Surface passivation of applying an organic-inorganic hybrid coatings toward significantly chemically stable iron powder

Abstract Flaky carbonyl iron (FCI) is widely used magnetic material. The preparation of the FCI particles with excellent chemical and magnetic stability has attracted attention. In this work, the strategy to construct organic-inorganic hybrid shells was proposed through the sol-gel method on the surface of FCI particles. Hybrid layer with about 22.6 nm thick was obtained by the co-condensation between the tetraethylorthosilicate (TEOS) and perfluorooctyltriethoxysilane (PFOTES). The hybrid layer promotes the thermal stability of FCI. The corrosion of FCI was effectively suppressed in a 5% NaCl solution compared with uncoated and pure SiO2 coated group. The excellent corrosion resistance performance was partly ascribed to the reduced surface energy due to the presence of the perfluorooctyl chains. The maximum reduction in saturation magnetization (Ms) is only 7.58 % after coating with the hybrid layer. These results afford new insight into the manufacture carbonyl iron-based composites with better thermal stability, superior corrosion resistance, and acceptable magnetic stability.