Coatings containing nickel-tungsten plating layers and methods for the production thereof

Abstract

Coatings containing nickel-tungsten (NiW) plating layers are provided, as are methods for forming coatings and NiW plating layers over metallic components. In embodiments, the method includes preparing a plating bath containing a tungsten (W) ion source; inserting at least one consumable nickel (Ni) electrode and at least a portion of the metallic component into the plating bath; and, afterwards, electrodepositing a NiW plating layer over the component surface by energizing the at least one consumable Ni electrode as an anode and the metallic component as a cathode to attract Ni ions and W ions to the component surface. An amount of anode corrosion accelerant in the plating bath is controlled to balance Ni dissolution at the anode to Ni deposition at cathode, as considered in conjunction with any additional Ni ion sources within the plating bath, to achieve a desired composition of the electrodeposited NiW layer.

What is claimed is: 
     
         1 . A method for forming a coating over a component surface of a metallic component, the method comprising:
 preparing a plating bath containing a tungsten (W) ion source;   inserting at least one consumable nickel (Ni) electrode and at least a portion of the metallic component into the plating bath;   after insertion of the at least one Ni electrode and the component surface into the plating bath, electrodepositing a nickel-tungsten (NiW) plating layer over the component surface by energizing the at least one consumable Ni electrode as an anode and the metallic component as a cathode to attract Ni ions and W ions to the component surface; and   controlling an amount of anode corrosion accelerant in the plating bath to balance Ni dissolution at the anode to Ni deposition at cathode, considered in conjunction with any additional Ni ion sources within the plating bath, to achieve a desired composition of the electrodeposited NiW layer.   
     
     
         2 . The method of  claim 1  further comprising selecting the anode corrosion accelerant to comprise chloride. 
     
     
         3 . The method of  claim 2  further comprising adding the chloride to the plating bath as at least one of the group consisting of nickel chloride, sodium chloride, and hydrochloric acid. 
     
     
         4 . The method of  claim 2  further comprising maintaining the anode corrosion accelerant in a range between about 0.0002 to about 0.01 moles chloride per liter of plating bath solution during the electrodeposition process. 
     
     
         5 . The method of  claim 4  wherein maintaining comprises maintaining the anode corrosion accelerant in a range between 0.0008 to about 0.0025 moles chloride per liter of plating bath solution during the electrodeposition process. 
     
     
         6 . The method of  claim 1  further comprising preparing the plating bath to further contain ammonium hydroxide ions in a concentration range of about 1.0 to about 2.0 moles per liter of plating bath solution. 
     
     
         7 . The method of  claim 6  wherein the plating bath is prepared to further contain ammonium hydroxide ions in a concentration range of 1.3 to 2.7 moles per liter of plating bath solution. 
     
     
         8 . The method of  claim 1  further comprising formulating the plating bath and controlling process parameters during electrodeposition of the NiW plating layer such that Ni ions are present within the plating bath in a concentration range of about 0.085 to about 0.307 moles per liter of plating bath solution. 
     
     
         9 . The method of  claim 8  wherein formulating comprises formulating the plating bath and controlling process parameters during electrodeposition of the NiW plating layer such that Ni ions are present within the plating bath in a concentration range of 0.187 to 0.230 moles per liter of plating bath solution. 
     
     
         10 . The method of  claim 1  further comprising selecting the at least one consumable Ni electrode to comprise consumable Ni pellets. 
     
     
         11 . The method of  claim 10  further comprising repeatedly adding fresh consumable Ni pellets to the plating bath as the electroplating process progresses to maintain a ratio between a cumulative surface area of the consumable Ni pellets and a surface area of the contact surface within a predetermined range. 
     
     
         12 . The method of  claim 1  wherein energizing comprises energizing the at least one consumable Ni electrode and the metallic component at a current density between 1 and 5 ampere per decimeter squared. 
     
     
         13 . The method of  claim 1  further comprising formulating the plating bath to further contain citric acid in a quantity ranging from 90 to 150 grams per liter of the plating bath. 
     
     
         14 . The method of  claim 1  wherein the metallic component comprises a connector terminal having a contact resistance, wherein electrodepositing comprises electrodepositing the NiW plating layer directly onto the component surface, and wherein the method further comprises depositing at least one gold layer directly onto the NiW plating layer to decrease the contact resistance of the connector terminal. 
     
     
         15 . The method of  claim 1  further comprising selecting the target W content of the NiW plating to range from about 25% to about 35% by weight. 
     
     
         16 . A method for forming a coating over a component surface of a metallic component, the method comprising:
 preparing a plating bath solution to comprise:
 about 0.0002 to about 0.01 moles of an anode corrosion accelerant per liter of the plating bath solution; and 
 a tungsten (W) ion source; 
   inserting at least one consumable nickel (Ni) electrode and at least a portion of the metallic component into the plating bath; and   energizing the at least one consumable Ni electrode as an anode and the metallic component as a cathode to electrodeposit a nickel-tungsten (NiW) plating layer over the component surface.   
     
     
         17 . The method of  claim 16  further comprising selecting the anode corrosion accelerant to comprise chloride. 
     
     
         18 . The method of  claim 16  further comprising forming the NiW plating layer to consist essentially of:
 between 25% and 35% W by weight; and 
 the remainder Ni. 
 
     
     
         19 . The method of  claim 16  wherein preparing comprises preparing the plating bath solution to further contain ammonium hydroxide ions in a concentration range between about 1.0 to about 2.0 moles per liter of the plating bath solution. 
     
     
         20 . A coating formed over a metallic component having a component surface, the coating comprising:
 an electrodeposited nickel-tungsten (NiW) plating layer formed over and in contact with the component surface, the electrodeposited NiW plating layer comprising:
 at least 50% Ni by weight; and 
 between 25% and 35% W by weight; and 
   at least one gold (Au) layer formed over and in contact with the electrodeposited NiW plating layer, the at least one Au layer having a thickness less than a thickness of the NiW plating layer.