Abrasive material and method
AssigneeNorton Company
InventorsThomas E. Cottringer, Ronald H. van de Merwe, Ralph Bauer, Walter A. Yarbrough
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Abstract
The hardness and microstructure of aluminous abrasives produced from alumina gels are enhanced by introduction of seed material as by wet vibratory milling of the material with alumina media, or by the direct addition of very fine alpha alumina particles in the amount of 1% or less.
Claims12
An alpha alumina polycrystalline body consisting essentially of alpha alumina crystals having a size no greater than about 0.4 microns, said body having a hardness of at least 16 GPa.
Abrasive grain comprising polycrystalline abrasive grits, each of said grits consisting essentially of seeded alpha alumina crystals having a size of less than 1 micron and having a hardness of at least 16 GPa.
Aluminous abrasive grain comprising sintered polycrystalline grits consisting essentially of:
- a. sub-micron crystals of alpha alumina;
- or
- b. a mixture of sub-micron crystals of alpha alumina and spinel;
- or
- c. (a) or (b) with coarser crystals dispersed therein;
- said grits having a density of at least 90% of the theoretical density of alpha alumina.
An alumina-based ceramic body comprising polycrystalline alpha alumina consisting essentially of submicron alpha alumina crystals, said body having a density of at least 95% of theoretical.
Dependencies are inferred from the claim text.