Thermal and mechanical properties of fibrous zirconia ceramics with ultra-high porosity

Fibrous zirconia ceramics with ultra-high porosity (72-89%) were fabricated through a process of mixing the slurry of zirconia fibers and a binder, vacuum-molding and sintering the dried felt. The effects of binder content and sintering temperature on the microstructure, linear shrinkage, thermal and mechanical properties were investigated. The results showed that the zirconia fibers were bonded successfully mainly at the fiber junctions, and 10 wt% binder and 1600 °C were the optimal processing parameters for better properties. It was also found that the materials׳ room-temperature thermal conductivity and mechanical strengths varied with porosity linearly or exponentially, respectively. The sintered ceramics had a linear shrinkage of less than 2% after heating at 1600 °C for 1 h, a low density of 0.67-1.72 g/cm3, low thermal conductivity of 0.056-0.16 W/(m K), and relatively high compressive strength of 0.6-13.3 MPa. In addition, the material׳s high-temperature (up to 1400 °C) thermal insulation performance was also studied.