Method for processing alloys via high-current density ion implantation

Abstract

A surface processing method and power transmission component includes transforming by high current density ion implantation (high intensity plasma ion processing) a surface region of a metal alloy into a hardened surface region at a temperature that is less than a heat treating temperature of the metal alloy. The metal alloy includes between 1.5 wt % and 15 wt % Ni, between 5 wt % and 30 wt % Co, up to 1.0 wt % carbon, and up to 15 wt % of a carbide-forming element, such as molybdenum, chromium, tungsten, vanadium or combinations thereof, that can react with carbon to form metal carbide precipitates of the form M 2 C. The surface processing temperature, vacuum pressure, precursor gas flow and ratio, and time of processing are controlled to provide a desirable hardened surface region having a gradual transition in nitrogen concentration. A vapor deposition process deposits an amorphous hydrogenated carbon coating on the hardened surface region of the metal alloy. An intermediate coating between the coating and the hardened surface region promotes adhesion between the coating and hardened surface region.

1 . A surface processing method comprising the steps of: 
 transforming a surface region of a metal alloy into a hardened surface region at a temperature that is less than a heat treating temperature of the metal alloy.    
   
   
       2 - 26 . (canceled)  
   
   
       27 . The method as recited in  claim 1 , further comprising the steps of: 
 applying a heat treatment to said metal alloy; and    combining said step of applying a heat treatment with said step of transforming said surface region when at least one condition of said heat treatment corresponds to at least one condition of said hardened surface.    
   
   
       28 . The method as recited in  claim 27 , wherein said at least one condition of said heat treatment is a temperature condition.  
   
   
       29 . The method as recited in  claim 1 , further comprising the step of forming a coating on said hardened surface region.  
   
   
       30 . The method as recited in  claim 29 , further comprising the step of forming an intermediate coating between said coating and said hardened surface region.  
   
   
       31 . The method as recited in  claim 1 , wherein said transforming step includes processes selected from the group consisting of carburizing, nitriding, carbo-nitriding, nitro-carburizing, boronizing, and boriding.  
   
   
       32 . The method as recited in  claim 1 , further comprising the step of transforming the surface region by high current density ion implantation.  
   
   
       33 . The method as recited in  claim 1 , further comprising the step of nitriding said metal alloy, said nitriding step including transforming the surface region into a nitrogen-containing solid solution surface region.  
   
   
       34 . The method as recited in  claim 1 , further comprising the step of using a gas atmosphere comprising between about 10% and 100% nitrogen to transform the surface region.  
   
   
       35 . The method as recited in  claim 1 , further comprising the step of using a gas atmosphere pressure between 0.5 mtorr and 5.0 mtorr to transform the surface region.  
   
   
       36 . The method as recited in  claim 1 , further comprising the step of inducing a bias voltage on the metal alloy between 200V and 1500V to transform the surface region.  
   
   
       37 . The method as recited in  claim 1 , further comprising the step of using a plasma discharge voltage of between 30V and 150V to transform the surface region by ionizing precursor processing gases.  
   
   
       38 . The method as recited in  claim 1 , wherein said nitriding step further comprises the step of removing oxides on the surface region during the transforming of said surface region into said hardened surface region.  
   
   
       39 . The method as recited in  claim 1 , wherein said nitriding step further comprises transforming the surface region of a metal alloy into the hardened surface region at a temperature between about 700° F. and 1000° F.  
   
   
       40 . The method as recited in  claim 1 , wherein said nitriding step further comprises the step of forming a coating on the hardened surface region.  
   
   
       41 . A surface processing method comprising the steps of: 
 solutionizing a metal alloy;    quenching said metal alloy;    reheating said quenched metal alloy to age said quenched metal alloy;    transforming a surface region of said metal alloy into a surface hardened region; and    combining said step of reheating with said step of transforming said surface region when at least one condition of said reheating step corresponds to at least one condition of said hardened surface.    
   
   
       42 . The method as recited in  claim 41 , wherein said transforming step is performed at a temperature that is less than a temperature of said reheating step.  
   
   
       43 . The method as recited in  claim 41 , further comprising the step of forming a coating on said hardened surface.  
   
   
       44 . The method as recited in  claim 43 , further comprising the step of forming an intermediate coating between said coating and said hardened surface.  
   
   
       45 . The method as recited in  claim 41 , further comprising the step of nitriding said metal alloy.  
   
   
       46 . The method as recited in  claim 41 , further comprising the steps of: 
 refrigerating said quenched metal alloy; and    reheating said quenched metal alloy to temper said quenched metal alloy.    
   
   
       47 . The method as recited in  claim 41 , wherein said solutionizing step includes the step of austenitizing said metal alloy.  
   
   
       48 . A surface processing method comprising the steps of: 
 providing a metal alloy with an associated composition and associated heat treating conditions; and    transforming a surface region of said metal alloy to a hardened surface region at a temperature that is less than said heat treating conditions of said metal alloy.    
   
   
       49 . The method as recited in  claim 48 , further comprising the step of forming a coating on said hardened surface.  
   
   
       50 . The method as recited in  claim 48 , wherein said metal alloy comprises at least 5 wt % cobalt.  
   
   
       51 . The method as recited in  claim 48 , wherein said metal alloy comprises at least 1.5 wt % nickel.  
   
   
       52 . The method as recited in  claim 48 , wherein said metal alloy comprises up to 1.0 wt % carbon.  
   
   
       53 . The method as recited in  claim 48 , wherein said metal alloy comprises less than 20 wt % of molybdenum, chromium, tungsten, or vanadium and combinations thereof.  
   
   
       54 . The method as recited in  claim 48 , wherein said forming said coating step further comprises forming an amorphous hydrogenated carbon coating on said hardened surface region.  
   
   
       55 . The method as recited in  claim 49 , wherein said forming said coating step further comprises forming a intermediate coating between said coating and said hardened surface.  
   
   
       56 . The method as recited in  claim 49 , wherein said forming said coating step further comprises forming a metallic intermediate coating between said coating and said hardened surface.  
   
   
       57 . The method as recited in  claim 48 , wherein said metal alloy is used in a power transmission system, a gear, a shaft, a spring, a bearing, or as armor plating.