Preparation And Properties Study Of Spherical Ultrafine Ammonium Perchlorate And Its Composite Particles

In order to improve the thermal decomposition and moisture absorption of ammonium perchlorate(AP)and improve the dispersion of nano combustion catalyst,ultrafine spherical AP with controllable morphology and particle size was prepared by recrystallization method,and it was compounded with nano CuO to form ultrafine quasi spherical CuO@AP particles.Finally,it was applied to AP/HTPB composite solid propellant.The research contents of this paper are as follows:Firstly,ultrafine spherical AP was prepared by solvent-nonsolvent recrystallization method.The effects of various factors on the morphology and particle size of recrystallized AP were explored.The optimum process for preparing ultrafine spherical AP by recrystallization method was: NMP-dichloromethane system,magnetic stirring rate was 1000 rpm,dropping rate was 1m L/min,crystallization temperature was 20 ℃,and the volume ratio of NMP to dichloromethane was 1: 10.Then the moisture absorption,thermal decomposition and sensitivity were tested.The results show that the peak temperature of high temperature decomposition of ultrafine spherical AP is 4.89 ℃ higher than that of raw AP,that is,the thermal stability is improved;the moisture absorption rate is 20.59% and 52.63% lower than that of raw AP and ultrafine AP with the same particle size,indicating the moisture absorption performance is improved;the impact sensitivity is 53.74% higher than that of raw AP,62.51% lower than that of ultrafine AP with the same particle size,which indicates the mechanical sensitivity is reduced,and the safety performance is improved.Secondly,CuO@AP was prepared by solvent-nonsolvent recrystallization method.The effects of different factors on CuO@AP particles were explored.The optimum process conditions were determined as follows: the stirring rate was 1000 rpm,the dropping rate was 1m L/min,the volume ratio of NMP to dichloromethane was 1: 10,and the surfactant SDBS was added.The thermal decomposition and sensitivity properties were tested and compared with the mixture of CuO and ultrafine AP(CuO/AP).The results show that compared with CuO/AP,the peak temperature of high temperature decomposition of CuO@AP was reduced by 19.27 ℃,and the reaction rate constant was 1.19 times higher,indicating that the catalytic performance is further improved,and the thermal decomposition reaction is accelerated.The impact sensitivity is 41.23% lower than that of CuO/AP,indicating the safety performance is improved.Finally,ultrafine AP,ultrafine spherical AP,CuO/AP mixture and CuO@AP with coreshell structure were applied to AP/HTPB solid propellant,and the thermal decomposition,sensitivity and mechanical properties were studied.The results show that the apparent activation energy of ultrafine spherical AP propellant was 8.16% lower than that of ultrafine AP propellant,and the rate constant increases by 13.64%.The activation energy of CuO@AP propellant is 23.63% lower than that of CuO/AP propellant,and the rate constant increases by172.7%,indicating that the ultrafine spherical AP,CuO/AP and CuO@AP significantly improve the thermal decomposition properties of AP/HTPB propellant.Otherwise,the catalytic effect of CuO@AP is obviously better than that of CuO/AP.The impact sensitivity of ultrafine spherical AP propellant is 29.61% lower than that of ultrafine AP propellant,and the elongation at break is increased by 40.98%;the impact sensitivity of CuO@AP propellant is 25.38% lower than that of CuO/AP propellant,and the elongation at break increases 56.50%.The results above show the impact sensitivity and mechanical properties of AP/HTPB propellant prepared by ultrafine spherical AP are better than that added with ultrafine AP,and the impact sensitivity and mechanical properties of CuO@AP propellant are better than those of CuO/AP propellant.