Effect of NiFe₂O₄ filler on the wave-absorbing properties of PIP-SiC/SiCN composites

The SiC/SiCN composites demonstrate significant potential in aerospace, electromagnetic shielding, and other applications due to their exceptional high-temperature mechanical properties, wave absorption capabilities, and oxidation resistance. This study explores the effects of NiFe₂O₄ filler on the microstructure and electromagnetic wave absorption properties of SiC/SiCN composites synthesized using the polymer infiltration and pyrolysis (PIP) method. A range of characterization techniques, including TG-DSC, SEM-EDS, XRD, XPS, and Raman spectroscopy, were utilized to investigate the influence of NiFe₂O₄ content (ranging from 0 to 20 wt%) on the microstructure, chemical composition, and electromagnetic properties of the composites. The results reveal that the incorporation of NiFe₂O₄ significantly improves the density and uniformity of the microstructure. As the NiFe₂O₄ content increases, the real dielectric constant, real permeability, and electromagnetic loss of the composites exhibit a corresponding increase. The composite containing 15 % NiFe₂O₄ demonstrates optimal impedance matching characteristics and superior wave absorption performance at room temperature, achieving the lowest reflection of −19.6 dB in the X-band (8.2–12.4 GHz). High-temperature testing further indicates that the NiFe₂O₄ filler enhances the high-temperature electromagnetic wave absorption performance of the composites. Even at 700 °C, the 15 % NiFe₂O₄ composite maintains excellent wave absorption capabilities, with a minimum reflection of −18.12 dB. Additional analysis suggests that the NiFe₂O₄ filler improves wave absorption through multiple mechanisms, including enhanced conductive loss, polarization relaxation, and magnetic loss. These findings provide valuable insights and experimental evidence for the development of high-performance, wideband, high-temperature electromagnetic wave absorbing materials.