Rheology and dispersion of silicon nitride into resin for slurries for vat photopolymerization printing and sintering

The development and rheology of resin-based slurries of silicon nitride for vat photopolymerization (VPP) using digital light processing (DLP) was investigated. A commercial resin, dispersants, and ceramic were used to make VPP slurry, and the efficacy of dispersants on zeta potential and rheology were tested with bimodal powder. This uncovered the behavior of commonly used VPP dispersants with silicon nitride in photopolymerizable resins. Shear thinning behavior was obtained with 40 vol.% solids loading, and the resulting cure depth was approximately 40 micrometers. Bend bars were printed, debound, and liquid-phase sintered. Microstructure and phases were characterized, and mostly beta phase silicon nitride (β-Si₃N₄) and mixed oxide phase were present. The samples reached high density and closed porosity. Flexural strength was approximately 330 MPa.