Method for the manufacture of doped quartz glass

Patent metadata

Field	Value
Publication number	US-9878933-B2
Application number	US-201514804673-A
Country	US
Kind code	B2
Filing date	Jul 21, 2015
Priority date	Jul 21, 2014
Publication date	Jan 30, 2018
Grant date	Jan 30, 2018

Abstract

One aspect relates to a method for the manufacture of doped quartz glass. Moreover, one aspect relates to quartz glass obtainable according to the method including providing a soot body, treating the soot body with a gas, heating an intermediate product and vitrifying an intermediate product.

First claim

What is claimed is:

1. A method for the manufacture of doped quartz glass, comprising:
a) providing a soot body, whereby the soot body has a mean density in the range of 18 to 30% relative to the relative density of quartz glass;
b) treating the soot body with a gas comprising a fluorine-containing compound in a process chamber while forming a fluorinated intermediate product (A), whereby the mean density of intermediate product (A) increases by maximally 30% relative to the mean density of the soot body in step a), wherein the treatment of the soot body in step b) takes place at a temperature in a range of 700 to 1,000° C.;
c) heating fluorinated intermediate product (A) in the absence of chlorine to a temperature in the range of 950 to 1,150° C., and above the temperature used for the treatment of the soot body in step b), while forming a fluorinated intermediate product (B), whereby the mean density of fluorinated intermediate product (B) is 40 to 80% of the relative density of quartz glass; and
d) vitrifying the fluorinated intermediate product (B) in a process chamber, whereby the pressure inside the process chamber is lower than the pressure outside the process chamber, while forming the doped quartz glass.

2. The method according to claim 1 , whereby the mean density of fluorinated intermediate product (B) is maximally 60% of the relative density of quartz glass.

3. The method according to claim 1 , characterized in that the fluorine-containing compound is selected from the group consisting of F 2 , SiF 4 , CF 4 , C 2 F 6 , SF 6 , C 3 F 8 , NF 3 , ClF 3 , BF 3 , and fluoro-chloro hydrocarbons.

4. The method according to claim 1 , characterized in that the fraction of fluorine-containing compound in the gas is 15 to 100 vol. % or 60 to 100 vol. %, each relative to the total volume of the gas.

5. The method according to claim 1 , characterized in that the vitrification temperature in step d) is in the range of 1,200 to 1,500° C.

6. The method according to claim 1 , characterized in that the mean density of the fluorinated intermediate product (B) is 50 to 60%, of the relative density of quartz glass.

7. The method according to claim 1 , characterized in that the soot body is dried in step a) at a temperature in the range of 700 to 1,100° C. by thermal and/or chemical means.

8. The method according to claim 1 , characterized in that the vitrification in step d) takes place in a second process chamber that differs from the first process chamber, in which steps b) and c) are performed.

9. The method according to claim 8 , characterized in that the fluorinated intermediate product (B) is subjected to another drying step in the second process chamber before vitrification, whereby the drying takes place at a temperature in the range of 700 to 1,200° C.

10. The method according to claim 1 , further comprising:
a-1) drying the soot body at a temperature in the range of 700 to 1,050° C.;
a-2) as an option, chemically drying the soot body at a temperature in the range of 700 to 1,050° C. in the presence of a chlorine-containing gas;
c-1) as an option, chemically drying the fluorinated intermediate product (B) at a temperature in the range of 700 to 1,100° C. in the presence of a chlorine-containing gas;
c-2) transferring the fluorinated intermediate product (B) into a second process chamber; and
c-3) as an option, heating the fluorinated intermediate product (B) to a temperature above 1,000° C. whereby the pressure inside the process chamber is lower than the pressure outside the process chamber.

11. The method according to claim 1 , characterized in that the second process chamber is one of a vitrification furnace and a multi-chamber sintering furnace.

12. A method for the manufacture of doped quartz glass, comprising:
providing a soot body, the soot body comprising a mean density in the range of 18 to 30% relative to the relative density of quartz glass;
treating the soot body with a gas comprising a fluorine-containing compound in a process chamber while forming a first fluorinated intermediate product, the mean density of the first fluorinated intermediate product increasing by maximally 30% relative to the mean density of the provided soot body, wherein the treatment of the soot body in step b) takes place at a temperature in a range of 700 to 1,000° C.;
heating the first fluorinated intermediate product in the absence of chlorine to a temperature in the range of 950 to 1,150° C., and above the temperature used for the treatment of the soot body in step b), while forming a second fluorinated intermediate product, the mean density of the second fluorinated intermediate product being 40 to 80% of the relative density of quartz glass; and
vitrifying the second fluorinated intermediate product in a process chamber, the pressure inside the process chamber being lower than the pressure outside the process chamber, while forming the doped quartz glass.

Assignees

• Heraeus Quarzglas

Inventors

• Schwerin Malte
• Trommer Martin
• Zwarg Steffen

Classifications

• C03B23/045

  Tools or apparatus specially adapted for re-forming tubes or rods in general, e.g. glass lathes, chucks (C03B23/043 takes precedence) · CPC title

• C03C3/06 Primary

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

• C03B2201/34

  doped with rare earth metals, i.e. with Sc, Y or lanthanides, e.g. for laser-amplifiers · CPC title

• C03C2201/42

  containing titanium · CPC title

• C03B37/01453

  for doping the preform with flourine · CPC title