Coated metal element used for producing glass
The regionally coated noble metal element for use in glass production has an uncoated region for contacting a glass melt and a side opposite from the uncoated region is provided with an H 2 -impervious layer or an H 2 -impervious and O 2 -impervious layer. The H 2 -impervious layer or H 2 -impervious and O 2 -impervious layer has a thickness greater than or equal to 1 mm, is heat-resistant, liquid, or solid. This layer is made from at least one partly or completely crystallized glass or a glass mixture or a ceramic material. Processes for coating the noble metal element are also described. The coated metal elements can be an electrode in a distributor, a channel or melting tank, a pipe for conducting and conditioning glass melts, a shaping tool for producing pipes and rods or a jacketed platinum tube for direct heating of bottom outlets, transport equipment or charging organs, an agitator, a pipe-drawing head, a feeder head, a plunger in gob feeders, drawing tanks and drawing lips for flat glass production and fining chambers.
1. 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.
2. 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
55 to 70
Al 2 O 2
10 to 30
B 2 O 3
0 to 15
BaO
5 to 15
CaO
3 to 15
MgO
0 to 8
SrO
0 to 10
ZrO 2
0 to 2
ΣR 2 O
0 to 5
P 2 O 5
0 to 10
Cr 2 O 3
0 to 1
TiO 2
0 to 1
Fe 2 O 3
0 to 1
ZnO
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 O.
3. 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 0 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
70 to 85
Al 2 O 3
1 to 8
B 2 O 3
5 to 25
BaO
0 to 5
CaO
0 to 3
MgO
0 to 3
ZrO 2
0 to 2
ΣR 2 O
3 to 15
P 2 O 5
0 to 2
Cr 2 O 3
0 to 2
TiO 2
0 to 6
MnO
0 to 6
Fe 2 O 3
0 to 5
ZnO
0 to 2
Fluorine
0 to 0.5
ΣR 2 O denotes a scum total amount of Li 2 O, Na 2 O, K 2 O, and Cs 2 O.
4. 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
65 to 75
Al 2 O 3
2 to 6
B 2 O 3
0 to 3
BaO
0 to 5
CaO
2 to 7
MgO
0 to 5
ZrO 2
0 to 1
ΣR 2 O
10 to 20
P 2 O 5
0 to 5
Cr 2 O 3
0 to 1
TiO 2
0 to 1
Fe 2 O 3
0 to 5
Fluorine
0 to 1
ZnO
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 O.
5. 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
55 to 75
Al 2 O 3
15 to 25
B 2 O 3
0 to 3
BaO
0 to 5
ZnO
0 to 3
MgO
0 to 2
ZrO 2
0 to 3
ΣR 2 O
1 to 7
P 2 O 5
0 to 5
Cr 2 O 3
0 to 1
TiO 2
0 to 5
Fe 2 O 3
0 to 5
wherein ΣR 2 0 denotes a sum total amount of Li 2 O, Na 2 O, K 2 O, and Cs 2 0.
6. 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 0 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 consists of a glass material having a composition that is identical to glass that is melted, transported, conditioned, or processed with the aid of the coated noble metal element.
7. 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 has a viscosity from 10 to 10 6 dPa·s.
8. The regionally coated noble metal element as defined in claim 7 , wherein said viscosity is from 10 2 to 10 6 dPa·s.
9. 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 comprises said ceramic material and a crushed glass having a particle size of less than 10 mm.
10. The regionally coated noble metal element as defined in claim 9 , wherein said particle size is less than 1 mm.