Preparation of TiC+(Al_2O_3/TiC)+Al_2O_3 Composite Coating by Plasma Spraying

The TiC+mixture(TiC/Al2O3)+Al2O3 composite coating was deposited on martensitic steels by atmospheric plasma spray-ing.The thermal shock resistance of the coating was evaluated at different temperatures.The morphologies of the coating before and after heat treatment were investigated.The corrosion resistance of the coating was analyzed by electrochemical technology.The re-sults show that this TiC+(Al2O3/TiC)+Al2O3 coating exhibits a high thermal shock resistance and a significant self-healing ability.The thermal shock cycle times of the coating at 800,700,600 ℃ and 500 ℃ were 157,125,95 and 83,respectively.After thermal oxida-tion at 600 ℃ for 30 h,the porosity of the coating was decreased by 90%,while the corrosion resistance of the coating increased by one order of magnitude.The energy dispersive X-ray analysis showed that,the oxidation products of TiC in the coating could fill in and seal the pores and crack in the coating.