A Metal Inorganic Framework Designed as a Propellant Burn Rate Modifier

Abstract

The kinetics of a strategically synthesized burn rate enhancer (BRE) were investigated in its reaction with ammonium perchlorate (AP). The BRE was designed for multi‐ functionality by: (1) producing reactive gases that couple with AP gas production, (2) trapping reactive gases with high surface area, and (3) exposing metal cations to incite exothermic reactions at a temperature coincident with AP decomposition. This study advances inorganic synthesis by introducing a metal inorganic framework (MIF) composed of an aluminum cation (Al+3) surrounded by inorganic “linker” molecules of oxidizing species. To increase surface area, a porous, amorphous MIF (a‐MIF) was synthesized by controlling solution properties of an acid‐base precipitation reaction. Upon gas generation, the high surface area and aluminum‐rich surface of a‐MIF accelerate AP decomposition and induce an exothermic reaction that is otherwise endothermic in thermal equilibrium analysis. AP decomposition rate was advanced by reducing peak onset temperature and increasing decomposition rate with the addition of a‐MIF (i.e., from 17% min‐1 at 401°C to 18% min‐1 at 365°C). The enthalpy of AP decomposition increased from +240 J g‐1 to ‐1040 J g‐1. Results introduce an approach for increasing the decomposition rate of solid oxidizers by demonstrating a recipe for designing and synthesizing an MIF.This article is protected by copyright. All rights reserved.