Electroless nickel plating onto stainless steel Q&A's

A. Hi Doug. I'm not sure of the full implications of the term "atomized stainless steel", but I want to warn readers about conducting chemical operations on powders and powdered metals!

Some of the operations that we think we are quite familiar with will proceed hundreds of times faster, releasing heat & hydrogen explosively or almost explosively, when conducted on powdered metals because of their huge surface area compared to their volume. And, of course, the high heat they quickly generate can accelerate the reaction into a runaway. Please conduct any such experiments on very small volumes, and behind a shield inside a laboratory fume hood. Things can proceed very differently than our prior experience :-(

I'm not sure how you will electrolyze the powder for Wood's Nickel plating, but I wonder if the alternative -- sintering first, then vacuum impregnating and plating -- might be better. Luck & Regards,


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

A. Hi again. The reference to electroplating was due to the fact that as discussed on this thread, Wood's Nickel strike or a similar electrolytic process seems to be required for adhesion of electroless nickel onto stainless steel. If the particles are microscopic, it is possible that the whole concept of adhesion strength loses its significance.

I am personally not aware of books or chapters or conferences about electroplating or electroless plating onto powders, but I'm confident that there are individual research papers. Scholar.google.com or www.finishingpublications.com might help.
Luck & Regards,


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

A. I have never heard of "duplex SS". Do you have a more common name for it?

With proper activation of the SS, proper maintenance of the strike solution and no delay getting into the follow on plating, you should not have a problem plating any SS.

Activating some metals like waspalloy, require that attention be paid to the activation step prior to the strike, which is an additional activation as well as the strike.

A. The exact alloy of the stainless will have an effect on the exact preplate chemicals, but it will basically run thru a suitable cleaner, an etch, Wood's Nickel strike and then the EN.

Time between rinses and process tanks must be an absolute minimum or you will have passivation and poor adhesion.

A. An intermediate layer of a Wood's Nickel strike can lead to pinhole corrosion due to the high chloride content. An intermediate layer of a suitable strong acid gold strike bath minimizes porosity and leads to a better corrosion resistance (stainless steel and electroless nickel are quite precious compared to the nickel out of the Wood's nickel strike bath).

A. Hi Sara. I'd say the ideal composition is 240 g/l nickel chloride and 120 ml/l HCl. The reason I'd call it ideal is because, according to the Adhesion chapter in Dini's "Electrodeposition" ⇨
adhesion values of an incredible 70 to 80,000 psi were found to be possible with it.

Regards,

A. It is possible to plate either EN or chrome on any stainless. Some are easier than others. Why would you want to do it or is it practical would depend on what you wanted it to do, which you did not say.

A. In order to plate electroless nickel or another metal deposit one must use a good alkaline cleaner, rinse, acid dip, rinse, and then Electroplate in a "Woods nickel strike" or a low pH sulfamate nickel strike, then plate in the desired plating solutions.

(a Woods nickel strike consists of 240 g/L nickel chloride and 10% by vol. hydrochloric acid. Plate at 40-100 amps/sq.ft.)

A. 316 is a bit harder than 304 to activate but not that hard.
You fail to mention a nickel strike. 316 needs to have a proper Woods Nickel Strike and to not let it passivate before you get it into the EN tank.

A. Hi Yogesh. We appended your inquiry to a similar thread where you will learn that electroless nickel directly on stainless steel will likely be unsatisfactory. You must do a Wood's Nickel strike first. Good luck.

Regards,

"Electroless Nickel Plating"
by Wolfgang Riedel

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A. Hi again, Yogesh. Sure, there are alternatives to almost anything, including Wood's Nickel strike. Uwe Manz suggested a gold strike above, and sulfamate nickel strikes are also possible. But despite two postings, your postings remain too cryptic for me to follow :-)

You're apparently trying to do high phosphorous electroless nickel directly onto type 316SS and it is not working. I and several others here have said that we wouldn't have expected it to work without a Wood's nickel strike. But you are apparently saying it should because of some vague thing you "came to know from the market"?

Please try to clearly state what it is that you believe you heard so that we can discuss it less cryptically and more sensibly. Are you using that product which you were led to believe would work yet it is not working? Are you arguing in general terms that we're wrong and electroless nickel should work directly on your 316SS even though several of us said it won't, and it's also not working for you either?

You can't realistically ask people to do a core dump of everything they've learned from decades of experience, nor to write a book for you covering every possible scenario -- you have to take the time to quite clearly state your question or hypothesis please :-) Thanks!

Regards,

A. Hi Mr. Reza. We appended your inquiry to a thread which explains the activation of stainless steel for electroless nickel plating. You can probably increase the pH by an addition of ammonium hydroxide, but it depends on the bath formulation. But a solid knowledge base is advisable, as even the reliable measurement of pH in an electroless nickel bath can be difficult, let alone the beneficial adjustment of it :-)

Luck and Regards,

A. Hi Gosai. Please start with our " Understanding Chrome Plating" article, which I hope you find interesting!

But if I wanted to start a heat engineering works you'd tell me you couldn't possibly give me the proper process steps one by one. Similarly, our readers would like to help you, but what you are asking is far beyond what the most ambitious reader could possibly cover in a forum response. Sorry! You should retain a plating consultant to get started in such an enterprise; and also hire experienced platers. If you can't do that, you should at the least read several of our "must have" plating books. I'd suggest starting with the Metal Finishing Guidebook, followed by Electroless Plating - Fundamentals & Applications by Mallory & Hajdu [on eBay , Amazon, or AbeBooks affil links] . Best of luck!

Regards,

A. Dan,
I usually see people recommend a Woods nickel strike in order to plate anything onto stainless. Though I wonder, if the electroless nickel plates onto the carbon steel and ignores the stainless, does that still accomplish what you are really after, preventing corrosion on the carbon steel?

A. The EN will plate on the SS without a woods strike, but the adhesion will be unsatisfactory for most.

A. Most important - the strike nickel should have no more than 100-150 ppm iron, otherwise the adhesion will not be good.

A. Hi Randal. Is the object of your work to develop your own unique plating process, or is the object of your work to do something with that electroless nickel plated stainless steel object? The reason I ask is that students often assume that the way one obtains a plating solution is by mixing commodity chemicals together -- but in fact "nobody" in the Western world ever does that ... rather, we buy proprietary plating processes that are the result of decades of careful development effort, and which contain small amounts of numerous trade secret chemicals.

Again, there is absolutely nothing wrong with a project aimed at developing specialized plating chemistry ... more power to you! But if you're just trying to get the darned thing plated, mixing up raw commodity chemicals simply isn't the way.

I'm not sure exactly what "unsuccessful" means. It's not sticking, it's not thick enough, the vessel spontaneously plates out, or nothing is happening whatsoever? But the first issue to address is that you probably can't successfully plate electroless nickel onto stainless without preceding it with a Wood's Nickel Strike. So you might as well do things in the right order from the start. You'll find numerous threads about Wood's Nickel on this site if there isn't enough info on this thread. And are you positive that the article is spotlessly clean to a waterbreak-free condition before you are attempting to plate it? Good luck!

Regards,

A. Hi Renaud. My personal opinion is that there are a couple of problems here. First is the expectation that without prior experience you can "get it right the first time", on a self-supervised training exercise. I think that's optimistic and would suggest that as a minimum you plate & test a variety of scrap and sample parts before you "pull all the electrodes out of this stack".

You haven't mentioned yet whether this is a hobby project or a business project, but it is usual to send such parts to a plating shop with proven competence, rather than attempting to plate them ourself unless there are reasons to the contrary.

It may be a semantics issue rather than people in the plating industry being unfamiliar with a successful method for "activating" the stainless steel; the people writing in the blog you mentioned seem to have a meaning in mind about "activating" the electrode for its ultimate use, whereas when platers speak of "activating" metals they usually mean for subsequent electrodeposition onto them.

Yes, I think you should first do a Wood's Nickel or equivalent strike; I don't think it likely that the electroless nickel plating will properly adhere to these 316 SS electrodes without it. Good luck!

Regards,

Hi again. You may need an anger management course more than a plating course, and that's not my bailiwick so I'm done here thanks.
Luck & Regards,


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

"So are you only experienced in giving advice just to the guys that make metals look pretty or are you going to help us save some time on this plating job on these electrolytic active parts, or is that p'haps too challenging for you old timer?"

Nobody knows everything, but when it comes to Ted and the others who participate on this site, collectively there is more knowledge than you will ever acquire in a lifetime.

I suggest you take your offensive attitude and go away. Far, far away.

! Certainly a unique style of asking for advice!

I'm sure that Hydroxygas PTY would be unimpressed with how you present yourself in a public forum. Certainly somewhat less artfully than a "Marketing" person should!

The take home message is "politeness" especially when asking for advice, will always lead to better results!

  Thanks for the kind words, cousin Masih. Remember that trying to teach can be the best way to learn, especially when surrounded by your peers like on this site. I have many times posted something here confidently, only to be corrected by others -- and learned a lot from my ignorance :-)

Regards,

A. Hi Michael

The purpose of any spec is to ensure that the finish meets design requirements. You cannot change a spec just because it is easier to achieve and we have no way of knowing what is appropriate. There has to be some reason why 304 needs additional plating.
You need to ask the design engineer why the original spec was called for.
You would not believe the number of times I have found a spec called .."because that is what the last part had".
Or it could be for a very good reason.

A. I always question the wisdom of plating on stainless, since the point of the alloy is its enhanced corrosion resistance without the need for a coating, and the surface must be activated (the opposite of corrosion resistance!) in order to make the plating happen.

It stands to reason that a less expensive steel could be substituted as the substrate with no effective change to the final plated surface.

I'm not sure if the thought process is "but we always use stainless for this kind of part", without realizing that the need for plating negates the original purpose of using stainless.

A. Hi Michael. The plating shop is probably right that 0.0015" inches is awfully thick for such an application and may be contributing to the problem of flaking. But I would start by determining for fact that the plating shop did perform the Wood's Nickel strike step, and any related processes that may have affected things, rather than simply accepting "we treated it as stainless steel even though you didn't tell us to".
Luck & Regards,


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

A. Hi Anthony. Why not make the plunger out of type 316 or other stainless which can withstand the pond water exposure?

Although it's possible that the adhesion is not good enough (thus explaining why plating is being knocked off), it sounds equally likely to me that the impact may be 'denting' the softer stainless steel and you are getting an eggshell effect, or as our friend Guillermo expressed it on a different thread, a sheet of glass on a soft sofa. If you can't make the plunger out of a better grade of stainless, perhaps you could make it of a heat treated plain steel, to which the electroless nickel plating would adhere better as well?

Regards,

A. Hi Joe. If you're saying that that's what was done, sure, it would be a major problem!

But if you're just starting to speculate about possible causes of poor adhesion, it is very hard to get reliable adhesion onto stainless steel and it probably requires a Wood's Nickel Strike before the electroless nickel. Good luck.

Regards,

A. Hello Ho,
In my opinion the best discussion of Wood's Nickel and adhesion is in Jack Dini's "Electrodeposition" ⇨
and getting good adhesion between the Wood's Nickel and the stainless substrate is the most critical interface. But after a quick rinse, you must immediately do the next steps of Electroless Nickel and Copper plating because nickel plated surfaces passivate quickly. You might want to research whether a silver "strike" bath is required between copper plating and silver plating. Heating treating at any point will deactivate the surface and ruin the adhesion.

I'm not sure which steps in your project you are required to do personally, but just a reminder in case you didn't know it: plating is very jobshop oriented and the usual practice is to send parts out to a plating shop for plating. Becoming good at SST pretreatment, then Wood's nickel strike, then electroless nickel plating, then copper plating, then silver striking/plating is fodder for at least thesis projects, not one :-)

Regards,

A. Hello again, Ho.

Note that palladium seeding applies to non-conductive substrates, not metallic ones -- forget that completely.
Your second posting is now making me think that you are saying you have to build 3 of something for some reason -- one each with electroless copper, electroless silver, and electroless nickel (because I've personally never heard of doing electroless nickel followed by electroless copper).

Please start with a half page description of exactly what you want to build and why because all we're doing is confusing each other when I don't correctly understand what it is that you want. Thanks!

Regards,

A. Hi again. Stainless steel instantly forms an oxide layer on it, and electroplating with ideal adhesion requires the formation of metallic bonds between the substrate and the electroplated coating, which can't happen with an oxide layer in between them. Wood's Nickel Strike is a way of hopefully dissolving that oxide layer in acid and replacing it with nickel. Therefore (to my understanding) it is always required when plating on stainless steel (although there are alternatives like other nickel strike formulations or striking with gold).

Anodic and cathodic cycles mean, respectively, running the power supply with the workpiece being the positive electrode and the negative electrode. Yes, some sources suggest a short period of anodic current first; but many shops do not do it, and that single question of whether the anodic is necessary or beneficial could probably justify it's own research project :-)   I'd simply skip it.
As previously mentioned, personally I think the best explanation of Wood's Nickel Strike is in Dini's "Electrodeposition" ⇨

I am not personally familiar with the use of palladium-tin catalyzing on stainless steel; I have only heard of it being used on non-conductive substrates. To summarize, I think the right thing to do is to clean and Wood's Nickel Strike all three of your pieces, then make sure nickel is catalytic (initiates the deposition) for your electroless copper and electroless silver, and to proceed to deposit the three electroless plating solutions onto the nickel strike.

Regards,

A. As others recommended, you need a nickel strike prior to the EN.
No need for anodic/cathodic, only cathodic.
The Palladium-Tin is used for non conductive substrate.

A. Hi Ben. The first thing I'd try is higher current density.

Luck & Regards,


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