Targeted design and analysis of microwave absorbing properties in iron-doped SiCN/Si3N4 composite ceramics

The SiCN(Fe)/Si3N4 composite ceramics containing C, beta-sic and alpha-Fe were designed by impregnating polysilazane followed by pyrolysis at 1-5 times with porous silicon nitride matrix. After the heat treatment, these new phases gradually formed and filled in the pores of the matrix to form a large whole. They bond together to facilitate the formation of conductive networks, which can improve the storage and transport capacity of the charge, thus improving the dielectric properties of the material. In this way, the highest dielectric and magnetic loss tangent values were achieved as 0.49 and 0.29 after third and fourth cycles, respectively. The electromagnetic wave can be absorbed similar to 80-90% in the range of 8-18 GHz with the thickness of 2 mm. The minimum reflectivity was -12.5 dB at 16 GHz with the thickness of 5 mm, showing >90% electromagnetic wave absorption at this frequency.

Automated summary

The SiCN(Fe)/Si3N4 composite ceramics with C, beta-SiC and alpha-Fe were designed to form conductive networks, improving charge storage and transport capacity, and enhancing dielectric properties. The material showed excellent electromagnetic wave absorption performance in a specific frequency range.