Atmospheric Plasma Spraying of SiC Particle-Reinforced MoSi2 Prepared by Mechanically Activated Reactive Synthesis

In this study, MoSi₂–SiC composites powders containing 10, 20 and 30% vol. SiC contents were synthesized by mechanical alloying and heat treatment of powders mixtures of Mo, Si and SiC, as a feedstock for thermal spraying. Agglomeration process was employed for suitably of grain size and flow rate of composite powders for using in thermal spraying process. Atmospheric plasma spraying technique has been used to deposit the agglomerated powders of MoSi₂-SiC composite under inert conditions onto a plain carbon steel substrate. Phase identification and microstructural characteristics of the powders and coatings were evaluated by X-ray diffraction, scanning electron microscopy and qualitative energy-dispersive spectroscopy. Microhardness, roughness, bonding strength and porosity of coating were also measured. Microstructure of the plasma sprayed coating consists of α and β- MoSi₂, SiC, Mo₅Si₃ and a small amount of SiO₂ phases. It can be concluded that mechanically activated reactive synthesis with agglomeration is an effective method for the preparation of high melting-point refractory compounds for using in plasma spraying process.