Soluble casting core for metal matrix composite components and method of producing thereof

Abstract

A process for manufacturing a soluble casting core for use in casting complex shaped metal matrix composite components. The soluble casting core is generated by a sequence of steps which provide a molten slurry mixture composed of an alkali metal salt such as sodium carbonate and a plurality of ceramic particulates such as magnesium oxide dispersed therein. After heating and mixing the slurry mixture is solidified in a mold pattern to form a casting core configured to generate a complex shaped component during a casting process. The soluble casting core is used for casting molten metal alloys therein, without failure of the casting surfaces and forming of a complex shaped metal matrix composite component. The soluble casting core is readily dissolved and separated from the soluble casting core by immersing the core mold in heated water and/or exposing to steam, without damage to the metal matrix composite component.

1 . A method of producing a soluble casting core for casting a complex shaped metal composite component, comprising the steps of: 
 (a) heating a slurry composed of a water soluble metal salt to form a molten slurry;    (b) mixing a plurality of ceramic particulates selected from a singular continuous size range of less than 150 microns, with sad molten slurry to form a molten slurry mixture;    (c) providing a mold pattern having a cavity therein and having a designed core shape substantially matching the complex shaped metal composite component, said step of providing including preheating said mold pattern to a selected temperature;    (d) pouring said molten slurry mixture Into said mold pattern;    (e) cooling said molten slurry mixture within said mold pattern, said step of cooling forming a solidified casting core having a plurality of casting surfaces configured in duplication of said designed core shape;    (f) removing sad solidified casting core from said mold pattern;    (g) pressure infiltrating molten metal into said solidified casting core, said step of pressure infiltrating including said molten metal being retained by said solidified casting core for a sufficient time for solidification of said molten metal forming a cast metal composite component;    (h) exposing said solidified casting core to heated liquid by immersing said casting core in said heated liquid; and    (i) dissolving said solidified casting core by continued exposure to heated liquid thereby releasing the metal composite component having said designed core shape.    
   
   
       2 . The method of  claim 1 , further comprising: 
 (ii) machining said solidified casting core following said step of removing, said step of machining providing substantially exact duplication of said plurality of casting surfaces in relation to said selected core shape; and    (iii) coating said plurality of casting surfaces of said solidified casting core with coating materials forming substantially impervious casting surfaces.    
   
   
       3 . The method of  claim 2  wherein said step of heating said slurry including a sodium carbonate compound maintained as said molten slurry.  
   
   
       4 . The method of  claim 3  wherein said step of mixing said plurality of ceramic particulates includes adding a plurality of magnesium oxide particulates having a powder size selected from said singular continuous size range of between about 5 microns to about 150 microns.  
   
   
       5 . The method of  claim 4  wherein said step of mixing further including said molten slurry mixture composed of sodium carbonate by weight percentage of between about 50% to about 97%, and mixing in said magnesium oxide particulates by weight percentage of between about 3% to about 50%.  
   
   
       6 . The method of  claim 1  wherein said step of providing said preheated mold pattern including said preheated mold pattern being composed of stainless steel or graphite and having at least one configuration having an internal void therein.  
   
   
       7 . The method of  claim 1  wherein said step of providing said mold pattern preheated to said selected temperature further including a step of preheating said mold pattern to a temperature selected from a range of between about 400° C. to about 650° C. before said step of pouring said molten slurry mixture into sad mold pattern.  
   
   
       8 . The method of  claim 1  wherein said step of providing said mold pattern preheated to said selected temperature further including a step of superheating said mold pattern to a temperature selected from a range of between about 850° C. to about 950° C. before said step of pouring said molten slurry mixture into said mold pattern.  
   
   
       9 . A process for manufacturing a casting core for casting a complex shaped metal composite component, comprising the steps of: 
 (a) heating a slurry composed of a water soluble metal salt to form a molten slurry;    (b) mixing a plurality of ceramic particulates selected from a continuous size range of less than about 140 microns with said molten slurry to form a molten slurry mixture;    (c) providing a mold pattern having a cavity therein and having a designed core shape substantially matching the complex shaped metal composite component, said step of providing including preheating said mold pattern to a selected temperature;    (d) pouring said molten slurry mixture into said mold pattern;    (e) cooling said molten slurry mixture within said mold pattern, said step of cooling forming a solidified water soluble casting core having a plurality of casting surfaces configured to match said designed core shape; and    (f) removing said solidified casting core from said mold pattern, whereby said solidified casting core is water soluble and configured for pressure casting the complex shaped metal composite component.    
   
   
       10 . The process of  claim 9 , further comprising: 
 (i) machining said solidified casting core following said step of removing, said step of machining providing exact duplication of said plurality of casting surfaces with said selected core shape;    (ii) coating said plurality of casting surfaces of said solidified casting core with coating materials forming substantially impermeable casting surfaces;    (iii) infiltrating molten metal into said solidified casting core, said step of infiltrating including said molten metal being retained by said solidified casting core until said molten metal is solidified in the cast metal composite component;    (iv) exposing said solidified casting core to superheated liquid; and    (v) dissolving said solidified casting core by continued exposing to superheated liquid thereby providing the metal composite component having said designed core shape.    
   
   
       11 . The process of  claim 9  wherein said step of heating said slurry composed of said water soluble metal salt including a sodium carbonate compound maintained in said molten slurry.  
   
   
       12 . The process of  claim 11  wherein said step of mixing said plurality of ceramic particulates includes selecting magnesium oxide particulates having a powder size selected from said continuous size range of between about 5 microns to about 140 microns.  
   
   
       13 . The process of  claim 12  wherein said step of mixing her including said molten slurry mixture composing said sodium carbonate compound by weight percentage of between about 50% to about 97%, and composing said magnesium oxide particulates by weight percentage of between about 3% to about 50%.  
   
   
       14 . The process of  claim 9  wherein said step of providing said mold pattern including said mold pattern being composed of stainless steel or graphite and having a complex shaped configuration having an internal void therein.  
   
   
       15 . The process of  claim 14  wherein said step of providing said mold pattern preheated to said selected temperature further including preheating said mold pattern to a temperature selected from a range of between about 400° C. to about 650° C. before said step of pouring said molten slurry mixture into said mold pattern.  
   
   
       16 . The process of  claim 14  wherein said step of providing said mold pattern preheated to said selected temperature further including a step of superheating said mold pattern to a temperature selected from a range of between about 850° C. to about 950° C. before said step of pouring said molten slurry mixture into said mold pattern.  
   
   
       17 . A casting core composed of soluble material for use in casting a complex shaped metal component, comprising: 
 a mold pattern composed of a water soluble metal salt having a plurality of ceramic particulates in a selected continuous size range dispersed throughout, said mold pattern being solidified in a designed core shape configured to substantially duplicate a complex shaped metal component;    whereby upon said solidified mold pattern being used to cast the complex shaped metal component, said solidified mold pattern is readily separated from the complex shaped metal component by dissolution in water.    
   
   
       18 . The casting core of  claim 17  wherein said water soluble metal salt includes a sodium carbonate compound composing between about 50% to about 97% by weight percentage of said solidified mold pattern.  
   
   
       19 . The casting core of  claim 18  wherein said plurality of ceramic particulates in a selected continuous size range includes a plurality of magnesium oxide particulates having a powder size selected from the range of between about 5 microns to about 150 microns, said plurality of magnesium oxide particulates being evenly disposed throughout said solidified mold pattern.  
   
   
       20 . The casting core of  claim 19  wherein said plurality of magnesium oxide particulates composing between about 3% to about 50% by weight percentage of said solidified mold pattern.  
   
   
       21 . The process of  claim 9 , wherein said solidified casting core includes: 
 water soluble metal salt composed of sodium carbonate in a weight percentage of about 50% to about 97%; and    ceramic particulates composed of magnesium oxide particulates in a weight percentage of about 3% to about 50%, said magnesium oxide particulates having a powder size selected in said selected continuous size range of between about 5 microns to about 140 microns.