Sinter-bonded direct pin connections for inert anodes

• US 6,855,234 B2
• Filed: 04/02/2003
• Issued: 02/15/2005
• Est. Priority Date: 04/02/2003
• Status: Expired due to Fees

• Current Assignee: Alcoa USA Corp. (Alcoa Corp.)
• Original Assignee: Alcoa Incorporated (Howmet Aerospace, Inc.)
• Inventors: D'Astolfo, Leroy E. Jr.
• Primary Examiner(s): Bell, Bruce F.
• Application Number:
  US10/405,761
• Publication Number:
  US 20040195092A1
• Time in Patent Office: 685 Days
• Field of Search: 297/45, 297/46, 204/243.1, 204/247.3, 204/280, 204/291, 204/292, 204/293, 205/380, 205/384, 205/386, 205/388
• US Class Current: 204/280
• CPC Class Codes: C25C 3/12 Anodes
• CPC Class Codes: C25C 7/025 used in cells for the electrolysis of melts
• CPC Class Codes: Y10T 29/532 Conductor
• CPC Class Codes: Y10T 29/53204 Electrode

Abstract

A sintered electrode assembly is made of an inert electrode (15) containing a sealed metal conductor (20) having a surface feature (30) such as a coating or wrapping which aids in bond formation with the inert electrode (15) at their interface (45), where the metal conductor (20) is directly contacted by and is substantially surrounded by the inert electrode (15) without the use of metal foam or metal powders.

Claims

1. A sintered electrode assembly comprising:

an inert electrode containing a sealed metal conductor rod, the conductor rod having a surface feature to aid in direct bond formation with the inert electrode, where the conductor rod is directly contacted by and is surrounded by the inert electrode to provide a tight fit between the conductor rod and inert electrode.

2. The electrode assembly of claim 1, wherein the inert anode is selected from the group consisting of ceramic, cermet and metal containing inert anodes, and the tight fit between the conductor rod and inert electrode after sintering is one of an interference fit or direct compression fit, providing continuous coherent contact at their interface.

3. The electrode assembly of claim 1, wherein the metal conductor is selected from the group consisting of nickel, nickel alloy, Inconel, copper, copper alloy, and a corrosion protected steel.

4. The electrode assembly of claim 1, wherein the metal conductor has a circular cross-section and the coefficient of expansion of the conductor is about 2% to 50% higher than the coefficient of expansion of the inert anode.

5. The electrode assembly of claim 1, wherein the surface feature is a chemical/mechanical material comprising an alloy selected from the group consisting of nickel, nickel-copper alloy, copper, copper alloy, tin alloy, silver and silver alloy which has been pre-applied to the metal conductor as a coating or wrapping and melts between about 1050°

C. and about 1450°

C.

6. The electrode of claim 1, wherein the surface feature is a chemical/mechanical material consisting essentially of a flux material layer, pre-applied or rising to the contact surface of the conductor during sintering.

7. The electrode of claim 1, wherein the surface feature is a non-smooth surface.

8. A sintered electrode assembly comprising:

an inert electrode having a hollow interior with a top portion and interior bottom and side walls;

a metal pin conductor rod having bottom and side surfaces, disposed within the hollow electrode interior and directly contacting the inert electrode interior walls with the aid of a surface feature on the conductor rod to aid in bond formation with the inert electrode, to provide a tight fit between the conductor rod and inert electrode.

9. The electrode assembly of claim 8, wherein the inert anode is selected from the group consisting of ceramic, cermet and metal containing inert anodes, and the tight fit between the conductor rod and inert electrode after sintering is one of an interference fit or direct compression fit, providing continuous coherent contact at their interface.

10. The electrode assembly of claim 8, wherein the metal conductor is selected from the group consisting of nickel, nickel alloy, Inconel, copper, copper alloy and a corrosion protected steel.

11. The electrode assembly of claim 8, wherein the metal conductor has a circular cross-section.

12. The electrode assembly of claim 8, wherein the surface feature is a chemical/mechanical material comprising an alloy selected from the group consisting of nickel, nickel-copper alloy, copper, copper alloy, tin alloy, silver and silver alloy which has been pre-applied to the metal conductor as a coating or wrapping and melts between about 1050°

C. and about 1450°

C.

13. The electrode of claim 8, wherein the surface feature is a chemical/mechanical material consisting essentially of a flux material layer, pre-applied or rising to the contact surface of the conductor during sintering.

14. The electrode of claim 8, wherein the surface feature is a non-smooth surface.

15. The sintered electrode assembly of claim 8, wherein a mechanical-electrical bond is formed as the interface of the conductor and inert electrode as the inert electrode material shrinks around the conductor.

16. The sintered electrode assembly of claim 8, wherein the coefficient of expansion of the conductor is from about 2% to 50% times higher than the coefficient of expansion of the inert electrode.

17. A method of producing an electrode assembly comprising the steps:

(1) providing an inert anode electrode having a hollow interior with a top portion and interior bottom and side walls;

(2) providing a metal pin conductor rod having a surface feature on the surface of or within the conductor;

(3) inserting said conductor rod into said inert electrode, and

(4) sintering to achieve a chemical/mechanical connection, where, during the sintering the surface feature aids bonding, and where sintering provides a tight fit between the conductor rod and inert electrode, providing continuous coherent contact at the conductor rod-inert electrode interface.

18. The method of claim 17, wherein the surface feature is selected from the group consisting of nickel, nickel-copper alloy, copper, copper alloy, tin alloy, silver and silver alloy, which has been pre-applied to the metal conductor as a coating or wrapping.

19. The method of claim 17, wherein the surface feature is a flux material layer, pre-applied or migrating to the contact surface of the conductor during sintering.

20. The method of claim 17, wherein the surface feature is a non-smooth surface.

21. The method of claim 17, wherein, in step (3) there is a gap between the conductor and electrode, which is closed in step (4).

22. The method of claim 17, wherein, in step (3) there is a tight compression fit between the conductor and electrode, which remains after step (4).

23. The method of claim 17, wherein the conductor contains on its body or on its surface a flux material and has a melting temperature lower than the sintering temperature and melts during step (4) such that the flux material promotes metal flow and fusing of the metal to the inert anode material.