Burn Rate Enhancement of a Solid Nitrocellulose Monopropellant using Functionalized Graphene Foam Microstructure

摘要

The control and enhancement of the combustion wave propagation velocities of solid monopropellants is very important for the development of low cost and efficient micro power systems such as microthrusters and thermal-to-electrical energy conversion devices. In this work, the functionalized form of a highly-conductive, porous, three-dimensional graphene foam (F-GF) structure was used to enhance the bum rate of a solid monopropellant, nitrocellulose (NC). The GF structure was doped (or functionalized) with a transition metal oxide (TMO), magnesium dioxide (MnO_2), which acted as catalysts and thus, aid in the decomposition of the solid-propellant. Self-propagating combustion waves were observed, with average flame speed enhancements up to 5 times the bulk value. Such a significant enhancement was attributed to the coupled physical and chemical effects. The physical effects due to the enhanced thermal conductivity in the flame speed propagation direction because of the GF structure and the chemical effects due to the reduction of the activation energy because of the TMO. The fuel loading was kept fixed at 95% but the amount of the TMO added was varied by changing the concentration of the doping solution from 2mM to 30mM. The burn rate enhancement showed a parabolic trend as a function of the doping concentration and an optimum value of 20mM was obtained.