Polymeric-filled alumina ceramics with enhanced fracture toughness

Highlights • A fracture toughness of 12 MPa for 45 % alumina composites – substantially exceeding values typically reported in the literature for similar densities. • Enhanced specific mechanical properties (toughness, strength, and modulus), underscoring the potential of these composites for lightweight structural applications. • Validation of toughening mechanisms through both experimental observation (SEM) and theoretical modeling. Abstract Ceramics’ toughening mechanisms have been an area of focus for many researchers. Although intrinsic toughening mechanisms reduce the need for a secondary structure, their performance has not yet matched that of extrinsic toughening mechanisms. This study investigates the mechanical properties of alumina ceramics filled with an epoxy matrix, prepared through a capillary suspension method. The method to fabricate the ceramics and corresponding composites is straightforward and scalable. Mechanical testing, including single-edge notch bending (SENB) and flexural, demonstrated significant improvements in fracture toughness, Young’s modulus, and tensile strength for the composite compared to porous ceramics and pure epoxy. The fracture toughness of 12 MPa for 45 % Al2O3 surpasses that reported in literature generally, and particularly for an equivalent density. SEM analyses identified primary toughening mechanisms such as particle pullout, crack deflection, and limited crack bridging. The density-normalized analysis highlighted the composite’s superior specific mechanical performance, emphasizing its potential for structural applications where the strength-to-weight ratio is critical.