Abstract: A process for forming a ceramic alumina-based abrasive grain from a sol gel which contains aluminum oxide monohydrate, a dissolved metal containing sintering aid and sufficient sodium and/or calcium compound to provide in the ceramic from above about 0.05 to about 1.8 weight percent sodium plus calcium, provided that the weight percent calcium is from 0 to about 1.8 and the weight percent sodium is from 0 to about 0.4. The high sodium and calcium is permitted due to rapid heating of the sol gel after drying through a temperature range of from below about 800.degree. C. to above about 1200.degree. C., prior to sintering the dried gel at a temperature above 1200.degree. C. A grain made by the process and coated, bonded and non-woven abrasive articles comprising the grain.

Abstract: A method of electrically separating differing shapes of abrasive grain materials by imposing a high voltage corona induction charge to free-falling abrasive particles, polarization thereof and attraction thereof to a high voltage oppositely charged electrical field is disclosed, along with apparatus by which the method is practiced and the characteristics of shape of the particles of abrasive grain materials so separated.

Abstract: An abrasive grain comprising about 20 to about 50% by weight of zirconia; reduced titania in an amount on analysis expressed as titanium dioxide of 1.5 to about 10% by weight; total carbon in an amount of 0.03 to about 0.5% by weight; impurities, if any, in a total amount on analysis expressed as the oxides of not greater than 3% by weight; and a balance of alumina. The microstructure of the abrasive grain comprises primary alumina or zirconia crystals embedded in a supporting alumina-zirconia eutectic matrix. The grain may be produced by combining and melting the alumina and zirconia; adding titania and carbon (excess carbon being required); melting and reducing the titania under reducing furnace conditions; and solidifying the melt in under three minutes by means of a suitable heat sink material. The abrasive grain has a high proportion of tetragonal zirconia and may be used to produce coated abrasive products or bonded abrasive products.

Abstract: Method of automatically separating and cleaning silicon carbide furnace materials using magnetic separation techniques. In the method of the invention, crushed or particulate silicon carbide furnace materials are mixed with a magnetic powder. The lower grade silicon carbide particles are then separated from the first grade silicon carbide crystals using magnetic separation. Recoveries of at least 75% of the first grade silicon carbide are possible using the method of the invention. This method is also useful for the beneficiation of ores, minerals, or man-made materials.

Abstract: Method of automatically separating and cleaning silicon carbide furnace materials using magnetic separation techniques. In the method of the invention, crushed or particulate silicon carbide furnace materials are mixed with a magnetic powder. The lower grade silicon carbide particles are then separated from the first grade silicon carbide crystals using magnetic separation means. Recoveries of at least 75% of the first grade silicon carbide are possible using the method of the invention. This method is also useful for the beneficiation of ores, minerals, or man-made materials.

Abstract: Method of producing silicon carbide and of automatically separating a high grade fraction thereof using magnetic separation techniques. In the method of the invention, a silicon source, a carbon source and a ferromagnetic element source are admixed and the admixture is heated from the center outward to form a cylinder containing silicon carbide with a center to exterior temperature gradient. The ferromagnetic element migrates from the hotter center to the cooler exterior portions of the cylinder. The cylinder is cooled and crushed. The lower grade silicon carbide particles are then separated from the high grade silicon carbide crystals using magnetic separation means.

Abstract: A fused abrasive grain, useful for inclusion in coated abrasives and bonded abrasives, consists essentially of alumina; titanium oxide containing from about 0.42 to about 0.84% titaniun, by weight of the abrasive grain, present as a reduced titanium oxide having an average oxidation state lower than in Ti.sub.2 O.sub.3 ; from about 0.05 to about 0.3% by weight carbon; from about 0.02 to about 0.1% by weight Na.sub.2 O; and from 0 to about 0.1% by weight total of calcium and silicon oxides. The grain before roasting has a gain on ignition of from about 0.4 to about 0.7% by weight, and is produced in an electric furnace by fusing high-purity titania, alumina containing Na.sub.2 O as the only significant oxide impurity, and carbon, followed by crushing and roasting the fused grain.

Abstract: A fused abrasive grain, useful for inclusion in coated abrasives and bonded abrasives, consists essentially of alumina; titanium oxide containing from about 0.42 to about 0.84% titanium, by weight of the abrasive grain, present as a reduced titanium oxide having an average oxidation state lower than in Ti.sub.2 O.sub.3 ; from about 0.05 to about 0.3% by weight carbon; from about 0.02 to about 0.1% by weight Na.sub.2 O; and from 0 to about 0.1% by weight total of calcium and silicon oxides. The grain before roasting has a gain on ignition of from about 0.4 to about 0.7% by weight, and is produced in an electric furnace by fusing high-purity titania, alumina containing Na.sub.2 O as the only significant oxide impurity, and carbon, followed by crushing and roasting the fused grain.

Abstract: A fused abrasive grain, useful for inclusion in coated abrasives and bonded abrasives, consists essentially of alumina; titanium oxide containing from about 0.42 to about 0.84% titanium, by weight of the abrasive grain, present as a reduced titanium oxide having an average oxidation state lower than in Ti.sub.2 O.sub.3 ; from about 0.05 to about 0.3% by weight carbon; from about 0.02 to about 0.1% by weight Na.sub.2 O; and from 0 to about 0.1% by weight total of calcium and silicon oxides. The grain before roasting has a gain on ignition of from about 0.4 to about 0.7% by weight, and is produced in an electric furnace by fusing high-purity titania, alumina containing Na.sub.2 O as the only significant oxide impurity, and carbon, followed by crushing and roasting the fused grain.

Abstract: A fused abrasive grain, useful for inclusion in coated abrasives and bonded abrasives, consists essentially of alumina; titanium oxide containing from about 0.42 to about 0.84% titaniun, by weight of the abrasive grain, present as a reduced titanium oxide having an average oxidation state lower than in Ti.sub.2 O.sub.3 ; from about 0.05 to about 0.3% by weight carbon; from about 0.02 to about 0.1% by weight Na.sub.2 O; and from 0 to about 0.1% by weight total of calcium and silicon oxides. The grain before roasting has a gain on ignition of from about 0.4 to about 0.7% by weight, and is produced in an electric furnace by fusing high-purity titania, alumina containing Na.sub.2 O as the only significant oxide impurity, and carbon, followed by crushing and roasting the fused grain.