A method of coating a sheet of steel

Abstract

A method of coating a sheet of steel is disclosed. The method includes preparing a surface of the sheet of steel by grit blasting with brown fused alumina. A first metal deposition coating, including aluminium, is applied and then a second metal deposition coating, including aluminium and a least one first doping material, is applied to the first coating. Finally a barrier coating including potassium silicate is applied to the second metal deposition coating.

1 . A method of coating a sheet of steel comprising the steps:
 preparing a surface of a sheet of steel that is to be coated;   applying a first metal deposition coating to said sheet of steel, said first coating comprising aluminium;   applying a second metal deposition coating to said first coating, said second coating comprising aluminium and a least one first doping material; and applying a barrier coating to said second metal deposition coating.   
     
     
         2 . The method according to  claim 1 , wherein said surface of said sheet of steel is prepared by grit blasting. 
     
     
         3 . The method according to  claim 2 , wherein said grit blasting uses a grit comprising brown fused alumina. 
     
     
         4 . The method according to  claim 1 , wherein said first coating further comprises at least one second doping material. 
     
     
         5 . The method according to  claim 4 , wherein said second doping material comprises at least one of zinc, molybdenum, Gallium, tin and indium. 
     
     
         6 . The method according to  claim 1 , wherein said first metal deposition coating is applied to a thickness of between 75 and 200 μm. 
     
     
         7 . The method according to  claim 1 , wherein said first doping material comprises at least one of titanium, chromium, manganese, boron, aluminium oxide, titanium oxide, chromium oxide, manganese oxide, boron oxide, boron nitride, boron carbide and tungsten carbide. 
     
     
         8 . The method according to  claim 1 , wherein said second metal deposition coating is applied in a plurality of stages including a first stage and a second stage and wherein a particle accelerator used in the coating applications operates so as to accelerate the particles more in the first stage than the second stage. 
     
     
         9 . The method according to  claim 1 , wherein said second metal deposition coating is applied in a plurality of stages including a first stage and a second stage and wherein a particle accelerator used in the coating applications operates so that a surface produced in said first stage has a surface roughness less than a surface roughness produced in said second stage. 
     
     
         10 . The method according to  claim 1 , wherein said second metal deposition coating is applied to a thickness of between 150 and 300 μm. 
     
     
         11 . The method according to  claim 1 , wherein said barrier coating comprises an inorganic heat resistant coating material. 
     
     
         12 . The method according to  claim 1 , wherein said barrier coating comprises a potassium silicate coating material. 
     
     
         13 . The method according to  claim 1 , wherein said barrier coating is applied to a thickness of between 5 and 25 μm. 
     
     
         14 . The method according to  claim 1 , wherein at least one of said first and second metal deposition coatings are applied using at least one of the metal deposition techniques of arc spray, wire spray, twin wire arc spray, air plasma and cold spray. 
     
     
         15 . A coating for a sheet of steel, the coating comprising:
 a first metal deposition coating comprising aluminium and applied to a prepared surface of a sheet of steel;   a second metal deposition coating comprising aluminium and at least one first doping material and applied to said first metal deposition coating; and   a barrier coating applied to said second metal deposition coating.   
     
     
         16 .- 24 . (canceled) 
     
     
         25 . A sheet material comprising:
 a sheet of steel material; and   a coating according to  claim 15  applied to said sheet of steel material.   
     
     
         26 .- 27 . (canceled) 
     
     
         28 . An article comprising at least one sheet material according to  claim 25 . 
     
     
         29 .- 30 . (canceled) 
     
     
         31 . An apparatus for applying a coating to a sheet of steel, the apparatus comprising:
 a frame for supporting a plurality of metal deposition coating applicators;   an applicator moving device for moving said applicators relative to said frame;   at least one applicator for applying at least one first metal deposition coating and at least one second metal deposition coating to a sheet of steel; and   at least one processor for controlling said applicators and said applicator moving device.   
     
     
         32 . The apparatus according to  claim 31 , wherein at least one of said applicator uses at least one of the metal deposition techniques of arc spray, wire spray, twin wire arc spray, hot plasma and cold spray. 
     
     
         33 . The apparatus according to  claim 31  comprising a plurality of applicators for applying at least one first metal deposition coating and at least one second metal deposition coating to a sheet of steel. 
     
     
         34 .- 38 . (canceled)