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Nickel plating / striking on stainless steel

+++++

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


Electrodeposition -- The Materials Science of Coatings and Substrates

+++++

A. Hi E.J. Yes, stainless steel definitely requires a preplate sequence which includes a nickel strike. The very best treatment of that subject is in Jack Dini's book, "Electrodeposition ..." =>

Yes, 30% is a ludicrously high reject rate; but it is believable, because if a plating process is done wrong, there is no upper limit on the percentage of rejects.

I'm sure there are shops right in the Kansas City area which can deliver a 99.9%+ pass rate on your parts tomorrow morning; I don't know how you manage to afford for your parts to be a learning experience for a plating shop 12,000 miles away which is making excuses for their incompetence :-)

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



+++++

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

V. Ranga Bhuvana Balaji
- India


+++++

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


+++++

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


+++++

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


+++++

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



++++++

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

Paulina Natera
- Westlake Village, California


++++++

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

adv.
Metalx [a finishing.com supporting advertiser] can probably help you.

Good luck.

Ted Mooney, finishing.com
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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,

Ted Mooney, finishing.com
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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,

Ted Mooney, finishing.com
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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,

Ted Mooney, finishing.com
Teds signature
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


Electrodeposition -- The Materials Science of Coatings and Substrates

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,

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


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,

Ted Mooney, finishing.com
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


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,

Ted Mooney, finishing.com
Teds signature
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


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 Aluminum How-To / Aluminio El Como



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
Popat Patel
    Howard Finishing
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,

Ted Mooney, finishing.com
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



December 11, 2014 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I have a print for a metal stamping that I need to purchase. The material calls for .25 MM stainless steel with nickel plating OR 0.10" CRS with bright tin plating. My question is, will these two types of materials/finishes, give the same performance? And, why would you need to plate stainless steel? Is that accurate? Thanks.

Lee Smith
buyer - Rolling Meadows, Illinois, USA


February 2015

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,

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



September 12, 2015

Q. I have been trying to electroplate my stainless steel Apple Watch, I did it using these steps and it didn't work; can anyone pick out where I have made a fault?
Step 1. Clean watch with alkaline solution, and run submerge test x2
Step 2. Clean with acid pickle and submerge
Step 3. Plate with nickel and submerge
Step 4. Plate with gold

When plated with gold it didn't show up. What could we have done wrong?

Rejaul Islam
- Lowestoft, Norfolk, England


September 2015

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,

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Pine Beach, New Jersey


September 16, 2015

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

Rejaul Islam [returning]
- Lowestoft, Norfolk, England


September 2015

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 won't be violated. Tell us about the bubbles you're seeing in the nickel plating tank and in the gold plating tank.

Regards,

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


October 23, 2015

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


thumbsup2Hi 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,

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Ted Mooney, P.E. RET
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December 7, 2015

Q. I read one of your previous posts recommending Woods Nickel strike as best for stainless steel. You mentioned that the nickel concentration should be monitored with 90 g/l as the upper limit. What happens above 90 g/l?

Suzanne M Ingalls
- Anoka Minnesota


December 2015

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,

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Ted Mooney, P.E. RET
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Purpose for nickel plating stainless steel in electrical applications

March 21, 2016

Q. I'm investigating an issue we are having with an 18-8 stainless steel screw (pan head, drilled spanner drive), which is being used as the contact for the positive terminal of a Lithium battery. Under shock and vibe, we've measured a voltage drop at the interface between the screw head and the battery terminal. We believe that the battery terminal is nickel plated stainless steel, however the screw is not plated. During our testing, we've found that if we nickel plate the SS screw, then the shock induced voltage drops no longer appear.

I would like to better understand why the screw needs to be nickel plated, in general, why is it necessary to Ni plate SS for electrical applications (assuming it IS necessary)? SS appears to be conductive enough, as we do not measure a voltage drop along the length of the screw, only at the interface to the battery. Assuming the Ni-SS "interface" within the battery terminal does not induce a voltage drop, why does the Ni-SS interface between the battery and the screw create a problem, such that I need a nickel-nickel interface there?

Thank you.

John Zelno
Electrical Engineer - Carlsbad, California, USA


March 2016

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,

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


March 21, 2016

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.

John Zelno
- Carlsbad, California, USA


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,

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



June 4, 2016
vacuum brazing didn't take

Q. SIR ! :) .
I TRIED TO VACUUM BRAZE Bv Ag 6-B (FILLER METAL) ONTO BASE METAL (SS 304 L) IN A VACUUM FURNACE. WHEN, AFTER THE PROCESS, WE TOOK OUT THE ASSEMBLY FROM FURNACE THE FILLER METAL (Bv Ag 6-B) BALLS-UP ALONGSIDE OF THE NOTCH TO BE BRAZED.
WE ARE THINKING OF CLEANING THE SURFACE PROPERLY (SURFACE PREPARATION) AND NICKEL PLATING THE SS 304 L BASE METAL.

I HAVE THE FOLLOWING QUESTIONS .
1) SHOULD I DO NICKEL PLATING FIRST OR SURFACE CLEANING FIRST ? .
2) WHAT MATERIAL AND PROCEDURE (FOR BOTH CHEMICAL AND MECHANICAL) SHOULD I USE FOR SURFACE CLEANING ? .
3) AFTER HOW MANY DAYS AFTER SURFACE CLEANING WILL THE BASE METAL (SS 304 L) REMAIN VALID FOR NICKEL PLATING ? .
4) WHAT IS THE EXACT LINEAR PROCEDURE FOR NICKEL PLATING ON SS 304 L - I MEAN THAT WHETHER WE SHOULD DO (WOODS NICKEL STRIKE FIRST AND THEN THE SUBSEQUENT NICKEL PLATING PROCEDURE) OR WHAT SHOULD WE DO IN YOUR OPINION ! .
5) HOW MUCH TIME AFTER NICKEL PLATING IS THE ASSEMBLY (SS 304 L + FILLER METAL) VALID FOR BRAZING - MEANS FOR HOW MUCH TIME AFTER PLATING CAN I DO BRAZING?
6) WHAT EXACTLY IS WOOD'S NICKEL STRIKE - IS IT AN INITIATION PROCESS FOR NICKEL PLATING?
7) WHAT IS Ni flash ? .

PLEASE ANSWER THESE QUESTIONS IN NUMBER SERIAL-WISE.
I WILL BE VERY MUCH OBLIGED AND THANKFUL TO YOU :)
THANKS IN ADVANCE .
WAITING FOR REPLY :) .

MUHAMMAD UMAIR TARIQ
- KARACHI, SINDH, PAKISTAN.


June 2016

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,

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


June 27, 2016

Q. SIR, I HAVE NICKEL PLATED MY STAINLEES 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?

MUHAMMAD UMAIR TARIQ [returning]
STUDENT . - KARACHI , SINDH , PAKISTAN .


June 2016

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

Regards,

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

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