Microstructure and oxidation resistance of Mo-Si and Mo-Si-Al alloy coatings prepared by electro-thermal explosion ultrahigh speed spraying

摘要

Mo-Si and Mo-Si-Al alloy coatings were synthesized on the surface of nickel-based superalloy substrate using electro-thermal explosion ultrahigh speed spraying technology. The coatings have dense microstructure with submicrometer size grains. The microhardness of the coatings is in the range of 1100-1350 HV. The weight loss of Mo-Si alloy coatings is found to be 2 mg/cm~2 on exposure at 500 ℃ for 840 h and 20 mg/cm~2 on holding at 900 ℃ for 360 h, respectively. However, Al alloyed in Mo-Si coatings obviously slows down the oxidation at high temperature. The weight loss of Mo-Si-Al alloy coatings is only 0.5 mg/cm~2 at 500 ℃ for 840 h and 7 mg/cm~2 at 900 ℃ for 360 h, respectively. The weight loss ratio of Mo-Si-Al alloy coatings decreases about 70% comparing to that of Mo-Si alloy coatings. The pest disintegration of the MoSi_2 can be suppressed by electro-thermal explosion ultrahigh speed spraying technology and alloying Al.