Dimensionally stable anode for molten salt electrowinning and method of electrolysis
AssigneeEltech Systems Corporation
InventorJ. J. Duruz
Life of this patent
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Abstract
The morphology of a coating of Ce oxyfluoride on a conductive substrate is improved by addition of yttrium, lanthanum, praseodymium and/or other rare earth metals. Whereas the pure Ce-oxycompound coating shows cracks which frequently extend throughout the entire thickness of the coating, thus exposing finite portions of the substrate to eventual corrosive attack from the environment, the improved coating including the above doping element(s) comprises a substantially impervious structure. Coatings of this nature may be employed with non-consumable anodes in molten aluminum electrowinning cells or as chemical sensors, corrosion protection and other applications.
Claims14
In an electrowinning cell having a substrate with a coating comprising an oxyfluoride of cerium providing enhanced resistivity against reducing as well as oxidizing cell environments up to temperatures of 1000.degree. C. and higher, characterized by the coating further comprising at least one doping compound of an element selected from the group consisting of yttrium, lanthanum, praseodymium and other rare earth metals, the concentration of the doping compound(s) in the coating being less than 10 w % of the cerium constituents in the coating, the coating having a continuous coherent structure thereby providing a substantially impervious layer on the substrate.
The method of claim 13, characterized by producing aluminum.
A method of producing a continuous, coherent and conductive coating on a conductive substrate, said coating having enhanced resistivity against reducing as well as oxidizing environments up to temperatures of 1000.degree. C. and more, said method being characterized by adding to a cell electrolyte compounds of cerium and at least one doping compound precursor substance containing one or more metals selected from the group consisting of yttrium, lanthanum, praseodymium and other rare earth metals, and passing electrical current therethrough with said coating and substrate under anodic polarization.
Dependencies are inferred from the claim text.