Tunable EMW absorption properties of a novel SiC-SiO2/3Al2O3•2SiO2 composite ceramic

A kind of SiC-SiO2/3Al(2)O(3)center dot 2SiO(2) composite ceramic was successfully prepared by the technique of chemical vapor infiltration (CVI) for enhanced electromagnetic wave (EMW) absorption properties. Due to the weak EMW absorption performances of the pure SiO2/3Al(2)O(3)center dot 2SiO(2) ceramic, SiC nanocrystals as absorbers were introduced to improve the EMW absorption performances. The existences of SiC nanocrystals are beneficial for enhancing the EMW absorption performances, and the SiC-nanocrystal contents can be tailored in the SiO2/3Al(2)O(3)center dot 2SiO(2) ceramics. Although the SiC nanocrystals are helpful for the dielectric and EMW absorption properties, they are unfavorable for impendence matching owing to weak-absorption and strong-reflection if the SiC nanocrystals exceed the threshold value. According to the investigation, it can attain wonderful EMW absorption properties when the SiC-nanocrystal content is 77.1 wt% in the composite ceramic. The results show that the value of RC can reach -22.4 dB at 9.9 GHz, and the EAB is the complete X-band for the SiC-SiO2/3Al(2)O(3)center dot 2SiO(2) composite ceramics. And they can be tailored for the dielectric properties to obtain the excellent EMW absorption properties in the prepared SiC-SiO2/3Al(2)O(3)center dot 2SiO(2) composite ceramics. The mechanisms of EMW consumptions are Debye relaxation, dipole polarization, interfacial polarization, multi-reflection, multi-scattering and conductivity loss in the SiC-SiO2/3Al(2)O(3)center dot 2SiO(2) composite ceramics.

Automated summary

A SiC-SiO2/3Al(2)O(3)·2SiO2 composite ceramic was prepared with enhanced EMW absorption properties using CVI technique. SiC nanocrystals were introduced to improve the weak EMW absorption performances of pure SiO2/3Al(2)O(3)·2SiO2 ceramic, with the optimal content found to be 77.1 wt%. The mechanisms of EMW consumptions in the composite ceramics include Debye relaxation, dipole polarization, interfacial polarization, multi-reflection, multi-scattering, and conductivity loss.