# US 10,767,274 B2 · Compositionally modulated zinc-iron multilayered coatings

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- Number: US 10,767,274 B2
- Document ID: US10767274B2
- Status: Granted
- Kind: B2
- Application number: 15/680,326
- Filed: 2017-08-18
- Published: 2018-12-13
- Granted: 2020-09-08
- Earliest claimed: 2017-06-09
- Assignees: The Boeing Company
- Applicants: The Boeing Company
- Inventors: Stephen P. Gaydos; Vijaykumar S. Ijeri; Om Prakash; Trilochan Mishra; Raghuvir Singh; Shashi Kant Tiwari
- Web page: https://patentgrep.com/patent/US10767274B2

## CPC

- C25D 3/562: {containing more than 50% by weight of iron or nickel or cobalt}
- C25D 3/24: from cyanide baths
- C25D 3/54: of metals not provided for in groups C25D3/04 - C25D3/50
- C25D 3/565: {containing more than 50% by weight of zinc}
- C25D 5/10: Electroplating with more than one layer of the same or of different metals (for bearings C25D7/10)
- C25D 5/12: at least one layer being of nickel or chromium
- C25D 5/18: Electroplating using modulated, pulsed or reversing current
- C25D 5/623: {Porosity of the layers}
- C25D 5/627: {Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance}
- Y02P 10/25: Process efficiency
- C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

The present disclosure provides electrolyte solutions for electrodeposition of zinc-iron alloys, methods of forming electrolyte solutions, and methods of electrodepositing zinc-iron alloys. An electrolyte solution for electroplating can include an alkali metal citrate, an alkali metal acetate, a citric acid, and glycine with a metal salt. An electrolyte solution can be formed by dissolving an alkali metal citrate, an alkali metal acetate, a citric acid, and glycine in water or an aqueous solution. Electrodepositing zinc-iron alloys on a substrate can include introducing a cathode and an anode into an electrolyte solution comprising an alkali metal citrate, an alkali metal acetate, a citric acid, and glycine. Electrodepositing can further include passing a current between the cathode and the anode through the electrolyte solution to deposit zinc and iron onto the cathode.

## Claims

### Claim 1

A method for electrodepositing a zinc-iron alloy on a substrate, the method comprising:
introducing a cathode and an anode into an electrolyte solution comprising a zinc salt, an iron salt, an alkali metal citrate, an alkali metal acetate, a citric acid, and glycine, the electrolyte solution having a glycine concentration from about 0.1 moles per liter (mol/L) to about 2 mol/L and an alkali metal citrate concentration from about 0.001 mol/L to about 0.1 mol/L; and
passing a first current between the cathode and the anode through the electrolyte solution to deposit a first layer containing zinc and iron onto the cathode, the first current having a first current density from about 1 mA/cm2 to about 500 mA/cm2.

### Claim 2 (depends on 1)

The method of claim 1, wherein the electrolyte solution further comprises thiamine hydrochloride.

### Claim 3 (depends on 2)

The method of claim 2, wherein the electrolyte solution comprises a concentration of the thiamine hydrochloride from about 0.0001 moles per liter (mol/L) to about 1 mol/L.

### Claim 4 (depends on 3)

The method of claim 3, wherein a concentration of the thiamine hydrochloride in the electrolyte solution is about 0.0015 mol/L.

### Claim 5 (depends on 1)

The method of claim 1, 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.

### Claim 6 (depends on 1)

The method of claim 1, wherein the anode is a zinc material, platinum material, platinized titanium material, or a carbonaceous electrode material.

### Claim 7 (depends on 1)

The method of claim 1, wherein the first current has a first current density from about 5 mA/cm2 to about 200 mA/cm2.

### Claim 8 (depends on 7)

The method of claim 7, wherein the first current includes a pulsed current formed from a series of pulses and each pulse has a duration of from about 20 milliseconds to about 800 milliseconds.

### Claim 9 (depends on 8)

The method of claim 8, wherein a temperature of the electrolyte solution is maintained at a temperature from about 20° C. to about 35° C. while passing the first current.

### Claim 10 (depends on 1)

The method of claim 1, further comprising passing a second current between the cathode and the anode to deposit a second layer comprising zinc and iron onto the first layer, the second current having a second current density from about 5 mA/cm2 to about 500 mA/cm2, the second current density being different than the first current density.

### Claim 11 (depends on 10)

The method of claim 10, further comprising repeating passing the first current and the second current between the cathode and the anode to form a coating having a plurality of alternating layers, wherein the plurality of alternating layers have substantially the same thickness and two or more of the layers have a different iron content.

### Claim 12 (depends on 10)

The method of claim 10, further comprising repeating passing the first current and the second current between the cathode and the anode to form a coating having a plurality of alternating layers, wherein two or more of the plurality of alternating layers have a different thickness and two or more of the plurality of alternating layers have a different iron content.

### Claim 13 (depends on 10)

The method of claim 10, further comprising repeating passing the first current and the second current between the cathode and the anode to form a coating having a plurality of alternating layers comprising:
the first layer having a first iron content,
the second layer having a second iron content different than the first iron content,
a third layer having the same iron content as the first layer, and
a fourth layer having the same iron content as the second layer.

### Claim 14 (depends on 10)

The method of claim 10, further comprising repeating passing the first current and the second current between the cathode and the anode to form a coating having a plurality of alternating layers, wherein each layer has substantially the same thickness and each layer has a different iron content.

### Claim 15 (depends on 10)

The method of claim 10, further comprising repeating passing the first current and the second current between the cathode and the anode to form a coating having a plurality of alternating layers, wherein each layer has a different thickness and each layer has a different iron content.

### Claim 16 (depends on 1)

The method of claim 1, further comprising passing a second current between the cathode and the anode having the same current density as the first current density of the first current to deposit a second layer comprising zinc and iron onto the first layer deposited by the first current.

### Claim 17 (depends on 16)

The method of claim 16, further comprising repeating passing the first current and the second current between the cathode and the anode to form a coating having a plurality of alternating layers having an iron content, wherein each of the first current and the second current substantially the same duration and the plurality of alternating layers have substantially the same thickness and substantially the same iron content.

### Claim 18 (depends on 1)

The method of claim 1, wherein first layer comprises an iron content from about 8.9 wt. % to about 62.4 wt. %.

### Claim 19 (depends on 1)

The method of claim 1, wherein a concentration of the alkali metal citrate in the electrolyte solution is about 0.018 mol/L.

### Claim 20 (depends on 1)

The method of claim 1, wherein a concentration of the glycine in the electrolyte solution is about 0.146 mol/L.

### Claim 21

A method for electrodepositing a zinc-iron alloy on a substrate, the method comprising:
introducing a cathode and an anode into an electrolyte solution comprising a zinc salt, an iron salt, an alkali metal citrate, an alkali metal acetate, a citric acid, thiamine hydrochloride, and glycine, the electrolyte solution having a thiamine hydrochloride concentration from about 0.0001 moles per liter (mol/L) to about 1 mol/L an alkali metal citrate concentration from about 0.001 mol/L to about 0.1 mol/L, have been inserted after the concentration “1 mol/L”, and a glycine concentration from about 0.1 mol/L to about 2 mol/L;
passing a first current having a first current density between the cathode and the anode through the electrolyte solution to deposit a first layer containing zinc and iron onto the cathode to form a zinc-iron alloy on a substrate, the first layer comprising an iron content from about 8.9 wt. % to about 62.4 wt. %; and
passing a second current between the cathode and the anode to deposit a second layer comprising zinc and iron onto the first layer, the second current having a second current density, wherein each of the first current density and the second current density is from about 1 mA/cm2 to about 500 mA/cm2, the first current density being different than the second current density.

### Claim 22 (depends on 21)

The method of claim 21, wherein a concentration of the thiamine hydrochloride in the electrolyte solution is about 0.0015 mol/L.

### Claim 23 (depends on 21)

The method of claim 21, wherein a concentration of the glycine in the electrolyte solution is about 0.146 mol/L.

### Claim 24

A method for electrodepositing a zinc-iron alloy on a substrate, the method comprising:
introducing a cathode and an anode into an electrolyte solution comprising a zinc salt, an iron salt, an alkali metal citrate, an alkali metal acetate, a citric acid, and glycine, the electrolyte solution having a glycine concentration from about 0.1 mol/L to about 2 mol/L and an alkali metal citrate concentration from about 0.001 mol/L to about 0.1 mol/L have been inserted after the concentration “mol/L”;
passing a first current having a first current density between the cathode and the anode through the electrolyte solution to deposit a first layer containing zinc and iron onto the cathode to form a zinc-iron alloy on a substrate,
passing a second current between the cathode and the anode to deposit a second layer comprising zinc and iron onto the first layer, each of the first current and the second current having a second current density from about 1 mA/cm2 to about 500 mA/cm2, the first current density being less than the second current density; and
repeating passing the first current and the second current between the cathode and the anode to form a coating having a plurality of alternating layers including the first layer and the second layer, the first layer comprising a first iron content from about 8.9 wt. % to about 62.4 wt. %, wherein the first iron content is less than a second iron content of the second layer.

### Claim 25 (depends on 24)

The method of claim 24, wherein a concentration of the glycine in the electrolyte solution is about 0.146 mol/L.

### Claim 26 (depends on 24)

The method of claim 24, wherein the electrolyte solution further comprises thiamine hydrochloride.

### Claim 27 (depends on 26)

The method of claim 26, wherein the electrolyte solution comprises a concentration of the thiamine hydrochloride is from about 0.0001 moles per liter (mol/L) to about 1 mol/L.

### Claim 28 (depends on 24)

The method of claim 24, wherein a thickness of the first layer is from about 0.1 microns to about 5 microns.

### Claim 29 (depends on 24)

The method of claim 24, wherein a thickness of the coating is from about 1 micron to about 100 microns.