Abstract: Carbonyl iron powder (CIP) is a typical magnetic loss-type microwave absorbing material. However, its susceptibility to electrochemical corrosion in harsh marine environments (characterized by high humidity and salinity) leads to performance degradation, limiting long-term applications. In this study, core-shell particles (CIP@PFOTES) were fabricated via a sol-gel method, encapsulating CIP with a perfluorodecyltrimethoxysilane (PFOTES) shell. These particles were then incorporated into a fluorosilicone resin (FSR-ZY220L) to produce a multifunctional CIP@PFOTES-ZY coating. The coating exhibited superhydrophobicity with a water contact angle of 158°. A drag reduction exceeding 70% was achieved at shear rates ranging from 0.1 to 100 s^-1. The coating demonstrated excellent long-term corrosion resistance in a neutral salt spray environment. Electrochemical impedance spectroscopy (EIS) indicated that after 40 d of immersion in a 3.5 wt.% NaCl solution, the low-frequency impedance modulus (|Z|_0.01 Hz) remained above 10⁷ Ω cm². Furthermore, with a thickness of 1.3 mm, the coating achieved an effective absorption bandwidth (EAB, RL ≤ -10 dB) of 7.52 GHz, demonstrating significantly superior microwave absorption performance compared to the unmodified counterpart. This study provides an effective material design strategy for developing high-performance, multifunctional protective coatings for marine applications.

Key words: Carbonyl iron powder, Core-shell structure, Corrosion resistance, Microwave absorption, Drag reduction, Superhydrophobicity