Enhanced reactivity of mechanically-activated nano-scale gasless reactive materials consolidated by coldspray

The present study presents a novel method to prepare nano-scale energetic materials with high reactivity, low porosity and controllable shape. The experiments have been focused on the Ni–Al system. To increase the reactivity, an initial mechanical activation was achieved by the ball milling technique. The consolidation of the materials was achieved via the use of the Cold Gas Dynamic Spray (also known as Cold Spray) technique, where the particles are accelerated to high speeds and consolidated via plastic deformation upon impact, forming activated nanocomposites in arbitrary shapes with porosity levels close to zero. This technique permits to retain the powder microstructure in the coatings and prevents any reactions during the consolidation phase. The material reactivity is addressed through the flame propagation velocity, which showed an increase in the flame speed of the cold sprayed samples by up to one order of magnitude compared to their cold pressed counterparts.

► We studied the SHS reaction rate of Al–Ni intermetallic mixture. ► Ball milling of the materials improved the reaction rate. ► Coldspray process allowed manufacturing fully dense coatings. ► The Helium spray at 300 °C does not trigger the SHS reaction. ► Vanishing of porosity increase the reaction rate by an order of magnitude.