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The oxidation behavior of molybdenum disilicide (MoSi2) powders at 400, 500, and 600oC for 12 h in air were investi- gated by using X-ray diffraction (XRD) and transmission electron microscopic (TEM) techniques. Significant changes were observed in volume, mass, and color. Especially at 500oC, the volume expansion was found to be as high as 7-8 times, the color changed from black to yellow-white, and the mass gain was about 169.34% after 8 h, with SiO2 and MoO3 as main reaction products. The gains in volume and mass were less at 400 and 600oC compared with those at 500oC, probably due to the less reaction rate at 400oC and the formation of silica glass scale at 600oC, which would protect the matrix and restrain the diffusion of oxygen and molybdenum. Thus, the accelerated oxidation behavior of MoSi2 powder appeared at 500oC and the volume expansion was the sign of accelerated oxida- tion.
The oxidation behavior of molybdenum disilicide (MoSi2) powders at 400, 500, and 600 ° C for 12 h in air was instilated by using X-ray diffraction (XRD) and transmission electron microscopic (TEM) techniques. Significant changes were observed in volume Especially at 500oC, the volume expansion was found to be as high as 7-8 times, the color changed from black to yellow-white, and the mass gain was about 169.34% after 8 h, with SiO2 and MoO3 as main reaction products. The gains in volume and mass were less at 400 and 600oC compared with those at 500oC, probably due to the less reaction rate at 400oC and the formation of silica glass scale at 600oC, which would protect the matrix and restrain The diffusion of oxygen and molybdenum. Thus, the accelerated oxidation behavior of MoSi2 powder was at 500oC and the volume expansion was the sign of accelerated oxida- tion.