| 摘要 |
The binder for sand moulds and cores with improved knock out properties consists of an aq. soln. contg. alkaline metal silicate 26-45, carbohydrate 3-27, and phenolic compd. 0.5-1.5 wt%. Optionally an oxyanion capable of forming a water soln. complex with the carbohydrate is added. Thus, 6.15 parts Na2B4O7 was dissolved in 100 wt. parts syrup contg. 71 % hydrogenated starch hydrolyzate with a dextrose equiv. of <=0.2. Then, 20 parts of the soln. were mixed with 80 wt. parts soln. contg. 44 wt.% Na silicate with a SiO2:Na2O ratio of 2.2:1. Then, 3.5 parts binder soln. was mixed with CO2.
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