Process for production of synthetic quartz glass
View Patent ↗The present invention relates to a process for production of a synthetic quartz glass having a fluorine concentration of 1,000 mass ppm or more, the process comprising: (a) a step of depositing and growing quartz glass fine particles obtained by flame hydrolysis of a glass forming raw material onto a substrate, to thereby form a porous glass body; (b) a step of keeping the porous glass body in a reaction vessel that is filled with elemental fluorine (F 2 ) or a mixed gas comprising elemental fluorine (F 2 ) diluted with an inert gas and contains a solid metal fluoride, to thereby obtain a fluorine-containing porous glass body; and (c) a step of heating the fluorine-containing porous glass body to a transparent vitrification temperature, to thereby obtain a fluorine-containing transparent glass body.
1. A process for production of a synthetic quartz glass having a fluorine concentration of 1,000 mass ppm or more, the process comprising:
(a) depositing and growing quartz glass fine particles obtained by flame hydrolysis of a glass forming raw material onto a substrate, to thereby form a porous glass body;
(b) keeping the porous glass body in a reaction vessel that is filled with elemental fluorine (F 2 ) or a mixed gas comprising elemental fluorine (F 2 ) diluted with an inert gas and contains a solid metal fluoride, to thereby obtain a fluorine-containing porous glass body; and
(c) heating the fluorine-containing porous glass body to a transparent vitrification temperature, to thereby obtain a fluorine-containing transparent glass body.
2. The production process according to claim 1 , wherein the solid metal fluoride is sodium fluoride.
3. The production process according to claim 1 , further comprising subjecting the inside of the reaction vessel to a degassing treatment before filling the inside of the reaction vessel with elemental fluorine (F 2 ) or a mixed gas obtained by diluting elemental fluorine (F 2 ) with an inert gas in (b).
4. The production process according to claim 1 , further comprising presintering the porous glass body at from 1,100 to 1,350° C. between (a) and (b).
5. The production process according to claim 1 , wherein (b) is carried out a temperature of 200° C. or less.
6. The production process according to claim 1 , wherein (b) is carried out a temperature of 150° C. or less.
7. The production process according to claim 1 , wherein the inert gas comprises nitrogen, helium or argon.
8. The production process according to claim 1 , wherein the transparent vitrification temperature is within the range of from 1,350 to 1,800° C.
9. The production process according to claim 1 , wherein the transparent glass body has a fluorine concentration of 3,000 ppm or more.
10. A process for production of a TiO 2 -containing synthetic quartz glass (TiO 2 —SiO 2 glass) having a fluorine concentration of 1,000 mass ppm or more, the process comprising:
(a) depositing and growing TiO 2 —SiO 2 glass fine particles obtained by flame hydrolysis of an Si precursor and a Ti precursor each serving as a glass forming raw material onto a substrate, to thereby form a porous TiO 2 —SiO 2 glass body;
(b) keeping the porous TiO 2 —SiO 2 glass body in a reaction vessel that is filled with elemental fluorine (F 2 ) or a mixed gas comprising elemental fluorine (F 2 ) diluted with an inert gas and contains a solid metal fluoride, to thereby obtain a fluorine-containing porous TiO 2 —SiO 2 glass body; and
(c) heating the fluorine-containing porous TiO 2 —SiO 2 glass body to a transparent vitrification temperature, to thereby obtain a fluorine-containing transparent TiO 2 —SiO 2 glass body.
11. The production process according to claim 10 , wherein the solid metal fluoride is sodium fluoride.
12. The production process according to claim 10 , further comprising subjecting the inside of the reaction vessel to a degassing treatment before filling the inside of the reaction vessel with elemental fluorine (F 2 ) or a mixed gas obtained by diluting elemental fluorine (F 2 ) with an inert gas in (b).
13. The production process according to claim 10 , further comprising presintering the porous glass body at from 1,100 to 1,350° C. between (a) and (b).
14. The production process according to claim 10 , wherein (b) is carried out a temperature of 200° C. or less.
15. The production process according to claim 10 , wherein (b) is carried out a temperature of 150° C. or less.
16. The production process according to claim 10 , wherein the inert gas comprises nitrogen, helium or argon.
17. The production process according to claim 10 , wherein the transparent vitrification temperature is within the range of from 1,350 to 1,800° C.
18. The production process according to claim 10 , wherein the transparent TiO 2 —SiO 2 glass body has a fluorine concentration of 3,000 ppm or more.