Two-component additive manufacturing of nanothermite structures via reactive inkjet printing

Abstract

With an eye towards improving the safety of the deposition of energetic materials while broadening the scope of materials compatible with inkjet printing, this work demonstrates the use of combinatorial inkjet printing for the deposition of energetic materials. Two largely inert colloidal suspensions of nanoaluminum and nanocopper (II) oxide in dimethylformamide with polyvinylpyrrolidone were sequentially deposited on a substrate using piezoelectric inkjet printing. The materials were deposited in such a way that the aluminum and copper (II) oxide droplets were adjacent, and overlapping, to allow for in situ mixing of the components. The alternating deposition was repeated to create a sample with multiple layers of energetic materials. Energetic performance was subsequently tested on samples printed with 3, 5, and 7 layers of materials using a spark igniter. This ignition event was observed with a high speed camera and compared to representative samples printed with pre-mixed nanothermite. High speed thermal imaging supported a conclusion that the maximum reaction temperature of comparable samples printed with the dual nozzle technique was nominally 200 K less than the samples printed with a single nozzle. Scanning transmission electron microscopy images confirmed a claim that the material constituents were comparably mixed with the single and dual nozzle techniques. This work proves the feasibility of reactive inkjet printing as a means for depositing energetic materials from two largely inert suspensions. In doing so, it opens the doors for safer material handling and the development of a wide array of energetic materials that were previously deemed incompatible with inkjet printing.