Patent ID: 6821628
Filing Date: 2004-11-23
Classification: C03C,Y10T

Abstract:
A cooking panel consisting of an opaque glass-ceramic material, said opaque glass-ceramic material being uniformly colored throughout and having keatite mixed crystals as the predominant crystalline phase, wherein said cooking panel is made by ceramicizing a transparent colored glass-ceramic material having high quartz mixed crystals as the predominant crystalline phase to form the cooking panel with a color in a color location range in the L*a*b* color system with a brightness parameter value (L*) less than 85 and with a color shade and chromaticity in the L*C*h color system; wherein said color location range of said cooking panel is at least approximately in a color location range of accumulated soiling material and dirt to be expected on said cooking panel for respective service and wear patterns;wherein said transparent glass-ceramic material has the following composition (in percent by weight): SiO2, 62 to 68; Al2O3, 19.5 to 22.5; Li2O, 3.0 to 4.0; Na2O, 0 to 1.0; K2O, 0 to 1.0; BaO, 1.5 to 3.5; CaO, 0 to 1.0; MgO, 0 to 0.5; ZnO, 0.5 to 2.5; TiO2, 1.5 to 5.0; ZrO2, 0 to 3.0; MnO2, 0 to 0.4; Fe2O3, 0 to 0.2; CoO, 0 to 0.30; NiO, 0 to 0.30; V2O5, 0 to 0.80; Cr2O3, 0 to 0.20; F, 0 to 0.20; Sb2O3, 0 to 2.0 and As2O3, 0 to 2.0; wherein a total amount of said Na2O+ said K2O is between 0.5 and 1.5; a total amount of said BaO+ said CaO is between 1.5 and 4.0; a total amount of said TiO2 and said ZrO2 is between 3.5 and 5.5 and a total amount of said Sb2O3 and said As2O3 is 0.5 and 2.5; whereby soiling and wear are less conspicuous.