Exploring the Influences of Conductive Graphite on Hydroxylammonium Nitrate (HAN)-Based Electrically Controlled Solid Propellant

The electrically controlled solid propellant (ECSP) has many advantages that are not available with traditional propellants, such as multiple start/stop operations and controllable thrust. In this research, conductive graphite (C) was employed as an additive to hydroxylammonium nitrate (HAN)-based ECSPs to enhance electrical conductivity and thermal conductivity, and the influences of C on the burning characteristics of ECSPs were investigated by some characterization methods. The addition of 5 % C increases the electrical conductivity and thermal conductivity by 13.2 % and 18.9 %, while reduces the theoretical specific impulse (Isp) and adiabatic flame temperature (T-f) by 7.9 % and 18.4 %. C acting as electric and heat energy transfer media was demonstrated by TG-DSC. ECSPs containing 1 %, 3 %, and 5 % C reinforce the burning rate by 11.4 %, 25.6 %, 35.9 % and mass loss by 6.9 %, 22.3 %, 47.8 % at 200 V; and enhance the burning rate by 39.2 %, 62.4 %, 104.9 %, and mass loss by 46.7 %, 84.7 %, 200.1 % at 0.6 MPa. This can be explained by the fact that the increase in electrical conductivity promotes the electrochemical decomposition rate of the ionic oxidizer in ECSPs at atmospheric pressure (0.1 MPa) and the rise in thermal conductivity promotes the heat transfer to the unburned zone of the propellant under high pressure (0.2 MPa similar to 0.6 MPa).