In the pressure casting of ceramics, the casting speed varies according to the mean diameter, the size distribution and the shape of particle. It is therefore possible to estimate the casting speed from these parameters. In the case where both the size distributions and the shape of the particles are nearly equal, a greater mean particle diameter increases the casting speed. With particles in which the shape is similar and the mean diameters are nearly equal, as the size distribution becomes narrow, the casting speed increases. In the particle systems in which both the size distribution and the mean diameter are nearly equal, a larger particle aspect ratio increases the casting speed. The difference of the casting speed due to the difference of the mean diameter is caused by the difference of the specific surface area of the green body. The difference in casting speed due to the size distribution and the shape is greatly influenced by the packing fraction of the green body. If fine particles are mixed into a coarse fraction at about 40 vol percent fines, the viscosity of the slurry arrives at a minimum and the packing fraction of the green body is at a maximum. Consequently, compared with only the single size particles, the mean particle diameter range of a moldable slurry is expanded and it is possible to mold with lower water content slurries.
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