Comparative analysis of microstructure and combustion performance of flake and spherical aluminum powder and its application in chip self-destruction

The combustion performance of aluminum powder is closely related to its microstructural features, which significantly influence the engineering applicability of aluminum powder as metal fuel. In this study, six types of flake aluminum powders and six types of spherical aluminum powders were selected for a comparative investigation of their microstructural characteristics and combustion performance, employing techniques of Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), and oxygen bomb calorimetry. Additionally, research was conducted on the chip self-destruction technology based on aluminum powder. The results indicate that as the particle size of flake aluminum powder increases, the content of reactive aluminum also rises, leading to enhanced combustion heat value. Smaller-sized flake aluminum powders exhibited agglomeration phenomena. The condensed combustion products of flake aluminum powder are composed of dispersed gray-white particles, with multiple smaller fragments present. The smaller the particle size of the flake aluminum powder, the more dispersed its combustion products appear upon solidification; conversely, larger particles tend to coalesce. The primary composition of the combustion products of flake aluminum powders consists of 3Al₂O₃·2SiO₂ and Al₂O₃ crystals. For spherical aluminum powders, both the combustion heat value and efficiency increase with larger particle size, with notable differences observed between nano-sized and micron-sized aluminum powders regarding combustion heat value and efficiency. The combustion products of spherical aluminum powders consist of closely adhered black and white condensed phase combustion products, along with a few gray-white particles distributed on the walls and bottom of the crucible. The ignition process of both flake and spherical aluminum powder composite fuels comprises five stages: ignition, deflagration, stable combustion, flame decay, and extinguishing, with significant effects of the microstructural differences in aluminum powders on each stage. The ignition delay time for flake aluminum powders is shorter than that for spherical aluminum powders, accompanied by a higher intensity of combustion, indicating greater flammability, while spherical aluminum powders exhibit longer combustion durations. Both flake aluminum powder composite fuels and spherical aluminum powder composite fuels can cause irreversible physical damage to chips and their leads, achieving effective destruction.