Process of producing spherical powders of metal, and alloys and composites thereof

A method for producing spherical metal powder particles from a metal or metal alloy starting material, the method comprising:

• (a) preparing a slurry comprising a pre-alloyed metal powder having an average particle size D50 of about 0.01 microns to about 10 microns, an organic binder, and a solvent;
• (b) spray drying the slurry to produce spherical agglomerates having an average particle size D50 of about 5 to about 150 microns;
• (c) debinding the spherical agglomerates;
• and
• (d) heating the debound agglomerates to a temperature between a solidus temperature and a liquidus temperature of the metal or metal alloy starting material to cause partial melting and formation of a liquid phase within each debound agglomerate, whereby the debound agglomerates are densified to a density of about 95% to about 100% of theoretical density by liquid phase sintering at a granule level without a subsequent plasma spheroidization step,
• and wherein the heating is performed in a fluidized bed furnace, a rotating tube furnace, or on a non-wetting substrate selected from the group consisting of boron nitride-coated alumina and yttria-stabilized zirconia.

A method for producing spherical metal powder particles from a metal or metal alloy starting material, the method comprising:

• (a) preparing a slurry comprising a metal or metal alloy powder having an average particle size D50 of about 0.01 microns to about 10 microns, an organic binder, and a solvent;
• (b) spray drying the slurry to produce spherical agglomerates having an average particle size D50 of about 5 to about 150 microns;
• (c) debinding the spherical agglomerates;
• and
• (d) feeding the debound agglomerates directly into a DC plasma torch without a prior sintering step, wherein the DC plasma simultaneously densifies and spheroidizes the debound agglomerates to a density of about 99% to about 100% of theoretical density.

A method for producing spherical metal powder particles from metal oxide starting materials, the method comprising:

• (a) preparing a slurry comprising a metal oxide powder having an average particle size D50 of about 0.01 microns to about 10 microns, an organic binder, and a solvent;
• (b) spray drying the slurry to produce spherical oxide agglomerates;
• (c) debinding the spherical oxide agglomerates;
• (d) sintering the debound spherical oxide agglomerates under an inert or hydrogen-containing atmosphere,
• (e) reducing the debound oxide agglomerates to metallic form via hydrogen reduction or metallothermic reduction, wherein
• step (e) is performed simultaneously with step (d) under a hydrogen, hydrogen-containing, or a forming gas atmosphere such that sintering consolidation and oxide reduction occur concurrently in a single combined thermal step to form a reduced metal powder;
• or
• step (e) is performed as a separate step after step (d) to form the reduced metal powder;
• and
• (f) subjecting the reduced metal powder to DC plasma spheroidization to restore sphericity and produce spherical metal powder particles having a density of about 99% to about 100% of theoretical density.