Generation of BN in the Combustion Residue of Boron-Containing Propellant

Residue analysis of boron-containing propellant burned in the primary and aft-mixing combustors of a solid propellant ramjet (SPRJ) indicated that a considerable amount of boron nitride (BN) was created in addition to the main product of B 2 O 3 . The formation heat of BN is far less than that of B 2 O 3 , which brings some disadvantage to the heat release of boron. Ignition and combustion of boron are carried out in an oxygen bomb Calorimeter. Thermoanalysis, X-ray diffraction, elementary analysis, and X-ray photoelectron spectroscopy are adopted to investigate the source of BN, the effect of air pressure, and the effect of oxidizers. The results show that the output of BN increases with the rising of air pressure, N 2 is proved to be the main origin of elemental nitrogen in forming BN, and a competition effect exists between the oxidation and nitrification of boron.