Characteristics Study on in-situ NbC Particles Reinforced Ni-based Alloy Composite Coating by Laser Cladding

Abstract

The in-situ synthesized NbC particles reinforced Ni-based alloy composite coating was successfully fabricated by laser cladding a precursor mixture with a mass percentage of 80%Ni-based alloy powder (Nb10 powder) and 20% Cr3C2 powder on Q235 steel substrate. Another composite coating was also produced by laser cladding using 100% Ni-based alloy powder as cladding material for comparison. X-ray diffraction (XRD), scanning electron microscopy(SEM), energy spectrum analysis(EDS), microhardness measurement and wear resistance test were performed on the cladding coating. The results show that Ni-based alloy composite cladding coatings are homogeneous and free from cracks, the cladding coating and the substrate exhibit excellent metallurgical bonding. The main phases of the composite coating were (Fe,Ni) solid solution, NbC and Cr23C6 reinforced phases. Abundant NbC particles can be uniformly formed via in-situ reaction between niobium and Cr3C2 in the molten pool during the laser cladding process, and they are commonly precipitated in three kinds of morphologies: granular, quadrilateral and petaloid shape. However, the comparative coating was only composed of (Fe,Ni) solid solution, without the formation of any carbides. The microhardness and wear resistance of composite coating of NbC particle reinforced composite cladding coating were improved significantly, the results indicate that the existence of NbC particles plays a crucial role in enhancing the performance of the cladding coating.