Thermally crystallizable glass of the system sio deep 2 - al deep 2 o deep 3 - na deep 2 o - tio deep 2 and, on the basis of this glass ceramic article produced

摘要

Thermally crystallisable glass and glass ceramics. This contains in wt. %: 44-52 SiO2, 22-29 Al2O3, 15-22 Na2O, and 6-12 TiO2 as components essential for thermal crystallisation and, opt. 0-3 K2O. SiO2 + Al2O3 = 69-76, Na2O + K2O = 17-22. The proportion by wt. of SiO2: (Na2O + K2O) is 2.1-3, the molecular ratio of Na2O + K2O): Al2O3 is at least 1.02. The glass also contains one or more components selected from (a) 0-1.7 mole % based on the total moles of SiO2 + Al2O3 + Na2O + K2O): Al2O3 is at least 1.02. The glass also contains one or more components selected from (a) 0-1.7 mole % based on the total moles of SiO2 + Al2O3 + Na2O + K2O of at least one of FeO, ZnO, MgO, CdO, MnO, CoO or NiO and (b) 0-0.06 mole % Cr2O3 and (c) BaO. In the presence of less than 27 wt. % Al2O3, the BaO content is 0-2 wt. %. It is 0-05 wt. % in the presence of more than 27 wt. % Al2O3.