Preparation And Properties Study Of Ultrafine Metal Ferricyanide/Ammonium Perchlorate Composite Particles

Ammonium perchlorate(AP)is the most common oxidant used in composite propellants,and its thermal decomposition process has a great impact on the entire combustion process of the propellant.However,conventional ultra-fine ammonium perchlorate particles have many irregular shapes with corners,high mechanical sensitivity and have characteristics of easy moisture absorption and agglomeration,which limit the application of ammonium perchlorate in solid propellants.In order to solve above problems,nano-metal ferricyanide is prepared via coordination homogeneous precipitation method and hydrothermal synthesis method,and then ultrafine spherical M₂Fe(CN)₆/AP composite particles are prepared by a solvent non-solvent method and jet milling method.The morphology,particle size distribution,crystal type,the thermal decomposition performance,the anti-agglomeration performance,the powder flow characteristic,the mechanical sensitivity and the bulk density of ultrafine spherical M₂Fe(CN)₆/AP composite particles are tested,analyzed and discussed.The nanometer M₂Fe(CN)₆ is also applied to the composite propellant to explore the effect on the burning rate and mechanical properties.The main works are as follows:First,Optimum preparation of nanometer M₂Fe(CN)₆ by coordination precipitation and hydrothermal synthesis are studied.The final prepared nano-Cu₂Fe(CN)₆ has a spherical shape with a particle size of about 80 nm,and the nano-Pb₂Fe(CN)₆ has a cubic shape with a particle size range of 200-500 nm,and there is no agglomeration among the nanoparticles,the particle size distribution is uniform,and the crystal shape is better.Second,the optimal synthesis conditions for the preparation of ultrafine spherical M₂Fe(CN)₆/AP composite particles by solvent non-solvent method and jet milling method are studied.Finally,the ultrafine spherical M₂Fe(CN)₆/AP composite particles prepared by the two methods have a quasi-spherical shape,uniform particle size distribution with size about 5?m and there is no agglomeration among ultrafine spherical particles.At the same time,all the nanometer M₂Fe(CN)₆ are uniformly composited on the surface of the ultrafine AP without traces of shedding.Then,the thermal decomposition,powder flow performance,mechanical sensitivity and et.al of M₂Fe(CN)₆/AP composite particles are tested and analyzed.The nano-Pb₂Fe(CN)₆ and Cu₂Fe(CN)₆ in the M₂Fe(CN)₆/AP composite particles can decreased the high-temperature decomposition peak temperature of AP from the original 411?to 360?and 323?,the high-temperature decomposition activation energy Ea reduced by 14.2%and 10.4%,the rate constant k increased by 28.6 times and 9.5 times,respectively.Compared with ultrafine AP of the same particle size,nano-M₂Fe(CN)₆ can effectively alleviate the agglomeration of AP.The flow factors ff of ultrafine spherical AP,ultrafine spherical Cu₂Fe(CN)₆/AP composite particles,and ultrafine spherical Pb₂Fe(CN)₆/AP composite particles are 1.27,1.15,1.19,respectively.Which proves the fluidity has improved.The bulk packing density has increased by 2.4%,11.7%,14.0%,and the tapped bulk density has increased by 5.7%,8.0%,and 11.5%respectively.The impact sensitivity has reduced by 21.8%,25.6%and 35.3%.The friction sensitivity has decreased by 41.7%,33.3%,and 50%,respectively.Finally,the application of M₂Fe(CN)₆ in the composite propellant shows that the burning rate of composite propellant containing 3%metal ferricyanide catalyst is about 2.6 times faster than the burning rate of composite propellant without burning rate catalyst.The burning rate of solid propellants using Cu₂Fe(CN)₆ as the burning rate catalyst is slightly better than Pb₂Fe(CN)₆.At the same time,the tensile strength and the elongation at break of the composite propellant with 3%Cu₂Fe(CN)₆ catalyst is superior to the 3%Pb₂Fe(CN)₆catalyst at any temperature.