Study On Thermal Explosion Mechanism Of Several Typical Energetic Explosives

Energetic material is a kind of material with high energy density,which can cause explosive reaction under certain external conditions.It has a wide range of applications in military and civil fields.According to its property and use are different,can contain energetic material to be divided into explosive,gunpowder,pyrotechnic medicine and firework medicine to wait,among them in above classification,explosive is everybody the most familiar word,people can contain energetic material in general even is called explosive,but the scientific name of explosive actually is fierce explosive.High explosive has the characteristics of high explosive power,good stability and safe use.Detonation is the main form of explosive explosion,once it is detonated,it will produce a very high detonation speed and very violent explosive power.Among them,RDX has been widely used in the field of mixed explosives and propellants,and HMX is the one with the highest energy and best comprehensive performance among the explosives already used at present.CL20 is a new star of high energy density material,whose detonation velocity,detonation pressure,density and energy density are higher than HMX,and it is a very potential ammonium nitrate explosive.Multi-nitrogen metal-containing high-energy materials,all-nitrogen ultra-high energy density materials will play a huge role in the future in explosives,propellants,rocket propellants and other aspects.The sensitivity of strong explosive is generally low,and it can remain stable in the daily vibration and slight impact.When used,it usually needs the help of initiators to achieve the effect of combustion to detonation.The common initiators are lead azide,dinitrodiazophenol,K.D,GTX and DAP-4.With the development of modern chemical technology,driven by the demand of national defense,the country and people are eager to find new energetic materials and explosives with better performance.The most important thing to find new energetic materials is to find out the decomposition mechanism of energetic materials.Because the energy release process of energetic compounds is complex,experimental exploration is very dangerous.At present,the mechanism analysis in this field is mostly carried out by theoretical simulation method.The main content of this paper is to use CPMD method to simulate the decomposition mechanism of high explosive,and provide ideas for the design of new energetic materials in the future.The first chapter describes the research purpose and significance of this paper,and summarizes the research progress of high explosive and initiator.The second chapter introduces the theoretical basis and calculation method.The third chapter to the fifth chapter is the main research work during my master’s degree.Among them,In the third chapter,the combustion to detonation paths ofα-RDX andε-CL-20 in condensed matter are simulated by CPMD method.According to the previous summary,α-RDX andε-CL-20 have similar initial decomposition pathways,namely the breaking of the N-NO₂bond.In this paper,the decomposition mechanism ofα-RDX andε-CL-20 under the condition of temperature rise has been described in detail and systematically.The mechanism of hydroxyl radical transfer and the influence of radical on the process of combustion to detonation have been demonstrated.Various phenomena in the thermal decomposition experiments have been explained.In the fourth chapter,the complex of dipentazolium iron,a representative recent total nitrogen complex,is taken as the research object,and its special plane structure characteristics and decomposition mechanism are analyzed.Pentazolium salt compounds generally release a great deal of energy in the explosion,and the main product is the small,environmentally friendly molecule N₂.It is well known that ring N₅^-and C₅H₅^-are isoelectronic bodies,as are iron dipentazole and ferrocene.However,in most of the metal complexes of pentazole,ring N₅^-always forms aσbond with metal cations,which is obviously different from the classical ferrocene configuration in which metal cations form aΠbond with ferrocene.Therefore,we designed the Fe（η⁵-N₅）₂and Fe（N₅）₂structures formingΠbond andσbond respectively,and studied the ligand structure,binding energy,coordination pathway and decomposition mechanism between them and ferrocene by using DFT and CPMD calculation methods.In the fifth chapter,research is based on four（H₂dabco）[M（Cl O₄）₃]cations designed by Sun Yat-sen University,in which H₂dabco H₂dabco²⁺is1,4-diazabicyclo[2.2.2]octane-1,4-diium,M is Na⁺,K⁺,Rb⁺,NH₄⁺,which named as DAP-1,DAP-2,DAP-3,DAP-4.DAP-4 has attracted extensive attention as the only metal-free energetic compound.Metal-free energetic materials generally have the advantages of high gas production rate and no metal residue after combustion or explosion.The similar explosive performance of CL-20 makes it widely used in explosives and propellant components.However,the detonation mechanism of metal-free perovskite energetic compound DAP-4 has not been reported.However,the detonation mechanism of DAP-4 has not been reported.Therefore,we took metal-free molecular perovskite high-energy material（DAP-4）as the research object,firstly analyzed its electronic structure,and then performed CPMD simulation on DAP-4 at 300-2500 K.Through simulation,its stability was proved,and its decomposition mechanism was summarized.