Effect of Boric Acid on Electronically Controlled Solid Propellants

Electrically controlled solid propellants (ECSPs) were modified with boric acid (HB). HB affects ECSPs’ combustion performance by changing the volume conductivity. Increasing the HB content can enhance the compressive properties by further increasing the crosslink density of the ECSPs. Based on the calculation results of NASA’s Chemical Equilibrium with Applications program, HB has no apparent effect on the specific impulse and adiabatic flame temperature of the propellant. The volume conductivity of the ECSPs were measured using a three-electrode system. After the addition of HB, the volume conductivity of the ECSPs decreased. In the process of thermal decomposition, the addition of HB can improve the thermal stability of ECSPs as a whole, although this effect is small. The effects of HB on the combustion rate and minimum theoretical ignition voltage of hydroxyammonium nitrate (HAN)-based propellants were studied at 0.1 MPa. The results demonstrate that the combustion rate of HAN-based propellants increases with increasing voltage, and that this characteristic is not affected by HB. However, the combustion rate decreases with increasing HB content, and the minimum theoretical ignition voltage increases accordingly.