Effect of aluminum particle size on the thermal decomposition of RDX

Effects of aluminum powder with particle sizes of 10.7μm, 2.6μm and 40nm on the thermal decomposition of RDX were studied by DSC. The results showed that Al powders with particle size of 10.7μm and 2.6μm had almost no influence on the thermal decomposition of RDX. Al powders with particle size of 40nm promoted the reaction of the first and the second decomposition peaks. With increase of 40nm Al content, the second decomposition peak of RDX was sharply embodied and advanced. With 40nm Al content of 30%(mass fraction), the second decomposition peak covered up the first peak completely and the heat of reaction increased from 600 to 1600 kJ/mol. TG-DTG was used to investigate the effects of the aluminum powders(30% mass fraction) with different particle sizes on the thermal decomposition kinetics of RDX. The results indicated that microsized aluminum powder had no effect on the thermal decomposition kinetics of RDX. The Al powder with particle size of 40nm made the activation energy and pre-exponential factor decrease from 130 kJ/mol and 10 ^11.87 s ^-1 to 94kJ/mol and 10 ^9.97s ^-1 for RDX, respectively. The most probable mechanism functions of the thermal decomposition of RDX and RDX/40nm Al powder were Avrami-Erofeev equations with n=3/4 and n=2/3, respectively, and the reaction mechanism was classified as nucleus and growth.