Method for forming fused quartz using deuterium
View Patent ↗A silica deposition tube is fused in a deuterium (D 2 ) gas atmosphere and optionally baked in a deuterium (D 2 ) gas atmosphere to substantially reduce the hydrogen content in the tube for decreased fiber attenuation. Alternatively, raw silica material is pre-treated in D 2 gas followed by fusing of the raw silica tube in a D 2 gas environment.
1. A method for forming an elongated fused quartz article comprising the steps of:
a) feeding a generally quartz (SiO 2 ) material in loose, freely flowing particulate form into a furnace;
b) fusing the loose, freely flowing particulate quartz (SiO 2 ) material in a melting zone of the furnace under a gas atmosphere comprising a molecular deuterium (D 2 ) gas to provide an article of fused quartz;
c) drawing the article from the furnace; and
d) optionally, baking the article in a gas atmosphere comprising a deuterium gas.
2. The method of claim 1 further comprising the step of heat treating the article drawn from the furnace in a substantially hydrogen-free gas atmosphere or vacuum.
3. The method of claim 1 wherein the gas atmosphere of steps b) or d) further comprises an inert gas or a mixture of inert gases.
4. The method of claim 3 wherein the D 2 gas and inert gas or mixture of inert gases are present in a volume ratio of about 20% D 2 and about 10% inert gas or mixture of inert gases.
5. The method of claim 3 wherein the D 2 gas and inert gas or mixture of inert gases are present in a volume ratio of about 90% D 2 and about 10% inert gas or mixture of inert gases.
6. A method for forming an elongated fused quartz article comprising the steps of:
a) feeding a generally quartz (SiO 2 ) material in particulate form into a furnace;
b) fusing the quartz (SiO 2 ) material in a melting zone of the furnace under a gas atmosphere comprising a molecular deuterium (D 2 ) gas to provide an article of fused quartz;
c) drawing the article from the furnace; and
d) optionally, baking the article in a gas atmosphere comprising a deuterium gas;
wherein the gas atmosphere of steps b) or d) further comprises an inert gas or a mixture of inert gases and wherein the dew point of the gas atmosphere of step b) is about −30° C. to about 80° C.
7. The method of claim 6 wherein the dew point of the gas atmosphere of step b) is about −20° C. to about 10° C.
8. The method of claim 1 being a continuous process.
9. The method of claim 1 wherein the article is a deposition tube.
10. The method of claim 1 wherein the article is a sleeve tube.
11. The method of claim 9 wherein the deposition tube has a hydrogen content of about 5×10 −11 mol/g to about 5×10 −8 mol/g.
12. The method of claim 1 wherein the baking is carried out at a temperature of about 200° C. to about 1500° C.
13. A method for forming an elongated fused quartz article comprising the steps of:
a) pretreating a generally quartz (SiO 2 ) material in a gas atmosphere comprising a molecular deuterium (D 2 ) gas, said generally quartz (SiO 2 ) material is in particulate form;
b) feeding the pretreated quartz (SiO 2 ) material into a furnace;
c) fusing the pretreated quartz (SiO 2 ) material in a melting zone of the furnace under a gas atmosphere comprising a molecular deuterium (D 2 ) gas or a substantially hydrogen-free gas;
d) drawing the fused SiO 2 material from the furnace to form the elongated fused quartz article; and
e) heat treating the drawn article in a substantially hydrogen-free gas atmosphere or vacuum.
14. The method of claim 13 being a continuous process.
15. The method of claim 13 wherein the article is a deposition tube.
16. The method of claim 13 wherein the article is a sleeve tube.
17. The method of claim 13 further comprising the step of:
e) baking the fused SiO 2 article in a gas atmosphere comprising a deuterium gas.
18. A method for forming a fused quartz article comprising the steps of:
a) providing a generally quartz (SiO 2 ) material in loose, freely flowing particulate form; and
b) fusing the loose, freely flowing particulate quartz (SiO 2 ) material in a gas atmosphere comprising a molecular deuterium (D 2 ) gas to form the quartz article.
19. The method of claim 18 wherein the gas atmosphere further comprises an inert gas or a mixture of inert gases.
20. The method of claim 18 further comprising the step of:
c) heat treating the fused SiO 2 article in a substantially hydrogen-free gas atmosphere.
21. The method of claim 20 wherein the heat treating is carried out at about 200° C. to about 1500° C.
22. The method of claim 18 wherein the article is a deposition tube.
23. The method of claim 18 wherein the article is a sleeve tube.