Composite mold with fugitive metal backup

Abstract

Composite mold for use in casting a metal or alloy includes an inner mold region that includes a mold cavity and a fugitive metallic outer backup mold region residing on the inner mold region, wherein the metallic material of the backup mold region has such a melting temperature that the backup mold region melts from the inner mold region after the molten metal or alloy is cast and at least partially solidified in the mold. The inner mold region can comprise a non-metallic refractory or ceramic shell mold, while the backup mold region can comprise tin or other relatively low melting point metal or alloy.

1 . Composite mold for casting a metal or alloy, comprising an inner mold region having a mold cavity and a fugitive metallic outer backup mold region residing on the inner mold region, wherein metallic material of the backup mold region has such a melting temperature that the backup mold region melts from the inner mold region after the molten metal or alloy is cast and at least partially solidified.  
   
   
       2 . The mold of  claim 1  wherein the inner mold region comprises a shell mold.  
   
   
       3 . The mold of  claim 2  wherein the shell mold has a wall thickness of about 0.1 inch or less.  
   
   
       4 . The mold of  claim 1  wherein the backup mold region comprises a metal or alloy that melts at a temperature of about 1300 degrees F. or below.  
   
   
       5 . The mold of  claim 4  wherein the backup mold region comprises a metallic material comprising tin, indium, bismuth, lead, aluminum, or zinc, or alloys thereof one with another or with other metals.  
   
   
       6 . The mold of  claim 1  wherein the backup mold region comprises a metal or alloy that melts at a temperature of at least 500 degrees F. below that of the metal or alloy to be cast in the mold.  
   
   
       7 . The mold of  claim 1  wherein the backup mold region is cast and solidified in-situ on the inner mold region.  
   
   
       8 . Composite mold for casting a metal or alloy, comprising a ceramic inner shell mold region having a mold cavity and a fugitive metallic outer backup mold region residing on the inner shell mold region, wherein metallic material of the backup mold region has such a melting temperature less than about 1300 degrees F.  
   
   
       9 . The mold of  claim 8  wherein the inner shell mold region has a wall thickness of about 0.1 inch or less.  
   
   
       10 . The mold of  claim 8  wherein the backup mold region comprises a metallic material comprising tin, indium, bismuth, lead, aluminum, or zinc, or alloys thereof one with another or with other metals.  
   
   
       11 . The mold of  claim 8  wherein the backup mold region is cast and solidified in-situ on the inner mold region.  
   
   
       12 . Method of casting, comprising introducing a molten metal or alloy into a mold cavity of a composite mold having an inner mold region that includes said mold cavity and a fugitive metallic outer backup mold region residing on the inner mold region, and melting the backup mold region from the inner mold region after the molten metal or alloy is cast and at least partially solidified.  
   
   
       13 . The method of  claim 12  wherein the inner mold region comprises a shell mold.  
   
   
       14 . The method of  claim 13  wherein the shell mold has a wall thickness of about 0.1 inch or less.  
   
   
       15 . The method of  claim 12  wherein the backup mold region comprises a metal or alloy that melts at a temperature of about 1300 degrees F. or below.  
   
   
       16 . The method of  claim 15  wherein the backup mold region comprises a metallic material comprising tin, indium, bismuth, lead, aluminum, or zinc, or alloys thereof one with another or with other metals.  
   
   
       17 . The method of  claim 12  including casting and solidifying the backup mold region in-situ on the inner mold region before introducing the molten metal or alloy.  
   
   
       18 . The method of  claim 12  wherein the molten metal or alloy is introduced under pressure into the mold cavity.  
   
   
       19 . The method of  claim 18  wherein the molten metal or alloy is die cast into the mold cavity.  
   
   
       20 . The method of  claim 12  wherein the molten metal or alloy is gravity cast into the mold cavity.  
   
   
       21 . Method of casting titanium aluminide, comprising introducing molten titanium aluminide into a mold cavity of a composite mold having a ceramic inner shell mold region that includes said mold cavity and a fugitive metallic outer backup mold region residing on the inner shell mold region, and melting the backup mold region away from the inner shell mold region after the molten titanium aluminide is cast and at least partially solidified.  
   
   
       22 . The method of  claim 21  wherein the inner shell mold has a wall thickness of about 0.1 inch or less.  
   
   
       23 . The method of  claim 23  wherein the backup mold region comprises a metal or alloy that melts at a temperature of about 1300 degrees F. or below.  
   
   
       24 . The method of  claim 23  wherein the backup mold region comprises a metallic material comprising tin, indium, bismuth, lead, aluminum, or zinc, or alloys thereof one with another or with other metals.  
   
   
       25 . Method of making a casting mold, comprising forming a non-metallic refractory or ceramic inner shell mold region and forming a fugitive metallic outer backup mold region in-situ on the inner shell mold region.  
   
   
       26 . The method of  claim 25  wherein the backup mold region is cast and solidified in-situ on the inner mold region.