Effect of CeO2 Addition on Grain Refinement and Mechanical Properties of Stellite-6 Coating Fabricated by Laser Cladding

To improve the wear resistance of the crankshaft, co-based coatings with different additions of CeO2 (0, 1, 2, 3, 4 wt%) were successfully prepared by laser-cladding technology on the surface of 42CrMo. The effects of CeO2 addition on the microstructure, microhardness, and wear properties of the coatings were investigated by scanning electron microscopy, energy dispersive spectrometry, x-ray diffraction, microhardness testing, and friction testing. The results show that CeO2 could obviously reduce the dilution rate of coating and avoid the elements in Stellite-6 powder being diluted into the substrate. CeO2 had little effect on the phase composition of the coating, while the coating was mainly composed of γ-Co, M23C6, and M7C3. With the addition of appropriate CeO2 content, it was found that CeO2 played a critical role in refining the grains in the coating, and reducing the residual stress in the coating, which reduced its crack sensitivity. CeO2 can strengthen the internal structure of the coating and improve its microhardness and wear resistance. Especially, while the content of CeO2 powder was 3 wt%, the wear rate was only one-half that of the pure Stellite-6 coating and the wear morphology was the smoothest. The optimal addition of CeO2 in the Stellite-6 coating was 3 wt%.