Optimization of the microstructure and properties of Al2O3-ZrO2 reticulated porous ceramics via in-situ synthesis of mullite whiskers and flowing-liquid phase

Abstract

Al2O3-ZrO2 reticulated porous ceramics (RPCs) with excellent properties and microstructure are prepared by using ceramic slurries coated polymeric sponges as novel organic templates. In this method, polymeric foams are first coated with slurries included AlF3, clay, α-Al2O3 and CeO2, before coating them with Al2O3-ZrO2 slurries, then calcined at 1480 °C for 3 h. The Al2O3-ZrO2 RPCs show a high strength and excellent microstructure. Meanwhile, the thermal shock resistance of the Al2O3-ZrO2 RPCs is improved significantly. This enhancement is attributed not only to the optimization of the microstructure, but also to the reinforcement of mullite whiskers. In addition, owing to the difference in the thermal expansion coefficients between mullite whiskers and matrix, the compressive residual stress can be formed within the matrix (tangential direction), which improves the thermal shock resistance of the resultant RPCs remarkably.