The Mechanism And Suppression Techniques Of Agglomeration And Growth Of Ultrafine Explosive

Many excellent properties of ultrafine explosives have been found. Due to the peculiaractivity of ultrafine explosives, it is prone to agglomeration and growth. And this will resultin the excellent properties of ultrafine explosives can’t be fully realized. Therefore, it hasimportant significance for us to study the mechanism and suppression techniques ofagglomeration and growth of ultrafine explosive.This paper summarized the research situation at home and abroad on refinementtechnology of explosive. And also summarized the overseas and domestic research situationon the mechanism and suppression techniques of agglomeration and growth of ultrafineexplosive. A number of theories and concepts involved in the refinement technology of theexplosive and the mechanism of agglomeration and growth of ultrafine explosive were alsoanalyzed.The problem of agglomeration and growth exist in many ultrafine explosives. Due to thedifference in its structure, properties and preparation methods, the problem of agglomerationand growth of different explosives have different forms. In the refining process, the problemof agglomeration and growth of HMX and HNIW is particularly prominent. Therefore, thestudy of the mechanism and suppression techniques of agglomeration and growth of HMXand HNIW should be combined with the characteristics of agglomeration and growth ofthemselves.The HMX was prepared by spray-fine method. And the prominent problem onpost-processing was the growth of HMX crystal, which occurs mainly in the drying stage. Inthis paper, the reasons of the growth of the HMX crystal were analyzed combined with theparticularity of HMX crystals. In the process of post-processing, liquid membrane is the rootcause of the growth of HMX. Furthermore, surface energy, capillary force and so on are also the cause of the growth of HMX. Both theoretical analysis and experimental studies indicatethat freeze-drying method and the addition of suitable dispersant have inhibiting effect onHMX crystal growth. The freeze-dried technics was optimized. The mean diameter of theHMX, which prepared by the optimized freeze-dried technics, was between849.3~905.3nm.And the dispersity of the HMX was very good. When the HMX filter cake were soaked by0.3%polyvinylpyrrolidone solution, the d50of the prepared HMX was1.0806μm and the dispersityof it was good.The HNIW was prepared by recrystalization with solvent-nonsolvent method. Andthe prominent problem on preparation process were agglomeration, growth and polymorphictransformation of HNIW crystal. In the study of the problem of agglomeration and growth ofthe HNIW crystal, polymorphs issues should also be considered. The mechanism of action ofdispersant were analyzed by nucleation rate, interfacial diffusion theory and the degree ofsupersaturation. The above reaction mechanism explains that dispersant PVP has the effect ofinhibiting HNIW crystal agglomeration and growth, which is consistent with theexperimental results of this paper. When the PVP was added to the ethyl acetate/cyclohexanesystem and the ethyl acetate/n-heptane system, respectively, the d50of the prepared ε-HNIWwere0.9895μm and1.3135μm. And in comparison with the raw materials HNIW, the impactsensitivity significantly reduced.