Investigation Of Organization Structure And Property Of High-aluminum Copper Alloy Coating Optimized At Interface By Ni60

To overcome the problems of uneven microstructure and imbalance elements distribution at the interface fusion zone of non-self-fluxing high aluminum bronze alloy coating, the gradient coatings of Ni60/High Aluminum Bronze was prepared by supersonic plasma spraying and remelting. Ni60/High Aluminum Bronze layer was prepared using SPAS on45#steel substrate, then, it was made the remelting treatment by high induction heating. The coating’s surface, fracture surface, the morphology of interface microstructure, element diffusion and performance of the samples was analyzed by optical metallographic microscope, X-ray diffraction instrument, spectroscopy equipment, scanning electron microscopy (SEM), electron probe microanalysis instrument (EPMA), macro Rockwell, micro hardness tester and universal testing machine. The coating’s phase composition and dense degree (porosity) of the samples were analyzed using Jade6.0, Image-pro plus5.0, Oringin8.0.The analysis results indicate that the high-aluminum coating surface shows a reticulate structure feature by SPAS. The main phases of the coating surface are a-Cu, CU9Al4and AlFe3. However, the reticulate structure feature has disappeared and the pore and oxide inclusion has been lessened after induction remelting. The structure of the coating after remelting becomes tightly dense, meaning while, the coating after remelting product the new phase Fe3Ni2and AlNi3, which are the new strengthening phases. The porosity of coating is6.26%by SAPS, however, the porosity of coating reduced to4.18%after induction remelting. So, the density of the coating has improved.The analysis results on the coating interface after SAPS indicates that the boundary of matrix, Ni60interlayer and high aluminum bronze layer is distinct, and the element content has showed mutation at the interface. While after induction remelting, a firm metallurgical combination is formed, and the elements show continuous gradient changes.The microhardness of coating surface has increased and been more stability after induction remelting than that of the samples by SAPS. This phenomenon indicates that the microstructure of the coating has become more uniform after induction remelting. However, the macro-hardness of the coating after induction remelting is lower than that of the sample by SAPS, which may be the reason of the grain growth, element diffusion and phase structure transformation. The bonding strength of coating interface is31.420MPa by SAPS, while it increased to92.603MPa after induction remelting. The prominent promotion of bonding strength links to the reason of the bonding mechanism transformation that from mechanical adhesion to metallurgical bonding.