A synergistic dispersion strategy for high volume fraction slurry and high performance silicon nitride sintered components in digital light processing (DLP)-based vat photopolymerization

The digital light processing (DLP)-based vat photopolymerization enables the fabrication of intricate silicon nitride (Si3N4) components. However, challenges still persist in producing low-defect and high-performance ceramic parts at lower volume fractions. In this study, a new block copolymer was employed for the modification of Si3N4 powders. The rheological behavior, dispersant mechanism, curing properties, printing performance of green body, mechanical properties and Weibull modulus of the sintered sample were systematically investigated. The results indicated that the modifier characterized by the long molecular chains and C=C double bonds adhered successfully to the surface of Si3N4 particles through hydrogen bonding, and the viscosity reduction effect of this modifier was ten times lower than that of the reported KH560 modifier. Besides, the synergistic dispersion effect achieved via the combination of the long chain modifier with a small molecular dispersant, facilitates the preparation of a 60 vol.% (80.74 wt.%) Si3N4 slurry. Subsequently, the tightly bonded interlayer of the green body and the complex Si3N4 sintered components with different volume fractions, high consistency and superb mechanical performance (the strength of 865.87 ± 54.35 MPa and the Weibull modulus of 18.49) were fabricated. These findings highlight the promising potential of the proposed modification approach for advancing the fabrication of high volume fraction and high-performance Si3N4 components.