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.
REFERENCE TO PRIOR APPLICATIONS
This is a continuation of application Ser. No. 08/705,390, filed Aug. 30, 1996 now U.S. Pat. No. 5,660,604, which is a continuation of application Ser. No. 08/474,730, filed Jun. 7, 1995, now U.S. Pat. No. 5,551,964, which is a continuation of application Ser. No. 08/237,400 filed May 3, 1994, now U.S. Pat. No. 5,431,705, which is a continuation of application Ser. No. 07/976,893 filed Nov. 16, 1992, now U.S. Pat. No. 5,312,789, which is a continuation of application Ser. No. 07/799,867 filed Nov. 27, 1991, now U.S. Pat. No. 5,164,348, which is a continuation of application Ser. No. 07/645,349, filed Jan. 24, 1991, abandoned, which is a continuation-in-part of application Ser. No. 07/054,440, filed May 27, 1987, abandoned.
An optical polishing tool comprises alpha alumina and ceria components in relative weight proportions of from 30:70 to 70:30 dispersed in a resin binder. Particularly preferred are coated abrasives. Such coated abrasives produce an improved optical polishing performance.
A process for converting carbon monoxide and water in a reformate stream into carbon dioxide and hydrogen comprising: generating a reformate by reacting a hydrocarbon via partial oxidation, steam reforming, or both, including autothermal reforming; and promoting a water gas shift in the reformate in the presence of a platinum group metal selected from the group consisting of platinum, palladium, iridium, osmium, rhodium and mixtures thereof, supported on zirconium oxide. The platinum group metal advantageously may be supported directly on a monolithic substrate composed of zirconium oxide.
Alpha alumina-based abrasive grain and method of making the same. The abrasive grain can be incorporated into abrasive products such as coated abrasives, bonded abrasives, non-woven abrasives, and abrasive brushes.
Sintered alpha alumina-based abrasive particles comprising alpha alumina, Gd.sub.2 O.sub.3, and ZnO, and methods of making the same. The abrasive particles can be incorporated, for example, into a variety of abrasive articles, including bonded abrasives, coated abrasives, nonwoven abrasives, and abrasive brushes.
Alpha alumina-based abrasive grain. The abrasive grain can be incorporated into abrasive products such as coated abrasives, bonded abrasives, non-woven abrasives, and abrasive brushes.
