Polymer‐derived Fe _x Si _y /SiC@SiOC ceramic nanocomposites with tunable microwave absorption behavior

Abstract Iron‐containing PSO precursors (FePSO) were synthesized by modification of polysiloxane with different amounts of ferric acetylacetonate [Fe(acac) ₃ ], then porous SiFeCO ceramics were successfully prepared by subsequent pyrolysis. The chemical modification and ceramization process of PFSO precursors were studied by FT‐IR and TGA measurements. XRD patterns imply that the SiC crystalline can be easily observed when PFSO was exposed to 1200℃ in nitrogen atmosphere, while pure PSO exhibited broad diffraction peaks of SiC at 1500℃, meaning that the grain coarsening of SiC was accelerated by adding iron. The crystallization behavior of ferric silicide (Fe _x Si _y ) is complex due to the variation of iron content in feed and annealing temperature, and Fe _x Si _y /SiC@SiOC nanocomposites were produced after annealing. Because of the in‐situ formation of SiC, Fe _x Si _y , and carbon strips in nanocomposites, PFSO‐derived ceramics demonstrate enhanced microwave absorption performance. The best effective absorption bandwidth (<−10 dB) and the minimum reflection loss are 2.6 GHz and −38 dB, respectively, which are achieved in the sample PFSO‐3–1300℃. Fe _x Si _y /SiC@SiOC nanocomposites synthesized in this work exhibit potential application in the field of electromagnetic interference, the carbon content and the crystallization behavior of Fe _x Si _y are the critical factors for the performance optimization.