Sulfate-Based Nanothermite: A Green Substitute of Primary Explosive Containing Lead

Currently, synthesizing a “green” alternative for primary explosives has become a new challenge for researchers, therefore the feasibility of sulfate-based nanothermite n-Al/CuSO4·5H2O was investigated in this work. n-Al/CuSO4·5H2O was prepared by electrostatic spraying (ES), which formed unified microspheres; CuSO4·5H2O particles were coated with n-Al particles. The reactivity was initially evaluated using thermogravimetry (TG) and differential scanning calorimetry (DSC), and the results show that the heat release of n-Al/CuSO4·5H2O (ES) is 1.6 kJ/g more than that of n-Al/CuSO4·5H2O (PM). A high-speed camera and ignition experiments in a confined bomb were used to assess the combustion performance of the two samples. Results show that n-Al/CuSO4·5H2O (ES) exhibited outstanding performance for flame, peak pressure, and pressurization rate. The combustion in the confined bomb experiment also demonstrates that a molar ratio up to 8:1 can be the optimum ratio for the reaction between the fuel and the oxidizer. To compare the performance of metallic oxide nanothermite, n-Al/CuO was prepared by physical mixing. The n-Al/CuSO4·5H2O nanothermite shows more gas release and it is safer than that of n-Al/CuO nanothermite, which was confirmed by the results of combustion in the confined bomb and electrostatic sensitivity experiments. Moreover, in this investigation n-Al/CuSO4·5H2O (ES) was used to directly initiate RDX which is a feasible design for replacing lead-based primary explosives.