Coating composition for carbon electrodes
AssigneeAluminum Company of America
InventorSiba P. Ray
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Abstract
A method for producing a metal in an electrolysis cell comprising an anode, a carbon cathode, and a chamber containing a metal oxide dissolved in a molten salt bath, said method comprising: coating an outer surface portion of the cathode with a coating composition consisting of a refractory metal, a paint comprising an organic polymeric binder, and aluminum powder, and optionally an organic solvent and an oil; and optionally a boron source; curing the coating composition by heating it to an elevated temperature, producing an aluminum-wettable coating on the cathode outer surface portion; and electrolyzing the metal oxide to a metal bypassing an electric current in the molten salt bath between the anode and the coated cathode.
Claims16
A method for producing a metal in an electrolysis cell comprising an anode, a carbon cathode, and a chamber containing a metal oxide dissolved in a molten salt bath, said method comprising:
- (a) coating an outer surface portion of said cathode with a coating composition consisting of a refractory metal source, a paint comprising an organic polymeric binder and aluminum powder, and optionally an organic solvent and an oil;
- and optionally a boron source:
- (b) curing said coating composition by heating it to an elevated temperature, producing an aluminum-wettable coating on said cathode outer surface portion;
- and
- (c) electrolyzing said metal oxide to a metal by passing an electric current in said molten salt bath between said anode and said coated cathode.
In a method for producing aluminum in an electrolysis cell by passing an electric current between an anode and a coated carbon cathode through a molten salt bath containing dissolved aluminum oxide, the improvement wherein said carbon cathode is coated with a coating composition consisting of:
- (1) about 15-40 vol % of a mixture comprising a refractory metal source and a boron source and having a boron:refractory metal molar ratio of at least about 1.2:1:
- and
- (2) about 60-85 vol % of an aluminum paint comprising an organic polymeric binder selected from the group consisting of alkyd resins, phenolic resins, acrylic resins, polystyrene and casein;
- a solvent and aluminum powder.
Dependencies are inferred from the claim text.