Synthesis and characterization of porous Y2SiO5 with low linear shrinkage, high porosity and high strength

The emerging porous Y2SiO5 ceramic is regarded as a promising candidate of thermal insulator owing to its very low thermal conductivity. However, recent works on porous Y2SiO5 are confronted with severe problems such as large linear shrinkage (18.51-20.8%), low porosity (47.74-62%) and low strength (24.45-16.51 MPa) at high sintering temperatures (1450-1500 °C). In this work, highly porous Y2SiO5 ceramic with low shrinkage and excellent high-temperature strength was fabricated by in-situ foam-gelcasting method at 1550 °C. The as-prepared sample has unique multiple pore structures, low linear shrinkages of 6.3-4.5%, controllable high porosities of 60.7-88.4%, high compressive strengths of 38.2-0.90 MPa, and low thermal conductivities of 0.126-0.513 W/(m K) (porosity: 87.1-60.2%). The effects of relative density on relative strength, as well as porosity on thermal conductivity were quantitatively discussed. The present results indicate that porous Y2SiO5 is the potential high-temperature thermal insulation material of light weight, low thermal conductivity, and high strength.