Effects of aluminum on thermal decomposition of hexogen/ammonium perchlorate

Thermogravimetry-differential scanning calorimetry-mass spectrometry-Fourier transform infrared spectrometry(TG-DSC-MS-FTIR) simultaneous analysis was used to study the effects of 10.7 μm and 40 nm Al on the thermal decomposition of the Hexogen/ammonium perchlorate(RDX/AP, 1/2, mass ratio) mixture. TG-DSC results show that there are two mass loss processes for the thermal decomposition of RDX/AP/Al. The first one is mainly ascribed to the thermal decomposition of RDX. The reaction rate of RDX/AP/10.7 μm Al is so fast that the apparent activation energy, calculated by model-free Friedman method, is negative, which is the same as that of RDX/AP. 30%(mass fraction) 40 nm Al added in RDX/AP change the activation energy from negative to positive value. The second mass loss process of the RDX/AP/Al mixture is ascribed to the thermal decomposition of AP. This process can be divided into three stages for RDX/AP with and without Al. The kinetics model is not changed in the presence of micro-sized Al, while it is changed from CnB/D1/D1 to CnB/D1/D4 after the addition of 40 nm Al to RDX/AP. The reaction rate constant of the first stage and the end temperature of the second stage decrease, while the end temperatures of the third stage increase in the presence of 40 nm Al. The MS-FTIR results show there is a competition between the formation reactions of HNCO, N₂O and NO₂ during the second mass loss process.