Porous gamma-(Yi(1-x)Ho(x))(2)Si2O7 thermal insulator with excellent high-temperature strength retention and very low thermal conductivity

摘要

High-temperature thermal insulation materials challenge extensive candidates with good mechanical, thermal and chemical reliability at high temperatures. Recently, porous gamma-Y2Si2O7 was indicated a promising thermal insulator in harsh environment; however, its strength at 1300 degrees C reduced to 34% of that at room temperature. In this work, we significantly improved its high-temperature strength by doping Ho. Highly porous gamma-(Y1-xHox)(2)Si2O7 solid solution was fabricated by in-situ foam-gelcasting method. Especially, porous gamma-(Y2/3Ho1/3)(2)Si2O7 demonstrated the optimal high-temperature strength, for instance 65% retention at 1300 degrees C, as well as high compressive strength (13.9 MPa) and low thermal conductivity (0.186 W/(m K)) at room temperature, at the porosity of 79.3%. Interestingly, porous solid solution sample displayed obviously lower thermal conductivity than the two end pure-phase porous materials. Porous gamma-(Y1-xHox)(2)Si2O7 solid solution is clearly highlighted as a promising high -temperature thermal insulator with outstanding high -temperature strength retention and optimal low thermal conductivity.