Study On Crystal Types Control And Coating Formula Design Of Ultrafine CL– 20

Hexanitrohexaazaisowurtzitane(CL-20) is a kind of cage high explosive,it has high density, large power and high detonation velocity,is one of the most widely used explosives at home and abroad.But the CL-20 has four types of crystal at room temperature,crystal transformation is very easy to occur in solution recrystallization,and itself has very high mechanical sensitivity,these limit the develop of CL-20 in military application,so controlling the crystal transformation mechanism and lowing the sensitivity of CL-20 has very important significance.In this paper, the crystal transformation mechanism of CL-20 were studied,the micron level CL-20 was obtained by recrystallization and four kinds of binder/plasticizer formula were choosed to cladd CL-20.The main work is shown below:By experiment research,in the process of refining the solvent/non solvent system,different temperature, different solution drops to accelerate the rate of CL-20 was greatly influenced by the crystal shape, small dipole moment of the solvent, temperature of below65 ℃, accelerating at a rate of 1 ml/min were most appropriate.In the process of coating,the temperature had a greater influence on the crystal type of CL-20, 60 ℃ was the most appropriate.By MS software, the ε-CL-20, adhesive molecules and PBX explosive mode were builded.After caculating the binding energy of the PBX explosive,the five kinds of binder and CL-20 explosive had good compatibility,the sorting order of binding energy was Polyacrylate(AR-12)>Estane5703>F2311>F2602>EPDM,the greater the stability of the binding energy was, the greater the said preparation of PBX explosive would be.According to the binding energy, choosing polyacrylate rubber, Estane5703 as optimal adhesives.Micron level CL-20 was prepared by ultrasonic spray refining device,and the refined CL-20 has been characterized and tested.The results showed that,the size of refined CL-20 was 2 μm,the surface of the crystal was smooth and has spherical shape,the crystal of refinedCL-20 was consistent with the raw material of CL-20,and had wider diffraction peak.Compared with raw materials of CL-20,the impact sensitivity of refined CL-20 dropped significantly, the characteristic height rised from 17.98 cm to 31.95 cm.Compared with raw materials of CL-20,the refined CL-20 had better thermal stability,the activation energy increased 9.8 KJ/mol, had better thermal stability.CL-20 PBX explosive was successfully achieved by water suspension device, using Estane and polyacrylate(AR-12)as binder, with calcium stearate, titanium dioxide,polytetrafluoroethylene as plasticizer.The PBX explosives had been characterized and tested,the results showed that,after adding plasticizer, the crystal form of CL-20 PBX explosives did not changed, still were the epsilon type.The impact sensitivity and DCS thermal decomposition characteristics of CL-20 PBX explosives were analyzed, coMPared before adding plasticizer, the impact sensitivity decreased obviously, thermal decomposition performance improved obviously. The explosive velocity of CL-20/polyacrylate/polytef was 8981 m/s.