Preparation and properties of ZrO2-strengthened porous mullite insulation materials using Y2O3 additive

ZrO2-strengthened porous mullite insulation materials were prepared by foaming technology utilizing ZrSiO4 and Al2O3 as primary materials and Y2O3 as an additive. The effects of Y2O3 contents on the phase composition, microstructure, mechanical properties, and heat conductivity of the porous mullite insulation materials were investigated. A suitable Y2O3 content could promote phase transition of monoclinic ZrO2 (m-ZrO2) to tetragonal ZrO2 (t-ZrO2), reduce pore size, and improve the strengths of as-prepared specimens. The cold crushing strength and bending strength of as-prepared specimens with a 119 mu m spherical pore size using 6 wt.% Y2O3 were 35.2 and 13.0 MPa, respectively, with a heat conductivity being only 0.248 W/(m K).