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topic 11290

Difference between Nickel plating and Electroless Nickel plating


A discussion started in 2001 but continuing through 2018

2001

Q. Can anyone explain the end physical properties difference between electroless and electrolytic nickel plating. Would hard chrome offer improved corrosion and/or physical properties.

Glen McIntosh
- Wisconsin


Electroless Plating
by Mallory & Hajdu

from Abe Books
or
Amazon

2001

A. Electroless nickel is far superior to electrolytic nickel for corrosion resistance. That is because it is an amorphous glass-like nickel phosphorous alloy and because the thickness distribution is far superior so there will be no thin spots. Hard chrome is not really corrosion resistant since the cracks extend through to the substrate.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


2001

A. Electrolytic nickel is deposited using DC current, while Electroless Ni is an autocatalytic deposition. Electroless Ni produces plating of uniform thickness all over the part, while electrolytic Ni plates a thicker deposit in high current density areas. Electrolytic nickel is more ductile than electroless, which tends to be brittle and glasslike. Typical electroless Ni baths use hypophosphite reducing agents and deposit phosphorus along with the Ni. Mid-Phosphorus (5-8%P) deposits are bright, hard, and magnetic as deposited. High phosphorus (9-15%) deposits are nonmagnetic as deposited, semi-bright, and slightly softer than mid-phos. High-phos Ni has greater corrosion resistance than lower phos deposits. All electroless Ni deposits can be altered by heat treatment at temperatures as low as 800 °F. Electrolytic deposits are Ni-Sulfur alloys if a brightener is used. The sulfur in the deposit reduces corrosion resistance.

Michael Brewington
- Salisbury, Maryland


2001

A. Hi Glen:

You already got two professional answers, but adding to Ted and Mike, here are some other physical properties that you asked for. Chromium is harder (900-1100 HV), has a lower thermal expansion (around 8/1000000) and has a higher melting point (1875-1920 °C) than any nickel, either electro or electroless. Most of the time it is stressed and cracked, so it is not an impervious barrier to isolate substrates chemically, but it will resist nitric acid and other strong oxidants better than either electro or electroless nickels.

Guillermo Marrufo
Monterrey, NL, Mexico


2005

A. There is one thing that I would like to add on top of the comprehensive explanations that you already received, the low phosphorous EN deposit is almost as hard as hard chromium. That is why some platers use it as a substitute to hard chrome.

sara michaeli
sara michaeli signature 
Sara Michaeli
chemical process supplier
Tel-Aviv, Israel



2005

A. I just want to add one important thing that should be taken in consideration now with RoHS and WEEE regulations : most of the formulations of these electroless Nickel bath use Lead and Chromium as stabilizer and brightener. And these 2 elements co-deposit with the Ni alloy.
Some substitutions are coming on the market but are not yet common.

Franck MASETTO
- China

Ed. note: Franck's posting is a few years old and most suppliers now offer electroless nickel free of lead or cadmium stabilizers.



March 25, 2009

Q. I want to know which method takes more time electrolytic or electroless.

dilip patel
plating shop employee - gujarat-jamangar, India


"Nickel and Chromium Plating"
by Dennis & Such

from Abe Books
or
info on Amazon

March 30, 2009

A. Hi, Dilip. Electroless nickel usually takes significantly longer. Plating times of 1 to 2 hours or more are fairly common, while a half hour is a long time for electrolytic nickel plating. But please don't read too much into that answer, because 'productivity' is almost never any consideration at all in choosing electroless vs. electrolytic.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



January 15, 2012

Q. Hi.

We are using MIL standard QQ-N-290A [link is to free spec at Defense Logistics Agency, dla.mil] for Ni Plating. It states Nickel Plating (Electrodeposited) on its header. I cannot make it out whether this is Electroless or Electrolytic process.

Secondly, we are much concerned about RoHS environment. So can you give suggestion what process we should follow, Electroless or Electrolytic?

Thanks
Mihir

Mihir Rawal
- Sydney, NSW, Australia


January 16, 2012

A. Hi, Mihir.

"Electrodeposited" equals electrolytic, so QQ-N-290A describes electrolytic nickel plating; but it is cancelled, so please obtain AMSQQN290 [link by ed. to spec at TechStreet].

Many suppliers have reformulated their electroless nickel processes to be free of cadmium and lead for RoHS compliance, but you should check. RoHS compliance may be required for your parts, and is advisable in any case, but is not a driver in deciding whether to use electrodeposited vs. electroless nickel.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



March 21, 2012

Q. Which nickel process gives the best solderability? How best to reduce/eliminate peeling on Al 3003? We see this a lot when using chloride based fluxes.

phil hughes
- Santa Clara California USA


A. Hi Phil. Sulphamate nickel plating needs no sulfur-based brighteners so it has less heat sensitivity than other electrolytic nickel plating. Electrolytic nickel is probably easier to activate for soldering than most electroless nickels, but Nickel-Boron electroless nickel plating can be soldered with RMA (rosin mildly activated fluxes).

Plating on aluminum involves an "immersion plating" of zinc from a zincate bath; this is usually the weak link in adhesion. We have dozens of threads on the subject if you put "plating on aluminum" into the search engine near the top of the page.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



sidebar May 8, 2012

Q. I read that nickel plating is used for a basis for chrome plating and comprises 2 layers: semi-bright and bright. What are typical nickel plating thicknesses needed for exterior application corrosion resistance?

Tom Ward
Holland, Michigan


A. Hi Tom. 25 microns for general outdoor use, 30 microns minimum for automotive, 35 microns for long-term automotive use. The semi-bright layer should compose 60 to 75% of the thickness, and micro-cracked or micro-porous chrome plating should be used. Per ASTM B456 [link by ed. to spec at TechStreet].

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



May 29, 2012 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Environment: Part is exposed to tap water, chlorine, bleach and detergent.
Currently using a Dull Nickel Electroplate and it is rusting very early in life.
Would High Phosphorous Electroless Nickel plating offer a significantly increased corrosion resistance? What is the average salt spray resistance?

Chris V [last name deleted for privacy by Editor]
- Louisville, Kentucky


May 31, 2012

A. Not many affordable platings will stand up to that environment very long.

For electro nickel, thickness is very important; the more the better. For Electroless Nickel a high phosphorous will work better than a middle one. Boron EN will frequently do better yet. Here again, thickness is critical. With a problem, I would not use any less than 0.0015 inches (1.5 mils).

Consider putting a high phosphorous EN over a good base coat of electro nickel for even better results.

It will probably be cheaper to go to the part made out of 316 stainless or an even more exotic stainless.

James Watts
- Navarre, Florida



August 17, 2012

Q. Hi,
How can analysis differentiate the Electroless nickel and Electrolytic electrolytic nickel plating? Is there any physical or chemical or instrumental testing methodology available? Please explain.

Divahar S

Divahar Selvaraj
- India


August 21, 2012

A. Hi Divahar,

Dependent on the technology used, electroless nickel coatings will contain either phosphorus or boron, electrolytic nickel coatings tend to contain small amounts of sulphur. A suitably sensitive X-Ray Fluorescence (XRF) will be able to tell the difference by detecting the non-metallic component. Also Scanning Electron Microscope (SEM) with an EDX attachment would do the same job.

Brian Terry
aerospace - Yeovil, Somerset, United Kingdom



January 27, 2013

Q. Is the film produced by electroless nickel plating catalytic in nature ? (i.e., it can work as a catalyst in combustion reaction?)

Harsiddha Dave
B.V.M. Eng. College - VALLAH VIDYANAGAR, GUJARAT, INDIA


January 29, 2013

A. Hi Dave. When we in the plating industry say that electroless nickel is catalytic, we mean that the nickel plating catalyzes the reducing agent for continued deposition of more nickel from the plating solution; we are not talking about combustion. I know nothing about combustion engineering, but I have no reason to suspect that electroless nickel plating would catalyze more complete combustion.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



October 30, 2014

Q. Does the Electro Nickel plating process change the molecular structure of the base metal? (not Electroless)

Q. Does it heat the base metal at all?

Q. How well will it last in a mild caustic wash down situation?

Derek Liddington
- Nelson, New Zealand


December 2014

A. Hi Derek. Electrolytic nickel plating could possibly cause hydrogen embrittlement of high strength steel. And if a heavy layer were plated on a very thin object, the tensile stress of nickel plating could possibly compressively stress the object.

Nickel plating is done by immersion in an aqueous based bath at 140 °F, and the part could be slightly warmer, and might approach the boiling point of water earlier in the pretreatment process.

Nickel plating of reasonable thickness, so it is free of porosity and pitting, should stand up to a mild caustic wash down.

It would probably be better to describe your intended application, because that way readers might be able to warn you about potential issues rather than you having to try to imagine them. Another problem with abstract questions is that you may be concerned about the overall process whereas readers might respond in terms of just the one nickel plating step per se rather than the usual prep steps; another potential problem is that different substrates may involve different issues. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



January 10, 2016

Q. Hello, could anyone tell me when and why should I go for the electroless coating rather than the electrolytic? What will be the major difference in their end results?

Vimal Adzenhan
- Surrey, England


January 2016

A. Hi Vimal. If you give us a specific application & situation, I think people can answer you very directly which type of nickel plating would be best for that situation and why. In general, electroless nickel offers significantly greater corrosion resistance at significantly greater cost. There are many responses already posted on this thread by Michael Brewington, Guillermo Marrufo, Sara Michaeli, Frank Masetto, James Watts, and others which attempt to answer your question in general terms of corrosion resistance, consistency of thickness, hardness, magnetic effects, temperature resistance, speed of deposition, etc.

But there are many different types of electroless nickel plating, and many different types of electrolytic nickel plating -- and achieving a deep & thorough understanding of their peculiarities is the work of years, not a paragraph or two. Metal finishing consultants usually acquire several decades of experience before they presume to be able to accurately project applicability of a finish and its service life. The previously linked books by Mallory & Hajdu, and by Dennis & Such would be a good intro though. Good luck.

Regards,

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



September 16, 2017

Q. What will be the process sequence for Antique brass plating on mazak?
Presently we are doing copper + bright nickel + brass + black nickel (all are electrolytic), and antique finish by brushing the black nickel.
But rejection rate is huge; can we do electroless nickel instead of bright nickel?

Krishna Talekar
- Pune, Maharastra, India


December 7, 2017

A. Hi Krishna,
Where is your failure occurring? You state the reject rate is "huge". Is it due to the antique finish not being what you want once the black Ni is polished back? What would the bright electroless Ni be fixing? It seems, based on your post, you aren't satisfied with the imitation patina you end up with. If it isn't inconsistencies in the antiquing that is causing the rejects then what is?

chance dunstan
Chance Dunstan
Electroplating/Forming/Coating Manager
Placerville, California USA




February 20, 2018

Q.
Dear Sir/Madam

I want to plate Brass Material, and electrical conductivity is our consideration. So, in term of conductivity, which one is better, electrolytic or electroless Nickel Plating?

Thank you for your kind response.

Best regards,

Dallas Sitinjak
- Batam, Indonesia


February 2018

A. Hi Dallas, electrolytic nickel is better. For details please see Sjamp van Esch's excellent response on topic 18940. Good luck.

Regards,

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



Electroless Nickel isn't resisting bleach

November 9, 2018

Q. Hello. I've sourced components to be electroless nickel plated (high phosphorus) in an effort to improve corrosion resistance as compared to clear zinc in an environment with high humidity and periodic exposure to dilute chlorine bleach that is used for sanitizing purposes. The EN plated parts performed very well compared to clear zinc in salt fog testing however we're experiencing the complete opposite with daily misted exposure to a 50/50 mix of commercial chlorine bleach and water. This is not what I expected. Are there recommendations on where to start with root causing this or recommended alternatives that might perform better (not changing the substrate as I'm trying to avoid re-tooling). BTW, the substrate is low carbon steel. Thanks much!

Michael Coleman
Mechanical Engineer - Noblesville, Indiana US


November 15, 2018

A. Of course zinc with a clear chromate will not withstand repeated exposure to bleach.

I'd expect electroless nickel to do very much better, but that will depend to some extent on the surface preparation and EN thickness. In this aggressive environment, I'd suggest at least .001" thick, maybe more.

However if your standard is hundreds or thousands of exposures, then you're going to have to change material.

If plastic will work, then there are multiple choices - PVC, polypro, teflon, etc. There are metal alloys too.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg, South Carolina


November 2018

A. Hi Michael. The reason it's performing worse than zinc is that zinc is anodic to steel and preferentially corrodes, whereas nickel is cathodic to steel and -- once breached through a pinhole or porosity -- will accelerate the rusting.

As Jeff says, as a first step it must be thick enough to be completely free of pinholes and porosity.

And thanks for reminding our readers, through example, that salt fog testing should not be used for trying to compare the corrosion resistance of one finish to another.

Regards,

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


November 19, 2018

Q. Thanks for the feedback Ted and Jeffrey. I'll likely pursue a heavier nickel deposition in parallel with analysis, maybe SEM, to see what might be going on at the grain level with porosity. Some further background that I didn't mention was that the components are being stripped of clear zinc plating prior to EN. I don't know if this might have an etching effect at the grain boundary that might increase porosity and make the parts more difficult to plate adequately.

I mention this because after EN plating over a fc-0205 powdered metal component its performance was substantially poorer in salt fog and as a result will follow a different protocol for that component. Porosity is always a concern with plating powdered metal components needing corrosion resistance that are not either resin impregnated or copper infiltrated. Have anyone experienced issues as a direct result of the stripping process? The stripping process is acidic but other than that I don't know the specifics.

Another option I'm looking at is zinc-nickel. I've seen impressive salt fog results compared to clear zinc and zinc dichromate (the hex chrome component is driving obsolescence here). Testing is just getting underway with sodium hypochlorite exposure. Any feedback with zinc-nickel / chlorine bleach corrosion exposure would be greatly appreciated.

Thanks! This is a great resource!

Michael Coleman [returning]
- Noblesville, Indiana, USA



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