A novel SiC-based microwave absorption ceramic with Sc₂Si₂O₇ as transparent matrix

For enhancing the dielectric and electromagnetic wave (EMW) absorption ability, SiC-Sc₂Si₂O₇ ceramics were fabricated by introducing SiC into porous Sc₂Si₂O₇ ceramics through precursor infiltration and pyrolysis (PIP). The Sc₂Si₂O₇ powders were synthesized by sol-gel method and Sc₂Si₂O₇ ceramics were prepared by pressure-less sintering. The results indicate that SiC nano-crystalline and turbostratic carbon derived from polycarbosilane distributed uniformly in electrically insulating matrix (Sc₂Si₂O₇ matrix), resulting in tunable dielectric permittivity and EMW absorbing properties. Additionally, the content of C-rich SiC can be efficiently adjusted by PIP times. The SiC-Sc₂Si₂O₇ ceramic showed excellent microwave absorption performance when the content of C-rich SiC was 25.3 wt.%. A minimum reflection coefficient of −51.3 dB was obtained at 9.56 GHz with the specimen thickness of 3.6 mm. The effective absorption bandwidth covered 3.6 GHz (from 8.7 to 12.3 GHz). The excellent microwave absorption abilities of SiC-Sc₂Si₂O₇ ceramic were mainly attributed to uniform distribution of C-rich SiC in Sc₂Si₂O₇ matrix. The special structure can improve the impedance matching and enhance microwave absorption performance. Moreover, the defects, interfaces and conductive network existed in the materials, which can synergistically improve the EMW absorption ability.