US Patent 7846858 Glaze for annealing surfaces

The invention concerns a glaze for annealing surfaces, particularly of ceramic parts used in the field of medicine, comprising the components 30 to 55% SiO2, 0 to 7% Al2O3, 10 to 30% R2O, 5 to 10% R′O, 0.5 to 15% B2O3, 5 to 10% Bi2O3, 1 to 10% P2O5, 0 to 5% Sb2O3, 0 to 5% SnO2, 0 to 5% TiO2 and 5 to 10% ZrO2 by mass, wherein (R) is one or several alkali metals and (R′) is one or several bivalent metals from the group comprising alkaline earth metals and zinc, and wherein the glaze is obtained by melting or sintering the components.