Method of processing ``BPS`` glass ceramic and seals made therewith
A glass ceramic composition, a glass ceramic-to-metal seal, and more specifically a hermetic glass ceramic-to-metal seal prepared by subjecting a glass composition comprising, by weight percent, SiO{sub 2} (65--80%), LiO{sub 2} (8--16%), Al{sub 2}O{sub 3} (2--8%), K{sub 2}O (1--8%), P{sub 2}O{sub 5} (1--5%), B{sub 2}O{sub 3} (0.5--7%), and ZnO (0--5%) to the following processing steps: (1) heating the glass composition in a belt furnace to a temperature sufficient to melt the glass and crystallize lithium phosphate, (2) holding at a temperature and for a time sufficient to create cristobalite nuclei, (3) cooling at a controlled rate and to a temperature to cause crystallization of lithium silicates and growth of cristobalite, and (4) still further cooling in stages to ambient temperature. This process produces a glass ceramic whose high coefficient of thermal expansion (up to 200{times}10{sup {minus}7} in/in/C) permits the fabrication of glass ceramic-to-metal seals, and particularly hermetic glass ceramic seals to nickel-based and stainless steel alloys and copper. 5 figs.
- Research Organization:
- AT&T
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DP00789
- Assignee:
- Sandia Corp., Albuquerque, NM (United States)
- Patent Number(s):
- US 5,820,989/A/
- Application Number:
- PAN: 8-706,852
- OSTI ID:
- 675866
- Resource Relation:
- Other Information: PBD: 13 Oct 1998
- Country of Publication:
- United States
- Language:
- English
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