COMPOSITION OF LEAD AND CADMIUM EXEMPTED GLASS FOR GLASS, ENAMELING AND DECORATION OF GLASSES OR VITROCERAMICS, AND PROCESS FOR THE PRODUCTION OF A VITROCERAMIC COVERED WITH IT.

摘要

A borosilicate glass free of lead and cadmium, for coating, glazing and glass or glass ceramic decoration especially for cooking surfaces, has a specific composition and a low thermal expansion coefficient. A lead-cadmium-free borosilicate glass that has a specific composition and a low thermal expansion coefficient is new. A glass with low coefficient of thermal expansion free of lead and cadmium, for coating, glazing and glass or glass ceramic decoration, has the composition (by weight) 0-6% Li {sub, 2} O, 0-5% Na { sub, 2} O, 0 to less than 2% K {sub, 2} O, 2-12% Li {sub, 2} O + Na {sub, 2} O + K {sub, 2} O, 0- 4% MgO, 0-4% CaO, 0-4% SrO, 0-1% BaO, 0-4% ZnO, 3 to less than 10% Al {sub, 2} O {sub, 3}, 13-23 % B {sub, 2} O {sub, 3}, 50-65% SiO {sub, 2}, 0-4% TiO {sub, 2}, 0-4% ZrO {sub, 2}, 0-4 % F (replacing oxygen) and up to 30% of a pigment resistant to cooking temperature. An independent claim is also included for processes for producing a ceramic hob that is coated, enameled and decorated with the previous glass.