| In theory,the combustion heat release of boron powder is higher than that of aluminum powder and magnesium powder.As a high-energy component additive,boron powder is used in the field of mixed explosives,pyrotechnics and solid propellants.However,compared with other metal powders,the energy effect does not reach the theoretical expectation.The main reason is that after the boron particles are heated and burned,there is a molten oxide film mainly composed of B2O3 on the surface,and its three-dimensional network structure is wrapped on the surface of boron particles,which hinders the penetration and diffusion of oxygen to boron particles in the air,and makes the oxidation reaction between boron particles and oxygen unable to be fully carried out.How to improve the reaction completeness and energy release of boron powder in energetic materials has become a key problem in the field of energetic materials.In the process of ignition and combustion of boron particles,F atoms are introduced to react with the oxide film on the surface of boron particles to generate BF3 gas,which can effectively improve the removal rate of oxide film,enhance oxygen permeation and diffusion,increase heat release,improve the combustion efficiency of boron particles,promote the oxidation reaction of boron particles,reduce the first stage combustion time,and improve the release of total energy.The F atoms on the fluorographene(FG)layer were used to explore the effect of improving the combustion efficiency of boron particles.The results show that the introduction of F atoms in the ignition and combustion process of boron particles can produce BF3 gas by chemical reaction with the oxide film on the surface of boron particles,which can effectively improve the removal rate of oxide film,enhance oxygen permeation and diffusion,improve the heat release,improve the combustion efficiency of boron particles,promote the oxidation reaction of boron particles,reduce the first stage combustion time,and improve the release of total energy.In this paper,the F atoms on the fluorographene(FG)layer were used to prepare FG / Boron Composite energetic materials,and the effect of FG on the combustion efficiency of boron particles was investigated.The fluorinated graphene(FG)solution with few layers was prepared by using graphite fluoride as raw material.The 2 ? m crystal boron powder,20 ? m,5 ? m,500 nm amorphous boron powder were coated by solvent evaporation method to form composite materials.The above composite materials were tested by SEM,DTA,FTIR to explore the optimal coating ratio.The influence of different coating ratio on the exothermic peak of boron powder chemical reaction,and the influence of different coating ratio on the initial oxidation,termination oxidation and maximum decomposition temperature of the composite were studied.The exothermic heat of the composite under the optimal coating ratio was measured by oxygen bomb calorimeter.(1)The FG was prepared by high-speed shear method.The results of SEM,TEM,AFM and FTIR showed that FGS can be prepared by high-speed shearing and stripping in aqueous solution with sodium cholate.The ratio of graphite fluoride to NAC is 3:1,the rotational speed is 9000r/min,the shear time is 8h,the concentration of FG is about 0.082mg/ml,and the number of layers is about 2 layers.(2)The ignition combustion model of boron particles in c/h/o/n/f environment is summarized.The advantages and effects of the introduction of F atoms in the ignition and combustion stages of boron particles are discussed.(3)The FG deionized water solution was mixed with anhydrous ethanol solvent in a ratio of 1:4,heated and stirred with magnetic stirrer,the temperature was controlled at about 70 ° C,and the rotational speed was controlled at 300r/min.The amorphous boron powder of 2 ? m crystal,20 ? m,5 ? m and 500 nm was coated by solvent evaporation method.The products were characterized by SEM,DTA and FTIR.(4)FG and 2 ? m crystal boron powder,20 ? m,5 ? m and 500 nm amorphous boron powder formed composite materials.According to DTA test results,the optimum coating ratio was determined to be 40%,40%,20% and 30%,respectively.The heat release of composite materials was measured by oxygen bomb calorimeter,and the combustion heat of composite was increased by 53%,56%,69% and 224% respectively.(5)It is found that the smaller the particle size is,the larger the surface contact reaction area is,and the better the effect on improving the combustion heat of boron particles is.The chemical reaction exothermic peak of boron powder oxidation occurs in advance,and the initial oxidation temperature occurs in advance with the increase of FG coating proportion.Among them,the combustion heat of 500 nm amorphous boron powder is the best,and the initial oxidation temperature of the exothermic peak of the main chemical reaction is also advanced. |
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