Effects of Sintering Behaviors on Dimensional Accuracy, Surface Quality, and Mechanical Properties of Stereolithography-printed 3Y-ZrO2 Ceramics

Sintering process is essential to acquire the final components by stereolithography (SLA), which is a promising additive manufacturing technology for the fabrication of complex, custom-designed dental implants. 3Y-ZrO2 ceramics at different sintering behaviors in air atmosphere were successfully obtained in this study. Firstly, the curing properties of homemade pastes were studied, and the penetration depth and critical exposure of the pastes were calculated as 17.2 μm and 4.80 mJ/cm2, respectively. The green ceramic parts were performed at 154 mW laser power and 6000 mm/s scanning speed. Then, the dimensional accuracy, surface quality, and mechanical properties of 3Y-ZrO2 ceramics were investigated. The shrinkages of length, width, and height were 26%~27 %, 30%~31 %, and 27%~33 % in sintered ceramics, respectively. The Ra values of XOY, YOZ, and XOZ surfaces showed an anisotropic feature, and they were smallest as 0.52 μm, 2.40 μm, and 2.46 μm, respectively. Meanwhile, the mechanical properties presented a similar trend that they grew first and then dropped at various sintering behaviors. The optimal parameters were 1500 ℃, 60 min, and 4 ℃/min, and the maximum relative density of 96.18 %, Vickers hardness of 12.45 GPa, and fracture toughness of 6.35 MPa·m1/2 were achieved. Finally, the X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) analysis demonstrated that no change was observed in crystal transformation and phase composition, and the organic was completely removed in sintered ceramics. This research is expected to provide a technical guide for the fabrication of ceramics for dental implants using SLA technique.