(435d) 3D Printing of Thermite Mixtures Using Static Mixing

Water-based solids-loaded inks are a general solution for 3D printing of functional materials, including reactive materials. While pre-mixed reactive materials inks are possible, it is desirable from a safety standpoint to formulate single-component inks which each contain only one reactant. These inks are essentially inert while separate and only achieve reactive properties when mixed, minimizing the quantity of reactive material present at any one time. We have been exploring various approaches to on-the-fly mixing of such single-component inks for 3D-printed reactive materials. In this talk, I will focus on Al/CuO thermites printed from single-component inks with on-the-fly “static” mixing. Commonly employed for two-part epoxies or dental materials, static mixers work by repeatedly “folding” two fluids together until they are intimately mixed. This is a useful alternative to dynamic mixing using a rotating paddle because it minimizes the energy input into the materials and thus the risk of premature reaction. The mixing quality is also less sensitive to variations in the printing speed. Our initial work has focused on demonstrating feasibility and identifying how much mixing, as characterized by the number of mixing elements, is required to achieve maximum thermite reactivity. After establishing the critical mixing conditions, we have explored some basic 3D-printed structures and begun to assess the impact of architecture on overall reactivity.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-733101