Rational design and fabrication of hierarchical ceramics using bioinspired microstructures for tailorable strength and toughness

Abstract

Dense bioceramics feature hierarchical microstructures with weak interfaces that endow them with strength, toughness, and structural functionalities. Conversely, most technical ceramics possess limited structural complexity and strong grain boundaries that restrict their toughness and functions. Here, we report a rational design strategy to fabricate ceramics with various bioinspired microstructural motifs, leading to strength, toughness, and locally varying properties. We employ magnetically assisted slip casting (MASC) for local orientations of alumina microplatelets and ultrafast high-temperature sintering (UHS) as a densifying method. We sequentially vary the slurry composition and sintering processes to attain high texture, relative density, and weak grain interfaces. We realize dense ceramics with horizontal, periodic, and graded motifs that exhibit direction- and site-specific properties, with flexural strengths of ∼290, 155, and 215 MPa, and fracture toughness of ∼7, 5, and 10 MPa·m^0.5, respectively. The strategy could be used to fabricate ceramic composites for tailorable local and bulk properties.