures in KCl salt.•The continuous SiO2 layer effectively blocks the progress of activation oxidation.•SiO2-forming materials could be a promising material in alkali chloride salt.