Apparatus and method of treating fine powders

Abstract

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.

What is claimed is:  
     
         1 . An 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, said teeth being set at an angle to said contacting surface to apply non-uniform 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 non-uniform 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.    
     
     
         2 . The apparatus of  claim 1 , wherein said non-uniform 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 1 , wherein said shear and tensile forces are in an amount sufficient to break up agglomerates of said particulate material.  
     
     
         5 . The apparatus of  claim 1 , wherein said angle is a negative rake angle ranging from about 10 to about 80 degrees.  
     
     
         6 . The apparatus of  claim 1 , wherein said contacting surface comprises the inside or outside of a cylinder or drum, a disk, or a belt.  
     
     
         7 . The apparatus of  claim 6 , wherein said contacting surface of said cylinder or drum has a diameter approximately 0.25 to 25 times its width.  
     
     
         8 . The apparatus of  claim 6 , wherein said teeth are curved and located along one edge of said rack.  
     
     
         9 . 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.  
     
     
         10 . The apparatus of  claim 9 , said container being in the form of a cylinder or drum, said rack being at least proximate to the top of said cylinder or drum and said guide being at least proximate to the bottom of said cylinder or drum.  
     
     
         11 . The apparatus of  claim 1 , wherein the width of said elongated apertures between said comb-like teeth are about the same size as the width of the teeth measured at the midpoint of the length of the teeth, the width of said apertures increasing along the length of the teeth from the edge of said rack opposite said teeth.  
     
     
         12 . The apparatus of  claim 11 , wherein the length of the teeth ranges from about 4 to about 30 times their width, said width measured at the midpoint of the length of the teeth, the closed end of said apertures being rounded.  
     
     
         13 . The apparatus of  claim 1 , wherein said elongated apertures between said comb-like teeth are larger than the width of the teeth, said teeth being parallel to each other and having a length that is about 4 to about 30 times their width, said width measured at the midpoint of the length of the teeth, the closed end of said apertures being rounded.  
     
     
         14 . 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.  
     
     
         15 . A method of treating particulate material, said method comprising: 
 (a) introducing said particulate material to a container having a contacting surface and a contacting member within said container, said contacting member having a structural support portion and a comb-like portion with at least one elongated aperture therethrough;    (b) applying non-uniform compression to said particulate material by forcing said particulate material through at least one elongated aperture within said comb-like portion of said contacting member by the relative motion between said contacting member and said contacting surface of said container, said non-uniform compression being sufficient to force the particulate material to flow through said elongated apertures resulting in shear and tensile forces being applied to said particulate material;    (c) adjusting relative motion between said surface and said contacting member such that the particulate material passes through at least one reaction zone within said container;    (d) applying additional non-uniform compression to said particulate material by forcing said particulate material between said structural support portion of said contacting member by the relative motion between said contacting member and said contacting surface of said container, said additional non-uniform compression being sufficient to apply shear and tensile forces to said particulate material, the amount of said additional non-uniform compression being determined by (i) the angle between said contacting surface and said contacting member, (ii) the coefficient of friction of said contacting surface and said contacting member, and (iii) the velocity of the relative motion between said contacting surface and said contacting member; and    (e) retaining said particulate material within said container a sufficient time and under sufficient conditions to treat said particulate material.    
     
     
         16 . A method of  claim 15 , wherein said angle provides compression, shear, or tensile forces to said particulate material in an amount sufficient to break up agglomerates.  
     
     
         17 . The method of  claim 15 , wherein said method includes coating said particulate material.  
     
     
         18 . The method of  claim 17 , wherein the coating of said particulate material forms coated particles comprising: 
 core particles comprising a first metal compound; and    at least one layer on a majority of said core particles, said layer comprising a second metal compound, different in composition from said first metal compound and having a higher relative fracture toughness.    
     
     
         19 . The method of  claim 18 , wherein said first metal compound comprises an essentially stoichiometric compound of a nitride, a carbide, a boride, an oxide, a sulfide, or a silicide.  
     
     
         20 . The method of  claim 18 , wherein said first metal compound comprises at least one of TiN, TiCN, TiC, ZrC, ZrN, VC, VN, cBN, Al 2 O 3 , Si 3 N 4 , SiB 6 , SiAICB, W 2 B 5 , AIN, AlMgB 14 , MoS 2 , MoSi 2 , MO 2 B 5 , Mo 2 B, or diamond.  
     
     
         21 . The method of  claim 18 , wherein said second metal compound comprises WC or W 2 C.  
     
     
         22 . The method of  claim 17 , wherein the coating of said particulate material forms coated particles comprising: 
 a plurality of core particles consisting essentially of a material selected from the group consisting of cubic boron nitride and diamond;    an intermediate layer on a majority of said core particles, said intermediate layer consisting essentially of WC, said intermediate layer having a thickness in the range of from 5% to 25% of the diameter of said core particles; and    an outer layer comprising cobalt or nickel overlaying said intermediate layer, the combination of said core particles, said intermediate layer, and said outer layer forming said coated particles.    
     
     
         23 . The method of  claim 17 , wherein the coating of said particulate material forms coated particles comprising: 
 a plurality of core particles consisting essentially of a material selected from the group consisting of cubic boron nitride and diamond;    an intermediate layer on a majority of each of said core particles, said intermediate layer comprising tool steel, glassy and devitrified nanosteel alloys, silicon nitride, or tantalum carbide, said intermediate layer having a thickness in the range of from 5% to 25% of the diameter of said core particles; and    an outer layer comprising cobalt or nickel overlaying said intermediate layer, the combination of said core particles, said intermediate layer, and said outer layer forming said coated particles.    
     
     
         24 . The method of  claim 17 , wherein the coating of said particulate material forms coated particles, the majority of said coated particles having: 
 core particles consisting essentially of a first metal compound having the formula M a X b , where    M represents one or more metals selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, aluminum, magnesium, copper, and silicon,    X represents one or more elements selected from the group consisting of nitrogen, carbon, boron, sulfur, and oxygen,    a and b are numbers greater than zero up to and including fourteen; and    a layer on a majority of each of said core particles, said layer comprising a second metal or metal compound, different in composition from said first metal compound and having a higher relative fracture toughness than said first metal compound, said second metal or metal compound being capable of bonding with said first metal compound and being capable of bonding with a metal selected from the group consisting of iron, cobalt, nickel, copper, titanium, aluminum, magnesium, lithium, beryllium, silver, gold, or platinum.    
     
     
         25 . The method of  claim 17 , including the step of introducing a vapor phase stream comprising at least one of a reactive gas and an inert gas to said container.  
     
     
         26 . The method of  claim 25 , wherein said reactive and inert gases are chosen from nitrogen, hydrogen, argon, or oxygen.  
     
     
         27 . The method of  claim 25 , wherein said reactive gas is selected from the group consisting of hydrogen, oxygen, a carburizing gas, and a boronizing gas.  
     
     
         28 . A method of  claim 25 , further comprising the steps of filtering the vapor phase stream and recirculating the filtered vapor phase stream to said container.  
     
     
         29 . A method of  claim 25 , further comprising filtering the vapor phase stream and recirculating both the filtered vapor phase stream and the particulate material to said container.  
     
     
         30 . The method of  claim 29 , wherein recirculating the particulate material is accomplished by a feed screw.  
     
     
         31 . The method of  claim 30 , wherein said feed screw has an inlet end and a discharge end, and is designed with a progressively-increasing pitch from said inlet end to said discharge end.  
     
     
         32 . The method of  claim 25 , wherein the vapor phase stream is preheated prior to its introduction into said container.  
     
     
         33 . A method of  claim 25 , wherein the particulate material is preheated prior to its introduction into said container.  
     
     
         34 . A method of  claim 25 , wherein said reactive gas and said inlet gas are introduced by use of ceramic or metallic frit.  
     
     
         35 . The method of  claim 17 , further comprising a step of neutralizing waste reactants by an exhaust trap system.  
     
     
         36 . The method of  claim 17 , said method providing a uniform coating thickness across a particle size distribution for said particulate material, wherein said particle size distribution ranges from about 1.0 nanometers to about 150 microns in average diameter.  
     
     
         37 . A method of  claim 17 , wherein the method is used to coat Geldart Class C particulate matter with a uniform coating thickness.  
     
     
         38 . The method of  claim 18 , wherein said at least one layer comprises one or more layers of metal, ceramic, binder, sintering aid, or polymeric material.  
     
     
         39 . The method of  claim 17 , wherein said coating step comprises chemical vapor or physical vapor deposition.  
     
     
         40 . The method of  claim 17 , wherein said coating step comprises plasma deposition.  
     
     
         41 . The method of  claim 17 , wherein said coating step comprises electrochemical, electroless, or solution chemistry deposition.  
     
     
         42 . The method of  claim 17 , wherein said structural support portion is planar.  
     
     
         43 . The method of  claim 17 , wherein said structural support portion is non-planar.  
     
     
         44 . The method of  claim 17 , wherein said particulate material comprises one or more particles of metal, ceramic, refractory alloy, or polymeric material.