Inert anodes for aluminum electrolysis and method of production thereof

Abstract

An inert anode for Al electrolysis, made of Cu—Ni—Fe—O based materials, comprising Fe in a range between about 10 and 20% by weight, Cu in a range between about 60 and about 80% by weight, Ni in a range between about 20 and about 30% by weight, and oxygen in a range between about 1 and about 3% by weight, and a method for producing the anode, comprising mechanically alloying metallic elements; oxygen doping; and consolidation.

1 . Inert anode for Al electrolysis, made of Cu—Ni—Fe—O based materials, comprising Fe in a range between about 10 and 20% by weight, Cu in a range between about 60 and about 80% by weight, Ni in a range between about 20 and about 30% by weight, and oxygen in a range between about 1 and about 3% by weight. 
     
     
         2 . Inert anode of  claim 1 , comprising about 15% by weight Fe, about 64% by weight Cu, about 20% by weight Ni, and about 1.5% by weight oxygen. 
     
     
         3 . Inert anode of  claim 1 , further comprising at most 5 wt. % by weight rare earth elements. 
     
     
         4 . Inert anode of  claim 1 , further comprising at most 1 wt. % by weight rare earth elements. 
     
     
         5 . Inert anode of  claim 1 , wherein the rare earth elements are ones of Y and Ce. 
     
     
         6 . Inert anodes of  claim 1 , having a rate of corrosion of at most 1 cm/year during electrolysis of aluminum at a temperature of about 700° C. 
     
     
         7 . Inert anodes of  claim 1 , having a rate of corrosion of about 0.8 cm/year during electrolysis of aluminum at a temperature of about 700° C. 
     
     
         8 . Inert anodes of  claim 1 , having a stable potential and a low overvoltage for the reaction of oxygen. 
     
     
         9 . Inert anodes of  claim 1 , having a stable potential and an overvoltage for the reaction of oxygen less than 0.4V at 0.5 A/cm 2 . 
     
     
         10 . A method for producing metallic inert anodes made of Cu—Ni—Fe—O based materials, comprising:
 mechanically alloying metallic elements; 
 oxygen doping; and 
 consolidation. 
 
     
     
         11 . The method of  claim 10 , wherein said mechanically alloying comprises grinding metallic elements under inert atmosphere; and said oxidizing comprises a subsequent grinding of the alloyed elements under O 2  atmosphere. 
     
     
         12 . The method of  claim 10 , wherein said mechanically alloying and said oxygen doping comprise grinding metallic elements and iron oxides particles, the iron oxides particles having a nanometric size. 
     
     
         13 . The method of  claim 10 , wherein said mechanically alloying and said oxygen doping comprise grinding metallic elements and iron oxides particles, the iron oxides particles have a size of at most 100 nm. 
     
     
         14 . The method of  claim 10 , comprising synthetizing an alloy with Fe in a range between about 10 and 20% by weight, Cu in a range between about 60 and about 80% by weight, Ni in a range between about 20 and about 30% by weight, and oxygen in a range between about 1 and about 3% by weight. 
     
     
         15 . The method of  claim 10 , comprising synthetizing an alloy with about 15% by weight Fe, about 64% by weight Cu, about 20% by weight Ni, and about 1.5% by weight oxygen. 
     
     
         16 . The method of  claim 10 , comprising synthetizing a metallic CuNiFe alloy by high energy ball milling of Cu, Ni and Fe powders under Ar atmosphere; and oxidizing the CuNiFe alloy by a subsequent high energy ball milling under O 2  atmosphere. 
     
     
         17 . The method of  claim 10 , further comprising an air oxidation step. 
     
     
         18 . The method of  claim 10 , further comprising adding at most 5 wt. % by weight rare earth elements. 
     
     
         19 . The method of  claim 10 , further comprising adding at most 1 wt. % by weight rare earth elements. 
     
     
         20 . The method of  claim 10 , wherein said consolidation comprises one of: cold pressing-sintering, cold spray and spark plasma sintering.