SiO2–modified APTMS nanocoatings encapsulating FeNi: Amplifying microwave absorption and corrosion resistance

Abstract

Corrosion is a major challenge for the reliable operation of ferromagnetic absorbers (FMAs) in extreme environments. Herein, we employed a one–pot method to construct SiO2–modified (3–Aminopropyl)trimethoxysilane (APTMS) nanocoatings on the FeNi surface, using tetraethyl orthosilicate and APTMS as precursors. The resulting APTMS/SiO2 nanocoating (thickness: 12.0–29.3 nm) contained numerous –NH2 and –OH functional groups, contributing to the generation of dipole polarizations. The nanocoating also improved the interfacial polarization and the impedance matching of FeNi@APTMS/SiO2, enhancing its microwave absorption (MA) properties. At 2.00 mm, FeNi@APTMS/SiO2 exhibited a maximum effective absorption bandwidth of 9.23 GHz, outperforming FeNi's 8.01 GHz. Moreover, the radar cross–section value of FeNi@APTMS/SiO2 reached as high as 27.84 dB·m2. Moreover, the nanocoating acted as a barrier to isolate the FeNi from the corrosive medium and prevent the formation of corrosive microcells with NaCl solutions, increasing the corrosion resistance of FeNi. The corrosion rate of FeNi@APTMS/SiO2 was measured at 4.71 × 10–11 m/s, which was 5.81 times lower than that of FeNi. This research highlights the advantages of APTMS/SiO2 for MA and corrosion protection, offering valuable insights into the development of corrosion–resistant FMAs.