Nickel plating / striking on stainless steel

A. In my case I don't like to electroclean reverse; it does passivate stainless steel, just cathodic electrocleaning.

A. Hello Daniel,
Most shops use HCl pickling on steel before Ni strike, not a sulfuric dip. I also agree that a cathodic clean is the way to go.

A. Maybe you have left the anodes in, and the nickel concentration increases, and you convert an inefficient STRIKE solution into an efficient PLATING solution which will not bond. Take your anodes out when not in use, titrate and adjust the metal down to 16 oz/gal nickel chloride and 32 fluid ounces per gallon HCl.

A. I would like find out blister base -- substrate to Ni strike, or bright nickel to other nickel, or chrome layer. I think you have a cleaning problem; soak clean, follow up by anodic electroclean and anodic acid (10%) sulfuric acid (CLEAN).

Hi Monica. I'd like to try to help you but your questions are too brief for me to understand.

Regards,

A. Monica,
Plating on SS material is a tough task.
It is an inert metal.
Try with Wood's nickel strike prior to nickel plating.

A. Hi Lee. We appended your inquiry to a similar thread where the question of why you might plate stainless steel is already somewhat answered -- for example, it's a better electrical contact surface, and it's more solderable. Unfortunately, 3rd parties can only guess why the designer wants the stainless steel nickel plated, and our guesses may be wrong.

There is no way we can say whether nickel plated stainless or tin plated CRS is better for an unknown application, but the tin plated CRS is probably a good deal less expensive. Best of luck.

Regards,

A. Hi Rejaul. Have you enjoyed success gold plating other items? What other items? Were they made of stainless steel? Does your watch now have a nice shiny adherent plating of nickel on it?

Regards,

Q. Hey ted,
No this is the first item I am gold plating. How can I tell if there is a layer of nickel on the watch? It looks exactly the same to me. I assume there must be a step I'm missing

A. Hi again Rejaul. You're welcome to attempt anything you want to attempt. But if you have never done any plating and your first attempt is going to be on an expensive stainless steel item of unknown composition, you have a difficult task in front of you both because of potential damage and because stainless steel is difficult to plate.

Still if you are running electricity to the part, you are moving electrons from the anode to the cathode and something has to happen at the anode and cathode as a result because Faraday's Law of Electrolysis won't be violated. Tell us about the bubbles you're seeing in the nickel plating tank and in the gold plating tank.

Regards,

A. You need a high chloride bath Nickel Wood's Nickel

                  Range          Optimal
 Contents: Nickel 80- 96 gr/lt,  88 gr/lt
 Nickel Chloride 420-467 gr/lt, 434 gr/lt
 Chlorhidric Acid 70- 82 gr/lt,  75 gr/lt
 3 to 5 volts

I hope this can help you. Regards.

Q. Hello Ted, can you please elaborately explain to me How The Above Composition Has Come And How It is Useful
Best Regards

Phani kartheek
- Hyderabad, India

---

Hi phani. The Wood's Nickel Strike was invented and developed by Donald Wood, a founding partner of Hill-Cross Company [a finishing.com supporting advertiser] in West New York, NJ.

As a young man I had the pleasure of knowing Don. He loved pumpkin pie, and I lived near a famous baker of them; in return for bringing him a pumpkin pie a couple of times, he was kind enough to show me some of his achievements :-)

The primary purpose of the process is to allow plating on stainless steel.

Regards,

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

A. Hi Suzanne. We have some 50,000 threads here and I can't easily find the one where someone claimed that 90 g/l is the upper limit. But the most obvious thing is that if the nickel concentration is too high, the process may function as a plating bath without attacking and activating the stainless, and you'll have low adhesion.

But please tell us your own situation -- it's tough to predict all the things that might go wrong in 101 scenarios if the process gets out of control and the nickel is too high :-)

Regards,

A. Hi John. When a non-precious metal is exposed to the atmosphere, the surface of the metal reacts with the oxygen and sulfides in the air and forms reaction products on the surface. These reaction products are not metals and tend to not be conductive. The resistance offered by this skin of reaction products can interfere with the passage of electrical current. The tarnish that forms on the surface of nickel is not as thick, resistive, and problematical as that which forms on stainless steel ... but whether that is because of the chrome or the iron in the stainless steel, I don't know.

Regards,

Q. Thank you for the quick reply, Ted.

It's my understanding that for stainless steel, this reaction is also known as a passivation layer, and is made of Chromium Oxide (Cr2O3), and is extremely thin. Stainless steel, even with the passivation layer, isn't all that resistive, though Cr2O3 has about 50x the resistance of SS, which itself has about 10x the resistance of Nickel, which is about 4x the resistance of Copper. Because the Cr2O3 layer is very thin, it doesn't contribute very much to the overall resistance of the SS structure (in this case, a screw). From what you're saying, it sounds like the purpose for Ni plating SS for electrical applications is to reduce the surface resistance from the passivation layer. Our experiments have shown that in a static (non-vibe or shock) scenario, the electrical connection through the non-plated screw is just fine. So it seems that maybe there's something more to it. Perhaps it has something to do with the hardness of the Cr2O3 layer (connector pins are often plated with soft metals like gold to improve reliability)?

Anyway, when we nickel plate the screw, I assume the passivation layer still exists (between the SS and the Ni), and that the plating doesn't strip it away... or does it?

Thanks again.

A. Hi. The Wood's Nickel Strike simultaneously removes the oxide layer on the stainless steel while depositing nickel in its place. The purpose is to remove the oxide layer so good adhesion can be achieved.

Regards,

A. Hi.
1. You must do surface cleaning before you can do nickel plating.
2. There is nothing wrong with sandblasting or bead blasting as the first step in preparation, but it may not be necessary. But after that you must alkaline electroclean, rinse, dip in dilute hydrochloric acid, rinse, and do a Wood's Nickel Strike.
3. The purpose of the sequence is to get the nickel plating completed while the surface is still clean and active. That means any delays are bad because the surface can get dirty again or passive again. After you have achieved a successful pattern of pretreatment, plating, and brazing you might experiment with allowing some amount of time between steps but -- until you do -- allowing any time at all is an impediment and a complicating factor in a process that you haven't yet tamed.
4. The first pattern I would try would be blast, alkaline clean, rinse, HCl activate, rinse, Wood's Nickel Strike, rinse, Nickel Plating.
5. I have no brazing expertise and cannot answer.
6. Wood's Nickel Strike is a very acidic, dilute, nickel plating solution intended for activating stainless steel. The theory is that it is very difficult to keep stainless steel from instantly tarnishing with a tarnish layer which makes proper adhesion of plating impossible, but a Wood's Nickel Strike can dissolve that thin tarnish layer, while simultaneously depositing in its place a thin layer of nickel. The thickness of Wood's Nickel is too low to be useful for most purposes except as a base layer for subsequent nickel plating.
7. "Nickel flash" is a general term, rather than a specific term, and it just refers to a thin layer of nickel plating, generally too thin to serve as a final finish on its own. A Wood's Nickel Strike would be an example of a nickel flash.

Good luck.

Regards,

Q. SIR, I HAVE NICKEL PLATED MY STAINLESS STEEL 304L FOR VACUUM BRAZING -- IT WAS SUCCESSFUL :)
THANK YOU SIR.
SIR I HAVE SOME PROBLEMS:
1) IS IT NECESSARY TO CLEAN THE NICKEL PLATED SS 304L SURFACE BEFORE BRAZING? (PLEASE ELABORATE THIS POINT)?
2) IF YES ! THEN HOW AND WITH WHAT MATERIAL?

5. I have no brazing expertise and cannot answer :-)

Regards,

A. Hi Devendra. Yes, once you have properly applied the Wood's Nickel strike or other nickel strike to the 304 stainless steel as discussed in this thread, you can proceed with nickel plating and then chrome plating. The life should be more than acceptable, but it doesn't have an expiration date like bread or pharmaceuticals. There are large texts about testing, but you probably need to test for adhesion and for corrosion resistance as a minimum. Please name some of the electroplating texts in your library and we can refer you to specific chapters; if you don't yet have any plating texts, please go to our "Must-have books" section and consider a couple. Good luck.

Regards,

A. Hi Joseph,

Have you heard of a thing called the REACH regulations? In there, restrictions apply to the use of certain substances in certain ways of use (Annex XVII Restrictions). Nickel is restricted for use on items in intimate contact with the skin unless it can be shown the release of nickel is less than a certain value (0.5 micrograms per square centimeter per week). If you cannot verify that the release of nickel is below that figure you are breaking the law in the European Union.

To be honest, if you have stainless steel you shouldn't bother with nickel plating it at all. If it was me I would engrave directly into the stainless steel and then if I felt it necessary passivate with a citric acid type passivation solution.

A. While Mr Terry's advice was extremely important if you are making jewelry "rings" to be worn on people's fingers, I read the context differently, in that I have no way to know how you will use the "rings" but that you have an adhesion problem of nickel to stainless steel. If that is the case, then your plater has to tighten up his control of his nickel chloride strike. One pound per gallon nickel chloride and 1 quart per gallon HCl, rolled depolarized nickel anodes (NOT S-rounds), bagged, removed when not in use. And he has to rack them individually, barrel plating probably will not activate the stainless steel.

A. Joseph,
I'll split the difference between the two preceding comments.

Stainless steel is very difficult to plate on, so probably your plater is not doing the preparation correctly which is causing the issue.

The REASON stainless is difficult to plate on is because it's quite resistant to reaction with other things, which is the entire point of stainless steel in the first place. Which is to say, there is no reason to pay the extra money for stainless steel if you're just going to cover it over. Mild steel is cheaper to buy and cheaper to plate. Use stainless if you want the metal itself, rather than a coating, to be the exposed surface.

A. I assume the reason for nickel plating the stainless steel is to give it a nickel look. I would suggest you engrave the stainless steel, then have someone apply a nickel PVD finish. The finish is not really nickel, but a hard carbo-nitride of titanium, zirconium (most likely) or chromium. We do this regularly on stainless steel watch parts.

A. The last few responses were more then enough to began resolving your issues. I couldn't help but think why not engrave your "rings" prior to the plating process? In my experience with decorative plating it is best to have all tooling, cutting, and polishing done prior to laying down any plating on the the surface. Seems to obvious so there is probably a reason you are not doing it already but just in case it was overlooked.

A. Hi Max. If it's done right the plating will not come off -- but how are you realistically going to find a plating shop which will do it right? If you can find one that specializes in nickel plating of stainless exhausts, fine; but if not, do you really want to risk repeatedly mounting and dismounting it, and fighting over it for months if the plating does bubble or come off? I'd probably go with nickel plated steel myself.

Is this a car or a motorcycle? It should be understood that the more interesting details which are included in your posting, the more you will draw the interest of the readers and inspire them to respond.

Regards,

It's a 1923 Sports car.
Three pipes come through the hood and 3 inch exhaust pipe runs around the outside of the body, so it's a feature of the car.

A. Sorry Rajesh, you will not get proper adhesion if you replace the nickel strike with copper plating :-(

Regards,

A. Hi Vasanth. The fact that you are doing Wood's Nickel at 1.5 volts tells us that the workpiece is quite close to the anode, probably indicating that that you are dealing with a small part in a small tank, but it doesn't tell us the important part, the current density, which should probably be about 1000 A/dm2.

When a multi-layer plating does not adhere, it could be poor cleaning, poor Wood's Nickel, passivation after Wood's nickel, laminated bright nickel plating, passivation after bright nickel, or poor gold plating. Usually the most productive thing to do is to try to cut the problem down to size by doing your best to analyze where the separation occurs. Scrape off the blisters, and study the substrate in the blistered area, and the underside of the blisters, to try to ascertain whether there is no nickel on the substrate, a tiny amount consistent with successful striking, or a large amount consistent with laminated nickel plating.

Regards,

A. After you check what Ted says above, then , if you have left the anodes in the tank, most likely the metal content has climbed and the previous in-efficient strike has now become an efficient plating solution and dos not activate whatever the base. Information for the proper control of a nickel chloride strike is available.

A. Sorry Abu, that's probably a no. Stainless steel instantly forms an oxide surface to which plating will not adhere properly. The Wood's Nickel is a strong acid which can dissolve that oxide while the nickel plates onto it. I strongly doubt that any electroless nickel solution can attack the oxides that way.

Luck & Regards,

A. Hi Jeff. While I don't know your parts, a 60-min soak clean followed by an electroclean sounds like a pretty robust cleaning cycle ... unless there are silicones about, in which case no amount of cleaning is robust enough.

So at this point I would suspect the nickel strike more than the cleaning. And, since you've already changed the solution, I would suspect inadequate current density. If you get a chance, please take a look at the adhesion chapter in Electrodeposition [affil link on Amazon or on AbeBooks], which seems to indicate that you almost can't have too high a current density, but too low leads to "iffy" adhesion.

Luck & Regards,

A. You did not mention an acid dip following the alkaline cleaner, so I have to wonder how much neutralization you are doing to the nickel chloride strike. Inspect the raw metal with a 10X loop and look for holes. If your anodes are S-rounds then you must take them out between runs to prevent the nickel metal increase which converts the inefficient "strike" to an efficient non-bonding "plating" solution, but you seem to handle that buy replacing the strike, now go back and use Rolled Depolarized anodes for the strike. Tell us the alloy, is it "leaded"?

Thank you for the great info Ted!
I had been previously told the nickel was slightly high, about 1 unit over (1g/L). I checked the actual number today, and it is 15g/l over our target. Bath has been cut, hopefully that solves our issue.

Robert, thank you for the info!
I inherited this system, which does use nickel rounds instead of bars. I have sourced the bars, and will begin testing them once this current issue is solved. I will also look into an additional acid dip to follow our alkaline/e-clean process.

A. Hi Jeff,
You have Nickel peeling problem on stainless steel substrate, I think your process step may be revised , 1) soak 2) reverse current in electrocleaner 3) rinses 4) 10% sulfuric acid dip with 4-6 volt or 700-900 amps depends on your work load for 30 seconds 5) rinse 6) Wood's nickel strike.
Good luck Jeff.

A. Hi Shinji
We appended your question to a long thread on the subject which hopefully will answer all.

But in brief, plating must be done on metal -- clean, raw, non-oxidized metal -- so that metal can grow on metal. But stainless steel, due to its nickel and chromium content, instantly oxidizes and renders this difficult. Nickel strikes, especially Wood's Nickel, are highly acidic and dissolve those oxides and keep them from forming -- while simultaneously depositing a thin layer of nickel on the parts to make them more plateable.

But remember that nickel passivates fairly quickly itself, so the nickel plating must follow the nickel strike fairly immediately.

Luck & Regards,

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

A. Mooney has got you covered. But when you say "not consistent", a frequent problem is that people leave the anodes in the tank when not in use, the nickel content goes up, the low efficiency "strike" becomes an efficient "plating" solution and does not "stick".

A. Hi Shinji
It is necessary to strike the stainless steel; it is permissible to strike the whole thing is that's the most practical way to strike the stainless steel. Luck & Regards,

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

A. Hi again Shinji. Yes, brush striking or 'bonding' is certainly possible. However, it may not be easy.
Luck & Regards,

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

A. Hi Shinji
There are options to strike the Stainless Steel with brush plating, but it looks like a hassle and probably it is not practical in your case.
If the whole part is steel and only some areas are stainless steel - it is much simpler and easier just to strike the whole part, rinse and immediately plate electroless Nickel on top of the strike.
Plating has to be done as soon as practically possible after the Ni strike. Keep the part wet all the way from Ni strike-to rinse-to ENi.
Good luck.