Effect of Energy Density on the Microstructure and Wear Resistance of Nickel-Based WC Coatings by Laser Cladding of Preset Zr702 Alloy Plates

Abstract

This study aimed to evaluate the microstructure and wear resistance of laser cladding coatings with different energy densities in the case of a preset 0.5 mm thick Zr702 alloy plate to determine the specific present form of Zr elements and the optimal laser energy density. Thereby, microscopic characterization and performance tests were carried out by the microhardness tester, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and tribometer. The results showed that, at different energy densities, the Zr elements in the coating were mainly in the form of ZrC and (Zr,W)C, which are hard particles with high wear resistance, and diffusely distributed in the coating to have second-phase-strengthening effects. Moreover, when the energy density was 28.3 J/mm2, the coating was well fused and had the highest microhardness of 936.4 HV0.2. The wear rate of the coating was the lowest at 90.8 μm3/(m·N). The wear was characterized by hard particle spalling and abrasive wear.