Electrode for the electroplating or electrodeposition of a metal

Abstract

An electrode for electroplating or electrodeposition of a metal and to the method for obtaining the same is provided. The electrode has a conductive substrate, at least one layer of an electrochemically active coating placed on the substrate, and at least one topcoating layer of valve metal.

1 . An electrode suitable for the electroplating or electrodeposition of a metal from an electrolyte solution in an electrolytic cell comprising a conductive substrate, at least one topcoating layer of a first composition and at least one electrochemically active coating layer of a second composition different from the first one, the electrochemically active coating layer being positioned between the conductive substrate and the topcoating layer, the first composition containing 90-100% niobium or oxides thereof, wherein said topcoating layer is obtained via thermal decomposition of a precursor solution comprising an aqueous solution of niobium oxalate in acetic acid. 
     
     
         2 . The electrode according to  claim 1  wherein the first composition contains substantially 100% niobium or oxides thereof. 
     
     
         3 . The electrode according to  claim 1  wherein the first composition contains at least one doping agent selected from the group consisting of antimony, indium, molybdenum, tungsten, bismuth, tantalum and oxides thereof in an amount of 0.01-10% by weight. 
     
     
         4 . The electrode according to  claim 1  wherein the total amount of niobium in the topcoating layer is between 2-18 g/m 2 . 
     
     
         5 . The electrode according to  claim 1  wherein the second composition consists of 50-80% iridium and 20-50% tantalum, expressed in weight percentage. 
     
     
         6 . The electrode according to  claim 1  further comprising at least one underlayer containing a third composition different from the second composition, said underlayer being positioned between the conductive substrate and the electrochemically active coating layer, the third composition optionally comprising a mixture of tantalum and titanium oxides. 
     
     
         7 . The electrode according to  claim 1  wherein the conductive substrate is made of a valve metal selected from the group consisting of titanium, tantalum, zirconium, niobium, tungsten, aluminum, silicon, their alloys and intermetallic mixtures. 
     
     
         8 . A method for manufacturing the electrode according to  claim 1  comprising the formation of a topcoating over a conductive substrate, the conductive substrate being coated with an electrochemically active coating comprising at least one electrochemically active coating layer, the topcoating comprising at least one topcoating layer containing 90-100% niobium or oxides thereof, wherein the formation of said at least one topcoating layer comprises the sequential steps of:
 (i) applying a precursor solution over the conductive substrate coated with the at least one electrochemically active coating layer; 
 (ii) drying the precursor solution at a temperature of 50-100° C. for 5-20 minutes, optionally at a temperature of 50-70° C. for 7-15 minutes; 
 (iii) thermally decomposing the dried precursor solution at a temperature of 350-600° C. for 5-20 minutes, optionally at a temperature of 470-550° C. for 7-15 minutes; 
 
       the precursor solution comprising a Nb precursor solution obtained by diluting an aqueous solution of niobium oxalate in acetic acid. 
     
     
         9 . An unseparated electrolytic cell for the electroplating or electrodepositing of a metal from an electrolyte solution comprising at least one anode and at least one cathode at least partially immersed in the electrolyte solution, the electrolyte solution containing an organic substituent and said metal in solution; wherein said anode is the electrode according to  claim 1 . 
     
     
         10 . A process for the electroplating or electrodeposition of a metal from an electrolyte solution comprising carrying out electroplating or electrodeposition in the electrolytic cell according to claim  11  wherein the at least one anode in said cell is operated so that the consumption of said organic substituent is reduced while maintaining anode potential in said cell.