Synthesis and analysis of reactive nanocomposites prepared by arrested reactive milling

Different types of reactive nanocomposites have been synthesized by Arrested Reactive Milling (ARM). The technical approach was to increase the interface area available for heterogeneous reaction between solid fuel and oxidizer components. Using aluminum as the main fuel and different metal oxides as oxidizers, highly energetic reactive nanocomposites with different degrees of structural refinement were synthesized. Specifically, stoichiometric Al-MoO3, Al-CuO, and Al-NaNO3 material systems were studied in detail. The correlation of heterogeneous exothermic reactions occurring in the nanocomposite powders upon their heating at low rates and ignition events observed for the same powders heated rapidly was of interest. Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and heated filament ignition experiments were used to quantify the ignition kinetics and related reaction mechanisms. Fuel rich Al-MoO3 nanocomposites were also synthesized using ARM. Optimum composition and milling parameters were identified for fuel-rich compositions. Analysis of exothermic reactions in Al-MoO3 system showed that kinetics of such reactions could not be determined by isoconversion processing and respective activation energies could not be meaningfully found as functions of reaction progress. Instead, detailed DSC measurements at different heating rates are required to enable one in developing a multi-step kinetic model to describe such reactions adequately