Microstructure and high temperature tribological performance of Co-based laser cladded coatings reinforced with in-situ TiN-VC

Co-based laser cladded coatings reinforced with in-situ TiN-VC was prepared. The microstructure and high temperature tribological performance of the cladded coatings were researched. Results revealed that TiN and VC were identified in the cladded coatings with in-situ TiN-VC, besides gamma-Co and Cr23C6 phases. In-situ TiN and VC promoted the formation of lots of short rod-shaped dendritic crystals and equiaxed crystals, refining the microstructure. Compared with the Co-based cladded coatings, the microhardness of the cladded coatings with in-situ TiN-VC at 20 degrees C was improved by 30.0%, the mass loss was reduced by 51.3%, and the friction coefficient was obviously decreased. The mass loss and friction coefficient of the cladded coatings with in-situ TiN-VC were both initially decreased and subsequently increased as the temperature was increased from 20 degrees C to 600 degrees C, and both showed the largest values at 400 degrees C. The abrasion mechanism was translated from the abrasive wear to the abrasive wear, adhesive wear, and oxidation wear.