Patent ID: 7276231

Claim:
A process for making alumina-treated inorganic nanoparticles comprising: (a) forming a slurry of inorganic nanoparticles by mixing the nanoparticles with water; (b) contacting the slurry of inorganic nanoparticles with an amorphous alumina-stabilizing agent; (c) contacting the slurry with a source of alumina to form alumina-treated inorganic nanoparticles; (d) recovering the alumina-treated inorganic nanoparticles by filtering the slurry to form a wet cake; (e) liquefying the wet cake and media milling the liquefied wet cake to form a milled slurry; (f) drying the milled slurry to form a powder; and (g) micronizing the powder to form alumina-treated inorganic nanoparticles in which 5% or less of the particles, based on the volume particle size distribution within a range of 6 nm to 6000 nm, have a diameter greater than 220 nm.