Excellent hot-corrosion and thermal-shock resistance of metal-enamel composite coating on martensitic stainless steel enabled by interface engineering

Hot corrosion and thermal shock behaviors of nano-nickel enamel composite coatings on martensitic stainless steel at 650 °C were investigated, and compared with pure enamel coatings. Both enamel coating and composite coating can protect the steel from the corrosion of NaCl-Na2SO4 eutectic molten salt. However, the enamel coating suffers serious spallation during thermal cycles. Thermal shock resistance of enamel coating is largely improved by adding nano-nickel, as nickel particles not only hinder the rapid expansion of cracks through deflection and branching mechanism, but also act as repair capsules to build bridges for the viscous flow of enamel to heal crack.