The effect of decorated graphene addition on the burning rate of ammonium perchlorate composite propellants

Catalysts are often added to solid propellant formulations to tailor burning rates. Nanocatalysts can increase propellant burning rates over standard catalyst sizes due to the increase in surface area per unit weight. However, the increased surface area that the binder must wet can be prohibitive if large amounts of nanocatalysts are used. Additionally, agglomeration of the nanocatalyst can result in micron-scale particles, reducing catalyst effectiveness. In this study a nanoscale iron oxide catalyst has been used to decorate graphene. By decorating graphene with the catalyst, nanoscale features are kept but the catalyst is stabilized to reduce agglomeration. Changes in burning rate between the catalyzed and uncatalyzed propellants are investigated. The effect on burning rate of encapsulating the catalyst inside the fine AP crystals compared to propellants where it is added to the binder is also investigated. We also compare propellants with decorated graphene and propellants with undecorated graphene catalysts. The three comparisons are made for two different graphene preparation methods. It is found that the highest burning rates occur in propellants where the graphene is decorated with catalyst and encapsulated in the fine AP. The next highest burning rates occur in propellants with decorated graphene that is physically mixed into the propellant. The lowest burning rates are found in propellants where the graphene is undecorated, where there is little difference between encapsulated or physically mixed graphene blanks, or compared to a baseline propellant. Burning rates are found to be similar between graphene preparation methods considered.