Microstructure and anti-oxidation behavior of laser clad Ni–20Cr coating on molybdenum surface

A Ni–20Cr coating was deposited on a molybdenum substrate by laser cladding. The observation of the microstructure by SEM demonstrates that the coating is free of cracks and pores, and metallurgically bonded to the substrate. XRD and EDS analysis results show that some dilution occurs at the coating/substrate interface and that Mo combines with Ni–20Cr, to form a Ni–Cr–Mo alloy coating with slight oxidation. The oxidation behavior of the coating indicates that the laser clad Ni–20Cr coating can effectively prevent oxidation of molybdenum at 600 °C in air. The oxide scale formed on the coating surface by oxidation in air is composed of NiO, Cr2O3 and NiMoO4.