Synergistic effects of decarbonization and presintering on the thermal conductivity of Si₃N₄ ceramics in vat photopolymerization

Silicon nitride (Si₃N₄) ceramics are ideal for thermal management but often suffer from limited thermal conductivity due to oxygen impurities. In vat photopolymerization (VPP), pyrolytic carbon (PyC), a byproduct generated during the debinding process, is traditionally viewed as a harmful impurity. This study presents a pioneering "waste-to-wealth" strategy that repurposes in-situ PyC as an oxygen getter, unlocking its potential to enhance the thermal conductivity of Si₃N₄ ceramics. By adjusting these parameters, a maximum thermal conductivity of 92.18 W·m⁻¹ ·K⁻¹ was achieved with decarbonization at 450 °C and presintering at 1350 °C. This represents a 17.29% enhancement compared to the baseline debound in air without presintering. This enhancement is attributed to the synergistic interplay of reduced oxygen content, a strategically isolated intergranular phase, and a carbon-modulated grain orientation that mitigates the detrimental effects of misaligned a/b-axis grain boundaries. Our findings demonstrate a new strategy to enable performance customization in additively manufactured ceramics.