Abstract: An oxidation prevention coating for graphite up to at least 1000 degrees Centigrade. Both a non-conductive and a conductive coating are described for use in coating graphite crucibles, graphite electrodes, and the like. All of the compositions utilize a binder/suspension liquid phase in an amount from about 40 to about 55 wt % of the total paintable mixture. This binder/suspension liquid phase is formed by intimately mixing colloidal silica solution, mono-aluminum phosphate solution and ethyl alcohol. The non-conducting embodiment of the invention is produced by mixing finely divided boric acid and silicon carbide with the binder/suspension liquid phase. The preferred conductive coating substitutes a mixed TiC-SiC for the SiC of the non-conductive embodiment. The resultant material is very stable (i.e., does not settle), is paintable upon the graphite, and is easily dried at or near room temperature. A few thin coats, with drying between applications, totaling only about 0.15 to about 0.
Type:
Grant
Filed:
February 2, 1987
Date of Patent:
December 8, 1987
Assignee:
ZYP Coatings, Inc.
Inventors:
Lloyd R. Chapman, Cressie E. Holcombe, Jr.