COPPER-COATED TITANIUM DIBORIDE ARTICLES

Abstract

New copper-coated titanium diboride electrodes are disclosed. The copper-coated titanium diboride electrodes may be used in an aluminum electrolysis cell. In one embodiment, a method includes installing the copper-coated titanium diboride electrode in the aluminum electrolysis cell and operating the aluminum electrolysis cell. During start-up, the aluminum electrolysis cell may be preheated and a bath may be formed from a molten electrolyte. Alumina (Al.sub.2O.sub.3) may in the added to the bath and reduced to aluminum metal. At least some of the copper film of the copper-coated titanium diboride electrode may be replaced by an aluminum film, thereby forming an aluminum-wetted titanium diboride electrode.

Claims

1. A method comprising: (a) making a titanium diboride electrode; (b) forming a copper film on the titanium diboride electrode, thereby forming a copper-coated titanium diboride electrode.

2. The method of claim 1, wherein the forming step (b) comprises electroless deposition or electroplating.

3. The method of claim 1, wherein, after the copper film comprises a nominal thickness of from 10 to 200 micrometers.

4. The method of claim 1, wherein the copper film is continuous and at least partially covers the outer surface of the titanium diboride electrode.

5. The method of claim 1, wherein the copper film comprises a uniform thickness, wherein a maximum and minimum thickness of the copper film are within 50% of an average thickness of the copper film.

6. The method of claim 1, comprising: preparing the titanium diboride electrode for the forming step (b), wherein the preparing comprises at least one of: (i) cleaning of the titanium diboride electrode; and (ii) rinsing of the titanium diboride electrode.

7. The method of claim 6, wherein the cleaning step comprises contacting the titanium diboride electrode with one or more acids and at temperature of from room temperature to 95° C.

8. The method of claim 7, wherein the rinsing comprises contacting the titanium diboride electrode with water.

9. The method of claim 1, comprising: using the copper-coated titanium diboride electrode in an aluminum electrolysis cell.

10. The method of claim 9, wherein the using comprises using the copper-coated titanium diboride electrode as an anode.

11. The method of claim 9, wherein the using comprises using the copper-coated titanium diboride electrode as a cathode.

12. The method of claim 9, wherein the using comprises using the copper-coated titanium diboride electrode as a sidewall.

13. The method of claim 9, wherein the using comprises: prior to operating the aluminum electrolysis cell, installing the copper-coated titanium diboride electrode in the aluminum electrolysis cell; and starting-up the aluminum electrolysis cell, wherein the starting-up comprises: preheating the aluminum electrolysis cell; adding a molten electrolyte to the aluminum electrolysis cell, thereby forming a bath applying DC current, via the copper-coated titanium diboride electrode, to the bath; dissolving alumina (Al.sub.2O.sub.3) in the bath; reducing the dissolved alumina to aluminum metal; and replacing at least some of the copper film of the copper-coated titanium diboride electrode with an aluminum film, thereby forming an aluminum-wetted titanium diboride electrode, wherein the replacing comprises: dissolving at least a portion of the copper film via the aluminum metal of the bath.

14. The method of claim 13, comprising: after the starting-up step, making commercially purity aluminum in the aluminum electrolysis cell via the aluminum-wetted titanium diboride electrode.

15. The method of claim 14, wherein the using comprises using the copper-coated titanium diboride electrode in a vertical orientation.

16. The method of claim 15, wherein the making step comprises: producing aluminum metal at or near outer surfaces of the vertically oriented, aluminum-wetted titanium diboride electrode; and flowing the aluminum metal down the vertically oriented, aluminum-wetted titanium diboride electrode.

17. The method of claim 13, wherein the preheating the aluminum electrolysis cell comprises heating to a temperature of at least 600° C.

18. The method of claim 13, comprising: dissolving, via the bath, copper oxides on surfaces of the copper-coated titanium diboride electrode.

19. The method of claim 13, wherein, during the reducing the dissolved alumina to aluminum metal step, the copper-coated titanium diboride electrode is at least partially submerged in the bath.

20. The method of claim 13, wherein the dissolving step comprises dissolving a first portion of the copper film of the copper-coated titanium diboride electrode, wherein the method comprises: maintaining a second portion of the copper film of the copper-coated titanium diboride electrode during the operating the aluminum electrolysis cell step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1 is a flow chart showing one embodiment of a method for making aluminum in accordance with the present disclosure.

[0043] FIG. 2 is a flow chart illustrating one embodiment of the making step (100) of FIG. 1.

[0044] FIG. 3 is a flow chart illustrating one embodiment of the forming step (200) of FIG. 1.

[0045] FIG. 4 is a flow chart illustrating one embodiment of the using step (300) of FIG. 1.

[0046] FIG. 5a illustrates one embodiment of a schematic view of a TiB.sub.2 electrode assembly useful with an aluminum electrolysis cell comprises a vertical electrode arrangement.

[0047] FIG. 5b is a side view of the electrode assembly of FIG. 5a.

[0048] FIG. 5c is a close-up view of an electrode of FIG. 5a disposed in an electrolytic bath.

[0049] FIG. 6 is an SEM photograph illustrating a copper film on a titanium diboride electrode.

[0050] FIGS. 7a-7b are graphs illustrating EDS measurements of the SEM of FIG. 6.

[0051] FIGS. 8a-8c are SEMs illustrating electrodes having nominal copper film thicknesses of 26, 70-80, and 144 micrometers, respectively.

DETAILED DESCRIPTION

Example 1

[0052] Several titanium diboride electrodes were made in accordance with the description of Section II, above, and commonly-owned U.S. Pat. No. 8,211,278. These titanium diboride electrodes were then cleaned via an acid and rinsed in deionized water, after which the electrode was subjected to electroplating to form a copper film thereon. These titanium diboride electrodes were then used in a pilot-size aluminum electrolysis cell for approximately five days, during which aluminum metal was electrolytically produced. After cell operations concluded, the electrodes were removed from the cells and examined. No visible degradation was seen. An SEM photograph and EDS measurements of one titanium diboride electrode were taken relative to an unsubmerged portion of the electrode (i.e., the part of the electrode that was not submerged in the bath), the results of which are shown in FIGS. 6 and 7a-7b. As shown in FIG. 6, the copper film (640) is uniform and uninterrupted. Further, the titanium diboride electrode (620) is intact and shows no signs of penetration. As shown in FIGS. 7a-7b, the EDS of the titanium diboride portion (620) shows no signs of contamination and the copper film (640) generally consists of metallic copper.

[0053] While a number of embodiments of the present invention have been described, it is understood that these embodiments are illustrative only, and not restrictive, and that many modifications may become apparent to those of ordinary skill in the art. Further still, unless the context clearly requires otherwise, the various steps may be carried out in any desired order, and any applicable steps may be added and/or eliminated.