Combustion phenomena of boron containing propellants

The combustion of boron-contg. propellants, based on AP/GAP and AP/HMX/GAP formulations, was investigated by applying fast spectroscopic, pyrometric, and photog. techniques. The propellants burn at a rate of 17 mm/s at 5 MPa. Addn. of an iron oxide (Fe2O3) catalyst increased the rate to 20 mm/s at the same pressure. The detd. av. pressure exponents were 0.66 without and 0.57 with Fe2O3 catalyst. At >5 MPa, a strong decrease in the exponent was obsd. The reaction zones showed high particle concns. at 1500-2000 K, which varied with the nitrogen pressure. Reacting with air, the particle temps. increased close to the evapn. temp. (2200 K) of boron oxide. The reaction of boron with oxygen was proved by the results of spectroscopic data. Considering an application in a ducted rocket, the boron was heated to the desired reaction temp.