Effect the Sintering Temperature on the Microstructure and Flexural Strength of ZrO₂ Ceramics Produced by...

Zirconia ceramics (ZrO₂) have received significant attention due to their excellent mechanical properties and broad application prospects. Additive manufacturing, especially nanoparticle jetting (NPJ), offers a new approach for fabricating zirconia ceramics with complex geometries. However, the sintering process plays a crucial role in determining the final properties of these ceramics, and the effect of sintering temperature on NPJ printed zirconia ceramics remains to be fully understood. This study investigates the impact of sintering temperature on the properties of zirconia ceramics fabricated via NPJ. NPJ-printed ZrO₂ green bodies were sintered at varying temperatures, and their phase composition, microstructure, and flexural strength were analyzed. Results show that as the sintering temperature rises from 800 °C to 1450 °C, the relative density of ZrO₂ increases from 55.0% to 98.3%, and the flexural strength rises from 9.3 MPa to 356.1 MPa. The green body consists of monoclinic (m-ZrO₂) and tetragonal (t-ZrO₂) phases, with m-ZrO₂ completely transforming into t-ZrO₂ at 1000 °C. Grain size also increases with temperature. The improvement in zirconia's flexural strength is primarily attributed to a combination of grain size and porosity. This research provides guidance for optimizing the sintering process of NPJ-printed ZrO₂ ceramics.