| 摘要 |
PURPOSE:To quickly produce a water soluble casting mold having excellent pressure resistance, collapsing property, accuracy and casting surface by subjecting slurry consisting of gypsum, phlogopite, hydrate of MgSO4, refractories and water to pressure molding, then to drying under specific conditions. CONSTITUTION:The slurry is prepd. by adding water to a mixture contg. the gypsum, phlogopite, hydrate of MgSO4, and refractories. The above-mentioned hydrate of MgSO4 is adequately septa hydrate. The mixing ratio of MgSO4 is specified at the ratio higher than the ratio of the gypsum, for example, >=3:7 by weight. Powder mullite flowers, granular silica sand, etc., are used as the refractories. The mixing ratio of the above mentioned phlogopite is preferably about 30-40% of the gypsum. The above-mentioned slurry is poured into a mold and is molded under pressure, by which a molding having the shape of the casting mold is obtd. After the molding is subjected to the primary drying at <=120 deg.C, the molding is dried at >=200 deg.C. The molding is otherwise subjected to the primary drying at <=120 deg.C down to at least 6% water decrease amt. then to secondary drying by microwave. The water soluble casting mold having the dense and high-strength surface layer part is thereby obtd.
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