Multifunctional energetic structural materials (MESMs) are a new class of energetic materials, which release energy due to exothermic chemical reactions initiated under shock loading conditions. In order to analyze the impact-initiated process of MESMs, a quasi-sealed test chamber, which was originally developed by Ames [“Vented chamber calorimetry for impact-initiated energetic materials,” in AIAA (American Institute of Aeronautics and Astronautics, 2005), p. 279], is used to study on shock-induced chemical reaction characters at various impact velocities. The impact initiated experiments are involving two typical MESMs, Al/PTFE (polytetrafluoroethylene), W/Zr and inert 2024 Al fragment. The video frames recorded from reactive and inert material impact events have shown the process of late-time after burn phenomena. The total pressure and shock wave reflection at the wall of the test chamber are measured using high frequency gauges. The quasi-pressures inside the test chamber, which is fitting from the total pressure curves, are used to determine the impact initiated reaction efficiencies of MESMs at different impact velocities. A thermochemical model for shock-induced reactions, in which the reaction efficiency is considered, is validated against the experimental data from impact initiation. The results show that the impact velocity plays a significant role in chemical reaction and the energy release characteristics of MESMs. The theoretical calculations correlate reasonably well to the corresponding experimental results, which can be used to predict the reaction results of MESMs over a wide range of pressure satisfactorily.
25 October 2016 in The Journal of Physical Chemistry C
Multifunctional energetic structural materials (MESMs) are a new class of energetic materials which release energy due to exothermic chemical reactions initiated under shock loading conditions. In order to analyze shock-induced chemical reactions (SICR) for MESMs, theoretical models have been developed to calculate the Hugoniot data which include the heat released by shock temperature controlled reactions. The temperature rise of porous materials due to shock compression is first calculated using a constant volume and pressure adjustment. Then the Arrhenius reaction rate and Avrami-Erofeev kinetic models are used to calculate the extent of reaction of MESMs under shock compression. Thermochemical models for shock-induced reactions, in which the reaction efficiency is considered, are given by combining the shock temperature rise with the chemical reaction kinetics. The Hugoniot relations and temperatures are calculated by using the proposed method. The models developed have been validated against the experimental SICR data involving Fe2O3/Al, Al/Ni, and Ti/Ni mixtures. It has been shown that the theoretical calculations correlate reasonably well with the corresponding experimental and simulation results. The models presented can be used to predict the reaction results of MESMs over a wide range of pressure satisfactorily.