Facile production of NaIO4-encapsulated nanoAl microsphere as green primary explosive and its thermodynamic research

NaIO4-encapsulated nanoAl nanothermites without additives were produced by a one-step spray-drying method under the temperature of 80 degrees C. This approach enables the NaIO4 matrix to completely cover Al nanoparticles, which are finally fabricated into NaIO4-encapsulated Al nanothermite. Differential scanning calorimetry revealed that the obtained NaIO4-encapsulated nanoAl released a heat of 1415.7 J g(-1), which is more than that of Al/CuO (1069 J g(-1)) nanothermite. The burning rate of the NaIO4-encapsulated nanoAl nanothermite was found to be almost six times higher than that of Al/CuO. At the same time, the new nanothermite system also demonstrated a high pressurization rate of 2.94 GPa s(-1) with a transient peak pressure of 5.66 MPa, as well as a rapid release of gases which was nearly three times higher than that of Al/CuO and two times higher than that of Al/NaIO4 (by physical mixing) and Al/Fe2O3 nanothermite. More importantly, the NaIO4-encapsulated nanoAl obtained by spray drying exhibits lower activity energy compared to Al/NaIO4 prepared by physically mixing method due to the higher degree of intermixing between fuel and oxidizer. The electrostatic sensitivity threshold of the NaIO4-encapsulated nanoAl is obviously higher than that of n-Al/CuO and Al/Fe2O3. In this paper, NaIO4-encapsulated nanoAl was used to directly initiate pentaerythritol tetranitrate, the initiating ability is greater than lead styphnate and close to lead azide. These results provide a feasible design scheme for replacing lead-based primary explosives because of the initiation power and process simplicity of thermites.