Abrasive grits formed of ceramic, impregnation method of making the same and products made therewith

Claim 1

Ceramic abrasive grits comprising alpha alumina characterized by at least one modifying additive metal selected from the group consisting of zirconium, hafnium, cobalt, nickel, zinc, magnesium, yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, cerium, dysprosium, erbium, and combinations of two or more of such metals, wherein the concentration of said modifying additive metal is greater at or near the surface of said grit than at the interior of said grit.

Claim 8

A method of making ceramic abrasive grits, said method comprising the steps of: (1) preparing a sol of alumina hydrate; (2) drying the sol to form a dried porous solid comprised of the dried sol; (3) crushing the dried porous solid to produce particles; (4) calcining the dried particles to substantially remove water of hydration and convert the alumina hydrate to an alumna form which is insoluble in said liquid vehicle; (5) drying the impregnated particles; (6) calcining the dried impregnated particles to substantially remove bound volatile materials; (7) firing the grits to produce ceramic abrasive grits characterized by; (8) preparing a homogeneous mixture of an additive metal oxide or its precursor in a liquid vehicle; and (9) impregnating the mixture of step (8) into the calcined particles to achieve an average concentration of modifying additive in the resultant ceramic after firing of at least about 0.5% by weight on a fired solids basis;

Claim 9

A method of making ceramic abrasive grits, said method comprising the steps of: (1) preparing a sol of alumina hydrate; (2) drying the sol to form a dried porous solid comprised of the dried sol; (3) crushing the dried porous solid to produce particles; (4) calcining the dried particles to substantially remove water of hydration and convert the alumina hydrate to an alumna form which is insoluble in said liquid vehicle; (5) drying the impregnated particles; (6) calcining the dried impregnated particles to substantially remove bound volatile materials; (7) firing the grits to produce ceramic abrasive grits characterized by; (8) preparing a homogeneous mixture of an additive metal oxide or its precursor in a liquid vehicle; and (9) impregnating the mixture of step (8) into the calcined particles to achieve an average concentration of modifying additive in the resultant ceramic after firing of at least about 0.5% by weight on a fired solids basis;