Enhancement of oxidation and corrosion resistance of flaky carbonyl‑iron powder via SiO2/KH560/PDMS coating applied with sol-gel

The popular magnetic material of flaky carbonyl iron (FCI) is unfortunately vulnerable to electrochemical corrosion when exposed to a salty and foggy environment. This work reports on a sol-gel method that successfully modifies FCI particles, using lithium silicate (Li2SiO3), poly dimethyl siloxane (PDMS), and γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH560), to synthesize Fe@SiO2@KH560@PDMS hybrid composite, related to its organic–inorganic hybrid coatings. The favorable hydrophobicity of organic–inorganic hybrid coatings with the static contact angle of 120° impeded the contact between corrosive medium and FCI core. The results of electrochemical experiments also confirmed its excellent corrosion resistance, since the corrosion potential Ecorr was positively shifted to 0.01 V, and the corrosion current Icorr was three orders of magnitude lower than that of the unmodified FCI particles. Thermogravimetric (TG) analysis indicates that the presence of hybrid coatings also improved the thermal stability of the produced material towards oxidation. Furthermore, the results of molecular dynamics simulation reveal that the hybrid layer inhibits the diffusion of corrosive medium.