PROCESSING OF ENERGETIC MATERIALS FINE POWDERS USING FLUID ANTISOLVENT METHOD

摘要

The antisolvent effect is a process known to extract solute from saturated solution. The use of an antisolvent fluid as CO_2 expects several advantages compare to conventional industrial methods. The size and the dispersion of the powders are generally small. The concentration of the solution and the nature of the solvents play an important role on the feature of the powders. The possibility of recycling CO_2 fluid decreases the use of organic solvents and improves the quality of the process towards the environmental problems, The first application of supercritical antisolvent micronization of nitroguanidine was proposed by Gallagher el al. with different liquid solvents and two different antisolvents were tested: chloro-difluoromethane and CO_2. They observed various morphologies: spheres, large crystals, snowballs and starbursts. Particles dimensions ranged from 1μm to hundreds of micrometers. The principle of antisolvent effect is to broke the saturation of a saturated solution by the wanted powder by the introduction of a second solvent witch moves the equilibrium of solubility and causes the precipitation of the solute. In the present communication, the crystallization and the characterisation by SEM of an energetic powder has been carried out with CO_2 as gas antisolvent at 313, 15 K. Some articles about this energetic powders like RDX and HMX treat experimental conditions of the process. New results on the determination of the parameters of fine powders of HNIW by antisolvent process are presented. Indeed, this product shows growing interest in the field of rocket fuel and this process can be achieve in high conditions of security.