Influence of annealing temperature on the structure and properties of Ti₃AlC₂ coatings by FCVA method

As a cermet compound, Ti₃AlC₂ phase has broad application prospects in aerospace and marine fields due to its excellent properties. In this paper, Ti₃AlC₂ coatings were prepared by a two-step method of FCVA deposition and post-annealing, and the influence of annealing temperature on the microstructure, mechanical properties and corrosion resistance of Ti₃AlC₂ coatings was systematically studied. The results exhibited that the phase composition and crystallinity of the coatings depended on the annealing temperature. When the temperature was 600 °C, the coating contained a small amount of Ti₃AlC₂ and Ti_xAl_y with low crystallinity. As increasing the temperature to 800 °C, the phase in the coating was dominated by Ti₃AlC₂ with some TiC and Al₄C₃. Continuing to increase the temperature to 1000 °C, the phase structure of the coating gradually changed from Ti₃AlC₂ phase to TiC phase. In addition, the annealing temperature also had a significant effect on the mechanical and electrochemical properties of the coatings. As the temperature increased from 600 °C to 1000 °C, the hardness of the coating gradually increased, and the H/E value first increased and then decreased. Besides, the corrosion resistance of the Ti₃AlC₂ coatings increased first and then decreased with the increase of temperature, and the coating showed the best corrosion resistance when annealed at 800 °C.