Application Of Novel Energetic Quaternary Ammonium Salt Burning-rate Inhibitor

The cruise motors of multi-stage missiles demand propellant with low burning rate and high specific impulse.At present,ammonium oxalate(AO)and carbonate which belong to the inert burning rate inhibitors are commonly used to reduce the burning rate of propellant.The inert burning rate inhibitors get the disadvantage of high usage amount and low energy.So they reduce the burning rate of propellant,but also reduce the energy performance of propellant simultaneously.Quaternary ammonium salt which belongs to the inert burning rate inhibitor get the advantage of low usage amount so it can reduce the decrease range of the energy.Combined the high nitrogen energetic groups with quaternary ammonium salt,a new type of energetic quater nary ammonium salt can be formed.It can reduce the burning rate of AP/Al/HTPB propellant while further reduce the decrease range of the energy performance.In this paper,a new type of energetic quaternary ammonium salt burning rate inhibitor was designed.The relationship between the performances and the structures of the energetic quaternary ammonium salts was analyzed.The effect regularity of the energetic quaternary ammonium salt burning rate inhibitors to the explosion heat,burning rate and burning rate exponent of the AP/Al/HTPB propellant was investigated.The best energetic quaternary ammonium salt burning rate inhibitor was screened out.The efficient burning rate inhibition mechanism was explored.Serial energetic quaternary ammonium salt burning rate inhibitors were designed.The molecule structure characteristics of these compounds are: the tetrazole is introduced as energetic group,the substituents are alkyls which link to the positive nitrogen atoms of the tetrazole and the quaternary ammonium salt,and the anions are selected from halogen elements such as Cl or Br.Based on the molecule calculation and pH test,the relationship between the structures of the energetic quaternary ammonium salts and their performances was analyzed.The test results show that,all of the energetic quaternary ammonium salt burning rate inhibitors reduce the explosion heat of the AP/Al/HTPB propellants,the decrease range of EQAS2-4/10-1 is lowest.EQAS4-5 in the energetic quaternary ammonium salts group?(the same 5 alkyls),EQAS2-4/10-1 and EQAS2-4/12-1 in group ?(4 short alkyls and 1 long alkyl)reduce the burning rate of AP/Al/HTPB propellant more than 20%.They show good effect of burning rate inhibition.EQAS2-4/10-1 has been screened out as the efficient energetic quaternary ammonium salt burning rate inhibitor.When the additive amount of EQAS2-4/10-1 is 0.5%wt,the AP/Al/HTPB propellant achieves the lowest decrease range of explosion heat,the highest decrease range of burning rate and burning rate exponent.IR and SEM-EDS test results show that,hydrogen bonds can be formed between the quaternary ammonium salts and the surfaces of AP particles,and the polar adsorption arises.This is the main reason of efficient burning rate inhibition for energetic quaternary ammonium salts.In the energetic quaternary ammonium salts group?,the less of the C atom number in alkyls,the stronger of the alkaline,and the hydrogen bonds can be formed more easily.In the energetic quaternary ammonium salts group ?,the energetic quaternary ammonium salts with more C atom number in alkyls show higher ability to form hydrogen bonds with AP.DSC-TG results show that,exothermic peaks are exhibited in the thermal decomposition process of the energetic quaternary ammonium salts.This is the high energy characteristic of the energetic quaternary ammonium salts.The main reasons of the burning rate inhibition are the effects of the energetic quaternary ammonium salts to the AP low temperature decomposition and AP high temperature decomposition in AP/energetic quaternary ammonium salts systems.