Experimental Study On Explosive Characteristics Of Metal Combustion Agent

Metallic combustion agents were widely used in the high-energy solid energetic materials as an important component,which effective to increase the combustion heat and the energy density of the solid energetic materials.And the solid metal oxide particles generated by combustion can also inhibit the shock combustion.In order to evaluate safety of metallic combustion agents,the explosive properties of metallic combustion agents was studied with metal hydride(MgH2)in this dissertation.The specific research contents and conclusions are as follows:The combustion calorific value and combustion rate of Al,B,MgH2 and mixed metal powders were studied by combustion heat experiment.The results showed that the combustion calorific value of boron B was only half of Al and MgH2,and its combustion rate was much lower than that of A1 and MgH2.When the content of MgH2 increased from 10%to 30%,the combustion calorific value and combustion rate of B-MgH2 increased by 116.37%and 140.34%respectively,while the increase of B-Al was only 52.05%and 67.39%.With the decrease of B content,the combustion calorific value of Al-B-MgH2 increases first and then decreases,but its combustion rate is increasing.In addition,when the content of B is constant,the higher the content of MgH2,the higher the combustion calorific value of Al-B-MgH2 and the higher combustion rate.The minimum ignition energy(MIE)of Al,B,MgH2 and metal mixture were studied by Hartmann tube test system.The results indicated that the MIE of Al and MgH2 were 80-1 OOmJ,10-20mJ,and B was greater than 1000mJ,so the reaction activity of A1 and MgH2 is much higher than that of B.With the increase of MgH2 content from 10%to 30%,the MIE of Al-MgH2 and B-MgH2 decreased from 5070mJ and above 1000mJ to 10?20mJ and 480-500mJ,respectively.The influence of MgH2 content on B-MgH2 was greater than that of Al-MgH2.The MIE of Al-B-MgH2 reduced with the decrease of B content,and when the content of B was constant,the higher the content of MgH2,the smaller MIE of Al-B-MgH2.The dynamics of flame propagation of Al,B,MgH2 and its mixture were studied by a flame cloud propagation test system using high-speed photography and thermal imager.The results indicated that the maximal flame propagation velocities of Al and MgH2 reached 126.1m/s and 604.6m/s at 18ms and 12ms after ignition,and the highest temperature of 837.7?and 1066.7? respectively.With the increased of MgH2 content from 10%to 30%,the flame propagation velocity and maximum temperature of Al-MgH2 were rose 289.4 m/s,844.5? to 593.1 m/s,1052.1?.Moreover,with the decrease of B content and the increase of MgH2 content,the flame propagation velocity and highest temperature increased accordingly.But the lower the MgH2 content,the lower the maximum temperature.The maximum explosion pressure(Pm)and explosion index(Kst)of Al,B,MgH2 and its mixtures were studied by 20L explosion test system.Results indicated that Pm and Kst of Al,B,MgH2 are first increased and then reduced with the increase of the dust concentration,and the Pm and Kst sequence for MgH2>Al>B.MgH2 can improve the value of Pm and Kst of Al-MgH2 and B-MgH2 in different degrees.With the increase of MgH2 content,Pm and Kst of Al-MgH2 is also increased,however,B-MgH2 are opposite.