Granular quartz glass product
AssigneeDynamit Nobel Aktiengesellschaft
InventorsArnold Lenz, Gerhard Kreuzburg, Rainer Haase
Life of this patent
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Abstract
Method of preparing granular quartz glass which comprises heating a porous granulated silica gel having an alkoxy group content equal to or less than 1 weight percent and a total impurity content of less than 1 part per million, the porous granulated silica gel obtained by hydrolysis of an orthosilicic acid ester of an aliphatic alcohol at a temperature up to 1400.degree. C.
Claims4
A quartz glass consisting essentially of silica, said quartz glass containing alkoxy groups, said alkoxy groups present in an amount of less than 1 weight percent, said quartz glass having a total impurity content of less than 1 part per million, said quartz glass having a surface area, measured in accordance with BET, of approximately 400 to 800 square meters per gram prepared by a process consisting essentially of:
- A. Forming a silicic acid ester of an alcohol selected from the group consisting of a C.sub.1 -C.sub.5 aliphatic alcohol, a C.sub.2 -C.sub.8 alkanol wherein the carbon chain of the alkyl group can be interrupted by one or more oxygen atoms and a C.sub.2 -C.sub.5 glycol by reacting silicon or ferrosilicon with said alcohol;
- B. Hydrolyzing said silicic acid ester by contacting the same with 105-500 percent of the stoichiometrically necessary amount of water, said water having a pH of 2-5 to thereby form a silica gel;
- C. Gelling said silica sol by subjecting it to an elevated temperature up to 100.degree. C.;
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- D. Drying said gel by heating it at increasing temperatures up to 300.degree. C. until the silica gel achieves a free flowing state.
A quartz glass prepared according to a process consisting essentially of:
- A. Forming a silicic acid ester of an alcohol selected from the group consisting of a C.sub.1 -C.sub.5 aliphatic alcohol, a C.sub.2 -C.sub.8 alkanol wherein the carbon chain of the alkyl group can be interrupted by one or more oxygen atoms and a C.sub.2 to C.sub.5 glycol by reacting silicon or ferrosilicon with said alcohol;
- B. Hydrolyzing said silicic acid ester by contacting the same with 105-500 percent of the stoichiometrically necessary amount of water, said water having a pH of 2-5 to thereby form a silica gel;
- C. Gelling said silicon sol by subjecting it to an elevated temperature up to 100.degree. C.;
- D. Drying said gel by heating at increasing temperatures up to 300.degree. C.;
- E. Comminuting the so-dried gel;
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- F. Heating the so-comminuted gel at increasing temperatures which can be up to a temperature of 1400.degree. C., said quartz glass characterized by the presence of hydroxy groups, said quartz glass containing hydroxy groups in an amount of less than 100 ppm, said quartz glass having a total impurity content of less than 1 ppm.
Dependencies are inferred from the claim text.