SYNTHESIS OF NANOSTRUCTURED SI3N4 SIC COMPOSITE POWDERS THROUGH HIGH-ENERGY REACTION MILLING/

In this study, synthesis of Si3N4/SiC nanocomposite powders through hi gh energy reaction milling was investigated. Graphite and silicon powd ers were used as the source of carbon and silicon, respectively, while the source of nitrogen was from either nitrogen or ammonia gases. Eff ects of milling conditions including the milling speed, milling time, the ball-to-powder weight ratio, the powder mixture composition and co oling conditions on the formation of Si3N4 and SiC were studied. It wa s found that milling silicon and graphite powders in an ammonia atmosp here followed by annealing in a nitrogen atmosphere is a viable approa ch 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 mixt ure composition, cooling conditions and the milling atmosphere. Explan ations of these effects were provided based on the fundamental process es that occurred during reaction milling. (C) 1998 Elsevier Science S. A. All rights reserved.