Improvement in collapsibility of ZrO₂ ceramic mould for investment casting of TiAl alloys

Investment casting has been widely recognized as the best option in producing TiAl components with key benefits of accuracy, versatility and integrity. The collapsibility of ceramic moulds for investment casting is critical in the manufacturing process of TiAl components due to TiAl's intrinsic brittleness at room temperature. The aim of the present research is to provide a method for production of TiAl components by investment casting in ZrO₂ ceramic moulds with improved collapsibility. Slurries prepared with high polymer additions were utilized during the preparation of ceramic moulds. The stress/strain curves obtained from green and baked ceramic moulds demonstrate that the green strength was increased with the application of high polymer, while baked strength decreased, thus the collapsibility of ceramic moulds was improved. It is suggested that this result is related to the burn-out of high polymer which left a lot of cavities. The experimental findings were also verified by the investment casting of "I"- shaped TiAl components.