Formulation & Storage Studies on Hydrazine-Based Gelled Propellants.

Abstract

The current trend in the area of high energy storable liquid rocket propellant research is to develop gelled/metallized systems and to explore the feasibility of their application in rocket motors. The idea stems from the fact that the conversion of a conventional liquid propellant to a gelled state and its subsequent metallization has the potential to significantly enhance the performance and density specific impulse. However, it is mandatory that the gelation of the liquid propellant be brought about with a minimum concentration of gellant and the gel formed should show a shear-thinning behaviour and good storage life. Keeping this in view, an experimental program to prepare thixotropic gels of hydrazine and its methyl substitutedderivatives like monomethyl hydrazineand unsymmetrical dimethyl hydrazinewas conducted under ambient conditions. The gellants investigated included particulate, chemical and synthetic materials. The gelation of the liquid fuels ..ould be brought about with gellant concentration as low as I wt per cent in some cases. Metallized gels using up to 40 wt per cent of AlIMg metal powders could be formulated. These heterogeneous systems showed a reduction in critical gellant concentration with degree of metallization. Further, less gelation time is observed if the gellant concentration is kept fixed and metal content is increased. The storage studies on gelled systems conducted over a period of three months showed good stability. The metallized systems, however, showed the settling of metal powders in meagre concentration which does not pose a major problem as these gels could be re-homogenized with stirring.