A novel aerogels/porous Si3N4 ceramics composite with high strength and improved thermal insulation property

A novel ZrO2-SiO2 aerogels/porous Si3N4 ceramics composite with high strength, low density, good dielectric properties and low thermal conductivity was synthesized by filling ZrO2-SiO2 aerogels into the porous Si3N4 ceramics through vacuum sol-impregnating. The effects of aerogels on the microstructure and properties of composite were discussed. The results show that aerogels could form a mesoporous structure and significantly decrease the thermal conductivity from 9.8 to 7.3 W m−1 K−1. Meanwhile, the density, mechanical and dielectric properties of the porous Si3N4 ceramics could not be affected after introducing ZrO2-SiO2 aerogels. The composite exhibits high porosity (62.6%), high flexural strength (53.86 MPa) and low dielectric constant (2.86). The ZrO2-SiO2 aerogels/porous Si3N4 ceramics composite shows great potential as radome materials applied in the fields of aerospace.