Preparation and characteristics of porous anorthite ceramics with high porosity and high‐temperature strength

Abstract High‐temperature properties including compressive strength, thermal shock behavior, and thermal conductivity of porous anorthite ceramics with high specific strength were tested and analyzed. The results showed that the prepared materials merit high‐temperature compressive strength, thermal stability, and conductivity. With the appropriate fabrication parameters, even though containing 0.33 g/cm ³ bulk density and 88.2% porosity, its compressive strength could reach 2.03 MPa at 1000°C, 147% of that at room temperature; the residual strength ratio kept as 114.7% after a thermal shock at 1200°C. The X‐ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) showed that anorthite grains refinement and intergranular voids filling by liquid phase were main factors for the high strength. From room temperature to 1200°C, its thermal conductivity only varied from 0.085 to 0.258 W·(m·K) ⁻¹ . High porosity, a large number of nanoregions in anorthite grains and amorphous phase in grain boundary were main reasons for low thermal conductivity.