Spherical tungsten disulfide powder
A tungsten disulfide powder comprised of macro-spherical particles of tungsten disulfide having an average particle diameter of from about 5 to about 50 micrometers is prepared by successively treating spray-dried powders of ammonium metatungstate with heat in air and sulfidizing the resultant tungsten trioxide in a carbon disulfide-containing atmosphere at about 750° C. The tungsten disulfide powder may also be formed to have a bimodal particle size distribution of the macro-spherical particles and smaller, dispersed micro- to submicron-sized fine particles.
1. A tungsten disulfide powder comprising substantially spherical particles of tungsten disulfide having an average particle diameter of from about 5 to about 50 micrometers.
2. The tungsten disulfide powder of claim 1 where the average particle diameter is from about 10 to about 25 micrometers.
3. A tungsten disulfide powder comprising substantially spherical particles of tungsten disulfide having an average particle diameter of from about 5 to about 50 micrometers and fine particles of tungsten disulfide having an average particle diameter of from about 0.5 to about 5 micrometers.
4. The tungsten disulfide powder of claim 3 wherein the substantially spherical particles have an average particle diameter of from about 10 to about 25 micrometers.
5. The tungsten disulfide powder of claim 3 wherein the fine particles have an average particle diameter of from about 1 to about 3 micrometers.
6. A tungsten disulfide powder comprising substantially spherical particles of tungsten disulfide having an average particle diameter of from about 5 to about 50 micrometers and wherein at least a portion of the tungsten disulfide particles are hollow.
7. The tungsten disulfide powder of claim 6 wherein the hollow particles have an onion-like structure.
8. The tungsten disulfide powder of claim 6 where the average particle diameter is from about 10 to about 25 micrometers.
9. The tungsten disulfide powder of claim 7 where the average particle diameter is from about 10 to about 25 micrometers.