Preparation And Application Of Fe-Al Intermetallic Compound Nanoparticles

Aluminum nanoparticles have the advantages of high activity,high heating value,abundant source,and low cost,which can be used as a metal additive in solid propellant to improve specific impulse,reduce pressure index and characteristic signal.However,Al₂O₃easily formed on the surface of nanoparticles due to high surface activity,which is too dense to hinder the further oxidation of the active aluminum inside the particles,thus limiting the release of energy.In this paper,Fe was added into Al by the flow-levitation method to form Fe-Al intermetallic compound nanoparticles,to improve the reactivity of Al nanoparticles.By improving the wire supply system,induction heating coil,and powder collection system,the stability and the yield of powder preparation improved.Fe-Al intermetallic compounds with Fe/Al atomic supply ratios of 1:1,3:7,and 7:3 were prepared by using an improved F-L method.The influence of molten ball temperature on the phase composition of Fe-Al intermetallic compounds was explored.Besides,the relationship between process parameters and metal powder particle size was also investigated.The nanoparticles were characterized by XRD,SEM,TEM,EDS,and XPS.These results show that the Fe-Al intermetallic compound nanoparticles formed.Moreover,the phase composition depends on the supply ratio of wire and the melting temperature.Nanoparticles are spherical,iron and aluminum elements uniformly distribute in the spherical particles.The average particle size can be adjusted by changing the parameters.At the same time,the surface oxygen content of the nanoparticles is high,which is composed of oxidizing phases containing iron and aluminum.It indicates that Fe-Al intermetallic compound nanoparticles have high oxidation activity.Compared with the thermal properties and combustion properties of Fe-Al intermetallic compounds were prepared at different supply ratios of wire.The results show that the Fe-Al nanoparticles containing the Al-rich phase release more heat,and the peak of heat release is sharper.The combustion performance test found that the burning rate of Fe-Al nanoparticles was faster than that of Al nanoparticles.And the burning rate tended to accelerate with the increase of Fe content.Then,compared with the Al nanoparticles made by the F-L method,The oxidation kinetics,oxidation products,storage aging properties,and compatibility were studied and analyzed.The results show that the kinetic parameters Ea and A of metal powder decrease with the increase of Fe content,which improved the powder activity and made the reaction more easily.After annealing and oxidation at 1200℃,the unoxidized Al phase exists in the oxidation products of Al nanoparticles,while only Al₂O₃and Fe₂O₃oxides exist in the 10at.%Fe and 20at.%Fe iron aluminum nanoparticles.In the 60-day aging test,the oxidation degree of 10at.%Fe iron aluminum nanoparticles are higher than that of Al nanoparticles,showing a higher oxidation activity,which further proves that the addition of Fe improves the oxidation activity of nanoparticles.However,through the compatibility test of metal powder and HTPB suspension,it was found that the viscosity of Fe-Al nanoparticles/HTPB suspension increased compared with that of Al nanoparticles,so the addition amount of Fe-Al nanoparticles should be appropriate.