Improvement in energy release properties of boron-based propellant by oxidant coating

• NH4ClO4, KNO3, KClO4 and HMX coated B were used to prepare propellant samples.
• FTIR, XRD and SEM were used for the microstructure analysis of the prepared B.
• Thermal oxidation and combustion characteristics of the propellants were studied.
• HMX coating was the most beneficial to the energy release of the samples.

The energy release properties of a propellant can be improved by coating boron (B) particles with oxidants. In the study, B was coated with four different oxidants, namely, NH4ClO4, KNO3, LiClO4, and cyclotetramethylenetetranitramine (HMX), and the corresponding propellant samples were prepared. First, the structural and morphological analyses of the pretreated B were carried out. Then, the thermal analysis and laser ignition experiments of the propellant samples were carried out. Coating with NH4ClO4 showed a better performance than mechanical mixing with the same component. Coating with KNO3 efficiently improved the ignition characteristics of the samples. Coating with LiClO4 was the most beneficial in reducing the degree of difficulty of B oxidation. Coating with HMX was the most beneficial in the heat release of the samples. The KNO3-coated sample had a very high combustion intensity in the beginning, but then it rapidly became weak. Large amounts of sparks were ejected during the combustion of the LiClO4-coated sample. The HMX-coated sample had the longest self-sustaining combustion time (4332 ms) and the highest average combustion temperature (1163.92 °C).