摘要:
Described is a method of producing spherical particles made from inorganic oxides by sol/gel conversion in which a sol is sprayed upwards from below into a reaction zone containing a reactant gas in such a way that the sol does not split up into individual droplets until immediately before or as it enters the reaction zone, and the droplets thus formed fly through the reaction zone along a curved trajectory during which they are presolidified, the presolidified droplets being caught in a trap. Also described are spherical particles made from inorganic oxides with a narrow pore-diameter distribution and a resistance to wear which are suitable for use as catalysts, catalyst supports, adsorbants, drying agents or ion-exchange materials.
摘要:
Böhmit ist im allgemeinen von gelatinöser Natur, wenn die Suspension in wässrigem Medium hergestellt wird, und damit für viele Anwendung nicht mehr nutzbar. Nach dem neuen Verfahren soll aus relativ billigen Grob-Al(OH)₃-Partikeln feinverteilter Böhmit hergestellt werden, der sich leicht in wässrige Dispersionen, die beim Stehen kein Gel bilden, umwandeln lässt. Hierzu wird grobkörniges Al(OH)₃ auf eine Temperatur oberhalb 350° C erhitzt, das aktivierte Material mit erwärmter alkalischer oder saurer Lösung behandelt, um feinverteiltes Böhmit freizusetzen. Das Produkt hat eine spezifische Oberfläche von 30-70 m²/g, eine Partikelgröße von 0,02 - 50 um, einen Na₂O-gehalt von 0,01-0,10 Gew.% und lässt sich leicht in wässrigem Medium dispergieren. Die resultierenden Suspensionen sind stabil und gelieren nicht. Böhmitteilchen finden Anwendung in der Keramik-, Feuerfest, Papier- und Textilindustrie.
摘要:
Ceramic abrasive grits are formed by an impregnation process that involves preparing an alumina hydrate sol, drying the sol to form a porous solid, crushing the solid to produce particles, calcining the dried particles, preparing a mixture of an additive metal oxide or its precursor in a liquid vehicle, impregnating the mixture into the calcined particles, drying the impregnated particles, calcining the dried impregnated particles, and firing the particles to produce ceramic abrasive grits. The concentration of the modifying additive metal is greater at or near the surface of the grit than at the interior of the grit.
摘要:
Füllstoff auf Basis von Aluminiumhydroxid (Al 2 O 3 x H 2 O, x = 1 - 3) mit einer endothermen Zersetzungswärme >900 Kj/kg, der aus Hydrargillitkörnern besteht, deren Krystallite an der Oberfläche entwässert sind, und der insbesondere weiß-pigmentierende Eigenschaften aufweist.
摘要:
Stable alkaline sols of anionic alumina hydrate may be made by calcining alumina trihydrate and milling the monohydrate produced under alkaline conditions. Alkaline sols containing both anionic alumina hydrate and anionic colloidal silica may be used for bonding refractory bodies.
摘要:
A high-purity microparticle alumina powder is provided which has excellent slurry properties and sintering properties, excellent fluidity and formability, and furthermore has excellent dielectric properties in the highfrequency region. In this high-purity microparticle alumina powder, the 50% particle diameter (D50) in the volume particle size distribution and the BET specific surface area (SBET) satisfy the relations represented by the formula D50 ≤ 0.20 µm and the formula D50 × SBET ≤ 2.0 × 10-6 m3/g, and the content of sodium (Na), silicon (Si), iron (Fe) and calcium (Ca) is each less than or equal to 10 ppm.
摘要:
The present invention relates to formulations containing alumina flakes having a defined thickness and particle size distribution and to their use as varnishes, paints, automotive coatings, printing inks, masterbatches, plastics and cosmetic formulations