| abstract |
Very rapid crystallization of eutectic and neareutectic molten mixtures of aluminum oxide and zirconium oxide, followed by crushing of the solidified melt, results in abrasive grits of very high strength combined with highly desirable microfracture properties. The zirconium oxide in the material is in the form of rods (or platelets) which, on the average, are less than 3000 angstroms in diameter, and preferably at least 25%, by weight, of the zirconium oxide is in the tetragonal crystal form. The solidified melt is made up of cells or colonies typically 40 microns or less across their width. Groups of cells having identical orientation of microstructure form grains which typically include from 2 to 100 or more cells or colonies. In crushing, the material fractures along grain boundaries and cell boundaries. Grinding improvement in excess of 100% of prior art standards is shown in tests of coated abrasive products employing the crushed abrasive material in typical applications and substantial improvement in bonded abrasive products. |