High Heating Rate Reaction Dynamics of Al/CuO Nanolaminates by Nanocalorimetry-Coupled Time-of-Flight Mass Spectrometry

Highly tunable reactive nanolaminates have been of recent interest for various on chip energetic applications. The reaction dynamics of Al/CuO nanolaminates were investigated By nanocalorirnetry-coupled time-of-flight mass spectrometry, capable of simultaneous measurement of temporal thermal dynamics and detection of evolved gas phase species at heating rates up to 406 K/s. The nanolaminates were synthesized by alternately sputtering Al and CuO onto the heater of nanocalorimeter sensors. For thin films of 80 rim with -one bilayer, the stoichiorrietric ratio of fuel to oxidizer significantly affected the reaction mechanism: initial reactions Occurred between 300 and 400 degrees C, and main reactions varied 4 6 8 10 based-on stoichiometry. For thicker films of 199 and 266 nm, a series of samples with Varying bilayer numbers were analyzed to determine the-effect of diffusion distance and interfacial area. Only one reaction step was observed for a sample with a bilayer thickness of 33 mm A two-step reaction mechanism is observed as the bilayer thickness was increased to 66 nm and beyond: solid-state reaction occurring at the interfaces of Al and CuO Before the melting of Al and a much faster liquid solid reaction right after the melting of Al. At the same time, interfacial premixed distance during the deposition was also estimated from parallel experiments. Furthermore; the power data from nanocalorimetry provides a more direct method, compared to optical emission and mass spectrometry based methods, in determining the ignition temperature in Addition to being able to measure actual eriergy output for films with narioscale thicknesses.