US3907577A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Making surface crystallized glass bodies and resulting product
Assignee: Schott AG
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Filing: 1973-12-21
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Granted: 1975-09-23
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Expires: 1993-12-21
Abstract
Abstract A process for the production of a high-strength translucent or opaque glass body which is resistant to temperature change and which has a partially crystalline surface layer and the product produced thereby. The glass comprises a Beta -spodumene and/or h-quartz solid solutions and a residual glass phase, and which differs in its oxidic composition from the basic glass by a higher Li2O content and correspondingly lower content of the other alkali oxides, the total mol content of the alkali oxides being however substantially the same. In the process, a heat treatment for the controlled surface crystallization is carried out on the glass, during which an ion exchange occurs within the glass between Li ions in the interior of the glass and Na-and/or K-ions on that side of the growing crystal front which is facing the interior of the glass.
Inventors
- 👤 Dr Werner Kiefer
- 👤 Dr Werner Sack
- 👤 Dr Dieter Krause
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:16
CPC Classifications
C; C03; C03C; C03C21/00; C03C10/00; C03C10/0018; C03C10/0027; C03C21/008; C03C2218/00; C03C2218/30; C03C2218/345
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
26 words
The process of claim 1 wherein said glass additionally contains from about 0.5 to 1 weight percent As2O3 on a 100 weight percent total composition basis.
Claim 2
Dependent Claim
22 words
The process of claim 1 wherein said glass additionally contains up to about 10 weight percent of at least one coloring oxide.
Claim 3
Dependent Claim
33 words
The process of claim 1 whErein said heating is conducted using temperatures in the range from said transition temperature of said glass up to the upper devitrification limiting temperature above said transition temperature.
Claim 4
Dependent Claim
58 words
The process of claim 4 wherein said glass body is drawn upwardly through a vertically disposed gradient furnace wherein the upper temperature lies in the region of said upper devitrification limiting temperature and the speed of transit of said body in said furnace is such as to produce in said body a surface crystallization thickness of predetermined value.
Claim 5
Dependent Claim
33 words
The process of claim 1 wherein said heating is concluded using temperatures in the range from about said transition temperature of said glass up to a temperature about 300*C above said transition temperature.
Claim 6
Dependent Claim
61 words
The process of claim 6 wherein the heating of the glass body is performed quickly from said transition temperature to a crystallization temperature at which said crystals have a growth speed of about 100 microns per hour, and said glass body is kept at said crystallization temperature for a time sufficient to produce a closed crystalline surface layer on said body.
Claim 7
Dependent Claim
103 words
The process of claim 6 wherein the heating of the glass body is performed at a temperature from said transition temperature to 50* to 100*C above said transition temperature and said glass body is kept at said temperature for a time sufficient to produce a closed crystalline surface layer of a few microns on said body and the temperature then raised to a crystallization temperature at which said crystals have a growth speed of about 100 microns per hour, and said glass body is kept at said crystallization temperature for a time sufficient to produce a closed crystalline surface layer on said body.
Claim 8
Dependent Claim
34 words
The process of claim 1 wherein said glass is initially clear and transparent and also has a P2O5 content of less than about 2 weight percent on a 100 weight percent total composition basis.
Claim 9
Dependent Claim
45 words
The process of claim 1 wherein said glass is initially clear and transparent and also has a CaO content of less than about 1 weight percent and a BaO content of less than about 5 weight percent on a 100 weight percent total composition basis.
Claim 10
Dependent Claim
34 words
The process of claim 1 wherein said glass is initially clear and transparent and also has an Al2O3 content of more than about 20 weight percent on a 100 weight percent total composition basis.
Claim 11
Dependent Claim
17 words
The process of claim 1 wherein said glass comprises on a 100 weight percent total composition basis:
Claim 12
Dependent Claim
22 words
The process of claim 1 wherein said body before said heating is coated with a thin dry coating of lithium containing substance.
Claim 13
Dependent Claim
29 words
The process of claim 13 wherein said lithium containiNg substance comprises a member of the group consisting of lithium aluminate, lithium sulphate, lithium titanate, lithium zirconate, or lithium silicate.
Claim 14
Dependent Claim
13 words
The process of claim 14 wherein said lithium containing substance comprises lithium aluminate.
Claim 15
Dependent Claim
30 words
The process of claim 13 wherein after being so coated with said lithium containing substance said body is first heated to between about 100 to 150*C to dry such coating.
Claim 16
Dependent Claim
113 words
A GLASS BODY HAVING AT LEAST APARTIALLY CRYSTALLINE SURFACE LAYER OF CRYSTALS SELECTED FROM THE GROUP CONSISTING OF B-SPODUME, H-QUARTZ AND MIXTURES THEREOF, SAID CRYSTALS HAVING INCORPORATED THEREWITH A HIGHER WEIGHT PERCENTAGE OF LITHIUM AND A LOWER PERCENTAGE OF OTHER ALKALI METAL OXIDE ON A 100 WEIGHT PERCENT TOTAL COMPOSITION BASIS THAN WAS INITIALLY PRESENT IN THE GLASS COMPRISING SAID BODY, AT LEAST A PORTION OF SUCH ADDITIONAL QUANTITY OF SUCH LITHIUM IN SAID CRYSTALS HAVING BEEN OBTAINED BY INTERNAL LITHIUM ION EXCHANGE OF IONS SELECETED FROM THE GROUP CONSISTING OF SODIUM AND POTASSIUM FROM INTERIOR PORTIONS OF SAID GLASS BODY, SAID GLASS COMPRISING INITIALLY ON A 100 WEIGHT PERCENT OTAL CMPSOSITION BASIS:
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) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |