Effect of Process Parameters on the Properties of Direct Written Gas-Generating Reactive Layers

A mixture of copper complex and Al/CuO nanothermite, Al/CuO/CuC, represents one of the state-of-the-art gas-generating thermite systems with various pyrotechnic applications due to its tunable gas release rates. The reactivity of reactive inks with various loadings of the poly(vinylpyrrolidone) (PVP) binder mixed with Al/CuO/CuC is characterized using high-speed imaging diagnostics and pressure measurements. For a PVP mass fraction of <7 wt %, the printed materials remain highly reactive and burn at a high velocity (10–54 m/s), which was one of the important goals of this study. At higher PVP contents, the polymer inhibits the reaction. Printing (dropwise and continuously writing) of inks containing 5 wt % PVP and 95 wt % reactive Al/CuO/CuC powder was demonstrated using a volumetrically controlled dispenser and a pneumatically actuated syringe. The pressure development and burning rate of the printed materials are 0.37 MPa (at 46.3% theoretical maximum density (TMD)) and 17 m/s (at 0.24% TMD), respectively, more than 10 times faster than the majority of works dealing with printed energetic formulations.