皮秒和纳秒单脉冲激光加热Al/NC复合纳米含能材料的热动力学分析

Thermal dynamic analysis of picosecond and nanosecond single pulse laser flash-heating of Al/NC nanoenergetic composites

对纳米金属颗粒复合含能材料这一新兴体系的单脉冲激光作用的热动力学过程进行了理论分析.推导了分散在介质中的纳米金属颗粒吸收脉冲激光能量的瞬时功率密度.从热分解机理出发对纳米金属铝复合硝化纤维(Al/NC)薄膜吸收脉冲激光能量过程以及伴随着放热化学反应的热点热量传播过程进行了数值模拟,计算了不同质量分数的Al/NC薄膜样品分别在100ps,10ns,25ns脉冲激光作用下的化学反应直径.计算结果与实验数据相比较,表明了热分解基本符合10ns,25ns脉冲激光引发含能材料反应的机理,但它并不符合100ps脉冲激光作用过程.

Thermal dynamic process of single pulse laser-induced reaction is theoretically analyzed for a novel system of composite energetic materials containing nanometallic particles.The instantaneous power density of laser energy absorbed by nanometallic particles dispersed in a matrix is exactly deduced.The process of absorbing pulse laser energy for nanometallic aluminum particles embedded in nitrocellulose（Al/NC） thin film and the heat propagation process of hot spot accompanying exothermic chemical reaction are simulated numerically based on thermal decomposition mechanism.The reaction diameters are calculated for different concentrations of Al/NC thin films flashed by 100ps,10ns and 25ns single pulse laser with the reaction threshold intensities having been obtained from experiment,respectively.Calculation results are compared with the experiment data,which shows that the thermal decomposition mechanism generally corresponds to the reaction processes of 10ns and 25ns pulse laser but does not correspond to that of the 100ps pulse laser.