Crystal phase control and ignition properties of HNS/CL-20 composite microspheres prepared by microfluidics combined with emulsification techniques

Improved controllability and energy density of ignition agents are of great significance for the development of energetic composite materials. In this study, droplet microfluidics and emulsification techniques were combined to prepare HNS/CL-20 composite microspheres with polyglycidyl azide polymer (GAP) as the binder. The influence of binder content on the morphology of microspheres was investigated, and the microspheres were characterized and tested for particle size, crystal structure, thermal decomposition, dispersibility, mechanical sensitivity, combustion behavior and detonation performance. The results showed that microspheres prepared with a binder content of 3% had higher sphericity and particle size uniformity. The microspheres retained the crystal structure of both HNS and CL-20 (ε-type). Compared with raw HNS, the microspheres had higher apparent activation energy, better safety performance, and good dispersibility. The ignition experiments and detonation performance tests show that HNS/CL-20 composite microspheres have excellent ignition performance, obvious combustion flame, and significant energy release effects, which are expected to achieve high energy and high-speed response of the igniter, thus improving the ignition reliability in special environments or systems.