Researches On Preparation And Combustion Performance Of Dual-functionaized Aluminum Based Ternary Fuel:Al/PFPE/Cu₂O

The traditional aluminum powder used in solid propellants restricts the development of higher burning rate propellants due to its dense Al₂O₃shell around the Al surface and aggregation behavior during combustion.Therefore,it is significant to find functionalized composite aluminum powder with stronger reactivity and higher combustion efficiency.At present,most researches focus on the single-component compounding of aluminum powder,which shows limited improvement in its reactivity and combustion efficiency.In the dual-functionalized aluminum based ternary fuel（Al/PFPE/Cu₂O）,perfluoropolyether（PFPE）can effectively decompose the Al₂O₃ shell layer on the surface of aluminum powder.Cu₂O acts as an oxidant for thermite reaction,on the other hand,it can effectively catalyze the thermal decomposition of ammonium perchlorate（AP）as a catalyst.The synergism of PFPE and Cu₂O can improve the combustion performance of Al,which could solve the above problems.This thesis investigates effects of morphology and structure of Cu₂O,the content of Cu₂O and PFPE,and the size of aluminum powder on the combustion performance of aluminum powder by X-ray diffraction（XRD）,scanning electron microscope（SEM）,transmission electron microscope（TEM）,energy dispersive X-ray spectroscopy（EDS）,Fourier transform infrared spectroscopy（FTIR）,simultaneous differential scanning calorimeter and thermogravimetric analysis（SDT/DSC-TGA）and high-speed video camera.Results show that cubic Cu₂O possesses better promotion on Al exothermic reaction due to its higher surface energy among cubic,octahedral,and dodecahedral Cu₂O.When the equivalent ratio is larger than 1,the mass ratio increase of Cu₂O has good effects on the reactivity and combustion efficiency of the Al/PFPE/Cu₂O system.In addition,the size of aluminum powder has large influence on its combustion efficiency.The reactivity and combustion efficiency of nano-aluminum powder and its composite materials are stronger than that of micron aluminum powder.The dual-functionalized aluminum based ternary fuel exhibits excellent combustion performance when employing nano-aluminum powder and cubic Cu₂O,and 3/5/2 for the mass ratio of Al/PFPE/Cu₂O.The self-propagating combustion time of Al/PFPE/Cu₂O is shortened to 225 ms comparing with pure nano-aluminum（3.92 s）in that condition.Compared with ordinary aluminum powder,employing dual-functionalized aluminum based composite fuel in HTPB solid propellant shows that the burning rate is significantly improved in all pressures.The m-Al/5PFPE/2Cu₂O shows the best comprehensive performance as the burning rate is increased by 16%at 6 MPa,and the tensile strength is increased by 9%at 70℃.The excellent exothermic and mechanical properties of the composite fuel provide a feasible solution for improving the combustion efficiency of solid propellants.