Nickel-Chromium Nanolaminate Coating Having High Hardness

Abstract

The present disclosure describes electrodeposited nanolaminate materials having layers comprised of nickel and/or chromium with high hardness. The uniform appearance, chemical resistance, and high hardness of the nanolaminate NiCr materials described herein render them useful for a variety of purposes including wear (abrasion) resistant barrier coatings for use both in decorative as well as demanding physical, structural and chemical environments.

1 . A process for forming a multilayered nickel and chromium containing coating on a surface of a substrate or mandrel by electrodeposition comprising:
 (a) providing one or more electrolyte solutions comprising a nickel salt and/or a chromium salt;   (b) providing a conductive substrate or mandrel for electrodeposition;   (c) contacting at least a portion of the surface of the substrate or mandrel with one of said one or more electrolyte solutions;   (d) passing a first electric current through the substrate or mandrel, to deposit a first layer comprising either nickel or an alloy thereof, on the substrate or mandrel; and passing a second electric current through the substrate, to deposit a second layer comprising a nickel-chromium alloy on the surface;   (e) repeating step (d) two or more times thereby producing a multilayered coating having first layers of nickel, or an alloy thereof, and second layers of a nickel-chromium alloy on at least a portion of the surface of the substrate or mandrel; and   optionally separating the substrate or mandrel from the coating.   
     
     
         2 . The process of  claim 1 , wherein:
 said providing one or more electrolyte solutions comprises providing an electrolyte solution comprising a nickel salt and a chromium salt;   passing an electric current through said substrate or mandrel comprises alternately pulsing said electric current for predetermined durations between said first electrical current and said second electrical current;   where said first electrical current is effective to electrodeposit a first composition comprising nickel or an alloy of nickel and chromium; and   where said second electrical current is effective to electrodeposit a second composition comprising nickel and chromium; thereby producing a multilayered alloy having alternating first and second layers, said first layer comprising either nickel or an alloy thereof, and said second layer comprising a nickel-chromium alloy on at least a portion of the surface of the substrate or mandrel.   
     
     
         3 . The process of  claim 1 , wherein at least one of said one or more electrolyte solutions is an aqueous solution comprising one or more complexing agents. 
     
     
         4 . The process of  claim 3 , wherein said complexing agent is selected from one or more, two or more or three or more of citric acid, EDTA, triethanolamine (TEA), ethylenediamine (En), formic acid, acetic acid, hydroxyacetic acid, malonic acid, or an alkali metal or ammonium salt of any thereof. 
     
     
         5 . (canceled) 
     
     
         6 . The process of  claim 1 , wherein the first electric current ranges from approximately 10 mA/cm 2  to approximately 100 mA/cm 2 , and wherein the second electric current ranges from approximately 100 mA/cm 2  to approximately 500 mA/cm 2 . 
     
     
         7 - 13 . (canceled) 
     
     
         14 . The process of  claim 1 , wherein said first layer comprises greater than about 92% nickel by weight and a balance of other elements. 
     
     
         15 . The process of  claim 1 , wherein said second layer comprises about 10% to about 21%, chromium by weight and a balance of other elements. 
     
     
         16 - 17 . (canceled) 
     
     
         18 . The process of  claim 1 , wherein the first layer and/or the second layer comprises one to four or more elements selected independently for each layer from the group consisting of C, Co, Cu, Fe, In, Mn, Nb, W, Mo, and P. 
     
     
         19 . (canceled) 
     
     
         20 . The process of  claim 1 , comprising fifty or more alternating first layers and second layers. 
     
     
         21 . An object or coating comprising a coating prepared by the method of  claim 1 . 
     
     
         22 . An object or coating comprising a multilayered coating comprising a plurality of alternating first layers of nickel, or an alloy comprising nickel, and second layers of an alloy comprising nickel and chromium, and optionally comprising a substrate. 
     
     
         23 - 27 . (canceled) 
     
     
         28 . The object or coating of any of  claim 22 , wherein each first layer comprises greater than about 92% nickel, and wherein each second layer comprises chromium in a range independently selected from 10%-21% chromium. 
     
     
         29 - 34 . (canceled) 
     
     
         35 . The object or coating of  claim 22 , wherein said first layers consist of nickel or a nickel chromium alloy and said second layers consist of a nickel-chromium alloy and wherein said coating has a Vickers microhardness as measured by ASTM E384-11e1 of 550-750, 750-800, or 800-850 without heat treatment. 
     
     
         36 . (canceled) 
     
     
         37 . The object or coating of  claim 22 , wherein said substrate comprises one or more elements selected from the group consisting of C, Co, Cu, Fe, In, Mn, Nb, W, Mo, and P. 
     
     
         38 - 39 . (canceled) 
     
     
         40 . The object or coating of  claim 22 , wherein said object resists corrosion of said substrate caused by exposure to one or more of water, air, acid, base, salt water and/or H 2 S. 
     
     
         41 . The object or coating of  claim 37 , wherein said first layers consist of nickel, or a nickel chromium alloy, and said second layers consist of a nickel-chromium alloy, and wherein said coating has a Vickers microhardness as measured by ASTM E384-11e1 of 550-750, 750-800, or 800-850 without heat treatment. 
     
     
         42 . (canceled)