Abstract: Stable, aqueous dispersion containing silicon dioxide powder having a hydroxyl group density of 2.5 to 4.7 OH/nm2, which is obtained from a silicon dioxide powder produced by a flame hydrolysis process under acid conditions. The dispersion is produced by incorporating the silicon dioxide powder into an aqueous solution by means of a dispersing device. The dispersion can be used to produce glass articles.

Abstract: Surface-modified, pyrogenically prepared silica is prepared by subjecting the pyrogenically prepared silica, which is in the form of aggregates of primary particles and possesses a BET surface area of 150±15 m2/g, the aggregates having an average area of 12 000-20 000 nm2, an average equivalent circle diameter (ECD) of 90-120 nm and an average circumference of 1150-1700 nm, to surface-modification in a known way. It can be used as a filler for thickening liquid systems.

Abstract: Provided is a crystalline TiO2 powder in the form of aggregated primary particles having a variable sintering stability at a BET surface area of 70-100 m2/g and a rutile content of greater than 10% but less than or equal to 40%, and a process for preparing the crystalline TiO2 powder, which involves: introducing a TiCl4 vapor and, separately therefrom, H2 and a primary air into a mixing chamber to produce a gaseous mixture; igniting the gaseous mixture in a burner to produce a flame, which is burned into a reaction chamber to produce the crystalline TiO2 powder and gaseous substances; and separating the crystalline TiO2 powder from the gaseous substances, wherein the relative amounts of TiCl4 vapor, H2 and primary air are selected to provide crystalline TiO2 powder having the aforementioned BET surface area and rutile content, with the proviso that factor A has a value of 0.1-0.4·105 g/m2 in accordance within the following formula: factor A=105{[(TiCl4 vapor×H2)/(primary air×gaseous mixture)]/BET]}.

Abstract: Process for removing halide compounds adhering to finely divided metal oxide particles by means of steam, wherein the metal oxide particles are applied to the upper part of an upright column and migrate downwards by means of gravity, the steam is applied at the bottom end of the column, the metal oxide particles and the steam are fed counter-currently, the metal oxide particles freed of halide residues are removed at the base of the column, steam and halide residues are removed at the head of the column, wherein the column is heated in such a manner that the temperature difference Tbottom?Ttop between the lower part and the upper part of the column is at least 20° C. and a maximum temperature of 500° C. prevails in the column, and the metal oxide particles have a residence time in the column of from 1 second to 30 minutes.

Abstract: Pyrogenic silicon-titanium mixed oxide powder having • a BET surface area of 200 to 400 m2/g, • a DBP number/BET surface area ratio of 0.5 to 1.2, • a silicon dioxide content of 93.5 to 95.4% by weight and a titanium dioxide content of 4.6 to 6.5% by weight, where the sum of the contents is greater than 99.7% by weight. Dispersion comprising the pyrogenic silicon-titanium mixed oxide powder. Process for preparing a titanium-containing zeolite proceeding from powder or dispersion.

Abstract: Surface-modified, pyrogenically prepared silica is prepared by subjecting the pyrogenically prepared silica, which is in the form of aggregates of primary particles having a BET surface area of 300±25 m2/g and the aggregates have an average area of 4800-6000 nm2, an average equivalent circle diameter (ECD) of 60-80 nm and an average circumference of 580-750 nm, to surface-modification in a known way. It can be used as a filler for controlling the rheology of liquid silicone rubber (LSR) systems.

Abstract: Electrostatic charge image developing toner Electrostatic charge image developing toner containing external additives comprising pyrogenically prepared surface modified silicon-dioxide-titanium mixed oxides.

Abstract: Surface-modified, pyrogenically prepared silica is prepared by subjecting the pyrogenically prepared silica, which is in the form of aggregates of primary particles and possesses a BET surface area of 200±25 m2/g, the aggregates having an average area of 7000 to 12 000 nm2, an average equivalent circle diameter (ECD) of 80 to 100 nm and an average circumference of 850 to 1050 nm, to surface-modification in a known way. It can be used for thickening liquid systems.

Abstract: Process for preparing a silicon dioxide granule having a specific surface area of less than 1 m2/g and a proportion of impurities of less than 50 ppm, in which a) a silicon dioxide powder with a tamped density of 15 to 190 g/l, b) is compacted to slugs which are subsequently crushed, the slug fragments having a tamped density of 210 to 800 g/l, and c) the slug fragments are treated with one or more reactive compounds at 400 to 1100° C.

Abstract: Silica glass granule having the following features: Area: 100 to 5000 ?m2, ECD: 5 to 100 ?m, Circumference: 20 to 400 ?m, Maximum diameter: 10 to 140 ?m, Minimum diameter: 5 to 80 ?m, where all values are medium values, Specific BET surface area: <1 m2/g Impurities: <50 ppm It is prepared by a) compacting pyrogenic silicon dioxide powder with a tamped density of 15 to 190 g/1 to slugs, b) subsequently crushing them and removing slug fragments with a diameter of <100 ?m and >800 ?m, c) the slug fragments having a tamped density of 300 to 600 g/l, and d) subsequently treating them at 600 to 1100° C. in an atmosphere which comprises one or more compounds which are suitable for removing hydroxyl groups, and e) then sintering them at 1200° C. to 1400° C.

Abstract: Aluminium oxide powder produced by flame hydrolysis and consisting of aggregates of primary particles, having a BET surface area of from 100 to 250 m2/g, a dibutyl phthalate absorption of from 50 to 450 g/100 g of aluminium oxide powder, which powder shows only crystalline primary particles in high-resolution TEM pictures.

Abstract: A crystalline titanium dioxide powder, containing aggregated primary particles, wherein a BET surface area of the aggregated primary particles is from 30 to 65 m2/g, and a rutile content of a sum of crystalline modifications in the crystalline titanium dioxide is from of 50-70%.

Abstract: 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.

Abstract: Silicon titanium mixed oxide powder having the following features: BET surface area of 5 to 300 m2/g, silica content, based on the total amount of the mixed oxide powder, of ?0.1 to <0.5% by weight, titanium dioxide content, based on the total amount of the mixed oxide powder, of ?99.0% by weight, sum of the proportions of silica and titanium dioxide, based on the total amount of the mixed oxide powder, ?99.5% by weight, titanium dioxide content of the primary particles comprising intergrown rutile and anatase phases, silica content of the primary particles amorphous. It is prepared by allowing the vapours of one or more, in each case oxidizable and/or hydrolyzable titanium and silicon compounds to react in a high temperature zone with oxygen and/or steam, cooling the reaction mixture after the reaction and separating off the pulverulent solid from gaseous substances. Dispersion containing the silicon titanium mixed oxide powder. Substrate coated with the silicon titanium mixed oxide powder.

Abstract: Dispersion comprising water and mixed potassium silicon oxide powder, where—the mixed oxide powder is in the form of aggregates of primary particles, has a BET surface area of 100 to 400 m2/g, has an average aggregate diameter in the dispersion of less than 100 nm, and possesses a potassium fraction of 0.05% to 1.5% by weight, calculated as K2O and based on the mixed oxide powder, and—the dispersion has a fraction of mixed oxide powder in the dispersion of 25% to 40% by weight, the sum of water and mixed oxide powder is at least 98% by weight and the pH is 9 to 11.5.

Abstract: Flame-hydrolytically produced titanium dioxide powder that is present in the form of aggregates of primary particles, and has a BET surface of 20 to 200 m²/g, a half width (HW) [nm] of the primary particle distribution of HW = a×BETf where a = 670×10?9 m³/g and ?1.3 ≤ f ≤ ?1.0 and the proportion of particles with a diameter of more than 45 &mgr;m lies in a range from 0.0001 to 0.05 wt. %. The powder is produced by a process in which a titanium halide is vapourised at temperatures of less than 200°C.

Abstract: Stable, aqueous dispersion containing silicon dioxide powder having a hydroxyl group density of 2.5 to 4.7 OH/nm2, which is obtained from a silicon dioxide powder produced by a flame hydrolysis process under acid conditions. The dispersion is produced by incorporating the silicon dioxide powder into an aqueous solution by means of a dispersing device. The dispersion can be used to produce glass articles.

Abstract: Stable, aqueous dispersion containing silicon dioxide powder having a hydroxyl group density of 2.5 to 4.7 OH/nm2, which is obtained from a silicon dioxide powder produced by a flame hydrolysis process under acid conditions. The dispersion is produced by incorporating the silicon dioxide powder into an aqueous solution by means of a dispersing device. The dispersion can be used to produce glass articles.

Abstract: Titanium-aluminium mixed oxide powder with a proportion of aluminium oxide of less than 1 wt. % or a proportion of titanium dioxide of less than 5 wt. %, wherein the sum of the proportions of titanium dioxide and aluminium oxide is at least 99.7 wt. %. It is produced by transferring a vaporous starting compound of the quantitatively greater component of the mixed oxide into a mixing chamber by means of primary air and a vaporous starting compound of the quantitatively smaller component of the mixed oxide by means of an inert gas, and burning the mixture mixed with hydrogen in a mixing chamber into a reaction chamber. It can be used as a catalyst support.

Abstract: Surface-modified silicas Surface-modified, highly structured, potassium oxide-doped silicas, characterized by BET surface area, m2/g: 25-400 average primary particle size, nm: 5-50 pH: 3-10 carbon content, % by weight: 0.1-10 potassium oxide content, % by weight: 0.000001-40 are prepared by subjecting a potassium oxide-doped silica to surface modification. It can be used as a filler in silicone rubber compositions.