Synthesis of nanostructured Si3N4/SiC composite powders through high energy reaction milling

In this study, synthesis of Si3N4/SiC nanocomposite powders through high energy reaction milling was investigated. Graphite and silicon powders were used as the source of carbon and silicon, respectively, while the source of nitrogen was from either nitrogen or ammonia gases. Effects of milling conditions including the milling speed, milling time, the ball-to-powder weight ratio, the powder mixture composition and cooling conditions on the formation of Si3N4 and SiC were studied. It was found that milling silicon and graphite powders in an ammonia atmosphere followed by annealing in a nitrogen atmosphere is a viable approach for preparing nanostructured Si3N4/SiC composite powders. Further, the formation of Si3N4 and SiC was found to be affected by the milling speed, milling time, the ball-to-powder weight ratio, the powder mixture composition, cooling conditions and the milling atmosphere. Explanations of these effects were provided based on the fundamental processes that occurred during reaction milling.