Effect of ultrafine aluminum on the combustion of composite solid propellants at subatmospheric pressures

This paper presents the results of an experimental study of the combustion of composite solid propellants with a double oxidizer (ammonium perchlorate/HMX) at pressures of 0.03–0.1 MPa. Systems containing a micron-sized aluminum powder (ASD-4) and the Alex ultrafine aluminum powder were investigated. It was shown that the replacement of ASD-4 by Alex in propellant systems led to an increase in the burning rate. The aluminum particle size and the oxidizer excess coefficient were found to affect the exponent in the power-law burning-rate dependence. The range of the oxidizer excess coefficient was determined that corresponded to the effective replacement of micron-sized aluminum by ultrafine aluminum for which the exponent in the power-law burning rate dependence decreases.