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.

Progress in Additive Manufacturing of Energetic Materials: Creating the Reactive Microstructures with High Potential of Applications

“…To increase safety during processing, Murray et al proposed combinatorial or reactive inkjet printing [77], where two components of the reactive mixture are suspended in different inks and jetted sequentially. The authors demonstrated the value of this approach by depositing nano-Al (3.5 vol.…”

“…Another feature of additive manufacturing is the expanded capability of mixing the components. As discussed in the review, mixing can be performed during deposition by using several nozzles with their own inks, such as reactive inkjet printing [77] or sputtering in an alternative fashion [105]. More complicated design of the composites has been achieved with manufacturing of core-shell structures.…”

Development and Characterization of 3D Printable Thermite Component Materials

“…[5] This has been applied to control mechanical, [6][7][8][9][10] optical, [11][12][13] and electronic [14][15][16] properties of materials, as well as enable new functional materials. [21][22][23][24][25] RMs are a subset of energetic materials and are composites that, upon ignition, give rise to the rapid liberation of energy in the form of heat and/or pressure. [21][22][23][24][25] RMs are a subset of energetic materials and are composites that, upon ignition, give rise to the rapid liberation of energy in the form of heat and/or pressure.…”

“…[17][18][19][20] While a large portion of studies focus on quasi-static applications, additive manufacturing (AM) has also shown promise as a means to tailor dynamic properties, such as the rate of chemical energy release in reactive materials (RMs). [21][22][23][24][25] RMs are a subset of energetic materials and are composites that, upon ignition, give rise to the rapid liberation of energy in the form of heat and/or pressure. Further within the subset of RMs, materials can be defined as either intermetallics (metal/metal) or thermites (metal/metal oxide).…”

“…One factor in the choice of these precursors was to pick two systems that could be formulated with similar rheological properties, as disparate rheological properties could lead to potential issues during mixing operations. [21][22][23][24][25] RMs are a subset of energetic materials and are composites that, upon ignition, give rise to the rapid liberation of energy in the form of heat and/or pressure. The rheology of these high solids loaded prethermite inks had to be such that the inks could be extruded through a nozzle (i.e., shear thinning) as wet filaments.…”