Effects of copper chromite and iron oxide catalystson AP/CTPB sandwiches

Abstract

Results are presented of an experimental motion-picture study designed to provide observations of catalyzed composite solid-propellant combustion. Various methods of catalyst addition were incorporated into two-dimensional sandwiches, composed of pressed ammonium perchlorate (AP) oxidizer sections laminated together with a thin layer of carboxy terminated polybutadiene (CTPB) binder. Catalysts investigated were harshaw Catalyst Cu 0202 (copper chromite—CC) and Fe 2 O 3 (iron II oxide—IO). The sandwiches were burned in a window bomb at pressures of 600 and 2000 psig. Cinephotomacrography, at a frame rate of 1600 pictures per second and magnification of 2:1, was used. Copper chromite was found to be a more effective catalyst than IO for AP/CTPB sandwich systems. Copper chromite appeared to: augment the AP-deflagration process; possibly catalyze gas-phase reactions; possibly promote gas-phase reactions in crevices between the solid fuel and solid AP (at the interface); not promote heterogeneous reactions of gases with the solid-fuel binder; not modify the pyrolysis mechanism of the solid-fuel binder. Iron oxide was found to have effects qualitatively similar to CC, with the exception that it inhibited the AP-deflagration process at 600 psig. With the exception of IO at low pressures (600 psig), the addition of CC and IO in the AP was found to be the most effective method of increasing sandwich burn rate; their addition at the AP/binder interface was less effective; and their addition in the binder did not appear to be very effective at all, at least in the sandwich configuration. These findings, concerning CC and IO catalysts, indicate that some of the theories concerning the catalytic mechanisms of CC and IO with AP/binder composite propellants are justified, whereas others are not.