Study On The Preparation And Application Of The Supercritical Fluid Technology In The Manufacturing Of The Structural Micro-foam Propellants

The applications of supercritical fluids to the processing of propellants were researched preliminary in this paper. The principles and technology of the processing of the structural micro-foam propellants were studied combined with the theoretical analysis of solubility and diffusion of the supercritical fluids in the nitrocellulose-based propellants, as well as the mechanisms of the nucleation and the micro-pore growth in these systems. The main works are as follows:The multi-supercritical fluids were formed by adding some optimum solvents of nitrocellulose into the supercritical CO2fluid in order to improve the solubility of supercritical fluids in the nitro-cellulose based propellants with rigid structures and provide enough quantity of CO2for the foaming process. The solubility of supercritical fluids and multi-supercritical fluids in nitrocellulose was studied.The solubility diffusion behavior and the desorption mechanism of the supercritical fluids in propellants were analyzed. The methods for the measuring of the solubility diffusion behavior of supercritical CO2in the propellants were also studied and the diffusion coefficients of supercritical CO2, supercritical CO2/ethanol and supercritical CO2/acetone fluids in the propellants were further acquired.The nucleation theory of micro-foams and the mechanism of the pore growth in the supercritical fluid-propellant systems were researched, and the factors affecting the morphology of micro-pore propellants were analyzed. Adopting double-base oblate spherical propellants as target samples, the effects of foaming process parameters, additional micro-sized particles and the using of multi-supercritical fluids on the foam morphology in the propellants were studied, and the measures of controlling the foam morphology were then presented.In this paper, the micro-foam single base propellants, micro-foam oblate spherical propellants with shell-core structure and very high burning rate propellants were prepared for the first time by supercritical fluids technique.The burning performances of the propellants containing the shell-core structure were investigated by the closed bomb tests. The results indicated that the propellants with the shell-core structures had an obvious advantage of burning progressivity. Meanwhile the burning rates at different pressures of high burning rate TEGDN propellants were studied by the closed bomb tests as well as the strand burner.