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

Abstract

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 (Tf) 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∼0.6 MPa).

Exploring the influence of additives on the ignition, combustion and quenching of electrically controlled solid propellants

“…This effect of voltage on burn rate is well established. Various studies have observed the same behavior studying ECSPs based on PVA and LP [14][15][16], and various groups have demonstrated voltage accelerated burn rates in ECSPs based on combinations AN, HAN, AP, sodium perchlorate, and ammonium dinitramide [1,2,[17][18][19][20][21].…”

“…ECSP research has focused primarily on the addition of electrically conductive additives. Bao et al observed an increase in solid phase conductivity after adding MWCNTs and graphite to PVA/HAN based propellants [17,18]. Gnanaprakash et al added tungsten to PVA/LP propellants at varying concentrations and attributed lower response times to improved ionic conductivity in [15] and a combination of bulk electrical conductivity and thermal conductivity in [16].…”

“…Gobin et al added MWCNTs to PEO/LP based ECSPs and observed that the addition of MWCNTs could maintain the solid phase conductivity of ECSPs which would otherwise have been electrically insulative [13]. These additives have been shown to reduce the response time in ECSPs but can prevent quenching under pressure which reduces the efficacy of these propellants [13,17,18].…”

“…Bao et al. observed an increase in solid phase conductivity after adding MWCNTs and graphite to PVA/HAN based propellants [17, 18]. Gnanaprakash et al.…”

Tuning the micro‐structure, laser ignition, and isovolumetric burning performance of nitrocellulose propellant via incorporation of graphene oxide

“…High thermal conductivity is conducive to faster heat transfer and higher burning rate of solid propellant, and carbon nanomaterials are widely used to tuning the burning rate of propellant due to their excellent thermal conductivity. [43,44] The influence of GO and its percentage on the thermal conductivity of NC is shown in Figure 7. Generally, the thermal conductivity of NC/GO composite propellants increases slowly with the doping of GO, and less than 2 wt% of GO is inefficient to improve the poor thermal conductivity of NC.…”