Preparation of high-performance ZrO2 bio-ceramics by stereolithography for dental restorations

Stereolithography (SLA) 3D printing technology is an advanced technology with great advantages and prospects in the field of dental repair that needs personalization and high precision. In this work, we tried to optimize the printing parameters, including laser power, scanning space, and layer thickness, from the dimension accuracy, warpage, and surface quality of the prepared samples and focus on the research and optimization of the debinding process in the heat treatment process. Starting from dimensional accuracy, warpage and surface quality, the optimal combination of printing parameters was 160 mW laser power, 0.07 mm scanning spacing and the ratio of layer thickness (Lt) to cured depth (Cd) was 1/3. In addition, it was found that the debinding atmosphere had a significant impact on the debinding effect of zirconia green body. The process of debinding in the nitrogen atmosphere and decarbonizing in the air atmosphere was finally adopted, which reduced the pyrolysis rate of organic matter, avoided the defects such as cracking of green body and bulging of sintered body, and improved the performance of ceramic samples. It was worth emphasizing that Vickers hardness, flexural strength and fracture toughness of the ZrO2 dental ceramics were 13.67 ± 0.72 GPa, 820 ± 59 MPa and 5.89 ± 0.63 MPa m1/2, respectively, and had good biocompatibility. The research results could provide some useful guidance for the selection of SLA printing parameters and the optimization of the heat treatment process.