Effect of parameters of emulsion-assisted milling on morphology and reactivity of a spherical thermite powder

Spherical reactive composite powders with narrow size distributions are desired as feedstocks for printable reactive inks. Emulsion-assisted milling (EAM) yields such powders for a range of materials. Earlier work established certain relationships between the EAM process parameters and material properties for one material system. This study aims to expand the applicability of such relations to different materials. A stoichiometric Al·Fe₂O₃ composite thermite powder was prepared by EAM. When the EAM process parameters are not optimized, the product contains both spherical and irregularly shaped composite particles. Optical microscopy and image analysis served to separate the EAM-produced thermite particles into spherical and irregular classes. Thermal analysis was used to quantify the reactivity of the prepared powders. The morphological characteristics of the powders, their composition (from XRD), and their reactivity descriptors were correlated with both the EAM process parameters and the powders’ quality metrics. At least some of the process-property correlations for EAM apply similarly to different materials. Correlations between the powder morphology and its reactivity are indirect.