Nanosilicon/NC/CL-20 Microfluidic Microspheres and Their Thermolysis and Combustion Performance

To prepare silica-based composite energetic materials with regular shape, good dispersion, and uniform particle size and thus improve their combustion performance and safety and better apply them in solid propellants, in this study, nSi (nanosilica powder)/NC/CL-20 composite microspheres were prepared by fluid-focused microchanneling with nitrocellulose (NC) as a binder and nSi nanopowder and CL-20 as raw materials via droplet microfluidics. Orthogonal experiments were conducted to determine the optimal process parameters for preparation, ultimately resulting in the successful synthesis of composite microspheres with uniform particle size and good sphericity. Additionally, this study characterized the thermal decomposition properties and combustion performance of three types of composite microspheres (nSi/NC/CL-20, µSi (micron-sized silicon powder)/NC/CL-20, and NC/CL-20). The results showed that the activation energy of nSi/NC/CL-20 reached 530.95 kJ/mol, higher than that of µSi/CL-20/NC (211.19 kJ/mol) and CL-20/NC (210.50 kJ/mol); its 5-second burst point temperature was the highest, reaching 590.33 °C. In terms of combustion performance, nSi/NC/CL-20 exhibited significantly superior maximum pressure (1.22 MPa) and pressure rise rate (1.6 MPa/s) compared to the other two samples. These results clearly demonstrate that the addition of nanosilica powder can effectively improve the thermal stability and combustion performance of composite microspheres.