Abstract
The strength of ceramic shell is very important for our ceramic process, which does not supported by back sand. We already reported that the most suitable refractory material for the ceramic mold is a 1 : 1 mixture of zircon and fused silica. The purpose of this paper is to present the relationship between the distribution of particle size of ceramic powder and strength of the ceramic shell.
The bending strength increases with the coarse particle size ratio when the ratio is below 80%. The maximum values occur when the particle size ratio, namely COARSE : FINE is 80 : 20. This result suggests that the most preferable mold is made by the ratio, coarse 80% ; fine 20%.
The maximum filling of the particle can be expressed by entropy of the particle size ratio by the equation Vmix ＝ ΣViXi ＋ kΣXi ln Xi In which the apparent volume of suspensions become minimum when the ratio of coarse particle is 80mass%. The thickness of ceramic shell layer increases with the coarse particle size ratio. On this basis, we developed the ceramic mold process without back-up sand to produce various stainless steel castings.
