Patent US4038370A successfully refreshed from Google Patents.
US4038370A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing high-purity transparent vitreous silica
Assignee: Sumco Techxiv Corp
•
Filing: 1975-09-23
•
Granted: 1977-07-26
•
Expires: 1995-09-23
Abstract
Abstract A method of producing high-purity transparent vitreous silica by supplying to a burner a high-purity silane type gas, and an inert gas, hydrogen gas and oxygen gas to effect the flame hydrolysis, comprising growing highly pure transparent vitreous silica at a controlled atmosphere of said flame that may increase the oxygen defect concentration of the vitreous silica, and thereafter heat-treating said formed body.
Inventors
- 👤 Tadashi Tokimoto
- 👤 Yoshinobu Hiraishi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:58
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/18; C01B33/181; C01B33/183; C03; C03B; C03B19/00; C03B19/14; C03B19/1415; C03B19/1453; C03C; C03C3/00; C03C3/04; C03C3/06; C01P; C01P2006/00; C01P2006/60; C01P2006/80; C03B2201/00; C03B2201/02; C03B2201/03; C03B2201/04; C03B2207/00; C03B2207/30; C03B2207/32; C03B2207/36; C03C2201/00; C03C2201/02; C03C2201/06; C03C2201/20; C03C2203/00; C03C2203/10; C03C2203/20; C03C2203/40
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
157 words
A method of producing high-purity transparent vitreous silica by supplying to a burner a high-purity silane type gas, and an inert gas, hydrogen gas and oxygen gas to effect the flame hydrolysis, comprising forming a high-purity transparent vitreous silica which contains metastable OH of less than 500 ppm through flame hydrolysis while maintaining the flow rate of said hydrogen gas at least more than six times the flow rate of said high-purity silane type gas and maintaining the flow rate of said oxygen gas less than 1.5 times a theoretical supply flow rate required to oxidize completely the silicon in said high-purity silane type gas and the hydrogen which exists when effecting said flame hydrolysis, and heat-treating the transparent vitreous silica obtained at a temperature higher than 800° C. in an inert gas atmosphere for more than 20 hours to reduce the OH content of said transparent vitreous silica to the range from 40 to 60 ppm.
Claim 2
Independent Claim
157 words
A method of producing high-purity transparent vitreous silica by supplying to a burner a high-purity silane type gas, and an inert gas, hydrogen gas and oxygen gas to effect the flame hydrolysis, comprising forming a high-purity transparent vitreous silica which contains metastable OH of less than 500 ppm through flame hydrolysis while maintaining the flow rate of said hydrogen gas at least more than six times the flow rate of said high-purity silane type gas and maintaining the flow rate of said oxygen gas less than 1.5 times a theoretical supply flow rate required to oxidize completely the silicon in said high-purity silane type gas and the hydrogen which exists when effecting said flame hydrolysis, and heat-treating the transparent vitreous silica obtained at a temperature higher than 800° C. in an inert gas atmosphere for more than 20 hours to reduce the OH content of said transparent vitreous silica to the range from 40 to 60 ppm.
Claim 3
Dependent Claim
30 words
A method of claim 1 wherein the high-purity transparent vitreous silica containing metastable OH obtained by the flame hydrolysis is heat-treated at a temperature from 800° C. to 1050° C.
Claim 4
Dependent Claim
21 words
A method of claim 1 wherein the high-purity transparent vitreous silica obtained by the flame hydrolysis is heat-treated for 20-40 hours.
Claim 5
Dependent Claim
23 words
A method of producing high-purity transparent vitreous silica in accordance with claim 1 wherein the inert gas is argon gas or helium gas.
Claim 6
Dependent Claim
41 words
A method of producing high-purity transparent vitreous silica in accordance with claim 1 wherein there are used, as the silane type gases, monosilane (SiH 4 ), dichlorosilane (SiH 2 Cl 2 ) and trichlorosilane (SiHCl 3 ), tetrachlorosilane (SiCl 4 ).
Claim 7
Dependent Claim
27 words
A method of producing high-purity transparent vitreous silica in accordance with claim 1 wherein the heat treatment is carried out on nitrogen gas or argon gas atmosphere.
References Cited (Backward Citations)
US2272342A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-25 | 1981-01-24 | 1981-07-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-25 | 1985-01-24 | 1985-07-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-25 | 1989-01-24 | 1989-07-26 | $7700.00 | Window Closed / Lapsed |