Functional chromium alloy plating from trivalent chromium electrolytes

Abstract

The present disclosure provides electrolyte solutions for electrodeposition of chromium-iron alloys and methods of electrodepositing chromium-iron alloys. An electrolyte solution for electroplating can include a trivalent chromium salt, an oxalate compound, an iron salt, an aluminum sulfate, an alkali metal sulfate, and an alkali metal halide. An electrolyte solution can be formed by dissolving a trivalent chromium salt, an oxalate compound, an iron salt, an aluminum sulfate, an alkali metal sulfate, and an alkali metal halide in water or an aqueous solution. Electrodepositing chromium-iron alloys on a substrate can include introducing a cathode and an anode into an electrolyte solution comprising a trivalent chromium salt, an oxalate compound, an iron salt, an aluminum sulfate, an alkali metal sulfate, and an alkali metal halide. Electrodepositing can further include passing a current between the cathode and the anode through the electrolyte solution to deposit chromium and iron onto the cathode.

What is claimed is: 
     
         1 . An electrolyte solution for electroplating comprising:
 a trivalent chromium salt;   an oxalate compound;   an iron salt;   an aluminum sulfate;   an alkali metal sulfate; and   an alkali metal halide.   
     
     
         2 . The electrolyte solution of  claim 1 , wherein:
 the trivalent chromium salt is present in an amount ranging from about 0.3 moles per liter to about 0.9 moles per liter of the electrolyte solution;   the oxalate compound is present in an amount ranging from about 0.2 moles per liter to about 1.2 moles per liter of the electrolyte solution;   the iron salt is present in an amount ranging from about 0.005 moles per liter to about 0.2 moles per liter of the electrolyte solution;   the aluminum sulfate is present in an amount ranging from about 0.05 moles per liter to about 0.5 moles per liter;   the alkali metal sulfate is present in an amount ranging from about 0.1 moles per liter to about 2.0 moles per liter of the electrolyte solution; and   the alkali metal halide is present in an amount ranging from about 0.1 moles per liter to about 0.5 moles per liter of the electrolyte solution.   
     
     
         3 . The electrolyte solution of  claim 1 , 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. 
     
     
         4 . The electrolyte solution of  claim 1 , wherein the iron salt is a trivalent iron salt comprising one or more of iron (III) sulfate, iron (III) chloride, iron (III) acetate, and hydrates thereof. 
     
     
         5 . The electrolyte solution of  claim 1 , wherein the trivalent chromium salt is selected from a chromium (III) halide, a chromium (III) sulfate, or a combination thereof. 
     
     
         6 . The electrolyte solution of  claim 1 , wherein the oxalate compound is selected from sodium oxalate, potassium oxalate, an acid of oxalate, or a combination thereof. 
     
     
         7 . The electrolyte solution of  claim 1 , wherein the alkali metal sulfate is selected from sodium sulfate, potassium sulfate, or a combination thereof. 
     
     
         8 . The electrolyte solution of  claim 1 , wherein the alkali metal halide is selected from sodium fluoride, potassium fluoride, or a combination thereof. 
     
     
         9 . The electrolyte solution of  claim 1 , wherein a pH of the electrolyte solution is in a range from about 1 to about 4. 
     
     
         10 . The electrolyte solution of  claim 1 , further comprising sodium lauryl sulfate, sodium lauryl ether sulfate, or a combination thereof. 
     
     
         11 . A method of chrome plating on a substrate using an electrolyte solution, comprising:
 introducing a cathode and an anode into an electrolyte solution comprising a trivalent chromium salt, an oxalate compound, an iron salt, an aluminum sulfate, an alkali metal sulfate, and an alkali metal halide; and   passing a current between the anode and the cathode through the electrolyte solution to deposit a chromium layer on the substrate.   
     
     
         12 . The method of  claim 11 , wherein the cathode is a steel substrate, a copper substrate, a brass substrate, a nickel substrate, a copper-coated substrate, or a nickel-coated substrate. 
     
     
         13 . The method of  claim 11 , wherein the anode is a platinum material, platinized titanium material, or a carbonaceous electrode material. 
     
     
         14 . The method of  claim 11 , wherein the current has a current density in a range from about 10 to about 60 mA/cm 2  by passing direct current between the anode and the cathode. 
     
     
         15 . The method of  claim 14 , wherein the current density has a current density in a range from about 20 to about 40 mA/cm 2 . 
     
     
         16 . The method of  claim 14 , wherein the electrolyte solution is maintained at a temperature in a range from about 20 degrees Celsius and about 60 degrees Celsius. 
     
     
         17 . The method of  claim 11 , further comprising adjusting a pH of the electrolyte solution to a pH in a range from about 1.5 to about 4. 
     
     
         18 . A substrate comprising:
 a chromium-iron alloy coating having a chromium content in a range of about 40 wt. % to about 90 wt. %, an iron content in a range of about 8 wt. % to about 18 wt. %, and a carbon content in a range of about 5 wt. % to about 50 wt. %.   
     
     
         19 . The substrate of  claim 18 , wherein the substrate comprises one or more of steel, copper, brass, or nickel. 
     
     
         20 . The substrate of  claim 19 , wherein the chromium-iron alloy coating has a thickness of from about 1 micron and about 100 microns.