抄録
In order to achieve high-strength ceramic shell mold, the production of suitable ceramic shell is very important. We have already discussed that the most suitable refractory materials were 1 : 1 mixture of zircon and fused silica particles. The aim of this paper is to make clear the relationship between the particle size distribution of refractory materials and the apparent viscosity of slurry on ceramic shell mold.
Two kinds of refractory materials, fused silica particles and zircon particles, were used for the slurry, and colloidal silica was used for the binder. #100 and #350 of the particle size of each refractory material were tested. The six different particle size distributions were set. Three concentration levels of slurry were prepared by changing the fraction of filler and binder.
When the weight fraction of the coarse particles was less than 0.6, the apparent viscosity of the slurry decreased with increasing the weight fraction of coarse particles. The minimum apparent viscosity was obtained at the weight fraction of coarse particles was between 0.6 and 0.8. The apparent viscosity of the slurry good agreed with the semi-theoretical equation ηs ＝ η0 {1 ＋ 3 / (ΦV－1 － ΦVC－1)}, where ηs : apparent viscosity of slurry, η0 : viscosity of colloidal silica binder. ΦV : volume fraction of refractory materials ΦVC : maximum volume fraction of refractory materials obtained from the experiment.
