| 摘要 |
PURPOSE:To increase the strength of a frozen mold and prevent crazing by mixing a suitable amount of water and specific binders into molding sand then molding and freezing the same. CONSTITUTION:As binders, those consisting essentially of magnesium compounds, for example, magnesium sulfate, those consisting essentially of calcium compounds, for example, calcium chloride, etc., those consisting essentially of sodium compounds, for example, sodium chloride, etc., those consisting essentially of sodium silica, those consisting essentially of silicic acid anhydride, for example, colloidal silica, etc., those consisting of sugar, for example, grape sugar, etc., those consisting essentially of chemical glues, for example, polyvinyl acetate, etc., and their mixtures are used. These result in increased viscosity of the water mixed with the molding sand, distribution of viscous water in the spaces between sand and sand, increased contact area between sand and water, and increased strength, particularly deflection strength and tensile strength of the frozen mold. |
