Methods and systems for slurry coating

Abstract

The present disclosure provides systems and methods that employ slurries to form layers adjacent to substrates. Such layers can include, for example, one or more of iron, chromium, nickel, silicon, vanadium, titanium, boron, tungsten, aluminum, molybdenum, cobalt, manganese, zirconium, and niobium, oxides thereof, nitrides thereof, sulfides thereof, or combinations thereof. In some examples, such layers are stainless steel layers.

1 . A slurry for forming at least one layer comprising at least one elemental metal adjacent to a substrate, comprising:
 (a) a solvent;   (b) an alloying agent, wherein said alloying agent comprises said at least one elemental metal, and wherein said alloying agent is configured to diffuse into said substrate;   (c) a halide activator that facilitates diffusion of said at least one elemental metal to said substrate; and   (d) an inert species that aids in dispersing said alloying agent in said solvent, wherein said inert species has a particle size that is less than or equal to about 200 mesh.   
     
     
         2 . The slurry of  claim 1 , wherein a particle size of said alloying agent is greater than said particle size of said inert species. 
     
     
         3 . The slurry of  claim 1 , wherein said particle size of said alloying agent is less than about 140 mesh. 
     
     
         4 . The slurry of  claim 1 , wherein said alloying agent is selected from the group consisting of iron, chromium, nickel, silicon, vanadium, titanium, boron, tungsten, aluminum, molybdenum, cobalt, manganese, zirconium, niobium and combinations thereof. 
     
     
         5 . The slurry of  claim 1 , wherein said at least one elemental metal is selected from the group consisting of chromium, nickel, aluminum, silicon, vanadium, titanium, boron, tungsten, aluminum, molybdenum, cobalt, manganese, zirconium, niobium and combinations thereof. 
     
     
         6 . The slurry of  claim 1 , wherein said halide activator is selected from the group consisting of magnesium chloride (MgCl 2 ), iron (II) chloride (FeCl 2 ), calcium chloride (CaCl 2 ), zirconium (IV) chloride (ZrCl 4 ), titanium (IV) chloride (TiCl 4 ), niobium (V) chloride (NbCl 5 ), titanium (III) chloride (TiCl 3 ), silicon tetrachloride (SiCl 4 ), vanadium (III) chloride (VCl 3 ), chromium (III) chloride (CrCl 3 ), trichlorosilane (SiHCl 3 ), manganese (II) chloride (MnCl 2 ), chromium (II) chloride (CrCl 2 ), cobalt (II) chloride (CoCl 2 ), copper (II) chloride (CuCl 2 ), nickel (II) chloride (NiCl 2 ), vanadium (II) chloride (VCl 2 ), ammonium chloride (NH 4 Cl), sodium chloride (NaCl), potassium chloride (KCl), molybdenum sulfide (MoS), manganese sulfide (MnS), iron disulfide (FeS 2 ), chromium sulfide (CrS), iron sulfide (FeS), copper sulfide (CuS), nickel sulfide (NiS), and combinations thereof. 
     
     
         7 . The slurry of  claim 1 , wherein said halide activator is hydrated. 
     
     
         8 . The slurry of  claim 1 , wherein a molar ratio of a halide of said halide activator to said at least one elemental metal is at most about 10:1. 
     
     
         9 . A method for producing a slurry, comprising:
 (a) providing an alloying agent, a halide activator, a solvent, and an inert species to a vessel to provide a mixture, wherein a particle size of said inert species is less than or equal to about 200 mesh; and   (b) subjecting said mixture having said alloying agent, halide activator, solvent and inert species to mixing, thereby producing said slurry.   
     
     
         10 . The method of  claim 9 , wherein said mixing occurs at a shear rate from about 1 s −1  to 10000 s −1 . 
     
     
         11 . The method of  claim 9 , wherein said halide activator is selected from the group consisting of magnesium chloride (MgCl 2 ), iron (II) chloride (FeCl 2 ), calcium chloride (CaCl 2 ), zirconium (IV) chloride (ZrCl 4 ), titanium (IV) chloride (TiCl 4 ), niobium (V) chloride (NbCl 5 ), titanium (III) chloride (TiCl 3 ), silicon tetrachloride (SiCl 4 ), vanadium (III) chloride (VCl 3 ), chromium (III) chloride (CrCl 3 ), trichlorosilance (SiHCl3), manganese (II) chloride (MnCl 2 ), chromium (II) chloride (CrCl 2 ), cobalt (II) chloride (CoCl 2 ), copper (II) chloride (CuCl 2 ), nickel (II) chloride (NiCl 2 ), vanadium (II) chloride (VCl 2 ), ammonium chloride (NH 4 Cl), sodium chloride (NaCl), potassium chloride (KCl), molybdenum sulfide (MoS), manganese sulfide (MnS), iron disulfide (FeS 2 ), chromium sulfide (CrS), iron sulfide (FeS), copper sulfide (CuS), nickel sulfide (NiS) and combinations thereof. 
     
     
         12 . The method of  claim 9 , wherein said halide activator is hydrated. 
     
     
         13 . The method of  claim 12 , wherein said halide activator is selected from the group consisting of iron chloride tetrahydrate (FeCl 2 .4H 2 O), iron chloride hexahyrdate (FeCl 2 .6H 2 O) and magnesium chloride hexahydrate (MgCl 2 .6H 2 O). 
     
     
         14 . The method of  claim 9 , wherein a molar ratio of a halide of said halide activator to said alloying agent is at most about 10:1. 
     
     
         15 . A method for coating a substrate with at least one layer comprising at least one elemental metal adjacent to said substrate, comprising:
 (a) coating at least a portion of said substrate with a slurry to generate a slurry-coated substrate, wherein said slurry comprises (i) a solvent, (ii) an alloying agent, wherein said alloying agent comprises said at least one elemental metal, and wherein said alloying agent is configured to diffuse into said substrate, (iii) a metal halide activator that facilitates diffusion of said at least one elemental metal to said substrate, and (iv) an inert species that aids in suspending said alloying agent in said solvent, wherein said inert species has a particle size that is less than or equal to about 200 mesh; and   (b) subjecting said slurry-coated substrate to annealing under conditions that are sufficient to diffuse said at least one elemental metal into said substrate, to generate a layer adjacent to said substrate comprising said at least one elemental metal.   
     
     
         16 . The method of  claim 15 , further comprising, prior to (b), incubating said slurry-coated substrate at an incubation temperature greater than a boiling temperature of said solvent, wherein said solvent is substantially removed from said slurry by evaporation to generate a dry film on said slurry-coated substrate. 
     
     
         17 . The method of  claim 16 , wherein said dry film (1) has a green strength suitable to survive flexing to a 20 inch diameter arc 20 times (positive and negative) and pass a tape test with small amount of powdering, and/or (2) is capable of surviving a high speed roll coating process. 
     
     
         18 . The method of  claim 15 , wherein, in (a), said coating is via one or more selected from the group consisting of roll coating, dipping, painting, spin coating, printing, spraying, slot coating, curtain coating, slide coating, and extrusion coating. 
     
     
         19 . The method of  claim 15 , wherein said substrate is a metal-containing substrate. 
     
     
         20 . The method of  claim 19 , wherein said metal-containing substrate comprises one or more of iron, copper and aluminum. 
     
     
         21 . The method of  claim 19 , wherein said metal-containing substrate is steel. 
     
     
         22 . The method of  claim 15 , wherein said layer comprises stainless steel. 
     
     
         23 . The method of  claim 15 , wherein said metal halide activator is hydrated. 
     
     
         24 . The method of  claim 23 , wherein said metal halide activator is selected from the group consisting of iron chloride tetrahydrate (FeCl 2 .4H 2 O), iron chloride hexahyrdate (FeCl 2 .6H 2 O) and magnesium chloride hexahydrate (MgCl 2 6H 2 O). 
     
     
         25 . The method of  claim 15 , a molar ratio of a halide of said metal halide activator to said at least one elemental metal is at most about 10:1. 
     
     
         26 . A method for forming a metal-containing object comprising a metal layer adjacent to a substrate, comprising:
 (a) coating at least a portion of said substrate with a slurry comprising an alloying agent having at least one elemental metal, thereby forming a slurry-coated substrate; and   (b) subjecting said slurry-coated substrate to annealing under conditions that are sufficient to form said metal layer adjacent to said substrate, wherein said metal layer is coupled to said substrate with the aid of a diffusion layer between said metal layer and said substrate, wherein an amount of said alloying agent in said diffusion layer changes with depth at a rate between about −0.01% per micrometer and −5.0% per micrometer as measured by x-ray photoelectron spectroscopy.   
     
     
         27 . The method of  claim 26 , wherein said slurry comprises a solvent, a halide activator and an inert species that aids in suspending said alloying agent in said slurry. 
     
     
         28 . The method of  claim 27 , wherein said inert species has a particle size that is less than or equal to about 200 mesh. 
     
     
         29 . The method of  claim 26 , wherein a molar ratio of a halide of said halide activator to said at least one elemental metal is at most about 10:1. 
     
     
         30 . The method of  claim 26 , wherein said substrate is a steel substrate.