Apparatus and method of treating fine powders
The present invention relates to an apparatus and method for economic treatment of Geldhart class C or larger substrate powders of single or plural metal, ceramic, or polymeric materials. In particular, the present invention is directed to coating such powder via a fluidized CVD or PVD, electroless, electrochemical, or solution chemistry plating process, and provides processes and apparatus for accomplishing same. It is particularly suited to coating with single or plural layers of metal, ceramic, binder, sintering aid, or polymer onto such materials without agglomeration. The coated particles and products made therefrom exhibit novel physical properties that are not limited by classical chemical and thermodynamic constraints.
1. A coating apparatus comprising:
(a) a container for receiving particulate material, said container having a contacting surface;
(b) at least one rack comprising elongated apertures between comb-like teeth, wherein said elongated apertures:
are sufficiently wide to allow the passage of said particulate material;
are parallel to each other and;
have a length that is about 4 to about 30 times their width, said width measured at the midpoint of the length of the teeth
wherein said teeth are:
curved and located along one edge of said rack, and
set at an angle to said contacting surface to apply compression to said particulate material when said particulate material is entrained or squeezed as a result of relative motion between said rack and said contacting surface, wherein said angle is a negative rake angle ranging from about 10 to about 80 degrees, and wherein said compression is sufficient to force the particulate material to flow through said elongated apertures resulting in shear and tensile forces being applied to said particulate material; and
(c) an inlet for introducing particulate material to said container,
wherein said container is in the form of a cylinder or drum, and said rack is at least proximate to the to or to the bottom of said cylinder or drum.
2. The apparatus of claim 1 , wherein said compression provides a flow gradient to said particulate material flowing through said elongated apertures.
3. The apparatus of claim 1 , further comprising a reactant material inlet for introducing reactant materials into said container to coat said particulate material.
4. The apparatus of claim 3 , wherein the particulate material comprises core particles comprising a first metal compound; and said reactant material inlet is sufficient for introducing a second metal compound, different in composition from said first metal compound and having a higher relative fracture toughness.
5. The apparatus of claim 4 , wherein said first metal compound comprises an essentially stoichiometric compound of a nitride, a carbide, a boride, an oxide, a sulfide, or a silicide.
6. The apparatus claim 4 , wherein said first metal compound comprises at least one of TiN, TiCN, TiC, ZrC, ZrN, VO, VN, cBN, Al2O3, Si3N4, SiB6, SiAlCB, W2B5, AlN, AlMgB14, MoS2, MoSi2, Mo2B5, Mo2B, or diamond.
7. The apparatus of claim 4 , wherein said second metal compound comprises WC or W 2 C.
8. The apparatus of claim 1 , wherein said shear and tensile forces are in an amount sufficient to break up agglomerates of said particulate material.
9. The apparatus of claim 1 , wherein said contacting surface comprises the inside or outside of said cylinder or drum.
10. The apparatus of claim 9 , wherein said contacting surface of said cylinder or drum has a diameter approximately 0.25 to 25 times its width.
11. The apparatus of claim 1 , further comprising a guide for said particulate material that causes said particulate material to recirculate or move laterally within said container.
12. The apparatus of claim 9 , wherein said guide is at least proximate to the bottom of said cylinder or drum.
13. The apparatus of claim 1 , said rack being comprised at least one of: stainless steel, austenitic steel, ferritic-austenitic steels, superalloy steel, refractory metal, ceramic, quartz, carbon, or refractory-coated metallic alloys.