Effect of catalyzer on primary combustion and mechanical properties of highly metalized fuel-rich propellants

Highly metalized fuel-rich propellants containing 40-50% nano-micro aluminum and the cata-lyzed compositions comprise ultra-fine iron oxide (UFIO) content of 0.3-2.0% were considered. Primary combustion features and mechanical properties of these propellants were investigated for water ramjet propulsion applications. These propellants exhibit almost 70% burning rate en-hancement at all the tested pressures with UFIO catalyzed ones as compared with uncatalyzed compositions. Simultaneously, the burning rate pressure exponent of these UFIO catalyzed pro-pellants was considerably reduced. The quenched agglomerates from the primary combustion ex-hibit over wider size ranges from few microns to few millimeters, which are of several times larger as compared with parent Al particles. The number density effect of Al particles causing the ag-glomeration at the burning surface outweighs the particle size and catalyzer effect in these highly aluminized propellant compositions. The crack free propellant grain structure was achieved by optimizing the molding pressure range and the rate of compaction. Addition of UFIO increased the compressive strength marginally whereas it reduced the elastic properties of the propellant grain marginally.