Ammonium nitrate (AN) has received attraction globally not only as a nitrogenous fertilizer but also as an oxidizer in gas generators and propellants. Nowadays, great attention is being focused on the development of composite solid propellants with green oxidizers in realizing eco–friendly combustion products. The ammonium perchlorate (AP), which is the work horse oxidizer in composite propellant, needs replacement due to its environmental and human health issues. In this context, AN is regarded as an alternative to AP because of its easy availability and environmentally friendly chlorine free combustion products. However, AN has its own inherent drawbacks such as hygroscopicity, room temperature phase transition, and low burning rate. Recently, several studies have been focused on its phase stabilization and burning rate modification so as to develop solid propellants with improved properties. The knowledge of thermal characteristics of AN is a crucial factor for its applications in propellants and gas generators. This article details the different aspects of polymorphism, phase stabilization, thermal decomposition, hygroscopicity, specific impulse, and burn rate modification of AN and also addresses ways to overcome the inherent weakness of AN as a propellant oxidizer in formulating an effective propellant composition.

中文翻译：

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硝酸铵作为复合固体推进剂的生态友好氧化剂：承诺和挑战

硝酸铵（AN）不仅作为一种含氮肥料而且在气体发生器和推进剂中作为氧化剂而受到全球的关注。如今，在实现绿色环保燃烧产物方面，人们非常重视开发具有绿色氧化剂的复合固体推进剂。高氯酸铵（AP）是复合推进剂中的工作马氧化剂，由于其环境和人类健康问题，需要更换。在这种情况下，AN被认为是AP的替代产品，因为它易于获得并且对环境友好，无氯燃烧产物。然而，AN具有其自身的固有缺点，例如吸湿性，室温相变和低燃烧速率。最近，一些研究集中在其相稳定和燃烧速率改变上，以开发具有改进性能的固体推进剂。AN的热特性知识是其在推进剂和气体发生器中应用的关键因素。本文详细介绍了AN的多态性，相稳定，热分解，吸湿性，比冲和燃烧速率修饰的不同方面，并探讨了克服AN作为推进剂氧化剂在配制有效推进剂组合物中固有的弱点的方法。