The effect of sintering on the properties of calcium oxide promoted alumina-based ceramic cores via 3D printing

In order to aid dissolution of ceramic cores, calcium oxide was added to alumina to fabricate composite ceramics cores via 3D printing. The effect of sintering temperature and addition of calcia (5 wt%) on the microstructure and properties of the sintered ceramics were investigated. CaAl₁₂O₁₉ formed via a chemical reaction between alumina and calcium oxide at high temperature, and CaAl₁₂O₁₉ could be clearly seen in scanning electron microscope (SEM) images, energy dispersive X-ray spectroscopy (EDS) measurements, and X-ray diffraction (XRD) measurements. The sintered composite ceramics had porous structure and uniform elemental distribution. The sintered ceramics exhibit greater shrinkage, bulk density, and flexural strength when the sintering temperature is higher. The CaAl₁₂O₁₉ grains provide connections between alumina grains, which ensures the sintered ceramics have greater strength and less deformation compared to un-sintered ceramics.