Electroplated coatings for hydraulic components

Abstract

An example hydraulic system component of a machine includes a protective coating deposited by electroplating in a multi-anodic plating tool. The plating tool allows for independent control of the anodic current, voltage, and/or waveform of each of the anodes to provide a uniform, hard, and dense protective coating along a length of an elongated component, such as a rod, cylinder, or piston. The electroplating process may allow for independent control of rectifiers providing power to the electrically isolated anodes to achieve a high level of uniformity over the length of the components being electroplated. The coating may include a layer of trivalent chromium electroplated over an electroplated layer of nickel to protect the component from wear, oxidation, and/or corrosion. The bi-layer coating may be relatively thin, with a thickness less than 125 microns.

What is claimed is: 
     
         1 . A hydraulic component, comprising:
 a steel surface; and   a coating disposed over the steel surface, wherein:
 the coating includes a first layer of nickel (Ni) provided directly on the steel surface, 
 the coating includes a second layer of trivalent chromium (Cr) provided directly on the first layer, 
 the coating has a thickness of less than 125 micrometers (μm), 
 the coating having a uniformity of 15 μm or less along its length, and 
 the coating is characterized by a hardness exceeding 800 Vickers Hardness (Hv). 
   
     
     
         2 . The hydraulic component of  claim 1 , wherein the hydraulic component comprises at least one of: (i) a rod, (ii) a cylinder, or (iii) a piston. 
     
     
         3 . The hydraulic component of  claim 1 , wherein the coating has a thickness less than 50 μm. 
     
     
         4 . The hydraulic component of  claim 1 , wherein the second layer is characterized by a hardness greater than 1300 Hv. 
     
     
         5 . The hydraulic component of  claim 1 , wherein the second layer has a thickness in a range of about 3 μm to about 50 μm. 
     
     
         6 . The hydraulic component of  claim 1 , wherein the hydraulic component has a length of greater than 6 feet and the coating has a uniformity within about 5 μm over the length of the hydraulic component. 
     
     
         7 . A plating tool, comprising:
 a reservoir configured to hold an electroplating bath;   an electroplating chamber fluidically coupled to the reservoir and configured to receive the electroplating bath from the reservoir;   a first annular anode disposed within the electroplating chamber;   a second annular anode disposed within the electroplating chamber and axially aligned with the first annular anode;   a first rectifier electrically coupled to the first annular anode and configured to provide a first current to the first annular anode; and   a second rectifier electrically coupled to the second annular anode and configured to provide a second current to the second annular anode.   
     
     
         8 . The plating tool of  claim 7 , wherein the first current is different from the second current. 
     
     
         9 . The plating tool of  claim 7 , further comprising:
 a spacer electrically isolating the first annular anode from the second annular anode.   
     
     
         10 . The plating tool of  claim 7 , wherein the electroplating chamber includes high density polyethylene (HDPE). 
     
     
         11 . The plating tool of  claim 7 , wherein the first annular anode includes at least one of: (i) graphite, (ii) titanium (Ti), (iii) a mixed metal oxide, or (iv) platinum (Pt) coated Ti. 
     
     
         12 . The plating tool of  claim 7 , further comprising:
 a controller to control the first rectifier to provide the first current.   
     
     
         13 . The plating tool of  claim 7 , further comprising:
 a third annular anode disposed within the electroplating chamber and axially aligned with the first annular anode; and   a third rectifier electrically coupled to the third annular anode and configured to provide a third current to the third annular anode.   
     
     
         14 . A method, comprising:
 providing an electroplating bath in an electroplating chamber;   providing a first annular anode immersed in the electroplating bath;   providing a second annular anode immersed in the electroplating bath such that the first annular anode and the second annular anode are substantially axially aligned;   immersing a component into the electroplating bath such that the first annular anode conformally surrounds a first part of the component and the second annular anode conformally surrounds a second part of the component;   providing first power from a first rectifier electrically coupled to the first annular anode to electroplate a first coating substantially onto the first part of the component; and   providing second power from a second rectifier electrically coupled to the second annular anode to electroplate a second coating substantially onto the second part of the component, wherein the first rectifier and the second rectifier are electrically isolated.   
     
     
         15 . The method of  claim 14 , further comprising:
 determining, based at least in part on a length of the component, that the first rectifier and the second rectifier are to be energized.   
     
     
         16 . The method of  claim 14 , further comprising:
 forming the component from steel; and   hardening the component.   
     
     
         17 . The method of  claim 14 , wherein the component is a preexisting component that is to be remanufactured by deposition of a protective coating. 
     
     
         18 . The method of  claim 14 , the electroplating bath is a nickel electroplating bath and the method further comprising:
 electroplating a first layer of nickel on the component; and   electroplating a second layer of chromium over the first layer of nickel.   
     
     
         19 . The method of  claim 18 , further comprising:
 rinsing the component after electroplating the second layer of chromium.   
     
     
         20 . The method of  claim 14 , further comprising:
 providing a third annular anode immersed in the electroplating bath such that the first annular anode and the third annular anode are substantially axially aligned; and   providing third power from a third rectifier electrically coupled to the third annular anode to electroplate a third coating substantially onto a third part of the component, wherein the second rectifier and the third rectifier are electrically isolated.