US4244723A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Spontaneously-formed mullite glass-ceramics
Assignee: Corning Glass Works
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Filing: 1975-03-19
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Granted: 1981-01-13
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Expires: 1995-03-19
Abstract
Abstract The present invention is concerned with the fabrication of articles demonstrating the highly-crystalline, fine-grained internal microstructure of conventional glass-ceramic bodies, but which can be formed spontaneously from a molten glass. Thus, the present articles are not produced by heat treating a glass body at elevated temperatures to cause crystallization in situ as is required in the customary manufacture of glass-ceramic articles. More specifically, this invention relates to the fabrication of glass-ceramic articles from compositions within the MgO-Al 2 O 3 -B 2 O 3 -SiO 2 -F field utilizing TiO 2 as a nucleating agent, wherein mullite comprises the principal crystal phase, and which can be formed spontaneously from a molten glass.
Inventors
- 👤 David G. Grossman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:20
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/0036; C03C10/0045
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
163 words
A method for making a highly crystalline glass-ceramic article consisting essentially of mullite and rutile crystals homogeneously dispersed within a glassy matrix, said crystals constituting at least 50% by volume of said article, which comprises the steps of: (a) melting a batch for a glass consisting essentially, by weight on the oxide basis as calculated from the batch, of about 5-15% MgO, 15-35% Al 2 O 3 , 1-5% B 2 O 3 , 30-55% SiO 2 , 8-15% TiO 2 , and 5-15% F; (b) simultaneously cooling said melt to a temperature about 850°-1000° C. and shaping a glass body therefrom at a rate between about 10°-1000° C./minute to obtain phase separation and nucleation therein; (c) further cooling said shaped glass body and exposing said glass body to a temperature between about 650°-850° C. for a sufficient length of time to cause crystallization of the mullite and rutile in said glass body; and then (d) cooling the crystallized body to room temperature.
Claim 2
Independent Claim
163 words
A method for making a highly crystalline glass-ceramic article consisting essentially of mullite and rutile crystals homogeneously dispersed within a glassy matrix, said crystals constituting at least 50% by volume of said article, which comprises the steps of: (a) melting a batch for a glass consisting essentially, by weight on the oxide basis as calculated from the batch, of about 5-15% MgO, 15-35% Al 2 O 3 , 1-5% B 2 O 3 , 30-55% SiO 2 , 8-15% TiO 2 , and 5-15% F; (b) simultaneously cooling said melt to a temperature about 850°-1000° C. and shaping a glass body therefrom at a rate between about 10°-1000° C./minute to obtain phase separation and nucleation therein; (c) further cooling said shaped glass body and exposing said glass body to a temperature between about 650°-850° C. for a sufficient length of time to cause crystallization of the mullite and rutile in said glass body; and then (d) cooling the crystallized body to room temperature.
Claim 3
Dependent Claim
19 words
A method according to claim 1 wherein said time sufficient to cause crystallization is at least about two minutes.
Claim 4
Dependent Claim
34 words
A method according to claim 1 wherein said batch also contains up to 2% As 2 O 5 and/or up to 5% CaO and/or up to 5% Na 2 O and/or K 2 O.
Claim 5
Dependent Claim
44 words
A method according to claim 3 wherein As 2 O 5 , B 2 O 3 , CaO, and Na 2 O are present in the mole ratio of 1As 2 O 5 , 4B 2 O 3 , 3CaO, and 3Na 2 O.
Claim 6
Dependent Claim
49 words
A method according to claim 1 wherein said batch consists essentially, by weight on the oxide basis as calculated from the batch, of about 6-12% MgO, 18-25% Al 2 O 3 , 2-4% B 2 O 3 , 35-50% SiO 2 , 10-12% TiO 2 , and 8-12% F.
Claim 7
Dependent Claim
27 words
A method according to claim 1 wherein said crystallized body is cooled to room temperature by means of a quick chilling technique to thermally temper said body.
References Cited (Backward Citations)
US3741861A
Cited
US3690855A
Cited
US3804608A
Cited
US3726695A
Cited
US3801295A
Cited
US3846101A
Cited
US3985531A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-01-13 | 1984-07-14 | 1985-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-13 | 1988-07-14 | 1989-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-13 | 1992-07-14 | 1993-01-13 | $7700.00 | Window Closed / Lapsed |