摘要:
SiO2—TiO2 glasses having a low coefficient of thermal expansion are produced by a molding being produced that consists of SiO2 powder, SiO2—TiO2 powder or TiO2 powder and that contains by way of secondary component a titanium-containing component which is converted into amorphous TiO2.
摘要:
Aqueous dispersion comprising silicon/titanium mixed oxide powder with a BET surface area of 5 to 500 m2/g which has been prepared by flame hydrolysis and has a titanium dioxide content of 0.5 to 20 wt. %, based on the powder, water and at least one pH-regulating substance which can be removed completely from the reaction mixture on heating, the aqueous dispersion having a solids content of between 40 and 80 wt. %. A green body produced therefrom with a green density of between 40 and 85%. A shaped glass article of optical quality with a coefficient of thermal expansion of not more than 0.5×10−6/K produced from the green body.
摘要:
Sintered materials, especially sintered glasses, produced from pyrogenically produced silicon dioxide which has been processed to silicon granulates in a compacting step, and the use of such granulates in the production of formed glass bodies.
摘要:
Sintered materials, especially sintered glasses, produced from pyrogenically produced silicon dioxide which has been processed to silicon granulates in a compacting step, and the use of such granulates in the production of formed glass bodies.
摘要:
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.
摘要:
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 %) &eegr;≦100 m·Pas 3. Thixotropy of Ti (&eegr;(5 rpm))/(&eegr;(50 rpm))≦2 4. BET surface area 30-60 m2/g 5. Compacted bulk=100-160 g/L 6. Original pH≦4.5 can be used for the preparation of dispersions and glass bodies.
摘要:
Pyrogenic silicon dioxide powder with a BET surface area of 30 to 90 m2/g, a DBP index of 80 or less, a mean aggregate area of less than 25000 nm2 and a mean aggregate circumference of less than 1000 nm, wherein at least 70% of the aggregates have a circumference of less than 1300 nm. It is prepared by mixing at least one silicon compound in vapor form, a free-oxygen-containing gas and a combustible gas in a burner of known construction, igniting this gas mixture at the mouth of the burner and burning it in the flame tube of the burner, separating the solid obtained from the gas mixture and optionally purifying, wherein the oxygen content of the free-oxygen-containing gas is adjusted so that the lambda value is greater than or equal to 1, the gamma value is between 1.2 and 1.8, the throughput is between 0.1 and 0.3 kg SiO2/m3 of core gas mixture and the mean normalized rate of flow of gas in the flame tube at the level of the mouth of the burner is at least 5 m/s. The powder can be used as a filler. A dispersion containing the powder according to the invention. The powder can be used as a filler in rubber, silicone rubber and plastics. The dispersion can be used to prepare glass items.
摘要:
Pyrogenic silicon dioxde powder with a BET surface area of 30 to 90 m2/g, a DBP index of 80 or less, a mean aggregate area of less than 25000 nm2 and a mean aggregate circumference of less than 1000 nm, wherein at least 70% of the aggregates have a circumference of less than 1300 nm, It is prepared by mixing at least one silicon compound in vapour form, a free-oxygen-containing gas and a combustible gas in a burner of known construction, igniting this gas mixture at the mouth of the burner and burning it in the flame tube of the burner, separating the solid obtained from the gas mixture and optionally purifying, wherein the oxygen content of the free-oxygen-containing gas is adjusted so that the lambda value is greater than or equal to 1, the gamma value is between 1.2 and 1.8, the throughput is between 0.1 and 0.3 kg SiO2/m3 of core gas mixture and the mean normalised rate of flow of gas in the flame tube at the level of the mouth of the burner is at least 5 m/s. The powder can be used as a filler. A dispersion containing the powder according to the invention. The powder can be used as a filler in rubber, silicone rubber and plastics. The dispersion can be used to prepare glass items.
摘要:
Sintered materials, especially sintered glasses, produced from pyrogenically produced silicon dioxide which has been processed to silicon granulates in a compacting step, and the use of such granulates in the production of formed glass bodies.
摘要:
Glass is produced by depositing presintering composition on a preform set into move in front of a plasma torch which moves back and forth substantially parallel to a longitudinal direction of the preform, a first feed duct feeds the plasma with grains of the presintering composition while optionally a second feed duct feeds the plasma with a fluorine or chlorine compound, preferably a fluorine compound, mixed with a carrier gas.