Oxidation Behavior of MoSi2 and MoSi2-SiC Coatings Prepared by Plasma Spraying Technology

Atmospheric plasma spraying technique has been employed to fabricate coatings of MoSi₂ and MoSi₂ composites reinforced with 10, 20 and 30 vol.% SiC particles. MoSi₂ and MoSi₂-SiC powders synthesized by mechanically activated reactive synthesis route. Their oxidation behavior was examined at low temperature (500 °C) and high temperature (1000 °C). The microstructural characteristics and phase identification of the coatings before and after oxidation were examined by X-ray diffraction and scanning electron microscopy with qualitative energy-dispersive spectroscopy. The results exhibited that the incorporation of SiC reinforcements in the MoSi₂ matrix leads to enhanced oxidation resistance at 500 °C and effectively restrained the pest oxidation of MoSi₂. However at 1000 °C oxidation resistance of MoSi₂ is similar to MoSi₂-20%vol. SiC and showed better oxidation resistant behavior compared with the other coatings. The formation of protective SiO₂ layer at temperatures above 1000 °C provides good oxidation resistance for use at high temperatures.