油酸包覆纳米铝粉/黑索今复合体系的热行为及非等温分解反应动力学

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

在氮气气氛下,采用油酸(OA)对纳米铝粉(nmAl)进行了表面包覆处理,采用扫描电镜(SEM)、X射线衍射(XRD)和傅里叶变换红外(FTIR)光谱对其形貌和结构进行了表征.用差示扫描量热(DSC)对油酸包覆前后的纳米铝粉与黑索今(RDX)构成的复合体系[nmAl/RDX和(nmAl+OA)/RDX]的热分解反应动力学进行了研究,得到了动力学参数和动力学方程.结果表明,大量油酸以物理吸附的方式吸附在纳米铝粉表面,少量油酸与纳米铝粉表面铝原子发生了化学反应,以化学键合的形式附着在纳米铝粉表面.与nmAl/RDX复合体系相比,(nmAl+OA)/RDX复合体系在不同升温速率下的分解峰峰温都相对降低,分解反应的表观活化能(Ea)和指前因子(A)分别为141.18kJ·mol-1和1012.57s-1,分解反应机理为三维扩散,服从n=1/2的Jander方程,其动力学方程为dα/dt=1013.35(1-α)2/3[1-(1-α)1/3]1/2e-16981.0/T.

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 .