%0 Journal Article %A Nguyen, T. T. %D 1997 %I Begell House %N 1-6 %P 679-692 %R 10.1615/IntJEnergeticMaterialsChemProp.v4.i1-6.640 %T New Insights into the Combustion of AP/HTPB Rocket Propellents: The Catalyst Active Sites and a Combustion Flame Model for The Ferrocene-Catalysed Combustion %U https://www.dl.begellhouse.com/journals/17bbb47e377ce023,43cb1df7484a24f3,66d967dc485fab8a.html %V 4 %X The combustion of solid rocket propellants consisting of hydroxy-terminated polybutadiene (HTPB) as binder and ammonium perchlorate (AP) as oxidiser and incorporating the ferrocenic burn rate catalysts Catocene and Butacene was examined with a view to: (i) obtaining a better understanding of the propellant combustion behaviour and the prevailing mechanistic sites of burn rate catalysis, and (ii) determining the burn rate temperature sensitivity.
Examination revealed that the enhancing effect of 1% Catocene was equivalent to 0.5% Butacene. The combined experimental evidence (from burn rate measurements and scanning electron microscopy) provides insights into the possible sites of the catalytic action by the ferrocenic catalyst. The data were interpreted as indicating the catalyst acting predominantly in the binder, possibly to promote AP/binder reactions at the AP/binder interface, or to enhance the binder pyrolysis. There could be, possibly to a much less extent, active sites formed by iron particles ejected into the primary diffusion flame. There was no evidence suggesting the catalyst acting in the oxidiser to promote surface AP decomposition. The arguments support the logic that the combustion is controlled by the primary diffusion flame. A combustion flame model is proposed which shows the domed AP surface particle, undercutting along the AP particle boundary, and the primary diffusion flame bending across the AP/binder interface.
The burn rate temperature sensitivity value (σp) at 10 MPa for the propellants containing 0.5% Catocene and 0.5% Butacene was 0.17 and 0.15%/°C, respectively. This represents a reduction of 40% and 35%, from the baseline non-catalyst value. The lowering of bum rate temperature sensitivity re-affirms the contention that a primary diffusion flame mechanism is operative for the ferrocene-catalysed combustion. %8 1997-01-01