Catalytic effect of ferrous oxide on burning rate of condensed mixtures

Abstract The catalytic effect of Fe 2 O 3 on the burning rate, μ, of condensed mixtures was studied. Ammonium (AP), potassium (PP), iminomethylamine (formamidine-FP) and tetramethylammonium (TMAP) perchlorates were used as oxidizers and polymethylmethacrylate (PMM), polystyrene (PS), sool, sulphur, and guanidine nitrate (GN) as fuels. For AP-PMM mixtures, the catalyst effectiveness Z (=μ/μ o , where μ o is the burning rate of an uncatalyzed mixture) increased with pressure. The magnitude of Z for AP + PMM and AP + PS mixtures decreased as the ambient temperature increased. When the catalyst content m c was increased, a steep increase in μ and Z was observed at small m c , but at m c > 1 to 5% the value of Z increased only slightly. The catalyst effectiveness decreased as the burning rate, u o , of an uncatalyzed mixture increased (dependence Z max = A / u o 0.65 was obtained). AP- and FP-based mixtures were much more sensitive to catalysis by Fe 2 O 3 than the PP- and TMAP-based mixtures, however Fe 2 O 3 was an excellent catalyst of TMAP when u o was decreased by adding diluents (KCl, NH 4 Cl or Al 2 O 3 ). A simplified diffusion-controlled model is proposed, taking into account the competition of catalytic and homogeneous reactions. The chemical mechanism of catalysis in the burning zone is discussed.