Measurment Of Crystallization Metastable Zone And Study On Particle Size Control Of Ammonium Perchlorate

Ammonium perchlorate (AP) is the most commonly used oxidizer of composite solid propellant, it plays an extremely important role in the solid propellant. With the deepening of AP applications, the requirement of particle classification is proposed. At present, particle gradation of AP achieves based sieving generally in industry. However, sieving can extend the period of industrial production and even cause danger due to static electricity. This article mainly studied particle size control of AP crystallization process in order to obtain the AP product of desired particle size distribution directly.The solubility of AP in water at0～80℃is measured and fitted via the Apelblat equation. The influence of various parameters, such as temperature, cooling rate, agitating rate and Na+on the metastable zone of AP in water are investigated by eyes. It is found that the metastable widths of AP decreased with increasing temperature or agitating rate, but increased with increasing cooling rate, the metastable widths of AP increased slightly by adding a little impurity Na+to Raw materials AP.The optimal preparation conditions of five kinds of AP of conventional size are confirmed by studying the effects of the initial concentration, cooling rate, agitating rate, seed and cultivation crystal time on the particle size and the distribution. The main particle sizes of the AP are40-60mesh,60-80mesh,80-100mesh,100-140mesh and140-200mesh, which all conform national military standard GJB617A-2003. Based on preparation technology of AP of conventional size, small-grain AP of mean diameter10μm and particle size distribution1～60μm is prepared by cooling rapidly, increasing agitation and narrowing cooling range.It is found that the drying time of AP extend gradually with the decrease of particle size and vacuum drying can benefit to shorten the drying time compared with the ambient pressure drying. The sensitivity and thermal stability of AP is tested. The strike sensitivity and the friction sensitivity of AP all decrease with the increase of particle size. The thermal decomposition process of AP contain both of the stages of lower and higher temperature range, but the stage of lower temperature range weaken gradually as the decrease of particle size.