Fabrication of Catalyst-Insertion-Type Microelectromechanical Systems Monopropellant Thruster

Abstract

A microelectromechanical systems monopropellant thruster having a design thrust of 100 mN was fabricated and tested. Hydrogen peroxide (90 wt %), which is a green propellant, was selected as the monopropellant. Platinum was used to decompose the hydrogen peroxide, and it was coated on Al2O3 via impregnation. Three catalyst loading conditions were tested and experimentally optimized. The optimized catalyst was directly inserted into the thruster chamber to enhance decomposition performance because its surface-to-mass ratio significantly affected its performance. The microelectromechanical systems thruster was composed of eight photosensitive cylindrical-type glasses. An additional reduction process was carried out after the thermal bonding procedure because performance degradation of the catalyst was detected at this stage. The microelectromechanical systems thruster decomposed hydrogen peroxide well. However, chamber instability was observed. This instability resulted from an insufficient pressure drop at the injector. Therefore, it is necessary to increase the feeding pressure and reinforce the injector wafer to decrease chamber instability.