Microstructure and energetic characteristics of direct ink printed polymer-free rGO/nanothermite aerogel.

Aerogel, being extremely light and porous, is desirable for various applications of energetics such as a self-destructive microchip component. Additive manufacturing often requires a polymer binder which decreases thermal conductivity and changes combustion characteristics of the product. In this work, we fabricate a novel, polymer-free, reduced graphene oxide (rGO)-based Al/metal oxide nanothermite aerogel with a wide range of nanoparticle loading, via a new additive manufacturing process. SEM images revealed its unique porous structure formed by extra thin rGO sheets as the 3D skeleton, which wrapped Al and metal oxide nanoparticles into individual nanothermite clusters. DSC-TGA results and high-speed combustion videos confirmed the enhanced energetic performance of the printed specimen, suggesting the important role of rGO. A high linear burning rate of 5.8 m/s was achieved for a printed rGO/Al/metal oxide sample with a diameter of 1.6 mm (1/16") at 95 % thermite nanoparticle loading, and the propagation occurred at roughly the same rate with and against the print direction. This method allows for more complex 3D printing fabrication of various rGO/nanoparticle aerogels. Thermal camera footage clearly indicated the generation and increase of the pre-heating zone, reaction front, and cooling zone during the propagation. This method allows for more complex 3D printing fabrication of various rGO/nanoparticle aerogels. [Display omitted] • A novel room-temperature direct ink writing method for polymer-free rGO-nanoparticle aerogel. • Aerogel presents a unique porous structure and high nanoparticle loading up to 95 %. • Two different metal oxide nanoparticles were tested to develop nanothermite aerogel. • Fast and controllable linear combustion propagation rate between 10 cm/s and 5 m/s. • Increased heat transfer rate due to the highly conductive rGO scaffold. [ABSTRACT FROM AUTHOR]