Boosting corrosion resistance of carbonyl iron via silicon encapsulation

Abstract

Abstract Carbonyl iron is prone to electrochemical corrosion in environments such as salt spray, marine, or atmospheric conditions, leading to a decline in operational performance or even failure. In this study, tetraethyl orthosilicate (TEOS) and polydimethylsiloxane (PDMS) were used as raw materials, the silicon-encapsulated carbonyl iron composites were synthesized by dehydration condensation of silicon hydroxyl group of TEOS and terminal hydroxyl group of PDMS using a modified sol-gel method, aiming to bolster their corrosion resistance properties. The results of electrochemical experiments demonstrate that the CI@SiO2@PDMS composite exhibits excellent corrosion resistance. The corrosion potential is shifted in a positive direction to -0.11, accompanied by a significant reduction in the corrosion current by three orders of magnitude, down to 3 × 107. Furthermore, the electrochemical impedance modulus reaches a value of 1.3 × 105 Ω cm2, a magnitude that is nearly three orders of magnitude superior to that exhibited by the original iron powder. Additionally, the contact angle test reveals that the composite material possesses favorable hydrophobic properties. Therefore, the improved corrosion resistance observed in the composites can be ascribed to the inhibitory barrier effect of the modified layer and the hydrophobicity, which hinder the approach of corrosive ions.