Abstract
Metal hydrides are regarded as promising hydrogen-supplying fuel for energetic materials while CL-20 (Hexanitrohexaazaisowurtzitane) and FOX-7 (1,1-Diamino-2,2-dinitroethylene) are typical principal components commonly used in energetic materials. Hence, it is interesting to explore the interactions between them for development of new energetic systems. In this paper, the adsorption and decomposition of CL-20 or FOX-7 molecules on the MgH2 (110) crystal surface were investigated by employing the First-Principles. In total, 18 adsorption configurations for CL-20/MgH2 (110) and 12 adsorption configurations for FOX-7/MgH2 (110) were considered. The geometric parameters for the configurations, adsorption energies, charge transfer, density of states, and decomposition mechanism were obtained and analyzed. In most of the configurations, chemical adsorption will occur. Moreover, the orientation of the nitro-group in CL-20 or FOX-7 with regard to the MgH2 (110) surface plays an important role on whether and how the energetic molecule decomposes. The adsorption and decomposition of CL-20 or FOX-7 on MgH2 could be attributed to the strong charge transfer between Mg atoms in the first layer of MgH2 (110) surface and oxygen as well as nitrogen atoms in the nitro-group of CL-20 or FOX-7 molecules.
Highlights
With the development of hydrogen energy, various hydrogen storage materials emerge such as metal hydrides
The results show that 5% MgH2 can decrease the low and high peak temperatures by 35 °C and 44.2 °C during thermal decomposition of ammonium perchlorate (AP), respectively, and increase the apparent heat release of AP from 0.44 kJ × g−1 to 1.20 kJ × g−1, which indicates a remarkable catalytic effect of MgH2 on AP thermal decomposition
The results show that the addition of MgH2 makes the initial temperature of decomposition reduce greatly and the decomposition mechanism of the introduction of metal hydrides into propellants and explosives shows great advantages, the interaction mechanism between metal hydrides and energetic compounds remains unclear due to the huge diversity of both components, which is one key issue restricting the application of metal hydrides in energetic materials
Summary
With the development of hydrogen energy, various hydrogen storage materials emerge such as metal hydrides. Many current studies are focused on the effects of metal hydrides addition on the properties of energetic materials through experiments [11,12,13,29,30,31], which are costly and hazardous In this sense, the numerical simulation based on theoretical model provides a reasonable tool to study the interactions among various components in energetic materials. The interactions of two typical principal components in energetic materials, i.e., CL-20 and FOX-7, with magnesium hydride were studied by exploring the adsorption and decomposition properties of the energetic molecules on the MgH2 (110) surface. The adsorption configurations, adsorption energies, charge transfer, and density of states before and after the adsorption were calculated by First-Principles simulation, in hope of shedding light on how and why the concerning energetic molecules interact with MgH2 , as well as its significance in preparing for propellants with added metal hydrides
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