Study On Explosion Property And Initiation Mechanism Of High Explosive Containing Active Gas

With the continuous expansion of the application field of explosive and the increasingly complex of the use environment,high explosive has always been a research hotspot in the field of energetic materials.Active gas can improve the work capacity of explosive,but it is difficult to change the gas environment in practical application.In this paper,a variety of storage media are used to form uniform or outside active gas in the explosive.The active gas explosive has been comprehensively and systematically studied from three aspects:explosion property,interaction mechanism between active gas and storage medium,and initiation mechanism of active hot spots.Hydrogen-storage glass microballoons were prepared by using hollow structure of glass microballoons.The high-temperature and high-pressure reaction kettle improved the preparation efficiency of hydrogen-storage glass microballoons.The highest hydrogen-storage pressure and the maximum hydrogen-storage capacity of the unbroken glass microballoons were 3.34 MPa and 0.82 wt.%.After hydrogen-storage glass microballoons were mixed with the emulsion matrix,active hydrogen can be evenly distributed in the explosive.Changing the sensitizing gas and increasing the hydrogen-storage pressure can effectively regulate the detonation velocity of emulsion explosive.The combined effect of the two makes the detonation velocity of explosive show a trend of first increasing and then decreasing.The evenly distributed hydrogen in the explosive plays the dual role of sensitizing the emulsion matrix and participating in the detonation reaction,which improves the explosion property of explosive and promotes the energy output of emulsion explosive.Hydrogen increases the peak overpressure and specific total energy by 10.19%and 7.99%,respectively.And the tensile strength of glass microballoons is the limiting factor for the improvement of explosion property.In order to introduce active gas into military explosive,a spiral aluminum tube was used to store high-pressure active gas,which was wrapped around the explosive.Hydrogen and aluminum tube enhance the peak overpressure and energy parameters of explosive,respectively.Hydrogen is used as the intermediate of the reaction,the reaction product changes the ratio of oxidant reacting with aluminum tube,and increases the combustion rate of aluminum.Air explosion experiments show that hydrogen can effectively utilize oxygen in the environment,and it has a better effect on increasing the peak overpressure than in underwater explosion,but the air explosion environment is not conducive to maintaining the combustion of aluminum tube.The active gas aluminum tube has special reaction mode.The aluminum tube is stretched and broken into aluminum fragments,and the fracture of aluminum tube can directly react with the oxidizing gas,reducing the reaction temperature of aluminum and increasing the characteristic length of aluminum that can participate in the explosion reaction.The type of active gas affects the explosion property of explosive.When the active gas is oxygen,the type of oxidant that reacts with the aluminum tube is changed,and the energy parameters of explosive are significantly improved.Anylon container was used to store high-pressure hydrogen or oxygen in the voids between explosive particles,active gas can participate in the detonation reaction of explosive earlier.The effects of active gas on explosion property,energy release rate and thermal decomposition process were studied.Both hydrogen and oxygen can increase the energy release rate of explosive.Oxygen has a better effect on improving explosion property.Oxygen can increase the peak overpressure and specific bubble energy of explosives by 9.84%and 14.89%,respectively.Hydrogen and oxygen have different mechanisms for improving the explosion property of explosive.Hydrogen changes the C/H ratio involved in the detonation reaction,generating more heat and gaseous products.Oxygen enhances the degree of oxidation of explosive molecules,making the detonation reaction more complete.The experimental results of thermal analysis show that hydrogen increases the activation energy and pre-exponential factor of composite explosive,mainly because hydrogen changes the thermal decomposition process of explosive and has excellent thermal conductivity.With the increase of hydrogen content,the effect of inhibiting thermal decomposition of explosives is more obvious,and the results of critical temperature of thermal explosion show that hydrogen improves the thermal stability of composite explosive.The initiation mechanism of explosive containing active hot spots is studied by theoretical calculation and molecular dynamics simulation.The theoretical calculation results show that compared with nitrogen bubble and oxygen bubble,hydrogen bubble has a higher temperature rise rate under adiabatic compression,but lower temperature extreme.The high-strength glass microsballoons increase the initial external pressure,thereby increasing the temperature rise rate and temperature extreme of bubbles.With the increase of the initial external pressure,the advantage of hydrogen bubble in the temperature rise rate is more obvious.Increasing the initial internal pressure of bubble will resist the adiabatic compression process of hot spots,prolong the formation time of hot spots,and then reduce the detonation velocity of explosive.The molecular dynamics simulation results show that the gas molecules in the void will hinder the acceleration process of explosive molecules upstream of the void,but will connect the upstream and downstream explosive molecules faster,making the void closed for chemical reaction.In addition to heat transfer to the surrounding explosives,the oxygen hot spots also increase the chemical reaction process between oxygen molecules and explosive molecules.The exothermic heat of the chemical reaction enhances its heating effect on the surrounding explosives.Increasing the impact velocity is conducive to improving the heating effect of hot spots and promoting the reaction between oxygen molecules and explosive molecules.The main products in the area of hot spots change from nitrogen oxide to nitrogen oxide and hydroxide.The final product H2O will be produced during the formation of hot spots.The active hot spots accelerate the detonation reaction process of explosive.