The Preparation And Performance Of Insensitive Ultrafine Quasi-spherical Ammonium Perchlorate By Airflow Smash

Research of the high-burning-rate and insensitive propellant is an important direction of solid rocket propellant,and the use of ultrafine ammonium perchlorate(AP)as the oxidant of solid propellant is a way to achieve it.However,the mechanical sensitivity and hygroscopicity of ultrafine AP increase obviously along with the decrease of particle size,which seriously affect its application in the high combustion speed propellant.Therefore,it is particularly important to reduce the sensitivity and hygroscopicity of superfine AP and improve its safety.The research shows that the spheroidization of AP can help to reduce its mechanical sensitivity and improve the comprehensive performance.In this paper,the superfine spherical AP particles were prepared by two methods which are ultrasonic spray crystallization and pneumatic jet milling.In the end,it is determined that the ultrafine spherical AP can be prepared in bulk by current of air smash method.Meanwhile,the performance comparison between the prepared ultra-fine spherical AP particles and the same size non spherical AP particles was carried out,and the application performance of the ultrafine spherical AP and flake Al hybrid system was investigated.The major research contents are as follows:Firstly,the ultrafine spherical AP particles with a particle size of about 10 ?m had been successfully prepared by the ultrasonic spray crystallization method.The process conditions are as follows:water as solvent,tert butanol as non solvent,solvent temperature controlled at 45 ?,and AP saturated solution sprayed into non solvent by ultrasonic spray device.It was proved that the granularity effect is not good.And then study on the preparation technology of ultra-fine spherical AP by the improved air pulverizer was choosed,and micron spherical AP with regular morphology and uniform particle size were successfully prepared.The best process conditions are:the temperature is controlled in 25?30?,the relative humidity is 45?60%,the crush pressure is 0.4 MPa,the feed pressure is 0.6 MPa,the feeding speed is 100 g/min,the height of feeding pipe is 10 mm,the spray ring is double row of 36 holes,AP is smashed once and grinded 8 times.Secondly,the morphology,particle size distribution,specific surface area,crystal form and purity,stacking density,thermal decomposition property,moisture absorption and anti caking properties,impact sensitivity and f-riction sensitivity of ultrafine spherical AP particles prepared by current of air smash method were studied.The results show that morphology of the ultrafine AP is substantially spherical and the product has high purity.The average particle size is about 2 ?m.While compared with the non spherical size of the same particle size,the surface area of ultrafine spherical AP decreases,the bulk density increases,the decomposition peak of high temperature is lagged behind,the moisture absorption and anti caking properties are improved,and the impact sensitivity and friction sensitivity decrease.Last,the thermal decomposition,mechanical sensitivity and burning rate of the superfine spherical AP/Al powders with different morphologies were compared.The results show that The results show that the catalytic effect of spherical A1 on AP is stronger than that of flaky Al and the mechanical sensitivity of the superfine spherical AP/flake A1 system is lower than that of the superfine spherical AP/spherical Al.Meanwhile,the burning rate of propellant can be improved effectively by flake Al.