abstract |
Transparent glass-ceramics comprising the following composition, expressed in terms of weight percent on an oxide basis: 60-75 SiO2, 8-20 Al2O3, 2-10 ZnO, 1-6 MgO, 1-10 TiO2, 0-6 ZrO2, 0-3 BaO, ZnO+MgO in combination being greater then or equal to about 5.5, and TiO2+ZrO2 in combination being greater than about 4. The glass-ceramics have thermal expansion coefficients of about 22-32x10<-7>/DEG C and strain points over 850 DEG C. |