Method of manufacturing high-conductivity wear resistant surface on a soft substrate

Abstract

A method of forming a valve seat of an engine head formed from a first composition includes forming a groove at a predetermined valve seat location of a bore defined by the engine head. A source of directed heat energy preheats at least the valve seat location to about a temperature of the melting point of the first composition with the source of directed heat energy. The source of directed heat energy is infused with a material having a second composition generating a melt pool upon the groove by direct metal deposition with the melt pool including the second composition. The second composition includes a heat conductivity generally equal to a heat conductivity of the first composition for providing efficient transfer of heat energy from the first composition to the second composition.

What is claimed is: 
     
         1 . A method of forming a valve seat of an engine head formed from a first composition includes the steps of:
 forming a groove at a predetermined valve seat location of a bore defined by said engine head;   providing a source of directed heat energy;   preheating at least said valve seat location to about a temperature of the melting point of the first composition with the source of directed heat energy;   infusing the source of directed heat energy with a material having a second composition and generating a melt pool upon the groove by direct metal deposition, with the melt pool including the second composition; and   said second composition including a heat conductivity generally equal to or greater than a heat conductivity of the first composition for providing efficient transfer of heat energy from the first composition to the second composition.   
     
     
         2 . The method set forth in  claim 1 , wherein said step of infusing the source of directed heat energy with a material having a second composition is further defined by providing a second composition comprising:
 copper in the amount of 40-50 percent by weight;   cobalt in the amount of 15-25 percent by weight;   carbon in the amount of less than 0.1 percent by weight;   chromium in the amount of 7-10 percent by weight;   molybdenum in the amount of 8-12 percent by weight;   nickel in the amount of 10-15 percent by weight;   silicon in the amount of 2-5 percent by weight;   iron in the amount of less than 1.5 percent by weight;   hafnium in the amount of less than 1.5 percent by weight;   niobium in the amount of 0.5-2 percent by weight;   manganese in the amount of less than 2 percent by weight.   
     
     
         3 . The method set forth in  claim 1 , wherein said step of preheating at least said valve seat location to about a temperature of the melting point is further defined by melting a surface of the valve seat location. 
     
     
         4 . The method set forth in  claim 3 , wherein said step of preheating a surface of the valve seat location is further defined by raising a temperature of the valve seat to between about 250° C. and 450° C. 
     
     
         5 . The method set forth in  claim 1 , further including the step of melting a surface of the valve seat location by raising the temperature of the valve seat location to between about 550° C. and 660° C. 
     
     
         6 . The method set forth in  claim 1 , further including the step of preheating of the engine head for slowing the rate of cooling after direct metal deposition of the second composition onto the valve seat location. 
     
     
         7 . The method set forth in  claim 1 , wherein said step of direct metal deposition is further defined by rotating a direct metal deposition nozzle relative to a valve seat of an engine block. 
     
     
         8 . The method set forth in  claim 1 , wherein said step of direct metal deposition is further defined by rotating the valve seat of the engine block relative to a direct metal deposition nozzle. 
     
     
         9 . The method set forth in  claim 1 , wherein said step of providing a source of directed heat energy is further defined by providing a laser beam, a plasma torch, or a TIG welding torch. 
     
     
         10 . The method set forth in  claim 1 , further including the step of cooling the melt pool including the second composition thereby forming the valve seat and machining the cooled melt pool to a predetermined geometric shape. 
     
     
         11 . The method set forth in  claim 1 , wherein said step of forming a groove is further defined by forming a groove having a generally constant radius of between about three and ten millimeters having a chamfered wall with an angle ranging between about 30° and 70°. 
     
     
         12 . The method set forth in  claim 1 , further including the step of machining the second composition after the second composition has cooled. 
     
     
         13 . The method set forth in  claim 12 , wherein said step of machining the second composition is further defined by machining a plurality of chamfers into the second composition 
     
     
         14 . The method set forth in  claim 1 , further including the step of machining the second composition to a length L to depth D ratio ranging from one to ten. 
     
     
         15 . The method set forth in  claim 1 , further including the step of machining the second composition to a maximum depth D of about 0.5 mm to 4 mm.