Ultrahigh-Strength Porous Ceramic Composites via a Simple Directional Solidification Process

Porous ceramics possess great application potential in various fields. However, the contradiction between their pores and their strength have significantly hampered their applications. In this study, we present a simple directional solidification process that relies on its in situ pore forming mechanism to fabricate Al₂O₃/Y₃Al₅O₁₂/ZrO₂ porous eutectic ceramic composites with a highly dense and nanostructured eutectic skeleton matrix and a lotus-type porous structure. The flexural strength of this porous ceramic composite with a porosity of 34% is 497 MPa at ambient temperature, which is a new record of the strength of all current porous ceramics. This strength can remain at 324 MPa when the temperature increases up to 1773 K because of its refined lamellar structure and strong bonding interface. We demonstrate an interesting application of the directional solidification in efficiently preparing the ultrahigh-strength porous ceramic with high purity. The findings will open a window to the strength of porous ceramics.