Burning characteristics of ammonium nitrate propellant containing fine ammonium perchlorate – influence of porosity of ammonium perchlorate**

Abstract

Fine porous ammonium perchlorate (PAP) has small holes in its crust, and the voids in the particles are connected to the outside. The porosity of PAP results in fine bubble contamination in a propellant because the voids in PAP cannot be completely charged with a binder. Fine bubble contamination can improve the burning rate characteristics of an ammonium perchlorate (AP) propellant. The influence of the porosity of PAP on the burning characteristics of an ammonium nitrate (AN)/AP propellant and the effect of Fe 2 O 3 as a catalyst on them were investigated in this study. The void fraction of the propellant increased with increasing mass ratio between AP and all oxidizers (ξ) and ranged from 1.3 % to 3.2 %. The porosity of PAP increased the burning rate of AN/AP propellants. This effect increased with decreasing pressure and was independent of ξ. However, porosity had minimal influence on the burning rate of AN/AP propellants with Fe 2 O 3 . The effect of the catalyst on the increase in the burning rate due to the porosity of PAP was influenced by pressure and ξ. The effect on the AN/AP propellant was greatest when ξ was in the 0.5-0.6 range. K E Y W O R D Sammonium nitrate, ammonium perchlorate, burning characteristics, porosity, propellant | INTRODUCTIONAmmonium nitrate (AN)-based composite propellants, that is, those prepared using AN as the oxidizer, have gained popularity as fuels for side thrustors and gas generators, despite major problems associated with their use, such as low burning rate, poor ignitability, and low energy [1][2][3][4]. This is because AN-based propellants are chlorine-free, with low hazard and low observable emissions (minimal smoke). Numerous approaches have Symbols and Abbreviations: AN, ammonium nitrate; AP, ammonium perchlorate; FAP, fine ammonium perchlorate; PAP, fine porous ammonium perchlorate; n, pressure exponent; R f , rate of burning rate of an AN/PAP propellant to that of an AN/FAP propellant for propellant containing Fe 2 O 3 ; R ff , ratio of burning rate of an AN/FAP propellant with Fe 2 O 3 to that of the corresponding propellant without Fe 2 O 3 ; R p , rate of burning rate of an AN/PAP propellant to that of an AN/FAP propellant for propellant without Fe 2 O 3 ; R pf , ratio of burning rate of an AN/PAP propellant with Fe 2 O 3 to that of the corresponding propellant without Fe 2 O 3 ; ξ, mass ratio between AP and all oxidizers.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Traditional vs. Energetic and Perchlorate vs. “Green”: A Comparative Study of the Choice of Binders and Oxidising Agents

“…It is also possible to fine-tune both the porosity and particle size of AP [13], as well as to modify its reactivity by supplementing it with catalysts, typically metal oxides [14,15]. The main drawback of AP is that its combustion results in the formation of hydrogen chloride, chlorine, and chlorine oxides, which are highly problematic atmosphere pollutants [16,17]. Consequently, significant research interest is devoted to developing oxidising agents for solid propellants that can replace AP.…”