Thermal Stability of Bentonites in Foundry Molding Sand*

George J. Vingas and Arthur H. Zrimsek
Magnet Cove Barium Corporation, Arlington Heights, Illinois
* The writers thank Magnet Barium Corporation for permission to conduct these experiments and publish the results.
P.O. Box 355, Arlington Heights, Illinois.

Abstract: The effects of heat on the behavior of sodium and calcium bentonite in bonding foundry sands were studied.

Tests such as differential thermal analysis, viscosity, and melting or vitrification temperatures do not indicate the suitability of a bentonite for foundry use.

The deterioration temperatures of sodium and calcium bentonite are 1180° and 600°F respectively.

Reactivities of bentonites with cereal as affected by temperature and mulling were also studied. Flowability of sands, defined as mold densification in this paper, is better with heated calcium than sodium bentonite.

Heating bentonites alone does not simulate the conditions encountered in heating bentonite-sand mixtures in a mold.

Clays and Clay Minerals; 1964 v. 13; no. 1; p. 367-380; DOI: 10.1346/CCMN.1964.0130134
© 1964, The Clay Minerals Society
Clay Minerals Society (www.clays.org)