Reactivity of nanothermite-based micro energetic sticks prepared by direct ink writing

Direct ink writing (DIW) is an important platform for integrating nanothermites into micro-energetic arrays for functional applications in micro-energetic devices. Energetic sticks act as the basic units of these energetic arrays, but the diameter dependency of their laser ignition threshold is not well understood. Additionally, their combustion propagation behavior at the micro scale has yet to be illuminated. In this study, five typical nanothermites-CuO/Al, Fe2O3/Al, Co3O4/Al, MnO2/Al, and Bi2O3/Al-were used to prepare energetic sticks with various diameters through a DIW platform, and their ignition and combustion propagation behavior was investigated at the micro scale. The results demonstrated that the relationship between the stick diameter and laser ignition threshold was nearly linear and dominated by the reactant characteristics. Furthermore, the combustion velocities of most of the energetic sticks (except Bi2O3/Al and Fe2O3/Al) could be regulated by modulating the diameter within certain limits, while combustion termination appeared in the propagation process of Bi2O3/Al-based energetic sticks with diameters ranging from 0.25 mm to 0.84 mm. Additionally, plateaus with diverse ranges appeared in the combustion velocity-stick diameter curves of the CuO/Al, Co3O4/Al, and MnO2/Al samples. Bend propagation tests demonstrated that all samples, except for Bi2O3/Al, possessed the capability of turning corners below 120, while the jumping ignition occurred in the CuO/Al, Co3O4/Al, and MnO2/Al samples above 135 at a diameter of 0.58 mm. These results on the laser ignition and combustion propagation behavior of energetic sticks at the micro scale could provide a reference for optimizing core materials or array assemblies in micro-energetic devices.

Automated summary

This study investigates the laser ignition and combustion propagation behavior of energetic sticks at the micro scale, prepared through a direct ink writing (DIW) platform. The relationship between stick diameter and laser ignition threshold is nearly linear and dominated by reactant characteristics. Most energetic sticks can have their combustion velocities regulated by modulating the diameter, but combustion termination may occur under certain conditions. The combustion velocity-stick diameter curves exhibit plateaus with diverse ranges, and the samples have different capabilities in terms of turning corners and jumping ignition at specific diameters.