ABSTRACT
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 789
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 790
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791
Foundry Sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791
Binder System . . . . . . . . . . . . . . . . . . . . . . . . . . . 791
Gore Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 796
Optional Additives . . . . . . . . . . . . . . . . . . . . . . . . . . 798
Application of the Binder . . . . . . . . . . . . . . . . . . 803
Polyvinyl Alcohol or Hydrolyzed
Polyvinyl Acetate . . . . . . . . . . . . . . . . . . . . . . . . 804
Polymer Resin Aqueous Dispersions and
Alcoholic Solutions . . . . . . . . . . . . . . . . . . . . . . 804
Polymer Resin-Zircon or Graphite Mixtures . . . 804
Casting Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . 805
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . 805
Compositions and method for producing foundry sand cores or molds of initial high strength but with
essentially no strength after casting metals above 7008C which involves shaping and setting a composition containing foundry sand and a binder comprising sodium, potassium, or lithium silicate and sufficient amor-
phous silica so that the fraction of the total silica in the binder solution which is present as amorphous silica
is from 2 to 75%, the amorphous silica having a particle size in the range from about 2 to 500 nm and the
binder having a molar ratio of silica to alkali metal oxide ranging from 3.5:1 to 10.1.
