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Ceramic to metal joint assembly

Imported: 24 Feb '17 | Published: 06 Jan '04

Bjoern Schenk

USPTO - Utility Patents

Abstract

A joint assembly for coupling a ceramic member to a metal member is comprised of a ceramic shaft portion attached to the ceramic member; a slotted shrink fitter formed of a first metal and disposed around and in torque transmitting contact with the ceramic shaft portion to define a first interface surface therebetween; and a sleeve formed of a second metal disposed around and in torque transmitting contact with the shrink fitter to define a second interface surface therebetween. Either the shrink fitter or the sleeve attached to the metal member. The coefficient of thermal expansion of the second metal is relatively low compared to that of the first metal and the diameters of the first interface, (d

1), and the second interface, (d

2), are determined from the equation, d

1/d

2=(

c

1)/(

2

1) where

c,

1 and

2 are the coefficients of thermal expansion of the ceramic, the first metal and the second metal respectively. A compliant sleeve is disposed the ceramic shaft portion and the slotted shrink fitter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a portion of a gas turbine engine incorporating the joint assembly contemplated by the present invention as shown in FIG.

2.

FIG. 2 is a cutaway perspective view of the joint assembly contemplated by the present invention.

FIG. 3 is a cutaway perspective view of an alternative embodiment of the joint assembly contemplated by the present invention.

FIG. 4 is a front view of the joint assembly of FIGS. 2 and 3.

FIG. 5 is an enlarged view of one embodiment of an interface surface of the present invention.

FIG. 6 is an enlarged view of another embodiment of an interface surface of the present invention.

Claims

1. A joint assembly, comprising:

d

1

/d

2=(

c

1)/(

2

1),

where

c is the coefficient of thermal expansion of said ceramic shaft portion,

1 is the coefficient of thermal expansion of said first material, and

2 is the coefficient of thermal expansion of said second material.

2. The assembly of claim 1 wherein said torque transmitting contact is an interference fit.

3. The assembly of claim 1 wherein the coefficient of thermal expansion of said first material is greater than the coefficient of thermal expansion of said second material which is greater than the coefficient of thermal expansion of said ceramic shaft portion.

4. The assembly of claim 1 wherein the material of said ceramic shaft portion is selected from a group consisting of silicon nitride and silicon carbide.

5. The assembly of claim 1 wherein said shrink fitter is integral with said metal member.

6. The assembly of claim 1 wherein said shrink fitter has a plurality of circumferentially spaced apart, longitudinally extending slots, whereby during operation of the assembly, a width of each of the slots decreases to translate a hindered radial expansion displacement of said shrink fitter into circumferential displacement.

7. The assembly of claim 1 wherein said sleeve is integral with said metal member.

8. The assembly of claim 7 wherein said shrink fitter has a plurality of circumferentially spaced apart, longitudinally extending slots, whereby, during operation of the assembly, a width of each of the slots decreases to translate a hindered radial expansion displacement of said shrink fitter into circumferential displacement.

9. The assembly of claim 7 wherein said shrink fitter is comprised of a plurality parts circumferentially spaced apart to define a longitudinally extending gap between adjacent parts, whereby, during operation of the assembly, a width of each of the gaps decreases to translate a hindered radial expansion displacement of said shrink fitter into circumferential displacement.

10. The assembly of claim 1 wherein said solid lubricant is a noble metal.

11. The assembly of claim 10 wherein said solid lubricant is gold.

12. A joint assembly, comprising:

d

1

/d

2=(

c

1)/(

2

1),

where

c is the coefficient of thermal expansion of said ceramic shaft portion,

1 is the coefficient of thermal expansion of said first material, and

2 is the coefficient of thermal expansion of said second material.

13. The assembly of claim 12 wherein said torque transmitting contact is an interference fit.

14. The assembly of claim 12 wherein a coefficient of thermal expansion of said first material is greater than a coefficient of thermal expansion of said second material which is greater than a coefficient of thermal expansion of said ceramic shaft portion.

15. The assembly of claim 12 wherein the material of said ceramic shaft portion is selected from a group consisting of silicon nitride and silicon carbide.

16. A joint assembly, comprising:

17. A joint assembly, comprising:

18. A joint assembly, comprising:

d

1

/d

2=(

c

1)/(

2

1),

where

c is the coefficient of thermal expansion of said ceramic shaft portion,

1 is the coefficient of thermal expansion of said first material, and

2 is the coefficient of thermal expansion of said second material.

19. A joint assembly, comprising:

20. The assembly of claim 19 wherein said soft metal layer is selected from the group consisting of nickel, cobalt, platinum, platinum and rhodium, nickel oxide, cobalt oxide and combinations thereof.

21. The assembly of claim 20 wherein said soft metal layer comprises at least one layer selected from a group consisting of nickel, cobalt, platinum, platinum and rhodium, and an oxide layer over said one layer.