ɑ-AlH3释氢动力学调控、燃烧机理及对固体推进剂能量释放影响机制

The energy level of solid propellants is a key factor affecting the operational capability and work performance of weapon equipments and spacecrafts. Because of the high amount of hydrogen storage and the rapid hydrogen release at low temperature, ɑ-AlH3 is regarded as the most potential high-energy fuel, which can significantly improve the specific impulse of propellants. However, the hydrogen release mechanism of α-AlH3 is unclear and the hydrogen release rate is uncontrolled, which should be addressed immediately. In this project, the experiment of thermal decomposition kinetics will be carried out to establish the coupling mechanism of α-AlH3 structure, external environment and hydrogen release rate, and the process, inducement mechanism and control step of hydrogen release of α-AlH3 will be revealed from the microscopic level. The technique of controlling hydrogen evolution rate will be put forward. The mechanism of α-AlH3 preheating, hydrogen evolution, aluminum shell growth, oxide evaporation, particle ignition and burnout will be studied by means of monitoring data of ignition and combustion dynamic processes of α-AlH3 and solid propellants. The impact of self-characteristics of α-AlH3 and the external environment on the ignition and combustion mechanism of components of propellants will be found, and the limit addition of α-AlH3 in solid propellants will be determined. In this project, basic scientific issues of α-AlH3 in the field of propellants will be discussed, which will provide the theoretical basis for the hydrogen evolution rate regulation of α-AlH3 and the design of propellant formulations, and which will play an important role in the development of new generation high-energy solid rocket motors.

固体推进剂能量水平是影响武器装备及航天器作战能力和工作性能的关键因素。α-AlH3高储氢量及低温下快速释氢，被视为最有发展潜力高能燃料，可显著提升推进剂比冲。但α-AlH3尚存在释氢机理不清楚及释氢速率不可控的难题亟待解决。本项目开展热分解动力学实验，建立α-AlH3结构特性、外部环境与释氢速率耦合机制，并从微观层面揭示α-AlH3释氢历程、释氢诱导机制及控制步骤，提出调控释氢速率技术方法。借助α-AlH3及固体推进剂点火燃烧动态过程监测数据研究α-AlH3预热、释氢、铝核生长、氧化层蒸发、颗粒点火及燃尽等过程反应机理，揭示α-AlH3自身特性及外界环境对推进剂各组分点火燃烧影响机制，确定α-AlH3在固体推进剂中极限添加量。本项目深入探讨α-AlH3应用于推进剂领域的基础科学问题，将为α-AlH3释氢速率调节及推进剂配方设计提供理论基础，对新一代高能固体火箭发动机的问世起到重要推动作用。

固体推进剂能量水平是影响武器装备及航天器作战能力和工作性能的关键因素。α-AlH3高储氢量及低温下快速释氢，被视为最有发展潜力高能燃料，可显著提升推进剂比冲。但α-AlH3尚存在释氢机理不清楚及释氢速率不可控的难题亟待解决。本项目（1）开展了微米／纳米级α-AlH3燃料颗粒理化特性表征、热分解／氧化动力学实验及分子动力学模拟，建立了α-AlH3结构特性、外部环境与释氢速率耦合机制，从微观层面及原子论角度揭示了α-AlH3释氢历程、释氢诱导机制及控制步骤，提出了调控释氢速率技术方法。（2）借助α-AlH3及混合燃料点火燃烧动态过程检测数据研究其预热、释氢、铝核生长、氧化层蒸发、颗粒点火及燃尽等反应机理，揭示了α-AlH3自身特性及外界环境对其点火燃烧及能量释放的影响机制。（3）模拟了α-AlH3/HTPB固体燃料氧化过程中温度及关键产物种类和数量的时间演变，研究其微观氧化机理及相互作用机制。结果发现AlH3热反应分三阶段：（1）从表面固有缺陷释氢（低于210°C，2AlH3→2Al+3H2），由于钝化反应形成Al2O3层封装所含氢。并伴随着Al核从外部到内部成核和生长，及H2氧化成H2O。（2）由无定形Al2O3转变而来的不连续γ-Al2O3 氧化层导致Al初次氧化（210-650°C，4Al+3O2→2γ-Al2O3）。（3）γ-Al2O3转变为α-Al2O3，导致氧化壳收缩和裂缝形成，且Al熔化会破坏外壳，引起Al二次氧化（高于650°C，4Al+3O2→2α-Al2O3）。另外发现：AlH3释氢后，燃料颗粒在燃烧过程中始终呈高度分散状态，这利于反应并有效减小了团聚体尺寸。本项目深入探讨了α-AlH3应用于推进剂领域的基础科学问题，将为α-AlH3释氢速率调节、稳定贮存及推进剂配方设计提供理论基础及技术保障，对新一代高能固体火箭发动机的问世起到重要推动作用。