Abstract: The present invention provides a simple method for producing an electrode having improved oxygen evolution reaction (OER) activity without a need for catalyst coating and an electrode produced by this production method. The method is a method for producing an electrode including a step of subjecting an electrically conductive substrate comprising a nickel alloy comprising 30 to 70% by mass of Ni and 30 to 70% by mass of Fe, provided that Ni+Fi=100% by mass, to a thermal treatment, and a step of etching the thermally treated electrically conductive substrate with an etchant comprising at least any acid of an organic acid and a weak inorganic acid. The electrode is an electrode that is produced by this production method and that is useful as an oxygen evolution anode or the like.

Abstract: A metallic oxygen evolving anode for electrowinning aluminum by decomposition of alumina dissolved in a cryolite-based molten electrolyte, and operable at anode current densities of 1.1 to 1.3 A/cm2, comprises an alloy of nickel, iron, manganese, optionally copper, and silicon. Preferably, the alloy is composed of 64-66 w % Ni; Iron; 25-27 w % Fe; 7-9 w % Mn; 0-0.7 w % Cu; and 0.4-0.6 w % Si. The weight ratio Ni/Fe is in the range 2.1 to 2.89, preferably 2.3 to 2.6, the weight ratio Ni/(Ni+Cu) is greater than 0.98, the weight ratio Cu/Ni is less than 0.01, and the weight ratio Mn/Ni is from 0.09 to 0.15. The alloy surface can comprise nickel ferrite produced by pre-oxidation of the alloy. The alloy, optionally with a pre-oxidized surface, can be coated with an external coating comprising cobalt oxide CoO.

Abstract: Compositions for making wettable cathodes to be used in aluminum electrolysis cells are disclosed. The compositions generally include titanium diboride (TiB2) and metal additives. The amount of selected metal additives may result in production of electrodes having a tailored density and/or porosity. The electrodes may be durable and used in aluminum electrolysis cells.

Abstract: An anode for electrowinning of aluminium from alumina comprises a cobalt-containing metallic outer part that is covered with an integral oxide layer containing predominantly cobalt oxide CoO. The integral oxide layer can be formed by surface oxidation of cobalt from the metallic outer part before use.

Abstract: A cell for electrowinning a metal, in particular aluminium, from a compound thereof dissolved in an electrolyte (30) comprises an anode (40) and a cathode (10,11) that contact the electrolyte (30), the cathode (10,11) being during use at a cathodic potential for reducing thereon species of the metal to be produced from the dissolved compound. The electrolyte (30) further contains species of at least one element that is liable to contaminate the product metal (20) and that has a cathodic reduction potential which is less negative than the cathodic potential of the metal to be produced. The cell further comprises a collector (50) for removing species of such element (s) from the electrolyte (30).

Abstract: An anode for electrowinning aluminium comprises an electrically conductive substrate that is covered with an applied electrochemically active coating comprising a layer that contains predominantly cobalt oxide CoO. The CoO layer can be connected to the substrate through an oxygen barrier layer, in particular containing copper, nickel, tungsten, molybdenum, tantalum and/or niobium.

Abstract: A cell for electrowinning aluminium from alumina, comprises: a metal-based anode having an electrochemically active outer part comprising a layer that contains predominantly cobalt oxide CoO; and a fluoride-containing molten electrolyte in which the active anode surface is immersed. The electrolyte is at a temperature below 950° C., in particular in the range from 910° to 940° C. The electrolyte consists of: 6.5 to 11 weight. % dissolved alumina; 35 to 44 weight % aluminium fluoride; 38 to 46 weight % sodium fluoride; 2 to 15 weight % potassium fluoride; 0 to 5 weight % calcium fluoride; and 0 to 5 weight % in total of one or more further constituents.

Abstract: Current busbar for anode or cathode for use in production of aluminium from alumina in an electrolysis bath in an electrolysis cell, comprising ends or sections that during operation shall be within the electrode body are formed as horizontally oriented conical bodies and cylindrical or conical grooves with largest horizontal cross section dimension within said grooves, such that by sliding in correspondingly formed cooper rails on the external parts of the busbar, said bodies and rails are releasable joined.

Abstract: The present invention relates to a dimensionally stable oxygen-evolving anode for use in an electrolytic cell for the production of aluminium. The anode comprises of a container made from an alloy comprising aluminium and at least one metal more noble than aluminium; a fluid bath in the bottom of the container having the ability to dissolve aluminium, said fluid having a density that is higher than the density of molten aluminium at the operating temperature of the cell, a pool of molten aluminium floating on top of the fluid bath in the bottom of the container; a refractory layer arranged on the inner sidewalls of the container at least in the area of the pool of molten aluminium, said refractory layer protecting the molten aluminium from contacting the inner sidewalls of the container.

Abstract: A method for electrolytic production of aluminium metal from an electrolytic (3) including aluminium oxide, by performing electrolysis, with at least one inert anode (1) and at least one cathode (2) thus forming part of an electorwinning cell. The anode evolves oxygen gas and the cathode has aluminium discharged onto it in the electrolysis process, where the oxygen gas enforces an electrolyte flow pattern. The oxygen gas is directed to flow into anode grooves and is drained away from the interpolar room, thereby establishing an electrolyte flow pattern between the electrodes (1) and (2) and between over the anodes (1). The invention also concerns and anode assembly and an electrowinning cell.

Abstract: An anode for the electrowinning of aluminium by the electrolysis of alumina in a molten fluoride electrolyte has an electrochemically active integral outside oxide layer obtainable by surface oxidation of a metal alloy which consists of 20 to 60 weight % nickel; 5 to 15 weight % copper; 1.5 to 5 weight % aluminium; 0 to 2 weight % in total of one or more rare earth metals, in particular yttrium; 0 to 2 weight % of further elements, in particular manganese, silicon and carbon; and the balance being iron. The metal alloy of the anode has a copper/nickel weight ratio in the range of 0.1 to 0.5, preferably 0.2 to 0.3.

Abstract: The purpose of the invention is a process for making a solid part designed to form all or part of an anode for the production of aluminium by fused bath electrolysis, containing a cermet formed from at least one metallic oxide such as a mixed oxide with spinel structure, and at least one metallic phase, in which a mixed oxide is used containing a metal R in the form of a cation in its chemical structure, the said metal R being fully or partly reducible by a reduction operation during the manufacturing process, so as to form all or part of the said metallic phase. This process can provide a cermet with a uniform distribution of fine metallic particles.

Abstract: A method of forming a dense and crack-free hematite-containing protective layer on a metal-based substrate for use in a high temperature oxidising and/or corrosive environment comprises applying onto the substrate a particle mixture consisting of: 60 to 99 95 weight %, in particular 70 to 95 weight % such as 75 to 85 weight %, of hematite with or without iron metal and/or ferrous oxide; 1 to 25 weight %, in particular 5 8 to 20 weight % such as 8 to 15 weight %, of nitride and/or carbide particles, such as boron nitride, aluminium nitride or zirconium carbide particles; and 0 to 15 weight %, in particular 5 to 15 weight %, of one or more further constituents that consist of at least one metal or metal oxide or a heat-convertible precursor thereof.

Abstract: A method of manufacturing a component, in particular an aluminium electrowinning anode, for use at elevated temperature in an oxidising and/or corrosive environment comprises: applying onto a metal-based substrate layers of a particle mixture containing iron oxide particles and particles of a reactant-oxide selected from titanium, yttrium, ytterbium and tantalum oxides; and heat treating the applied layers to consolidate by reactive sintering of the iron oxide particles and the reactant-oxide particles to turn the applied layer into a protective coating made of a substantially continuous reacted oxide matrix of one or more multiple oxides of iron and the metal from the reactant-oxide. The metal-based substrate comprises at its surface during the heat treatment an integral anchorage-oxide of at least one metal of the substrate.

Abstract: A material suitable for use as the active anode surface in the electrolytic reduction of alumina to aluminium metal defined by the formula: A1+xB1+?CdO4 where A is a divalent cation or a mixture of cations with a relative preference for octahedral coordination, B is a trivalent cation or mixture of cations with a relative preference for tetrahedral coordination, C is a trivalent cations with a relative preference for octahedral coordination or a four-valent cation with a relative preference for octahedral coordination, O is the element oxygen: When C is trivalent x=0, 0.8<d<1, ?<0.2 and x+d+d is essentially equal to 1. When C is four-valent 0.4<x<0.6, 0.4<d<0.6, ?<0.2 and x+d+? is essentially equal to 1.

Abstract: A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte, the method comprising the steps of providing a molten salt electrolyte at a temperature of less than 900° C. having alumina dissolved therein in an electrolytic cell having a liner for containing the electrolyte, the liner having a bottom and walls extending upwardly from said bottom. A plurality of non-consumable Cu—Ni—Fe anodes and cathodes are disposed in a vertical direction in the electrolyte, the cathodes having a plate configuration and the anodes having a flat configuration to compliment the cathodes. The anodes contain apertures therethrough to permit flow of electrolyte through the apertures to provide alumina-enriched electrolyte between the anodes and the cathodes. Electrical current is passed through the anodes and through the electrolyte to the cathodes, depositing aluminum at the cathodes and producing gas at the anodes.

Abstract: Ceramic inert anodes useful for the electrolytic production of aluminum are disclosed. The inert anodes comprise oxides of Ni, Fe and Al. The Ni—Fe—Al oxide inert anode materials have sufficient electrical conductivity at operation temperatures of aluminum production cells, and also possess good mechanical stability. The Ni—Fe—Al oxide inert anodes may be used to produce commercial purity aluminum.

Abstract: An anode of a cell for the electrowinning of aluminium comprises a nickel-iron alloy substrate having a nickel metal rich outer portion with an electrolyte pervious integral nickel-iron oxide containing surface layer which adheres to the nickel metal rich outer portion of the nickel-iron alloy and which in use is electrochemically active for the evolution of oxygen. The oxide surface layer has a thickness such that, during use, the voltage drop therethrough is below the potential of dissolution of nickel-iron oxide. The nickel metal rich outer portion may contain cavities some or all of which, after oxidation, are partly or completely filled with iron oxides to form iron oxide containing inclusions.

Abstract: A cell for the electrowinning of aluminium comprising one or more anodes (10), each having a metal-based anode substrate, for instance comprising a metal core (11) covered with an metal layer 12, an oxygen barrier layer (13), one or more intermediate layers (14; 14A, 14B) and an iron layer (15). The anode substrate is covered with an electrochemically active transition metal oxide layer, in particular an iron oxide-based outside layer (16) such as a hematite-based layer, which remains dimensionally stable during operation in a cell by maintaining in the electrolyte a sufficient concentration of iron species and dissolved alumina. The cell operating temperature is sufficiently low so that the required concentration of iron species in the electrolyte (5) is limited by the reduced solubility of iron species in the electrolyte at the operating temperature, which consequently limits the contamination of the product aluminium by iron to an acceptable level.

Abstract: An anode of a cell for the electrowinning of aluminium comprises a nickel-iron alloy substrate having an openly porous nickel metal rich outer portion whose surface is electrochemically active. The outer portion is optionally covered with an external integral nickel-iron oxide containing surface layer which adheres to the nickel metal rich outer portion of the nickel-iron alloy and which in use is pervious to molten electrolyte. During use, the nickel metal rich outer portion contains cavities some or all of which are partly or completely filled with iron and nickel compounds, in particular oxides, fluorides and oxyfluorides.

Abstract: An anode of a cell for the electrowinning of aluminium has a nickel-iron alloy outer portion which during use is covered with an integral iron-based oxide surface layer. The nickel-iron alloy outer portion comprises one or more rare earth metals that are substantially insoluble in nickel and iron. These rare earth metals are present in the outer portion in an amount which provides during use controlled diffusion of iron from the outer portion to the integral iron-based oxide surface layer.

Abstract: Ceramic inert anodes useful for the electrolytic production of aluminum are disclosed. The inert anodes comprise an oxide of Ni and Fe having a controlled Ni/(Ni+Fe) mole ratio which results in a single-phase structure at the operation temperatures of aluminum production cells. The Ni and Fe oxide material may also have a single-phase structure at the sintering temperature of the material. The single-phase inert anode materials maintain sufficient electrical conductivity at the operating temperatures of the cell, and also possess good mechanical stability.

Abstract: Ceramic inert anodes useful for the electrolytic production of aluminum are disclosed. The inert anodes comprise oxides of Ni, Fe and Al. The Ni—Fe—Al oxide inert anode materials have sufficient electrical conductivity at operation temperatures of aluminum production cells, and also possess good mechanical stability. The Ni—Fe—Al oxide inert anodes may be used to produce commercial purity aluminum.

Abstract: A method of producing aluminum in a low temperature electrolytic cell containing alumina dissolved in an electrolyte. The method comprises the steps of providing a molten electrolyte having alumina dissolved therein in an electrolytic cell containing the electrolyte. A non-consumable anode and cathode is disposed in the electrolyte, the anode comprised of Cu—Ni—Fe alloys having single metallurgical phase. Electric current is passed from the anode, through the electrolyte to the cathode thereby depositing aluminum on the cathode, and molten aluminum is collected from the cathode.

Abstract: A method of producing aluminum from alumina in an electrolytic cell including using a cathode comprised of a base material having low electrical conductivity and wettable with molten aluminum to form a reaction layer having a high electrical conductivity on said base layer and a cathode bar extending from said reaction layer through said base material to conduct electrical current from said reaction layer.

Abstract: A method of producing aluminum in an electrolytic cell comprising the steps of providing an anode in a cell, preferably a non-reactive anode, and also providing a cathode in the cell, the cathode comprised of a base material having low electrical conductivity reactive with molten aluminum to provide a highly electrically conductive layer on the base material. Electric current is passed from the anode to the cathode and alumina is reduced and aluminum is deposited at the cathode. The cathode base material is selected from boron carbide, and zirconium oxide.

Abstract: A method of producing aluminum in a low temperature electrolytic cell containing alumina dissolved in an electrolyte. The method comprises the steps of providing a molten electrolyte having alumina dissolved therein in an electrolytic cell containing the electrolyte. A non-consumable anode and cathode is disposed in the electrolyte, the anode comprised of Cu—Ni—Fe alloys containing 0.1 to 5 wt. % carbon and incidental elements and impurities. Electric current is passed from the anode, through the electrolyte to the cathode thereby depositing aluminum on the cathode, and molten aluminum is collected from the cathode.

Abstract: An electrolytic cell for producing aluminum from alumina having a reservoir for collecting molten aluminum remote from the electrolysis.

Abstract: Electrolysis of alumina dissolved in a molten salt electrolyte employing inert anode and cathodes, the anode having a box shape with slots for the cathodes.

Abstract: A process for the electrowinning of aluminium from alumina dissolved in a fluoride-based molten electrolyte in a cell operating at reduced temperature, typically below 870° C., utilising nickel-alloy based anodes, in particular nickel-iron alloy anodes. The electrolyte contains AlF3 in such a high concentration, usually above 20 weight %, in addition to cryolite, that fluorine-containing ions rather than oxygen ions are oxidised on the anodes. However, only oxygen is evolved, the evolved oxygen being derived from the dissolved alumina present near the anodes. The anodes may be porous at the surface so as to provide a high active surface area for operation at low current density.

Abstract: A cell of advanced design for the production of aluminium by the electrolysis of an aluminium compound dissolved in a molten electrolyte, has a cathode (30) of drained configuration, and at least one non-carbon anode (10) facing the cathode both covered by the electrolyte (54). The upper part of the cell contains a removable thermic insulating cover (60) placed just above the level of the electrolyte (54). Preferably, the cathode (30) comprises a cathode mass (32) supported by a cathode carrier (31) made of electrically conductive material which serves also for the uniform distribution of electric current to the cathode mass (32) from current feeders (42) which connect the cathode carrier (31) to the negative busbars.

Abstract: A method of inhibiting dissolution of a transition metal alloy anode (40) of an aluminium electrowinning cell comprises providing a sodium-inert layer (11,20,50,50′) on a sodium-active cathodic cell material (15), such as carbon, and electrolysing alumina dissolved in a sodium ion-containing molten electrolyte (30). Aluminium ions rather than sodium ions are cathodically reduced on the sodium-inert layer to inhibit the presence in the molten electrolyte (30) of soluble cathodically-produced sodium metal that constitutes an agent for chemically reducing the anode's transition metal oxides and anodically evolved oxygen, thereby inhibiting reduction of the anode's transition metal oxides by sodium metal and maintaining the evolved oxygen at the anode at a concentration such as to produce at the alloy/oxide layer interface stable and coherent transition metal oxides having a high level of oxidation.

Abstract: A method of producing aluminum in a low temperature electrolytic cell containing alumina dissolved in an electrolyte. The method comprises the steps of providing a molten electrolyte having alumina dissolved therein in an electrolytic cell containing the electrolyte. A non-consumable anode and cathode is disposed in the electrolyte, the anode comprised of Cu—Ni—Fe alloys containing 0.1 to 5 wt. % carbon and incidental elements and impurities. Electric current is passed from the anode, through the electrolyte to the cathode thereby depositing aluminum on the cathode, and molten aluminum is collected from the cathode.

Abstract: A solid cryolite/alumina mixture is used as the anode in an electrolytic aluminum winning process. The mixture may be used in the form of a crust formed on the electrolytic cell.

Abstract: A method of manufacturing an anode for use in a cell for the electrowinning of aluminium comprises oxidising before cell operation an iron-nickel alloy substrate in an oxygen-containing atmosphere, such as air, at a temperature which is at least 50° C., preferably 100° C., above the operating temperature of the cell to form on the surface of the iron-nickel substrate a coherent and adherent iron oxide-containing outer layer, in particular a hematite-containing layer having a limited ionic conductivity for oxygen ions and acting as a partial barrier to monoatomic oxygen. The outer layer is electrochemically active for the oxidation of oxygen ions and reduces also diffusion of oxygen to the iron-nickel alloy substrate when the anode is in use.

Abstract: A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte, the method comprising the steps of providing a molten salt electrolyte at a temperature of less than 900° C. having alumina dissolved therein in an electrolytic cell having a liner for containing the electrolyte, the liner having a bottom and walls extending upwardly from said bottom. A plurality of non-consumable anodes and cathodes are disposed in a vertical direction in the electrolyte, the cathodes having a plate configuration and the anodes having a flat configuration to compliment the cathodes. The anodes contain apertures therethrough to permit flow of electrolyte through the apertures to provide alumina-enriched electrolyte between the anodes and the cathodes. Electrical current is passed through the anodes and through the electrolyte to the cathodes, depositing aluminum at the cathodes and producing gas at the anodes.

Abstract: A solid cryolite/alumina mixture is used as the anode in an electrolytic aluminum winning process. The mixture may be used in the form of a crust formed on the electrolytic cell.

Abstract: A cell for the electrowinning of aluminium comprising one or more anodes (10), each having a metal-based anode substrate, for instance comprising a metal core (11) covered with an metal layer 12, an oxygen barrier layer (13), one or more intermediate layers (14; 14A, 14B) and an iron layer (15). The anode substrate is covered with an electrochemically active transition metal oxide layer, in particular an iron oxide-based outside layer (16) such as a hematite-based layer, which remains dimensionally stable during operation in a cell by maintaining in the electrolyte a sufficient concentration of iron species and dissolved alumina. The cell operating temperature is sufficiently low so species and dissolved alumina.

Abstract: An anode of a cell for the electrowinning of aluminium comprises an iron-nickel alloy body or layer whose surface is oxidised to form a coherent and adherent outer iron oxide-based layer, in particular hematite, the surface of which is electrochemically active for the oxidation of oxygen ions and which reduces diffusion of oxygen from the electrochemically active surface into the iron-nickel alloy body or layer. The anode may be kept dimensionally stable during cell operation by maintaining a sufficient amount of dissolved alumina and iron species in the electrolyte to prevent dissolution of the outer oxide layer of the or each anode and by reducing the electrolyte operating temperature to limit dissolution of iron and by reducing the electrolyte operating temperature to limit dissolution of iron species in the electrolyte.

Abstract: This invention relates to the use of bubble-driven flow to enhance the dissolution and distribution of alumina in an aluminum electrolysis cell operating with inert anodes. By harnessing the driving force of bubbles rising along the sides of a sloped anode to induce circulation in a cell and by using a group of anodes to amplify the effect, alumina distribution can be maintained close to or at saturation without formation of muck/sludge. Alumina fed through point feeders at specific locations can be distributed throughout the entire cell rather than sinking to the bottom of the cell below the feed location. For a given circulation pattern, feeder locations can be optimized.

Abstract: A cell for the electrowinning of aluminum using anodes (10) made from a alloy of iron with nickel and/or cobalt is arranged to produce aluminum of low contamination and of commercial high grade quality. The cell comprises a cathode (20) of drained configuration and operates at reduced temperature without formation of a crust or ledge of solidified electrolyte. The cell is thermally insulated using an insulating cover (65,65a,65b,65c) and an insulating sidewall lining (71). The molten electrolyte (30) is substantially saturated with alumina, particularly on the electrochemically active anode surface, and with species of at least one major metal present at the surface of the nickel-iron alloy based anodes (10). The cell is preferably operated at reduced temperature from 730° to 910° C. to limit the solubility of these metal species and consequently the contamination of the product aluminum.

Abstract: A method of treating an electrolyte for use in the electrolytic reduction of alumina to aluminum employing an anode and a cathode, the alumina dissolved in the electrolyte, the treating improving wetting of the cathode with molten aluminum during electrolysis. The method comprises the steps of providing a molten electrolyte comprised of ALF3 and at least one salt selected from the group consisting of NaF, KF and LiF, and treating the electrolyte by providing therein 0.004 to 0.2 wt. % of a transition metal or transition metal compound for improved wettability of the cathode with molten aluminum during subsequent electrolysis to reduce alumina to aluminum.

Abstract: A method of treating a carbonaceous cell component of an electrolyte cell for the production of aluminum, to impart protection against deterioration during operation of the cell. A liquid suspension of a refractory material dispersed in a lignosulfonate binder solution is prepared and applied as a protective coating to the surface of carbonaceous cell components and allowed to dry.

Abstract: A cermet inert anode having a reduced level of contaminating surface metal is disclosed. Methods for preparing cermet inert anodes and methods for treating cermet inert anodes are also disclosed. The methods generally use an oxidizing agent to convert metals on the surface of the anode to inert oxides and/or to otherwise remove the metal contaminants. The inert anodes of the present invention may be used in electrolytic reduction cells for the production of commercial purity aluminum, as well as other metals.

Abstract: A cermet anode of an electrolytic cell is protected from thermal shock during cell start-up by coating an outer surface portion of the anode with a coating composition comprising carbon or aluminum or a mixture thereof. A particularly preferred coating composition includes an aluminum underlayer adjacent the outer surface portion of the anode, and a carbon overlayer overlying the underlayer. A support structure assembly supporting the cermet anode includes a high alumina ceramic material. In a preferred embodiment, the high alumina ceramic material is protected from thermal shock and corrosion by the coating composition of the invention.

Abstract: A cermet inert anode having a reduced level of contaminating surface metal is disclosed. Methods for preparing cermet inert anodes and methods for treating cermet inert anodes are also disclosed. The methods generally use an oxidizing agent to convert metals on the surface of the anode to inert oxides and/or to otherwise remove the metal contaminants. The inert anodes of the present invention may be used in electrolytic reduction cells for the production of commercial purity aluminum, as well as other metals.

Abstract: A cermet inert anode for the electrolytic production of metals such as aluminum is disclosed. The inert anode comprises a ceramic phase including an oxide of Ni, Fe and M, where M is at least one metal selected from Zn, Co, Al, Li, Cu, Ti, V, Cr, Zr, Nb, Ta, W, Mo, Hf and rare earths, preferably Zn and/or Co. Preferred ceramic compositions comprise Fe2O3, NiO and ZnO or CoO. The cermet inert anode also comprises a metal phase such as Cu, Ag, Pd, Pt, Au, Rh, Ru, Ir and/or Os. A preferred metal phase comprises Cu and Ag. The cermet inert anodes may be used in electrolytic reduction cells for the production of commercial purity aluminum as well as other metals.

Abstract: A method of producing commercial purity aluminum in an electrolytic reduction cell comprising ceramic inert anodes is disclosed. The method produces aluminum having acceptable levels of Fe, Cu and Ni impurities. The ceramic inert anodes used in the process may comprise oxides containing Fe and Ni, as well as other oxides, metals and/or dopants.

Abstract: A non-carbon metal-based anode of a cell for the electrowinning of aluminium comprising an electrically conductive metal substrate resistant to high temperature, the surface of which becomes passive and substantially inert to the electrolyte, and a coating adherent to the metal substrate making the surface of the anode electrochemically active for the oxidation of oxygen ions present at the electrolyte interface. The substrate metal may be selected from nickel, cobalt, chromium, molybdenum, tantalum and the Lanthanide series. The active constituents of the coating are for example oxides such as spinels or perovskites, oxyfluorides, phosphides or carbides, in particular ferrites. The active constituents may be coated onto the substrate from a slurry or suspension containing colloidal material and the electrochemically active material.

Abstract: Carbon-containing components of cells for the production of aluminium by the electrolysis of alumina dissolved in a cryolite-based molten electrolyte are protected from attack by liquid and/or gaseous components of the electrolyte in the form of elements, ions or compounds, by a refractory boride coating applied from a slurry composed of pre-formed particulate refractory boride in a colloidal carrier which is dried and heated to consolidate the coating.