The influence of environmental processing conditions on the reactivity of aluminum with various oxidizing agents

摘要

The effect of environment on processing mixtures of aluminum (Al) with different oxidizers and resulting reactivity was investigated. Recently, processing liquid polarity was shown to significantly influence the reactivity of aluminum combined with fluoropolymers like polytetrafluoroethylene (PTFE). Specifically, processing mixtures of Al and PTFE using hexane (i.e., non-polar) as the carrier fluid, produced flame speeds of only 165 m/s while the same mixture processed in isopropanol (i.e., polar) resulted in flame speeds on the order of 460 m/s. The difference in reactivity was attributed to pre-ignition reaction (PIR) kinetics between the alumina passivation shell surrounding aluminum particles and fluorine. The PIR is enhanced by increased surface hydroxyl concentrations attributed to polar carrier fluids. This study extends the previous analysis toward assessing the influence of processing liquid on reactivity of aluminum with other oxidizing agents, specifically CuO and MoO_3. Results show no PIR kinetics associated with Al and a metal oxide (i.e., CuO and MoO_3) such that the influence of processing liquid polarity did not induce an appreciable difference in reactivity. The results from this study confirm that manipulating the surface of Al particles by growing the hydration layer through treatment in polar processing liquids is an approach for enhancing Al reactivity applicable to fluorine based oxidizers and does not extend to metal oxides that do not exhibit PIR kinetics.