Polymer-derived FexSiy/SiC@SiOC ceramic nanocomposites with tunable microwave absorption behavior

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.