Investment cast article and method of production thereof

• US 20070240845A1
• Filed: 04/18/2006
• Published: 10/18/2007
• Est. Priority Date: 04/18/2006
• Status: Abandoned Application

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Sexton, Brendan, Graham, Stephen
• Application Number:
  US11/406,176
• Publication Number:
  US 20070240845A1
• Time in Patent Office: Days
• US Class Current: 164/516
• CPC Class Codes: B22C 9/04 Use of lost patterns
• CPC Class Codes: F05B 2230/21 by casting

Abstract

A method for manufacturing an investment cast article is disclosed. The method comprises positioning an insert relative to a sacrificial form, the insert comprising a first portion and a second portion, the first portion being disposed inside the sacrificial form and the second portion being disposed outside the sacrificial form. The sacrificial form and the second portion of the insert are coated with a material, forming a shell surrounding the sacrificial form and the second portion of the insert. The sacrificial form is evacuated from the shell, followed by introducing molten metal into the evacuated shell, thereby providing a metal form, and resulting in the first portion of the insert being disposed and bonded inside the metal form. The shell is removed from the metal form and the second portion of the insert, thereby resulting in the metal form with the first portion of the insert disposed and bonded therein.

Claims

1. A method for manufacturing an investment cast article, the method comprising:

positioning an insert relative to a sacrificial form, the insert comprising a first portion and a second portion, the first portion being disposed inside the sacrificial form and the second portion being disposed outside the sacrificial form;

coating the sacrificial form and the second portion of the insert with a material, the material forming a shell surrounding the sacrificial form and the second portion of the insert;

evacuating the sacrificial form from the shell;

introducing molten metal into the evacuated shell, thereby providing a metal form, and resulting in the first portion of the insert being disposed and bonded inside the metal form; and

removing the shell from the metal form and the second portion of the insert, thereby resulting in the metal form with the first portion of the insert disposed and bonded therein.

2. The method of claim 1, wherein the positioning the insert further comprises:

positioning the insert relative to a die having a cavity larger than the first portion of the insert, such that the first portion of the insert is disposed inside the cavity, and the second portion of the insert is disposed outside the cavity and captivated by the die;

introducing molten filler into the cavity to create the sacrificial form, resulting in the filler being bonded to the first portion of the insert; and

removing the sacrificial form and the insert from the die, the second portion of the insert disposed outside the sacrificial form, thereby providing the sacrificial form and the insert.

3. The method of claim 1, further comprising:

machining the second portion of the insert subsequent to the removing.

4. The method of claim 1, wherein:

the introducing molten metal occurs while the shell and the molten metal are subject to a vacuum.

5. The method of claim 1, wherein the positioning comprises:

positioning the insert comprising mechanical retention features.

6. The method of claim 1, wherein the manufacturing comprises:

manufacturing an investment cast gas turbine airfoil.

7. The method of claim 6, wherein:

the positioning comprises positioning the insert made from a material to provide characteristics pertinent to localized application needs of the gas turbine airfoil including at least one of temperature, oxidation, wear, and corrosion resistance;

the positioning comprises positioning the insert comprising a plating made from platinum, palladium, or a combination thereof; and

the introducing comprises introducing an alloy of nickel, cobalt, or a combination thereof.

8. The method of claim 6, wherein the positioning further comprises:

positioning the insert relative to a die having a cavity larger than the first portion of the insert, such that the first portion of the insert is disposed inside the cavity, and the second portion of the insert is disposed outside the cavity and captivated by the die;

introducing molten filler into the cavity to create the sacrificial form, resulting in the filler being bonded to the first portion of the insert; and

removing the sacrificial form and the insert from the die, the second portion of the insert disposed outside the sacrificial form, thereby providing the sacrificial form and the insert.

9. The method of claim 8, wherein:

the die cavity has a plurality of positions that correspond to an airfoil tip, an airfoil leading edge, an airfoil trailing edge, airfoil tip shroud contact surfaces, airfoil angle wings, an airfoil platform edge, and an airfoil tip shroud edge; and

the positioning comprises positioning one or more inserts at the positions of the die cavity corresponding to one or more of the airfoil tip, the airfoil leading edge, the airfoil trailing edge, the airfoil tip shroud contact surfaces, the airfoil angle wings, the airfoil platform edge, and the airfoil tip shroud edge.

10. The method of claim 6, further comprising:

machining one or more of the second portion of the insert and the metal form.

11. A gas turbine airfoil produced according to the method of:

positioning an insert relative to a sacrificial form, the insert comprising a first portion and a second portion, the first portion being disposed inside the sacrificial form and the second portion being disposed outside the sacrificial form;

coating the sacrificial form and the second portion of the insert with a material, the material forming a shell surrounding the sacrificial form and the second portion of the insert;

evacuating the sacrificial form from the shell;

introducing molten metal into the evacuated shell, thereby providing a metal form, and resulting in the first portion of the insert being disposed and bonded inside the metal form; and

removing the shell from the metal form and the second portion of the insert, thereby resulting in the metal form with the first portion of the insert disposed and bonded therein;

machining one or more of the second portion of the insert and the metal form, thereby providing the turbine airfoil.

12. The gas turbine airfoil of claim 11, wherein:

the insert comprises mechanical retention features.

13. The gas turbine airfoil of claim 11, wherein:

the first portion of the machined insert is retained by one or more of a mechanical bond and a metallurgical bond.

14. The gas turbine airfoil of claim 11, wherein:

the airfoil is made from an alloy of nickel, cobalt, or a combination thereof; and

the insert is made from a material to provide characteristics pertinent to localized application needs of the gas turbine airfoil including at least one of temperature, oxidation, wear, and corrosion resistance.

15. The gas turbine airfoil of claim 11, comprising:

an airfoil tip, an airfoil leading edge, an airfoil trailing edge, airfoil tip shroud contact surfaces, airfoil angle wings, an airfoil platform edge, and an airfoil tip shroud edge;

one or more machined inserts at one or more of the following locations of the airfoil;

the airfoil tip;

the airfoil leading edge;

the airfoil trailing edge;

the airfoil tip shroud contact surfaces;

the airfoil angle wings;

the airfoil platform edge; and

the airfoil tip shroud edge.

16. The gas turbine airfoil of claim 11 wherein:

the melting temperature of the insert is greater than the melting temperature of the metal form.