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.

What is claimed is: 
     
         1 . A method for manufacturing a composite core for forming a passage in an investment casting mold comprising:
 arranging a core element adjacent an interior surface of a generally hollow structural element to form a preform;   layering slurry having particles of varying sizes about the structural element of the preform; and   applying heat to the preform.   
     
     
         2 . The method according to  claim 1 , wherein applying heat to the preform causes the slurry to cure into a rigid shell element. 
     
     
         3 . The method according to  claim 1 , wherein applying heat to the preform causes the core element to melt away from the structural element during the firing of the preform. 
     
     
         4 . The method according to  claim 1 , wherein the slurry extends from adjacent a surface of the core element to beyond an outer surface of the structural element. 
     
     
         5 . The method according to  claim 1 , wherein the slurry includes particles of varying sizes. 
     
     
         6 . The method according to  claim 1 , wherein a material of the structural element is substantially identical to a material of a component being formed in the investment casting mold. 
     
     
         7 . The method according to  claim 1 , wherein the structural element comprises a coiled wire. 
     
     
         8 . The method according to  claim 1 , wherein the structural element is the same size as the passage being formed. 
     
     
         9 . The method according to  claim 1 , wherein a material of the slurry is substantially identical to a material of the investment casting mold. 
     
     
         10 . The method according to  claim 1 , wherein the material of the slurry is ceramic. 
     
     
         11 . The method according to  claim 1 , wherein the core element is a metallic mesh or foil. 
     
     
         12 . The method according to  claim 1 , wherein the core element is a wax element. 
     
     
         13 . A method for forming a passage in a cast component comprising:
 arranging a composite core into an interior of a mold;   pouring material of the component into the mold;   curing the material to form the component;   applying a force to an exposed portion of the composite core such that the composite core deforms inside the component.   
     
     
         14 . The method according to  claim 13 , wherein the composite core includes a structural element and a rigid outer shell element formed about the structural element such that deformation of the structural element causes the shell element to break.