Molecular reaction dynamics simulation of thermal decomposition for aluminiferous RDX composites

Abstract A newly parameterized reactive force field with low gradient correction (ReaxFF-lg) is used to simulate the thermal decomposition of RDX systems. Pure Al, surface nitrided Al (AlN) and surface oxidized Al (AlO) particles are constructed to mix with RDX. The simulation results indicate that the decomposition mechanism of pure RDX is the elimination of HONO in the initial stage and the elimination of -NO2 in the later stage. The mechanism is further testified by the density functional calculation. RDX molecule adsorbs on the surface of Al particles to form N Al and O Al bonds. N O bond ruptures is the main decomposition ways of aluminiferous RDX in the initial stage. The decompositions of RDX and RDX/AlO need to overcome 2.00 kJ/g and 0.31 kJ/g energy barrier, respectively. However, there are no energy barriers in RDX/Al and RDX/AlN decomposition processes. Aluminiferous RDX decomposition depends on the strong attraction of Al to N and O. Alumina layer blocks the attraction of Al to O and N in RDX, causing the reactivity of AlO declines significantly. However, the Al-nitride layer hardly has such blocking effect, resulting AlN maintains the reactivity of Al.