纳米RDX有序内嵌三维Al/CuO含能体系的可控构建及反应机制研究

Nanothermites are composed of nano-sized oxidizing agents and reducing agents. They show high volumetric energy densities and large chemical reaction rates. However, there is little gas production during the reaction, and thus the power to do work is insufficient. Explosives decompose to generate a lot of gaseous products, which can provide pressure compensation to the reaction zone of nanothermites. Therefore, the combination of explosives and nanothermites has become a hot research topic in recent years. It is found that synergistic effects arise when nanothermites and explosives are combined and the composites have great application potential in the areas of green primary explosives and energy source for miniature energetic devices. However, in previous studies, nanothermites and explosives were combined through randomly mixing, and thus limited by the randomness of the microscopic chemical composition, the mechanism responsible for the synergistic effects is unclear so far. In this proposal, from the perspective of interfacial reaction characteristics, based on the controllable construction of composite nanoenergetic materials in which nano RDX is orderly embedded into three-dimensional Al/CuO nanothermites, the energy-release characteristics of the composites will be thoroughly studied through chemical thermodynamics and kinetics analysis, and together with the in-depth analysis of the chemical reaction mechanism, the mechanism responsible for the synergistic effects will be revealed. The proposed study can provide theoretical and application foundations for the development of novel “nanothermites/explosives” composite nanoenergetic materials.

纳米铝热剂由纳米尺度的氧化剂与还原剂组成，具有高体积能量密度及高化学反应速率，但是反应过程中气体生成量很少，气体做功效能较差。炸药分解时生成大量气体，可以对纳米铝热剂的反应区提供压力补偿，因此将炸药与纳米铝热剂复合成为近年来的一个研究热点。前期研究结果表明将二者复合时可以产生协同作用，且复合物在绿色起爆药剂及微尺寸含能器件能源方面极具应用前景。然而前期研究中纳米铝热剂与炸药的结合均基于随机混合，受限于复合材料在微观组成上的无序性，对于纳米铝热剂与炸药间复合协同作用产生的机理至今尚不明确。本项目拟从界面反应性角度出发，基于可控构建纳米RDX有序内嵌三维Al/CuO含能体系，通过化学热力学及动力学分析深入研究该纳米复合含能材料的能量释放特性，并结合对化学反应机理的深入分析，揭示复合协同作用产生的机理。本项目的开展可为“纳米铝热剂/炸药”这一新型纳米复合含能材料的研发提供理论及应用基础。

炸药与纳米铝热剂复合是近年来的研究热点之一，前期研究表明将两者复合时存在相互促进作用，且复合物在绿色起爆药剂及微尺寸含能器件能源方面极具应用前景，然而有许多相关科学问题尚待解决。本课题主要围绕该方向开展了两方面的研究工作。其一是通过物理气相沉积技术将CuO均匀包覆在亚微米RDX表面以制备得到RDX@CuO，由此实现组分间紧密的界面接触与均匀分布，并通过与RDX-CuO无序混合物中RDX的热分解峰温及表观活化能做比较，研究组分间界面结合状态对RDX热分解特性的影响；其二是通过对比分析RDX、RDX-Al、RDX-CuO及RDX-Al-CuO中RDX的热分解峰温、分解热及表观活化能值，研究纳米Al及纳米CuO是否对RDX的热分解具有协同促进作用。主要结论如下：（1）RDX、RDX@CuO及RDX-CuO中RDX的热分解峰温及表观活化能值呈以下顺序：峰温，RDX@CuO<RDX-CuO<RDX；表观活化能，RDX@CuO≈RDX-CuO <RDX。RDX@CuO中组分间紧密有序的界面结合可以影响RDX的热稳定性，进而相较于RDX-CuO进一步降低了RDX的分解峰温；另一方面，Kissinger法与Kissinger-Akahira-Sunose法计算结果均显示虽然RDX@CuO与RDX-CuO的分解活化能值均显著低于纯RDX，但二者间无明显差异，此外二者具有相似的可归属为Avrami-Erofeev模式的反应模型，这意味着RDX与CuO间界面结合状态并未影响RDX的分解路径。（2）RDX、RDX-Al、RDX-CuO及RDX-Al-CuO中RDX的分解峰温、分解热及表观活化能值大致呈以下顺序：峰温，RDX-Al-CuO<RDX-CuO≈RDX<RDX-Al；分解热，RDX-Al<RDX≈RDX-Al-CuO<RDX-CuO；表观活化能，RDX-CuO<RDX-Al-CuO < RDX-Al<RDX。不同于文献报道，本研究未发现纳米Al与RDX分解产物间放热反应的证据，且不同样品的分解峰温与表观活化能值大小间无明显相关性。总体来看，虽然纳米Al及纳米CuO均可分别促进RDX的热分解，但Al-CuO作为纳米铝热剂共同作用时并未对RDX的热分解表现出协同促进作用。