Countergravity casting apparatus and desulfurization methods

Patent metadata

Field	Value
Publication number	US-11433452-B2
Application number	US-201916599646-A
Country	US
Kind code	B2
Filing date	Oct 11, 2019
Priority date	Oct 27, 2017
Publication date	Sep 6, 2022
Grant date	Sep 6, 2022

Abstract

An apparatus for countergravity casting a metallic has: a crucible for holding melted metallic material; a casting chamber for containing a mold; a fill tube capable of extending into the crucible to communicate melted metallic material to the casting chamber; and a gas source coupled to a headspace of the melting vessel to allow the gas source to pressurize said headspace to establish a pressure differential to force the melted metallic material upwardly through said fill tube into the mold. Added sulfur-gettering particles subsequently filtered or sulfur-gettering material removes sulfur from the melted metallic material.

First claim

What is claimed is:

1. An apparatus for countergravity casting a metallic material, the apparatus comprising:
a melting vessel;
a casting chamber containing a mold;
a fill tube capable of extending into the melting vessel to communicate melted metallic material to the casting chamber; and
a gas source coupled to a headspace of the melting vessel to allow the gas source to pressurize said headspace to establish a pressure differential to force the melted metallic material upwardly through said fill tube into said mold,
wherein at least one of the fill tube and mold has a substrate and a surface layer on the substrate, the surface layer of a sulfur-gettering material of greater sulfur-gettering ability than alumina and zirconia.

2. The apparatus of claim 1 wherein:
the sulfur gettering ability is at least that of 20 weight percent MgO in ZrO 2 .

3. The apparatus of claim 1 wherein:
the mold has a cavity shaped to form a gas turbine engine component.

4. The apparatus of claim 1 wherein:
the sulfur-gettering material comprises CaO.

5. The apparatus of claim 4 wherein:
the surface layer is along the mold.

6. The apparatus of claim 1 wherein:
the surface layer is at least 50 weight percent MgO.

7. The apparatus of claim 1 wherein:
the surface layer is along the mold.

8. The apparatus of claim 7 wherein:
the substrate is an alumina or zirconia substrate; and
a thickness of the surface layer is 0.25 mm to 2.0 mm.

9. The apparatus of claim 8 wherein:
the surface layer has sulfur gettering ability at least that of 20 weight percent MgO in ZrO 2 .

10. The apparatus of claim 8 wherein:
the sulfur-gettering material comprises CaO.

11. The apparatus of claim 1 wherein:
the sulfur-gettering material comprises at least one of MgO and CaO.

12. The apparatus of claim 1 , wherein:
the surface layer comprises at least 50 weight percent material selected from the group consisting of:
MgO;
CaO,
LaO;
Y 2 O 3 ;
other rare earth element oxide(s) with greater sulfur affinity than ZrO 2 ; and
combinations thereof.

13. The apparatus of claim 1 wherein:
the surface layer is along the fill tube.

14. The apparatus of claim 13 wherein:
a thickness of the surface layer is 0.25 mm to 2.0 mm.

15. The apparatus of claim 13 wherein:
the sulfur-gettering material comprises LaO.

16. The apparatus of claim 15 wherein:
the surface layer comprises at least 50 weight percent LaO.

17. The apparatus of claim 16 wherein:
the substrate is an alumina or zirconia substrate.

18. The apparatus of claim 1 wherein:
the substrate is an alumina or zirconia substrate; and
a thickness of the surface layer is 0.25 mm to 2.0 mm.

19. A method for using the apparatus of claim 1 , the method comprising:
melting a nickel-based superalloy in a melting crucible;
disposing the casting mold under subambient pressure on a mold base with a fill tube of said mold extending through an opening in said base;
relatively moving said melting crucible and said base to immerse an opening of said fill tube in the melted nickel-based superalloy in said melting crucible and to engage said melting crucible and said base with seal means therebetween such that a sealed gas pressurizable space is formed between the melted nickel-based superalloy and said base; and
gas pressurizing said space to establish a pressure differential on the melted nickel-based superalloy to force it upwardly through said fill tube into said casting mold, the melted nickel-based superalloy passing through the a filter,
wherein the melted nickel-based superalloy contacts the surface layer, the surface layer removing sulfur from the melted nickel-based superalloy.

20. An apparatus for countergravity casting a metallic material, the apparatus comprising:
a melting vessel;
a casting chamber containing a mold;
a fill tube capable of extending into the melting vessel to communicate melted metallic material to the casting chamber; and
a gas source coupled to a headspace of the melting vessel to allow the gas source to pressurize said headspace to establish a pressure differential to force the melted metallic material upwardly through said fill tube into said mold, wherein at least one of the melting vessel, fill tube, and mold has a substrate and a surface layer on the substrate, the surface layer of a sulfur-gettering material comprising CaO and the surface layer being of greater sulfur-gettering ability than each of a sulfur-gettering ability of alumina and a sulfur-gettering ability of zirconia.

21. The apparatus of claim 20 wherein:
the substrate is an alumina or zirconia substrate; and
a thickness of the surface layer is 0.25 mm to 2.0 mm.

Assignees

• Raytheon Tech Corp

Inventors

• Marcin Jr John J
• Cetel Alan D
• Bochiechio Mario P
• Clemens Reade R

Classifications

• B22D21/025

  Casting heavy metals with high melting point, i.e. 1000 - 1600 degrees C, e.g. Co 1490 degrees C, Ni 1450 degrees C, Mn 1240 degrees C, Cu 1083 degrees C · CPC title

• C22B9/02

  Refining by liquating, filtering, centrifuging, distilling, or supersonic wave action {including acoustic waves; (C22B9/003, C22B9/006, C22B9/05, C22B9/22 take precedence)} · CPC title

• B22D23/00

  Casting processes not provided for in groups B22D1/00 - B22D21/00 (making metallic powder by casting B22F9/08; alumino-thermic welding B23K23/00; remelting metals C22B9/16) · CPC title

• B22D18/04 Primary

  Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould · CPC title

• B22D1/00 Primary

  Treatment of fused masses in the ladle or the supply runners before casting {(for continuous casting B22D11/10; metallurgical processing, e.g. refining of iron or other metal C21, C22, C25C)} · CPC title