Porous Y_2SiO_5 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 Y_2SiO_5 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 Y_2SiO_5were investigated.Compared with samples fabricated by direct sintering,porous Y_2SiO_5 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/cm^3,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 ℃.Porous Y_2SiO_5 has unique multiple pore structures,especially containing the interconnected small pores in skeleton.The thermal conductivity of porous Y_2SiO_5 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 Y_2SiO_5 with the potential application as high-temperature thermal insulation material.
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