Effect of WC particle size on the microstructural evolution and wear resistance of laser cladding Inconel 718/WC-12Co composite coating

The Cr-Zr-Cu copper alloy is widely used to manufacture mold for continuous casting. The proper coating can avoid the mold's failure under the condition of a high-temperature and friction environment. Three kinds of Inconel 718/WC-12Co coatings (micro-, nano-, and micro-nano-WC particles) were prepared on the surface of the copper alloy by laser. The phases, microstructure, and elemental distribution of L1–L3 coatings were observed and analyzed by x-ray diffractometer, scanning electron microscope, and energy dispersive spectrometer. The properties of L1–L3 coatings were tested by a Vickers hardness tester and friction and wear testing machine. The results show that the main phases are γ-Ni, M3W3C, MC, W0.15Ni0.85, and W2C in the L1–L3 coatings. In the L1 coating, there is an obvious phenomenon of WC agglomeration. In the L2 coating, there are many columnar, dendritic compounds, and “fish-bone” crystals with small size due to the addition of nanoparticles. In the L3 coating, the structure is scattered due to the uneven distribution of compounds. The average values of L1–L3 coatings' microhardness are 709.6, 851.9, and 600.1 HV0.5, respectively. The L2 coating has the maximum average microhardness. When the experimental temperature is 400 °C during the friction and wear test, the wear rates of L1–L3 coatings are 3.29, 1.89, and 2.83 × 10−4 mm3 N−1 mm−1, respectively. The L2 coating has the minimum wear rate due to the smaller grain size, denier microstructure, and “fish-bone” structure.