Synergistic strengthening mechanism of zirconia-reinforced alumina ceramics through additive manufacturing and sintering

Abstract

Fabricating high-strength ceramics with high precision intricate shapes from photosensitive ceramic slurry is an exciting yet challenging due to limited control over sub-grain structures, performance and sustainable manufacturing. Herein, to address these issues, a high solid content 50 vol% zirconia-reinforced alumina (ZRA) ceramic suspension with printable built-in functionality is proposed, enabling customizable target recognition, and enhanced flexural strength performance. Using stereolithography 3D printing with an optimized low shear rate suspension, precise printing control over tuned physical properties, morphology engineered structures and significantly enhanced performance with different holding time were obtained. With the ZrO₂ reinforcement strategy, this study not only demonstrates high flexural strength and hardness but also minimization of shrinkage. After sintering at 1550 °C for 6 h, the density reached a maximum of 98.7 % with shrinkage 7.57 % along the XY direction and 16.33 % along Z direction. Remarkably, the sintered ZRA ceramic exhibited a flexural strength of 371.8 ± 5 MPa, Vickers hardness of 1198. 2 ± 1.6 HV, and compressive strength of 33.54 MPa. Microscopic and tomographic analysis revealed a two-phase microstructural nature that enhances toughness and promotes good distribution. Benchmark strength is enhanced because of the improved interfacial bonding and fine-grained structure, which is the most dominant contributor to the mechanical properties. The findings set a guideline for high strength property-structure relationship of DLP-3D printed alumina reinforced composites in the field of advanced ceramic industry.