Heat curable foundry binder systems
AssigneeAshland Inc.
InventorsHelena J. Twardowska, Heimo J. Langer
Life of this patent
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Abstract
This invention relates to heat curable foundry binder systems comprising as separate components (a) a caustic solution of an alkali silicate and (b) hydrated aluminum silicate. The solution is mixed with sand to form a foundry mix. The resulting foundry mix is shaped and heated at an elevated temperature to form a cured foundry shape. Heat is applied by warm air, baking in an oven, microwave, or preferably from hot-box equipment.
Claims12
A heat-curable foundry mix comprising a major amount of an aggregate and the balance a binder solution formed from a mixture of (a) about 60-85 weight percent of a caustic solution of an alkali silicate and (b) about 15 to about 40 weight percent of a hydrated aluminum silicate, said weight percents being based upon the total weight of the binder solution.
A process for preparing a workable foundry shape comprising:
- (a) forming a foundry mix by mixing a foundry aggregate with a bonding amount of up to about 10 percent by weight, based upon the weight of the aggregate, of a binder system comprising:
- (1) caustic solution of sodium silicate, and
- (2) hydrated aluminum silicate, such that the weight percent of (1) in the binder ranges from about 60 to about 85 weight percent and the weight percent of (2) is from about 15 to about 40 weight percent, said weight percents being based upon the total weight of the binder,
- (b) shaping the foundry mix of (a) into a foundry shape;
- (c) contacting the foundry shape of (b) with a source of heat at a temperature of 200.degree. C. to 300.degree. C.;
- and
- (d) allowing the foundry shape to harden into a workable foundry shape.
The process of claim 12 wherein the molar ratio of Na.sub.2 O:Al.sub.2 O.sub.3 in the binder is from 0.7:1.0 to 1.5:1.0, the molar ratio of Na.sub.2 O:SiO.sub.2 in the binder is from 0.2:1.0 to 0.3:1.0, and the molar ratio of SiO.sub.2 :Al.sub.2 O.sub.3 in the binder is from 3.5:1.0 to 5.8:1.0.
Dependencies are inferred from the claim text.