Method of applying a coating to a perforated substrate

Abstract

The present invention provides a method of applying a coating to a perforated substrate, the method comprising: (a) providing a perforated substrate having a substrate first surface, a substrate second surface and one or more perforations traversing the substrate from the first surface to the second surface; (b) bringing the substrate first surface into contact with a perforation blocking solid; (c) applying a metallic thermal spray coating composition to the substrate second surface using a thermal spray technique; and (d) separating the perforation blocking solid from the substrate first surface to provide a substrate having a metallic thermal spray coating disposed upon the substrate second surface and wherein the perforations are not occluded by the metallic thermal spray coating. Among its many other uses, the method is also useful for applying thermal spray coatings to the interior surface of valve cages used in flow control valves.

What is claimed is: 
     
         1 . A method of applying a coating to a perforated substrate, the method comprising:
 (a) providing a perforated substrate having a substrate first surface, a substrate second surface and one or more perforations traversing the substrate from the first surface to the second surface;   (b) bringing the substrate first surface into contact with a perforation blocking solid;   (c) applying a metallic thermal spray coating composition to the substrate second surface using a thermal spray technique; and   (d) separating the perforation blocking solid from the substrate first surface to provide a substrate having a metallic thermal spray coating disposed upon the substrate second surface and wherein the perforations are not occluded by the metallic thermal spray coating.   
     
     
         2 . The method according to  claim 1 , wherein the perforated substrate is a metallic substrate. 
     
     
         3 . The method according to  claim 1 , wherein the substrate first surface and the substrate second surface are substantially parallel surfaces. 
     
     
         4 . The method according to  claim 1 , wherein the substrate first surface and the substrate second surface are substantially non-parallel surfaces. 
     
     
         5 . The method according to  claim 1 , wherein the perforations are substantially orthogonal to the substrate first surface and the substrate second surface. 
     
     
         6 . The method according to  claim 1 , wherein the perforations are substantially non-orthogonal to the substrate first surface and the substrate second surface. 
     
     
         7 . The method according to  claim 1 , wherein the perforation blocking solid is made of sheet metal. 
     
     
         8 . The method according to  claim 7 , wherein the perforation blocking solid is characterized by a surface roughness of less than 32 Ra. 
     
     
         9 . The method according to  claim 1 , wherein the thermal spray technique is an HVAF thermal spray technique. 
     
     
         10 . The method according to  claim 1 , wherein the thermal spray technique is an HVOF thermal spray technique. 
     
     
         11 . The method according to  claim 1 , wherein metallic thermal spray coating composition comprises tungsten carbide, cobalt and chromium and is characterized by an average particle size in a range from about 1 micron to about 100 microns. 
     
     
         12 . A method of applying a coating to a perforated article, the method comprising:
 (a) providing a perforated article having a first surface, a second surface and one or more perforations traversing the article from the first surface to the second surface;   (b) bringing the first surface into contact with a perforation blocking solid;   (c) applying a metallic thermal spray coating composition to the second surface using a thermal spray technique; and   (d) separating the perforation blocking solid from the first surface to provide an article having a metallic thermal spray coating disposed upon the second surface and wherein the perforations are not occluded by the metallic thermal spray coating.   
     
     
         13 . A method of applying a coating to a perforated cylindrical metal article, the method comprising:
 (a) providing a perforated cylindrical metal article having an outer first surface and an inner second surface and one or more perforations traversing the substrate from the first surface to the second surface;   (b) wrapping the outer first surface of the perforated cylindrical metal article with a perforation blocking solid;   (c) applying a metallic thermal spray coating composition to the inner second surface using a thermal spray technique; and   (d) separating the perforation blocking solid from the substrate first surface to provide a cylindrical metal article having a metallic thermal spray coating disposed upon the substrate second surface and wherein the perforations are not occluded by the metallic thermal spray coating.   
     
     
         14 . The method according to  claim 13 , wherein the article is a cage for a flow control valve. 
     
     
         15 . The method according to  claim 13 , wherein the perforations are essentially round and are characterized by a perforation average diameter in a range from about 0.1 mm to about 10 mm. 
     
     
         16 . The method according to  claim 13 , wherein the perforation blocking solid is made of sheet metal. 
     
     
         17 . The method according to  claim 16 , wherein the perforation blocking solid is characterized by a surface roughness of less than 32 Ra. 
     
     
         18 . The method according to  claim 13 , wherein the thermal spray technique is an HVAF thermal spray technique. 
     
     
         19 . The method according to  claim 13 , wherein the thermal spray technique is an HVOF thermal spray technique. 
     
     
         20 . The method according to  claim 13 , wherein metallic thermal spray coating composition comprises tungsten carbide, cobalt and chromium and is characterized by an average particle size in a range from about 1 micron to about 100 microns. 
     
     
         21 . The method according to  claim 13 , wherein metallic thermal spray coating composition comprises chromium carbide, nickel and chromium and is characterized by an average particle size in a range from about 1 micron to about 100 microns.