Fused deposition modeling of Si3N4 ceramics: A cost-effective 3D-printing route for dense and high performance non-oxide ceramic materials

Dense Si3N4 ceramics were prepared by fused deposition molding method accompanied by gas pressure sintering. In this study, the surface steps, inter layer bonding and microstructure evolution were characterized and dense Si3N4 ceramics without obvious defects were obtained. It was verified that layer thickness and nozzle diameter have little impact on the density and flexural strength of both green and sintered parts. As to the filling strategy, contour offset path was more effective to obtain sintered part with higher flexural strength than parallel lines and grid path, which was due to the possible voids appeared at the intersection of print paths with different di-rections. The highest flexure strength 824.74 +/- 85 MPa was obtained with layer thickness 0.15 mm, nozzle size 0.6 mm and contour offset path. The reliability of the obtained Si3N4 ceramics was also investigated and complex shaped Si3N4 ceramic parts with good shape keeping was prepared successfully.