Effect Of Organic Fluorine Or Boron Containing Additives On Combustion Performance Of Aluminized Propellants

Aluminum is high-energy fuel in composite solid propellant,but agglomeration of aluminum particles during combustion causes incomplete combustion of aluminum and two-phase flow energy loss.In addition,borohydride compound has a high combustion heat value and the ionization potential of releasing hydrogen is very low,it can accelerate the decomposition of nitramine,so it's an effective way to regard borohydride compound as solid propellant burning rate catalyst to obtain high burning rate.In this paper,organic fluorine-containing additives were used in aluminized polyether propellants,three types of borohydride compounds were applied in aluminized HTPB propellants,and then we analyzed their combustion performance and condensed combustion products.First,the scanning electron microscope?SEM?,laser particle size analyzer and so on were applied to study the influence of organic fluorine-containing additives on propellants condensed combustion products,after organic fluorine-containing additives replaced 3%aluminum or 3%AP in PET/N-100 binder system,respectively.The results show that organic fluorine-containing additives contribute to reduce coarse agglomerate size after adding to aluminized polyether propellants,and the most significant reduction happened from organic fluorine-containing additive replaced AP rather than aluminum.This part explored the influence of organic fluorine-containing additives on aluminum agglomeration during combustion of the aluminized polyether propellants after it replaced1%-5%AP respectively.The results show that organic fluorine-containing additives contribute to reduce the size of burning aluminum particles.coarse agglomerate size is reduced obviously after adding 2%organic fluorine-containing additives,at 7MPa,the average diameter of condensed combustion products is decreased from 5.83?m to 3.06?m;XRD results show that?-Al₂O₃ and?-Al₂O₃ is nearly disappeared in condensed combustion products,there are mainly?-Al₂O₃ and?-Al₂O₃ as addition of organic fluorine-containing additives.However,the burning rate and explosion heat of the propellants are decreased a little due to the addition of organic fluorine-containing additives.On the one hand,K-₂B-₁₂H₁₂,C₁₄H₃₀N₈B₁₂H₁₂ and C₂H₁₈N₁₂B₁₂H₁₂ replaced 3%RDX respectively,on the other hand,K₂B₁₂H₁₂ replaced 1%-3%RDX respectively,and then we studied the influence of these borohydride compounds on combustion performance and condensed combustion products of the aluminized HTPB propellants.The results show that the burning rates are increased?3-9MPa?after adding these borohydride compounds,the order is C₂H₁₈N₁₂B₁₂H₁₂>K₂B₁₂H₁₂>C₁₄H₃₀N₈B₁₂H₁₂>reference,and the burning rate exponent changes little.