Microstructure and Properties of Ni-Co Composite Cladding Coating on Mould Copper Plate

In this study, a Ni-Co composite coating was fabricated successively on a copper substrate by laser, and the microstructure and properties of the composite coating were studied. Our results show that the elements from Ni and Co alloy powder were uniformly distributed in the binding region, which obtained a good metallurgical bonding with the substrate. The microhardness of Co-based coatings was 646 HV_0.1, which was approximately 7.6 times greater than the hardness of Cu substrate. The Ni-based coating hardness was a little lower than that of the Co-based coating, which was approximately 7.0 times higher than the hardness of Cu substrate. The Co-based coating was comprised of reinforced phases, such as Co, Ni-Cr-Co-Mo, M₇C₃ and {Fe, Ni}. The wear volume of Co-based coatings was approximately 0.164 mm³ after the sliding wear test at 60 min, which was only 4% of the substrate's wear volume. Meanwhile, the heat shock resistance experiment was carried out at 800 °C for 75 times before the Ni-Co composite coating was peeled off. It was shown that this Ni-Co composite coating had good wear resistance and high temperature properties, which is helpful to improve the service life of a mould copper plate. It not only saves the economic cost of steel plants, but also improves the quality of slabs and products.