A microwave-absorbing and corrosion-resistant integrated coating based on corrosion inhibitor-collaborative silica-encapsulated carbonyl iron particles

Most magnetic microwave absorption coatings are susceptible to corrosion under high-humidity, high-salt spray conditions, posing a significant threat to the survival and service life of maritime military equipment such as naval vessels. Therefore, the development of integrated stealth and anti-corrosion coatings is of paramount importance and urgency. This work presents an integrated coating utilizing a core-shell structured composite material (CIP@SiO2-M16) as the filler, based on the synergistic combination of M16 corrosion inhibitor and SiO2 shell encapsulation of carbonyl iron core particles. Experimental results demonstrate that the SiO2 shell on the surface of CIP, along with the chelation between adsorbed M16 and CIP, hinders the contact and reaction of corrosive ions with CIP. Simultaneously, the presence of the shell inhibits the formation of conductive pathways between CIP particles, leading to a reduction in the complex permittivity and optimizing impedance matching, allowing more electromagnetic waves to penetrate the coating's interior and be absorbed. As a result, this coating exhibits exceptional corrosion resistance and microwave absorption performance, with an electrochemical impedance of up to 2.38 × 109, over 1056 h of alternating salt spray exposure, and an unprecedented effective absorption bandwidth of 7.4 GHz at only 1.3 mm thickness, showcasing significant application potential. We believe that this coating's development opens up new avenues for research in the field of integrated stealth and corrosion resistance.