Abstract: Glass ceramic precursor compositions comprise from about 15 to about 75 percent by weight of titanium diboride and from about 10 to about 85 percent by weight of a silica compound, such as colloidal silica. The glass ceramic precursor compositions may also contain an amount up to about 60 percent by weight of an intemetallic compound, such as silicon carbide. Upon firing of the precursor compositions, glass ceramic materials are formed which are useful at high temperatures and in harsh environments as sealants, as protective coatings or as articles of manufacture.

Abstract: A die material particularly suitable for the making of castings or the like, comprises 50 to 80 parts of magnesium oxide, 10-40 parts of alumina, 2 to 6 parts of monohydrated ammonium phosphate, and 1 to 4 parts of dihydrated ammonium phosphate. The dry blend thus formed, when mixed with a chilled liquid binder containing a collodial silica sol of about 40 weight percent solids content in the ratio of one portion of the liquid binder and from 2 to 5 portions of the dry blend, forms a ceramic slurry which can be readily set in hot water within 4 to 10 minutes. The set ceramic casting is then dry heated to about 250.degree. F. for one to two hours. Molten metal is then applied on the casting for forming a metal jacket to use in dental prostheses.