Microstructure and properties of highly porous Y₂SiO₅ ceramics produced by a new water-based freeze casting

This study introduced a new structural/functional porous yttrium silicate (Y₂SiO₅) ceramic, which was prepared using a water-based freeze-casting technique. Moreover, the effects of sintering temperature on the microstructure, compressive strength, thermal conductivity, and dielectric properties of porous Y₂SiO₅ ceramics were investigated. The microstructure consisting of 3-D interconnected pores were created using the freezing process, and the formation mechanism was discussed. The microstructure observation indicated an increase in the sintering temperature from 1250°C to 1450°C and a decrease in porosity from 71% to 62%. In addition, the pore channel size decreased from 50μm to 25μm, but the average grain size increased from 1.0μm to 3.0μm. Consequently, the compressive strength, thermal conductivity, and dielectric constant of the porous Y₂SiO₅ ceramics increased from 3.34MPa to 16.51MPa, from 0.07W/mK to 0.22W/mK, and from 1.89 to 2.22, respectively. Porous Y₂SiO₅ ceramics with such properties can be applied to ultra-high temperature broadband radome structures and thermal insulators.