Effect of Y2O3 addition on the microstructure and properties of Ni60 additives by micro-plasma cladding

Abstract

In this study, the effect of rare earth oxide Y2O3 dispersion particles on the wear resistance and high temperature oxidation performance of Ni60 cladding layer, prepared by micro-plasma cladding, were investigated in detail for the purpose of the additive manufacturing and repair. The results shown that the addition of rare earth oxide Y2O3 reduced the conductivity and thermal conductivity of the nickel-based powder, changing the surface tension of the nickel-based powder after melting and improving the wettability of the molten pool metal, which directly affected the weldability and molding parameters of the cladding layer. When the content of Y2O3 is 1%, the cladding layer was well formed, and the microstructure was mainly composed of cell dendrites and needle-like structures. Moreover, the addition of Y2O3 also changed the thermodynamic conditions of the nucleation growth of the cladding layer, reducing the size of the hard phase such as boron chromium compound, carbon chromium compound, and increasing the distribution concentration. When the Y2O3 content is less than or equal to 1%, the dispersion distribution of Y2O3 refined the microstructure of the cladding layer, decreasing the size of the precipitated phase. The dispersion strengthening enhanced the hardness of the cladding layer and improved wear resistance. The wear mechanism of Ni60 cladding layer was adhesive wear and minute abrasive wear. At 700 °C high temperature oxidation experiment, the oxidation kinetic curve was parabolic, and the cladding layer finally forming a continuous composite oxide film (Cr2O3, YCrO4, NiCrO3, FeCr2O4, SiO2). The presence of rare earth oxide Y2O3 reduced growth rate of oxide film and improved the high temperature oxidation resistance of the cladding layer.