Wettable and erosion/oxidation-resistant carbon-composite materials

• US 6,649,040 B1
• Filed: 09/28/2001
• Issued: 11/18/2003
• Est. Priority Date: 11/17/1998
• Status: Expired due to Fees

• Current Assignee: Alcan Incorporated (Rio Tinto Limited)
• Original Assignee: Alcan Incorporated (Rio Tinto Limited)
• Inventors: Mirchi, Amir A., Bergeron, Jules
• Primary Examiner(s): Valentine, Donald R.
• Application Number:
  US09/831,375
• Time in Patent Office: 781 Days
• Field of Search: 205/390, 205/386, 423/439, 423/440, 423/297
• US Class Current: 205/390
• CPC Class Codes: C04B 2235/3232 Titanium oxides or titanates, e.g. rutile or anatase
• CPC Class Codes: C04B 2235/3239 Vanadium oxides, vanadates or oxide forming salts thereof, e.g. magnesium vanadate
• CPC Class Codes: C04B 2235/3241 Chromium oxides, chromates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3244 Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3251 Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3256 Molybdenum oxides, molybdates or oxide forming salts thereof, e.g. cadmium molybdate
• CPC Class Codes: C04B 2235/3409 Boron oxide, borates, boric acids, or oxide forming salts thereof, e.g. borax
• CPC Class Codes: C04B 2235/3813 Refractory metal borides
• CPC Class Codes: C04B 2235/3843 Titanium carbides
• CPC Class Codes: C04B 2235/48 Organic compounds becoming part of a ceramic after heat treatment, e.g. carbonising phenol resins
• CPC Class Codes: C04B 2235/604 Pressing at temperatures other than sintering temperatures
• CPC Class Codes: C04B 2235/80 Phases present in the sintered or melt-cast ceramic products other than the main phase
• CPC Class Codes: C04B 2235/9676 against molten metals such as steel or aluminium
• CPC Class Codes: C04B 35/52 based on carbon, e.g. graphite
• CPC Class Codes: C04B 35/532 containing a carbonisable binder
• CPC Class Codes: C04B 35/58071 based on titanium borides
• CPC Class Codes: C04B 35/63496 Bituminous materials, e.g. tar, pitch
• CPC Class Codes: C25C 3/08 Cell construction, e.g. bottoms, walls, cathodes

Abstract

A thermal treatment system for thermally treating a sterile medium is controlled via a foot actuated switch to thermally treat the sterile medium to a desired temperature and/or form (e.g., slush). The thermal treatment system includes a basin recessed in a system top surface, while a surgical sterile drape is placed over the system and within the basin to form a drape container for containing the sterile medium. The basin may be configured to cool the sterile medium and form sterile surgical slush, or heat the sterile medium to provide warm sterile liquid. A dislodgment mechanism may be employed within a cooling basin to manipulate the drape and dislodge frozen pieces of sterile medium adhered to the drape. Information pertaining to the sterile medium and system operation may be displayed on a system display that has dimensions sufficient to provide visibility of the information to users located within extended ranges from the system. Alternatively, the thermal treatment system may be responsive to a remote control unit to enable users to control operation of the system remotely. The remote control unit may control various operating parameters and features of the system, and preferably emits system commands in the form of code signals. A receiver is employed by the thermal treatment system to receive the transmitted signals and facilitate system operation in response to those signals. In addition, the foot actuated switch and remote control unit may be utilized with thermal treatment systems having a plurality of heating and/or cooling basins.

Claims

1. A process of producing a carbon composite material comprising carbon and a metal boride as all or part of a cathode or cell lining, including side wall block, of an aluminum electrolysis cell which process comprises,

mixing together quantities of precursors of a metal boride to produce a precursor mixture, wherein the precursors are in the form of solid powders having an average particle size of less than 100 microns;

mixing said precursor mixture with at least one carbon-containing component to form a carbon-containing precursor mixture;

without pre-reacting said precursors to form said metal boride, positioning said carbon-containing precursor mixture in an aluminum electrolysis cell to form all or part of a cathode or lining of said cell; and

proceeding with cell start-up and operation, thereby exposing said carbon-containing precursor mixture to a reducing environment in said cell such that said precursors react together to generate said carbon composite material comprising carbon and said metal boride in situ in said cell.

2. A process according to claim 1, wherein a minor amount of the metal boride is added to said carbon-containing precursor mixture.

3. A process according to claim 2, wherein said minor amount is in the range of 3 to 10% by weight of said carbon-containing precursor mixture.

4. A process according to claim 1, wherein one of said precursors used to form said precursor mixture is selected from the group consisting of boron oxide, boric acid and borax, and another is an oxide of a metal selected from the group consisting of titanium, zirconium, vanadium, hafnium, niobium, tanalum, chromium and molybdenum.

5. A process according to claim 1, wherein one of said precursors used to form said precursor mixture is selected from the group consisting of B₂O₃ and boric acid, and another is TiO₂.

6. A process according to claim 1, wherein one of said precursors used to form said precursor mixture is selected from the group consisting of B₂O₃ and boric acid, and another is selected from the group consisting of V₂O₅ and V₂O₃.

7. A process according to claim 1, wherein said precursor mixture is mixed with said at least one carbon-containing component in an amount that generates said metal boride in a quantity forming at least 5% by weight of said carbon composite material after exposure to said cell start-up and operation.

8. A process according to claim 1, wherein said precursor mixture is mixed with said at least one carbon-containing component in an amount that generates a quantity of said metal boride, after exposure to said cell start-up and operation conditions, making surfaces of said material wettable by molten aluminum.

9. A process according to claim 8, wherein said quantity is at least about 30% by weight of said carbon composite material.

10. A process according to claim 1, wherein said at least one carbon-containing component is a mixture of anthracite and pitch.

11. A process according to claim 1, in which the carbon-containing precursor mixture is compressed to form a block, and the block is pre-baked before cell start-up.

12. A process according to claim 11, wherein the block is pre-baked at a temperature in the range of 1000-1300°

C.

13. A carbon composite material forming all or part of a cathode or cell lining of an aluminum electrolysis cell, said material having been produced by a process according to claim 1.

14. A carbon composite material suitable for use in preparing all or part of a cathode or cell lining, including a side wall block, of an aluminum electrolysis cell,

said material is produced by mixing together quantities of precursors of a metal boride to produce a precursor mixture, wherein the precursors are in the form of solid powders having an average particle size of less than 100 microns;

and mixing said precursor mixture with at least one carbon-containing component to form a carbon-containing precursor mixture.

15. A material according to claim 14, further containing a minor amount of said metal boride.

16. A material according to claim 15, wherein said minor amount is in the range of 3 to 10% by weight of said carbon composite material.

17. A material according to claim 14, wherein one of said precursors is selected from the group consisting of boron oxide, boric acid and borax, and another is an oxide of a metal selected from the group consisting of titanium, zirconium, vanadium, hafnium, niobium, tanalum, chromium and molybdenum.

18. A material according to claim 14, wherein one of said precursors is selected from the group consisting of B₂O₃ and boric acid, and another is TiO₂.

19. A material according to claim 14, wherein one of said precursors is selected from the group consisting of B₂O₃ and boric acid, and another is selected from the group consisting of V₂O₅ and V₂O₃.

20. A material according to claim 14, wherein said precursors are present in an amount that generates said metal boride in a quantity forming at least 5% by weight of said material after exposure to electrolysis cell start-up and operation.

21. A material according to claim 14, wherein said precursors are present in an amount that generates a quantity of said metal boride making surfaces of said material, after exposure to electrolysis cell start-up and operation, wettable by molten aluminum.

22. A material according to claim 21, wherein said quantity is at least about 30% by weight of said material.

23. A material according to claim 14, wherein said at least one carbon-containing component is a mixture of anthracite and pitch.

24. A material according to claim 14, in the form of a pre-baked cell lining block.

25. A carbon composite material suitable for immersion in molten aluminum, said material comprising quantities of precursors of a metal boride and at least one carbon-containing component to form said carbon composite material;

wherein said precursors of said metal boride are in the form of pre-mixed solid powders having a particle size of less than 100 microns; and

wherein said precursors react together to generate said metal boride in situ when said material is exposed to molten aluminum.

26. A process of producing a carbon composite material comprising carbon and a metal boride as all or part of a cathode or cell lining, including side wall block, of an aluminum electrolysis cell which process comprises, intimately mixing together quantities of precursors of a metal boride to produce a precursor mixture, wherein one of said precursors is selected from the group consisting of boron oxide, boric acid and borax, and another of said precursors is an oxide of a metal selected from the group consisting of titanium, zirconium, vanadium, hafnium, niobium, tantalum, chromium and molybdenum, and wherein the precursors are in the form of solid powders having an average particle size of less than 100 microns;

mixing said precursor mixture with at least one carbon-containing component selected from the group consisting of anthracite, pitch, tar and graphite to form a carbon-containing precursor mixture;

without pre-reacting said precursors to form said metal boride, positioning said carbon-containing precursor mixture in an aluminum electrolysis cell to form all or part of a cathode or lining of said cell; and

proceeding with cell start-up and operation at a temperature in the range of 600 to 1100°

C., thereby exposing said carbon-containing precursor mixture to a reducing environment in said cell such that said precursors react together to generate said carbon composite material comprising carbon and said metal boride in situ in said cell.