| 摘要 |
PURPOSE:To obtain a frozen mold of improve strength, particularly, transverse strength and tensile strength by mixing a proper amount of water and a surfactant with molding sand. CONSTITUTION:The surfactant may be any of four kinds; cationic, anionic, amphoteric and nonionic, but it is desirably a surfactant of less foaming characteristic and high penetrating power and does not contain any ion component in its components The addition of this surfactant lowers the surface tension of water, improves uneven wetting of sand and water, increases contact area of sand and water, enhances packing density of the mold and increases strength thereof. The mixing ratio of the molding sand, water and the surfactant is, for example, 100:10:0.002 or 100:3.5:0.002 by weight. |
