Preparation and Properties of Carbonyl Iron/Fe⁺²Fe₂⁺³O₄ with Oxidation Blackening

High-temperature stealth technology continues to face severe challenges, and the development of oxidation-resistant stealth materials is critical. In this work, complex absorbers of carbonyl iron/Fe⁺²Fe₂⁺³O₄ were prepared by an oxidation blackening method at room temperature, and the thermal stability of the complex absorbers was investigated. The effect of oxidation time on the chemical composition and surface morphology of the carbonyl iron was assessed. The electromagnetic and absorption properties of the composites before and after oxidation were analyzed, and results showed that the diffraction peak of Fe⁺²Fe₂⁺³O₄ increased after oxidation for 6 h at room temperature. Scanning electron microscopy coupled with energy-dispersive spectroscopy showed that the density of the Fe⁺²Fe₂⁺³O₄ increased, and the surface of the carbonyl iron was completely coated with Fe⁺²Fe₂⁺³O₄ after oxidation for 6 h. The complex permittivity increased and the complex permeability decreased by oxidizing blackening at room temperature. After oxidation for 6 h, the reflection loss of the composite was less than −5 dB in the whole X-band. The complex absorbers of carbonyl iron/Fe⁺²Fe₂⁺³O₄ prepared by oxidation blackening at room temperature have great application prospects in the field of radar stealth materials.