Corrosion-resistive magnetic powder Fe@SiO2 for microwave applications

Iron powder particles were coated with a thin SiO2 shell for protection of corrosion. Dynamic magnetic behavior of the as-synthesized material was studied in comparison with uncoated metal in terms of frequency dispersion of the microwave permeability and permittivity. A uniform 100-nm SiO2 shell provides durable corrosion resistance to a 4.5-mu m carbonyl iron powder. The shell was deposited through tetraethyl orthosilicate hydrolysis of technical grade chemicals. It was shown that the shell did not influence the magnetic properties of the iron powder. Electron microscopy, particle size analysis, and gamma-resonance spectroscopy were applied in the study. The deposited SiO2 decreased the microwave permeability value and prevented percolation conductivity in a composite with a paraffin wax dielectric matrix. (C) 2017 Elsevier B. V. All rights reserved.