High expansion glass-ceramic articles
Abstract
Abstract The present invention relates to the production of photothermally crystallizable, chemically-machinable glass-ceramic articles exhibiting coefficients of thermal expansion over the temperature interval of 20°-400° C. between 120-160×10 -7 /° C. Base glass articles having compositions consisting essentially, in weight percent, of 5.5-15% Li 2 O, 2-25% Al 2 O 3 , the weight ratio Al 2 O 3 :Li 2 O being less than 1.7:1, 60-85% SiO 2 , and at least one photosensitive metal in the indicated proportion selected from the group of 0.001-0.03% gold, computed as Au, 0.001-0.3% silver, computed as AgCl, and 0.001-1% copper, computed as Cu 2 O, are first exposed to ultraviolet radiations to develop a latent image therein, then heated to a temperature between the annealing and softening points thereof to generate metallic nuclei therein and the growth of lithium metasilicate particles thereon, and, finally, heated to a temperature in excess of 700° C., but less than 800° C., to effect an essentially crystalline article, including the conversion of a portion of the lithium metasilicate crystals to lithium disilicate. Quartz and/or cristobalite will also be formed.
Inventors
- 👤 Patrick McAlinn
Bibliographic Details
Claims Analysis
Total Claims: 3References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1987-10-30 | 1988-04-30 | 1988-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-30 | 1992-04-30 | 1992-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-30 | 1996-04-30 | 1996-10-30 | $7700.00 | Window Closed / Lapsed |