Vat photopolymerization-engaged fabrication of high-performance, complex Si3N4 implants under rapid debinding efficiency

In this study, the vat photopolymerization (VP) additive manufacture technique was employed to fabricate Si3N4 ceramics implants. A photosensitive suspension with a high solid loading of 40 vol% and a low viscosity of 1.95 Pa•s at a shear rate of 30 s−1 was achieved by optimization of the composition. Particularly, as high as 50 vol% content of PPG was used in the photosensitive suspension, leading to a smooth printing and increased debinding efficiency with a heating rate up to 3 °C/min. The printed body was sintered at 1800 °C under 0.4 MPa nitrogen atmosphere, obtained the Si3N4 ceramic with a relative density of 96.08%, a fracture toughness of 5.88 MPa·m1/2, a flexural strength of 677 MPa and a Vickers hardness of 16.26 GPa. A cylindric Si3N4 ceramic implant was made by the optimized suspension and printing parameters, and the implantation test in the histological section was conducted, showing a good biocompatibility after 6 weeks.