Effect of pressure and some lead salts on the chemistry of solid propellant combustion

Abstract

Final combustion products have been measured at 1, 20 and 40 atmospheres pressure for laser-ignited thin film samples of nitrocellulose (12.6% N) and 60% NC-40% NG composition, as well as for the single base and double base propellants catalyzed by lead oxide or lead salicylate. Experiments have also been carried out with nitrocellulose samples pretreated with NO 2 or water vapor, or burned in an atmosphere containing oxygen. Lead catalysts lead to an increase in CO 2 relative to CO at pressures where super rate burning is expected. This is an exothermic process, and explains the higher surface and dark zone temperatures, the higher caloric heat output, and faster burning rates for the leaded propellants. With increasing pressure, CO increases relative to CO 2 and NO is reduced to N 2. Dissolved water vapor or pretreatment with NO 2 have no measureable effect on the combustion chemistry, but small amounts of O 2 catalyze the oxidation of CO to CO 2, and the reduction of NO to N 2. Mechanisms are proposed to account for these observed features of solid propellant combustion chemistry.