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.