Hierarchical porous MgAl₂O₄ ceramic in situ structured by hollow particles: Low-shrinkage and high-strength

Porous MgAl₂O₄ ceramics exhibit a wide range of applications in various fields, but their significant shrinkage and low strength at high porosity levels serve as impediments to their continued advancement. This study presents the first instance of synthesizing hollow MgAl₂O₄ particles in situ within porous ceramics through the utilization of the Kirkendall effect and solid-state reaction. The formation of a hollow structure results in volume expansion, which effectively mitigates sintering shrinkage while simultaneously generating a hierarchical pore structure within the material. This approach led to a significant improvement in compressive strength. Upon reaching a sintering temperature of 1600°C, the obtained sample has a porosity of 92.86%, a compressive strength of 4.17 MPa, and a shrinkage rate of only 5.21%. The findings suggest that the employed technique is an effective approach for fabricating porous ceramics with superior performance.