With the aim of investigating the changing law of crystallization driving force of typical energetic compounds under micro-scale crystallization conditions, a thermodynamic parameter determination method based on optofluidics was proposed. Aimed at nitro, nitramine and nitrate explosives in energetic compounds, hexanitrostilbene (HNS), cyclotetramethylene tetranitramine (HMX) and pentaerythritol tetranitrate (PETN) were selected as representatives, the solubility of the three kinds of energetic compounds in their respective commonly used solvents (HNS: in DMF, DMSO, NMP; HMX: in DMF, DMSO, CYC; PETN: in DMF, DMSO, EAc) at different temperatures were determined. Furthermore, microfluidics and machine learning were combined, the solubility data of the explosives were processed using BP neural network. Moreover, the metastable zone widths of HNS, HMX and PETN in each solvent were determined using on-line Raman technique. Additionally, crystalline thermodynamic parameters such as solid-liquid interfacial tension, crystal surface entropy factor, enthalpy of dissolution and etc. were calculated for each system.

The regulation of energy release characteristics and safety of highly active metal fuels has attracted significant attention. In response to the limitations of using hydrofluoric acid (HF) to modify zirconium (Zr) powder in batch reactors, a microfluidic method coupling ultrasound and coaxial flow microreactors was proposed to achieve the control of the microstructure on the surface of Zr powder. The fluid flow and mixing characteristics in the microreactor were analyzed using on-line detection devices, leading to the determination of suitable fluid parameters. Through analysis of the reaction process between Zr and HF, a reaction model based on the HF concentration was established and subsequently verified through a microreaction system. The results indicate that the HF concentration greatly influences the morphology and composition of Zr powder, thereby determining the material and structural transformation of the Zr powder surface. The excellent thermal oxidation performance and electrostatic safety of HF-modified Zr powder were confirmed through thermal analysis and electrostatic discharge sensitivity tests. This study provides valuable insights for controlling the microstructure and properties of ultrafine Zr powder.

Improving the quality of mixing between multiple components is expected to enhance the macroscopic performance of the composite energetic materials. To address the limitations associated with intermittent manual techniques in multicomponent mixing, a novel strategy that integrates microfluidic with spray drying technology was proposed to achieve the safe and continuous fabrication of ultramixed energetic composites. B/KNO(3 )was utilized as a representative example to validate the applicability of this strategy. This strategy allows for the simultaneous refinement of raw materials and assembly of multicomponent microscale interfaces, enabling a "one-step" synthesis approach. A microscale assembly model for composite components was constructed and applied to describe the microscopic morphology of the composite particles under different conditions. The microscopic morphology of B/KNO(3 )was analyzed under different component concentrations, drying temperatures, and gas flow rates to validate the applicability of the model. Based on the TG-DSC results, a qualitative explanation was provided for the relationship between the microstructural configuration of the composite system and its macroscopic thermal performance when the B/KNO3 ratio is constant. In addition, laser ignition experiments were conducted to evaluate the combustion characteristics of the ultramixed B/KNO3. Encouragingly, the quality of interfacial composite materials plays a crucial role in influencing the macroscopic reactivity, as the ultramixed B/KNO3 exhibits consistent burning rates and high delay accuracy. The proposed micro continuous flow-spray strategy not only offers novel insights into modulating the macroscopic performance of composite energetic materials through enhanced interfacial blending but also provides valuable references for the continuous fabrication of other composite materials. Moreover, this strategy prioritizes intrinsic safety aspects and effectively addresses pertinent concerns associated with the handling and processing of energetic materials.

Polymorphic transformation is of paramount importance as it significantly influences the physical, chemical, and functional properties of materials, with profound implications in fields ranging from advanced materials engineering to high-energy material science. However, there is difficulty in understanding transformation mechanisms, achieving precise control over transformation processes, and addressing the stability of polymorphs. This work sets its sights on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), a typical polycrystalline explosive, and innovatively embarks on the development of a control strategy for polymorphic transformation from both mechanistic and experimental perspectives by microfluidics. We delve into the microscopic transformation mechanisms from the alpha-form to the beta-form and eventually to the epsilon-form, utilizing molecular dynamics simulations incorporating thermodynamic and kinetic principles. To control these transitions, a custom-engineered coaxial micromixer was developed, leading to the establishment of an advanced microfluidic system for polymorph control. The groundbreaking mechanism was validated by scrutinizing the influence of microfluidic conditions on the polymorphic transformation, facilitating a continuous and efficient transition from alpha-CL-20 to epsilon-CL-20-PBX. Notably, thermal decomposition tests provided further endorsement, confirming the superior storage safety and reliability of epsilon-CL-20-PBX. The findings offer an unprecedented understanding of the polymorphic transformation of explosive materials and open new avenues in the manipulation of polycrystalline materials.

The controlled construction of hybrid material structures can effectively regulate the physical, chemical, and functional properties of materials. This work explores the feasibility of coupling microdroplets technology and photopolymerization methods to achieve controllable construction of hybrid structures on the surface of ultrafine zirconium (Zr) powder, and investigates the effects of different hybrid structures on the surface mechanical properties, thermal oxidation performance, and electrostatic safety of Zr powder. The photopolymerization reaction process of PMMA on the surface of Zr powder was analyzed, revealing the principle of accelerated photopolymerization reactions within microdroplets, which was experimentally validated. Furthermore, by altering the polymerization reaction conditions and with the assistance of hydrofluoric acid (HF), a mechanism for controlling the hybrid structures on the surface of Zr powder was proposed. The results demonstrated that the collaborative effect of microdroplets and photopolymerization methods efficiently controlled the content and structural characteristics of the PMMA coating on the surface of Zr powder. The further introduction of HF was found to adjust the morphology of the surface hybrid structures and significantly improve the thermal oxidation performance and electrostatic safety of the Zr powder. These findings provided insights into the surface property regulation of active energetic materials and paved the way for the controlled preparation of inorganic-organic hybrid materials.

Restricted by the macroscopic spatial scale conditions in traditional preparation methods, the improvement of delay precision of the delay composition gradually arrives at the bottleneck. Therefore, a microdroplet-confined coupling polymer self-assembly theory based on microfluidics was proposed to prepare ultramixed self -assembled composite energetic material particulates in order to make a breakthrough in its delay precision. Taking boron (B)/barium chromate (BaCrO4) delay composition as the research object, nano-BaCrO4 particles were prepared and microdroplet templates were generated by using the micromixing and microdispersing re-action systems respectively. With the excellent mixing efficiency of the micromixing reaction system, the effect of reactant concentration and temperature on crystal morphology and particle size of BaCrO4 was investigated, and the spectral response of BaCrO4 particles was analyzed on-line by using an on-line UV-vis spectrophotometer. The results indicated that the reactant concentration exerted a great influence on crystal morphology and particle size of BaCrO4, and the characteristic absorption peak of BaCrO4 was red-shifted regularly with the decrease of crystal thickness at low reactant concentration. Microdroplet templates for self-assembly of B/BaCrO4 nano -composite particles were generated by using a microdispersing reaction system, and the self-assembled B/ BaCrO4 particulates were prepared. The particulates were characterized by thermal analysis and the delay precision was measured. The results exhibited that the composite energetic particulates with ultra-homogeneous mixing, excellent combustion performance and high delay precision were prepared. In summary, in this study, ultramixed self-assembled B/BaCrO4 particulates with high delay precision were prepared based on micro -fluidics, which can provide a novel technology and method for the preparation and mixing of other composites.

为连续化高安全性地实现锆粉的感度控制,构建了一个桌面式高通量微反应系统,并验证了利用该系统制备氢氟酸改性锆粉的可行性.通过调节流体流速比、流量及氢氟酸浓度,对改性锆粉的形貌与结构进行了研究.采用热分析法与静电火花感度测试对改性锆粉的热性能与安全性进行了分析.研究结果表明:桌面式高通量微反应系统可以实现形貌良好的锆粉改性制备,并达到每小时百克量级的处理量,改性后锆粉的表面主要由含氟氧化锆层与氢化锆层组成;氢氟酸改性锆粉的氧化速率更快,反应完全所需的时间更短,氧化增重较原料锆降低了

In order to achieve the safety of the preparation process of ultrafine zirconium （Zr） powder， a method for preparing core‑shell Zr powder by continuous flow at microscale was studied. A continuous microfluidic system consisting of microfluidic unit and spray‑drying unit was established to verify the feasibility. The system can realize the microscale mixing of components， the formation of core‑shell structure and the post‑processing of samples continuously. Using Zr powder and nitrocellulose （NC） as composite components， the structure regulation of Zr@NC was studied by controlling content of NC and adjusting dry gas pressure at the microscale. In addition， the activity and safety of Zr@NC were analyzed by thermal analysis and electrostatic spark sensitivity test. The results show that the Zr powder with uniform morphology and core‑shell structure can be prepared by the continuous microfluidic system. Thermal analysis results show that the oxidation weight gain of Zr@NC is only 1.04% lower than that of the raw Zr， and the energy release is faster. According to the electrostatic spark sensitivity test， it was found that the 50% ignition energy of Zr@NC is increased from 1.42 mJ to 197.82 mJ compared with the raw Zr， which means the electrostatic spark sensitivity is greatly reduced.