Alumina-based ceramic cores with high porosity and flexural strength fabricated via DLP 3D-printing

Alumina-based ceramics are regarded as the ideal material for ceramic cores owing to their outstanding high-temperature properties. In this work, digital light processing (DLP) was adopted to form complex alumina-based core structures with polymethyl methacrylate (PMMA) microspheres as pore-forming agent. The influence of PMMA content and sintering temperature on the physical properties, flexural strength, and microstructure of alumina-based ceramics was investigated. The results showed that with the increase of PMMA content and decrease of sintering temperature, the porosity of ceramic cores gradually increased, whereas the flexural strength decreased. The flexural strength of ceramics was enhanced by the synergistic effect of SiO 2 and TiO 2 sintering aids, and PMMA microspheres also effectively formed a large number of pores. The most optimal structural characteristics (porosity of 50.48% and flexural strength of 46.77 MPa) were achieved, via sintering of alumina-based ceramics at 1200 °C with the addition of 20 vol% PMMA microspheres.