In situ modification of Fe and Ni magnetic nanopowders produced by the electrical explosion of wire

摘要

Iron and nickel spherical magnetic nanoparticles (MNPs) with mean diameter 50-80 nm were prepared by the electric explosion of wire. The advantage of this method is that it provides a very high production rate up to 200 g/h and requires low energy consumption of 25 kW h/kg. The as-prepared MNPs were modified in situ in hexane, toluene, chloroform, and the solutions of polystyrene in toluene, in an inert atmosphere at room temperature in order to provide both the stability at ambient conditions and tunable surface properties. Hexane was an inert liquid for Fe and Ni MNPs. In the case of toluene the surface of as-prepared Fe or Ni MNPs acted as a catalyst for the condensation reaction of aromatic organic compounds forming irregular polycyclic structures. The treatment with toluene led to the deposition of carbon and formation of "hair-like" ordered structures on the surface of the MNPs. Chloroform chemically interacted with Fe MNPs, forming FeCl_2. The treatment of MNPs with the solution of polystyrene in toluene resulted in the adsorption of polymer and the formation of 3-6 nm polymeric coatings on the surface. The obtained magnetic properties (like the magnetization value for Ni MNPs up to 52 emu/g and Fe MNPs up to 179 emu/g) at room temperature make these MNPs competitive candidates for nanocomposites for microwave and other technological applications.