Masters Theses


"Every foundry is searching for methods and tools to raise product quality and production while lowering cost. In early 1954 published articles on the new carbon dioxide-sodium silicate process of core hardening began to stir the imagination of most of the foundries throughout the United States, This process has probably claimed more space in the foundry journals than any other subject, hailed by some as a cure-all and dismissed by others as unsatisfactory.

The list of advantages of this process was impressive, but anyone associated with the process was confronted with daily problems that had to be solved regardless of the number of advantages. During the past five years many experiments have been conducted regarding the carbon dioxide-sodium silicate process of sand bonding. Many of the problems of the carbon dioxide process have been solved to an extent that it has been possible to apply it to over thirty per cent of present day core production. Problems such as type and quantity of commercial sodium silicate used, proper sand grain size, amount and method of carbon dioxide gas application, relative humidity control, mixing methods, storage method of mix and gassed cores, control of temperature at the time of mixing, gassing, and storage have been solved to varying degrees.

At present, the most predominate limiting factor in the carbon dioxide-sodium silicate process is collapsibility of the core when used at high temperatures. Perhaps this condition should be defined as core removal after pouring of a relatively high melting temperature metal such as copper base alloys and gray iron rather than core collapsibility, but due to the terminology now in common use, collapsibility will be used to indicate core removal or shakeout of core from the castings. With the use of sodium silicate at high temperatures there has been a very limited degree of success probably due to the drying of the sodium silicate to a hydrated form without any decomposition, and a fluxing action occurring. This condition caused severe sintering of the sand mixture producing a high strength bond which causes poor collapsibility

It is the purpose of this thesis to experimentally attack this problem of collapsibility by the addition of various additives to the basic sodium silicate-sand mixture. Specific additives will promote collapsibility by decreasing the high strength of the bond caused by the fluxing action which forms a glassy silicate during the application of the cores at high temperatures. It may be easily concluded that if this high strength bond could be lowered, the carbon dioxide-sodium silicate process of core hardening would have a more universal application to a greater number of cast metals, specifically copper base alloys and gray iron.

The object of this thesis will be to investigate two of the many factors which affect the carbon dioxide process. These two factors are (1) various additions to the carbon dioxide-sodium silicate core sand mix, and (2) temperature within the range of 1250°F to 1800°F which include the foundry pouring temperatures of such metals as aluminum alloys, and copper alloys. These are the two factors which most affect collapsibility.

It is hoped that a more complete evaluation of the collapsibility problem in the carbon dioxide-sodium silicate process can be compiled from the results of this thesis investigation. Also it is the author’s hope, that in addition to the technical information gained, this investigation will promote the interest of the mechanical engineering student toward the metals casting program at the Missouri School of Mines and Metallurgy"--Introduction, pages 1-3.


Wolf, Robert V., 1929-1999

Committee Member(s)

Miles, Aaron J.
Schaefer, Rodney A., 1926-2002
Erkiletian, Dickran Hagop, Jr.
Remington, Charles R., 1924-2013


Mechanical and Aerospace Engineering

Degree Name

M.S. in Mechanical Engineering


Missouri School of Mines and Metallurgy

Publication Date



vi, 44 pages

Note about bibliography

Includes bibliographical references (page 43).


© 1960 Robert G. Liptai, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Carbon dioxide

Thesis Number

T 1247

Print OCLC #


Electronic OCLC #