Effect of CeO2 on the microstructure and microhardensss of laser-cladded Ni60 on 35CrMoV alloys.

ABSTRACT

In present work, the effect of CeO2 addition on the crack susceptibility, microstructure, phase composition, solute segregation and microhardness of Ni60 cladding layer was investigated. The coatings were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and microscopic vickers hardness tester. The results show that main phase composition of Ni60 cladding layer are Ni3Fe, Ni3V, Ni3B, Cr23C6, Fe5C2. The microhardness of the cladding layers from the surface to the substrate is gradually decreased with increasing depth of the cladding layer. With increasing addition of CeO2, the diffraction peak of XRD is shifted to the left, indicating the lattice distortion in the phases of the coating. Compared with other cladding layers with different contents of CeO2, the solute distribution of Ni60 cladding layer containing 4.0 % CeO2 is more uniform, and the cross-section structure is more compact and homogeneous. The results show that the addition of 4.0 % CeO2 can effectively inhibit the cracks and porosity, promote grain refinement, and improve the microstructure homogeneity in the Ni60 cladding layer.