Abstract: Porous Y₂SiO₅ ceramic is a promising high-temperature thermal insulator in harsh environment. However, all the published relevant works faced serious problems, such as severe linear shrinkage, low porosity and low strength. In this study, porous Y₂SiO₅ ceramic with low sintering shrinkage and high porosity was successfully prepared by foam-gelcasting method using gelatin as the gelling agent. The effects of sintering methods, including in situ reaction sintering and direct sintering, and sintering temperatures on the phase composition, microstructure, shrinkage, porosity, and compressive strength of porous Y₂SiO₅ were investigated. Compared with samples fabricated by direct sintering, porous Y₂SiO₅ ceramic prepared via in situ reaction sintering method has the merits of the low linear shrinkage of 1.0%-4.7%, low bulk density of 0.79-0.88?g/cm³, high porosity of 82.1%-80.1%, and high strength of 3.54-8.03?MPa, when the sintering temperatures increase from 1350 to 1550?°C. Porous Y₂SiO₅ has unique multiple pore structures, especially containing the interconnected small pores in skeleton. The thermal conductivity of porous Y₂SiO₅ is very low, which is 0.228?W/(m⋅K) for the sample with a porosity of 79.6%. This work reports an optimal processing method of highly porous Y₂SiO₅ with the potential application as high-temperature thermal insulation material.

Key words: Porous Y2SiO5 ceramic, In situ synthesis, Mechanical property, Thermal property