Activated charcoal - A novel burn rate enhancer of aluminized composite propellants

This paper reports the discovery of activated charcoal as an effective burn rate enhancer of aluminized composite solid propellant. Experiments were carried out using a strand burner at pressures ranging from 10 to 70 bar with varying fractions of activated charcoal. The results show that with the addition of activated charcoal in an aluminized composite propellant higher burn rates (in excess of 25 mm/s at 70 bar) were obtained. This paper also explores the possibility of further enhancing the burn rates of aluminized composite propellant by using iron oxide along with activated charcoal. Burn rates recorded with iron oxide and activated charcoal both present in the propellant were in excess of 50 mm/s at 70 bar. It was noticed that these high burn rates were accompanied by a higher (0.65) pressure index of combustion. A series of experiments were designed to understand the burn rate enhancement with activated charcoal in aluminized composite propellant. TGA and DSC tests were carried out on AP pellets with and without activated charcoal to detect any condensed phase activity of activated charcoal. These tests did not show any significant difference between the AP pellets with and without activated charcoal. The AP pellets with and without activated charcoal were also burnt in a strand burner to understand if any gas phase reaction was being catalyzed by activated charcoal. AC does not enhance any gas phase activity while addition of AC in AP increased the LPDL of AP and reduced the burn rate. Lastly, sandwich propellant with activated charcoal at the interface was prepared to determine if interface reactions were being affected with the addition of activated charcoal. It has been observed that with the addition of activated charcoal at the AP-binder interface the burn rates are higher than those recorded without activated charcoal at the AP-binder interface. (C) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.