Relationship between network structure and fracture strength of ceramic core in a gel-casting process

A gel-casting process was employed to prepare a ceramic core with reasonable formability, independent of the composition ratio and process parameters, because the green strength of a ceramic core prepared via the conventional process for precision casting was significantly affected by the starting powder used, the composition ratio, and the process parameters. The shape of the ceramic core was fixed by the network structure, which is significantly influenced by the degree of polymerization and the polymerization rate, generated by polymerization of a prepolymer, such as a monomer combined with a dimer; these factors have a direct relationship on the green strength of the ceramic core. Therefore, the amounts of prepolymer and initiator were controlled to investigate the relationship between the network structure of the polymer and the strength of the ceramic core. The following formulation was found to be suitable for preparing a ceramic core with high formability and a useful network structure: 3.3 wt% monomer, 0.7 wt% dimer, and 0.015 wt% initiator.