Electrodeposited zinc and iron coatings for corrosion resistance

Abstract

Electrolyte solutions for electrodeposition of zinc alloys and methods of electrodepositing zinc-iron alloys. An electrolyte solution for electroplating can include an alkali metal hydroxide, a zinc salt, a condensation polymer of epichlorohydrin, a quaternary amine, an aliphatic amine, a polyhydroxy alcohol, an aromatic organic acid and/or salts thereof, an amino alcohol, a bisphosphonic acid and/or salts thereof, an iron salt, an alkali metal gluconate, and an amine-based chelating agent. Electrodepositing zinc alloys on a substrate can include introducing a cathode and an anode into an electrolyte solution comprising an alkali metal hydroxide, a zinc salt, a condensation polymer of epichlorohydrin, a quaternary amine, an aliphatic amine, a polyhydroxy alcohol, an aromatic organic acid and/or salts thereof, an amino alcohol, a bisphosphonic acid and/or salts thereof, an iron salt, an alkali metal gluconate, and an amine-based chelating agent.

What is claimed is: 
     
         1 . A substrate comprising:
 a zinc-iron alloy coating having a zinc content in a range of about 75 wt. % to about 95 wt. % and an iron content in a range of about 5 wt. % to about 25 wt. %.   
     
     
         2 . The substrate of  claim 1 , wherein the substrate comprises one or more of steel, copper, brass, or nickel. 
     
     
         3 . The substrate of  claim 1 , wherein the zinc-iron alloy coating has a thickness of from about 1 micron and about 300 microns. 
     
     
         4 . The substrate of  claim 3 , wherein the zinc-iron alloy coating has a thickness of from about 1 micron and about 30 microns. 
     
     
         5 . The substrate of  claim 2 , wherein the zinc-iron alloy coating has a thickness of from about 10 microns and about 20 microns. 
     
     
         6 . The substrate of  claim 2 , wherein the substrate comprises steel. 
     
     
         7 . The substrate of  claim 6 , wherein the zinc-iron alloy coating provides corrosion protection 
     
     
         8 . The substrate of  claim 1 , wherein the zinc-iron alloy coating comprises an iron content of about 10 wt. % to about 25 wt. %. 
     
     
         9 . The substrate of  claim 1 , wherein the zinc-iron alloy coating comprises an iron content of about 10 wt. % to about 20 wt. %. 
     
     
         10 . The substrate of  claim 1 , wherein the zinc-iron alloy coating comprises a zinc content of about 80 wt. % to about 90 wt. %. 
     
     
         11 . An electrolyte solution for electroplating comprising:
 an alkali hydroxide;   a zinc salt;   a condensation polymer of epichlorohydrin;   a quaternary amine;   an aliphatic amine;   a polyhydroxy alcohol;   an aromatic organic acid and/or salts thereof;   an amino alcohol;   a bisphosphonic acid and/or salts thereof;   an iron salt;   an alkali metal gluconate; and   an amine-based chelating agent.   
     
     
         12 . The electrolyte solution of  claim 11 , wherein:
 the alkali hydroxide is present in an amount ranging from about 1.0 mole per liter (mol/L) to about 5 mol/L of the electrolyte solution;   the zinc salt is present in an amount ranging from about 0.1 moles per liter to about 0.2 moles per liter of the electrolyte solution;   the condensation polymer of epichlorohydrin is present in an amount ranging from about 10 grams/liter to about 25 grams/liter of the electrolyte solution;   the quaternary amine is present in an amount ranging from about 10 grams/L to about 30 grams/L;   the aliphatic amine is present in an amount ranging from about 0.03 moles per liter to about 0.05 moles per liter;   the polyhydroxy alcohol is present in an amount ranging from about 0.03 moles per liter to about 0.06 moles per liter;   the aromatic organic acid and/or salts thereof is present in an amount ranging from about 0.002 moles per liter to about 0.008 moles per liter;   the amino alcohol is present in an amount ranging from about 0.1 moles per liter to about 0.4 moles per liter;   the a bisphosphonic acid or salts thereof is present in an amount ranging from about 0.01 moles per liter to about 0.02 moles per liter;   the iron salt is present in an amount ranging from about 0.05 moles per liter to about 0.1 moles per liter;   the alkali metal gluconate is present in an amount ranging from about 0.05 moles per liter to about 0.12 moles per liter; and   the amine-based chelating agent is present in an amount ranging from about 7 grams/liter to about 15 grams/liter.   
     
     
         13 . The electrolyte solution of  claim 11 , wherein the zinc salt is zinc oxide or a divalent zinc salt. 
     
     
         14 . The electrolyte solution of  claim 11 , wherein the condensation polymer of epichlorohydrin is an imidazole-epichlorohydrin condensation polymer, an amine-formaldehyde-epichlorohydrin condensation polymer, or a combination thereof. 
     
     
         15 . The electrolyte solution of  claim 11 , wherein the aliphatic amine is selected from ethylenediamine, diethylenetriamine, dipropylaminetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenediamine, and N,N′-bis-(triaminopropyl) ethylenediamine, or a combination thereof. 
     
     
         16 . The electrolyte solution of  claim 11 , wherein the aromatic organic acid and/or salts thereof is selected from sodium benzoate, potassium benzoate, or a combination thereof. 
     
     
         17 . The electrolyte solution of  claim 11 , wherein the amino alcohol is selected from ethanolamine, diethanolamine, triethanolamine, or a combination thereof. 
     
     
         18 . The electrolyte solution of  claim 11 , wherein the iron salt is a divalent iron salt comprising one or more of iron (II) sulfate, iron (II) chloride, iron (II) acetate, and hydrates thereof. 
     
     
         19 . The electrolyte solution of  claim 11 , wherein the alkali metal gluconate is selected from sodium gluconate, potassium gluconate, or a combination thereof. 
     
     
         20 . The electrolyte solution of  claim 11 , wherein the electrolyte solution has a pH of about 14.