# US 8,539,793 B2 · Method of molding synthetic silica glass molded body

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- Number: US 8,539,793 B2
- Document ID: US8539793B2
- Status: Granted
- Kind: B2
- Application number: 13/567,837
- Filed: 2012-08-06
- Published: 2012-11-29
- Granted: 2013-09-24
- Earliest claimed: 2005-03-01
- Assignees: Nikon Corporation
- Applicants: Masafumi Mizuguchi; Tetsuya Abe
- Inventors: Masafumi Mizuguchi; Tetsuya Abe
- Web page: https://patentgrep.com/patent/US8539793B2

## CPC

- G01N 21/64: Fluorescence; Phosphorescence
- C03B 11/08: for making solid articles, e.g. lenses
- C03B 23/0013: {by pressing (C03B21/04, C03B23/02, C03B23/04, C03B23/18, C03B23/26 take precedence)}
- C03B 40/02: by lubrication; Use of materials as release or lubricating compositions
- C03C 3/06: with more than 90% silica by weight, e.g. quartz {(C03C3/045 takes precedence)}
- C03C 23/0075: {Cleaning of glass (specially adapted to plate glass B08B11/00)}
- G01N 21/6402: {Atomic fluorescence; Laser induced fluorescence}
- C03B 2201/03: Impurity concentration specified
- C03C 2201/32: containing aluminium (C03C2201/36 takes precedence)
- C03C 2201/40: containing transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn
- C03C 2203/52: Heat-treatment
- Y02P 40/57: Improving the yield, e-g- reduction of reject rates
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method of molding a synthetic silica glass molded body by accommodating a synthetic silica glass block in a mold provided with a pressing portion, and by pressing the block while heating, the method including: washing the synthetic silica glass block so that a concentration of copper which is present on the surface of the synthetic silica glass block is 2 ng/cm2 or less; heating high purity carbon powders with a content of copper and aluminium; heating the mold at a temperature condition of 1700° C. to 1900° C.; applying the powders before accommodating the block in the mold; and molding the block in a predetermined form by pressing the block while heating within a hold temperature range of 1500° C. to 1700° C., after accommodating the washed block in the mold.

## Claims

### Claim 1

A method of molding a synthetic silica glass molded body by accommodating a synthetic silica glass block in a mold provided with a pressing portion, and by pressing the block while heating, the method comprising:
washing the synthetic silica glass block so that a concentration of copper which is present on the surface of the synthetic silica glass block is 2 ng/cm2 or less, and so that a concentration of aluminum thereon is 10 ng/cm2 or less, before accommodating the synthetic silica glass block in the mold;
heating high purity carbon powders in which a content of copper is 40 wt.ppb or less and a content of aluminum is 100 wt.ppb or less at a temperature condition of 1200° C. to 1900° C.;
heating the mold at a temperature condition of 1700° C. to 1900° C.;
after the heating the high purity carbon powders and the heating the mold, applying the high purity carbon powders on the inner surface of the mold, before accommodating the synthetic silica glass block in the mold; and
molding the synthetic silica glass block in a predetermined form by pressing the block using the pressing portion while heating the block so that a temperature of the block is maintained within a hold temperature range of 1500° C. to 1700° C., after accommodating the washed synthetic silica glass block in the mold.

### Claim 2 (depends on 1)

The method of molding a synthetic silica glass molded body according to claim 1, wherein the heating temperature in the heating the high purity carbon powders is in a condition of 1200° C. to 1600° C.

### Claim 3 (depends on 1)

The method of molding a synthetic silica glass molded body according to claim 1, wherein the heating the high purity carbon powders and the heating the mold are simultaneously performed.

### Claim 4 (depends on 1)

The method of molding a synthetic silica glass molded body according to claim 1, wherein a content of copper in the mold after the heating step is 80 wt.ppb or less.

### Claim 5 (depends on 1)

The method of molding a synthetic silica glass molded body according to claim 1, wherein the applied amount of the high purity carbon powders in the applying the high purity carbon powders is 7 mg/cm2 to 200 mg/cm2.

### Claim 6 (depends on 1)

The method of molding a synthetic silica glass molded body according to claim 1, wherein a concentration of OH group in the synthetic silica glass block is 900 ppm to 1300 ppm by mass.

### Claim 7 (depends on 1)

The method of molding a synthetic silica glass molded body according to claim 1, wherein, in the molding the synthetic silica glass block, the silica glass block is pressed in the predetermined form by means of the pressing portion so that a maximum pressure is 0.2 kg/cm2 to 1.0 kg/cm2.