Transparent glass-ceramics of high negative expansion for use as decorative glazes

Claim 1

A transparent glass-ceramic material containing beta-quartz solid solution as the predominant crystal phase especially suitable for application as a decorative glaze to glass, glass-ceramic, and ceramic bodies exhibiting an average coefficient of thermal expansion (0°-300° C.) of less than 15×10 -7 /°C., said glass-ceramic material demonstrating an average coefficient of thermal expansion (25°-100° C.) of less than -15×10 -7 /°C., excellent resistance to attack by acids and bases as evidenced by essentially no change of gloss and a weight loss of no more than about 0.02% after immersion for 24 hours at 96° C. in a aqueous solution containing 10% by weight citric acid and essentially no change of gloss and a weight loss of no more than about 0.02% after immersion for 24 hours at 96° C. in an aqueous solution containing 0.3% by weight of an alkaline detergent, and consisting essentially, expressed in terms of weight percent on the oxide basis, of ______________________________________ SiO.sub.2 50-67 Al.sub.2 O.sub.3 22-32 Li.sub.2 O 4.5-7 TiO.sub.2 and/or ZrO.sub.2 4.5-8 ______________________________________