Graphical Abstract

With the development of hypersonic vehicle technology, ceramic-based radome materials are highly demanded due to their high operating temperatures, good dielectric properties, and high mechanical properties. Although α-SiAlON is an ideal material for radome applications, its intrinsic low transmittance and high thermal conductivity limit its applications. Herein, we prepared Y–α-SiAlON porous ceramics through tert-butanol (TBA) gel-casting using the self-synthesized α-SiAlON powder. The Y–α-SiAlON porous ceramics exhibited a uniform micron-level connected pore structure with the porosity (P) of 44.2%–58.6%. The real part of permittivity (