Patent ID: 6706653
Filing Date: 2004-03-16
Classification: C03C

Abstract:
A glass-ceramicwhich is opaque, which has a low, or zero thermal expansion coefficient, which contains a solid solution of &bgr;-quartz as crystalline phase, which composition essentially consists, by weight percent, of: 65 to 72% of SiO2 16 to 24% of Al2O3 2 to less than 3% of Li2O 0 to 1% of MgO 3 to 5% of ZnO 0 to 1.5% of BaO 2 to 4.5% of TiO2 and/or ZrO2, with the Al3O3/(TiO2+ZrO2) ratio >5, 0 to an effective and non excessive amount of a least one fining agent, and less than 1% of K2O and/or Na2O.