Iron oxide is the most common catalyst in solid rocket propellant. Increased performance of propellant by encapsulating iron oxide particles within ammonium perchlorate (AP) has been previously demonstrated, but only nanoscale particles were used, and encapsulation was only accomplished in fine AP ($\sim 20$ microns in diameter). In this study, the size of the particle inclusions were extended to micron scale within the AP particles, and the particle sizes of the AP-encapsulated catalyst particles were increased to the coarse region (hundreds of microns). Fractional crystallization techniques were used with fine AP-encapsulated particles acting as nucleation sites for precipitation. This paper reports catalyst particle inclusions of micron scale, as well as nanoscale, within AP and presents characterization of this encapsulation. Encapsulating micron-sized particles and growing these composite particles could pave the way for numerous possible applications. A study of the thermal degradation of these AP-encapsulated particles compared against a standard mixture of iron oxide and AP showed that AP-encapsulated micron-scale catalyst particles exhibited similar behavior to AP-encapsulated nanoscale particles. Using computed tomography, it was found that catalyst particles were dispersed throughout the interior of coarse AP-encapsulated micron-scale catalyst particles and decomposition was induced within these particles around catalyst-rich regions.

氧化铁是固体火箭推进剂中最常见的催化剂。以前已经证明了通过将氧化铁颗粒封装在高氯酸铵（AP）中来提高推进剂的性能，但是仅使用了纳米级颗粒，并且仅在精细AP中完成了封装（$〜20$直径）。在这项研究中，颗粒夹杂物的尺寸扩展到AP颗粒内的微米级，并且AP包封的催化剂颗粒的颗粒尺寸增加到了粗糙区域（数百微米）。使用分级结晶技术，将细小的AP封装颗粒用作沉淀的成核位点。本文报道了AP内微米级和纳米级的催化剂颗粒夹杂物，并介绍了这种封装的特征。封装微米尺寸的颗粒并生长这些复合颗粒可为多种可能的应用铺平道路。与氧化铁和AP的标准混合物相比，对这些AP包封的颗粒的热降解研究表明，AP包封的微米级催化剂颗粒表现出与AP包封的纳米级颗粒相似的行为。使用计算机断层摄影术，发现催化剂颗粒分散在整个粗糙的AP包封的微米级催化剂颗粒的内部，并且在富含催化剂的区域周围的这些颗粒内引发分解。