The performance of composite energetic materials depends not only on their chemical composition but also on their microscopic architecture. Conventional preparation methods often suffer from poor structural uniformity and limited control over interfacial organization, making it difficult to simultaneously optimize combustion stability and energy output.
In a new study published in Energetic Materials Frontiers , researchers from China proposed a controllable assembly strategy based on micro-scale multiphase flow regulation to fabricate BaCrO₄@B core-shell energetic microspheres with precisely engineered spatial structures, offering a scalable manufacturing strategy for precisely constructing core-shell energetic microspheres using micro-scale multiphase flow regulation.
"Precise structural modulation is critical for the functionalization of energetic materials," explains corresponding author Meng Wang. "This core-shell decoupling and sequential refinement strategy provides an ideal platform for elucidating structure-performance relationships and customizing functional energetic materials."
The researchers first generated highly spherical BaCrO₄ core microspheres through continuous droplet ejection, achieving a sphericity exceeding 95%. Subsequently, a pneumatic atomization process was employed to uniformly deposit a boron/nitrocellulose (B/NC) shell onto the microsphere surface, producing well-defined core-shell energetic particles.
“Systematic characterization confirmed uniform elemental distribution, preserved crystal structure, and continuous shell coverage,” says Wang. “By combining computational fluid dynamics with experimental optimization, we were able to establish stable particle dispersion conditions and achieved quantitative regulation of shell thickness through spray time and binder concentration.”
Notably, a binder-bridging mechanism was found to overcome the self-limiting behavior typically encountered during surface coating, enabling precise shell thickness control over a boron content range of 12.5–19.2 wt%.
Further, thermal analysis revealed that the core-shell architecture fundamentally altered the reaction pathway. “Unlike conventionally mixed powders, BaCrO₄@B microspheres exhibited two distinct exothermic stages corresponding to sequential interfacial reactions, producing a total heat release of 2480.76 J g⁻¹,”Wang shares. “The staged reaction indicates that the spatial separation of oxidizer and fuel actively regulates energy release rather than allowing uncontrolled reactions.”
Laser ignition experiments further demonstrated that combustion behavior strongly depends on microstructure. While blended microspheres burned rapidly with high flame intensity, the core-shell microspheres exhibited a gentler and more stable combustion mode governed by interface-controlled reactions. “The controlled combustion process reduces stochastic fluctuations while maintaining effective energy output, illustrating how structural engineering can tailor energetic performance without altering material composition,” adds Wang.
Taken together, the team's findings provided a methodological foundation for the customized design of composite energetic materials and highlight the growing role of structural engineering in optimizing the safety and performance of advanced pyrotechnic and energetic systems.
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Contact the author:
School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China. E-mail addresses: joey@njust.edu.cn (M. Wang)
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Energetic Materials Frontiers
Controllable Assembly of BaCrO4@B Core Shell Energetic Microspheres Based on Micro-scale Multiphase Flow: Precise Structural Design and Energy Modulation.
The authors declare no competing financial interest.