Preparation of surface coating on copper alloy by laser remelting Ni plating coating composite process

Electroplated nickel coating was first deposited on the surface of CuCrZr alloy and then remelted by laser to obtain a new metallurgical coating with reliable interface and metallurgical bond. The microstructure and microhardness of laser remelting coating, and interfacial characteristics were investigated by using X ray diffraction and scanning electronmicroscopy equipped with X-ray energy dispersive microanalysis(EDX), as well as microhardness tester. The results indicated that a laser cladding coating metallurgically combined with copper substrate was obtained after 0.4 mm thick Ni coating was remelted by 4 200 W diode laser at room temperature with scanning speed of 10 mm/s. The absence of defects in the remelting coating with fine and compact structure could be observed. (Ni,Cu) solid solution phase was formed after the Ni plating composed of γ-Ni was remelted. The microhardness uniformly distributed across the section of the coating with the average value of 135 HV0.05, slightly higher than that of the copper substrate(about 125 HV0.05). The matching of the composition and hardness between the new coating and the copper matrix was the basis for ensuring good interfacial solubility and reliable metallurgical bonding.