Thermal stability and reaction properties of passivated Al/CuO nano-thermite

Thermal stability and reaction properties of Al–CuO system, a mixture of 50–200 nm aluminum nanoparticles passivated by nitrocellulose and 12 nm copper (II) oxide, were investigated with microstructure characterization, differential thermal analysis (DTA), and thermogravimetric analysis (TGA). Transmission electron microscopy observation confirmed that the passivation coating successfully hinders the oxidization. TGA revealed that the passivation shell does not influence the ignition temperature of the thermite reaction. Reaction chemistry of the nano-thermite was elucidated by heating the composite both in inert ambient and vacuum. It was found that the thermite reaction composes of three continuing steps: At 570 °C, Al is oxidized into Al 2O 3 by reacting with CuO, which forms Cu 2O and produces a significant amount of heat. Subsequently two endothermic reactions occur. Starting at 800 °C, alumina reacts with Cu 2O and forms CuAlO 2. Above this temperature CuAlO 2 will decompose and eventually produce alumina, Cu, and O 2 at 1000 °C. Since the nano-thermite reaction pathway differs greatly from bulk thermite reactions, these results are important to develop a nano-thermite platform that can be used for a novel low cost, low temperature, and copper based microjoining and advance IC packaging. [Display omitted] ► We studied the thermal stability of nitrocellulose coated aluminum nanoparticles. ► We investigated the thermite reaction of coated aluminum and copper oxide nanoparticles .► We found the above nano-thermite reaction consists of three continuous steps.