Integrated Continuous Preparation And Properties Of Energetic Composite Microspheres By Microfluidic Technology

While ensuring the high energy properties of energetic materials,developing the intrinsic safety of their application processes and the technological safety of their preparation processes has important theoretical and practical significance.This paper proposes a new strategy for the continuous preparation of energetic composite microspheres using microfluidic technology from synthesis to spheroidized coating.Based on a safe and continuous preparation process,spheroidized coated explosives are synthesized,controlled,and prepared at a micro scale.Using 3,3’-diamino-4,4’-oxofurazan（DAAF）and hexanitrohexaazaisowurtzitane/2,4,6-trinitrotoluene（CL-20/TNT）cocrystal explosives as the main research subjects,an integrated microfluidic preparation platform was designed and built to achieve the integrated and continuous preparation of explosives from synthesis to spheroidization coating.Based on the research subject,the feasibility and applicability of uniform spheroidization of each component during the coating process under the integrated continuous preparation of microfluidic technology were verified when the energetic materials were solid,liquid,solid（low density）-liquid,and solid（high density）-liquid phases.Through different formulation designs,different energetic microsphere samples were prepared continuously and integrally,and their properties were characterized and analyzed.The main contents are as follows:（1）Integrated continuous preparation of DAAF based energetic microspheres using microfluidic technology.Taking DAAF as the main research subject,a microfluidic technology platform for integrating DAAF from synthesis to spheroidization coating was designed and built.The optimal process conditions for synthesizing DAAF in the micromixing stage were obtained using orthogonal test methods.The DAAF was continuously coated into three sizes of microspheres using F₂₆₀₄,NC,and NC/GAP adhesives,the designed microfluidic platform can effectively regulate the particle size of DAAF microspheres under different binder formulations.Through characterization and analysis of the sample,the results show that:The sample microspheres prepared from synthesis to spheroidization have regular spherical morphology,good monodispersity,and uniform particle size distribution;The integrated continuous preparation process does not change the crystal structure of DAAF;The mechanical sensitivity of the prepared microspheres is lower than that of DAAF,and the safety performance is improved.At the same time,the feasibility of uniform spheroidization of each component during the coating process under the integrated continuous preparation of microfluidic technology was verified when the energetic material was solid.（2）Integrated continuous preparation of CL-20/TNT cocrystal based energetic microspheres using microfluidic technology.Taking CL-20/TNT cocrystal as the main research object,a microfluidic integrated continuous preparation platform for CL-20/TNT cocrystal assembly and spherical coating was designed and built.Using this platform,pure CL-20/TNT cocrystal was prepared,and NC and NC/F₂₆₀₄ adhesives were used to spheroidize and coat the CL-20/TNT cocrystal during its formation.The cocrystal assembly and coating process of the sample were studied.Through characterization and analysis of the sample,the results show that:The cultured pure CL-20/TNT cocrystal has a single crystal structure;By analyzing and comparing the crystal structure and chemical structure of pure CL-20/TNT cocrystal,it was proved that CL-20/TNT cocrystal was successfully formed in microspheres coated with NC and NC/F₂₆₀₄ adhesive;The prepared microspheres show regular spherical shape,high degree of coating,good dispersion,and better fluidity than the raw materials;The prepared microspheres have enhanced thermal stability,reduced mechanical sensitivity,improved safety performance,and a more stable and excellent self-sustaining combustion ability than raw materials.At the same time,the feasibility of uniform spheroidization of each component during the coating process under the integrated continuous preparation of microfluidic technology was verified when the energetic material was in the liquid phase.（3）Integrated continuous preparation of CL-20/TNT cocrystal/DAAF composite energetic microspheres using microfluidic technology.Taking DAAF and CL-20/TNT cocrystal as the main research subjects,using the designed and built microfluidic technology platform,NC/GAP adhesive was used to coat mixed systems of different solid phase DAAF particle content（10%,25%,40%）and liquid phase CL-20,TNT.Through the characterization analysis of the samples,the results show that:The successful formation of CL-20/TNT cocrystal in the prepared microspheres was proved by comparing with the crystal structure and chemical structure of pure CL-20/TNT cocrystal;The samples showed regular spherical,uniform particle size distribution,high degree of monodispersity,and the angle of repose increased compared with CL-20/TNT cocrystal microspheres;The addition of DAAF can inhibit the flame generation of CL-20/TNT cocrystal,prevent its deflagration to detonation transition（DDT）process,effectively reduce its sensitivity,and improve its safety.At the same time,the feasibility of uniform balling of each component when the energetic material was solid phase（low density）-liquid phase during the coating process under the integrated continuous preparation of microfluidic technology was verified.（4）Integrated continuous preparation of CL-20/TNT cocrystal-based aluminized explosive by microfluidic technology.With CL-20/TNT cocrystal and Cu/Al composite particles as the research subjects,the integrated safe preparation of CL-20/TNT cocrystal-based aluminized explosives was carried out using the designed microfluidic technology platform.Through the characterization analysis of the samples,the results show that:Compared with pure CL-20/TNT cocrystal,the formation of CL-20/TNT cocrystal in microspheres was proved.The prepared aluminized explosive microspheres have a high level of sphericity and a narrow range of particle size distribution.The element mapping diagram shows that the components are evenly distributed in the microspheres,and the metal particles have no obvious aggregation;The addition of Cu/Al composite particles has a catalytic effect on the thermal decomposition of CL-20/TNT cocrystal.Compared with CL-20/TNT cocrystal microspheres,the combustion performance of microsphere samples was significantly improved,the combustion reaction was more intense,the mechanical sensitivity was reduced,and the safety level was further improved.At the same time,the feasibility of uniform balling of each component when the energetic material was solid phase（high density）-liquid phase during the coating process under the integrated continuous preparation of microfluidic technology was verified.