Enhancing hot corrosion resistance of N-doping NiCoCr-based superalloy coatings fabricated by directed energy deposition in mixed molten salts

Here, a NiCoCr-based superalloy coating has been developed in ultra-supercritical environments. However, optimizing the coating composition to enhance the anti-corrosion performance remains a formidable challenge. This research introduced an innovative N-doping strategy to enhance the hot corrosion resistance of the coating by utilizing directed energy deposition. The hot corrosion behavior at 700 °C of the coating with N-doping reinforcement was investigated. Detailed characterizations of the microstructural evolution and corrosion products were conducted. The results showed that the improvement of hot corrosion resistance was attributed to the continuous protective film retained in the N-doping reinforced coating, which inhibited the inward diffusion of corrosive media to retard the chlorination and sulfuration reaction. This work provides new insight into the design of corrosion-resistant superalloys and highlights the potential of N-doping superalloy coating in extreme environments.