Patent ID: 8313725

Claim:
An in-situ method for nanomixing magnesium aluminate spinel nanoparticles with a uniformly distributed controlled concentration of nanoparticles of an inorganic sintering aid to produce ready-to-sinter spinel powder consisting essentially of a perfectly dispersed discrete mix of said spinel nanoparticles and said sintering aid nanoparticles and being essentially free of sintering aid-coated spine nanoparticles, said method comprising the steps of: (a) mixing said spinel nanoparticles with an aqueous solution of said inorganic sintering aid to form a spinel dispersion; (b) decreasing the solubility limit of said inorganic sintering aid in said spinel dispersion to a point sufficiently low so as to induce precipitation of nanoparticles of said inorganic sintering aid out of solution and into a mixed dispersion with said spinel nanoparticles; (c) separating from said mixed dispersion an in-situ formed nanomixture of said spinel nanoparticles and said sintering aid nanoparticles; (d) drying the spinel-sintering aid nanomixture; and (e) deagglomerating the dried spinel-sintering aid nanomixture; wherein the concentration of said inorganic sintering aid in said aqueous solution, the relative proportions of aqueous solution and spinel nanoparticles employed in forming said spinel dispersion, the extent of solubility limit decrease in the precipitation step, and the retention time of the precipitation step are all selected and coordinated so as to provide the deagglomerated dried spinel-sintering aid nanomixture with said uniformly distributed controlled concentration of inorganic sintering aid nanoparticles.