Zinc vs White Nickel

[tnkayaker]

I have been asked to find out the difference in corrosion resistance between zinc plating and nickel electrodeposition. I realize that it is dependent on plating thickness so let's use a thickness of .0002".

Any insight is appreciated.

 

[swall]

What is the substrate material?

 

[tnkayaker]

12L14 steel

 

[swall]

From "Corrosion and Corrosion Control" by Uhlig, a Table shows corrosion of zinc at .202 mils/yr in an industrial environment and .063 mils/yr in a coastal environment. For nickel, those figures are .128 and .004 respectively.But that's not the whole story. Nickel plating in the range you cite would have to be non porous to be effective. Zinc platings can be enhanced with chromate type conversion coatings. Zinc on steel is sacrificial, which means that once perforated, it will still protect the steel substrate. Nickel, if perforated, will allow the steel substrate to corrode. If the plated part will be in contact with other metals, then galvanic corrosion also needs to be considered.