Casting compositions for manufacturing metal casting and methods of manufacturing thereof

Abstract

Disclosed herein is a method comprising disposing a casting composition within a sacrificial die; wherein internal features of the sacrificial die provide a replica of a desired casting; wherein the casting composition has a viscosity of about 1 to about 1,000 Pascal-seconds at room temperature when tested at a shear rate of up to 70 seconds −1 ; reacting the casting composition to form a gel matrix; removing the sacrificial die; extracting a solvent from the gel matrix to form a dried gel; and firing the dried gel to form a ceramic core. Disclosed herein too is a casting composition comprising a monomer and/or a polymer; and a metal and/or ceramic powder; wherein the casting composition has a viscosity of about 1 to about 1,000 Pascal-seconds at room temperature when tested at a shear rate of up to 70 seconds −1 and a flow index of less than 0.6.

1 . A method comprising:
 disposing a casting composition within a sacrificial die; wherein internal features of the sacrificial die provide a replica of a desired casting; wherein the casting composition has a viscosity of about 1 to about 1,000 Pascal-seconds at room temperature when tested at a shear rate of up to 70 seconds −1 ;   reacting the casting composition to form a gel matrix;   removing the sacrificial die;   extracting a solvent from the gel matrix to form a dried gel; and   firing the dried gel to form a ceramic core.   
   
   
       2 . The method of  claim 1 , further comprising using the ceramic core to mold castings. 
   
   
       3 . The method of  claim 1 , wherein the internal features of the sacrificial die provide a replica of a turbine component. 
   
   
       4 . The method of  claim 1 , wherein external features of the sacrificial die provide a replica of a turbine component. 
   
   
       5 . The method of  claim 3 , wherein the turbine component is a stationary or rotating airfoil. 
   
   
       6 . The method of  claim 3 , wherein the turbine component is a seal, a shroud or a splitter. 
   
   
       7 . The method of  claim 1 , wherein the casting composition comprises a monomer and/or a polymer, a metal or ceramic powder and a solvent. 
   
   
       8 . The method of  claim 7 , wherein the monomer and/or polymer has a hydride functional group and is selected from the group consisting of:
 a polyfunctional hydride siloxane of formula:   
     
       
         
         
             
             
         
       
     
     wherein R is a monovalent hydrocarbon, R′″ is a monovalent hydrocarbon or hydrogen, and a and b a=0 to 20, inclusive, and b=1 to 80, inclusive, wherein a and b are selected to provide a fluid with maximum viscosity of 1 Pascal-second.
 an alkyl/hydride cyclosiloxane of formula:
   [HRSiO] x,    
 
 
     wherein x is an integer 3 to 18 inclusive,
 a functional hydride siloxane of formula: 
 
     
       
         
         
             
             
         
       
     
     wherein a ratio of the sum of (c+d+e+g)/f is ≧2,
 a terminal hydride siloxane of formula: 
 
     
       
         
         
             
             
         
       
     
     wherein n=0 to 100, and
 mixtures thereof. 
 
   
   
       9 . The method of  claim 8 , wherein the monomers and/or polymer comprises siloxanes that have a formula of: 
     
       
         
         
             
             
         
       
     
     wherein R 1 , R 2 , and R 3  each independently comprise hydrogen or a monovalent hydrocarbon radical, X a divalent hydrocarbon radical, and a is a whole number having a value between 0 and 8, inclusive. 
   
   
       10 . The method of  claim 7 , wherein the monomer and/or polymer has an alkenyl functional group and is selected from the group consisting of:
 a polyfunctional siloxane of formula:   
     
       
         
         
             
             
         
       
     
     wherein R is a monovalent hydrocarbon, R′ is an alkenyl radical, R″ is a monovalent hydrocarbon or an alkenyl radical, a=0 to 20, inclusive, and b=1 to 80, inclusive, wherein a and b are selected to provide a fluid with a maximum viscosity of 1 Pascal-second,
 a cyclic alkyl/alkenyl siloxane of formula:
   [RR′SiO] x,    
 
 
     wherein R and R′ are as previously defined; wherein x is an integer 3 to 18 inclusive
 an unsaturated siloxane of formula: 
 
     
       
         
         
             
             
         
       
     
     wherein R, R′, and R″ are as previously defined. Preferably, the ratio of the sum of (c+d+e+g)/f is ≧2;
 and mixtures thereof. 
 
   
   
       11 . The method of  claim 7 , wherein the monomer comprises acrylic acid, methacrylamide, methacrylic acid, hydroxymethylacrylamide, n-metholoylacrylamide, N,N′-methylenebisacrylamide, methoxy (polyethylene glycol) monomethacrylate, n-vinyl pyrrolidone, acrylamide, alkyl-acrylamide, alkyl-methacrylamide, alkyl-acrylate, alkyl-methacrylate, dimethyl aminoethyl methacrylate, dimethyl aminopropyl methacrylamide, hydroxy-alkyl acrylamide, hydroxy-alkyl methacrylamide, hydroxy-alkyl acrylate, hydroxy-alkyl methacrylate, methacrylatoethyl trimethyl ammonium chloride, methacrylamidopropyl trimethyl ammonium chloride, p-styrene sulfonic acid, p-styrene sulfonic acid salts, or a combination comprising at least one of the aforementioned monomers. 
   
   
       12 . The method of  claim 7 , wherein the monomer comprises hydroxymethylacrylamide. 
   
   
       13 . The method of  claim 7 , wherein the metallic or ceramic powders have particle sizes of less than or equal to about 1,200 nanometers. 
   
   
       14 . The method of  claim 7 , wherein the metallic or ceramic powders have particle sizes greater than 1200 nanometers. 
   
   
       15 . The method of  claim 7 , wherein the solvent is water. 
   
   
       16 . An article manufactured by the method of  claim 1 . 
   
   
       17 . The article of  claim 16 , wherein the article is a turbine component. 
   
   
       18 . A casting composition comprising:
 a monomer and/or a polymer; and   a metal and/or ceramic powder; wherein the casting composition has a viscosity of about 1 to about 1,000 Pascal-seconds at room temperature when tested at a shear rate of up to 70 seconds −1  and a flow index of less than 0.6.   
   
   
       19 . The casting composition of  claim 18 , wherein the monomer and/or polymer has a hydride functional group and is selected from the group consisting of:
 a polyfunctional hydride siloxane of formula:   
     
       
         
         
             
             
         
       
     
     wherein R is a monovalent hydrocarbon, R′″ is a monovalent hydrocarbon or hydrogen, and a and b a=0 to 20, inclusive, and b=1 to 80, inclusive, wherein a and b are selected to provide a fluid with maximum viscosity of 1 Pascal-second, an alkyl/hydride cyclosiloxanes of formula:
   [HRSiO] x,    
 
     wherein x is an integer 3 to 18 inclusive,
 a functional hydride siloxanes of formula: 
 
     
       
         
         
             
             
         
       
     
     wherein a ratio of the sum of (c+d+e+g)/f is ≧2,
 a terminal hydride siloxane of formula: 
 
     
       
         
         
             
             
         
       
     
     wherein n=0 to 100, and
 mixtures thereof. 
 
   
   
       20 . The casting composition of  claim 18 , wherein the monomers and/or polymer comprises siloxanes that have a formula of: 
     
       
         
         
             
             
         
       
     
     wherein R 1 , R 2 , and R 3  each independently comprise hydrogen or a monovalent hydrocarbon radical, X a divalent hydrocarbon radical, and a is a whole number having a value between 0 and 8, inclusive. 
   
   
       21 . The casting composition of  claim 18 , wherein the monomer and/or polymer has an alkenyl functional group and is selected from the group consisting of:
 polyfunctional siloxanes of formula:   
     
       
         
         
             
             
         
       
     
     wherein R is a monovalent hydrocarbon, R′ is an alkenyl radical, R″ is a monovalent hydrocarbon or an alkenyl radical, a=0 to 20, inclusive, and b=1 to 80, inclusive, wherein a and b are selected to provide a fluid with a maximum viscosity of 1 Pascal-second,
 a cyclic alkyl/alkenyl siloxane of formula:
   [RR′SiO] x,    
 
 
     wherein R and R′ are as previously defined; wherein x is an integer 3 to 18 inclusive
 an unsaturated siloxane of formula: 
 
     
       
         
         
             
             
         
       
     
     wherein R, R′, and R″ are as previously defined. Preferably, the ratio of the sum of (c+d+e+g)/f is ≧2;
 and mixtures thereof. 
 
   
   
       22 . The casting composition of  claim 18 , wherein the monomer comprises acrylic acid, methacrylamide, methacrylic acid, hydroxymethylacrylamide, n-metholoylacrylamide, N,N′-methylenebisacrylamide, methoxy (polyethylene glycol) monomethacrylate, n-vinyl pyrrolidone, acrylamide, alkyl-acrylamide, alkyl-methacrylamide, alkyl-acrylate, alkyl-methacrylate, dimethyl aminoethyl methacrylate, dimethyl aminopropyl methacrylamide, hydroxy-alkyl acrylamide, hydroxy-alkyl methacrylamide, hydroxy-alkyl acrylate, hydroxy-alkyl methacrylate, methacrylatoethyl trimethyl ammonium chloride, methacrylamidopropyl trimethyl ammonium chloride, p-styrene sulfonic acid, p-styrene sulfonic acid salts, or a combination comprising at least one of the aforementioned monomers.