Investment casting method and cores and dies used therein

Abstract

A method for making an article by an investment casting process is presented, along with a method for making casting cores, the casting cores made by this method, and dies for making such cores. The method for making a component comprises providing a single-piece sacrificial die, the die comprising at least one internal cavity; introducing a ceramic slurry into the at least one cavity of the die, the slurry comprising a ceramic and a carrier fluid; curing the slurry to form a ceramic casting core; removing the sacrificial die by exposing the die to an environment adapted to destroy the die while leaving the ceramic casting core intact; and performing an investment casting process using the ceramic casting core as part of a mold-core assembly to form the component.

1 . A method for making a component, said method comprising: 
 providing a single-piece sacrificial die, said die comprising at least one internal cavity;    introducing a ceramic slurry into said at least one cavity of said die, said slurry comprising a ceramic and a carrier fluid;    curing said slurry to form a ceramic casting core;    removing said sacrificial die by exposing said die to an environment adapted to destroy said die while leaving said ceramic casting core intact; and    performing an investment casting process using said ceramic casting core as part of a mold-core assembly to form said component.    
     
     
         2 . The method of  claim 1 , wherein providing said single-piece sacrificial die comprises producing said die by at least one additive layer manufacturing process.  
     
     
         3 . The method of  claim 2 , wherein said additive layer manufacturing process comprises stereolithography.  
     
     
         4 . The method of  claim 2 , wherein said additive layer manufacturing process comprises at least one of micro-pen deposition, selective laser sintering, and laser wire deposition.  
     
     
         5 . The method of  claim 1 , wherein said die comprises at least one sacrificial material selected from the group consisting of an epoxy, a silicone, and a metal.  
     
     
         6 . The method of  claim 1 , wherein said ceramic slurry comprises at least one of alumina, yttria, ceria, zirconia, magnesia, and calcia.  
     
     
         7 . The method of  claim 1 , wherein said component comprises an external wall and at least one internal wall disposed in a spaced-apart relationship with said external wall.  
     
     
         8 . The method of  claim 1 , wherein introducing said slurry comprises operating an injection molding apparatus to introduce said slurry into said cavity of said die.  
     
     
         9 . The method of  claim 1 , wherein curing comprises heating said slurry to evaporate said carrier fluid.  
     
     
         10 . The method of  claim 1 , wherein removing said die comprises heating said die.  
     
     
         11 . The method of  claim 1 , wherein removing said die comprises dissolving said die in a solvent.  
     
     
         12 . The method of  claim 1 , wherein removing said die comprises chemically removing said die.  
     
     
         13 . The method of  claim 1 , wherein said component is a component of a turbine assembly.  
     
     
         14 . The method of  claim 13 , wherein said component comprises one of a vane and a blade.  
     
     
         15 . The method of  claim 14 , wherein said component comprises an external wall and at least one internal wall disposed in a spaced-apart relationship with said external wall.  
     
     
         16 . The method of  claim 14 , wherein said component comprises at least one internal cooling passage.  
     
     
         17 . The method of  claim 16 , wherein said at least one passage further comprises turbulators.  
     
     
         18 . A method for making a component for a turbine assembly, said method comprising: 
 using a stereolithography process to provide a single-piece sacrificial die, said die comprising at least one internal cavity;    introducing a ceramic slurry into said at least one cavity of said die, said slurry comprising a ceramic and a carrier fluid;    curing said slurry to form a ceramic casting core;    removing said sacrificial die by exposing said die to an environment adapted to destroy said die while leaving said ceramic casting core intact; and    performing an investment casting process using said ceramic casting core as part of a mold-core assembly to form said component;    wherein said component comprises an external wall and at least one internal wall disposed in a spaced-apart relationship with said external wall, and further comprises at least one cooling passage disposed between said external wall and said internal wall.    
     
     
         19 . A method for making a casting core, comprising: 
 manufacturing a single-piece sacrificial die using an additive layer manufacturing method, said die comprising at least one internal cavity;    introducing a ceramic slurry into said cavity of said die, said slurry comprising a ceramic and a carrier fluid;    curing said slurry to form a ceramic casting core; and    removing said sacrificial die by exposing said die to an environment adapted to destroy said die while leaving said ceramic casting core intact.    
     
     
         20 . The method of  claim 19 , wherein said additive layer manufacturing process comprises stereolithography.  
     
     
         21 . The method of  claim 19 , wherein said additive layer manufacturing process comprises at least one of micro-pen deposition, selective laser sintering, and laser wire deposition.  
     
     
         22 . The method of  claim 19 , wherein said die comprises at least one sacrificial material selected from the group consisting of an epoxy, a silicone, and a metal.  
     
     
         23 . The method of  claim 19 , wherein introducing said slurry comprises operating an injection molding apparatus to introduce said slurry into said cavity of said die.  
     
     
         24 . The method of  claim 19 , wherein removing said die comprises at least one of heating said die, dissolving said die in a solvent, and chemically removing said die.  
     
     
         25 . The method of  claim 19 , wherein said core is configured to form internal passages in an investment cast article.  
     
     
         26 . The method of  claim 25 , wherein said article comprises an external wall and at least one internal wall disposed in a spaced-apart relationship with said external wall, and further comprises at least one cooling passage disposed between said external wall and said internal wall.  
     
     
         27 . The method of  claim 25 , wherein said article is a component of a turbine assembly.  
     
     
         28 . A casting core manufactured by the method of  claim 19 .  
     
     
         29 . A die for making a casting core, comprising: 
 a single piece structure comprising at least one cavity, said cavity configured to correspond to a desired configuration of at least one internal cooling circuit of a gas turbine component;    wherein said structure comprises a material capable of being selectively removed from a ceramic casting core when said ceramic casting core is disposed in said at least one cavity.    
     
     
         30 . The die of  claim 29 , wherein said structure comprises a structure assembled in an additive layer manufacturing process.  
     
     
         31 . The die of  claim 30 , wherein said additive layer manufacturing process comprises stereolithography.  
     
     
         32 . The die of  claim 30 , wherein said material comprises at least one sacrificial material selected from the group consisting of an epoxy, a silicone, and a metal.