Digital light processing 3D-printing alumina-based ceramic core with high porosity and available strength via adjusting sintering procedures

This work investigated sintering procedures for high-porosity alumina ceramic cores fabricated by digital light processing 3D-printing. Results showed that increasing sintering temperature reduced cristobalite while enhancing mullite formation. Flexural strength initially increased then declined with temperature, exhibiting an inverse relationship with porosity. Faster heating rates (up to 4°C/min) decreased mullite content and size, yielding peak strength of 23.73 MPa. Extended holding time reduced porosity but caused strength to first increase then decrease, peaking at 29.06 MPa. Optimal performance was achieved at 1450°C with 4°C/min heating and 120 min hold, producing cores with 28.28 MPa strength, 41.40% porosity, and 2.15 g/cm³ density. The process successfully balanced high porosity and mechanical properties at reduced temperatures.