Hydrogen-supported fluorination of soot bodies

Patent metadata

Field	Value
Publication number	US-9416044-B2
Application number	US-201314431525-A
Country	US
Kind code	B2
Filing date	Sep 6, 2013
Priority date	Sep 27, 2012
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

The invention relates to a method for fluorinating a soot body. The method involves: a) providing a soot body, and b) treating the soot body with a gas mixture containing hydrogen and CnF2n+2 (n=1 or 2) at a temperature in the range of (1,280-n*250)° C. to (1,220-n*100)° C.

First claim

We claim:

1. A method for fluorinating a soot body, comprising the steps of
a) providing a soot body, and
b) treating the soot body with a gas mixture comprising hydrogen and C n F 2n+2 , wherein n=1 or 2, at a fluorination temperature in a range of (1,280-n*250)° C. to (1,220-n*100)° C., wherein the gas mixture contains 35 to 95 vol. % nitrogen based on a total volume of the gas mixture at 25° C.

2. The method according to claim 1 , comprising treating the soot body with a gas mixture comprising CF 4 and hydrogen at a temperature range of 1,050 to 1,120° C.

3. The method according to claim 1 , comprising treating the soot body with a gas mixture comprising C 2 F 6 and hydrogen at a temperature range of 750 to 1,000° C.

4. The method according to claim 1 , wherein the gas mixture contains up to 65 vol. % C n F 2n+2 and hydrogen, each based on a total volume of the gas mixture at 25° C.

5. The method according to claim 1 , wherein the gas mixture contains 10 to 60 vol. % C 2 F 6 or CF 4 , each based on a total volume of the gas mixture at 25° C.

6. The method according to claim 1 , wherein the soot body is a porous SiO 2 soot body having a mean density of 0.48 g/cm 3 to 0.77 g/cm 3 and a specific surface area of more than 5 m 2 /g.

7. A fluorinated soot body obtained by the method according to claim 1 .

8. A method for producing a synthetic glass for an optical element comprising the steps of:
i) producing or providing a soot body;
ii) fluorinating the soot body according to claim 1 ;
iii) optionally chlorinating the fluorinated soot body; and
iv) vitrifying the fluorinated soot body at a pressure of less than 0.1 bar at a temperature above the fluorination temperature.

9. The method according to claim 8 , wherein the soot body is produced by depositing SiO 2 particles for mass deposition on a substrate that rotates about its longitudinal axis using at least one depositing burner.

10. The method according to claim 8 , wherein the synthetic glass is a glass tube.

11. A glass obtained by the method according to claim 8 .

12. An optical element produced by the method according to claim 8 .

13. A method of producing an optical fiber from the glass according to claim 11 , comprising elongating the glass while forming a substrate tube and coating the glass on an internal wall of the substrate tube.

14. A method for fluorinating a soot body, comprising the steps of
a) providing a soot body, and
b) treating the soot body with a gas mixture comprising hydrogen and C n F 2n+2 , wherein n=1 or 2, at a fluorination temperature in a range of (1,280-n*250)° C. to (1,220-n*100)° C., wherein the gas mixture contains hydrogen in an amount of up to 15 vol. % based on a total volume of the gas mixture at 25° C.

15. The method according to claim 14 , comprising treating the soot body with a gas mixture comprising CF 4 and hydrogen at a temperature range of 1,050 to 1,120° C.

16. The method according to claim 14 , comprising treating the soot body with a gas mixture comprising C 2 F 6 and hydrogen at a temperature range of 750 to 1,000° C.

17. The method according to claim 14 , wherein the gas mixture contains up to 65 vol. % C n F 2n+2 and hydrogen, each based on a total volume of the gas mixture at 25° C.

18. The method according to claim 14 , wherein the gas mixture contains 10 to 60 vol. % C 2 F 6 or CF 4 , each based on a total volume of the gas mixture at 25° C.

19. The method according to claim 14 , wherein the soot body is a porous SiO 2 soot body having a mean density of 0.48 g/cm 3 to 0.77 g/cm 3 and a specific surface area of more than 5 m 2 /g.

20. A fluorinated soot body obtained by the method according to claim 14 .

21. A method for producing a synthetic glass for an optical element comprising the steps of:
i) producing or providing a soot body;
ii) fluorinating the soot body according to claim 14 ;
iii) optionally chlorinating the fluorinated soot body; and
iv) vitrifying the fluorinated soot body at a pressure of less than 0.1 bar at a temperature above the fluorination temperature.

22. The method according to claim 21 , wherein the soot body is produced by depositing SiO 2 particles for mass deposition on a substrate that rotates about its longitudinal axis using at least one depositing burner.

23. The method according to claim 21 , wherein the synthetic glass is a glass tube.

24. A glass obtained by the method according to claim 21 .

25. An optical element produced by the method according to claim 21 .

26. A method of producing an optical fiber from the glass according to claim 24 , comprising elongating the glass while forming a substrate tube and coating the glass on an internal wall of the substrate tube.

Assignees

• Heraeus Quarzglas

Inventors

• Trommer Martin
• Schwerin Malte
• Grimm Stephan
• Froehlich Frank
• Kirchhof Johannes

Classifications

• C03B37/018 Primary

  by glass deposition on a glass substrate, e.g. by {inside-, modified-, plasma- or plasma modified-} chemical vapour deposition {[ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod} (C03B37/016 takes precedence; surface treatment of glass by coating with glass C03C17/02) · CPC title

• C03B37/01446 Primary

  Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering (C03B37/01853 takes precedence) · CPC title

• C03B23/047

  by drawing ({C03B23/091} , C03B37/025 takes precedence) · CPC title

• C03C3/06

  with more than 90% silica by weight, e.g. quartz {(C03C3/045 takes precedence)} · CPC title

• C03C2201/12

  containing fluorine (C03C2201/14 takes precedence) · CPC title