Preparation of Si3N4 ceramic based on digital light processing 3D printing and precursor infiltration and pyrolysis

The emergence of digital light processing (DLP) 3D printing technology creates favorable conditions for the preparation of complex structure silicon nitride (Si3N4) ceramics. However, the introduction of photosensitive resin also makes the Si3N4 ceramics prepared by 3D printing have low density and poor mechanical properties. In this study, high-density Si3N4 ceramics were prepared at low temperatures by combining DLP 3D printing with precursor infiltration and pyrolysis (PIP). The Si3N4 photocurable slurry with high solid content and high stability was prepared based on the optimal design of slurry components. Si3N4 green parts were successfully printed and formed by setting appropriate printing parameters. The debinding process of printed green parts was further studied, and the results showed that samples without defects and obvious deformation can be obtained by setting the heating rate at .1 degrees C/min. The effect of the PIP cycle on the microstructure and mechanical properties of the Si3N4 ceramics was studied. The experimental results showed that the mass change and open porosity of the samples tended to be stable after eight PIP cycles, and the open porosity, density, and bending strength of the Si3N4 ceramics were 1.30% (reduced by 97%), 2.64 g/cm(3) (increased by 43.5%), and 162.35 MPa.