Composition for making wettable cathode in aluminum smelting

Abstract

Compositions for making wettable cathodes to be used in aluminum electrolysis cells are disclosed. The compositions generally include titanium diboride (TiB 2 ) 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.

1 . An electrode for use in an aluminum electrolysis cell, the electrode comprising:
 0.01 to 0.75 wt. % metal additives, wherein the metal additives are selected from the group consisting of Fe, Ni, Co, and W, and combinations thereof;   the balance being TiB 2  and unavoidable impurities, wherein the unavoidable impurities make up less than 2 wt. % of the electrode;   wherein the electrode has a density of at least about 85% of its theoretical density.   
     
     
         2 . The electrode of  claim 1 , wherein the electrode includes not greater than 0.65 wt. % metal additives. 
     
     
         3 . The electrode of  claim 1 , wherein the electrode includes not greater than 0.50 wt. % metal additives. 
     
     
         4 . The electrode of  claim 3 , wherein the electrode includes at least about 0.05 wt. % metal additives. 
     
     
         5 . The electrode of  claim 4 , wherein the metal additive is selected from the group consisting of Fe, Ni and Co. 
     
     
         6 . The electrode of  claim 5 , wherein the metal additive is Fe. 
     
     
         7 . The electrode of  claim 5 , wherein the metal additive is Ni. 
     
     
         8 . The electrode of  claim 5 , wherein the metal additive is Co. 
     
     
         9 . The electrode of  claim 1 , comprising:
 0.01 to 0.14 wt. % Fe;   0.01 to 0.14 wt. % Ni;   0.01 to 0.14 wt. % Co; and   0.01 to 0.45 wt. % W.   
     
     
         10 . The electrode of  claim 9 , comprising not greater than 0.10 wt. % each of Fe, Ni, and Co. 
     
     
         11 . The electrode of  claim 9 , comprising not greater than 0.07 wt. % each of Fe, Ni, and Co. 
     
     
         12 . The electrode of  claim 9 , comprising not greater than 0.05 wt. % each of Fe, Ni, and Co. 
     
     
         13 . The electrode of  claim 10 , comprising not greater than 0.30 wt. % W. 
     
     
         14 . The electrode of  claims 12 , comprising not greater than 0.20 wt. % W. 
     
     
         15 . An aluminum electrolysis cell comprising the electrode of  claim 1 . 
     
     
         16 . A method comprising:
 (a) producing a blended TiB 2  composition, the producing step comprising:
 (i) selecting a metal additive selected from the group consisting of Fe, Ni, and Co, and combinations thereof; 
 (ii) selecting a density of an electrode to be produced; 
 (iii) selecting an amount of the metal additive to achieve the selected density; and 
 (iv) blending the selected amount of metal additive with a TiB 2  powder to produce a blended powder composition; 
   (b) producing an electrode from the blended TiB 2  composition, wherein the electrode realizes an actual density that is substantially similar to the selected density.   
     
     
         17 . The method of  claim 16 , wherein the selected density is in the range of from about 4.068 g/cc to about 4.430 g/cc, and wherein the amount of selected metal additive is in the range of 0.01 to 0.75 wt. %. 
     
     
         18 . The method of  claim 16 , comprising:
 using the electrode as one of a cathode and an anode in an aluminum electrolysis cell, wherein the using comprises:   passing electricity through the electrode while the electrode is in communication with a molten salt bath of the aluminum electrolysis cell; and   in response to the passing step, reducing Al 2 O 3  of the molten salt bath to aluminum metal.   
     
     
         19 . The method of  claim 18 , wherein, during the using step, the electrode remains whole and absent of delamination and cracking for at least 120 days of continuous use. 
     
     
         20 . A composition consisting essentially of TiB 2  and metal additives, wherein the composition includes 0.01 to 0.75 wt. % metal additives, the balance being the TiB 2  and unavoidable impurities, wherein the unavoidable impurities make up less than 2 wt. % of the electrode;
 wherein the metal additives are selected from the group consisting of Fe, Ni, Co, and W, and combinations thereof; and   wherein the electrode has a density of from about 85% to about 99% of its theoretical density.