Abstract: Stable, pourable silicon dioxide dispersion, in which the average, number-related aggregate diameter of the silicon dioxide particles in dispersion is less than 200 nm, and which comprises at least 35 wt. % of a silicon dioxide powder, 3 to 35 wt. % of at least one polyol, 20 to 60 wt. % of water, 0 to 10 wt. % of an additive and a substance having an alkaline action in an amount such that a pH of 10<pH<12 is established. It can be prepared by a procedure in which silicon dioxide powder is introduced into water and a polyol in a rotor/stator machine, the pH being less than 5, and the mixture is dispersed until the current uptake of the rotor/stator machine is largely constant, and a substance having an alkaline action is subsequently added in an amount such that a pH of the dispersion of 10<pH<12 results, the substance having an alkaline reaction being added so rapidly that no gel formation takes place.

Abstract: Slurry which contains a) from (50) to (80)% by weight of refractory particles having an average particle size of from (0.5) m to (150) m, b) from (5) to (35)% by weight of aluminum oxide particles having an average particle diameter of less than (300) nm and c) from (5) to (35)% by weight of water and d) a pH of from (5) to (12). Process for producing the slurry using a dispersion, and also the dispersion itself. Process for producing a casting mold, and also the casting mold itself.

Abstract: Aluminum oxide dispersion, which is stable in a pH range 5 from 5 to 9 and has an aluminum oxide content of at least 40 wt. %, obtainable by dispersing pyrogenically produced aluminum oxide particles in an aqueous phase, wherein one or several at least dibasic hydroxycarboxylic acids present dissolved in the dispersion and at least one salt of a 10 dialkali metal hydrogen phosphate and/or alkali metal dihydrogen phosphate are added to the aqueous phase each mutually independently in a quantity of 0.3?3×10?6 mol/m2 of aluminum oxide specific surface area.

Abstract: Process for the production of an aqueous dispersion of pyrogenically produced metal oxide and metalloid oxide powders with a BET surface area of between 5 and 600 m2/g, with a metal oxide or metalloid oxide content in the dispersion of between 5 and 25 wt. %, comprising the following steps: water, which is optionally adjusted to pH values of between 2 and 4 by adding acids, is circulated from a receiving vessel via a rotor/stator machine, and metal oxide or metalloid oxide powder is introduced, using a feed device, into the shear zone between the slots in the rotor teeth and the stator slots, continuously or discontinuously and with the rotor/stator machine running, in a quantity such that a predispersion with a solids content of between 20 and 40 wt.

Abstract: Dispersion containing, in addition to water, 0.5 to 20 wt. % of hydrophobic silica, 0.01 to 10 wt. % of a gelling or viscosity-increasing additive, 0.1 to 1 wt. % of a preservative and 0 to 1 wt. % of a surface-active substance. It is prepared by a procedure in which the individual components are dispersed successively or together into the water and in this procedure the individual components are deaerated before and/or during the addition or the dispersion is deaerated during the individual dispersing steps. The dispersion can be employed as an insecticide.

Abstract: Provided is a process for preparing surface-modified silicon dioxide particles with a mean particle diameter of at most 100 nm, involving (A) high-pressure grinding of a predispersion having (i) surface-modified silicon dioxide particles which are at least partly aggregated, are bonded to the surface-modifying component via Si—O—Si bonds, and still have reactive groups on their surface; (ii) an organosilicon compound which has a silicon-carbon bond and a functional group which can react with the reactive groups to form a covalent Si—O—Si bond; and (iii) a solvent, to form a dispersion; and (B) removing the liquid phase of the dispersion. Also provided are redispersible, surface-modified silicon dioxide particles obtained by this process, and their use in toner powders, silicone rubber, adhesives, and scratch-resistance surface coatings.

Abstract: Aqueous dispersion which comprises hydrophobized silicon dioxide particles and in each case one or more dispersing additives, a basic composition, and which is free of color pigments, inactive fillers and binders, in which the hydrophobized silicon dioxide particles have a methanol wettability of 30 to 60 and are present in the dispersion with a proportion of 0.

Abstract: Process for the infiltration of porous ceramic components, in which a dispersion containing metal oxide particles and having a metal oxide content of at least 30% by weight, based on the dispersion, is used, where the particle size distribution d50 of the metal oxide particles is not more than 200 nm.

Abstract: Slurry which contains a) from (50) to (80) % by weight of refractory particles having an average particle size of from (0.5) m to (150) m, b) from (5) to (35) % by weight of aluminium oxide particles having an average particle diameter of less than (300) nm and c) from (5) to (35) % by weight of water and d) a pH of from (5) to (12). Process for producing the slurry using a dispersion, and also the dispersion itself. Process for producing a casting mould, and also the casting mould itself.

Abstract: An aqueous dispersion for use as a finishing agent for textiles, wherein the dispersion contains a pyrogenically produced, aggregated silicon dioxide powder and a cationic polymer which is soluble in the dispersion, wherein the cationic polymer is present in a quantity such that the particles of the silicon dioxide powder exhibit a positive zeta potential.

Abstract: Process for the production of an aqueous dispersion of pyrogenically produced metal oxide and metalloid oxide powders with a BET surface area of between 5 and 600 m2/g, with a metal oxide or metalloid oxide content in the dispersion of between 5 and 25 wt. %, comprising the following steps: water, which is optionally adjusted to pH values of between 2 and 4 by adding acids, is circulated from a receiving vessel via a rotor/stator machine, and metal oxide or metalloid oxide powder is introduced, using a feed device, into the shear zone between the slots in the rotor teeth and the stator slots, continuously or discontinuously and with the rotor/stator machine running, in a quantity such that a predispersion with a solids content of between 20 and 40 wt.

Abstract: Process for preparing a dispersion of surface-modified silicon dioxide particles having an average particle diameter of not more than 100 nm by high-pressure milling of a preliminary dispersion comprising a) 10% to 50% by weight of surface-modified silicon dioxide particles, b) at least one glycol monoether of the general formula (A): H3C(CH2)m—O—(CH2)n—[O—(CH2)o]p—OH, c) at least one carboxylic ester of the general formula (B): H2x+1Cx—O—CH2—(CHR)—[O—CHR]y—O—C(?O)—CzH2z+1, d) the molar ratio A/B being 10:90 to 40:60 and m, n, o, p, x, y and z being independent of one another. Dispersion obtainable by this process. Process for producing granules of surface-modified silicon dioxide particles by separating off the liquid phase of the dispersion. Granules obtainable by this process. Use of dispersion and granules in coating materials.

Abstract: Process for preparing surface-modified silicon dioxide particles with a mean particle diameter of at most 100 nm, comprising the steps of: a) providing a predispersion b) high-pressure grinding of the predispersion to form a dispersion c) removing the liquid phase of the dispersion, the predispersion comprising a1) surface-modified silicon dioxide particles which are at least partly aggregated, are bonded to the surface-modifying component via Si—O—Si bonds and still have reactive groups on their surface, a2) one or more organosilicon compounds which have at least one silicon-carbon bond and at least one functional group which can react with the reactive groups to form a covalent Si—O—Si bond, and a3) one or more solvents. Redispersible, surface-modified silicon dioxide particles obtainable by this process. Use of these in toner powders, silicone rubber, adhesives and scratch-resistance surface coatings.

Abstract: An aqueous dispersion for use as a finishing agent for textiles, wherein the dispersion contains a pyrogenically produced, aggregated silicon dioxide powder and a cationic polymer which is soluble in the dispersion, wherein the cationic polymer is present in a quantity such that the particles of the silicon dioxide powder exhibit a positive zeta potential.

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: Aqueous dispersion which comprises hydrophobized silicon dioxide particles and in each case one or more dispersing additives, a basic composition, and which is free of colour pigments, inactive fillers and binders, in which the hydrophobized silicon dioxide particles have a methanol wettability of 30 to 60 and are present in the dispersion with a proportion of 0.

Abstract: Stable, pourable silicon dioxide dispersion, in which the average, number-related aggregate diameter of the silicon dioxide particles in dispersion is less than 200 nm, and which comprises at least 35 wt. % of a silicon dioxide powder, 3 to 35 wt. % of at least one polyol, 20 to 60 wt. % of water, 0 to 10 wt. % of an additive and a substance having an alkaline action in an amount such that a pH of 10<pH?12 is established. It can be prepared by a procedure in which silicon dioxide powder is introduced into water and a polyol in a rotor/stator machine, the pH being less than 5, and the mixture is dispersed until the current uptake of the rotor/stator machine is largely constant, and a substance having an alkaline action is subsequently added in an amount such that a pH of the dispersion of 10<pH?12 results, the substance having an alkaline reaction being added so rapidly that no gel formation takes place.

Abstract: Dispersion comprising hydrophobic pyrogenically prepared silicon dioxide, alcohol and at least one additive which promotes the dispersion and, as additional component, at least one insecticide and/or acaricide. The dispersion can be canned in spray cans and used as insecticide.

Abstract: A dispersion containing aluminum oxide of pyrogenic origin and water, where the aluminum oxide is present in the form of aggregated primary particles with a BET surface area of 20 to 200 m2/g and has a mean, volume-based aggregate diameter in the dispersion of less than 100 nm, and is surface-modified with (i) organophosphonic acids, or salts thereof, and (ii) at least one hydroxycarboxylic acids or salts thereof.

Abstract: Process for preparing an alkaline dispersion of aggregated silicon dioxide particles by dividing a preliminary dispersion within a pH of 3 to 5 into at least two streams, placing these streams under a pressure of at least 50 bar and depressurizing them to a collision point, each via one nozzle, in a grinding chamber, and admixing the dispersion that runs off at the bottom, while still in the grinding chamber, with an alkaline substance in an amount such that the dispersion overall has a pH of more than 7.