Crack resistant thermal spray alloy

Abstract

The present disclosure provides a thermal spray alloy system that is more resistant to wear and/or corrosion than conventional alloy compositions. The disclosed alloys minimize or eliminate micro-cracks within the formed coating on the tool. The alloy comprises carbon, boron, and a fluxing agent selected from the group of aluminum, magnesium, or lithium. The alloy may also comprise titanium, silicon, manganese, molybdenum, nickel, and chromium, as well as other elements. The object to be coated may be any downhole component used in the oil and gas industry, or may be applied to any object or tool that needs an increased wear and/or corrosive protection layer including in diverse fields such as marine, chemical processing, and refining. A thermal spray coating with the disclosed alloy composition provides increased strength and resistance to spalling, breaking, cracking, deforming, and crack formation, as well as metallurgical bonding between the coating and the substrate.

What is claimed is: 
     
         1 . A composition for thermally spraying to a substrate, the composition comprising iron alloyed with the following components:
 at least 0.3 wt % carbon;   at least 5.0 wt % boron; and   at least 0.5 wt % of a fluxing agent selected from the group consisting of aluminum, magnesium, or lithium.   
     
     
         2 . The composition of  claim 1 , wherein the composition comprises at least 0.5 wt % lithium. 
     
     
         3 . The composition of  claim 1 , wherein the composition comprises at least 5.0 wt % lithium. 
     
     
         4 . The composition of  claim 1 , wherein the composition comprises at least 0.5 wt % magnesium. 
     
     
         5 . The composition of  claim 1 , wherein the composition comprises at least 5.0 wt % magnesium. 
     
     
         6 . The composition of  claim 1 , wherein the composition comprises at least 0.5 wt % aluminum. 
     
     
         7 . The composition of  claim 1 , wherein the composition comprises at least 2.0 wt % aluminum and at least 0.5 wt % lithium. 
     
     
         8 . The composition of  claim 1 , wherein the composition further comprises:
 at least 0.5 wt % carbon; and   at least 7.0 wt % boron.   
     
     
         9 . The composition of  claim 1 , wherein the composition further comprises:
 at least 2.0 wt % aluminum;   at least 1.0 wt % nickel; and   at least 1.0 wt % titanium.   
     
     
         10 . The composition of  claim 1 , further comprising a plurality of reactants that create an exothermic reaction when ignited and thermally sprayed onto the substrate. 
     
     
         11 . The composition of  claim 1 , wherein the amount of the fluxing agent is effective to prevent oxide film formation on droplets of the composition during thermal spray. 
     
     
         12 . The composition of  claim 1 , wherein the amount of the fluxing agent is effective to increase droplet temperature of the composition during thermal spray. 
     
     
         13 . The composition of  claim 1 , wherein the amount of the fluxing agent is effective to cause metallurgical bonding between a layer of sprayed metallic material and the substrate. 
     
     
         14 . The composition of  claim 1 , wherein the composition is effective to prevent micro-cracks from forming in the thermal spray. 
     
     
         15 . The composition of  claim 1 , wherein the composition is effective to reduce the amount of micro-cracks within a layer of sprayed metallic material on the substrate. 
     
     
         16 . The composition of  claim 1 , wherein the composition is effective to diffuse at least a portion of the carbon and boron to a base material of the substrate. 
     
     
         17 . A modified downhole component, comprising:
 a downhole component with an external surface; and   a layer of metallic material that is thermally sprayed onto a portion of the external surface, wherein the layer of metallic material comprises a composition, at least prior to being sprayed, of at least 0.3 wt % carbon, at least 5.0 wt % boron, and at least 0.5 wt % of a fluxing agent selected from the group consisting of aluminum, magnesium, or lithium.   
     
     
         18 . The component of  claim 17 , wherein the composition comprises at least 2.0 wt % aluminum. 
     
     
         19 . The component of  claim 17 , wherein the composition comprises at least 0.5 wt % lithium. 
     
     
         20 . The component of  claim 17 , wherein the component is a drill pipe. 
     
     
         21 . The component of  claim 17 , wherein the component is a drill pipe tool joint. 
     
     
         22 . The component of  claim 17 , wherein the layer of metallic material has a thickness of between about 0.010 inches and 0.10 inches. 
     
     
         23 . The component of  claim 17 , wherein the layer of metallic material has a thickness of between about 0.10 inches and 1.0 inches. 
     
     
         24 . The component of  claim 17 , wherein the layer of metallic material has a thickness of between about 1.0 inches and 3.0 inches. 
     
     
         25 . The component of  claim 17 , wherein at least a portion of the carbon and boron has diffused from the layer of metallic material to a base material of the downhole component. 
     
     
         26 . The component of  claim 17 , wherein the layer of metallic material is resistant to micro-cracks. 
     
     
         27 . The component of  claim 17 , wherein the layer of metallic material comprises substantially no micro-cracks. 
     
     
         28 . The component of  claim 17 , wherein the layer of metallic material is at least partially metallurgically bonded to the downhole component. 
     
     
         29 . The component of  claim 17 , wherein the layer of metallic material is formed by an exothermic reaction. 
     
     
         30 . The component of  claim 17 , further comprising one or more reinforcing structures embedded within the layer of metallic material. 
     
     
         31 . The component of  claim 30 , wherein the one or more reinforcing structures comprises one or more continuous wires. 
     
     
         32 . The component of  claim 30 , wherein the one or more reinforcing structures comprises a plurality of whiskers. 
     
     
         33 . A modified downhole component, comprising:
 a downhole component with an external surface; and   a layer of metallic material that is thermal sprayed onto a portion of the external surface, wherein the layer of material is at least partially metallurgically bonded to the downhole component.   
     
     
         34 . The component of  claim 33 , wherein the composition of the layer of material further comprises iron alloyed with the following components:
 at least 0.3 wt % carbon;   at least 5.0 wt % boron; and   at least 0.5 wt % of a fluxing agent selected from the group consisting of aluminum, magnesium, or lithium.   
     
     
         35 . The component of  claim 34 , wherein the amount of the fluxing agent is effective to cause the metallurgical bonding. 
     
     
         36 . The component of  claim 33 , wherein the composition comprises a plurality of reactants that create an exothermic reaction when ignited and thermally sprayed onto the substrate, wherein the composition comprises at least 0.5 wt % of a lithium compound. 
     
     
         37 . A method for thermally applying a coating to a substrate, comprising:
 thermally spraying metallic material on an external surface of a substrate to form a thermal spray layer on the substrate, wherein the material, at least prior to being sprayed, comprises iron alloyed with the following components:   at least 0.3 wt % carbon;   at least 5.0 wt % boron; and   at least 0.5 wt % of a fluxing agent selected from the group consisting of aluminum, magnesium, or lithium.   
     
     
         38 . The method of  claim 37 , further comprising embedding one or more reinforcing structures into the thermal spray layer. 
     
     
         39 . The method of  claim 38 , further comprising spraying the one or more reinforcing structures onto the external surface of the substrate by compressed gas. 
     
     
         40 . The method of  claim 37 , further comprising metallurgically bonding the sprayed metallic material with the substrate. 
     
     
         41 . The method of  claim 37 , further comprising metallurgically bonding together droplets of the sprayed metallic material. 
     
     
         42 . The method of  claim 37 , further comprising diffusing boron and carbon between the thermal spray layer and the substrate. 
     
     
         43 . The method of  claim 37 , further comprising creating an exothermic reaction during the thermal spray step. 
     
     
         44 . The method of  claim 43 , further comprising igniting a plurality of reactants within a cored wire to create the exothermic reaction. 
     
     
         45 . The method of  claim 43 , further comprising increasing droplet temperature of the sprayed metallic material based on the fluxing agent. 
     
     
         46 . The method of  claim 37 , further comprising forming a layer of thermally sprayed material on the substrate that is between about 0.010 inches and 0.10 inches. 
     
     
         47 . The method of  claim 37 , further comprising forming a layer of thermally sprayed material on the substrate that is at least 0.1″ thick. 
     
     
         48 . The method of  claim 37 , further comprising forming a layer of thermally sprayed material on the substrate that is at least 1.0″ thick. 
     
     
         49 . The method of  claim 37 , further comprising preventing oxide film formation on droplets of the sprayed metallic material.