Microstructure and mechanical properties of Tribaloy T-800/WC composite coatings deposited on DZ125 directionally solidified alloy by laser cladding

Abstract

Addition of WC ceramic particles is an effective method to improve mechanical properties of coatings. To improve the wear properties of the T-800 alloy coating, Tribaloy T-800 and Tribaloy T-800/WC composite coatings are deposited on the DZ125 alloy by laser cladding. The influence mechanisms of WC contents (0 wt%, 5 wt%, 10 wt%) on the precipitation behavior of the Laves phase (Co₃Mo₂Si) and secondary phases, microhardness, and wear performance are systematically studied. The results show that the addition of WC promotes an increase in the Laves phase content and size reduction as well as an improvement in the dislocation density of the composite coating. As the WC content is increased from 0 wt% to 10 wt%, the Laves phase content increases from 30.5 % to 45.5 %, the average size reduces from 10.2 μm to 10.3 μm and the average KAM value rises from 0.58° to 0.81°. Moreover, after the addition of WC, additional WC phase, W₂C phase and Co₆Mo₆C phase appear in the composite coating, and the content of these secondary phases shows an upward trend with increasing WC content. The microhardness and wear properties of the composite coating are significantly improved by the evolution of the microstructure. The microhardness and wear properties of the composite coating are optimized when the WC content is 10 wt%. Compared to the coating without WC, the composite coating with 10 wt% WC increases the microhardness by 18.3 % and reduces the wear mass loss by 37.9 %.