Synthesis of nanocrystalline SiC at ambient temperature through high energy reaction milling

This study investigated the in-situ synthesis of nanosized crystalline SiC powders at room temperature through high energy ball milling of elemental silicon and carbon mixtures. Milling conditions including the mill design, the milling speed, the milling time and the ball-to-powder weight ratio (i.e. the charge ratio) necessary for the in-situ synthesis were studied. It was found that uniform formation of nanosized crystalline SiC powders within the powder charge could be achieved with a correctly designed attritor and the contamination could be minimized with proper selections of milling conditions. The crystalline beta-SiC powders synthesized were themselves in nanosize scale, quite different from many previous studies which have shown that it is the internal grain structure of milled powders that is the ''nanocrystalline'' component of the powders (typically 5 - 20 nm), while the powders are themselves typically 0.1 mu m to > 1 mu m in size. Furthermore, it was found that the product structures generated by high energy reaction milling depended strongly on the milling speed, the charge ratio and the milling time. Copyright (C) 1996 Acta Metallurgica Inc.