Process development of fabricating ceramic core using 3D printing technique

Previous 3D printers developed for the fabrication of ceramic cores have been limited to implement mechanical properties and provide shapes that meet the requirements, since the type and size of powder, and the type of binder are standardized according to the printer. Therefore, in this study, the composition and manufacturing process of ceramic powder and binder were studied to fabricate ceramic cores with high mechanical properties without depending on the type of 3D printer. Fine mullite powder (average particle size: 16 mu m) and zircon flour (average particle size: 43 mu m) with conventional mullite bead. In addition, two types of polyvinyl alcohol (PVA) were used to enhance the coating ratio of an inorganic binder. Green bodies were formed by a three-dimensional (3D) printer employing three kinds of starting powders and PVAs mixed at the proper ratio. The green bodies were then heat-treated at 250 degrees C to evaporate the PVA with a lower boiling point. Then, the heat-treated core samples were dipped into the inorganic precursor, dried, and heat-treated at 1000 degrees C for the organic-inorganic conversion process. Through using a combination of different starting powders, the compact density of the sample was increased and the pore size was reduced, resulting in an increase in the coating efficiency of the inorganic binder. This study demonstrates the feasibility of the fabrication of a ceramic core with excellent strength through the 3D-printing process.