Thermal Stability of Passivated Compacts from Pyrophoric Iron Nanopowders

Compact samples with diameters of 3 and 5 mm are prepared from pyrophoric iron nanopowder in a glove box in an argon atmosphere, which are placed in bottles with a ground-in lid. The iron nanopowder is obtained by the chemical-metallurgical method. The average size of the nanoparticles is 85 nm. It is established that during the exposure of the bottles with the samples to air, the samples were passivated with the preservation of their high chemical activity, since a combustion wave was launched over the sample at a rate of about 0.25 mm / s when the oxidation reaction was initiated by a high-temperature source. Exposure of passivated samples with a diameter of 5 mm for 60 min at a temperature of 110°С did not lead to a change in the phase composition of the sample. Exposure at a temperature of 180°С for 30 min led to a change in the color of the sample and its oxidation. The experiments with passivated samples with a diameter of 3 mm show that, under conditions of programmed heating, ignition of the samples occurs at a temperature of about 100°С. The conducted studies allow us to consider the obtained compact samples from an iron nanopowder thermally stable at temperatures below 100°C, when special temperature conditions are not required for their safe storage and transportation.