Investigation On Ignition And Combustion Of Spherical Magnesium Particles

Magnesium particles have high activity,volume energy density,adiabatic combustion temperature and some other characteristics.Hence they are widely applied in plastic bonded explosives,solid propellants,pyrotechnics and other fields.Since the 1960 s,the ignition and combustion characteristics of magnesium particles have always been the focus of many researchers in the fields of energetic materials.However,the basic research on the ignition and combustion of single micron magnesium particles is still insufficient.In this paper,based on the summary of ignition and combustion of metal particles in different gases at domestic and overseas the ignition and combustion characteristics of single micron magnesium particles in the atmosphere of air are studied.The main work is as follows:(1).A laser ignition experiment system for a single magnesium particle was constructed,and a single magnesium particle stage with hollow structure was designed.The fiber-coupled semiconductor laser can control the energy input during the ignition phase,which is propitious to the establishment of the particle ignition model.The structure of a single magnesium particle and flame and particle temperature is recorded directly with the help of Infrared Thermography Temperature-High-speed microscopy.(2).A continuous laser with a power of 2-4W was used to ignite magnesium particles having a diameter of between 400μm and 1200μm in an air atmosphere.The ignition mechanism of magnesium particles was deduced from the change of magnesium particles morphology and temperature distribution during the laser ignition.The effects of particle size and oxide layer on the ignition delay time and the critical ignition temperature were investigated.The two-dimensional cylinder ignition model was established and the variations of the ignition characteristics parameters were numerically calculated.(3).The combustion mechanism of magnesium particles was analyzed by the change of magnesium particles morphology,flame shape and temperature distribution during the combustion of magnesium particles.The effects of particle size and oxide layer on the combustion temperature and combustion time were studied.The structure and the composition of combustion production were analyzed and the possible chemical reactions upon this stage were calculated through thermodynamic calculations.(4).The ignition and combustion characteristics of magnesium particle-oxidant core-shell micro-clusters were innovatively studied.The mechanisms of ignition and combustion of magnesium particles by different oxidants were investigated.Compared with single magnesium particles,the effect of different oxidants on the ignition and combustion process of magnesium were also analyzed.