氧烛中锰金属粒径对氯酸钠热解的催化作用

分别制备了两组粒径的Mn金属燃料(平均粒径分别为18.73和5.24 μm),利用激光粒度分析仪测试了其粒径分布,扫描电镜分析了表面形貌,能谱仪确定了所含元素.对NaClO₃,NaClO₃与Co₃O₄,NaClO₃、Co₃O₄与Mn的混合物分别进行了热重与示差扫描量热联合分析实验(TGA-DSC),通过对比各混合物热解起始温度及其他特征温度,探究了Mn金属粒径对NaClO₃热解的催化强度与热解稳定性的影响.研究结果表明:Co₃O₄虽对NaClO₃热解具有催化性,热解开始温度(T_o)由512.3℃下降为333.0℃,但其可导致NaClO₃热解的不稳定,热解阶梯由1个变为3个;Mn金属燃料对NaClO₃中间产物具有明显的催化性,且随着粒径减小,催化强度逐渐增加,热解终止温度(T_f)由419.8℃下降为351.9℃,同时NaClO₃热解阶梯减少,热解温度区间变窄(由180.6℃减小为19.4℃),热解更加稳定.

Catalytic effect of Mn particle size on thermal decomposition of sodium chlorate in oxygen generators

Two groups of Mn metal fuels with different particle-size distributions were prepared with median diameters of 18.73 and 5.24 μm. The particle-size distribution was measured by a laser particle-size analyzer, the surface morphology was analyzed via scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS) determined the contained elements. For the NaClO₃, the NaClO₃ and Co₃O₄ as well as NaClO₃, Co₃O₄, and Mn mixtures were subjected to TGA-DSC combined thermogravimetric analysis. The effects of the Mn metal fuel particle size on the catalytic effect and pyrolysis stability of NaClO₃ were investigated by comparing the pyrolysis onset/final temperature and other characteristics. The results show that although Co₃O₄ has a significant catalytic effect on the pyrolysis of NaClO₃, e.g., the onset pyrolysis temperature decreases from 512.3 to 333.0℃, it can lead to instability in NaClO₃ pyrolysis, namely the pyrolysis steps from 1 to 3. The Mn metal fuel has a clear catalysis effect on the intermediate products of NaClO₃ pyrolysis. With the decrease in particle size, the catalytic effect gradually increases and the pyrolysis final temperature T_f decreases from 419.8 to 351.9℃. Meanwhile, the pyrolysis step of NaClO₃ decreases and the temperature range of pyrolysis decreases from 180.6 to 19.4℃, indicating that the pyrolysis process becomes more stable.