US5017519A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transparent and nonexpansive glass-ceramic
Assignee: Central Glass Co Ltd
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Filing: 1990-04-23
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Granted: 1991-05-21
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Expires: 2010-04-23
Abstract
Abstract A transparent and colorless glass-ceramic containing crystals of β-quartz and β-eucryptite is obtained by heat-treating a glass essentially composed of 63-69 wt % of SiO 2 , 18-22 wt % of Al 2 O 3 , 3-5 wt % of Li 2 O, 1-3 wt % of MgO, 4-6 wt % of ZrO 2 , 0-2 wt % of ZnO, 0-2 wt % of P 2 O 5 , 0-2 wt % of Na 2 O, 0-2 wt % of BaO and 0.3-1 wt % of As 2 O 3 , with proviso that the proportion of ZrO 2 to SiO 2 is not lower than a specified level and that the molar ratio of Al 2 O 3 to the total of Li 2 O, MgO and ZnO is within a specified range. The thermal expansion coefficient of this glass-ceramic is very close to zero over the range from room temperature to about 300° C.
Inventors
- 👤 Shigeki Morimoto
- 👤 Kenji Sugiura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 16:48
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/0036; C03C10/0045
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
189 words
A transparent and low expansion glass-ceramic, which comprises fine crystals of β-quartz and β-eucryptite crystallized from a glass and dispersed in a glass matrix provided by the uncrystallized part of the glass, the glass consisting essentially of, expressed as oxides, 63-69 wt % of SiO 2 , 18-22 wt % of Al 2 O 3 , 3-5 wt % of Li 2 O, 1-3 wt % of MgO, 4-6 wt % of ZrO 2 , 0-2 wt % of ZnO, 0-2 wt % of P 2 O 5 , 0-2 wt % of Na 2 O, 0-2 wt % of BaO, and 0.3-1 wt % of As 2 O 3 , with the proviso that the inequalities (I) and (II) are both satisfied: log Z≧8.8-4.47 log S (I) where Z is the content (wt %) of ZrO 2 in the glass, and S is the content (wt %) of SiO 2 in the glass, 0.9≦a/(p+q+r)≦1.1 (II) where a is the molar fraction of Al 2 O 3 in the glass, and p, q and r are molar fractions of Li 2 O, MgO and ZnO in the glass, respectively.
Claim 2
Dependent Claim
189 words
A transparent and low expansion glass-ceramic, which comprises fine crystals of β-quartz and β-eucryptite crystallized from a glass and dispersed in a glass matrix provided by the uncrystallized part of the glass, the glass consisting essentially of, expressed as oxides, 63-69 wt % of SiO 2 , 18-22 wt % of Al 2 O 3 , 3-5 wt % of Li 2 O, 1-3 wt % of MgO, 4-6 wt % of ZrO 2 , 0-2 wt % of ZnO, 0-2 wt % of P 2 O 5 , 0-2 wt % of Na 2 O, 0-2 wt % of BaO, and 0.3-1 wt % of As 2 O 3 , with the proviso that the inequalities (I) and (II) are both satisfied: log Z≧8.8-4.47 log S (I) where Z is the content (wt %) of ZrO 2 in the glass, and S is the content (wt %) of SiO 2 in the glass, 0.9≦a/(p+q+r)≦1.1 (II) where a is the molar fraction of Al 2 O 3 in the glass, and p, q and r are molar fractions of Li 2 O, MgO and ZnO in the glass, respectively.
Claim 3
Dependent Claim
21 words
A glass-ceramic according to claim 1, wherein the content of ZnO in the glass is not less than 0.5 wt %.
Claim 4
Dependent Claim
21 words
A glass-ceramic according to claim 1, wherein the content of BaO in the glass is not less than 0.5 wt %.
Claim 5
Dependent Claim
33 words
A glass-ceramic according to claim 1, having a thermal expansion coefficient in the range from -5×10 -7 /°C. to 5×10 -7 /°C. over the range of temperature from room temperature to 300° C.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-05-20 | 1994-11-19 | 1995-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-05-20 | 1998-11-19 | 1999-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-05-20 | 2002-11-19 | 2003-05-21 | $7700.00 | Window Closed / Lapsed |