Preparation of porous Y_2SiO_5 ceramics with relatively high compressive strength and ultra-low thermal conductivity by a TBA-based gel-casting method

摘要

Porous Y_2SiO_5 ceramics with relative high compressive strength (as high as 24.45 MPa) and ultra-low thermal conductivity (~0.08 W/ m K) were successfully fabricated by a tert-butyl alcohol based gel-casting method. The formation mechanism of the 3D interconnected pores and the properties of the green body are discussed. The porosity, pore size, compressive strength and thermal conductivity could be controlled by varying the initial solid loading and the sintering temperature. When regulating the initial solid loading (from 20 to 50 wt%) and sintering temperature (from 1200 to 1500 °C), the porosity can be controlled between 47.74% and 73.93%, and the compressive strength and the thermal conductivity of porous Y_2SiO_5 ceramics varied from 3.34 to 24.45 MPa and from 0.08 to 0.55 W/m K, respectively. It should be noted that the porous Y_2SiO_5 ceramics with 30 wt% solid loading and sintering at 1400 °C had an open porosity of 61.80%, a pore size of 2.24 μm, a low room-temperature thermal conductivity of 0.17 W/m K and a relatively high compressive strength of 13.91 MPa, which make this porous Y_2SiO_5 ceramics suitable for applications in high-temperature thermal insulators.