Preparation Of Aluminum Powder Energetic Composite Material With Spray Method

In this paper,three energetic composites thermites,propellant composites and aluminized explosives were prepared with spray drying method.The advantages of spray drying method were evaluated in the aspects of the structure and sample properties.Compared with the physical mixing method,the performance of the sample prepared by spray drying method has been improved greatly in terms of burning rate,heat release and constant volume combustion.The main research contents were as follows:（1）Thermites Al/KIO₄ were prepared by spray drying method and physical mixing method respectively.Al/KIO₄ by spray drying（sd-Al/KIO₄）has a nano-sized core-shell structure and calorific value of 1262 J/g.The sample sd-Al/KIO₄ reached temperature of 1086.4℃in 0.95ms and the temperature increasement rate is 774.53℃/s by the infrared temperature measurement experiment.Meanwhile,Pmax reached at the rate of 1.65 GPa/s in 4.5 ms during the constant volume combustion experiment.sd-Al/KIO₄ and pm-Al/KIO₄ moisture absorption rates of were 0.60%and 0.89%respectively.sd-Al/KIO₄ had a higher burning rate of 951 m/s due to its loading density.100 mg sd-Al/KIO₄ detonated passivated RDX successfully with a lead plate aperture of 9.2 mm under 10MPa charge pressure pmile pm-Al/KIO₄ couldn’t detonate RDX at the same situation.（2）Iron nitrate composite particles were prepared by spraying method and then the porous Fe₂O₃ nanoparticles were obtained by calcination.The Fe₂O₃ particles prepared at 600℃had the best catalytic activity for AP,and the decomposition peak of high temperature decreased from 403.59 to 320.60℃,and decreased by 82.99℃.The heat release increased from 794 J/g to 3466 J/g while it was faster 3.36 times than that of normal AP.（3）Al/AP composites with oxygen balance（OB）of 10,5,0,-5 and-10 were prepared by spraying method.By constant volume combustion test,the optimum ratio of OB=10 was determined for sd-Al/AP composite material and P_max was 20.56 MPa.As for the Al/AP/RDX composites,the step-up rate was 9.25 GPa/s and it reached the peak within 2 ms.The combustion temperature can reach 1314℃pmile the heating rate was 5155℃/s.P_max was25.37 MPa in the boosting time 0.67 ms while the boosting rate was 12.37 GPa/s.The burning rate could reach 163.03 m/s when charge density 2.1 g/cm³.（4）Al/RDX and Al/HMX were prepared by spray drying method respectively.It could be observed that most of the Al powder was embedded in RDX or HMX and core-shell structure were gotten.The ratio of 3:1,2:1,1:1,1:2 and 1:3 were compared and then the optium ratio was deterimined by the constant volume combustion experiments.P_max was 3.37Pa and the boost time is 4.3μs with the ratio of 1:2.The pressure raising rate is 707.81 MPa/s and the heat release is 723 J/g.It was concluded that the endothermic peak and exothermic peak decreases with the increase of Al powder content gradually.Al/RDX/PVDF and Al/HMX/PVDF composites were prepared by adding PVDF.The maximum combustion heat for these two composites were 7396 J/g and 6293 J/g respectively pmile the Al powder was 3μm.As for the compact sensitivity,the explosion probability of Al/RDX/PVDF and Al/HMX/PVDF were 48%and 24%respectively at the height of 56.5 cm.