The Influence of Annealing on the Microstructure, Mechanical, and Tribological Properties of Cold-Sprayed (Cr3C2–Ni20Cr)–Ni25C Coatings

Improving the functionality and durability of working components, and consequently reducing production costs, became one of the main goals of scientists. Thermal modification of cold-sprayed composite coatings offered this opportunity. In this study, Cr 3 C 2 –NiCr–NiC coatings cold-sprayed on X6CrNiTi18-10 steel substrates annealed at two different durations (24 and 72 hours) and temperatures (500 °C and 800 °C) were investigated. Annealing the coatings under specific temperature and time conditions resulted in the formation of new oxide and carbide phases. Different conditions applied modified the coatings’ properties in various ways. Heat treatment for 24 hours at 500 °C did not cause changes in the coatings, whereas heating for the same time at 800 °C resulted in only slight changes in the microstructure and surface of the coatings. The coatings annealed for 72 hours at 500 °C have a 300 nm oxygen layer on the surface and have the highest microhardness (730 HV0.3), while those annealed at 800 °C show the lowest mass loss during the abrasive wear test. The annealed coatings showed a lower wear index ( e.g., 4.7·10 −6 m 3 /Nm at 800 °C, and 5.9·10 −6 m 3 /Nm at 500 °C) than the as-sprayed ones ( e.g., 19.1·10 −6 m 3 /Nm). The obtained results showed that annealing may be an effective heat treatment method, enhancing the mechanical and tribological properties of the coatings.