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US3957496A
Expired / Lapsed
US
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Molybdenum sealing glass-ceramic composition
Assignee: Energy Research and Development Administration ERDA
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Filing: 1975-09-23
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Granted: 1976-05-18
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Expires: 1995-09-23
Abstract
Abstract The invention relates to a glass-ceramic composition having low hydrogen and helium permeability properties, along with high fracture strength, a thermal coefficient of expansion similar to that of molybdenum, and adaptable for hermetically sealing to molybdenum at temperatures of between about 900° and about 950°C. to form a hermatically sealed insulator body.
Inventors
- 👤 Robert J. Eagan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 10:22
CPC Classifications
C; C03; C03C; C03C27/00; C03C27/02; C03C10/00; C03C10/0036; C03C10/0045; C03C8/00; C03C8/24
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
126 words
A glass-ceramic of low helium permeability and high modulus of rupture, of composition consisting essentially of from about 38 to about 42 weight percent silicon dioxide, from about 8 to about 10 weight percent aluminum oxide, from about 2 to about 4 weight percent calcium oxide, from about 2 to about 4 weight percent magnesium oxide, from about 4 to about 6 weight percent barium oxide, from about 30 to about 35 weight percent zinc oxide, from about 2.0 to about 2.8 weight percent sodium oxide, from about 0.2 to about 0.4 weight percent cobalt oxide, from about 0.5 to about 2.0 weight percent titanium dioxide, and from about 2.5 to about 3.5 of at least one of the oxides of phosphorous pentoxide and zirconium oxide.
Claim 2
Dependent Claim
126 words
A glass-ceramic of low helium permeability and high modulus of rupture, of composition consisting essentially of from about 38 to about 42 weight percent silicon dioxide, from about 8 to about 10 weight percent aluminum oxide, from about 2 to about 4 weight percent calcium oxide, from about 2 to about 4 weight percent magnesium oxide, from about 4 to about 6 weight percent barium oxide, from about 30 to about 35 weight percent zinc oxide, from about 2.0 to about 2.8 weight percent sodium oxide, from about 0.2 to about 0.4 weight percent cobalt oxide, from about 0.5 to about 2.0 weight percent titanium dioxide, and from about 2.5 to about 3.5 of at least one of the oxides of phosphorous pentoxide and zirconium oxide.
Claim 3
Dependent Claim
63 words
The glass-ceramic of claim 1 for sealing to molybdenum, having a low helium permeability value of about 2.5 × 10 - 10 cubic centimeters (standard temperature and pressure) seconds - 1 centimeters - 1 atmospheres - 1 and a modulus of rupture of equal to or greater than about 11 thousand pounds per square inch, and sealing at a temperature of about 925°C.
Claim 4
Dependent Claim
87 words
The glass-ceramic of claim 1 wherein said silicon dioxide is about 40.0 weight percent, said phosphorous pentoxide is about 3.0 weight percent, said aluminum oxide is about 9.0 weight percent, said calcium oxide is about 3.0 weight percent, said magnesium oxide is about 3.0 weight percent, said barium oxide is about 5.2 weight percent, said zinc oxide is about 33.0 weight percent, said sodium oxide is about 2.6 weight percent, said cobalt oxide is about 0.2 weight percent, and said titanium dioxide is about 1.0 weight percent.
Claim 5
Dependent Claim
87 words
The glass-ceramic of claim 1 wherein said silicon dioxide is about 40.6 weight percent, said zirconium oxide is about 3.0 weight percent, said aluminum oxide is about 9.0 weight percent, said calcium oxide is about 3.0 weight percent, said magnesium oxide is about 3.0 weight percent, said barium oxide is about 5.2 weight percent, said zinc oxide is about 33 weight percent, said sodium oxide is about 2.0 weight percent, said cobalt oxide is about 0.2 weight percent, and said titanium dioxide is about 1.0 weight percent.
Claim 6
Independent Claim
305 words
A method of making a glass-ceramic for tubes comprising intermixing from about 38 to about 42 weight percent silicon dioxide, from about 8 to about 10 weight percent aluminum oxide, from about 2 to about 4 weight percent calcium oxide, from about 2 to about 4 weight percent magnesium oxide, from about 4 to about 6 weight percent barium oxide, from about 30 to about 35 weight percent zinc oxide, from about 2.4 to about 2.8 weight percent sodium oxide, from about 0.2 to about 0.4 weight percent cobalt oxide, from about 0.5 to about 2 weight percent titanium dioxide, and from about 2.5 to about 3.5 weight percent of at least one of the oxides of phosphorous pentoxide and zirconium oxide, heating said intermixture to from about 1500° to about 1600°C. to melting, maintaining said melt for from about 12 to about 24 hours, cooling said melt to a temperature of from about 625° to about 650°C. and maintaining at this temperature for about 5 minutes, thereafter cooling to ambient temperature at a cooling rate of from about 2° to about 5°C. per minute to cool and anneal said melt and form an initial glass composition preform, disposing said preform adjacent a molybdenum surface, thereafter heating said molybdenum surface and said preform to a temperature of from about 900° to about 950°C. to melt said glass composition, applying a pressure of from about 1 pound per square inch to about 2 pounds per square inch to said glass composition while being so heated to flow said glass composition into contact with said molybdenum surface, holding said temperature and pressure for from about 15 minutes to about 60 minutes, cooling said glass to form a glass-ceramic composition, and thereafter cooling said glass-ceramic composition to ambient temperature providing a glass-ceramic hermetically sealed to said molybdenum surface.
Claim 7
Independent Claim
305 words
A method of making a glass-ceramic for tubes comprising intermixing from about 38 to about 42 weight percent silicon dioxide, from about 8 to about 10 weight percent aluminum oxide, from about 2 to about 4 weight percent calcium oxide, from about 2 to about 4 weight percent magnesium oxide, from about 4 to about 6 weight percent barium oxide, from about 30 to about 35 weight percent zinc oxide, from about 2.4 to about 2.8 weight percent sodium oxide, from about 0.2 to about 0.4 weight percent cobalt oxide, from about 0.5 to about 2 weight percent titanium dioxide, and from about 2.5 to about 3.5 weight percent of at least one of the oxides of phosphorous pentoxide and zirconium oxide, heating said intermixture to from about 1500° to about 1600°C. to melting, maintaining said melt for from about 12 to about 24 hours, cooling said melt to a temperature of from about 625° to about 650°C. and maintaining at this temperature for about 5 minutes, thereafter cooling to ambient temperature at a cooling rate of from about 2° to about 5°C. per minute to cool and anneal said melt and form an initial glass composition preform, disposing said preform adjacent a molybdenum surface, thereafter heating said molybdenum surface and said preform to a temperature of from about 900° to about 950°C. to melt said glass composition, applying a pressure of from about 1 pound per square inch to about 2 pounds per square inch to said glass composition while being so heated to flow said glass composition into contact with said molybdenum surface, holding said temperature and pressure for from about 15 minutes to about 60 minutes, cooling said glass to form a glass-ceramic composition, and thereafter cooling said glass-ceramic composition to ambient temperature providing a glass-ceramic hermetically sealed to said molybdenum surface.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-05-18 | 1979-11-17 | 1980-05-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-18 | 1983-11-17 | 1984-05-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-18 | 1987-11-17 | 1988-05-18 | $7700.00 | Window Closed / Lapsed |