Thermal Behavior and Non-Isothermal Decomposition Reaction Kinetics of Aluminum Nanopowders Coated with an Oleic Acid/Hexogen Composite System

Abstract

Aluminum nanopowders(nmAl)coated with oleic acid(OA)were obtained under nitrogen atmosphere,and their surface morphologies and structures were characterized by scanning electron microscope(SEM),X-ray diffraction(XRD),and Fourier transform infrared(FTIR)spectroscopy.The thermal decomposition reaction kinetics of composite systems,nmAl/hexogen(RDX)and(nmAl+OA)/RDX,were investigated using differential scanning calorimetry(DSC).Their kinetic parameters and kinetic equations were obtained.The results showed that most of the OA adsorbed on the aluminum nanopowder surface by physical adsorption.Only a small amount of OA reacted with the surface aluminum atoms and adhered to the surface via chemical bonds.Compared with the nmAl/RDX composite,the peak temperatures for the (nmAl+OA)/RDX composite at multiple heating rates were lower.The apparent activation energy(E a )and pre-exponential factor(A)of the main decomposition reaction were 141.18 kJ·mol -1 and 10 12.57 s -1 .The reaction mechanism fits a three-dimensional diffusion mechanism and obeys the Jander equation with n= 1/2.The kinetic equation can be expressed as:dα/dt=10 13.35 (1-α) 2/3 [1-(1-α) 1/3 ] 1/2 e -16981.0/T .