TiC–Cr3C2–WC–NiCr–Mo–C Cermet Plasma Coatings

Abstract

Two bulk cermets TiC-WC-Cr 3 C 2 -(Ni80Cr20)-Mo-2.8C after liquid-phase sintering at 1400°C for 1 h were used to manufacture powders for plasma spraying of coatings. The cermets were fabricated at a limited time of mechanical alloying at the mixing stage. Plasma coatings were sprayed on a setup with a nozzle attached to a plasmatron for local protection of the sprayed particles from the air atmosphere. The WC-Cr 3 C 2 -C content in the cermets provided compensation for carbon losses at all stages of coating production and the formation of an annular zone, the volume of which determines the increase in the TiC content in the coatings by 20% and the formation of additional carbides in the matrix. The microhardness of cermet at an initial carbide content of 60% was 15.26-16.83 GPa with a load on the indenter of 200 G and 20.91-24.68 GPa with a load on the indenter of 20 G, and the difference was explained by a scale factor. The contribution of the microhardness of carbides to the microhardness of cermet with an initial carbide content of 60% was estimated according to the rule of mixtures, proceeding from their volume fraction and microhardness of cermet under a load on the indenter of 20 G. In the initial powder for spraying, this contribution is high, 33.19 GPa, close to the hardness of TiC. The contribution of microhardness of carbides in the coating is lower, 28.09 GPa.