Dependence of the bending properties of alumina on the in‐plane printing orientation in direct ink writing

Abstract The additive manufacturing (AM) of ceramic bodies often affords structural and mechanical anisotropies depending on the printing orientation and building direction. Thus, in this study, we investigated the influence of in‐plane printing orientation on the bending properties of alumina fabricated via direct ink writing (DIW), an AM technology. Additionally, the DIW fabrication and pretreatment of green bodies were conducted to eliminate the voids between filaments and surface irregularities to focus on individual filament orientation. Bar specimens were sintered at 1200°C to preserve the as‐printed microstructures, achieving relative densities of 77% irrespective of the printing orientation. Furthermore, the sintering shrinkage, bending modulus, and bending strength were 11%, 190 GPa, and 150 MPa, respectively, unaffected by the printing orientation. Additionally, minor variations in shrinkage and strength were attributed to the orientation‐independent phenomena. These findings indicate that the DIW‐printed alumina can be treated as an isotropic material, and the structural analysis of DIW‐printed alumina products should focus only on the defects resulting from the DIW process.