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 - 132 . (canceled) 
     
     
         133 . A method for forming, adjacent to a substrate, a layer of stainless steel comprising a transition metal, the method comprising:
 (a) coating at least a portion of said substrate with a slurry to generate a slurry-coated substrate, which slurry comprises:
 (i) a solvent; 
 (ii) an alloying agent comprising said transition metal; 
 (iii) a metal halide activator configured to facilitate diffusion of an amount of said transition metal in said slurry into said substrate, wherein a molar ratio of a halide of said halide activator to said transition metal is at most about 10:1; and 
 (iv) an inert species that aids in dispersing said alloying agent in said solvent; 
 wherein said slurry does not comprise an organic binder; and 
   (b) subjecting said slurry-coated substrate to annealing under conditions that are sufficient to diffuse said amount of said transition metal in said slurry into said substrate, to generate said layer of stainless steel comprising said transition metal adjacent to said substrate.   
     
     
         134 . The method of  claim 133 , wherein said annealing conditions in (b) comprise an annealing atmosphere comprising hydrogen (H 2 ). 
     
     
         135 . The method of  claim 133 , wherein said annealing conditions in (b) comprise an annealing temperature is from about 800° C. to 1300° C. 
     
     
         136 . The method of  claim 133 , wherein, during (b), at least about 95% of said transition metal in said slurry diffuses into said substrate. 
     
     
         137 . The method of  claim 133 , wherein, prior to (b), said slurry-coated substrate comprises a dry film of said slurry, which dry film is capable of surviving a roll coating process. 
     
     
         138 . The method of  claim 137 , wherein said dry film has a green strength suitable to survive flexing to a 20 inch diameter arc 20 times (positive and negative). 
     
     
         139 . The method of  claim 138 , wherein said dry film is capable of passing a tape test with small amount of powdering. 
     
     
         140 . The method of  claim 133 , wherein, prior to (a), said substrate is provided in a coil; and wherein said coil is unwound prior to said coating in (a). 
     
     
         141 . The method of  claim 140 , wherein, after (a), said unwound coil is wound into a coated coil. 
     
     
         142 . The method of  claim 133 , wherein, prior to (a), said substrate is provided as a wire, pipe, tube, slab, a coiled mesh, a dipped formed part, a sheet, a wire rope, or a rod. 
     
     
         143 . The method of  claim 133 , 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. 
     
     
         144 . The method of  claim 133 , further comprising, in (a), coating said at least said portion of said substrate with said slurry in multiple cycles. 
     
     
         145 . The method of  claim 133 , wherein said layer of stainless steel comprises an outer layer and a bonding layer adjacent to said outer layer. 
     
     
         146 . The method of  claim 145 , wherein said transition metal has a concentration that varies by less than about 20 wt. % in said outer layer. 
     
     
         147 . The method of  claim 145 , wherein said transition metal has a concentration that decreases to less than about 1.0 wt. % in said bonding layer. 
     
     
         148 . The method of  claim 145 , wherein said layer of stainless steel further comprises a core region adjacent to said bonding layer; which core region comprises substantially the same composition as said substrate. 
     
     
         149 . The method of  claim 133 , wherein said alloying agent is selected from the group consisting of iron, chromium, nickel, vanadium, titanium, tungsten, molybdenum, cobalt, manganese, zirconium, niobium and combinations thereof. 
     
     
         150 . The method of  claim 133 , wherein said transition metal is selected from the group consisting of chromium, nickel, aluminum, silicon, vanadium, titanium, boron, tungsten, molybdenum, cobalt, manganese, zirconium, niobium and combinations thereof. 
     
     
         151 . The method of  claim 133 , wherein said metal halide activator is selected from the group 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 (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. 
     
     
         152 . A composition for forming a layer of stainless steel comprising a transition metal, the composition comprising:
 a slurry comprising:
 (i) a solvent; 
 (ii) an alloying agent comprising said transition metal; 
 (iii) a metal halide activator configured to facilitate diffusion of an amount of said transition metal in said slurry into said substrate, wherein a molar ratio of a halide of said halide activator to said transition metal is at most about 10:1; and 
 (iv) an inert species that aids in dispersing said alloying agent in said solvent, 
   wherein said slurry does not comprise an organic binder; and   wherein said slurry is configured to form said layer of stainless steel comprising said transition metal upon diffusion of said amount of said transition metal in said slurry into a substrate.