| 摘要 |
PURPOSE: To shorten molding time and improve the strength of a molding when extracted from a molding die by pouring and forming a slurry obtained by blending and kneading ceramic powder, silica sol and gypsum in a molding diet and drying and baking the molding from the die after the slurry is cured. CONSTITUTION: Silica sol containing 20% of SiO2 is kneaded with gypsum at a ratio of 30 to 100 pts.wt. and 10 to 100 pts.wt. as a concentration. In addition, 100 pts.wt. of molten quartz averaging about 22μm of pain size are charged and kneaded in the mixture. Then this mixture is poured into a molding die measuring about 100mm in width, about 100mm in length and about 30mm in thickness. In about 3min., the molding is taken out, then is left alone for free drying for about 24 hours, and is dried at low temperature of 110 deg.C for about three hours. After that, the molding is baked. Consequently, no hair cracks are found in the molding and it is used adequately as a sound core for precision casting. Further, the molding has an improved strength after drying and also an enhanced bending strength at three points after baking. |
