Combustion Behaviour of Solid Propellants for Micro-Thruster

摘要

Solid propellants for micro-thruster are required to have high thermal sensitivity and a lower critical condition of ignition as well as excellent filling properties. The energy properties of ammonium perchlorate (AP)/hydroxy-terminated polybutadiene (HTPB), APitrocellulose (NC), lead styphnate (LS)/NC and LS/dibasic lead stearate (SQ-2) were obtained from thermodynamic calculations. Thermal decomposition characteristics of LS/NC and LS/SQ-2 mixtures were investigated for different species ratios. The formula ratio of LS to NC was tested for 1:1, 6:4, and 7:3, and the ratio of LS to SQ-2 was tested for 4:6, 1:1,6:4, and 7:3, respectively. Ignition powers of LS/NC and LS/SQ-2 were measured, the formula ratio of LS to NC and LS to SQ-2 was 1:1, 6:4, 7:3, and 8:2, respectively. Micro-impulse tests were carried out for micro-thrusters with a charge of 0.08 mg and 0.1 mg, respectively, and compared with the thrust and impulse obtained by simulations. Results indicated that the thermal stability of LS is decreased by adding NC or SQ-2 to it, meanwhile, the energy produced is promoted. The addition of NC is more effective. The ignition power is 2.16 W when the proportion of LS to NC is 1:1. The average thrust peak from 0.08 mg propellant is measured as 0.1543 N, the average impulse is about 6.34 × 10~(-5) N × s. The thrust peak is 11.89% higher than the calculated simulation value, while the total impulse is 17.99% higher. The measured average thrust peak of 0.1 mg is 0.1789 N, which is 18.3% higher than the calculated value, while the average impulse is about 7.48 × 10~(-5) N × s and 16.6% higher than the calculated value.