| 摘要 |
The invention concerns an abrasive grain based on electromelted alumina consisting of crystals with a hexagonal structure, of size less than 100 mu m, and preferably less than 30 mu m, and more preferably less than 5 mu m, with density higher than 97 %, preferably 98 %, of the theoretical density of alumina, and a Knoop hardness higher than 2000. The invention also concerns a method for making abrasive grains based on alumina consisting in melting alumina, casting it at a constant flow rate less than 80 kg/mn, and cooling it by dispersing the melted alumina in fine droplets to obtain articles with size less than 1 mm. Said dispersion is preferably performed by ultrasound-assisted spraying, at a frequency ranging between 15 and 50 MHz. The inventive grains are used in particular for making grindstones.
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