Polyaniline-mediated hydrophobic modification of carbonyl iron powder (CIP) as durable and efficient electromagnetic absorbents with good corrosion resistance

Abstract

Carbonyl iron powder (CIP) is a widely used and commercially available functional material, but the susceptibility to electrochemical corrosion limits its application in humid and salty environments. In this study, a novel surface modification strategy that grafts stearoyl chloride on CIP with polyaniline (PANI) as the medium is developed to strengthen its anticorrosion performance. Modified CIP shows strong hydrophobicity and the static water contact angle can reach up to 141°. This surface modification increases the corrosion potential from −0.75 to −0.32 V and decreases the corrosion current from 6.3×10−6 to 5.0 × 10−7 A/cm2. After immersing in acidic NaCl solution for 240 h, modified CIP still exhibits powerful electromagnetic (EM) absorption performance, including strong reflection loss and broad absorption bandwidth, very close to that of pristine CIP. In contrast, CIP without surface modification presents a drastic reduction in EM function, especially reflected in narrow absorption bandwidth and increased matching thickness.