Low hydrogen embrittlement zinc/nickel plating for high strength steels

Abstract

The invention provides a method for producing a corrosion-resistant article, where the article is conductive and subject to hydrogen uptake during electroplating of a coating. The method comprises electroplating a zinc/nickel coating on the article in an aqueous, basic plating solution containing zinc and nickel ions. The method uses an electrolyte in the form of a soluble hydroxide salt with the weight ratio of zinc ions to nickel ions in the solution being sufficient to provide the coating comprising from about 85% to about 95% by weight zinc, and about 5% to about 15% by weight nickel. The plating solution is substantially free of brightening agents which retard hydrogen bake-out.

1 . A zinc nickel plated article comprising a substrate and a zinc nickel alloy plating on the substrate, wherein the substrate is a high strength low alloy steel, wherein the plating is 85-95% by weight Zn and 5-15% by weight Ni, and wherein the article meets the corrosion specification requirements of ASTM B-17 and the low embrittlement specification requirements of ASTM F-519, Type 1a.2. 
     
     
         2 . A plated article according to  claim 1 , wherein the substrate is 4340 steel alloy. 
     
     
         3 . A plated article according to  claim 1 , wherein the substrate is 4340M steel alloy. 
     
     
         4 . A plated article according to  claim 1 , wherein the article is a part of a commercial aircraft component. 
     
     
         5 . A plated article according to  claim 1 , wherein the plating is characterized by a density sufficient to provide the observed corrosion resistance, and by a porosity sufficient to provide the embrittlement resistance. 
     
     
         6 . A plated article according to  claim 1 , wherein the weight ratio of Zn in the plating to Ni in the plating is 10:1 to 11:1. 
     
     
         7 . A plated article according to  claim 1 , wherein the high strength low alloy steel is characterized by a tensile strength of 220 ksi or higher. 
     
     
         8 . A plated article according to  claim 1 , wherein the high strength low alloy steel is characterized by a level of alloying of Cr and Ni below 10%. 
     
     
         9 . A zinc nickel plated article comprising a substrate and a zinc nickel alloy plating on the substrate, wherein the plating is characterized by a morphology as shown in  FIG. 2   a.    
     
     
         10 . A plated article according to  claim 9 , which meets corrosion specification requirements of ASTM B-17 and the low embrittlement specification requirements of ASTM F-519, Type 1a.2. 
     
     
         11 . A plated article according to  claim 9 , wherein the plating has a weight ratio of Zn:Ni in the range of 10:1 to 11:1. 
     
     
         12 . A plated article according to  claim 9 , wherein the substrate is a high strength low alloy steel. 
     
     
         13 . A plated article according to  claim 9 , wherein the substrate is a stainless steel. 
     
     
         14 . A plated article according to  claim 9 , wherein the substrate is a carbon steel. 
     
     
         15 . A plated article according to  claim 9 , wherein the substrate is AISI 4130. 
     
     
         16 . A plated article according to  claim 9 , wherein the substrate is copper or graphite. 
     
     
         17 . An aircraft component comprising a zinc nickel plated article, wherein the plated article comprises a high strength low alloy steel substrate with and a zinc nickel plating on the substrate, wherein the substrate is characterized by a tensile strength of 200 ksi or higher and the plating is 85-95% by weight Zn and 5-15% by weight Ni, and wherein the plated article meets the corrosion specification requirements of ASTM B-17 and the low embrittlement specification requirements of ASTM F-519, Type 1a.2. 
     
     
         18 . An aircraft component according to  claim 17 , wherein the plating on the substrate is characterized by a morphology as shown in  FIG. 2   a.    
     
     
         19 . An aircraft component according to  claim 17 , wherein the zinc nickel plating has a morphology characterized by a microporosity that permits entrapped hydrogen to migrate out of the plating. 
     
     
         20 . An aircraft component according to  claim 17 , wherein the zinc nickel plating comprises zinc and nickel in a weight ratio of from 10:1 to 11:1. 
     
     
         21 . An aircraft component according to  claim 17 , wherein the substrate has a tensile strength of 220 ksi or higher. 
     
     
         22 . An aircraft component according to  claim 17 , made by a process comprising electroplating a zinc/nickel coating on a low alloy, high strength steel from an alkaline plating bath,
 wherein the bath comprises zinc and nickel at a level to produce a plated coating containing 85-95% by weight zinc and 5-15% by weight nickel,   wherein the bath comprises an effective amount of a nickel complexing agent;   wherein the bath comprises less than 10 ppm of total organic material other than the complexing agent; and   wherein the coating has a dense, porous morphology that provides corrosive resistance on account of its density and resistance to hydrogen embrittlement on account of its porosity.   
     
     
         23 . An aircraft component according to  claim 22 , wherein the bath comprises a nickel complexing agent selected from diethylene triamine or a combination of diethylene triamine and triethanolamine. 
     
     
         24 . An aircraft component according to  claim 22 , wherein the bath comprises a nickel complexing agent selected from ethylenediamine (EDA), diethylene triamine (DETA), triethylenetetramine (TETA), N-hydroxyethylenediamine (HEEDA), diethanolamine (DEA), triethanolamine (TEA), N-methylethanolamine, 2-aminopropanol, nitrilotriacetate, ethylenediamine-tetraacetate, and diethylenetriamine pentaacetate. 
     
     
         25 . An aircraft component according to  claim 22 , wherein the bath comprises less than 1 ppm of total organic material other than the complexing agent. 
     
     
         26 . An aircraft component according to  claim 22 , wherein the electroplating is carried out at a cathode current density of 30-60 amperes per square foot and a bath temperature of 65° F. to 85° F.