Preparation Of Nano-FOX-7 By Solvent-non-solvent Method And Catalytic Effect Of Nano-CoO On FOX-7

1,1-Diamino-2,2-dinitroethylene?C₂H₄N₄O₄,FOX-7?is a kind of insensitive and high energy explosive that was synthesized by the Swedish National Defense Research Institute in the early 21st century.FOX-7 has exerted great interests among military research staffs due to its excellent comprehensive performances of high energy,low sensitivity and high detonation.It is considered to be a potential substitute for hexogen?RDX?and octogen?HMX?.It has broad application and development space in the field of high energy and insensitive explosives.So FOX-7 is selected as a research object.General nano-FOX-7 and one-step exothermic nano-FOX-7 are prepared successively using a mild and general solvent-non-solvent method.Moreover,the thermal decomposition catalytic effect of nano-CoO on FOX-7 was studied.The main contents of this paper are as follows:?1?Using DMAC,NMP and the mixture of the two materials as the solvents,nano-FOX-7was prepared by the solvent-non-solvent method.The morphologies,phases,structures and thermal properties of the prepared nano-FOX-7 were characterized using FE-SEM,XRD,FT-IR,DSC and TG.Meanwhile,the sensitivities of the prepared samples were also analyzed.In addition,on the basis of that,the effects of solvents and surfactants on the properties of nano-FOX-7 were also investigated.The results show that the average grain sizes of the prepared nano-FOX-7 are less than 30 nm,while its partial particle sizes are less than 100nm.It is conductive to reduce its grain and particle sizes,enhance the uniformity of the particle size distributions and improve its dispersion effects when adding surfactants into the FOX-7 solution in the process of preparation.Compared with the raw FOX-7,the low decomposition temperature,the energy release efficiency and the decomposition enthalpy of the prepared nano-FOX-7 increase,while the impact and friction sensitivities significantly reduce.When using the mixed solvents and adding the surfactants of OP-10 and Tween 20into solutions,the thermal decomposition enthalpy increase by 4.97%and 4.65%respectively.However,the friction sensitivities decrease by 66.7%and 50.0%respectively.?2?The one-step exothermic nano-FOX-7 were prepared by solvent-non-solvent method using Tween 80 as an additive,DMAC,NMP and the mixture system of the two materials as solvents.The morphologies,phases,structures and thermal properties of the prepared simples were characterized using FE-SEM?XRD?FT-IR?DSC-TG.Besides,the thermal decomposition kinetics of one-step exothermic nano-FOX-7 were studied.The results show that the average grain sizes of the prepared nano-FOX-7 are less than 30 nm,and its partial particle sizes are less than 100 nm.Compared with the two-steps decomposition exothermic process from the raw FOX-7,the prepared nano-FOX-7 has one-step exothermic property.As a result,there are just one exothermic peak in its DSC curves and only one weight loss process in its TG curves.The thermal stability,heat release and energy release efficiency of the prepared samples were significantly improved.During the preparation process,the surfactant Tween 80 greatly affects its one-step exothermic performance due to the formation of hydrogen bond between Tween 80 and FOX-7.?3?The CoO/FOX-7 nanocomposites were prepared by ultrasonic dispersion process using n-hexane as a dispersion solvent.The results from thermal analysis show the addition of nano-CoO reduces the decomposition temperatures of FOX-7,consequently promote its thermal decomposition.When the addition amount of nano-CoO was 3wt%,initial thermal decomposition temperature decreases by 7.47?;When the addition amount of nano-CoO was 4wt%,the second thermal decomposition temperature decreases by 7.14?.