Minnesota Mining and Manufacturing Company

Larry D Monroe

Thomas Edward Wood

William P Wood

Dwight D Erickson

David M Wilson

Method for making alpha alumina-based ceramic material (e.g., abrasive grain and fibers) from a hydrothermally treated boehmite dispersion comprising colloidal silica.

Method for making ceramic materials from boehmite

Methods for making abrasive articles (e.g., coated abrasives, bonded wheels, and three dimensional, low density abrasives) comprising crystalline ceramic, alpha alumina-based abrasive grain.

Method for making an abrasive article

A method of making an alpha alumina-based ceramic abrasive grain comprising, on a theoretical oxide basis, Al.sub.2 O.sub.3, Fe.sub.2 O.sub.3, and SiO.sub.2. The abrasive grain has a surface roughness height of greater than about 200 nanometers and a density of greater than about 3.50 g/cm.sup.3. Preferably, the alpha alumina-based ceramic abrasive grain has alpha alumina crystallites having an average crystallite size of less than about 0.5 micrometer (more preferably, less than about 0.3 micrometer). The presence of the SiO.sub.2 in combination with Fe.sub.2 O.sub.3 increases the amount of transgranular fracture of the abrasive grain, reduces the alpha alumina crystallite growth during sintering of the abrasive grain, dilates at least one of the unit cell dimensions of the abrasive grain, and generally improves the grinding performance of the abrasive grain.

Method of making alpha alumina-based abrasive grain containing silica

An alpha alumina-based ceramic abrasive grain comprising, on a theoretical oxide basis, Al.sub.2 O.sub.3, Fe.sub.2 O.sub.3, and SiO.sub.2. The abrasive grain has a surface roughness height of greater than about 200 nanometers and a density of greater than about 3.50 g/cm.sup.3. Preferably, the alpha alumina-based ceramic abrasive grain has alpha alumina crystallites having an average crystallite size of less than about 0.5 micrometer (more preferably, less than about 0.3 micrometer). The presence of the SiO.sub.2 in combination with Fe.sub.2 O.sub.3 increases the amount of transgranular fracture of the abrasive grain, reduces the alpha alumina crystallite growth during sintering of the abrasive grain, dilates at least one of the unit cell dimensions of the abrasive grain, and generally improves the grinding performance of the abrasive grain.

Alpha alumina-based abrasive grain containing silica and iron oxide

Crystalline ceramic, alpha alumina-based abrasive grain and a method of making the same. The abrasive grain can be incorporated into abrasive products such as coated abrasives, bonded wheels, and three dimensional, low density abrasives.

Abrasive grain

Ceramic abrasive grits comprising alpha alumina and at least about 0.5 percent by weight rare earth metal oxide are prepared by combining alumina hydrate and rare earth metal oxide or its precursors to produce a blend, drying the blend to produce a dried solid, crushing the dried solid to produce grits, calcining the dried grits to substantially remove bound volatile materials, and firing the grits to produce a ceramic material. The rare earth metal is selected from the group consisting of praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, cerium, dysprosium, erbium, and mixtures of one or more rare earth metal.

Abrasive grits formed of ceramic containing oxides of aluminum and rare

Ceramic abrasive grits comprising alpha alumina and at least about 0.5 percent by weight yttria are prepared by mixing an aqueous dispersion of alpha alumina monohydrate and yttrium compound, gelling the resultant mixture, drying the gel to produce a dried solid, crushing the dried material to produce grits, calcining the dried grits to substantially remove bound volatile materials, and firing the grits to produce a ceramic material. The yttrium for the most part is in the form of a yttrium aluminum garnet. Abrasive products comprising the abrasive grits are also claimed as is a method of grinding a workpiece with such abrasive products.

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Eagan, MN, United States of America

Larry D Monroe