Abstract: An adherent protective coating of a refractory material is produced on the surface of carbonaceous, refractory, ceramic, metallic or other materials serving as components of electrolytic cells operating at high temperature, by applying to such surfaces a well chosen micropyretic reaction layer from a slurry, which when dried is ignited to initiate a self-sustaining micropyretic reaction, along a combustion front, to produce condensed matter forming such refractory protective adherent coating. The slurry is preferably applied in several layers, the first layer(s) to facilitate adherence and the last layer(s) to provide protection, and may contain some preformed non-reactant materials. The electrolytic cells whose components require such coatings are especially those operating at high temperature with a molten salt electrolyte, particularly those for the production of metals, aluminium being the most important.

Abstract: A cell for the electrowinning of aluminum from molten salts has a cell bottom lining consisting partly of a refractory mass (4 ) and partly of carbon bodies (5). At least 30% and preferably 50% or more of the cell bottom area is occupied by the refractory mass (4). The carbon bodies (5) are level with the refractory mass (4) or are recessed therein.

Abstract: A cell for the electrowinning of aluminum from molten salts has a cell bottom lining consisting partly of a refractory mass (4) and partly of carbon bodies (5). At least 30% and preferably 50% or more of the cell bottom area is occupied by the refractory mass (4). The carbon bodies (5) are level with the refractory mass (4) or are recessed therein.

Abstract: An aluminum production cell with a non-conductive cell bottom composed predominantly of alumina (1) has a plurality of vertical current collector plates or posts (3), e.g., of steel protected at their upper ends by a carbon body (4), e.g., a plate, slab or cap which contacts the cathodic pool of molten aluminum (10).

Abstract: A method of electrowinning a metal by electrolysis of a melt containing a dissolved species of the metal to be won using a non-consumable anode having a metal, alloy or cermet substrate and an operative anode surface which is a protective surface coating of cerium oxyfluoride preserved by maintaining in the melt a suitable concentration of cerium, is characterized by using an anode provided with an electronically conductive oxygen barrier on the surface of the metal, alloy or cermet substrate. The barrier layer may be a chromium oxide film on a chromium-containing alloy substrate. Preferably the barrier layer carries a ceramic oxide layer, e.g. of stabilized copper oxide which acts as anchorage for the cerium oxyfluoride.

Abstract: A bipolar electrode for electrowinning aluminum or other metals by electrolysis of a molten salt electrolyte containing a dissolved compound of the metal to be won comprises an anodic and a cathodic surface which are both preserved during operation by dissolution of small amounts of a substance in the electrolyte which is capable of being deposited on either surface at a rate compensating the corrosion thereof during electrolysis. The anodic surface is for example cerium oxyfluoride and the cathodic surface cerium hexaboride, both surfaces being preserved by addition of cerium compounds, such as oxides, fluorides, hydrides etc. to the melt. The cathodic surface may also include titanium diboride on top of or together with cerium hexaboride.

Abstract: A composite material comprises a body, e.g., a slab, of a fused refractory oxycompound (3) having a multiplicity of discrete inclusions such as lumps (1) of an aluminum-wettable RHM in its surface. These bodies are especially useful as aluminum-wettable but non-current carrying components of aluminum reduction cells.

Abstract: A ceramic/metal composite material comprises a surface ceramic coating comprising an oxidized alloy of copper stabilized by being in solid solution with nickel oxide or manganese oxide on a substrate which is an oxidation resistant alloy essentially devoid of copper or any metal which oxidizes more readily than copper. The composite is made by oxidizing a copper-based alloy on a substrate and simultaneously oxidizing the substrate surface to form an oxygen-barrier interface, for example a chromium oxide layer formed on an alloy of chrominum with nickel, iron and/or cobalt. The composite may be used as anode substrate for a cerium oxyfluoride coating used in aluminum electrowinning.

Abstract: A non-consumable anode of the type comprising an oxide ceramic coating on a metal substrate, for molten salt electrolysis, namely the electrowinning of metals such as aluminum, has an electronically-conductive oxygen barrier layer between the oxide ceramic coating and the substrate, the oxygen barrier layer containing chromium oxide. Usually, the oxygen barrier layer is a surface film integral with a chromium-containing alloy substrate, comprising 10 to 30% by weight of chromium, 55 to 90% of nickel, cobalt and/or iron and up to 15% of aluminum, titanium, zirconium, yttrium, hafnium or niobium. The ceramic oxide coating may comprise copper oxide in solid solution with at least one further oxide; nickel ferrite; copper oxide and nickel ferrite; doped, non-stoichiometric or partially substituted spinels; or rare earth metal oxides or oxyfluorides.

Abstract: The present invention provides a ceramic/metal composite material comprising cerium/aluminum mixed oxides as the ceramic phase and an alloy or intermetallic compond of cerium and at least one of aluminum, nickel, iron and cobalt as the metal phase. The ceramic phase may comprise interengaged crystal lattices of ceria and alumina. The material may be a self-sustaining body which may be used as substrate for a dimensionally stable anode in molten sale aluminum electrowinning cells, coated with a protective layer of cerium oxyfluoride in situ during electrolysis in molten cryolite containing cerium ions.