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Nickel plating / striking on stainless steel

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Q. My supplier in Far East told me that stainless steel is very difficult to be coated with nickel. The stainless steel part we need to plate is SUS304 and is used in battery door as a charge contact. The supplier claimed that the failure rate of plating is about 30%, which is unbelievably high. I am wondering what is the best plating process for nickel plating stainless steel. Is it necessary to insert Nickel strike step?

Thanks in advance for the help.

E.J. Li
Consumer products - Kansas City, Missouri


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A. Hi E.J. Yes, stainless steel requires a preplate sequence including a nickel strike.

If a plating process is done wrong, there is no upper limit on the percentage of rejects, so 30 percent rejects is very believable if you choose to send your work to people who don't know what they are doing :-)

I'd bet there are shops right in the Kansas City area which can deliver a 99.9%+ pass rate tomorrow.
pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



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Q. Can you please tell me what is "Nickel strike"?

V. Ranga Bhuvana Balaji
- India


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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,

Ing. Gabriel Ramirez N
- Toluca, Mexico


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A. Wood's nickel is the most popular. It consists of a highly acidic, low efficiency, all chloride nickel solution prepared with 250 g/L nickel chloride, 250 mL/L conc. HCl, rest DI water. Operated at room temp, 20-100 a/sq-dm, anodes pure nickel.

Guillermo Marrufo
Monterrey, NL, Mexico


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A. If you have to ask this question, you really need a good reference book on plating.
A nickel strike is a very thin coat of a nickel that will stick to stainless that has been properly cleaned and activated. Typically a Wood's Strike is used. It is a very high chloride bath at a very low pH that plates very slowly and is extremely highly compressive stressed, so you only want enough of a coat to barely give a "color".

James Watts
- Navarre, Florida


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A. Are you rack plating or barrel plating? If you are barrel plating be sure to have good pump agitation as well as a slightly higher HCl concentration. Stainless Steel is not as tricky as some would make it seem. Also try to remember that a Ni strike normally requires a higher current to strike parts. Consider covering surface of your bath with plastic balls, available from plating supply companies to reduce surface fumes. Good luck!

Regards,

Michael Null
- Methuen, Massachusetts



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Q. What happens to the rejects? Can the same steel be "cleaned" and re-plated?

Paulina Natera
- Westlake Village, California


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A. Hello, Paulina. It's not clear to me if you are following up on E.J.'s question, or if your situation is somewhat different. In general, nickel can be stripped from steel relatively easily, but not as easily from stainless steel because they are somewhat similar. Good luck.

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


October 3, 2009

Q. I understand Stainless Steel is a tricky material to plate with Nickel followed by Cadmium. Does surface preparation matter? E.g., which is better: sand-blasted surface or vibro-finished surface? And what time lapse permitted after above finishing and before plating ?

B Pramod
- Landewadi, INDIA


October 5, 2009

A. Hi, B. In electroplating, the adhesion is molecular, not based on mechanical "keying" as in painting. So either sand blasting or vibro-finishing can be used, depending on what you want the surface to look like.

If sandblasting is practical and convenient for your parts, it's ideal, but you still need the Wood's Nickel Strike before the nickel plating and cadmium plating.

The allowable time lapse depends on your handling and your intentions. For example, if you are going to immediately plate, sandblasting is the only prep you may need before the nickel strike. But if the parts are going to hang around for a couple of days, you will need to alkaline clean them and acid activate them immediately before the nickel strike. The best approach is surely to plate immediately after blasting. Good luck.

Regards,

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


July 7, 2011

Q. SIR, PLATING PEELS OFF WHEN WE DO NICKEL ON SS AND THIS LAYER IS FOLLOWED BY 2N FLASH GOLD

MANNU SHARMA
- solan h.p. india


July 7, 2011

A. Hi, Mannu. When you say nickel on stainless, it isn't clear that you are applying a Wood's Nickel Strike as explained above. Please give full composition and plating conditions of the nickel strike you are trying to apply. Thanks! Jack Dini's "Electrodeposition" has an excellent chapter labeled 'Adhesion' which gives adhesion values for various approaches to nickel striking stainless steel. Please check it out. Good luck.

Regards,

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

January 24, 2012

Q. Sir
We are doing nickel strike on the component and then bright nickel and then 2N flash gold. But after complete process gold plating peels off. Base material is ss.

MANNU SHARMA [returning]
- solan h.p. india


January 24, 2012

A. Hi again.

If it's the gold plating peeling off of the nickel plating, rather than all of the plating peeling off, then probably you are either waiting too long to begin the gold plating (you should quickly rinse the nickel, then immediately go into the gold plating bath) or there is an excess of brighteners in the bright nickel plating. Good luck.

Regards,

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


January 26, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hello, I have a fundamental questions: why put nickel on stainless steel? (Only for appearance?). Is there somewhere a chart with values of nickel adhesion on stainless steel obtained in a test on flat surface with a specific device like nano-indenter? What value should it be?

I would like to ask if you could recommend me some basic/fundamental source (article, book) where I could find something solid about nickel plating adhesion on stainless steel (values). I read a chapter Jack Dini's "Electrodeposition" but it does not explain the basics like why put nickel on stainless steel. Could you recommend something?

Jurek Cieslik
- Lodz, Poland

January 30, 2013

A. Hi Jurek. We appended your inquiry to a thread which implies the answer: Electroplating must be done on bare metal (not tarnish or oxides) for proper adhesion, but stainless steel instantly forms a passive oxide on its surface which prevents that proper adhesion. The most popular way of addressing that problem is to start with a Wood's nickel strike or other nickel strike. Being highly acidic, it dissolves the oxide, while simultaneously applying a thin layer of nickel plating to the bare stainless steel. The book by Jack Dini that you referenced =>
is excellent once you understand that the chapter in question is titled "Adhesion", and it's all about the best procedures for getting good adhesion onto stainless steel with a nickel strike. Good luck.

Regards,

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

Electrodeposition -- The Materials Science of Coatings and Substrates


April 4, 2013

Q. Hello,

why put nickel coating on stainless steel? Better corrosion resistance? Better adhesion of solder to nickel than to steel? So why do it? Not how, this I already know.

Best regards,

Jurek Cieslik [returning]
- Lodz, Poland


April 4, 2013

A. Hi Jurek. The short answer is, of course, that stainless steel is nickel plated when the surface properties of nickel are better suited for the application in question. If you search this site for "nickel plating stainless", you will see a number of applications discussed. For example, nickel will have much better surface conductivity and will be a much better electrical contact than stainless steel; also, as you suggest, it will be more readily solderable; it may be more corrosion resistant in certain environments. Also, the nickel plating may be necessary before other types of plating like gold plating can be done on the stainless steel. But it's not possible to list or predict every possible application where the surface properties of nickel would be more desirable than those of stainless steel. Good luck.

Regards,

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


March 14, 2013

Q. Hello, we are having problems with adhesion on stainless steel. We run a Zinc Nickel bath with no brighteners and nickel strike all stainless steel parts before plating. What are the components of a good nickel strike bath for a barrel process? Please include volts, amps, and processing time. Thank you.

Asa Sanders
- North Richland Hills, Texas USA


March 15, 2013

A. Hi Asa,

You can find formulations for nickel strike in any decent text book on plating, such as the "Electroplating Engineering Handbook" [link is to product info at Amazon], "The Canning Handbook" style= [link is to info about book at Amazon] and the Metal Finishing Guidebook. These include formulations, temperatures, voltages, etc.

It sounds like you have to go back a bit further than the nickel strike to start your investigation.

Firstly look at your degreasing and cleaning process, are you getting a water-break free surface? Yes - good, No - time to investigate your cleaning process.

Secondly look at your etching process prior to nickel strike. Are you using one? For stainless steels I would highly recommend it as the steel will have a naturally passive layer on it that needs removing before plating.

Next it is important that you do not delay from nickel strike to the plating tank. From nickel strike you need to rinse and be in the Zn/Ni tank within 2 minutes. Any longer and you'll end up with a passive nickel strike.

That should get you started down the right road to a robust process.

Brian Terry
aerospace - Yeovil, Somerset, United Kingdom

March 15, 2013

Q. We are activating the parts before nickel strike in HCl for 2-5 minutes. We have already looked at our degreasing process and are good. We also get the parts into the strike within 2 minutes. We are only getting .8 to 3.2 microinches of nickel on the parts in 8 - 10 minutes. Is this enough for our barrel process?

Thank you.

Asa Sanders [returning]
- North Richland Hills, Texas, USA


March 20, 2013

A. Hi Asa,

A couple more questions:

Do you know if the plating is failing between the base materials and the nickel strike, or is it failing between the nickel strike and the Zn/Ni plating?

If you find that it is failing between the base material and the nickel strike it indicates either a problem with the nickel strike or the pre-cleaning.

If it is failing between the nickel strike and the plating then it may be the nickel layer going passive or you may have a problem with the Zn/Ni plating process.

The nickel strike is designed to give a very thin, adhesion promoting coating on the surface of the base material. I must admit I have never checked the thickness of the nickel strike, but it would certainly be less than a micron, so I would guess the thickness is probably in the right ballpark.

If the nickel strike is acting unpredictably it could be due to a build up of tramp metals in the tank (usually copper and/or iron). You can do one of two things about that, either dummy out the metals (large surface area cathode, low current density) or dump and re-make the tank.

Brian Terry
aerospace - Yeovil, Somerset, United Kingdom

March 21, 2013

thumbsup2We actually found the problem when we dumped the tank, their was a clamp at the bottom and had corroded away depositing iron to the metal. I thank you for all your help, it was much needed.

Asa Sanders [returning]
- North Richland Hills, Texas, USA


July 25, 2013

Q. We have been trying to do nickel strike on stainless steel boxes . . .

We have done strike nickel on other materials and we have been successful but we have failed to do strike nickel on these boxes. We are using degreasers properly, the rectifier is set at 8 volts and the boxes are put into the chloride tank for at least 4 minutes but the minute we remove it the box is a little black and the nickel is not catching the box. I hope you could help me with this.

Best Regards,

Robert Placid
- Dubai, UAE


July 26, 2013

A. The quality of the response is normally directly related to the quality of the question. You left out everything of importance. What is your strike chemistry. Have you checked for tramp metals in solution. What are your anodes. Are the bags clean. What is the parent metal, not just SS. What is your agitation. What is your anode to cathode ratio? Tank temp. Exact pre plate cycle (all of it)

James Watts
- Navarre, Florida


Coating inside a channel

September 29, 2013

Q. Hello,

I have a metal part with a channel inside (2 mm diameter of the channel). I wonder if the Ni coating would be or could be thinner inside this channel?

Another question is if the coating could be too thick? Does the higher thickness influence adversely the adhesion of a coating?

Best regards,
Jurek

Jurek Cieslik
- Lodz, Poland
  ^- Privately contact this inquirer -^


October 2, 2013

A. Hi Jurek. The nickel plating deposits in proportion to the current flowing to the particular area (see Faraday's Law of Electrodeposition). And the current flows in accordance with Ohm's Law (the greater the resistance, the lower the current flow). And the resistance between the anodes and points inside that 2 mm channel is very high compared to the resistance to points on the exterior. So little if any current will flow and little if any nickel will deposit.

Within reasonable limits of thickness the adhesion will not be determined by the thickness. Good luck.

Regards,

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


March 18, 2014

Q. I'm having trouble electroplating 304 stainless. It has been polished, then cleaned through a electro cleaner first on reverse polarity and then positive. Then rinsed, 10% sulfuric, rinsed, then Wood's nickel strike. Then directly into bright nickel, and chrome. Blisters 60% of the time. Peeling seems to be nickel strike off the stainless. Any ideas? Maybe a better activation process to activate the stainless?

Brett Troncale
- Santa Fe springs, California
contact


April 1, 2014

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

Daniel Hernandez Guerra
- Bucaramanga Santander Colombia


April 2, 2014

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.

Mark L Baker
Process Engineer - Malone, New York USA


April 4, 2014

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.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

Editor's note:    
   Mr. Probert is the
   author of


June 23, 2014

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).

Popat Patel
    plating shop
Roseville, Michigan



September 7, 2014

Q. Electrolyte which can be used in the electroplating of stainless steel and only nickel?
Why electroplating of stainless steel and nickel is not possible?

monika singh
- lucknow,u.p.,india


September 7, 2014

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

Regards,

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


September 13, 2014

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.

karthikeyan ponnusamy
- bangalore, Karnataka, India

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