Effects of Y2O3 on the microstructure and wear resistance of WC/Ni composite coatings fabricated by plasma transferred arc

Abstract

The present study envisaged the WC-reinforced nickel composite coatings prepared on the surface of 4145H steel using the plasma transferred arc (PTA) method. The effects of different content of Y2O3 on the microscopic morphology, phase composition, micro-hardness and wear behavior were investigated by scanning electron microscopy (SEM) with an energy-dispersive spectrometer (EDS), X-ray diffraction (XRD), micro-hardness test and wear experiments. The deposited coatings consisted of WC-reinforced Ni59 composite coatings with the addition of 0 wt%, 0.5 wt% and 1 wt% Y2O3. Microstructural observation showed that the addition of 0.5 wt% Y2O3 had a better improvement on the coarse dendrites and the grain refinement. The main phase composition of the composite coatings was γ-Ni, FeNi3 solid solution, γ(Fe, Ni) eutectic phase, and the hard phase of WC, W2C. The cladding layer added with 0.5 wt% Y2 O3 was preferable over the Y2O3-free coating, as the microhardness was improved from 500 HV to 800 HV with a slight fluctuation of values. The coating with 0.5 wt% Y2O3 offered an excellent wear resistance to the extrusion and cracks for the uniformity of organizational structure compared with the substrate and the other two coatings. Furthermore, the results of weightlessness and coefficient of friction proved the positive effect of the rare earth Y2O3 on the wear resistance.