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topic 51990

Parts turn black in Wood's Nickel Strike


A discussion started in 2009 and continuing through 2020 so far.
Adding your Q. / A. or Comment will restore it to the Current Topics page

April 24, 2009

Q. I am trying to plate 400 series stainless steel (I believe it is 416) with Electroless Nickel/Boron Nitride. The problem is it is smutting, and comes out of the Wood's nickel strike black.

1. Soak clean in a Sp degreaser Alkaline based
2. Rinse in DW
3. 50% HCl dip 1 min (the part never stops gassing)
4. Rinse in DW
5. Woods Nickel Strike (part starts to gas before power is connected)



What am I doing wrong?

Steve Johnson
plating shop employee - Johnson City, Tennessee, USA


April 27, 2009

A. A guess. The parts are anodic to the rack. What is your rack made of?
Is there any possibility that your Wood's Strike tank is electrically backwards?
What is the voltage at the part, not the rack?
If you are heavily gassing with 50% HCl, try a lesser percentage. 25 or 30% with a bit longer etch time should work just as well without the heavy gassing.

James Watts
- Navarre, Florida


April 30, 2009

A. Hi, Steve

What you have to do is turn on your rectifier before you dip in the parts

Karwai Liong
- Thailand


April 30, 2009

Q. The parts are connected anodic. The rack is copper and I am using 3 volts. I tried reducing the HCl to 20% and I still get some gassing not right away but after about 15 seconds

Someone has suggested avoiding the HCl and use a Citric acid then right into the EN bath avoiding the Woods Nickel Strike all together.

Steve Johnson [returning]
- Johnson City, Tennessee


April 30, 2009

A. Hi, Steve. I have never heard of citric acid for activation, onlt its opposite, passivation. If you can get access to a copy, Jack Dini's "Electrodeposition" has an outstanding chapter entitled "Adhesion" with quantitative data for adhesion onto stainless.

Regards,

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


April 30, 2009

A. If you really have the part anodic in the Woods strike (positive lead), then the parts will come out of the tank black or spotted and you will not have any nickel strike on them.
3 volts might be OK for a small load and give you the amps per sq ft that you are looking for, but otherwise it is a bit low. Anodically, it takes much less voltage to get an amperage than it does cathodically (forward).

Long ago, research on the best adhesion out of a normal Woods Strike, was at 90 amps per sq ft. Adhesion falls like a rock above about 100 ASF.

James Watts
- Navarre, Florida


May 2, 2009

Q. I am sorry I said it wrong. The parts are connected to the negative and the positive to the anode.

You are correct the part is only 40 sq inches

Is it possible to use a Citric acid to passivate the Stainless and avoid the woods nickel?

Steve Johnson [returning]
- Johnson City, Tennessee


May 7, 2009

A. James has described a probable good fix for the smut. A possibility could be that the parts aren't truly clean; strong acids working on oils will be a mess. It would be best to know exactly what stainless you are dealing with, and its work history. Passivating with citric acid is the last thing you'd want to do, Steve; yes it will probably eliminate the smut, but there's more to plating onto stainless: you'll have no adhesion.

What you need to do to plate stainless steel is clean it completely, acid treat it to bite off the passive outer layer, then retain an active surface for long enough to get plating going onto an active surface. That's what Wood's Nickel Strike does: simultaneously activate while getting a thin layer of fresh plating down.

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


simultaneous May 8, 2009

A. Copper is not a good rack material if it is bare. If it is covered with tape or plastisol or some other good masking, it is OK. I would still make the contact points out of brass or stainless or even titanium. If they are small, piano wire contacts might work.
We used home made racks out of brass rod for rack material in a great number of plating solutions. They were gradually eaten away, but at a rate that was slower than iron or copper.
It also carries a lot more current for a given size than SS or iron.
PS, You will use a lot less current, waste less plating solution, not pollute your tanks and have a lot less grief if you plastisol your racks (except the contact points).

Consider buying a good rack from one of the professional rack companies to get ideas for your own later racks. Most good rack companies will design a rack or modify a stock rack if they can see one of your parts and know how you are going to plate it IE: the complete process.

James Watts
- Navarre, Florida


May 11, 2009

A. Years ago I used to plate a lot of stainless steel components, including many different alloys. Occasionally we'd have an adhesion problem on a weld area, or the back of a part that had a weld on the front. Wood's nickel wouldn't touch it. We came up with a solution using potassium permanganate at close to boiling (I don't remember the concentration). This was merely a several minute "dip", not electrified, that solved the problem.

G. Brackett III
- Maine


May 12, 2009

! Permanganate is really a messy tank to operate. It works by oxidizing the carbon from the weld operation. It prepares the surface so that the follow on chemicals can work to activate the surface. It is in the standard practices manual for most airplane overhaul manuals.

James Watts
- Navarre, Florida


May 29, 2009

Hi Steve,

Try the following process .
I believe you doing over acid treatment an this is producing the smut.

1- Anodic Electrolytic Cleaning
2- Alkaline Periodic reverse Cleaning.(cyanide activation)
3- Acid dipping HCl 10% 30 sec (rinsing not required)*
4- Wood Nickel Strike 6-10 amp/dm2
5- Electroless Nickel

Remarks:
Nickel Strike do not deposit well on rough surfaces.
Nickel Strike must be chemically OK. 120 g/l NiCl2 + 240 ml/l HCl
Check the Anodes conditions and electrical contacts.

Gabriel Schonwald
Bnei Berak, Israel




How to remove Nitriding from Stainless so it can be Electroless Nickel plated


July 15, 2009

I am plating Stainless Steel that has been Nitrided. What type of pretreatment do I need to do before plating it with Electroless Nickel?

I know I need to remove the Nitride in order to use a Woods Nickel strike. If the Nitride is not removed first the Stainless will react in the HCL/DW and will turn Black in the Woods Nickel strike

Any way other then High pressure blasting?

Steve Johnson
plating employee - Johnson City, TN



To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)



Wood's Nickel is slightly black

December 23, 2011

Q. Sir,
I have a job of SS 430 automobile job. Customer needs electroless nickel plating.
I tried with Wood's Nickel: Nickel chloride 240 g/l and HCl 90 ml/l^3, A/Dm2.
After this the pieces get slightly black.
Please give the right procedure to do.

Thanks

Sakthivel T
- Coimbatore, Tamilnadu, India



A. Hi Sakthivel. Yes, Wood's Nickel Strike is already the correct approach, and your composition sounds workable, and close to that suggested by Don Baudrand. Your current density didn't come through in your e-mail, but as long as it's in the range that Don suggests, it ought to be okay.

I strongly suspect you are missing something, rather than that the conventional Wood's Nickel won't work for you, but it is not easy to know from such a brief description exactly what it is. Are you sure the parts exhibited no water break as they came out of the rinse before Wood's Nickel, and are you sure you're not over activating and generating that slightly black color as a smut in the acid tank, and that you are using sulfur-free anodes?

Regards,

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



March 8, 2019

Q. I'm performing a Wood's Nickel Strike on a copper cylinder external surface before plating 1 mm thickness with nickel sulfamate.

Wood's Nickel strike worked well for several weeks, (I successfully plated another copper part 2 hours before this problem occurred)

Wood's Nickel strike is performed as follows:

2 min anodic at 1.5 ASD
25 min cathodic at 3 ASD
A:C ratio close to 1

After this, the part has a black film on some zones, quite soft, you can see it on the gloves if you touch the part.

My fear, could it be the A:C ratio too small?
I decided to plate anyway with sulfamate nickel, to see how it goes.

Thank you all for your suggestions, Regards

Luca Manni
Mechanical machining of metals - Rome, Italy


March 10, 2019

A. Do NOT do the anodic cycle, that is plating copper onto the anodes, and contaminating the solution with copper. Go straight cathodic with the part. Take out the anodes when not in use to prevent the metal from climbing.

robert probert



Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
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August 28, 2020 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi,
I am using Wood's Nickel bath with this concentration:
Ni chloride - 260-280 g/lt & HCl - 65-85 ml/lt.

I'm facing black finish on LCD area as well as full black coverage. I took Hull Cell panel also, same result observed. I gave carbon (3 gm/lt) treatment to bath at 70 °C. After treatment I filtered all solution, clear carbon from solution.

Hull cell taken, are ok. But after 3-5 days LCD area starts blackish in bath, same result also seen in again. After treatment bath, not use, still Hull gets black. Dummy given to bath 1.5 V. No improvement. Dummy gets black not bright finish.
Is there any another method to give treatment to bath, or how do I remove that blackish finish?
We run bath at 3 volt. Bath volume is 200 lt.

Sandip Wandre.
- Pune, Maharashtra, India


August 30, 2020

1. HCl way too low.
2. 3 volts is not enough to activate, all you are doing at 3 volts is plating copper in the lows.
3. Apparently you left the anodes in while idle and the metal concentration increased thereby changing the low efficient "strike" into a high efficiency "plating" solution.

robert probert



Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
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