Effects of binder systems on the 3D printability and combustion performance of Al/AP energetic composites

In order to investigate the influence of different binder systems on the adaptability to 3D printing processes and combustion performance, this study selected hydroxyl‑terminated polybutadiene (HTPB) and phenolic resin (PF) as two types of binders to prepare Al/AP-based energetic slurries, and conducted a systematic comparative study. The shear-thinning behavior and thixotropy of the two slurries were characterized through rheological tests. Based on these results, key process parameters such as printing pressure and extrusion speed were optimized, enabling the successful rapid prototyping of strip structures and multi-layer cylindrical structures. Using scanning electron microscopy and micro-computed tomography, the influence of different binders on the microstructure and morphology of the printed samples was analyzed. The porosity of the Al/AP/HTPB sample was measured to be 5.87%, while that of the Al/AP/PF sample was 1.68%. Combustion performance tests revealed differences in the ignition and combustion characteristics between the two types of 3D-printed samples. The Al/AP/HTPB sample exhibited an ignition delay time of 74 ms and a burning rate of 21.69 mm/s ± 1.42 mm/s, whereas the Al/AP/PF sample showed an ignition delay time of 116 ms and a burning rate of 30.22 mm/s ± 1.86 mm/s.