Laser assisted interstitial alloying for improved wear resistance

Abstract

A method of enhancing wear resistance of a metallic substrate includes applying a coating of an interstitial element to a surface of a substrate. A laser beam is directed onto a localized area of the metallic substrate coated with the interstitial element locally raising a temperature of the metallic substrate to a temperature causing the interstitial element to diffuse into the substrate. A layer of alloy including the interstitial element is generated onto the localized area of the metallic substrate. A focal point of the laser beam is disposed at a location spaced from the surface of the substrate for optimizing a power density of the laser beam at the surface of the substrate. The coating of interstitial element not diffused into the substrate is removed exposing the layer of alloy including the interstitial element.

What is claimed is: 
     
         1 . A method of enhancing wear resistance of a metallic substrate, comprising the steps of:
 providing a metallic substrate;   applying a coating including an interstitial element to a surface of the substrate;   directing a laser beam onto a localized area of the metallic substrate coated with the interstitial element thereby locally raising a temperature of the metallic substrate to a temperature causing the interstitial element to diffuse into the substrate providing a layer of alloy including the interstitial element onto the localized area of the metallic substrate;   positioning a focal point of the laser beam at a location spaced from the surface of the substrate for optimizing a power density of the laser beam at the surface of the substrate; and   removing the coating of interstitial element not diffused into the substrate thereby exposing the layer of alloy including the interstitial element.   
     
     
         2 . The method set forth in  claim 1 , wherein said step of directing the laser beam is further defined by directing the laser beam along a three dimensional surface of the metallic substrate. 
     
     
         3 . The method set forth in  claim 2 , wherein said step of directing the laser beam along a three dimensional surface of the metallic substrate is further defined by directing said laser beam with computer data defining a configuration of said metallic substrate. 
     
     
         4 . The method set forth in  claim 1 , wherein said step of applying a coating of an interstitial element is further defined by providing a coating comprising at least one of hydrogen, boron, carbon, nitrogen, or combinations thereof. 
     
     
         5 . The method set forth in  claim 1 , wherein said step of providing a metallic substrate is further defined by providing iron-alloys (steel), nickel-alloys, cobalt-alloys, aluminum-alloys, and copper-alloys. 
     
     
         6 . The method set forth in  claim 1 , wherein said step of providing a metallic substrate is further defined by providing a metallic substrate with a surface roughness having an Ra value less than about 50 microns and an Rt less than about 100 microns. 
     
     
         7 . The method set forth in  claim 1 , wherein said step of causing the interstitial element to diffuse into the substrate providing a layer of alloy including the interstitial element is further defined by causing the interstitial element to diffuse into the substrate to a depth of between 30 microns and 500 microns. 
     
     
         8 . The method set forth in  claim 7 , further including controlling the depth of diffusion of the interstitial element by adjusting power density and laser traverse speed of the laser beam. 
     
     
         9 . The method set forth in  claim 1 , wherein said step of applying a coating of an interstitial element to the substrate is further defined by applying a powdered interstitial element using an aerosol spray or applying a tape of comprising the interstitial element to a predetermined location. 
     
     
         10 . The method set forth in  claim 1 , wherein directing a laser beam onto a localized area of the metallic substrate is further defined by adjusting a shape of the laser beam projected onto the localize area of the metallic substrate. 
     
     
         11 . The method set forth in  claim 1 , wherein said step of directing a laser beam onto a localized area of the metallic substrate is further defined by providing a laser beam comprising a CO 2  laser, a diode laser, a fiber optic laser delivering a laser beam directly to the surface of the substrate, and equivalents thereof. 
     
     
         12 . The method set forth in  claim 1 , further including the step of heating the metallic substrate during or prior to applying the coating of interstitial element for vaporizing solvent disposed in the coating of the interstitial element. 
     
     
         13 . The method set forth in  claim 1 , wherein said step of applying a coating of interstitial element is further defined by applying a coating including the interstitial element comprising a volatile solvent capable of evaporating from the coating including the interstitial element while the substrate is disposed at ambient temperature. 
     
     
         14 . The method set forth in  claim 1 , wherein said step of directing a laser beam onto a localized area of the metallic substrate is further defined by directing a divergent laser beam onto the metallic substrate.