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

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/cm2 on exposure at 500 °C for 840 h and 20 mg/cm2 on holding at 900 °C 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/cm2 at 500 °C for 840 h and 7 mg/cm2 at 900 °C 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 MoSi2 can be suppressed by electro-thermal explosion ultrahigh speed spraying technology and alloying Al.