A comparative study of MoSi2 coatings manufactured by atmospheric and vacuum plasma spray processes

In this work, MoSi2 coatings were manufactured by atmospheric plasma spraying (APS) and vacuum plasma spraying (VPS) technologies, respectively. Phase composition and microstructure of the coatings were characterized by X-ray diffraction and scanning electron microscopy. Microhardness, void and oxygen content of the coatings were also determined. Oxidation behavior of the coatings at high temperature was examined. The results showed that the surface of VPS-MoSi2 coating was dense and homogeneous. However, there were many microcracks formed on the surface of APS-MoSi2 coating. The VPS-MoSi2 coating also had lower void and oxygen contents, higher Vickers hardness compared with those of APS-MoSi2 coating. Besides, oxidation resistance of the VPS-MoSi2 coating was better than that of APS-MoSi2 at 1500 °C.