Microstructure and Properties of Sic Strengthened Laser Cladded Inconel625/Nb Coatings

Abstract

The In625/Nb/SiC composite coatings with SiC content ranging from 0 to 2.4 wt% were fabricated through the laser cladding technology. The microstructure of the coating was characterized at length and the properties of the coating were fully tested. Testing results revealed that the Nb promoted the formation of laves phase and elevated the performance of the coating, while there was segregation of Nb. The addition of SiC promoted the generation of M(Nb, Mo)C and Cr23C6 in the coating and improved the homogeneity of the microstructure. The microhardness distribution of the samples could be divided into four zones in order: substrate, heat affected zone, fusion zone and coatings. Similarly, the microhardness of the coatings gradually improved as the SiC content increased, and 2.4SiC coating obtained the highest microhardness, which was 58.2% above the substrate. The friction test results indicated that the increasing SiC had a constructive impact on the friction performance of the coatings, namely, the wear rate of the coatings was decreased over the substrate by 20.7%, 36.7%, 44.6%, 60.1% and 70.1% in order. The wear mechanism shifted from grievous adhesion, oxidation, and fatigue wear in the substrate to mild adhesion and oxidation wear in 2.4SiC coating. This work investigated SiC enhanced In625/Nb/SiC composite coatings and provided a new solution for repairing and improving the performance of In625.

Keywords: Laser cladding, In625, SiC content, performance, Microstructure.