Preparation And Performance Research Of DAAF-based Insensitive PBX

3,3'-Diamino-4,4'-Azofuroxan(DAAF)is one of the representatives of furoxan energetic compounds.DAAF has the characteristics of high energy,low sensitivity,good thermal stability and environmental protection during the synthesis process.Based on the standard PBXN-7 booster(the formula is TATB/RDX/Vition A=60/35/5),two DAAF-based PBX formulas are designed,the DAAF microspheres and DAAF/TKX-50 microspheres with good morphology were prepared by self-assembly recrystallization technology.DAAF/F₂₆₀₂complex and DAAF/TKX-50/F₂₆₀₂complex were prepared by solution-water suspension method,and finally tested and characterized.The main content has the following aspects:1.Binder screening:The molecular dynamics simulation of PBX composed of DAAF and three binders F₂₃₁₁,F₂₃₁₄and F₂₆₀₂was carried out by using Forcite module of Materials studio software,and the bonding energy and mechanical properties between explosives and binders were calculated.The results showed that the binding energies of the three binders and DAAF were:F₂₆₀₂>F₂₃₁₁>F₂₃₁₄.The mechanical properties of PBX after adding three kinds of binders were improved compared with DAAF,and other properties such as oil resistance,acid resistance and thermal oxidation resistance of F₂₆₀₂were superior to those of F₂₃₁₁and F₂₃₁₄,so F₂₆₀₂was the preferred binder for DAAF-based PBX.2.Preparation of DAAF microspheres:Using dimethyl sulfoxide as solvent and water as non-solvent,spherical DAAF particles were prepared by confined self-assembly recrystallization technology,and the solvent/non-solvent ratio,temperature,stirring speed,drop The effect of acceleration and PVP molecular weight on the morphology of the prepared DAAF particles.The results showed that when the temperature was 16?,the solvent-to-solvent ratio was 1:40,the stirring speed was 150 r·min^-1,and the dropping rate was 2.5 m L·min^-1,the prepared DAAF particles were spherical and the PVP of different molecular weights had an effect on DAAF morphology.The impact was not obvious.The samples were tested and characterized by scanning electron microscope,X-ray powder diffractometer and differential scanning calorimeter.The results showed that the crystal form of the refined DAAF microspheres did not change,and DAAF(K90)and DAAF(K17)were fine.Compared with the raw materials,the average apparent activation energy of the modified DAAF was reduced by 23 k J·mol^-1and 38.58 k J·mol^-1,respectively,and the thermal stability was reduced.The mechanical sensitivity test showed that the impact sensitivity height of DAAF raw material and DAAF microspheres were both greater than 100 cm,and the friction sensitivity was 0%,indicating that DAAF has better safety performance.3.Formula design:According to the standard PBXN-7 booster explosive speed,two DAAF-based PBX formulas were designed and determined;DAAF/F₂₆₀₂(95/5)and DAAF/TKX-50/F₂₆₀₂(60/35/5),The theoretical detonation velocities are 8167 m·s^-1and 8544m·s^-1respectively,which are both higher than the theoretical detonation velocity of PBXN-7of 8160 m·s^-1.4.DAAF/F₂₆₀₂(95/5)PBX preparation:The sub-micron-DAAF(K90)/F₂₆₀₂and sub-micron-DAAF(K17)/F₂₆₀₂were prepared by the solution water suspension method,and it was found that when coated with DAAF(K90),the coating effect was not good.Therefore,micron-DAAF was used as a control and compared with sub-micron-DAAF(K17)/F₂₆₀₂.The effect of particle size on the coating effect was discussed,and performance tests were performed on sub-micron-DAAF(K17)/F₂₆₀₂and micron-DAAF/F₂₆₀₂.The results showed that the DAAF crystal form would not change after coating;the average apparent activation energy of sub-micron-DAAF(K17)/F₂₆₀₂and micron-DAAF/F₂₆₀₂were increased by 9.23k J·mol^-1and 3.59 k J·mol^-1,respectively.The use of binders can improve its thermal stability.The impact sensitivity characteristic drop height was greater than 100 cm,and the friction sensitivity was both 0%;the response degree of the fast and slow cook-off was both the burning level,indicating that the safety performance is better.5.DAAF/TKX-50/F₂₆₀₂(60/35/5)PBX preparation:the DAAF/TKX-50 mixed explosive was refined by self-assembly recrystallization technology,and the refined DAAF/TKX-50was coated by the water suspension method,the obtained samples were tested and characterized by scanning electron microscope,X-ray powder diffractometer and differential scanning calorimeter.The results showed that the DAAF/TKX-50 was in the shape of flower clusters after thinning,and the samples after coating were similar.Spherical,smooth surface,and no change in crystal form.Compared with TKX-50,the thermal decomposition peak temperature of DAAF/TKX-50 after mixing is increased by about 15-20?,and the average apparent activation of DAAF/TKX-50/F₂₆₀₂Compared with DAAF/TKX-50,it can increase by 29.24 k J·mol^-1,indicating that the thermal stability was significantly improved.The impact sensitivity test results showed that the impact sensitivity characteristic drop height of DAAF/TKX-50 was 44 cm higher than that of TKX-50,and the characteristic drop height of DAAF/TKX-50/F₂₆₀₂was greater than 100 cm,and the safety was significantly improved.