Time-Resolved Mass Spectrometry of Nano-Al and Nano-Al/CuO Thermite under Rapid Heating: A Mechanistic Study

Abstract

Aluminum nanoparticles (Al-NPs) and nano-Al/CuO thermite were investigated in a rapid heating environment by temperature jump time-of-flight mass spectrometry. Upon rapid heating (105 to 106 K/s), Al-containing vapor species (Al and Al2O) are observed to slowly increase with increasing temperature, followed by a rapid increase in concentration at ∼2030 K. The temporal evolution of Al, Al2O species observed in time-resolved mass spectra of rapid heated Al-NPs supports the hypothesis that Al containing species diffuse outward through the oxide shell under high heating rate conditions. The rapid rise in Al-containing species above 2030 K, which is below the bulk melting point of Al2O3, implies that the penetration of Al into the shell probably decreases its melting point. The measurements lead to an effective overall diffusion coefficient of ∼10–10 cm2/s. Time-resolved mass spectra of nano-Al/CuO thermite show for the first time the existence of Al, Al2O, AlO, and Al2O2 intermediate reaction products, with Al2O the main intermediate oxidation product, in agreement with thermochemical calculations.

Formation of Cu layer on Al nanoparticles during thermite reaction in Al/CuO nanoparticle composites: Investigation of off-stoichiometry ratio of Al and CuO nanoparticles for maximum pressure change

“…At the ignition point, we speculate that generated heat induces the gasification of reduced Cu. Experimental and theoretical studies have investigated the gasification process [15,31,32]. The gasified Cu is likely to travel toward unreacted neighboring area (e.g., pre-heated zone in Fig.…”

Assembly and reactive properties of Al/CuO based nanothermite microparticles

“…The details of the T-jump wire ignition experiments, and the operational setting can be found in our previous works [18,36,38]. Typically, a platinum filament of $11 mm long, 76 lm diameter coated with nanothermite sample ($4 mm long) was ramped to $1600 K in 3 ms, at a heating rate of $4 Â 10 5 K s À1 to ignite the sample.…”

Formation of Additive-Containing Nanothermites and Modifications to their Friction Sensitivity

“…Though mixing methods that achieve the intimate mixing of nano-dimensional fuel and oxidant in solvents are commonly used to produce nanothermites (Perry et al 2004;Puszynski, Bichay, and Swiatkiewicza 2010;Nellums et al 2013), the arrestive reactive milling of larger particles , solgel oxide synthesis (Tillotson et al 2001), and more complex methods that afford specific fueloxidant architectures are known (Shende et al 2008;Bahrami et al 2014). Many aspects of the nanoaluminum thermite reaction have been studied in detail, including aluminum melting and dispersion mechanisms (Levitas, Pantoya, and Dikici 2006;Firmansyah et al 2012;Jian, Piekiel, and Zachariah 2012), burning rate parameters (Asay et al 2004;Perry et al 2004;Yarrington et al 2011;Sullivan, Kuntz, and Gash 2014), and ignition methods (Pantoya and Granier 2005;Petre et al 2014;Shaw et al 2014). The current state of knowledge with regard to nano-aluminum production, oxidation, and thermite reaction has been recently reviewed (Rossi 2015).…”