Synthesis And Combustion Properties Of Boron-based Energetic Composites

Due to its high energy density and high calorific value,boron has become one of the high-energy fuels for ramjet engines,and shows great potential as a candidate for high-performance propellants.However,due to the characteristics of boron,such as easy oxidation,difficult ignition,long combustion duration and easy attachment of combustion products to the surface of boron particles which is easily inhibiting their full combustion.Therefore,how to overcome the shortcomings of boron-based fuels and improve their combustion efficiency has become the focus of exploring new high-performance boron-based energetic materials.The current research results show that metal,metal oxide,metal fluoride,fluorine-containing polymer and other additives can effectively improve the combustion performance of boron.Therefore,based on the current research status,this paper studies three composite fuels of boron-small molecular organic matter,boron-metal/carbon-naphthalene and boron-metal/carbon-naphthalene-aluminum,respectively.The following conclusions are obtained by studying their structure and combustion performance:（1）Three different boron small molecular organic compound fuels were prepared by recrystallization method.Combustion heat values of composite fuels with different boron small molecular organic mass ratios were tested under oxygen atmosphere.Among them,B-Nap₂₀,B-DMG₁₀,and B-Mel₂₀ had higher combustion heat values,which significantly improved the combustion heat values of pure boron materials under the same conditions.The thermogravimetric analysis tests of the above three materials were conducted under simulated air atmosphere.The test results showed that small molecular organic compounds can cause boron to enter the intense combustion stage earlier at lower temperatures.The laser ignition test showed that the addition of small molecular organic compounds caused a micro explosion phenomenon,and the material burned violently.The test results of combustion condensation products showed that the three kinds of boron small molecular organic compound fuels still had incomplete combustion phenomena.（2）Firstly,three metal/carbon materials were prepared by pyrolysis in argon atmosphere.After boron and metal/carbon materials were mixed by grinding and mixing method,naphthalene and boron metal/carbon materials were uniformly mixed by recrystallization method to prepare boron metal/carbon naphthalene composite fuel.The combustion heat values of composite fuels with different boron metal mass ratios were tested,among which Ni₃B₁₀₀-Nap,Cu₁B₁₀₀-Nap,and Fe₁B₁₀₀-Nap had the highest combustion heat values.Thermogravimetric analysis tests were conducted on the above three materials in a simulated air atmosphere.The test results showed that after the introduction of metal/carbon materials,the new composite fuel compared to B-Nap₂₀,while ensuring that the combustion heat value did not significantly change,also reduced the reaction temperature at which the material reached the most intense combustion,and improved the heat release efficiency of the material.The laser ignition test results observed that the combustion dimension of the material increased after the addition of metal/carbon,The material burns violently,and no obvious characteristic peaks of metal oxides are observed in the combustion condensation products.This may be due to a low metal content or the reaction of metal oxides with other substances at high temperatures.（3）Boron metal/carbon aluminum materials were prepared by grinding and mixing method,and then naphthalene and boron metal/carbon aluminum materials were uniformly mixed by recrystallization method to prepare boron metal/carbon naphthalene aluminum composite fuel.The combustion heat values of composite fuels with the same mass ratio of boron metal were tested,among which Ni₁B₁₀₀-Nap-Al₅,Cu₁B₁₀₀-Nap-Al₅,and Fe₁B₁₀₀-Nap-Al₅ materials had the highest combustion heat values.Thermogravimetric analysis tests were conducted on the above three materials in a simulated air atmosphere.The test results showed that after the introduction of aluminum,the combustion heat value of the composite fuel decreased.The laser ignition test results observed that the combustion duration of the fuel after the addition of aluminum was shortened.The characteristic peaks of aluminum boron alloy and borate were observed in the combustion condensation products,which may be the reason for the reduced combustion performance of the fuel after the addition of aluminum.