Mechanical properties of β-Si3N4/SiCN ceramics formed by digital light processing

In this paper, polysilazane photocurable slurry with low viscosity and excellent rheological properties was prepared with β-Si 3 N 4 filler. Digital light processing (DLP) technique was utilised to form green bodies through optimized printing parameters. It was found that the introduction of β-Si 3 N 4 filler reduced the shrinkage and improved the mechanical properties of the polysilazane derived SiCN ceramics. The flexural strength of the resulted ceramics reached a maximum of 253.0 ± 15.1 MPa while 20 wt% of β-Si 3 N 4 powder was added, and the fracture toughness increased to 3.1 ± 0.3 MPa m 1/2  at 30 wt% of the β-Si 3 N 4 powder addition. The shape of the introduced β-Si 3 N 4 particles were believed to be faveriable for uniform dispersion in the printing slurry without agglomeration. In the following pyrolysis treament the β-Si 3 N 4 powders promoted the release of gaseous products so that maintained the structure integrety of the printed parts and the rod-like β-Si 3 N 4 particles enhanced the energy dissipation during ceramic fracture. In this study, silicon-based composite of β-Si 3 N 4 /SiCN ceramics with excellent mechanical properties were prepared by DLP additive manufacturing technology, which confirmed the feasibility and the great potential of photo-curing additive manufacturing technology in the manufacturing of SiCN ceramic matrix composites with complex structures.