Influence of Nickel-Coating on the Thermal Oxidation Behaviors of Aluminum Powders

摘要

Aluminum powders with average diameters of 24, 45, and 75 mu m were homogeneously coated with nickel through an electroless plating process. The effect of nickel coating on the thermal oxidation behavior of the aluminum powders was clearly confirmed by observing the variation of the weight gain during thermal gravimetric analysis in an air atmosphere. The results obtained from differential scanning calorimetry showed that the exothermic enthalpy values of the aluminum powders increased significantly with decrease in the powder size from 75 mu m to 25 mu m. Furthermore, the nickel-coated aluminum powders exhibited much higher exothermic enthalpy values than those of pure aluminum powders. It was found that nickel coated onto aluminum powders plays an important role as a protective layer, preventing pure aluminum powders from undergoing surface oxidation while also providing exothermic heat through a self-propagating high-temperature synthetic reaction between the nickel and the aluminum. These results indicate that nickel coating should be considered to achieve high reactivity in aluminum powders for energetic applications.