Robocasting of Silicon Nitride with Controllable Shape and Architecture for Biomedical Applications

Silicon nitride (Si3N4) implants are used in spinal fusion surgery and are under development for use in other biomedical applications. The ability to create Si3N4 implants with anatomically relevant shapes and controllable architecture can be beneficial in these applications. In the present study, an aqueous paste composed of Si3N4 powder and sintering additives was prepared with the requisite rheology and formed into structures with different geometry and architecture using a robocasting technique. Sintering and hot isostatic pressing produced an almost fully dense Si3N4 phase (density=3.23±0.01 g/cm3) with a fibrous microstructure. Four-point bending tests of as-fabricated dense beams showed a flexural strength of 552±68 MPa. Together, these results indicate that robocasting combined with sintering and hot isostatic pressing can provide a viable manufacturing approach to create Si3N4 implants with controllable shape and architecture for applications in orthopedic and dental surgery