Patent ID: 7169198

Claim:
Method for the production of sintered microcrystalline shaped bodies comprising abrasive grains consisting essentially of α-Al 2 O 3 , said bodies have a hardness HV 0.2 greater than or equal to 15 Gpa, a density a median primary crystal size of 0.5 to 0.6 μm greater than or equal to 95% of the theoretical density, and an Al 2 O 3 content of not less than 98 weight percent, comprising the steps of: providing an α-Al 2 O 3 powder with a median particle size d 50 of less than 2 μm; wet grinding the α-Al 2 O 3 powder to a product having maximum particle size d 99 of less than 1 μm; forming a mixture by spray drying the product and subsequently admixing the dried product with at least one binder and at least one solvent; processing the mixture into an extrudable mass; extruding the extrudable mass to an extrudate; processing the extrudate into shaped extruded bodies; and sintering the shaped extruded bodies within a temperature range of 1,300° C. and 1,650° C.