Experimental Study On Shock Ignition Characteristics And Transient Raman Spectra Of Liquid Energetic Materials

Energetic materials have a very wide range of applications and important significance in modern military and national defense and civil construction,and they are also an important measure of a country's military power.At present,the application of energetic materials has a history of hundreds of years,but there is still a lack of some basic researches on them,especially the researches on its energy release mode,detonation mechanism and other micro-level researches.The shock-induced ignition and detonation mechanism of energetic materials have always been one of the important scientific issues to be deeply understood in the fields of mechanics of explosion,detonation physics,materials science and condensed matter physics.Ignition and detonation reaction in energetic materials is a very complicated process of high temperature and high pressure,during which there may be various intermediate stages,phase transitions,and quickly release of energy in time scale of nanoseconds.These are the challenges to be faced in the shock response study of energetic materials.In this work,the two-stage gas gun was used as a dynamic loading tool combined with photoelectric probe,optical radiation detection technology,and transient Raman spectroscopy technology to study the optical radiation history and Raman spectra of two typical liquid energetic materials(Hydrogen peroxide and nitromethane)under different impact pressure loadings.In addition,we also studied the effect of sensitizers on the impact ignition characteristics of nitromethane.The main results are as follows:First,we designed a target for liquid samples of strong oxidizer and solvent,and obtained the optical radiation history of hydrogen peroxide in shock compression of8.7-15.2GPa and that of nitromethane in shock compression of 10.1-14.1GPa.Secondly,the shock-induced luminescence characteristics and energy release modes of hydrogen peroxide and nitromethane were studied.The critical pressure of shock-induced ignition of hydrogen peroxide was determined to be about 12.8GPa according to whether the ignition luminescence characteristics occur.Different ignition feathers and energy release modes of nitromethane under shock compressions were revealed by the shock luminescence histories.The experimental results of hydrogen peroxide show that there is no ignition reaction happened at the early stage of impact loading at low pressure of 10.3GPa,but a slow energy release phenomena was observed in the later stage,i.e.a slow energy release mode.The twice ignition characteristics and partial energy release were observed during the impact loading of immediate strength of 11.8GPa,i.e.,a partial energy release mode.Under the strong shock pressure of 14.1 GPa,the sample started to glow intensely as soon as the shock wave reached the sample,i.e.,a complete energy release mode.In addition,we found that5%ethylenediamine as a sensitizer significantly reduced the shock-induced ignition pressure of nitromethane.These results are of importance for revealing the shock ignition mechanism of the two liquid energetic materials.Finally,the transient Raman spectrum of hydrogen peroxide was observed for the first time under dynamic loading near 11 GPa,and it was found that the O-O stretching peak was blue-shifted and broadened,but no Raman peak of molecular oxygen was discerned,indicating that the H₂O₂molecules were stable under this pressure.However,further confirmation is needed because of low signal-to-noise ratio.