Electrical conduction properties of nickel plating

A. Hi Vasco. We have appended your question to a thread where Sjamp VanEsch has already answered your question about the conductivity of electroless nickel.

But you should be very cautious about your early decisions, so you might want to consider retaining a plating consultant if you will be doing a lot of plating. Here are some issues I'd be concerned about:
• getting sufficient adhesion if you cannot use electroplating might be a problem because a Wood's Nickel Strike (an electrolytic process) is the standard way of getting good adhesion on stainless steel.
• electroless nickel is much more expensive than electrolytic nickel; if the parts are small & few, you may be able to ignore this, but in general you never switch from electrolytic nickel to electroless nickel to save money :-)
• when the complexity of electrolytic nickel concerns you, you need to know that electroless nickel has plenty of its own complexities :-)

You might want to get plating shops to quote on these parts before you install a system of your own, so you know what will be a reasonable expenditure for an in-house system. Good luck!

Luck & Regards,

Vasco,

Electroless nickel would be the best to plate inside of this tube. You are correct in that regard. However, for electroless nickel to adhere to stainless steel, you must first plate with a nickel strike. This is an electroplating process and a very inefficient one at that.

Unless someone else has a better idea about how to gain adhesion with electroless nickel over stainless in a 2mm diameter tube, I would suggest a different material for your tube.

Why does your tube need to be stainless? If you use a carbon steel tube and plate the inside and outside of it, would that work instead? The part would then have a similar look to stainless steel. Carbon steel also conducts current better than stainless. It could be a "win-win" if you switched to a carbon steel tube that would not require a nickel strike before the electroless nickel plating.

A. Dear Mr Wanlass,

There is a difference in electrical conductivity properties. The specific resistance of electroless nickel with 6-7% P is about 50-70 micro-ohm-cm, in general the more phosphorus the more resistance. For example 3% P gives a resistance of about 30 micro-ohm-cm, 8-9% P gives a resistance of about 90-110 micro-ohm-cm. Heat treatment can lower the resistance a lot. Also the amount and kind of additives in the plating bath influences the electrical resistivity.

The specific resistance of bright nickel is about 12-19 micro-ohm-cm, depending of what kind of bath(chloride,sulphate) and what additives are used. Pure nickel, plated out of a bath without any organic additives,has a specific resistance of about 7-8 micro-ohm-cm. Plating silver over nickel or NiP gives excellent electrical properties and provides good corrosion resistance.

Kind regards,

A. Hello Sanjay. Two different types of resistances are involved in contact applications: the internal resistance of the metals, and the contact resistance where the two surfaces are touching, which is high because of dirt and oxides on the surfaces, and incomplete contact.

When two steel surfaces contact each other out in the open air, there is high resistance because of the rust, dirt, and rough surfaces which the electricity must traverse. When two nickel plated surfaces contact each other, the resistance is much lower because the nickel surface is smoother and the oxide film is much thinner. When steel is electroplated with nickel, there is true metallurgical joining of the two surfaces, and very low resistance at that joint. So you will find lower resistance and a much more satisfactory contact by nickel plating the steel surfaces.

Hi cousin Waseem. The answer to question 1 from June 28th is yes; I can't answer the others from that date.
I think question 1 from June 29th is asking whether nickel plating followed by silver plating can be done electrolytically, and yes it. Again I can't answer question 2.
Question number 3 is probably not really answerable. On a microscopic scale, the smaller contact may actually have more area in contact: knife edge contacts are often used for better contact even though the contact area is small, and 'wiping' contacts are often employed where flat contacts are used. So minimum may be best for contact, but the area of brass or steel carrying the current may be more important.

As you see, nobody has responded despite this page being viewed thousands of times. It usually will work better if you can engage readers in conversation by introducing yourself, explaining what it is you are working on, and why these questions have come up. Nobody likes 'flash card quizzes', and nobody likes publicly announcing "I don't know", which they'll have to say even if they know the answer to 5 of your questions but not all 6 :-)

Regards,

"The Properties of Electrodeposited Metals and Alloys"
by William Safranek

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A. Hi Allen. Safranek includes a 75-page chapter on the properties of electroplated nickel.

Regards,

A. If you are looking for wear resistance of nickel plating you may consider using an electroless nickel plate.