Method of applying a wear resistant coating

Abstract

A method of applying a wear-resistant coating comprises mixing about 75% to about 85% by weight chromium carbide and about 15% to about 25% by weight nickel chromium to form a chromium carbide-nickel chromium mixture, and simultaneously heating the chromium carbide-nickel chromium mixture to about 1371 degrees Celsius to about 2204 degrees Celsius and applying the chromium carbide-nickel chromium mixture at a velocity in a range of about 305 meters feet per second to about 915 meters per second by high velocity oxygen fuel (HVOF) spraying.

1 . A method of applying a wear-resistant coating comprising:
 mixing about 75% to about 85% by weight chromium carbide and about 15% to about 25% by weight nickel chromium to form a chromium carbide-nickel chromium mixture; and   simultaneously heating the chromium carbide-nickel chromium mixture to a temperature in a range from about 1371 degrees Celsius to about 2204 degrees Celsius and applying the chromium carbide-nickel chromium mixture at a velocity in a range from about 305 meters feet per second to about 915 meters per second by high velocity oxygen fuel (HVOF) spraying.   
     
     
         2 . The method of  claim 1 , wherein spraying the chromium carbide-nickel chromium mixture comprises spraying the chromium carbide-nickel chromium mixture to a thickness in a range from about 203 microns to about 762 microns as sprayed. 
     
     
         3 . The method of  claim 1 , wherein spraying the chromium carbide-nickel chromium mixture comprises using a fuel gas selected from the group consisting of: hydrogen, kerosene, and propylene. 
     
     
         4 . The method of  claim 3 , wherein spraying the chromium carbide-nickel chromium mixture comprises spraying a hydrogen fuel gas at a flow rate in a range from about 661 liters per minute to about 755 liters per minute and spraying oxygen fuel gas at a flow rate in a range from about 189 liters per minute to about 283 liters per minute. 
     
     
         5 . The method of  claim 1 , wherein mixing about 75% to about 85% by weight chromium carbide and about 15% to about 25% by weight nickel chromium comprises mixing about 80% by weight chromium carbide and about 20% by weight nickel chromium. 
     
     
         6 . The method of  claim 1 , wherein mixing about 75% to about 85% by weight chromium carbide and about 15% to about 25% by weight nickel chromium comprises mixing chromium carbide having a particle size in a range from about 16 microns to about 45 microns and nickel chromium having a particle size in a range from about 16 microns to about 45 microns. 
     
     
         7 . The method of  claim 6 , wherein the chromium carbide-nickel chromium mixture is applied in the form of a blended powder or an alloyed powder. 
     
     
         8 . The method of  claim 1 , wherein a chromium carbide-nickel chromium mixture is fed into an HVOF spray gun at a rate in a range from about 45 grams per minute to about 90 grams per minute. 
     
     
         9 . The method of  claim 1 , wherein the wear-resistant coating has a substantially and predominantly lamellar splat structure with a plurality of isolated regions of cuboidal carbide phases. 
     
     
         10 . The method of  claim 9 , wherein the cuboidal carbide phases consist essentially of a discrete mixture of cuboidal Cr3C2 carbides, substantially lamellar precipitated matrix carbides of the form CrxCy where x=7 to 23 and y=3 to 6, fine lamellar nickel oxides, and a fine lamellar Ni—Cr binder. 
     
     
         11 . The method of  claim 1 , wherein the wear-resistant coating has:
 a microhardness in a range from about 850 Vickers Hardness to about 1150 Vickers Hardness;   a porosity of up to about 3%; and   a nominal oxide level in a range from about 10% to about 20%.   
     
     
         12 . The method of  claim 1 , wherein the wear-resistant coating is applied to a seal plate of a carbon seal. 
     
     
         13 . A method of applying a wear-resistant coating, the method comprising:
 mixing about 75% to about 85% by weight chromium carbide and about 15% to about 25% by weight nickel chromium to form a chromium carbide-nickel chromium mixture;   using an HVOF spray gun to spray a fuel gas at a flow rate in a range from about 661 liters per minute to about 755 liters per minute, and an oxygen gas at a flow rate in a range from about 189 liters per minute to about 283 liters per minute to generate a HVOF jet;   feeding the chromium carbide-nickel chromium mixture into the HVOF jet at a rate in a range from about 45 grams per minute to about 90 grams per minute, and at a velocity in a range from about 315 meters per second to about 915 meters per second;   heating the chromium carbide-nickel chromium mixture in the HVOF jet to a temperature in a range from about 1371 degrees Celsius to about 2204 degrees Celsius; and   depositing the chromium carbide-nickel chromium mixture on a surface to form a wear-resistant coating.   
     
     
         14 . The method of  claim 13 , and further comprising:
 spraying in the HVOF jet a nitrogen carrier gas with the HVOF spray gun at a flow rate in a range from about 11.8 liters per minute to about 16.5 liters per minute.   
     
     
         15 . The method of  claim 13 , and further comprising:
 spraying in the HVOF jet a cooling gas with the HVOF spray gun at a flow rate in a range from about 283 liters per minute to about 425 liters per minute.   
     
     
         16 . The method of  claim 13 , wherein the surface is rotated at speeds in a range from about 61 meters per minute to about 122 meters per minute. 
     
     
         17 . The method of  claim 13 , wherein the HVOF spray gun is:
 positioned a distance from the surface in a range from about 23 centimeters to about 30.5 centimeters;   positioned at an angle in a range from about 45 degrees to about 90 degrees relative to a horizontal plane across the surface; and   traversed at a speed in a range from about 20.3 centimeters per minute to about 101.6 centimeters per minute.   
     
     
         18 . The method of  claim 13 , wherein the wear-resistant coating is deposited on the surface to form a substantially and predominantly lamellar splat structure with a plurality of isolated regions of cuboidal carbide phase, wherein the cuboidal carbide phases consist essentially of a discrete mixture of cuboidal Cr3C2 carbides, substantially lamellar precipitated matrix carbides of the form CrxCy where x=7 to 23 and y=3 to 6, fine lamellar nickel oxides, and a fine lamellar Ni—Cr binder. 
     
     
         19 . The method of  claim 13 , wherein the wear-resistant coating is applied to a thickness in a range from about 203 microns to about 762 microns. 
     
     
         20 . A method of applying a wear-resistant coating comprising:
 mixing about 75% to about 85% by weight chromium carbide and about 15% to about 25% by weight nickel chromium to form a chromium carbide-nickel chromium mixture; and   heating the chromium carbide-nickel chromium mixture to a temperature in a range from about 1371 degrees Celsius to about 2204 degrees Celsius;   applying the chromium carbide-nickel chromium mixture at a velocity in a range from about 305 meters feet per second to about 915 meters per second by high velocity oxygen fuel (HVOF) spraying; and   impacting the chromium carbide-nickel chromium mixture on a surface to form a substantially and predominantly lamellar splat structure with a plurality of isolated regions of cuboidal carbide phase.