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Contrastless Ni plate with Electrolytic Ni Plate

We are looking for documentation that contrasts the difference between electroless Ni plating and Electrolytic Ni plating in such areas as corrosion protection, adhesion, porosity, time to plate etc.

Alfred F. Weyhreter
aerospace - Bethpage, New York
2005

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First of two simultaneous responses --

So many variables, a full answer to your question would fill a large book. Can you pose a more specific inquiry?

Jeffrey Holmes, CEF
Spartanburg, South Carolina
2005

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Second of two simultaneous responses --

Probably a good starting point would be Properties of Electrodeposited Metals and Alloys [affil link to Amazon or on AbeBooks affil links] by W. Safranek, available through this site.

Guillermo Marrufo
Monterrey, NL, Mexico
2005

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December 5, 2011

Hi, Alfred. While Jeffrey and Guillermo are correct that there is a lot to the question, I think we should briefly address it--

Electrolytic nickel plating is the familiar electroplating of nickel metal, whereas electroless nickel is the autocatalytic deposition of a nickel-phosphorous (or less commonly a nickel-boron) alloy.

"Autocatalytic" means that the electroless plating solution contains reducing agents capable of reducing the ions in solution into nickel metal, and that the metal that is deposited can serve as the catalyst necessary for that reduction process to proceed. This means that the thickness of the deposited coating is not limited by the substrate becoming covered, because the nickel it is now covered with can continue catalyzing the deposition process.

Some of the advantages and disadvantages stem from the application method. For example, you can control the thickness of nickel electrolytically deposited in different areas of the part by arranging things to give a different current density to different areas. But usually you seek uniform plating thickness and that is much easier to achieve with electroless nickel. It is also significantly easier to electroless plate internal diameters than to rig up anodes inside them to electrolytically plate. Electrolytic plating can be sort of an "equilibrium" process, where you don't need to do anything to the solution, just keep adding anode metal. Electroless plating isn't like that because the reducing agents (among other things) are consumed by the process. For this reason and other reasons, electroless nickel is much more expensive.

Electroless nickel has phosphorous in it and is rather a "glassy" coating which is slightly less porous and more corrosion resistant thickness for thickness, but is usually significantly more uniform in thickness, and therefore less subject to corrosion at thin spots. Electroless nickel can be very hard and wear resistant.

Adhesion should not be an issue, as both processes form excellent deposits. Electrolytic nickel can deposit faster: 20 minutes to an hour wouldn't be unusual whereas 2 hours is a common plating time for heavy electroless deposits.

Jeffrey's request for a more specific inquiry can correctly be interpreted to mean that once you mention what you want to plate and why, much of the mystery will go away. That is, it's fairly unusual to have to wring your hands guessing which way to go; certain types of parts are almost always electrolytically plated, and other types almost always electroless plated. As an example, when doing coper-nickel-chrome plating you'll always do electrolytic nickel plating; and when doing "wear" parts, including electrical contacts, you'll almost always do electroless nickel plating.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

adv.