STRUCTURE AND CHEMICAL-REACTIVITY OF BALL-MILLED GRAPHITE

Nanostructured carbon powders are prepared from graphite powder in a p lanetary mill using WC, stainless steel, and agate milling tools. The evolution of microstructure and chemical reactivity is studied by X-ra y diffraction and combustion methods,, respectively. The specific surf ace area of milled samples is determined by BET measurement and the im purity content is estimated by spark source mass spectroscopy There is no monotonous relationship between reactivity and specific surface ar ea of particles and agglomerations of particles. In contrast to impuri ty contents, distortion of atomic short- and medium-range order is sho wn to be essential for the observed enhancement of chemical reactivity . A statistical model for the milling process is formulated and used t o discuss the experimental data. As a result, an expression for the de pendence of combustion temperature on milling time is proposed.