Formulation effect on combustion and agglomeration characteristics in nitramine solid propellants

The formulation fundamentally determines the combustion characteristics and agglomeration behavior of propellants. This study compared the effects of four factors on the combustion, agglomeration, and combustion efficiency of nitramine solid propellants: the aluminum size, the ammonium perchlorate size, the nitramine size, and the mass ratio of ammonium perchlorate to nitramine. The comparison was conducted through a series of experimental methods including burning rate tests, collection of the condensed-phase combustion products, chemical titration, and physicochemical analysis. In terms of burning rate, reducing the particle sizes of aluminum powder and ammonium perchlorate, increasing the nitramine size, and increasing the mass ratio of ammonium perchlorate to nitramine all effectively enhance the burning rate. The influence of these four factors on burning rate, in descending order of impact, is: the mass ratio of ammonium perchlorate to nitramine > the ammonium perchlorate size > the aluminum size > the nitramine size. Regarding agglomeration and combustion efficiency, increasing the particle sizes of aluminum and nitramine, increasing the mass ratio of ammonium perchlorate to nitramine, and decreasing the ammonium perchlorate size can effectively inhibit agglomeration and enhance combustion efficiency. Among these, the ammonium perchlorate size has the greatest effect on enhancing the combustion efficiency, potentially increasing it by 16%. The nitramine size has the weakest impact on combustion efficiency, with a potential increase of 5.5%. The experimental results of this study can provide references for a deeper understanding of the combustion mechanisms of nitramine solid propellants, the establishment of combustion models, and the realization of formula optimization.