A multi-step reaction model for ignition of fully-dense Al-CuO nanocomposite powders

Correlating ignition mechanisms of aluminum-based reactive materials with thermoanalytical measurements

“…In addition, measurements with powders prepared using different milling conditions were also well described [147]. Combining CM model with the multi-step mechanism describing polymorphic phase changes and growth of different Al 2 O 3 polymorphs enables one to quantitatively reproduce TA measurements for the ARM-prepared powders for a broad range of temperatures [145].…”

“…Although the mechanism of the generation of the Mott potential across an interface produced between two solid reactants remains subject of active research [156], CM model was applied to such an interface earlier [157]. Following that work, and modifying the CM equations for an interface produced around a spherical oxide inclusion in a metal matrix [158], the CM model was applied to describe an early reaction in nanocomposite thermites produced by ARM [144,145,147,153,154]. Effectively, the CM reaction describes growth of the Al 2 O 3 film thickness h, as:…”

“…Instead, it is an effective thickness of a precursor phase, which transforms into Al 2 O 3 during the reaction. Detailed analyses of TA measurements focusing on the low-temperature reactions identified the CM model parameters, which are shown in Table 6 and describe such reactions for both Al$CuO [144,145,147] and Al$MoO 3 [153] nanocomposite thermites. Term E 2 , the contribution of the Mott potential, is treated as a linear function of temperature following Ref.…”

“…Additional experimental studies focusing on the lowtemperature reactions exploited isothermal and scanning microcalorimetry using a TAM III calorimeter by TA Instruments [144,145,153,154]. Reaction rates were quantified at temperatures as low as 303 K for Al$MoO 3 and Al$CuO thermites.…”

“…Ignition was considered for individual composite particles passing through a CO 2 laser beam and for a powder coated on an electrically heated filament [145]. In the laser ignition experiments, the minimum power of the CO 2 laser was identified, for which ignition of Al$CuO composite particles was observed.…”