| 配方类型： |
METALS AND THEIR TREATMENT |
| 配方说明： |
Precision-Casting Refractory Mixture |
| 配制方法： |
To function as an investment binder, ethyl silicate is first hydrolyzed. To prepare a completely hydrolyzed ethyl silicate solution, stir 15 volumes of condensed ethyl silicate or tetraethyl orthosilicate into a mixture of 8 volumes of "Synasol" solvent (denatured ethyl alcohol) and 2 volumes of 1% hydrochloric acid. Hydrochloric acid serves as the hydrolysis catalyst. Allow the mixture to stand a minimum of 2 hours before use to insure complete hydrolysis. This solution will contain 17.5% silica by weight or 16 g. of silica per 100 cc. of solution and is called "anhydrous," since it contains just enough water to give complete hydrolysis. It is referred to as Solution 1 in the rest of this article. A similar solution of the same silica content can be made from ethyl silicate 40 by using a mixture of 37.6% of this product with 59.8% "Synasol" solvent and 2.6% of 3% hydrochloric acid.
The anhydrous hydrolyzed ethyl silicate solution is made ready for use by adding more water to give shorter setting times. |
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