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 γ-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 °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 °C to 600 °C, and both showed the largest values at 400 °C. The abrasion mechanism was translated from the abrasive wear to the abrasive wear, adhesive wear, and oxidation wear.