Study On Oxidation Heat Release Of High Energy And High Density Al-Zr Alloy Fuel

As an important part of solid propellant and fire explosive,the oxidation and combustion performance of metal fuels affect the ignition and combustion performance of propellant to a certain extent.In order to overcome the defects such as high ignition temperature and incomplete combustion of traditional metal fuels,a high-density,completely burned metal alloy fuel is obtained.In this article,Al and Zr are alloyed to prepare Al-Zr alloy fuel with outstanding performance.On the premise of ensuring that its volume energy content is not lower than that of elemental Al powder,both the density and the completeness of oxidation of metal fuel are enhanced,which contributes to improving the specific impulse and energy performance of solid propellant.The flake and powder pure Al₃Zr alloy fuel and high Al₃Zr content Al-40Zr composite fuel are prepared by suspension melting,non-consumable arc melting technology combined with traditional mechanical ball milling method and emerging gas atomization method,respectively.Modern analytical test instruments such as particle size analyzer,X-ray diffractometer,field emission scanning electron microscope,thermogravimetric/differential thermal integrated analyzer（DTA/TG）are used to characterize the prepared alloy fuel.The results show that the alloy powder prepared by the ball milling method is nearly spherical,while that by the gas atomization way has a higher sphericity.Due to the discontinuous two-dimensional growth of Al₃Zr,a large number of steps are observed on the surfaces of the Al₃Zr alloy fuel particles,resulting in the oxidation of Al₃Zr originating preferably from the steps.DTA/TG results indicate that the powdered Al₃Zr undergoes concentrated oxidation exotherm at 970℃and complete reaction at 1300℃,as well as the weight gain up to 61.1%,which is equivalent to its theoretical value,implying that the powdered Al₃Zr provides a lower reaction temperature and a good reaction completeness.Oxygen bomb combustion experiments prove that the flake Al₃Zr can not be ignited and burned in pure oxygen environment but the the mixture of flake and powder can,in which the measured combustion calorific value is slightly higher than that in the powdered Al₃Zr.The Al-40Zr composite fuel is composed of two phases of Al and Al₃Zr,forming a structure of a long slub Al₃Zr matrix with a small amount of Al distributed in the gap,and Al₃Zr is detected on the surface of the alloy powder.The strip Al₃Zr structure promotes the complete oxidation of the Al-40Zr composite fuel.DTA/TG results show that compared with pure Al₃Zr alloy fuel,the oxidation exotherm peak of Al-40Zr composite fuel has a hysteresis of 70℃,indicating that the presence of a small amount of elemental Al in Al-Zr alloy fuel will slightly reduce its concentrated oxidation exotherm temperature.The weight gain of Al-40Zr composite fuel can reach 59.4%at 1300℃,and the reaction can be completed,indicating that Al-40Zr composite fuel also has good reaction completeness.The combustion heat test results show that the volumetric combustion heat of Al-40Zr is as high as 82118J/cm³,which ranges between the data of elemental Al and pure Al₃Zr.The reaction completeness and combustion calorific value of pure Al₃Zr alloy fuel and Al-40Zr composite fuel are superior to the existing elemental Al powder.However,it is difficult to prepare large quantities of pure Al₃Zr alloy fuel.So in practical applications,Al-40Zr rather than pure Al₃Zr should be considered to replace elemental Al powder as a metal fuel and added to the propellan.In short,two kinds of Al-Zr alloy fuels with different Al₃Zr contents have excellent performance,and have broad application prospects in the field of propellants and explosives.