Method of forming a porous nickel coating, and related articles and compositions

Abstract

A method of forming a porous nickel coating is provided. The method includes the steps of: depositing a coating onto a substrate by melting and atomizing two consumable electrode wires of a selected composition in a wire-arc spray device, so as to form a molten, atomized material, and directing the material to the substrate to form a coating deposit; the selected composition including nickel and a sacrificial metal; and then dissolving at least a portion of the sacrificial metal from the coating deposit by applying a positive potential in an alkaline electrolyte, so as to obtain a porous nickel coating. An electrolytic cell that includes a porous nickel coating is also described.

1 . A method of forming a porous nickel coating, comprising the steps of:
 depositing a coating onto a substrate by melting and atomizing two consumable electrode wires of a selected composition in a wire-arc spray device, so as to form a molten, atomized material, and directing the material to the substrate to form a coating deposit;   wherein the selected composition comprises nickel and zinc; and then   dissolving at least a portion of the zinc from the coating deposit by applying a positive potential in an alkaline electrolyte, so as to obtain a porous nickel coating.   
   
   
       2 . The method according to  claim 1 , wherein the total, selected composition of the consumable electrode wires comprises at least about 50 weight percent of zinc. 
   
   
       3 . The method according to  claim 1 , wherein a first consumable electrode wire comprises zinc. 
   
   
       4 . The method according to  claim 3 , wherein the first consumable electrode wire comprises at least about 90 weight percent of zinc, based on the total weight of the wire. 
   
   
       5 . The method according to  claim 1 , wherein a second consumable electrode wire comprises nickel. 
   
   
       6 . The method according to  claim 5 , wherein the second consumable electrode wire comprises at least one alloying additive selected from the group consisting of Al, Mo, Co, and combinations thereof. 
   
   
       7 . The method according to  claim 6 , wherein the amount of the alloying additive for the second consumable electrode wire is no greater than about 30%, based on the total weight of the wire. 
   
   
       8 . The method according to  claim 7 , wherein the second consumable electrode wire comprises the alloying additive in the range from about 0.05 weight percent to about 30 weight percent, based on the total weight of the wire. 
   
   
       9 . The method according to  claim 1 , wherein at least one of the consumable electrode wires comprises a powder-filled core and a solid metal shell. 
   
   
       10 . The method of  claim 1 , wherein dissolving at least a portion of the zinc comprises dissolving an amount of zinc in the range from about 70 weight percent to about 100 weight percent of zinc. 
   
   
       11 . The method of  claim 1 , wherein the positive potential is at least about 1.2 V vs. standard hydrogen electrode (SHE). 
   
   
       12 . The method of  claim 11 , wherein the positive potential is at least about 1.5 V vs. standard hydrogen electrode (SHE). 
   
   
       13 . The method of  claim 1 , wherein dissolving at least a portion of the zinc further comprises chemical leaching of the coating deposit prior to applying the positive potential. 
   
   
       14 . A porous nickel coating formed by the process of:
 depositing a coating onto a substrate by melting and atomizing two consumable electrode wires of a selected composition in a wire-arc spray device, so as to form a molten, atomized material, and directing the material to the substrate to form a coating deposit;   wherein the selected composition comprises nickel and zinc; and then   dissolving at least a portion of the zinc from the coating deposit by applying a positive potential in an alkaline electrolyte, so as to obtain a porous nickel coating.   
   
   
       15 . An electrolytic cell comprising at least one electrode which itself comprises the porous nickel coating obtained by the method of  claim 1 . 
   
   
       16 . A direct methanol fuel cell comprising at least one electrode which itself comprises the porous nickel coating obtained by the method of  claim 1 . 
   
   
       17 . A method of generating hydrogen from a cathode in an electrolytic cell by passing an electric current between an anode and the cathode, wherein the cathode comprises a porous nickel coating formed by:
 depositing coating onto a substrate by melting and atomizing two consumable electrode wires of a selected composition in a wire-arc spray device, so as to form a molten, atomized material, and directing the material to the substrate to form a coating deposit;   wherein the selected composition comprises nickel and zinc; and then   dissolving at least a portion of the zinc from the coating deposit by applying a positive potential in an alkaline electrolyte, so as to obtain a porous nickel coating.   
   
   
       18 . The method according to  claim 17 , wherein at least one of the consumable electrode wires comprises at least about 40 weight percent of zinc. 
   
   
       19 . The method according to  claim 18 , wherein at least one of the consumable electrode wires comprises at least about 80 weight percent of zinc. 
   
   
       20 . An electrochemical process using the electrolytic cell of  claim 15 , wherein the electrochemical process comprises at least one process selected from the group consisting of a chlor-alkali process, potassium permanganate production, potassium perchlorate production, potassium bichromate production, and oxidation of organic compounds. 
   
   
       21 . A method of making a porous nickel catalyst, comprising the steps of:
 depositing a coating onto a substrate by melting and atomizing two consumable electrode wires of a selected composition in a wire-arc spray device, so as to form a molten, atomized material, and directing the material to the substrate to form a coating deposit;   wherein the selected composition comprises nickel and zinc; and then dissolving at least a portion of the zinc from the coating deposit by applying a positive potential in an alkaline electrolyte, so as to obtain a porous nickel catalyst.   
   
   
       22 . A chemical process of hydrogenation of unsaturated chemical bonds, in which the porous nickel catalyst formed in  claim 21  is used to catalyze at least one step of the process. 
   
   
       23 . The chemical process of  claim 22 , wherein the porous nickel catalyst reduces a carbon-carbon double bond. 
   
   
       24 . A chemical process in which the porous nickel catalyst made in  claim 21  is used as a reagent. 
   
   
       25 . A method of forming a porous nickel coating, comprising the steps of:
 depositing a coating onto a substrate by melting and atomizing a first consumable electrode wire comprising nickel and at least one alloying additive selected from the group consisting of Al, Mo, Co, and a second consumable wire comprising zinc in a wire-arc spray device, so as to form a molten, atomized material, and directing the material to the substrate to form a coating deposit; and then   dissolving at least a portion of the zinc from the coating deposit by applying a positive potential in an alkaline electrolyte, so as to obtain a porous nickel coating.