Study On Low Hygrothermal Aging Of Al/Zr/KClO₄

Electric squibs as a kind of important initiating explosive device,is widely used in weapon system and aerospace field.In the structure,the electric squibs is mainly composed of electrothermal bridge wire,ignition powder,main charge and shell.When energized,the bridge wire heats up to transfer heat to the surrounding ignition agent,ignition agent heated chemical reaction,resulting in heat transfer to the adjacent area,resulting in a violent reaction of the entire mixture The aging performance of the electric squibs directly determines the reliability of the electric squibs in long-term storage.As an ignition agent with good ignition temperature and thermal stability,Al/Zr/KClO₄has been used in electric squibs.It is of great significance to master the effect of Al/Zr/KClO₄aging on its thermal decomposition and combustion behavior for the evaluation of storage reliability and performance improvement of electric squibs.In this paper,the mechanism of thermal aging of Al/Zr/KClO₄under low humidity conditions was studied.The thermal analysis technology,X-ray photoelectron spectroscopy（XPS）and scanning electron microscopy-X-ray spectroscopy（SEM-EDS）were used to analyze the change of Al/Zr/KClO₄ignition agent with temperature and time.With the increase of time,some molecules on the surface of KClO₄crystal were degraded to KClO₃and KCl,and the surface of Zr was further oxidized to Zr O₂under the action of heat.Al did not change significantly.Aging did not lead to the change of its morphology.Aging makes the thermal decomposition activation energy and enthalpy of Al/Zr/KClO₄ignition powder decrease.The aging mechanism function of ignition powder was further obtained by fitting the reaction rate,enthalpy value and surface element parameters of each component.It was found that the reaction rate,Zr oxidation and KClO₄degradation could reflect the time and temperature effects of ignition powder aging.The aging mechanism function was n-order reaction,and the aging activation energy was 95.86-128.90 k J/mol.The effect of thermal aging of metal components on the performance of igniter was further revealed.The thermal decomposition behavior and ignition combustion performance of igniter were investigated by oxidizing metal Zr and Al separately,and then preparing ignition agent.Zr oxidation leads to the change of initial thermal decomposition behavior and ignition delay.The kinetic model of Al/Zr/KClO₄thermal decomposition containing three reactions was successfully described,and the contribution of each step to the total reaction was revealed.The increase of Zr oxidation degree leads to the decrease of activation energy and pre-exponential factor of KClO₄decomposition in Al/Zr/KClO₄mixture.In addition,based on the decomposition kinetics,the reaction progress of Al/Zr/KClO₄mixture at high temperature was predicted.The predicted trend of rapid reaction rate increase is similar to the ignition delay time.The slight oxidation of Al has no adverse effect on the ignition agent.The aging kinetics of Zr shows that Al/Zr/KClO₄is relatively stable at room temperature.