Preparation of an opaque quartz glass body

Patent metadata

Field	Value
Publication number	US-11236002-B2
Application number	US-201616062303-A
Country	US
Kind code	B2
Filing date	Dec 16, 2016
Priority date	Dec 18, 2015
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

One aspect relates to a process for the preparation of a quartz glass body. The process includes providing a silicon dioxide granulate from a pyrogenically produced silicon dioxide powder, making a glass melt out of silicon dioxide granulate, and making a quartz glass body out of at least part of the glass melt. The size of the quartz glass body is reduced to obtain a quartz glass grain. The quartz glass body is processed to make a preform and an opaque quartz glass body is made from the preform. One aspect further relates to an opaque quartz glass body which is obtainable by this process. One aspect further relates to a reactor and an arrangement, which are each obtainable by further processing of the opaque quartz glass body.

First claim

The invention claimed is:

1. A process for the preparation of an opaque quartz glass body comprising:
providing a silicon dioxide granulate, wherein the silicon dioxide granulate has been prepared from pyrogenically produced silicon dioxide powder;
making a glass melt out of the silicon dioxide granulate in a melting crucible;
making a quartz glass body out of at least part of the glass melt;
reducing the size of the quartz glass body to obtain a quartz glass grain;
processing the quartz glass grain into a preform; and
making the opaque quartz glass body from the preform.

2. The process according to claim 1 , wherein the melting crucible has at least one inlet and an outlet and wherein the inlet is arranged above the outlet.

3. The process according to claim 1 , wherein the reduction in size takes place by high voltage discharge pulses.

4. The process according to claim 1 , wherein the quartz glass grain comprises at least one of the following:
an OH content of less than 500 ppm;
a chlorine content of less than 60 ppm;
an aluminium content of less than 200 ppb;
a BET surface area of less than 1 m 2 /g;
a bulk density in a range from 1.1 to 1.4 g/cm 3 ;
a particle size D 50 for the melting in a range from 50 to 500 μm;
a particle size D 50 for a slurry in a range from 0.5 to 5 mm;
a metal content of metals different to aluminium of less than 2 ppm; and
viscosity (p=1013 hPa) in a range from log 10 (η (1250° C.)/dPas)=11.4 to log 10 (η (1250° C.)/dPas)=12.9 or log 10 (η (1300° C.)/dPas)=11.1 to log 10 (η (1300° C.)/dPas)=12.2 or log 10 (η (1350° C.)/dPas)=10.5 to log 10 (η (1350° C.)/dPas)=11.5;
wherein the ppm and ppb are each based on the total weight of the quartz glass grain.

5. The process according to claim 1 , wherein a melt energy is transferred to the silicon dioxide granulate via a solid surface.

6. The process according to claim 1 , wherein the silicon dioxide granulate comprises at least one of the following:
a BET surface area in a range from 20 to 50 m 2 /g;
a mean particle size in a range from 50 to 500 μm;
a bulk density in a range from 0.5 to 1.2 g/cm 3 ;
a carbon content of less than 50 ppm;
an aluminium content of less than 200 ppb;
a tamped density in a range from 0.7 to 1.0 g/cm 3 ;
a pore volume in a range from 0.1 to 2.5 mL/g;
an angle of repose in a range from 23 to 26°,
a particle size distribution D 10 in a range from 50 to 150 μm;
a particle size distribution D 50 in a range from 150 to 300 μm; and
a particle size distribution D 90 in a range from 250 to 620 μm,

wherein the ppm is based on the total weight of the silicon dioxide granulate.

7. The process according to claim 1 , wherein the silicon dioxide powder can be prepared from a compound selected from a group consisting of siloxanes, silicon alkoxides and silicon halides.

8. The process according to claim 1 , wherein processing the quartz glass grain into a preform comprises:
making a slurry of the quartz glass grain with a liquid; and
forming a preform from the slurry by removing liquid.

9. The process according to claim 1 , wherein processing the quartz glass grain into a preform comprises:
introducing the quartz glass grain into a rotating hollow mold.

10. The process according to claim 1 , wherein a formation of the opaque quartz glass body comprises a sintering.

11. The process according to claim 1 , wherein the quartz glass grain comprises a bulk density in a range from 1.1 to 1.4 g/cm 3 and a BET surface area of less than 1 m 2 /g.

Assignees

• Heraeus Quarzglas

Inventors

• Otter Matthias
• Hünermann Michael
• Nielsen Nils Christian
• Wessely Frank
• Schreiber Andreas
• Roos Björn
• Scheich Gerrit

Classifications

• C03B19/066 Primary

  for the production of quartz or fused silica articles (other processes specially adapted for the production of quartz or fused silica articles C03B20/00) · CPC title

• C03C2201/32

  containing aluminium (C03C2201/36 takes precedence) · CPC title

• C03C1/022

  Purification of silica sand or other minerals · CPC title

• C03B2201/03

  Impurity concentration specified · CPC title

• C03C2203/10

  Melting processes · CPC title