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US 6,890,873 B2Granted
Glass prepared from pyrogenically prepared silicon dioxide
AssigneeDegussa AG
InventorsMonika Oswald, Gerrit Schneider, Klaus Deller
Life of this patent
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Abstract
Pyrogenically prepared silicon dioxide with the following physicochemical properties: 1. Average particle size (D50 value) D50≧150 nm (dynamic light scattering, 30 wt %) 2. Viscosity (5 rpm, 30 wt %) η≦100 m·Pas 3. Thixotropy of Ti (η(5 rpm))/(η(50 rpm))≦2 4. BET surface area 30-60 m2/g 5. Compacted bulk=100-160 g/L 6. Original pH≦4.5 that can be used for the preparation of dispersions and glass bodies.
Claims5
A method of making glass comprising:
- forming a dispersion of a pyrogenic silica with water, by mixing said pyrogenic silica with water,
- gelling the dispersion,
- drying the dispersion to obtain a microporous body,
- sintering the body at a sufficient temperature for a sufficient time to produce a sintered glass body;
- and further comprising
- adding acetic acid ethyl ester to the dispersion wherein the pyrogenic silica has the following physiochemical properties:
- a) average particle size (D50 value, D50≧150 nm dynamic light scattering, 30 wt %);
- b) viscosity (5 rpm, 30 wt %) η≦100 m·Pas;
- c) thixotropy of T1:
- (η(5 rpm))/(η(50 rpm))≦2;
- d) BET surface area 30-60 m2/g;
- e) compacted bulk=100-160 g/L;
- and
- f) original pH≦4.5.
11 more elements
A method of making a sintered glass comprising:
- mixing a pyrogenically prepared silicon dioxide with water to form a homogeneous dispersion, said pyrogenically prepared silicon dioxide having the following physicochemical properties:
- a) average particle size (D50 value) D50≧150 nm (dynamic light scattering, 30 wt %);
- b) viscosity (5 rpm, 30 wt %) η≦100 m·Pas;
- c) thixotropy of Ti:
- (η(5 rpm)/(η50 rpm))≦2;
- d) BET surface area 30-60 m2/g;
- e) compacted bulk=100-160 g/L;
- and
- f) original pH≦4.5;
- pouring the dispersion into a mold, gellng the dispersion in the mold to form a gelled body, removing the gelled body from the mold, and drying the gelled body to form a microporous green body, sintering the green body by zone sintering under vacuum to thereby obtain a sintered glass body.
7 more elements
Dependencies are inferred from the claim text.