各向异性纳米铝表面设计与热性能研究

The addition of nano-aluminum in the solid rocket propellants is beneficial to obtain higher burning rate, higher specific impulse and lower signal characteristics than that of traditional micron-aluminum. The current study of nano-aluminum mainly focuses on spherical morphology. The controlled synthesis and thermal property of non-spherical anisotropic nano-aluminum have been seldom reported. On the basis of the relationship between the surface design of nano-aluminum and its thermal property, this project adopts the design technology of a nanomaterial surface crystal face to construct an anisotropic nano-aluminum and reveal the relationship among the different exposed crystal faces and the thermal release property. To enhance the activity in the anisotropic nano-aluminum surface, this material is designed to be covered evenly by the nano-catalyst of a solid propellant to form a composite structure nano-aluminum. Moreover, this project aims to explore the effect of external environmental factors on the static activity of the composite structure nano-aluminum. The assistive oxide film stripping technology is adopted to investigate the dynamic evolution of the surface oxide film of the anisotropic nano-aluminum and composite structure nano-aluminum fuels under different oxidation stages. The oxidation reaction and thermal release mechanisms of the new aluminum fuel will be used to build a model for the thermal release of oxidation reaction. Finally, the hydrophobic nano-aluminum is created through the design of a surface group, and its distribution and compatibility in solid propellants are explored to reveal the effect regularity of its distribution upon its combustion stability. Overall, the findings are expected to serve as theoretical and technical support for the application of the new nano-aluminum in the military, national defense, and other fields.

纳米铝代替传统微米铝作为固体火箭推进剂的金属燃料，有助于提高推进剂的燃速、比冲和降低特征信号等。当前，纳米铝研究多侧重于热力学稳定的球状形貌，少见针对非球形各向异性纳米铝的结构调控及其热性能研究。本项目立足于纳米铝表面设计与热性能的关系，采用纳米材料表面晶面设计技术，首先构建各向异性纳米铝，研究不同晶面暴露与热性能间的关系；接着，为提高各向异性纳米铝有效活性，在其表面均匀包覆推进剂用纳米催化剂形成复合纳米铝，研究外界环境因素对复合纳米铝静态活性的影响；然后，采用项目组提出的氧化膜剥离辅助技术，研究各向异性纳米铝和复合纳米铝的动态氧化反应过程和热释放机理；最终，采用表面基团修饰设计构建疏水性纳米铝，以增强与推进剂组分的相容性，研究修饰后纳米铝在推进剂中的分散状况，揭示分散性对燃烧稳定性的影响规律。项目研究成果有望为各向异性纳米铝在我国军事、国防工业等方面的应用提供理论和技术支撑。

项目利用化学合成或物理沉积等多种技术途径，通过思路创新和方案优化，设计制备出多种各向异性纳米铝及其复合物，并对热性能进行了详细研究。首先，采用湿化学法，精准调控有机溶剂中铝盐的还原参数，设计制备出二维超薄纳米铝片，纳米铝片定向生长的关键是（111）晶面的选择性氧吸附，且纳米铝片具有良好稳定性；采用低浓度酸、碱或氟化物对表层氧化膜进行微腐蚀，设计调控出多孔表面铝燃料，多孔结构增加了氧化反应的活性位点，提升了高温热反应性能。接着，在铝燃料表面包覆推进剂用燃速催化剂，或将其沉积在燃速催化剂上，设计构筑出集高效燃烧与催化一体的复合燃料。比如：通过磁控溅射沉积，设计制备出包覆层可调的一维纳米铝/过渡金属氧化物复合燃料，该燃料具有优异的点火燃烧性能；通过铝表层氧化膜的原位破除和纳米金属的定向沉积，设计制备三维纳米花状钴/铝等多种双金属燃料，纳米金属包覆层实现了铝燃料高温下剧烈的各向异性氧化。最后，项目研究了复合铝燃料对推进剂燃烧稳定性的影响，证实复合铝燃料有利于AP基推进剂的稳定燃烧。项目研究成果为各向异性纳米铝在我国军事、国防工业等方面的应用提供理论和技术支撑。