Preparation and electromagnetic properties of composites of porous ceramics coated with NiFe₂O₄

The composites of porous SiC ceramics coated with NiFe₂O₄ (NFPC) were prepared using the polyacrylamide gel method. The structural characteristics，morphology and electromagnetic properties of the composites were analyzed by X-ray diffraction (XRD)，scanning electron microscope (SEM) and HP8510 network analyzer. The results indicate that a pure spinel structure of NiFe₂O₄ forms on the porous ceramics (PC) at 600℃. The uniformity and consistency of the nickel ferrite coatings on porous ceramics increase with the increase of the layer number of coatings. NFPC exhibits lower dielectric loss tanδ_ε and higher magnetic loss tanδ_μ compared with the porous ceramics matrix. Its tanδ_μ rises up to 0.45，which shows a better magnetic loss property. The tanδ_μ of NFPC decreases with the frequency in X band.