Preparation and properties of porous Al2O3‐based ceramics by gel casting using MgO as a gelling and consolidating agent.

Low‐cost and environment‐friendly MgO was used as a new gelling and consolidating agent to fabricate porous Al2O3‐based ceramics via a gel casting routine. Effects of 800°C calcined additions of MgO (.5, 1.0, 1.5, and 2.0 wt%, respectively) on open porosity (OP), pore size distribution, gas flux, and microstructure of the porous ceramics were investigated deliberately. The experimental results showed that 800°C calcined MgO exhibits excellent gelling and consolidating performance at 80°C, mainly owing to the hydration reaction between MgO and H2O and thus results in high‐quality porous Al2O3‐based ceramics without deformation and cracking. The Al2O3–water suspensions with different MgO additions have good flowability at room temperature. Moreover, water absorption, open porosity, and gas flux of the as‐prepared porous ceramics increase remarkably with rising of MgO addition. Furthermore, MgO addition significantly suppresses the abnormal growth of Al2O3 grains, and thus the microstructure of the porous Al2O3‐based ceramics becomes more uniform. This technique of gel casting using MgO as a new gelling and consolidating agent offers an alternative routine for a large‐scale production of porous ceramics. [ABSTRACT FROM AUTHOR]