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topic 28851

Process of Zinc-Nickel Plating


(2004)

Q. Sir,
We want to know about the process of Zinc-Nickel Plating. Can you please give us the process. Waiting for your reply at the earliest.

R.Ramarao.yalamanchi
plating shop - Hyderabad, AP, India


(2004)

A. Zinc/nickel alloy plating formula:

zinc chloride 130 gm
nickel chloride 130 gm
potassium chloride 230 gm
pH 5-6,temp.24-30 °C
separate zinc and nickel anodes.

Good luck!

Goran Budija
- Zagreb, Croatia


Electrodeposition of Alloys
by Abner Brenner

(2004)

A. Hi, Ramarao. Zinc-nickel plating deposits are made of zinc with a few percent of nickel in it (maybe about 6%). The idea is that this plating still offers sacrificial protection to steel like zinc plating does, but it does not corrode as quickly as zinc, and thereby provides substantially more corrosion resistance than an equivalent thickness of zinc electroplating. It is available as either an acid or an alkaline proprietary process offered by several suppliers in your area.

Although Goran is kind enough to offer a formulation, and although the process is discussed in Brenner, =>
... the robust electrodeposition of alloys like this requires specialized chemistry, and plating shops generally do not attempt to formulate such processes themselves. It is one thing to plate one small item in a laboratory from a generic formula, but quite another to do zinc-nickel plating in a production environment. Good luck.

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


(2004)

A. Mr Rama Rao Yellamanchi

Namaskaramandi.

Zinc Nickel Plating is used for automotive components which are exposed to higher temperatures as found in engine components where other alloys such as Zinc Iron fail easily or Zinc Cobalt does not withstand the tempering caused by engine temperatures.

Zinc Nickel stands Salt Spray 500 hours to white rust and more up to 1000 Hours to red rust with the right passivate.

Processes to plate Zinc Nickel are available within India. Alkaline processes are preferred over acid systems due to the superior distribution and even alloy content all over the component. Cosmetic brightness is possible .

You will need a lined tank, a filter 4-5 times/hr bath capacity, rectifier 6 volts, cathode movement,and a good pretreatment line as if you were doing Nickel. The Passivates are not the common ones used for regular zinc. All colors are possible.

Lastly Zinc Nickel costs 5 to 7 times that of regular zinc, micron for micron over a unit area.

Regards,

asif_nurie
Asif Nurie
- New Delhi, India

With deep regret we
sadly advise that
Asif passed away
on Jan 24, 2016



June 24, 2012

A. Agree with the three previous responses. Use the low pH version of Zn-Ni only if you need shorter dwell times in the plating bath or more ductility.

randy_lalande
Randy Lalande
- Hitchcock, Texas



E-coat is blistering on zinc-nickel plated parts

July 25, 2012

Q. Hi, I have a part that has zinc-nickel plating on it. We have an 11 stage immersion pretreat/e-coat system. I ran these parts thru our system in plant water and RO water (rinses only) I did not run them thru our alkaline cleaners because of removing the plating. So I just rinsed the parts and coated them with an epoxy e-coat. When the parts came out of our cure oven set at 375 °F for 45 min. to an hour they had small like popping (BBs) all over the part. I am wondering if the plating was breaking down because of the oven temp. or if there was some contamination on the plated part that caused this. I also had different part that had a cadmium plating on it, ran it the same way thru our system and had the same look to it. Any ideas what may have caused this? Need help. Thanks

Ken Cundy
- Mayville, Wisconsin, USA


July 26, 2012

A. Hi Ken.

Two things to do immediately are: 1. Put some plated parts in that oven or another oven for 45 minutes at 375 °F to see if the temperature alone causes the plating to blister.
2. Pop a few of those BB-sized blisters to see what is on the underside of the blister, and on the part underneath the blister to determine what is separating from what. First guess is the plating is separating from the substrate. Some things to consider are that the plating ought to be able to withstand this temperature, and that a bake is often used as a QA test to try to make parts blister early on, rather than blister later. I suspect that the parts are not clean enough.

Regards,

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



January 31, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Dear sir, please give me the formula of zinc nickel bath and others parameters. Thanks and regards.

Muhammad Amir
- Karachi, Pakistan


January 31, 2013

A. Hi Muhammad. We searched the site for you and appended your inquiry to a thread which we think answers it, but please post again if you have remaining questions.

Regards,

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


Q.

Dear sir, please give me the chemical composition of zinc nickel bath and others parameters. I use acid zinc additive of above plating. Thanks and regards.

Muhammad Amir
- Karachi Pakistan


February 24, 2013
A. Hi Muhammad. Goran and Asif already answered this question, so I'm not understanding the re-posting. Could you please try your best to frame your question in terms of the answers already offered so we understand in what way the answers were inadequate for you? Thanks!

Regards,

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



Zinc-nickel plating on 17-4 parts takes too long and blisters

February 5, 2013

Q. I have a Zinc Nickel line that does mainly Aluminum Bronze and 17-4 parts (aerospace). The Aluminum Bronze parts have no issues with adhesion and plating thickness. The 17-4 parts take twice as long to plate and then at post bake they start to flake or blister. Ideas?

Craig Hutchins
- Fort Worth, Texas, USA


February 12, 2013

A. Hi Craig,

Have you always had a problem with adhesion on 17-4PH steels, or is this something that has developed over time?

My initial thought was that the activation of the steel is insufficient to give good adhesion, but it is difficult to tell with the limited information that you have provided.

If this is a problem that has built up over time I wonder if you have had a build up of copper in the tank from the Aluminum Bronze and that this is depositing on the surface of the steel, causing problems.

Brian Terry
aerospace - Yeovil, Somerset, United Kingdom


October 7, 2013

A. Hi
Craig Hutchins

To avoid problems of blisters you need a nickel strike before Zn/Ni plating for SS material ( 17-4, 15,5), it is recommended for 52100 material (high carbon) also.

Good luck!

Eduardo Lorona
- Tecate, BC, Mexico



Interpreting thickness and salt spray specifications for zinc-nickel plating

March 21, 2013

Q. For zinc nickel plating what should be the correct criteria to determine the correct plating thickness? The spec. is 8 microns minimum. The process is rack plating.

My current supplier is taking 3 readings from the part and reporting an average of 12.8 microns; but from these 3 readings one of the readings is below the 8 microns due to the geometry of the part and variation of the thickness. Some areas are as low as 5 microns but the highest areas are 14 microns. Is this a correct criteria to determine the part meets the minimum thickness required of 8 microns or any point inspected should be above the minimum required?

The position of my supplier is that if the part is plated to achieve the minimum of 8 microns in the lower value areas the areas where more plating is deposited might go too high to 16 / 18 microns and create a chip / flaking issue.

Also the SST requirement is 480 hours salt spray for no rust. The parts are showing slight red rust at 480 hours. Should this be considered as a failure or pass?

Thanks for your help!

Ebe Salinas
- San Antonio, Texas USA


March 22, 2013

A. Thanks for an interesting one, Abe :-)

First, if your spec is 8 microns minimum, that's what it says and that's what it means, and parts with 5 micron thickness are not meeting it (usually though, a spec will call for the minimum thickness to apply only to surfaces that can be touched by a 3/4" diameter ball). Of course, that doesn't mean that your plater is necessarily wrong about the parts chipping or flaking if they go to 8 microns minimum :-)

If you are the end customer, you get to decide how thick is thick enough, and how many salt spray hours is enough. If you are happy with the parts and are having no problems in the field, I see nothing wrong with reducing the spec to 5 microns minimum and salt spray hours to 432 hours rather than 480 hours in lieu of developing a whole new process. But if you are a subcontractor yourself, parts that measure 5 microns do not meet an 8 micron spec, and parts that show red rust in 480 hours do not pass a 480 hour test. Good luck.

Regards,

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



May 16, 2013

Q. I have a current assembly with one material type 304 stainless steel and the other is 1008-1010 low carbon steel plated with zinc nickel chromate plus topcoat 8 µm. The assembly needs to pass 336 hours of salt spray, but can only achieve 50% of the required hours. I have attempted to have the 304 stainless steel nickel struck and then plated with zinc nickel chromate, but this did not improve the salt spray performance. I can change plating on the low carbon steel material, but the costs need to be similar to the current plating. Any suggestions on options for either component as far as plating that could offer 336 hours of salt spray performance?

M Gerken
Product Designer - Toledo, Ohio, USA


May 22, 2013

A. Dear Mr. Gerken,

First of all, you should put ONLY THE ZINC-NICKEL PART in salt spray and see the results to compare. If the results are good (more than, I say, 336 without white rust is fair), you have problems only with the assembly:

If the red rust appears in the contact surface or around it, we can think of galvanic corrosion (although you considered that when you zinc-nickel plated the SS304 part) or stress corrosion (if the parts are clamped or bent when assembled).

If it is the first one, you can try using a non-conductive lacquer or topcoat (if the one you are using is conductive) over the zinc-nickel part. This can prevent galvanic effects.

If it is accelerated corrosion by stress the problem, you can try some other chromate conversion coating, there are many vendors, and some top products can withstand up to 600 hours to white rust in salt spray (ASTM B117 [link by ed. to spec at TechStreet] ) for only-zinc-nickel-parts. Assemblies are a world apart.

AND... If you must, or want, to reduce costs and maintain corrosion resistance, you should try some organometallic coating on the low-carbon steel part. These products are conductive, compatible with stainless, corrosion resistance up to 1000 hours in salt spray, and the costs are, I think, lower than alkaline zinc nickel + topcoat. See for yourself!

Regards and good luck!

Daniel Montanes
- Canuelas, Buenos Aires, Argentina



May 22, 2013

Q. Our supplier plated Zn-Ni with the average thickness of about 14.1 micron with 13.6% nickel. As per our customer requirement, the part should withstand 720 hours to red rust. But, we checked, the part got white rust at 240 hours and red rust at 552 hours. What is the reason to get rust before 720 hours.

Manikandan Arumugam
- Bangalore,Karnataka,India


May 22, 2013

A. Hi Manikandan. 552 hours is not horrible, and not cause for embarrassment, so communication is key.

Try to find out from your customer where this spec came from. If other plating shops are achieving it on these parts for your customer, you probably need to as well. But sometimes specs just come from a designer reading sales pap and not realizing that the highest salt spray hours come only on ideal parts. Or using the salt spray hours s/he previously obtained on a totally different part. So it may simply be that 720 hours isn't reasonable on this particular part.

Regards,

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


May 24, 2013

Q. Hi Ted,
Thanks for your valuable answer. The same part from other plating shop is achieving 720 hours of SST as per our customer spec. If you give related answer for my query in finishing.com, I feel happy. Thanks a lot.

Manikandan Arumugam
- Bangalore, Karnataka, India


May 30, 2013

A. Hi again. As I said, 552 hours is not an embarrassing number, so it's hard to tell precisely why one shop got this while another has managed 720. But it seems that it can only be four possible things: they weren't tested in the same cabinet, or their chromate is better (which I tend to doubt), or their plating is either thicker than the minimum or more evenly distributed, or the composition of their alloy is slightly more corrosion resistant (less zinc).

Of these things, after assuring consistent testing, the easiest fix would seem to be to slightly increase the thickness of the plating if the customer does not object. Good luck.

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


May 31, 2013

A. Hello Manikandan,

I think that 14 microns of zinc-nickel (13% Ni is a really good alloy) should not show red rust in 500 hours of salt spray. Therefore, I think you should look for spots where the zinc-nickel is not 14 microns thick, and tell your supplier to achieve a minimum of 5 microns (or what it says in the spec you have) everywhere in the part to reach 720 hours of salt spray.

It is important to know (for me, at least) if it is a barrel-plated or rack-plated part. Barrel-plated parts have a more leveled thickness than rack parts, as the last ones don't move in the process.

As Ted mentions, the part is not achieving the corrosion resistance as spec, but it is not "horrible"! Your supplier must improve in leveling thickness (in my opinion, 14 microns even without conversion coating must last more than 400 hours) and maybe add some sealer over the conversion coating to get the white rust above 300 hours.

Hope you can solve this issue! Regards,

Daniel Montanes
- Canuelas, Buenos Aires, Argentina


June 2, 2013

thumbs up signGood point, Daniel. A sealer over the chromate may be the difference.

Regards,

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



Graphite Contaminating Zn-Ni Plating Baths

October 5, 2013

Q. Hi,

We are facing problems in plating of Hot Forged Components. The manufacturer uses Graphite as a lubricant during manufacturing of components.

Hot forged parts are porous in a microscopic level and graphite gets embedded within the component during the forging process.

The graphite does not get dislodged during Hot Soak Process and comes out only during Anodic cleaning process.

A layer of graphite starts to float on the bath which will carry over to subsequent baths as well.

Presence of graphite causes black patches on plated parts as well as it causes material erosion in some cases.

Please provide a solution for this problem.

Thank You

Roopak

Roopak Nayak
- Bangalore, Karnataka, India



Base Metal Erosion due to Zn-Ni electroplating

October 7, 2013

Q. We have a hot forged and controlled cooled micro alloyed steel component.

Only 30% of the surface is machined and remaining is as forged surface.

We are doing Zn-Ni (Non cyanide alkaline bath) electroplating on the component.

Base metal erosion is happening on the machined surface after the plating process.

erosion on Zn-Ni electroplating

Pre part is not having any such erosion and plating thickness and Ni % is ok on the eroded surface.

Forging process: We are using graphite based forging lubricant.

Plating Process: 2 X degreasing --> Anodic Degreasing --> Pickling --> Anodic Derusting --> Mild acid dip --> NaOH activation --> Zn-Ni electroplating --> DM water dip --> Iridescent passivation (High Co & low Cr3+) --> Dewatering Oil dip --> Oil dripping.
Plating is done in fully automated line with SCADA system.

Suggest us with the possible causes for the metal erosion defect.

Srinivasan Rajagopalan
- Bangalore, India


October 9, 2013

A. Hi Srin,
I have never seen erosion like that before. A few guesses:

I think that you are having an interaction of some of your chemicals on the pre plate steps. There are some strange combinations of chemicals that can become extremely aggressive. Think of aqua regia for example. Makeup chemicals are not terribly aggressive but together they can dissolve gold.
A touch of fluoride can make a world of difference in an anodic bath.

When you say alloyed steel, what alloy?

That said, I cannot think of any steel that you can activate with NaOH.

James Watts
- Navarre, Florida


September 2013

A. Hi Srinivasan. I think the part hit the anodes in one of the electrified tanks.

Regards,

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


October 15, 2013

Q. Dear Mr.James,

We are using graphite based die lubricant in forging of this component. Can this lead to this kind of defect if it is carried over to pre cleaning tanks like anodic?

Also If HCl is carried over through the pin holes and punctures in the rack insulation to anodic derusting tank after that, will it lead to this kind of defect?

Dear Mr.Mooney,

Apart from contact point in rack, we have supporting hook (306 stainless steel) near top and bottom of the part where we predominantly see this defect. This is not insulated, not supposed to touch the part but if touches will this kind of defect can happen?

erosion on Zn-Ni electroplating-2

Alloy of the base metal used is 38MnVS6 and it is controlled cooled immediately after forging to get the required hardness.

Please provide your respective suggestions.

Srinivasan Rajagopalan [returning]
- Bangalore, India


October 16, 2013

A. Hi, Srinivasan. I appreciate the rack sketch, but I'm not there and can't explain what may have happened. But I persist that this doesn't look like chemical attack to me -- it definitely looks like an electrical burn from a short circuit, with this area of the part touching an anodic or grounded item. Good luck.

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


December 31, 2014

A. Dear Srinivasan,

Zinc Nickel plating is one type of zinc alloy plating which is having high temperature & corrosion resistance among zinc alloy plating.

Zinc nickel ratio composition in zinc nickel alloy chemical (bath Solution) is Zn:Ni = 10:01 and normally bath parameters range is Zn (8 to 12 grams/litre) Ni (0.8 to 1.2 grams/liter which is controlled by AAS method or XRF method.)

zinc nickel plating ratio deposition in zinc nickel alloy plating is Zn (85 to 90 %) Ni (10 to 15%) which is high resistance.

While nickel percentage is more than 18% in deposition and zinc percentage is less than 82% in deposition, during environmental tests ( salt spray test) direct appear red rust. Salt spray corrosion resistance is less when nickel % is more than 18 in deposition.

Surya Narayana
Process Engineer - Tumkur, karnataka, INDIA.



Temperature for Zinc Nickel Plating bath

November 18, 2014

Q. Hi,

May I know the suitable temperature for zinc nickel solution to achieve best plating parts.

The higher the temperature will cause the higher the time to plate?

NORAZMA azema
production engineer - johor bahru , johor. malaysia


November 19, 2014

? Hello Norazma,
Are you plating with an acid or alkaline Zn - Ni solution?

Mark Baker
Process Engineer - Phoenix, Arizona USA


November 19, 2014

Q. Hi,

alkaline zinc-nickel.

norazma mukhtar [returning]
production engineer - johor bahru , johor. malaysia


December 4, 2014

A. Hello Norazma,
Most alkaline Zn - Ni baths run at about 25 °C (77 °F). The best bet is to consult the Tech Data Sheet for the bath from your Zn - Ni supplier. If you don't have one, ask your bath supplier. Proprietary plating solutions dictate temperature ranges. As far as the second part of your question, higher temps would normally speed up the deposition process. Are you having trouble maintaining the bath temp? Keep in mind higher bath temps will have an effect on the final finish cosmetics. Good solution movement, cathode bar agitation, and maintaining tight bath temp ranges is the key to consistent plating.

Mark Baker
Process Engineer - Phoenix, Arizona USA


November 17, 2014

Q. Hi
I'm Venugopal working in R&D department. I need the details of how zinc nickel forms on steel component? What is chemical formula of zinc nickel plating? Normally in zinc nickel coating zinc percent is higher -- then why white rust is not forming as in zinc plating?

Regards

VENUGOPAL ALAGARSAMY
- Chennai, India



May 16, 2015

Q. My problem is that there are no suppliers of the chemical "RODIP ZNA YELLOW" in my region; please help.

RAO FARMAN ALI
- islamabad pakistan


May 2015

A. Hi Rao. That product is a powdered chromate formulation from Atotech for bronze iridescent chromating on zinc-nickel plating. Other suppliers such as Macdermid Inc. [a finishing.com supporting advertiser] and Enthone presumably can offer equivalent products if access to Atotech products is not possible in your region. Good luck.

Regards,

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



Adhesion Problem with Zinc Nickel on Stainless Steel

May 26, 2015

Q. Hello everyone.

We are having problem with adhesion with Alkaline Zinc Nickel on hardened stainless steel. The problems occur on hardened martensitic stainless steel. For Copper or Al or Be alloys, plating works wonderfully, also on 4130 steel. Adhesion is not a problem on those base metals.
We also CAD plate the stainless steel, and we do it well. The only problems we have on stainless steel is with ZnNi. I have read the other inquiries on here, but have not seen a response from the original question starter with results.

I think, like many, that it is a surface pretreatment issue with this, but why would Cadmium plate adhere well and ZnNi won't?

We have tried different activating methods, lower amp and longer nickel strike, different nickel strike rations, NiCl:HCl 2:1, 1:1, and still the same.

The method i use to test the pieces is by getting around 5-7 pieces and shake them in my hand. They hit each other, and the plating comes off. If i do this with ZnNi plated on bronze alloys, the plating will not come off(peel off.) If i do this test with cadmium plated stainless steel, the plating will not come off either. Only on ZnNi plated stainless steel.

I have recently tried a little coat of Electroless Nickel after my nickel strike, then plate ZnNi, and the plating still comes off. It comes off in a finer dust, but it is still coming off.

This has been problematic for us, we have done it in both acid and alkaline baths, and same results on stainless steel.

Can anyone that use to have similar problems help me out with this???

Btw, the composition for our S.S is :
Carbon 0.07 maximum
Manganese 1.00 maximum
Phosphorus 0.04 maximum
Sulfur 0.03 maximum
Silicon 1.00 maximum
Chromium 15.00 - 17.50
Nickel 3.00 - 5.00
Copper 3.00 - 5.00
Columbium plus Tantalum 0.15 - 0.45

Please help, is driving me nuts!

Somethings to look at: successfully remove passive oxide film on the stainless steel to be able to plate Ni strike followed by ZnNi. But HOW? have tried 5 minutes in 30 percent HCl, and it flaked off less, but still flaking/plating coming off.

Thanks!

Oscar Sanchez
Employee - San Diego, California


Electrodeposition -- The Materials Science of Coatings and Substrates

May 2015

A. Hi Oscar. I think it should be possible to determine whether the nickel strike layer is peeling from the stainless steel substrate, or the zinc-nickel plating is peeling from the nickel strike layer. The corrective action would differ based on where the problem originates.

If the nickel strike is not sticking, I suppose it's possible that the parts aren't really clean. Try to get a look at Dini's "Electrodeposition", which has a chapter on "Adhesion" with lots of good data on nickel striking of stainless steel =>

If the nickel strike is sticking, but the zinc-nickel plating doesn't stick to it (which seems to be what you are reporting) there may be too long a delay between the strike and the plating. The strike is a nickel-rich surface which rapidly passivates. Possibly the cadmium plating is better at dealing with this marginal passivation of the nickel strike. You may learn something from plating "stress tabs" in a Hull Cell. Good luck.

Regards,

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



Pitted zinc-nickel plating

March 9, 2016

Hello everyone again!

Our zinc-nickel treatment has some problems lately. We are doing some parts for automotive clients that are getting pitted after the zinc-nickel plating bath.

The raw materials of the parts (that we made) are 10B22 in both cases. The first one (hexagonal) is hardened and tempered 8.8 (27-29 HRC) and the second one (plastic thread) is cemented, quenched and tempered (530 HV in surface and around 40 HRC in core). This I explain is because of the low efficiency of the bath in the second case. We need to plate for around three hours to get a 10 micron layer.

Both parts are pickled in hydrochloric around 10% (1/3 diluted 32%), rinsed and dipped in caustic soda before the plating bath. Our plating bath is a barrel semi-automatic one, with 30 kg barrels. Our zinc-nickel plating bath is a proprietary formula alkaline one, 12-15% Nickel. Later, the parts are blue chromated and ready to go.

28851-1aThmb  28851-1bThmb  28851-1cThmb
Good parts, and two examples of bad parts.
Click pictures for high resolution photos.

We are experiencing this pitting for third time in the 6 years I am in this company, and we never got to know why.

I bring this to you, because many heads think better than one. Has someone seen anything like this?

Thank you in advance, and best regards!

Daniel

Daniel Montanes
- Caneulas, Buenos Aires, Argentina


March 10, 2016

? Good day Daniel.

I have been following this thread as I will soon be implementing the process.
I do not have any experience as yet with the process, but I am doing research.
My question to you is, "Both parts are pickled in hydrochloric around 10% (1/3 diluted 32%)".
I would believe this is a 33% HCl solution.
What are the process parameters for pre-dip?

Regards,

Eric Bogner, Lab. Tech
Aerotek Mfg. Ltd. - Whitby, Ontario, Canada


March 18, 2016

Q. Hello Eric!

You are right, it is a 33% HCl bath, but we chemists sure are complicated: As the "pure acid" is not 100% but 32%, a 1:3 dilution will be 10,7% HCl, but for all practical purposes it is correct to say it is a 33% HCl bath.

Pre-dip is as follows:
-HCl 25-40% 20 min (with wetting agent and Fe inhibitor)
-Rinse
-NaOH 30% 30 min (it doesn't have to be this amount of time, but it depends on how much time the parts are plating).

Then it goes right into the plating bath. We don't believe it is an acid pitting because of the way it appears: On the head and the point, always from the middle to the edges. We think it could be some noise in the electric circuit that could make the current flow the other way... We are trying to test it now, as it happened again today.

If we have more data I will be posting it on Monday or Tuesday. Thank you in advance!

Best regards,

Daniel Montanes
- Canuelas, Buenos Aires, Argentina


March 19, 2016

A. The localized attack to the ends of the parts could suggest something in the material. Is this limited to one coil/material of manufacture? I know it is the same material.

If you rule that out, I could be an End grain pitting/inter-granular attack. Is your acid inhibited? Are the pits visible prior to plating? Post acid activation? Inspect the barrels after every operation to help with trouble shooting.

DEHUC MYKYTCZUK
- Toronto, On, Canada



March 31, 2016

Q. Hi all. I have a question about zinc-nickel plating. We are making a part and have to send to our finisher for getting zinc-nickel plating. This part has two PEMs; if we use zinc plated PEMs, after plating the color of PEMs turn black. I do not know what is the reason? Material of PEMs, thickness of zinc on the PEMs, or washing time and composition before plating?

Thanks.

peyman basirian
quality engineer - vancouver, BC, Canada
  ^- Privately contact this inquirer -^



April 12, 2016

Q. We are facing problem in Alkaline Zinc Nickel Plating Self Tap screws M5 x 18 . Carbonitriding process with 340 HV hardness. Even after 3 Hours of Plating coating thickness found 2 - 4 Microns in the parts. Load Qty : 40 Kgs Current : 500 Amps.

Any suggestion to overcome this problem.

Geetha Muthuramalingam
- Tamil Nadu India



June 14, 2016

Q. Hi,
We are doing zinc nickel plating on alloy steel components. Some of these components have tubular shapes and cavities about 40 mm in dia and 50 mm deep. We are getting zero thickness in the inner side of these cavities and the salt spray fails within 120 -150 hrs. On the outside, the thickness achieved is around 25 - 30 micron and the salt spray test is also okay from the outside area only. Can you please suggest any remedy to achieve thickness at the inside area of these parts. Voltage = 4 - 6 V. Time = 30 minutes.

Yasir Khan
- Karachi, Pakistan



July 14, 2016

Q. Dear sir .
Please help me regarding acid zinc-nickel. I am starting acid zinc-nickel plating in barrel plating; I don't know what are the standard parameters of this bath, and some problems face me every day. After 2 barrel plating the fastener threads are not bright and if I am doing Hull Cell test then Hull panel LCD area is full dull. What should I do I don't understand. Please help me with standard bath parameters and maintenance of acid zinc-nickel bath.
Thanks sir .

amit awasthi
- mumbai , maharastra , india


A. Hi, Amit. The supplier you are purchasing your zinc-nickel plating process from will have a "technical data sheet" instructing you how to operate it. It's a fairly complex process because you don't just need the right thickness and brightness, you need to maintain the correct percentage of nickel in the deposit or it will not offer the proper corrosion resistance. Good luck.

Regards,

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



July 22, 2016

Q. We want to use Zn-Ni Electroplated coating for our clamps and thinking to get the 25 µm to 30 µm Zn-Ni electroplated coating thickness with 12 wt% of Nickel content. Does this thickness improve the corrosion resistance purposes or it's detrimental? Should we need to adhere to 8 µm to 14 µm coating thickness to achieve the optimal performance?

John Stacey
- Sydney, Australia


December 2016

A. Hi John. For standard zinc plating there is no doubt that 25 microns is better than 8 to 14. Standards like ASTM B633 [link by ed. to spec at TechStreet] call for 5 microns for mild exposure, 8 for moderate, 13 for severe, and 25 for very severe. To my knowledge 25-30 microns of zinc-nickel is not deleterious, but you might check with your supplier because there might possibly be difficulty with chromating, roughness, or something else they caution you about for their process at that thickness.

Regards,

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



December 9, 2016

Q. I am trying to deposit Zn-Ni on 4 inch x 2 inch CM steel sample using a chloride bath with pH 5.5-6.0. I am plating two samples simultaneously using a 15 L bath. I am seeing black and burnt coating at the bottom up to a height of nearly 1.5cm. Kindly suggest how to overcome. I am using a filtration system and the cathode movement is very slow.

Regards

Manju Srinivasan
- UP India


December 20, 2016

A. Hi Manju,

Please enlighten us with:

- Barrel or rack plating?
- Acid Zinc-Nickel: which nickel percentage (low or high)? Do you test in hull cell? What are your parameters (potassium chloride, metallic zinc, voltage, time, temperature)? Do you test for iron?

I think that we can help you if you can give us more information.

Best regards!

Daniel

Daniel Montanes
N FERRARIS S.A. - Canuelas, Buenos Aires, Argentina



January 13, 2017

Q. I AM STARTING THE ZINC NICKEL PLATING, PLEASE HELP ME.

GAGANDEEP SINGH
- PUNJAB,INDIA


January 2017

A. Hi Gagadeep. Your 10 words don't comprise a very realistic request. Please start with 3 or 4 paragraphs summarizing what you know and don't know about the subject, and hopefully we can start a back & forth and make some progress.

Regards,

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



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