Preparing, Tuning and Characterizing Spherical Composite Powders of Reactive Materials

It was recently discovered that spherical composite powders with attractive mechanical and chemical properties can be prepared using emulsion-assisted milling. During milling, starting powders are simultaneously being refined, mixed, and packed inside droplets in the emulsion. In the produced powders, each particle is a spherical compact combining the starting material components mixed on submicron scale. The powders typically have narrow size distributions reflecting the size of droplets in the emulsion. Powders also have certain porosity. Both porosity and size can be controlled by the milling conditions. The emulsion-assisted milling was found to be a versatile material processing technique effective for making composite spherical powders of metals, ceramics, polymers and mixes thereof. Recent progress in preparation of such powders will be reviewed considering both metal-metal and metal-oxidizer compositions. Correlations between milling process parameters and morphological features of the produced powders will be considered. Separately, correlations will be explored between the powder’s morphological features and energetic performance. It will be shown that the powders with improved metrics characterizing their sphericity also have a better mixing between components that leads to their enhanced reactivity.