Aqueous gel casting of water-soluble calcia-based ceramic core for investment casting using epoxy resin as a binder

Abstract

A new water-soluble calcia-based ceramic core of using epoxy resin binder was developed for investment casting by aqueous gel casting. The influences of dispersant addition and solid loading on the rheological property of the slurries were investigated. The low-shrinkage and high-strength ceramic body was obtained by adjusting binder addition and solid loading. The water-soluble behavior of the calcia-based ceramic core and its solution mechanism were studied. The results show that the 48 vol% slurry composing of 6 wt% dispersant content, 16 wt% binder content, and 20 wt% hardener content can prepare a stable and fluidic slurry, and the bending strength of the dried green body is 29.5 ± 1.4 MPa, the linear shrinkage is 3.62 %, and the green relative density is 58.5 % with a homogeneous microstructure. After sintering at 1300 °C, the ceramic core exhibits a uniform microstructure with a bending strength of 25 ± 1.2 MPa, a sintered shrinkage of 11.31 %, a relative density of 92.3 %, and an apparent porosity of 30.5 %. The solubility rate of the ceramic core is 2.83 kg/min m2, and the dissolution of the ceramic core in water is exothermal. The water-soluble calcia-based ceramic core fabricated by aqueous gel casting using epoxy resin could overcome the poor leachability of the common ceramic core and enhanced the production efficiency.