Study on Shock Compression Behavior of Active Metal Powders

Author:Cui Nai Fu

Supervisor:chen peng wan


Degree Year:2017





Active metal powders can react to generate new products with strong exothermic process under the action of shock wave.The intermetallic compound can be synthesized by shock treatment of active metal powders.The active metal powders can be used in explosive charge and warhead material to improve the damage effects by using their reactivity and high exothermicity.In order to make the active metal powder can be applied to the explosion impact and damage process,it is necessary to study the shock compression behavior of the active metal powders in depth.In recent years,this research has been paid more and more attention.In this paper,shock compression behavior of Ti+Si active metal powders with high exothermicity were studied.The active metal powders with different particle size and chemical ratio were ball milled and pressed into ignots with different porosity.The ignots were impacted by different shock loading devices,and the recovered samples were analyzed by XRD and SEM,the photocatalytic properties of the recovered samples were characterized.The self-propagating reaction process of the Ti+Si active metal powders was observed.Different testing methods such as the probe,optical fiber and high-speed camera were used to measure the propagation of shock waves and the induced self-propagation reaction.The experimental results show that when the flyer velocity is 2.52 km/s and Ti:Si=5:3(molar ratio),the reaction product contains Ti and Si;when the fiyer velocity increased to 3.07 km/s,the 5Ti+3Si powders fully react to form the desired product Ti5Si3.When Ti:Si=1:2(molar ratio)and the flyer velocity is 3.07 km/s,the reaction product contains Ti,Si and Ti5Si3;When the flyer velocity increases to 3.37km/s,the Ti+2Si powders react completely to form the desired product TiSi2.The results also show that the formation threshold of Ti5Si3 is lower than TiSi2.In addition,the addition of strong oxidizing agent NH4ClO4 in 5Ti+3Si active powders can synthesize complex photocatalyst with better photocatalytic effect.The experiment results show that the active powders can take place self-propagating high-temperature synthesis(SHS)reaction by plane and cylinder shock loading.In order to observe the self-propagating reaction process induced by shock wave,a two-stage gas gun was selected to apply shock wave loading of Ti+Si powders.High speed camera,probe,and optical fiber were used to measure the velocity of shock waves and combusition waves.The experimental results show that the shock wave propagates in the active powders at a velocity of 0.5-1.0 km/s and decays rapidly and the combustion wave in the active powders propagates at a low velocity of a few centimeters per second.According to control the initial density of Ti+Si and Ni+Al active metal powders and shock strength to obtain the active metal block with little or no reaction and high consolidated degree.The results show that the shock reaction threshold in the 5Ti+3Si powders is rather low.When the initial pressing relative density is 61%,and shock pressure is 11GPa,a high compact density of 97%is achieved for the consolidated 5Ti+3Si block with no reaction.In the consolidation process of Ni+Al powders,the Ni+Al block with a compactness of 100%and without reaction is achieved under moderate shock pressure of 4GPa.