Effect of different powers on microstructure evolution and corrosion behavior of 5SiC-Ni60 coatings by directed energy deposition

[Display omitted] •The effect of power variation on microstructure, phase-microhardness correlation, and corrosion resistance mechanisms.•The mapping relationship between phase reinforcement mechanisms and microhardness region features.•The 3000 W coating demonstrates the best corrosion resistance by PDP and EIS.•The passivation films including NiO, Fe2O3, Fe3O4, Cr2O3, and SiO2 effectively inhibit corrosion damage. The microstructural evolution and corrosion behavior of directed energy deposition (DED) additive manufactured 5SiC-Ni60 composite coatings are investigated, elucidating the impact of fluctuations in power on the coating. The experiment reveals the microstructural characteristics, eutectic evolution, phase-microhardness correlation, and corrosion resistance mechanisms, all influenced by power variation as a crucial factor. Utilizing SEM, EDS, XRD, PDP, EIS, and XPS, the mapping relationship between microstructure reinforcement mechanisms, microhardness region features, corrosion behavior formation mechanisms, and power variation is clarified. The optimal laser power is determined to be 3000 W, facilitating the formation of a dense passivation film, efficiently reducing corrosion contact area and enhancing corrosion resistance. The chemical composition of the passivation film is revealed through XPS. Furthermore, utilizing polarization characteristics, impedance analysis, and corrosion morphology as focal points of discussion, the pitting defects on the corroded surface are explained. Consequently, achieving corrosion protection for the composite coating requires intervention with appropriate power parameters, providing valuable insights for enhancing corrosion resistance based on process parameters.