Robocasting of silicon nitride with controllable shape and architecture for biomedical applications

Silicon nitride (Si 3 N 4 ) implants are used in spinal fusion surgery and are under development for use in other biomedical applications. The ability to create Si 3 N 4 implants with anatomically relevant shapes and controllable architecture can be beneficial in these applications. In the present study, an aqueous paste composed of Si 3 N 4 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 Si 3 N 4 phase (density=3.23±0.01 g/cm 3 ) 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 Si 3 N 4 implants with controllable shape and architecture for applications in orthopedic and dental surgery.