The Surface Modification Of Aluminum Powder And Its Application In The Energetic Material

The oxidation of aluminum powder will release a lot of heats and the addition of aluminum powder results in energy enhancement of explosive system and propellant.Besides,aluminum powder is characterized by wide material sources and low cost.Therefore,aluminum powder is widely used as energy booster in thermit,propellant and explosive.However,its disadvantages of the low energy release rate and the low combustion rate are present in practical application,so we modified the surface of aluminum powder to improve its properties.The study in this paper were shown as follows:Firstly,we use the coating agent NC and TNT to coat industrial spherical aluminum powder(d₅₀=13.960 μm),and mechanical chemical method was also used to modify the aluminum powder.The prepared composite particles were characterized by SEM,FTIR,TG-DSC and so on.Through comparative analyses,it is found that the aluminum powder modified by mechanical chemical method has the best performance,which has high thermal reaction characteristics,and is suitable for industrial application.Secondly,the 01-HDDM type stirring ball mill was used to modify the raw aluminum powder and the process of preparing high active flake aluminum powder by mechanical chemical method was also studied:Ball material ratio,grinding aids,solvent,rotating speed and drying methods could affect the modification effect.These parameters were determined by experiments finding.SEM and particles size measurement revealed that raw aluminum powder after ball milling was in the shape of flake and had the narrow distributions of particle size;XRD characterization showed that the crystal form of aluminum powder was not changed in the process of ball milling,but the surface morphology changed;TG-DSC thermal analyzer showed that the flake aluminum powder after ball milling has a high oxidation reaction activity,so aluminum could be oxidized completely and more heat was released.Therefore,the flake aluminum powder can enhance the energy of propellant and explosive.Lastly,the direct method was used to prepare A-IX-Ⅱ aluminized explosives and the morphology,thermal decomposition behavior,impact sensitivity,friction sensitivity and explosion heat were studied.Results had shown that the apparent activation energy of raw spherical aluminized explosives（Alexl）is 113.3 kJ·mol^-1,and the apparent activation energy of flake aluminized explosives（Alex2）is 122.9 kJ·mol^-1（increased by 8.5%）.But compared to the spherical aluminized explosives,the flake aluminized explosives showed better thermal stability.With the addition of flake aluminum powder,the impact sensitivity was increased by 9.1%,while the friction sensiti.vity was decreased by 24%.In contrast to the spherical aluminized explosives(6805 kJ·kg^-1),the explosion heat of flake aluminized explosives is 7246 kJ·kg^-1,and the amount of increasing is 6.48%.That indicated that flake aluminum powder could significantly improve explosion heat and energy.