Broadening the debinding temperature window by PEG addition to reduce defects and improve the mechanical properties of vat photopolymerized alumina ceramics

To address the critical challenges of narrow debinding window and defect formation in vat photopolymerization (VPP) 3D-printed alumina ceramics with high resin content (as high as 50 vol%), this study introduces polyethylene glycol (PEG400) as an auxiliary organic phase. The concentrated thermal decomposition of the single-resin system, typically occurring within a sharp temperature range of 300–500 °C, was transformed into a stepwise process spanning 200–500 °C by PEG pre-decomposition. This window broadening of ∼100 °C facilitated early gas release through interconnected pore channels formed at low temperatures, thereby alleviating internal pressure and stress accumulation during main resin decomposition. Quantitative X-ray computed tomography analysis confirmed significant defect suppression, with the 10 vol% PEG group (P1) achieving the lowest average defect volume and delamination fraction. Consequently, sintered samples exhibited 30% improvement in flexural strength (234 MPa) and 97.1% relative density. These results demonstrate that broadening the debinding temperature window is an effective strategy for defect control and mechanical property enhancement in VPP ceramics.