Pressure and mechanical sensors using titanium-based superelastic alloy

• US 7,437,939 B1
• Filed: 04/13/2007
• Issued: 10/21/2008
• Est. Priority Date: 04/13/2007
• Status: Expired due to Fees

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Broden, David A., Chakraborty, Swapan
• Primary Examiner(s): Allen; Andre J
• Application Number:
  US11/787,048
• Publication Number:
  US 20080253058A1
• Time in Patent Office: 557 Days
• Field of Search: 737/15, 737/18, 737/24, 210/490
• US Class Current: 73/715
• CPC Class Codes: G01L 9/0072 using variations in capacitance

Abstract

Pressure and mechanical sensors include a sensing component formed of a titanium and tantalum alloy having an elastic (Young'"'"'s) modulus of less than about 80 GPa and a tensile strength of greater than about 1,000 MPa. The high strength and low elastic modulus, together with very low temperature dependence of the elastic modulus and very low linear thermal expansion, result in high resolution and precise measurement over a large temperature range.

Claims

1. A sensor characterized by a deflectable component responsive to a parameter to be sensed and formed of a titanium-based alloy having a Young'"'"'s modulus of less than about 80 GPa and a tensile strength of greater than about 1,000 MPa.

2. The sensor of claim 1 and further comprising a sensor body, wherein the deflectable component is mounted to the sensor body.

3. The sensor of claim 2, wherein the parameter to be sensed is pressure, and wherein the sensor body and the deflectable component define at least one pressure sensing chamber.

4. The sensor of claim 3, wherein the sensor comprises a capacitive differential pressure sensor and wherein the deflectable component comprises a central diaphragm positioned between a first chamber and a second chamber, the central diaphragm being deflectable as a function of fluid pressure in the first and second chambers.

5. The sensor of claim 4, wherein the first and second chambers are filled with dielectric fill fluid, and wherein first and second isolation diaphragms transmit pressure from a process fluid to the dielectric fill fluid in the first and second chambers, respectively.

6. The sensor of claim 5, wherein the first and second isolation diaphragms are formed of the titanium-based alloy.

7. The sensor of claim 1 and further comprising a strain responsive device attached to the deflectable component for producing an output as a function of deflection of the deflectable component.

8. The sensor of claim 1 and further comprising a circuit for providing an output as a function of resistance of the deflectable component that changes based upon deflection of the deflectable component.

9. The sensor of claim 1, wherein the titanium-based alloy includes titanium, at least one group IVa element, at least one group Va element other than titanium, and at least one interstitial element.

10. The sensor of claim 9, wherein the at least one group IVa element is from a group consisting of zirconium and hafnium, wherein the group Va element is from a group consisting of niobium, tantalum and vanadium, and wherein the interstitial element is from a group consisting of oxygen, nitrogen and carbon.

11. The sensor of claim 10, wherein the titanium-based alloy comprises a composition of Ti—

24 at % (Nb+Ta+V)—

(Zr, Hf)—

O.

12. The sensor of claim 1, wherein the titanium-based alloy has a compositional average balance electron number [electron/atom (ea) ratio] of about 2.24;

has a bond order (Bo value) of about 2.86 to about 2.90 based on a DV-Xα

cluster method; and

has a “

D”

electron-orbital energy level (Md value) of about 2.43 to about 2.49.

13. A pressure sensor comprising:

a first chamber; and

a diaphragm positioned adjacent the first chamber, the diaphragm formed of a titanium-based alloy having a Young'"'"'s modulus of less than about 80 GPa and a tensile strength of greater than about 1,000 MPa.

14. The pressure sensor of claim 13 and further comprising:

a capacitance that varies as a function of deflection of the diaphragm.

15. The pressure sensor of claim 13 and further comprising:

a strain responsive device attached to the diaphragm for producing an output as a function of deflection of the diaphragm.

16. The pressure sensor of claim 13 and further comprising;

electrical contacts connected to the diaphragm to provide a resistance as a function of deflection of the diaphragm.

17. The capacitive pressure sensor of claim 13, wherein the titanium-based alloy has a Young'"'"'s modulus of less than about 70 GPa.

18. The capacitive pressure sensor of claim 17, wherein the titanium-based alloy has a Young'"'"'s modulus of about 60 GPa.

19. The capacitive pressure sensor of claim 13, wherein the titanium-based alloy has a tensile strength of greater than about 1200 MPa.

20. The capacitive pressure sensor of claim 13, wherein the titanium-based alloy includes group IVa and group Va elements.

21. The capacitive pressure sensor of claim 20, wherein the titanium-based alloy comprises a composition of Ti-24 at % (Nb+Ta+V)—

(Zr, Hf)—

O.

22. The capacitive pressure sensor of claim 13, wherein the titanium-based alloy has a compositional average balance electron number [electron/atom (ea) ratio] of about 2.24;

has a bond order (Bo value) of about 2.86 to about 2.90 based on a DV-Xα

cluster method; and

has a “

D”

electron-orbital energy level (Md value) of about 2.43 to about 2.49.

23. A pressure sensor comprising:

a sensor body;

a diaphragm supported by the sensor body and deflectable as a function of the fluid pressure, the diaphragm having a Young'"'"'s modulus of less than about 80 GPa and a tensile strength of greater than about 1000 MPa; and

means for producing an output representative of sensed pressure based upon deflection of the diaphragm.

24. The pressure sensor of claim 23, wherein the means for producing an output is responsive to a capacitance that changes as a function of deflection of the diaphragm.

25. The pressure sensor of claim 23, wherein the means for producing an output is responsive to a resistance that changes as a function of deflection of the diaphragm.

26. The pressure sensor of claim 23, wherein the means for producing an output is responsive to strain that changes as a function of deflection of the diaphragm.

27. The pressure sensor of claim 23, wherein the diaphragm has a Young'"'"'s modulus of less than about 70 GPa.

28. The pressure sensor of claim 27, wherein the diaphragm has a Young'"'"'s modulus of about 60 GPa.

29. The pressure sensor of claim 23, wherein the diaphragm has a tensile strength of greater than about 1200 MPa.

30. The pressure sensor of claim 23, wherein the diaphragm is formed of a titanium-based alloy.

31. The pressure sensor of claim 30, wherein the titanium-based alloy includes group IVa and group Va elements.

32. The pressure sensor of claim 31, wherein the titanium-based alloy comprises a composition of Ti-24 at % (Nb+Ta+V)—

(Zr, Hf)—

O.

33. The pressure sensor of claim 30, wherein the titanium-based alloy has a compositional average balance electron number [electron/atom (ea) ratio] of about 2.24;

has a bond order (Bo value) of about 2.86 to about 2.90 based on a DV-Xα

cluster method; and

has a “

D”

electron-orbital energy level (Md value) of about 2.43 to about 2.49.