Claims
- 1. Process for preparing a quartz glass cylinder capable of forming an outer layer of uniformly fine crystalline silica when heated to a temperature at which such crystalline silica forms which comprises applying to the outer surface of a quartz glass cylinder a coating consisting essentially of a solution or suspension of a compound containing crystallization promoting nuclei having a rate of diffusion in quartz glass less than that of sodium at elevated temperatures, said nuclei being selected from the group of an element from Group IV of the periodic table, and boron, aluminum, phosphorus, antimony, zinc, magnesium, calcium, gallium, and mixtures thereof, then decomposing said compound and diffusing said nuclei into the outer surface of said cylinder by heating the coated cylinder at temperatures above the fusion temperature of silica without causing recrystallization of said quartz glass cylinder.
- 2. Process of claim 1 wherein only the central portion of the outer surface of said cylinder is coated.
- 3. Process for preparing a quartz glass tube capable of forming an outer layer of uniformly fine crystalline silica when heated to a temperature at which such crystalline silica forms which comprises applying to the outer surface of a quartz glass cylinder a coating consisting essentially of a solution or suspension of a compound containing crystallization promoting nuclei having a rate of diffusion in quartz glass less than that of sodium at elevated temperatures, said nuclei being selected from the group of an element from Group IV of the periodic table, and boron, aluminum, phosphorus, antimony, zinc, magnesium, calcium, gallium and mixtures thereof, then decomposing said compound and diffusing said nuclei into the outer surface of said cylinder by heating the coated cylinder at temperatures above the fusion temperature of silica without causing recrystallization of said quartz glass cylinder, and simultaneously drawing said cylinder into a tube.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2038564 |
Aug 1970 |
DT |
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Parent Case Info
This is a division of application Ser. No. 166,842, filed July 28, 1971 now U.S. Pat. No. 3,772,154.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3464880 |
Rinehart |
Sep 1969 |
|
3773487 |
Plumat et al. |
Nov 1973 |
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3776809 |
Baumler et al. |
Dec 1973 |
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Divisions (1)
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Number |
Date |
Country |
Parent |
166842 |
Jul 1971 |
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