Preparation of SnO2-coated carbonyl iron flaky composites with enhanced microwave absorption properties

The SnO2-coated carbonyl iron (CI) (SCCI) composites were synthesized by combining ball milling and mild hydrothermal treatment and their microwave absorption performance at 2–18 GHz was evaluated. The results showed that the microwave absorption properties of SCCI were improved remarkably due to the existence of the uniform coating of SnO2 on the surface of the flattened CI particles. The strongest reflection loss (RL) of SCCI reached −57.8 dB with a thickness of 8.3 mm at 12.1 GHz, and strong absorption (RL<−10 dB) was obtained between 7.2 and 18 GHz with the thickness of 7.0–13.0 mm. Furthermore, at a low thickness of 2.0–2.9 mm, the SCCI still showed strong microwave absorption property and its maximum RL value reached −20.5 dB with a thickness of 2.3 mm at 15.7 GHz. This SCCI composites possessed excellent microwave absorption properties and could become a promising candidate for the application of microwave absorption.

► SCCI was fabricated by combining ball milling and mild hydrothermal treatment.
► Flaky CI was uniformly coated with SnO2 particles.
► Microwave absorption property of CI was markedly enhanced thanks to the SnO2 coating.