Effect of sintering aids on mechanical properties and microstructure of alumina ceramic via stereolithography

In this study, the effects of sintering aids (CaO, TiO2, La2O3 and ZrO2) on the physical and mechanical properties and microstructure of alumina ceramics made by stereolithography were systematically investigated. The addition of 3% CaO promoted internal porous structure at high temperatures, increasing the possibility of interlayer microcracking along the inner pores. 0.5% TiO2 had the best bending strength enhancement of alumina, increasing from 110.4 MPa to 201.1 MPa at a sintering temperature of 1650 °C. La2O3 took effect after 1550 °C and basically had no effect on refining grains. 1% ZrO2 increased 15% apparent porosity and 88% interlayer shear strength and reduced sintering shrinkage by about 30%, while maintaining bending strength. Optimised alumina powder ingredients and sintering conditions that could meet the performance index requirements of the ceramic core were obtained: particle size distribution 10 μm/2 μm (the mass fraction ratio of coarse to fine particles was 6:4), solid content 55%, sintering aid 1% ZrO2, sintering temperature 1450 °C.