Development of multicolor 3D-printed 3Y-ZrO₂ sintered bodies by optimizing rheological properties of UV-curable high-content ceramic nanocomposites

UV-curable different-colored 3Y-ZrO₂ ceramic nanocomposite resins with a ceramic content of 50 vol% were prepared for supportless stereolithography 3D printing. Based on the correlation between the solubility parameters of UV-curable organic resin systems and the rheological behaviors of highly loaded ceramic nanocomposites, the physical properties of the different-colored 3Y-ZrO₂ ceramic nanocomposite resins, such as photocurability, viscosity, flowability, and printability, were optimized for a supportless 3D printing process. Thus, white, pink, yellow, and gray 3Y-ZrO₂ ceramic nanocomposite resins with optimum physical properties were prepared. The different-colored 3D-printed 3Y-ZrO₂ objects sintered at 1450 °C for 180 min exhibited a high relative density of>99.90% and a high flexural strength of>930 MPa, which are comparable to those of commercial 3Y-ZrO₂ manufactured by a conventional ceramic process. In addition, gear-shaped objects with different-colored layers of ceramic resins were successfully manufactured by continuous 3D printing and simultaneous sintering. This study paves the way for innovation in the manufacturing of ceramic products by 3D printing as an alternative to the traditional ceramic process.