Low-temperature exothermic reactions in fully dense Al–CuO nanocomposite powders

A hypothesis stating that the Cabrera–Mott kinetics describes low temperature redox reactions in fully dense nanocomposite thermite powders is explored. Earlier experiments involving differential scanning calorimetry (DSC) and new isothermal microcalorimetry measurements were interpreted using a reaction model employing the Cabrera–Mott mechanism. Following earlier work, the effect of Mott potential on the mass transport rate is considered to be temperature dependent. Simultaneous processing of both experimental data sets enabled us to determine parameters for the Cabrera–Mott mechanism describing the redox reaction in a nanocomposite Al–CuO thermite prepared by arrested reactive milling. The reaction model developed enables one to describe the initial portions of the DSC curves (up to 600 K) measured at different heating rates as well as microcalorimetry traces recorded in the temperature range of 303–413 K. The model is expected to be useful for describing both aging and ignition of fully dense, nanocomposite reactive materials.

► Mechanism of reaction leading to ignition in Al–CuO nanocomposite thermites studied.
► DSC and microcalorimetry measurements performed and interpreted with a single model.
► Utility of Cabrera–Mott kinetics to describe low-temperature redox reactions is shown.
► The mechanism will be useful for both ignition and aging modeling.