Research On The Crystallization Behavioral Of NTO

As a high-energy and low-sensitivity energic material,3-nitro-l,2,4-triazole-5-one（NTO）has been one of the hot applications of fire explosives at domestic and overseas in recent years.The morphology of the direct synthesis of NTO is poor and easy to aggregate.The crystals obtained from the research on NTO crystallization in the existing literature are mainly aggregated spherules.For better use in the military field,it is significant to research its crystal performance in depth.The solubility of NTO in water,ethanol and methanol of these pure solvents with Laser Dynamic Technology,was determined by laser dynamic method,and are correlated with the Apelblat and Van’t Hoff equation.The solubility of water in a mixed system composed of methanol was measured,and are correlated by the Apelblat,Yaws,（CNIBS）/R-K and Jouyban-Acree equation.The thermodynamic parameters-solid,liquid surface tension and surface entropy factors of the dissolution process of NTO in the above-mentioned solvent system are calculated.The results show that the solubility of NTO in each solvent increases with the increase of temperature and alcohol content.The cooling crystallization behavior of NTO in three pure solvents-water,ethanol,and methanol-was studied experimentally based on the design of the cooling rate,crystallization temperature,and stirring rate.The crystal morphology and bulk density were the main indicators,and a better pure solvent system for NTO crystallization was obtained.The cooling crystallization behavior of NTO under different mixing ratios was studied by using the preferred pure solvent-methanol and water to form a mixed solvent.Comparing the crystallization effects in those pure solvents and mixed solvents,a better system was selected to study the crystallization behavior of NTO under the action of different additives,and finally an optimized cooling crystallization process was obtained.The results show that the better solvent system for NTO crystallization is methanol/water=95:5.The crystallization is cooled in a mixed solvent system with methanol/water=95:5.The better cooling crystallization process is the crystallization temperature is 45℃,the cooling rate is 0.1℃·min^-1,the stirring rate is 400rpm,and the amount of triton addition is 0.2%.The bulk NTO crystals with an apparent density of0.80g·cm^-3 and a medium particle size(D₅₀)of 26.22μm were obtained.