Effect of heat treatment on microstructure and mechanical properties of cold sprayed Ti coatings with relatively large powder particles

In this study, the effect of post-spray heat treatment on the microstructure, microhardness, and adhesive strength of the cold-sprayed Ti coating was investigated. It was found that a thick and relatively porous Ti coating was deposited by cold spraying. The coating surface layer presented a more porous structure. The microhardness of the as-sprayed Ti coating was slightly higher compared to pure Ti bulk, owing to the work hardening effect during deposition. After annealing at 850°C for 4 h under vacuum condition, the Ti coating also presented a porous structure with more uniformly distributed small pores. A metallurgical bonding between the deposited particles was formed through annealing treatment. The adhesive strength of coating was significantly improved after annealing. The microhardness of the annealed Ti coating was also increased.