Characterization of Naturally Aged Iron Nanopowder Produced by Electrical Explosion of Wires

Abstract

Iron nanopowder obtained by electrical explosion of wires, passivated by air and stored for a long time (up to 18 years) under natural conditions are characterized. The characterization of iron nanopowder was made using X-ray diffraction analysis (XRD), scanning electron microscopy, X-ray fluorescent spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis and the test on flame propagation velocity in a bulk layer. XRD analysis revealed that the main crystalline phase in the studied powder is α-Fe. Iron oxide phases in the surface layer are amorphous. The crystalline iron oxide peak with low intensity was observed only in the powder after storage for 18 years. The iron nanopowder stored for a long time under natural conditions are found to be stable towards oxidation by air at ambient temperature. However, at the heating the iron nanopowder possesses high reactivity. Atmospheric air humidity is considered to be an important factor influencing the activity of iron nanopowder during heating and combustion.