Influence Of Al And Al₂O₃ Nanoparticles On The Thermal Decay Of Energetic Materials:Reactive Molecular Dynamics Simulations

The chemical reaction mechanism of aluminum matrix composite energetic materials under extreme conditions is complex,so it is an enormous challenge to study the coupling process between chemical reaction and physical change.In this paper,the thermal stability and reaction mechanism of ANP(Al nanoparticle)and its oxides on the thermal decomposition of energetic materials were studied by means of reaction molecular dynamics simulation.With ANP and RDX,TATB,NG,CL-20 as the research object,exploring the particle size,content of ANP,aluminum oxide,temperature can to energetic materials such as thermal decomposition,the influence of Al-containing clusters is analyzed emphatically and evolution mechanism of C-containing clusters,discovered the microexplosion of ANP process and dispersed reunion,reveals the energetic materials and the reaction mechanism of ANP.The main research contents of this paper are as follows:(1)The Al/RDX model was constructed by means of reaction molecular dynamics,and the influence of ANP and its oxides on the thermal decomposition of RDX was studied.It was found that the addition of ANP significantly increased the release of heat from combustion,while reducing ignition delay time and reaction barrier.However,the bimolecular catalytic decomposition reaction was dominant in Al/RDX system and RDX system,and intermediates played an important role in the thermal decomposition of energetic materials.Temperature plays an important role in the decomposition of RDX,and ANP and its oxides have an obvious catalytic effect on the thermal decomposition of RDX at low temperature.As an important product of Al-containing explosives,the mass and quantity of clusters are also affected by temperature.Although Al contributes little to energy release,similar surface catalytic effects have been found at low temperatures.Especially under the condition of program heating and adiabatic heating simulation,the catalytic effect of ANP and its oxides on the decomposition of RDX is remarkable.(2)The reaction mechanism of ANP with TATB with different particle size and content was studied.It is found that the content and particle size of ANP affect the energy release of Al/TATB system,and the appropriate ANP will significantly promote the energy release of Al/TATB system.The addition of ANP will reduce the formation of gaseous small molecule products.Due to the insufficient oxygen content of the system,Al-C and Al-N bonds are formed in addition to Al-O bonds during the process of ANP bonding with TATB.The dynamic analysis of the morphology of ANP shows that the micro-explosion effect and the dispersion and agglomeration effect are determined by the particle size and content of ANP.The mechanism of action of alumina thin films in the thermal decomposition of TATB and the reaction mechanism of O and Al bidirectional transmembrane transport were proposed.(3)The reaction mechanism of np with NG and CL-20 in the process of programmed heating was studied.According to the potential energy change and product evolution of Alcontaining system,the influence of ANP on thermal decomposition of energetic materials(NG,CL-20)with poor thermal stability was obtained.It was found that the ANP changed the initial decomposition path of NG and CL-20,which reduced the thermal sensitivity of NG to some extent,but increased the thermal sensitivity of CL-20.The cluster growth mechanism of ANP was studied by cluster analysis.Based on the trajectory analysis and mass evolution,the slow oxidation mechanism of ANP was proposed.With the increase of temperature,the oxide layer became thicker and thicker,which inhibited the melting and dispersion mechanism of ANP.