| 摘要 |
A binder for a foundry mould or core comprises an alkali metal salt of a polyvalent organic acid or a polymerized monovalent organic acid, for example sodium polyacrylate, and an alkaline earth hydroxide such as calcium hydroxide, together with a suitable solvent. Up to 80% of the calcium hydroxide may be replaced by a polyvalent metal oxide or hydroxide. The mixture may include small proportions of other materials, such as aluminum sulphate. It is important that the pH of the organic acid salt solution before mixing with the alkaline earth hydroxide should not be too high and it should preferably be between 5 and 8, in particular between 5.7 and 6.6.
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