EP0094353B1 - Matériaux mouillables par l'aluminium - Google Patents

Matériaux mouillables par l'aluminium Download PDF

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Publication number
EP0094353B1
EP0094353B1 EP83810197A EP83810197A EP0094353B1 EP 0094353 B1 EP0094353 B1 EP 0094353B1 EP 83810197 A EP83810197 A EP 83810197A EP 83810197 A EP83810197 A EP 83810197A EP 0094353 B1 EP0094353 B1 EP 0094353B1
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EP
European Patent Office
Prior art keywords
aluminum
cell
molten
coating
wettable
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EP83810197A
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German (de)
English (en)
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EP0094353A2 (fr
EP0094353A3 (en
Inventor
Ajit Y. Sane
Douglas J. Wheeler
Charles S. Kuivila
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Eltech Systems Corp
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Eltech Systems Corp
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Priority to AT83810197T priority Critical patent/ATE32107T1/de
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Publication of EP0094353A3 publication Critical patent/EP0094353A3/en
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/16—Electric current supply devices, e.g. bus bars
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/08—Cell construction, e.g. bottoms, walls, cathodes

Definitions

  • the present invention relates to a molten salt aluminum production cell comprising an aluminum wettable component exposed to molten aluminum in said cell, the component being essentially made of an aluminum non-wettable material rendered aluminum wettable by coating it with a compound containing the elements of a wetting agent and a solubility suppressor for said wetting agent.
  • Aluminum is commonly produced by electrowinning aluminum from AI 2 0 3 (alumina) at about 900°C to 1,000°C. Aluminum oxide being electrowon frequently is dissolved in molten Na 3 AIF 6 (cryolite) that generally contains other additives helpful to the electrowinning process such as CaF z , AIF 3 and possibly LiF or MgF 2 .
  • anode and cathode are arranged in vertical spaced configuration within the cell, the anode being uppermost. Reduction of aluminum oxide to aluminum occurs at the cathode which customarily is positioned at the bottom or floor of the cell. Oxygen is disassociated from A1 2 0 3 , in most commercial cells combining with carbonaceous material comprising the cell anode and being emitted from the cell as CO and CO 2 ,
  • Cryolite is an aggressive chemical necessitating use of a cathode material substantially resistant to this aggressive cryolite.
  • a cathode material substantially resistant to this aggressive cryolite.
  • One popular choice is the use of molten aluminum as a cathode. While use of other cathodes such as bare graphite in contact with cryolite has been contemplated, formation of undesirable by-products such as aluminum carbide has discouraged use. In many commercial cells, this cathode often covers substantially the entire floor of the cell which typically can be 6 feet wide by 18 or more feet in length.
  • the cathode In utilizing aluminum for cathode purposes in a cell, typically the cathode is included in an assembly of a cathodic current feeder covered by a pool of aluminum ranging in depth, depending upon the cell, from a few inches to in excess of a foot, but generally about 6 inches.
  • the aluminum pool functions effectively as a cathode and also serves to protect current feeders made from materials less than fully resistant to cell contents.
  • These aluminum pool type cell cathode assemblies contain conductive current collectors. Where these conductive current collectors are utilized in certain cell configurations, these collectors contribute to an electrical current flow within the cell that is not perpendicular to the cell bottom. These nonperpendicular electrical currents can interact with strong magnetic fields established around cells by current flow through busses and the like to contribute to strong electromagnetic fluxes within the cell.
  • cryolite In cells employing a pool of aluminum covering the cathode floor of the cell, the cryolite, containing A1 2 0 3 to be electrolyzed, floats atop this aluminum pool.
  • the cell anodes are imfnersed in this cryolite layer.
  • cell anodes are generally positioned within the cryolite substantially above the normal or expected level of the interface between molten cryolite and molten aluminum within the cell. Usually, a spacing of 3.75-6.25 cm (1'2 to 2; inches) is utilized.
  • drained cathodes In such cells, no pool of aluminum is maintained upon a cathode current feeder to function as a cathode; electrowon aluminum drains from the cathode at the bottom of the cell to be recovered from a collection area.
  • drained cathode cells without wave action attendant to a molten aluminum pool, the anode and the cathode may be quite closely arranged, realizing significant electrical power savings.
  • the cathode In these drained cathode cells, the cathode, particularly where non-wettable by molten aluminum, is in generally continuous contact with molten cryolite.
  • This aggressive material in contact with a graphite or carbon cathode, can contribute to material loss from the cathode and can trigger formation of such undesirables as aluminum carbide.
  • Particularly carbon or graphite for use as a drained cathode material of construction is therefore of quite limited utility due to possible service life constraints and carbide contaminant formation.
  • the molten cryolite can contribute to TiB 2 corrosion by fluxing reaction products of a reaction between impure TiB 2 and aluminum, particularly near grain boundaries of the material. While it is known that in aluminum electrowinning cells utilizing essentially pure TiB 2 do not exhibit as substantial a corrosion susceptibility as do those employing lower purity TiB 2 , cost and availability factors seriously limit the use of TiB 2 sufficiently pure to withstand an aggressive aluminum cell environment.
  • cryolite Conventionally, most cells employ construction materials that are either wettable by molten aluminum, are relatively inert to the corrosive effects of cryolite or both. Where a substance is not readily wetted by molten aluminum, even though immersed in molten aluminum the substance may contact cryolite present at the interface between the substance and the molten aluminum due to poor wetting. Where the substance is significantly soluble in cryolite, or corroded by cryolite, substantial material losses to the substrate therefore can occur.
  • substrates substantially wettable by molten aluminum tend, while immersed in the molten aluminum, to be protected from the deleterious effects of contact with molten cryolite.
  • a sheathing effect by the molten aluminum protects the substance.
  • Aluminum wettable substances such as refractory TiB 2 have therefore been suggested for constructing components of cells which are to be immersed in molten aluminum.
  • aluminum nonwettable materials particularly those such as alumina which are subject to attack/ dissolution by molten cryolite, for fabrication of cell components. This reluctance may be enhanced where dimensional stability of the component is relatively important, for example in the fabrication of electrical current feeders, weirs, sidewalls, and the like.
  • an aluminum production cathode comprising a top layer of porous structure which is coated with e.g. TiB 2 .
  • the porous top layer is infiltrated with molten aluminum saturated with Ti.
  • TiB 2 e.g. TiB 2
  • EP-A-0 069 502 also unpublished before the filing date of the present application discloses cell components of TiB 2 or comprising a coating of TiB 2 . It is known in the art that TiB 2 coatings on components which are immersed in molten aluminum render the substrate aluminum wettable. However, it is also known that TiB 2 has a certain solubility in molten aluminum and does therefore not quality for long term operation under known conditions.
  • EP-A-0 021 850 discloses an aluminum cathode of carbon which comprises a coating of TiB 2 . This coating is produced by electrodeposition from an electrolyte containing titanium and boron. Long term operation of this coated cathode once produced and installed in an operating cell is impaired by the same reasons as mentioned in the preceding paragraph.
  • the present invention provides a molten salt aluminum production cell as set out under the heading "Technical Field of the Invention", wherein the molten aluminum contains said wetting agent and said solubility suppressor in concentrations near saturation.
  • the present invention further provides a method of maintaining aluminum wettability of a component of the above aluminum production cell.
  • the present invention provides a method for making substrates used in, or components of an aluminum electrowinning cell substantially wettable and thereby at least partially filled where porous by molten aluminum where those components or substrates normally would not be aluminum wetted in the environment of the cell. Used in the electrowinning cell, these wettable components, when immersed in molten aluminum contained in the cell are stable in the cell environment even where the materials from which the substrates were fabricated would otherwise be subject to aggressive attack by materials such as cryolite contained in the cell.
  • Substrates are made wettable by molten aluminum by applying to the substrate a coating of a compound containing the elements of a wetting agent and a solubility suppressor for the wetting agent prior to or while the substrate is immersed in molten aluminum, and the molten aluminum is maintained near saturation with the wetting agent and solubility suppressor by introducing the wetting agent and the solubility suppressor into the molten aluminum to maintain desired levels in the molten aluminum.
  • the coating applied to the substrate is preferably quite thin.
  • the coating need not be continuous.
  • the method preferably is utilized to make refractory materials commonly non aluminum wettable, amenable to wetting by aluminum. Once aluminum wettable, these refractory materials can be utilized for a variety of purposes within an aluminum electrowinning cell including weirs, current feeders, packing, baffles, structural components and the like.
  • Fig. 1 is a cross sectional representation of an aluminum electrowinning cell.
  • Fig. 1 shows in cross section a representation of an aluminum electrowinning cell 10.
  • the cell includes a base 14 and sidewalls 16, 18, generally of steel, surrounding the cell.
  • the cell includes a cathodic current feeder 20 and anodes 22, 24.
  • the base and sidewalls enclose the cathodic current feeder 20 which in this best embodiment functions also as a cell liner. Portions 26 of the liner define a floor of the cell. Well known refractory materials and graphite are suitable for fabricating this current feeder 20, as are other suitable or conventional materials.
  • a current buss 28, embedded in the feeder 20 provides electrical current for distribution within the cell 10. The buss 28 is connected to an external source of electrical current (not shown).
  • the anodes 22, 24 are arranged in vertical spaced relationship with the current feeder portions 26 defining the floor of the cell.
  • the anodes 22, 24 are separated from the cathodic current feeder by two pools 30, 32 of molten material.
  • One pool 30 comprises essentially molten aluminum. This molten aluminum pool functions as a cathode for electrowinning of aluminum within the cell. While the pool consists essentially of molten aluminum, impurities customarily associated with aluminum produced electrolytically may be present.
  • the remaining pool 32 is comprised of molten cryolite, Na 3 AIF 6 , containing dissolved A1 2 0 3 .
  • a number of cryolite formulations that include additives such as CaF 2 , LiF, and AIF 3 for enhancing electrolysis of the A1 2 0 3 to aluminum are possible and are contemplated as being utilized within the scope of the invention.
  • This cryolite layer being less dense than the molten aluminum, floats upon the aluminum.
  • An interface 36 separates the molten aluminum 30 from the molten cryolite 32.
  • An insulating layer 39 is provided to resist heat flow from the cell 10. While a variety ofwell-known structures are available for making this insulating structure, often the insulating layer 39 is crystallized contents of the electrolytic cell.
  • the anodes 22, 24 are fabricated from any suitable or conventional material and immersed in a cryolite phase 32 contained in the cell. Since oxygen is released in some form at the anode, the anode material must be either resistant to attack by oxygen or should be made of a material that can be agreeably reacted with the evolving oxygen, preferably producing a lower anode half cell voltage by virtue of reactive depolarization. Typically, carbon or graphite is utilized providing a depolarized anode.
  • the anodes 22, 24 should be arranged for vertical movement within the cell so that a desired spacing can be maintained between the anode and cathode notwithstanding the anode being consumed by evolving oxygen.
  • a packed bed 41 of loose elements 42 is positioned in the cell, in the molten aluminum pool 30.
  • These elements are formed of a substance substantially non-wettable by aluminum.
  • the elements are maintained in the molten aluminum at a level at or below the interface 36 between the molten aluminum and molten cryolite, the depth to which the elements are packed being substantially uniform across the cell.
  • the elements should be notfurtherthan 5 centimeters from the interface, but should not extend substantially above the interface, particularly where the elements 42 may be subject to aggressive attack by the cryolite.
  • the packed bed elements can be of any shape. It is preferred that the shapes provide, when packed, interstices through the packed bed whereby aluminum can fill gaps in the packing to maintain uniform electrical conductivity through the packed pool of aluminum. Particularly, packing in the formed of berl saddles, Raschig rings, Intaox saddles, and equiaxed shapes such as cylinders and spheres are much preferred; however randomly shaped packing, blocks or bricks may be utilized.
  • the packing is fabricated from a material substantially non-wettable by molten aluminum, preferably porous, with alumina, AI 2 0 3 , being much preferred. Since alumina is soluble in the molten cryolite, and since aluminum is being electrolyzed within the cell from alumina dissolved in the cryolite layer 32, it is important that the alumina packing be maintained reliably covered with aluminum to prevent consumption of the packing-covering is conveniently accomplished by maintaining the packing virtually continuously beneath the interface when the packing is non- wettable by aluminum, a substantial aluminum thickness is required to assure non-contact with cryolite. However should portions of the aluminum, non-wettable packing protrude from the molten aluminum but be coated with molten aluminum, the packing would thereby be protected. Being covered by molten aluminum shields the packing elements from aggressive attack by the cryolite.
  • Shielding can be accomplished by making the normally aluminum non-wettable packing wettable by molten aluminum at operating temperatures within the cell. Wettability is accomplished by providing the otherwise nonwettable packing with a surface coating of a wetting agent and a solubility suppressor for the wetting agent. This coating can include any of a variety of elemental materials known for making aluminum non-wettable materials wettable by aluminum. As wetting agent Zr, Hf, Si, Mg, V, Cr, Nb, Ca and Ti are suitable with Ti being substantially preferred in the practice of the invention.
  • Elements substantially suppressing the solubility of the wetting agents in molten aluminum are suitable for use as solubility suppressors.
  • solubility suppressors typically boron, carbon and nitrogen are useful with boron being much preferred.
  • the coating applied then is TiB 2 , but the practice detailed applies equally to other wetting agents and solubility suppressors.
  • the surface coating can be applied to the packing by a variety of methods.
  • the packing can be soaked in a slurry of titanium hydride and morphous, powdered boron in polyvinyl alcohol, and then fired at 800-1500 0 C for 1 to 25 hours.
  • titanium can be applied by electroless metallidization techniques in a fused salt bath.
  • the titanium coated packing is then packed in boron powder for 1 to 25 hours at 800 to 1200°C.
  • the titanium may be sputtered onto the packing.
  • boridization in boron powder may be eliminated by sputtering TiB 2 directly onto the packing.
  • TiB 2 may also be applied directly to the packing by vapor deposition. Alternately a slurry of Ti0 2 and B 2 0 3 may be spray applied to the surface and reduced.
  • the packing can be soaked in aluminum containing titanium and boron for 1 to 2 weeks to apply the coating.
  • Titanium may be present as Ti, Ti0 2 or TiB 2 for example, while boron may be present as B Z O 3 , B°for example where the packing has been molded from a refractory material such as alumina, titanium and boron compounds such as Ti0 2 and B 2 0 1 or TiB 2 may be molded with the packing.
  • the boron and titanium will tend to migrate to the surface of the packing to provide the desired coating.
  • Wetting of alumina or other suitable substrate can be achieved using this procedure of soaking in aluminum containing wetting agent and solubility suppressor outside of the aluminum electrowinning cell, in which case the coated wettable packing is transferred to the cell.
  • the packing or substrate can be made wettable in-situ by soaking in aluminum containing wetting agent and solubility suppressor in the aluminum electrowinning cell.
  • the coating can be produced in-situ through the aluminothermic reduction of titanium oxide and boron oxide coatings on alumina or other substrates.
  • the formation of a surface coating of TiB 2 combined with alumina results through this in-situ reaction and wetting by aluminum is achieved. If desired, this in-situ reaction coating can be done by contact with molten aluminum in the electrowinning cell.
  • An average coating thickness of between 5.0 angstroms and 100 microns is preferable, with coatings in excess of about 10 angstroms being much preferred.
  • the coating need not be continuous; continuous coatings delivering only marginally superior wettability over noncontinuous coatings.
  • the inclusion of the wetting agent and solubility suppressor is intended to produce a surface effect only. Total inclusion of substances such as TiB 2 generally will not exceed about 5% and usually substantially below 1% by weight. Unless the substrate being coated is electrically conductive, the coated substrate remains relatively electrically non-conductive.
  • the TiB 2 coating permits virtually instantaneous wetting of the substrate. It is further believed that the TiB 2 coating functions to provide a surfactant permitting molten aluminum to penetrate pores of a coated structure. A partially aluminum filled porous structure surface results, having advantageous physical characteristics over a mere wetted surface. Ti and B dissolving from the surface coating penetrate the pores with the molten aluminum, permitting in surfactant fashion the passage of molten aluminum into pores otherwise inaccessible to the molten aluminum by reason of surface tension. To achieve this result, both the substrate surface and the TiB 2 coating should be porous, permitting infiltration into substrate pores.
  • Titanium and boron present in the coating are, together, marginally soluble in molten aluminum. Once immersed in molten aluminum, the coating therefore tends to dissolve into the molten aluminum unless the molten aluminum is near or above saturation with titanium and boron.
  • titanium is soluble in molten aluminum to about 50 parts per million (ppm) and boron to about 20 ppm. Therefore it is desirable that molten aluminum present in the cell be maintained saturated with titanium and boron by the addition of compounds containing them.
  • existing aluminum electrowinning cells are equipped for introducing additives, however any suitable or conventional method for introducing the Ti and B would suffice, including the introduction of TiB 2 .
  • packing has been shown as the cell component being fabricated from a nonaluminum wettable material, other components are suitable candidates for fabrication using these wettability techniques.
  • weirs for overflowing molten aluminum from the cell, and current feeders may be fabricated using the technique of the instant invention from aluminum nonwettable materials.
  • Other applications within the cell will become apparent upon reflection.
  • a number of suitable or conventional materials substantially nonwettable by aluminum are available for use in the instant invention. These materials, because of the relatively elevated temperature they must withstand in an aluminum electrolysis cell, are primarily refractory materials including alumina, aluminum nitride, AION, SiAION, boron nitride, silicon nitride, aluminum borodes such as AIB 121 silicon carbides, alkali earth metal zirconates and aluminates such as calcium zirconate, barium zirconate, and magnesium aluminate, and mixtures of these materials. Alumina is preferred.
  • wettable what is meant is a contact angle between the coated substrate and molten aluminum of less than 90°; nonwettable being a contact angle in excess of 90°.
  • nonwettable substrates such as alumina, coated according to the method of the instant invention allow aluminum to spread over the substrate surface, indicating a contact angle of about 30° or less.
  • an alumina substrate normally subject to some aggressive attack by molten cryolite even when immersed in an aluminum pool within an aluminum electrowinning cell, can be coated and immersed in molten aluminum within the cell with small concern for its dimensional integrity.
  • Titanium diboride was coated onto Diamonite@ alumina balls. These balls were supplied by Diamonite Products Manufacturing Incorporated and were comprised of approximately 1 to 3 percent silicon dioxide and the balance alumina. These balls were first etched in a molten salt mixture of 49 percent NaOH, 49 percent KOH, and 2 percent NaF at 180°C for approximately 1 hour. Following etching, these balls were solvent degreased and coated with titanium by immersion in a molten salt mixture of 203.6 grams of KCI, 165.2 grams of NaCI, 15.2 grams of CaCI 2 and 16.7 grams of TiH2. Coating was conducted at approximately 1000°C for four hours.
  • the balls were then washed and dried. Following drying the balls were packed into a boron powder bed and boridized using well known techniques at 1000°C for 48 hours in an argon atmosphere scrubbed of residual oxygen by passage over hot titanium. Following boridization, the balls were placed in a ball mill including alumina beads and agitated to remove excess surface boron from the balls by abrasion.
  • the balls were then each placed in an alumina crucible with 30 grams of aluminum and 3-5 grams cryolite.
  • the crucible was evacuated and heated to 1000°C for 4-8 weeks. While under heat the crucible was maintained under an argon purge, the argon being scrubbed of oxygen by passage over hot titanium at 800-900°C.
  • the balls were inspected and found to be wetted by aluminum. Only extremely limited grain boundary corrosion was noted in a TiB 2 coating that averaged only 10-20 micrometers in thickness. Additionally, trace amounts of titanium were found in the alumina crucible, primarily in the pores. These pores were also found to be at least partially wetted by aluminum with a small quantity of the aluminum being found in pores of the alumina crucible. Specifically with respect to the balls, the interface between the TiB 2 coating and the alumina substrate was found to be intact, and showing no evidence of grain boundary corrosion of TiB 2 was observed. In the balls, a contrast gradation was observed in the alumina substrate which was attributed to filling of the pores with aluminum.
  • Example 1 was repeated with the exception that the balls were not solvent degreased. The results were essentially identical.
  • the etched alumina materials were rinsed in distilled water and stored in methyl alcohol. Each was then coated with titanium for four hours at approximately 1000°C under an argon atmosphere scrubbed of oxygen by passage over hot titanium in a bath comprising 796 grams of KCI, 640 grams of NaCI, 59 grams of CaCI, and 65 grams of TiH 2 .
  • honeycombs and balls surrounded by the treated alumina tube sections and encased in aluminum were subjected to 10 hour polarization tests.
  • Each honeycomb or ball in its alumina tube section was placed on a carbon disc 6 centimeters in diameter by 0.7 centimeters thick resting on a 6 centimeter diameter alumina pallet positioned in the bottom of a 750 milliliter alumina crucible.
  • a molybdenum rod encased in boron nitride was employed as a cathodic current feeder connecting to the carbon disc and alumina pallet to the negative pole of a source of electrical current.
  • the cell was completed by positioning a carbon cylinder 3 centimeters in diameter and 3; centimeters in length into the crucible for employ as an anode.
  • the cell was charged with 600 grams of 10 percent alumina in cryolite. 4.81 amperes were passed between anode and cathode for 10 hours. 3 centimeters of molten aluminum was maintained in the cell so that the honeycombs or balls remained immersed at all time.
  • each aluminum cathode was disassembled and the coating alumina honeycomb or ball was examined.
  • the surrounding alumina tube section had fractured. Examination of the honeycomb revealed that the aluminum surrounding the honeycomb had protected the alumina honeycomb from attack while under polarization.
  • the cell voltage was approximately 2.47 volts, and the spacing between the anode and the aluminum cryolite interface within the cell was 2.5 to 2.7 centimeters.
  • Example 3 was repeated except that provision was made for draining aluminum from the crucible as it formed so that the honeycomb or ball were bathed in cryolite, the carbon disc was replaced with a titanium diboride disc of equal dimension, and the honeycomb or balls were placed directly on the titanium diboride disc without benefit of the surrounding treated tube section.
  • the honeycomb or ball were each encased in aluminum upon insertion into the cell. That aluminum melted upon cell start-up and was withdrawn from the crucible.
  • the cryolite charged to the cell was electrolyzed to produce molten aluminum under electrolysis conditions identical to Example 3 except that the anode was maintained at approximately 2.5 centimeters distance from upper portions of the honeycomb or ball as arranged in the crucible cell.
  • each cell was cooled and each honeycomb or ball was removed for examination.
  • These objects notwithstanding their direct contact with molten cryolite during electrolysis, were found to have a 100 to 500 micron film upon all surfaces.
  • the alumina substrates of each honeycomb or ball were not attacked.
  • a cylindrical solid section of AIB 12 was split longitudinally to yield a solid half cylinder.
  • the half cylinder was degreased with propanol.
  • the degreased half of the cylinder was immersed in a mixture of 20.36 grams KCI, 16.52 grams NaCI, 1.52 grams CaC1 2 , and 2 grams of titanium hydride at approximately 1000°C under an argon inerted atmosphere scrubbed of oxygen by passage over hot titanium. Immersion was contained for four hours.
  • the half cylinder was then boridized in a manner identical to that of Example 1. Upon inspection, a 15 micron coating of titanium diboride was found to be present on the surface of the half cylinder.
  • the half cylinder was placed in a 750 milliliter alumina crucible, containing a titanium diboride ring filled with aluminum. The half cylinder was inserted into the ring so that a portion of the half cylinder protruded above the aluminum contained within the titanium diboride ring. The balance of the crucible was filled with cryolite. The crucible was heated to 1000°C for 2 hours. After 2 hours the treated half cylinder was found to be coated uniformly with aluminum, even those portions protruding from the titanium diboride ring, into cryolite floating atop molten aluminum contained in the TiB 2 ring.
  • Example 5 was repeated for BN with essentially identical results.

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Claims (7)

1. Cellule de production d'aluminium à sel fondu, comprenant un constituant mouillable par l'aluminium et exposé à de l'aluminium fondu dans la cellule, ledit constituant étant essentiellement formé d'une matière non mouillable par l'aluminium mais rendue mouillable par l'aluminium en la revêtant d'un composé renfermant les éléments d'un agent mouillant et d'un inhibiteur de solubilité pour cet agent mouillant, caractérisée en ce que l'aluminium fondu contient ledit agent mouillant et ledit inhibiteur de solubilité à des concentrations voisines de la saturation.
2. Cellule selon la revendication 1, caractérisée en ce que le revêtement présente une épaisseur comprise entre environ 5 angstrôms et environ 100 micromètres.
3. Cellule selon la revendication 1 ou 2, caractérisée en ce que ledit revêtement est continu.
4. Cellule selon l'une quelconque des revendications précédentes, caractérisée en ce que l'agent mouillant est du titane et l'inhibiteur de solubilité du bore.
5. Cellule selon l'une quelconque des revendications précédentes, caractérisée en ce que le constituant devant être amené à rester mouillable par l'aluminium est formé d'une matière choisie parmi l'alumine, le nitrure d'aluminium, AION, SiAION, le nitrure de bore, le nitrure de silicium, des carbures de silicium, des borures d'aluminium, des zirconates et aluminates de métaux alcalino-terreux ou leurs mélanges.
6. Procédé pour maintenir la mouillabilité par l'aluminium d'un constituant d'une cellule de production d'aluminium, lequel constituant est formé essentiellement d'une matière non mouillable par l'aluminium qui a été rendue mouillable par l'aluminium en la revêtant d'un composé contenant les éléments d'un agent mouillant et d'un inhibiteur de solubilité pour cet agent mouillant, caractérisé en ce que l'agent mouillant et l'inhibiteur de solubilité sont conservés dans l'aluminium fondu à des concentrations voisines de la saturation.
7. Procédé selon la revendication 6, caractérisé en ce que le revêtement du constituant est formé in situ.
EP83810197A 1982-05-10 1983-05-09 Matériaux mouillables par l'aluminium Expired EP0094353B1 (fr)

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Application Number Priority Date Filing Date Title
AT83810197T ATE32107T1 (de) 1982-05-10 1983-05-09 Aluminium benetzbare materialien.

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US37662982A 1982-05-10 1982-05-10
US376629 1982-05-10

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EP0094353A2 EP0094353A2 (fr) 1983-11-16
EP0094353A3 EP0094353A3 (en) 1984-03-07
EP0094353B1 true EP0094353B1 (fr) 1988-01-20

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EP (1) EP0094353B1 (fr)
JP (1) JPS58207385A (fr)
AT (1) ATE32107T1 (fr)
AU (1) AU572092B2 (fr)
CA (1) CA1233781A (fr)
DE (1) DE3375409D1 (fr)
NO (1) NO831651L (fr)

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WO1983001465A1 (fr) * 1981-10-23 1983-04-28 Alusuisse Cathode de cellule d'electrolyse de masse en fusion pour la preparation d'aluminium

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CA1233781A (fr) 1988-03-08
EP0094353A2 (fr) 1983-11-16
DE3375409D1 (en) 1988-02-25
JPS58207385A (ja) 1983-12-02
AU1439083A (en) 1983-11-17
EP0094353A3 (en) 1984-03-07
NO831651L (no) 1983-11-11
AU572092B2 (en) 1988-05-05
ATE32107T1 (de) 1988-02-15

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