Quasi self-destructive core for investment casting

Abstract

A composite core for forming a passage in an investment casting mold is provided including a generally hollow structural element. The structural element is configured to deform when a force is applied to an end thereof. A rigid shell element is formed about the structural element. The shell element extends beyond both an interior surface and an exterior surface of the structural element. The shell element is configured to shatter when the structural element deforms.

1 . A composite core positioned within an investment casting mold to form a passage, comprising:
 a hollow structural element configured to deform when a force is applied to an end thereof; and   a rigid shell element including a plurality of layers of slurry having particles of varying sizes formed about the structural element, the shell element extending beyond from an interior surface and to an exterior surface of the structural element such that the composite core has a hollow interior extending to adjacent the interior surface of the structural element, the shell element being configured to shatter when the structural element deforms.   
     
     
         2 . The composite core according to  claim 1 , wherein the rigid shell element is integrally formed with the structural element. 
     
     
         3 . The composite core according to  claim 1 , wherein the structural element comprises a coiled wire. 
     
     
         4 . The composite core according to  claim 1 , wherein a material of the structural element is substantially identical to a material of a component to be formed from the investment casting mold. 
     
     
         5 . The composite core according to  claim 1 , wherein the structural element is generally the same size as the passage being formed. 
     
     
         6 . The composite core according to  claim 1 , wherein the shell element is formed by curing the layers of slurry to form the rigid shell element. 
     
     
         7 . The composite core according to  claim 6 , wherein a material of the slurry is substantially identical to a material of the investment casting mold. 
     
     
         8 . The composite core according to  claim 6 , wherein the material of the slurry is ceramic. 
     
     
         9 . The composite core according to  claim 6 , further comprising:
 a core element positioned adjacent an interior surface of the structural element, the core element being configured to melt when heat is applied during formation of the rigid shell element such that the structural element retains the general shape of the core element.   
     
     
         10 . (canceled) 
     
     
         11 . The composite core according to  claim 9 , wherein the core element is a wax element. 
     
     
         12 . The composite core according to  claim 9 , wherein the core element is a metallic mesh or foil. 
     
     
         13 . The composite core according to  claim 12 , wherein the core element is coupled to the interior surface of the structural element. 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . A method for manufacturing a composite core for forming a passage in an investment casting mold, comprising:
 forming a generally hollow structural element configured to deform when a force is applied to an end thereof; and   forming a rigid shell element about the structural element, the shell element extending beyond an interior surface and an exterior surface of the structural element and being configured to shatter when the structural element deforms.   
     
     
         18 . The method according to  claim 17 , wherein the hollow structural element is formed about a core element. 
     
     
         19 . The method according to  claim 18 , wherein the rigid shell is formed by layering slurry particles of various sizes about the structural element. 
     
     
         20 . The method according to  claim 18 , wherein heat is applied to the composite core to harden the slurry particles and to melt the core element. 
     
     
         21 . A method for forming a passage in a cast component, comprising:
 arranging a composite core into an interior of a mold, the composite core including:
 a generally hollow structural element configured to deform when a force is applied to an end thereof; and 
 a rigid shell formed about the structural element, the shell element extending beyond an interior surface and an exterior surface of the structural element, wherein the shell element is configured to shatter when the structural element deforms; 
   pouring material of the component into the mold;   curing the material to form the component; and   applying a force to an exposed portion of the composite core such that the composite core deforms inside the component.   
     
     
         22 . (canceled)