Crucible and extrinsic facecoat compositions and methods for melting titanium and titanium aluminide alloys

Patent metadata

Field	Value
Publication number	US-9803923-B2
Application number	US-201514628423-A
Country	US
Kind code	B2
Filing date	Feb 23, 2015
Priority date	Dec 4, 2012
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

Crucible compositions and methods of using the crucible compositions to melt titanium and titanium alloys. More specifically, crucible compositions having extrinsic facecoats comprising a rare earth oxide that are effective for melting titanium and titanium alloys for use in casting titanium-containing articles. Further embodiments are titanium-containing articles made from the titanium and titanium alloys melted in the crucible compositions. Another embodiment is a crucible curing device and methods of use thereof.

First claim

The invention claimed is:

1. A method for forming a crucible for melting titanium and titanium alloys useful in making a titanium-containing article, said method comprising:
combining calcium aluminate cement with a liquid to produce a first slurry, wherein the percentage of solids in the first slurry is within the range of about 60% to about 80% and the viscosity of the first slurry is within the range of about 50 centipoise to about 150 centipoise;
adding large-scale oxide particles greater than 50 microns in size into the first slurry to form a second slurry, wherein the percentage of solids in the second slurry is within the range of about 65% to about 900/%;
introducing the second slurry into a crucible mold cavity with a removable crucible cavity pattern inserted into the crucible mold cavity; and
allowing the second slurry to cure in the crucible mold cavity and around the removable crucible cavity pattern to form a crucible for use in melting titanium and titanium alloys with a wall that defines a thickness that does not vary by more than 30 percent throughout the crucible.

2. The method as recited in claim 1 , further comprising combining fine-scale alumina particles less than 10 microns in size with the calcium aluminate cement and the liquid to produce the first slurry.

3. The method as recited in claim 2 , wherein the fine-scale alumina particles include hollow alumina particles.

4. The method as recited in claim 1 , wherein the large-scale oxide particles are large-scale alumina particles.

5. The method as recited in claim 1 , wherein the calcium aluminate cement comprises calcium monoaluminate, calcium dialuminate, and mayenite.

6. The method as recited in claim 1 , wherein the calcium aluminate cement comprises more than about 30% by weight of the second slurry.

7. The method as recited in claim 1 , further comprising firing the formed crucible at a temperature of between about 600° C. and about 1650° C., and wherein the fired crucible includes a weight fraction of 0.15 to 0.8 of calcium monoaluminate and a weight fraction of 0.01 to 0.2 of mayenite.

8. The method as recited in claim 1 , wherein the percentage of solids in the second slurry is within the range of about 75% to about 900/%.

9. The method as recited in claim 1 , wherein the second slurry forms at least one extrinsic facecoat layer comprising a rare earth oxide, and wherein the cavity of the formed crucible is defined by an exposed surface of the at least one extrinsic facecoat layer.

10. The method as recited in claim 9 , wherein the second slurry further forms a bulk behind the at least one extrinsic facecoat layer, and wherein the bulk and the at least one extrinsic facecoat layer form the wall that defines a thickness that does not vary by more than 30 percent throughout the crucible.

11. The method as recited in claim 10 , further comprising incorporating a bonding layer between the at least one extrinsic facecoat layer and the bulk, said bonding layer comprising a fine-scale calcium aluminate cement having a particle size of less than 50 microns.

12. The method as recited in claim 11 , wherein the bulk, the at least one extrinsic facecoat layer and the bonding layer form the wall that defines a thickness that does not vary by more than 30 percent throughout the crucible.

13. The method of claim 1 , further comprising:
firing the formed crucible at a temperature between about 600° C. and about 1650° C., wherein the fired crucible includes a weight fraction of 0.15 to 0.8 of calcium monoaluminate and a weight fraction of 0.01 to 0.2 of mayenite.

14. A method for forming a crucible for melting titanium and titanium alloys, the method comprising:
introducing a slurry into a crucible mold cavity with a removable crucible cavity pattern inserted into the crucible mold cavity, wherein the slurry is formed by a combination of a) calcium aluminate cement with a liquid, wherein the percentage of solids in the combination is within the range of about 60% to about 80% and the viscosity of the combination is about 50 centipoise to about 150 centipoise, and b) large-scale oxide particles greater than 50 microns in size added to the combination to form the slurry; and
allowing the slurry to cure in the crucible mold cavity and around the removable crucible cavity pattern to form a crucible for use in melting titanium and titanium alloys with a wall that defines a thickness that does not vary by more than 30 percent throughout the crucible.

15. The method of claim 14 , wherein the combination further comprises fine-scale hollow alumina particles less than 10 microns in size.

16. The method of claim 14 , wherein the large-scale oxide particles are large-scale alumina particles.

17. The method of claim 14 , wherein the calcium aluminate cement comprises calcium monoaluminate, calcium dialuminate, and mayenite.

18. The method of claim 14 , wherein the calcium aluminate cement comprises more than about 30% by weight of the slurry.

19. The method of claim 14 , wherein the slurry forms at least one extrinsic facecoat layer comprising a rare earth oxide, the cavity of the formed crucible is defined by an exposed surface of the at least one extrinsic facecoat layer, the slurry further forms a bulk behind the at least one extrinsic facecoat layer, and the bulk and the at least one extrinsic facecoat layer form the wall that defines a thickness that does not vary by more than 30 percent throughout the crucible.

20. The method of claim 19 , further comprising:
incorporating a bonding layer between the at least one extrinsic facecoat layer and the bulk, the bonding layer comprising a fine-scale calcium aluminate cement having a particle size of less than 50 microns.

Assignees

• Gen Electric

Inventors

• Bewlay Bernard Patrick
• Bancheri Stephen Francis
• Mckiever Joan
• Ellis Brian Michael

Classifications

• F27B14/10 Primary

  Crucibles · CPC title

• B28B7/28

  Cores; Mandrels {(B28B1/44 takes precedence; of special materials in general B28B7/34; cores for making blind holes in situ E04G15/04; for making recesses E04G15/06)} · CPC title

• F27B2014/104

  Crucible linings · CPC title

• F27D1/0006

  Linings or walls formed from bricks or layers with a particular composition or specific characteristics · CPC title

• B28B7/0002

  Auxiliary parts or elements of the mould · CPC title