Effect of burying sintering on the properties of ceramic cores via 3D printing

In this work, 3D printed alumina green bodies were subjected to burying sintering using different alumina particle sizes to obtain ceramics. The effects of buried alumina particle size on the microstructure and properties of the sintered ceramics were investigated. The results showed that the shrinkage, density, and flexural strength of the ceramics increased as the alumina particle size increased from 5 μm to 1000 μm, but decreased as the particle size further increased to 2000 μm. The open porosity decreased as the alumina particle size increased from 5 μm to 1000 μm, but increased as the particle size further increased to 2000 μm. The sintered alumina ceramics were composed of layers, and interlayering spacing phenomenon was observed. The optimum particle size of buried alumina was 1000 μm, which resulted in sintered ceramics with shrinkage of 2.2 % in X direction, 2.1 % in Y direction, and 3.8 % in Z direction, density of 2.42 g/cm³, open porosity of 41.5 %, and flexural strength of 25.8 MPa. Buried powder sintering helped to support the green bodies, and also restrained the deformation of the sintered ceramics because the volatilization of the cured photosensitive resin compensated the vapor pressure in the environment. Compared with the ceramics sintered without buried powder, the ceramics subjected to burying sintering exhibited smaller shrinkage, lower bulk density, and higher open porosity. These features could not only diminish the deformation of the sintered ceramics, but could also facilitate the removal process in the manufacturing of hollow blades.