Patent ID: 7338714

Claim:
A regionally coated noble metal element for use in glass production, wherein said regionally coated noble metal element has an uncoated region for contacting a glass melt and is provided with an H 2 -impervious layer or an H 2 -impervious and O 2 -impervious layer on a side opposite from the uncoated region for contacting the glass melt; wherein said H 2 -impervious layer or said H 2 -impervious and O 2 -impervious layer has a thickness greater than or equal to 1 mm, is heat-resistant, liquid, or solid, and said H 2 -impervious layer or said H 2 -impervious and O 2 -impervious layer contains at least one glass or glass mixture or a partly or completely crystallized glass or a ceramic material; wherein said H 2 -impervious layer or said H 2 -impervious and O 2 -impervious layer contains at least one glass material and said at least one glass material has a composition, in percent by weight, comprising: SiO 2 40 to 99 Al 2 O 3 1 to 30 B 2 O 3 0 to 30 BaO 0 to 15 CaO 0 to 20 MgO 0 to 8 ZrO 2 0 to 5 ΣR 2 O 0 to 25 P 2 O 5 0 to 10 Cr 2 O 3 0 to 3 TiO 2 0 to 10 Fe 2 O 3 0 to 10 ZnO 0 to 5 MnO 0 to 10 SrO 0 to 10 PbO 0 to 70 Fluorine 0 to 1 wherein ΣR 2 0 denotes a sum total amount of Li 2 O, Na 2 O, K 2 O, and Cs 2 0.