摘要:
A method for producing ultra-high purity, optical quality, glass articles is disclosed which involves: 1. compacting metaloxide or metalloidoxide to granules having a mean particle size of less than about 1 millimeter; 2. optionally fully sintering the granules to produce high purity, artificial sand; 3. casting the artificial sand by conventional techniques, such as, slip casting, to form a high density, porous, green body; 4. optionally drying and partially sintering the green body; 5. optionally fully sintering the green body under vacuum; and 6. optionally hot isostatic pressing the green body.
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.
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:
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:
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:
A dispersion containing a high-surface-area, pyrogenically-produced aluminium oxide with a surface area and BET of more than 115 m2/g and a Sears number of more than 8 ml/2 g, is produced by mixing a high-surface-area, pyrogenically-produced aluminium oxide having a BET specific surface area of more than 115 m2/g and a Sears number of more than 8 ml/2 g, with water, setting a pH value of 2 to 11 (preferably 3 to 8) and dispersing the mixture by the introduction of controlled shearing forces.It can be used for the production of Inkjet media, digital imaging products and other printing medium.
摘要:
A dispersion containing a high-surface-area, pyrogenically-produced aluminium oxide with a surface area and BET of more than 115 m2/g and a Sears number of more than 8 ml/2 g, is produced by mixing a high-surface-area, pyrogenically-produced aluminium oxide having a BET specific surface area of more than 115 m2/g and a Sears number of more than 8 ml/2 g, with water, setting a pH value of 2 to 11 (preferably 3 to 8) and dispersing the mixture by the introduction of controlled shearing forces.It can be used for the production of Inkjet media, digital imaging products and other printing medium.
摘要:
Aqueous dispersions of a pyrogenically-produced aluminum oxide are prepared form a mixture containing water, additives and a high-surface-area pyrogenically-produced aluminum oxide with a BET specific surface area of more than 115 m2/g and a Sears number of more than 8 ml/2 g using controlled high shearing conditions. Prior to subjecting the mixture to high shear conditions, the pH of the mixture is adjusted to a value between of 2 to 11 (preferably 3 to 8). The aqueous dispersion has a mean particle size distribution of d50