Systematic optimization of silicon nitride slurries for high-precision photopolymerization 3D printing

Silicon nitride ceramics demonstrate significant promise for additive manufacturing, particularly in the fabrication of complex geometries. However, challenges such as a high refractive index and natural hydrophilicity hinder the stability and printability of Si 3 N 4 slurries for vat photopolymerization-based stereolithography. This study addresses these limitations by optimizing slurry parameters, including viscosity, sedimentation stability, and curing depth, to enhance printing performance. A systematic investigation was conducted using the Taguchi method to analyze the effect of solid content, dispersant concentration, and resin ratio on slurry behaviors. Rheological analysis revealed shear-thinning behavior in all tested slurries, a characteristic that facilitates smooth and uniform layer deposition during printing. Sedimentation and stability tests over 50 days identified a slurry formulation with 50 vol% solid content, 3 wt% dispersants, and a 1:2 resin ratio as optimal for minimizing sedimentation and ensuring homogeneity. Curing depth analysis indicated that increased solid content reduces light penetration due to scattering, necessitating a carefully balanced formulation. The addition of E51 resin enhanced light penetration and slurry uniformity, optimizing the curing process. The optimized slurry formulations enabled the precise 3D printing of complex green bodies, achieving excellent layer adhesion and dimensional accuracy. This study establishes a detailed framework for enhancing the printability of Si 3 N 4 slurries, addressing key challenges associated with viscosity, stability, and curing behavior, and advancing the application of non-oxide ceramic in additive manufacturing.