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Plating S.S. without a Woods Nickel Strike

Q. What I was wondering,is there a way to plate stainless steel without a woods nickel strike. I have heard that someone is doing this process without the woods nickel strike and was just curious to know if anyone has heard of this or is it even possible?

Brian Gaylets
- Scranton, Pennsylvania, U.S.A.
2004

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Q. Guy, how do you clean and activate your stainless steel to obtain good adhesion? Can you give details please, because I have never had any reproducible success with conventional systems.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2004

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A. We routinely coat SS base metals by means of Physical Vapor Deposition (PVD). Anything from pure metals such as chrome, to compounds such as TiN or CrN, so it's a realistic alternative for your parts. Joe Kubinski PVD equipment supplier - Woonsocket, Rhode Island, USA 2004 ? I have worked for two companies that were certified for Pratt & Whitney plating. I have been out of PWA plating for a while, but PWA required a strike for all SS when I was active. Are you in conformance with PWA SPOP's? Also, you do not say what your adhesion test is and do you consistently pass it. James Watts - Navarre, Florida 2004 A. I do a lot of stainless steel auto trim. It is usually kind of crappy so I sand it with 80 grit on a D.A. Then up to 120 and finish with 220. Scrub well in a 1/4:1 sulfuric/water bath and then into my nickel strike bath. (High sulphate nickel strike) Or, if you have cyanide it will do the job. After a 10 min strike in the nickel strike, rinse and into the copper for a hour. The rest is just sand, buff, clean, nickel, chrome. Tom H [last name deleted for privacy by Editor] - Peoria, Arizona, USA 2004

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? Jeffrey-

What alloy and will a non-struck part pass a bend test?

James Watts
- Navarre, Florida
2004

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2004

Q. This thread has struck a real chord with me, so please excuse me in advance for being longwinded.

I've been trying to develop a process to plate nickel and then gold over small (in the neighborhood of .4 sq inches surface area per piece), intricately shaped components for over a year now. I'm using a barrel plating process which likely increases the challenge, but I've tried 3 or 4 different processes in 30 or so configurations, and I've yet to find one that passes a crush test to the required standards.

The basis material is 303 stainless steel, and on my most successful trials I get 2-3% adhesion failure in crevices and at edges. Failures usually occur in the areas of highest stress after crush, which should really come as no surprise. I know that it is possible to do better, because we've had a vendor plate the same components, and they've passed the test every time.

The first process I looked at was an HCl activate followed by a Wood's Ni strike. As mentioned above, I've seen that after 2 or 3 uses, the steel no longer gases and the HCl must be replaced. But even with fresh, undiluted HCl, I see failures. I've tried running reverse current through the parts while in the HCl, and that failed as well.

I next explored a reverse current activate in 60% sulfuric, followed by a strike in a sulfuric/low conc NiCl bath. Failures there as well.

Most recently, I've looked into an extremely low conc. copper strike mentioned in a gold plating text. I used the same sulfuric activate as above followed by a strike in an HCl / .3 g/l Cu sulphate-pentahydrate bath. I actually managed to get 100% adhesion on my first trial here, but visually the parts finished very ugly, and follow-up trials soon began to exhibit adhesion failures.

Before beginning the activate, I clean the steel in a hot alkaline soak cleaner. After activate the parts get 50-100 micro-inches of nickel in a brightener free nickel sulfamate bath (pH 4.0), and then 50-100 micro-inches of gold in an acid PGC bath. In all cases I try to minimize the time between activate and strike, and if the acid is the same between the two I do not rinse at all. I've also tried going into the Ni plate bath at extreme current density and then slowly dropping it back to my operating current density. (8ASF) I've tried lot sizes as small as 1/10 of a square foot, and as large as half a square foot and have seen no appreciable difference.

Can anybody see what I'm doing wrong? Recommend a process that I haven't tried or a change to a process I have? I'm beginning to wonder if our vendor isn't using some sort of voodoo magic.

Thanks for the help,

-Ray

Raymond Brown
- New Hanover, Pennsylvania, USA

A. Brian

In Pratt North Berwick. We run to (POP's) Process Operation Procedures. Our POP 140 allows us to Nickel plate SST. Depending on which alloy it is we REF. AMS2403-ams2424.

1. Electrolytically clean using Alkali solution. Tank temp. 130 °F ±10. Cycle Time: 4 ±1 Minutes. At 25-65 Amps/Sq. Foot. Have current anodic at end of your 10 sec. periodic reverse cycle. Rinse parts in clean DI water.

2. Immerse parts in a 50% Hydrochloric acid solution at room temperature for 45-60 seconds after gassing starts for 30-60 seconds.

3. Pressure Rinse parts thoroughly to loosen smut in DI water.

4. Transfer quickly and immerse to the nickel bath.

Guy Boucher
aerospace - North Berwick, Maine, USA
2004

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Thanks for the reply, James. You've mentioned some interesting things.

Our parts are not baked in any fashion, and do not see a buffing process, but I will certainly explore more extensive pre-cleaning.

Is the deposit put down by a Wood's Ni strike highly stressed? It seems that adhesion on all of our substrates is highly sensitive to stressed nickel deposits. I see major failures even on copper substrates when I add just a small amounts of brightener to the nickel bath. My deposit is not that thick (75 microinches or so), so I've never really been able to explain that phenomenon.

Is the temperature of the Wood's nickel a factor? I've never tried heating the bath, even though most production nickel baths run warm to hot...

I'll do some more experiments over the next day or two and see what kind of results I get.

Thanks again,

Raymond Brown
- New Hanover, Pennsylvania, USA
2004

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A Woods nickel strike has a very high internal stress. That is one reason to only put enough on to get a uniform coating. At one shop we used 300 amp minutes per Sq Ft. Room temp is the proper temp, 70 °F±. The anode material needs to be rolled depolarized. Electrolytic nickel would be OK, but not SD or RD rounds / crowns / pellets. James Watts - Navarre, Florida 2004 Like someone had mentioned above, try an electrocleaner on your parts. I am not familiar at all with gold plating, but for what we do we run our soak cleaner at 180 °F, with a 10% makeup. Also another good point is when we make up our cathodic acid (I forget the percentages) we beef it up with 25# of ammonium bi-sulphate (something new we are trying); we have found that this is working great for us in plating Ni over stainless steel! Brian C. Gaylets - Scranton, Pennsylvania, U.S.A. 2004

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April 23, 2018

Q. We are currently investigating different methods to activate 303 Stainless Steel. On this thread you indicated you use the Ammonium bio-sulfide method. For the 25 lb makeup, how many gallons is your tank, temp, how many ASF or volts and how many minutes? What is the cathodic acid chemistry and if you have makeup? You indicate that you add the ammonium bio-sulfide with the cathodic acid?
Mark

Mark Williams
Foresight Finishing LLC

- Tempe, Arizona

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Wood's Nickel Strike isn't giving good adhesion

Q. Hey guys, can anyone give me a quick conversion from metallic nickel content to NiCl2(H20)6?

Having extreme difficulty with my Wood's bath all of the time, just now got murexide [affil links] in to titrate and determine what is actually happening.

Using procedures from the Metal Finishing Guidebook, titrated the Woods tank 2 mL sample, 100 mL DI H2O, 20 mL conc. NH4OH, bit of murexide [affil links] in NaCl. 0.1M EDTA. Measured 17.2 mL to a fairly abrupt orange to purple color change, by my calculations gives me roughly 6.75 oz/ gal Nickel metal.

Then setup for acid titration, 10 mL sample, 100 mL DI H20, bit of methyl orange ⇦this on eBay or Amazon [affil links] , Titrated with 1.0 M NaOH [1N NaOH on Amazon [affil links] ever so slowly to keep the Ni from precipitating to a sickly green endpoint. Measured 15.2 ml. Now should I titrate for Chloride content as well? I feel like I am missing something simple, any recommendations would be quite welcome, or any additional information needed. It may be just me but the solution appears to be slightly thick, not viscous, but it behaves more slowly than water if that makes any sense.

I have drained the tank, and cleaned it, of course several small parts my operators had no idea how they could have gotten there but I am at a loss. I often have a skip plate, or just an awful black loosely adherent film. This tank is used primarily for barrel operations. Again, I am sure there are several issues but I would like to begin knocking down those that I can. Thanks in advance for any help.

Jordan Egnatoff
- Huntington, West Virginia, USA
November 1, 2018

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Ted and Robert,
Thank you both for your insightful and quick responses.

Ted, if I am understanding correctly the 6.73 oz/gal Ni metal content I measured through titration should convert to a Nickel Chloride Hexahydrate concentration of 27.24 oz/gal? Assuming I have done that correctly my concentration of HCl (36%) was 16.94 fl oz/gal which from what I have read is low if I am attempting to keep a 1:1 ratio of the two components.

As for the fallen components, I wholeheartedly agree and have gone through great lengths to educate the operators about it, however, I was only trying to provide as much info about the tank as possible as I have often read that that is the first step in troubleshooting a Woods baths from this site. If at all possible would you or any other reader be able to confirm my figures and offer a possible course of action before I go adding an extra 10 fl oz/gal HCl to the tank? Also, I am concerned about metallic contamination from the aforementioned parts and would be grateful if anyone could suggest whether or not dummying the tank might offer some relief and if so what current density may be the best move. I am interested in saving this tank as opposed to making a new one if possible. Thank any and all in advance as usual, I patiently await your feedback.

-Jordan

Jordan Egnatoff [returning]
- Huntington, West Virginia, USA
November 5, 2018

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Q. Ted, thank you again for your invaluable guidance, just for kicks, if I were to dummy with rolled anodes to remove other metallic contaminants, such as copper for instance, is there a current density you or another poster might suggest? Or perhaps a chapter or reference in the guidebook which could point me in the right direction? I apologize for the continuing questions, thank you so very much for your input.

Jordan

Jordan Egnatoff [returning]
- Huntington, West Virginia, USA
November 6, 2018

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No worries, I went about 3 A/ft^2 did manage to pull out a bit of copper, mostly in LCD areas of my plate, adjusted for HCl accordingly find out today whether or not there will be a noticeable difference. Thank you again for the wonderful help. Jordan Egnatoff [returning] - Huntington, West Virginia, USA November 7, 2018 A. Hi Jordan, We've dummied copper out of a wood's nickel strike down around 5 ASF but honestly it's way more efficient to just make up a new one. I'd recommend some kind of corrugated sheet because the copper immersion plate loves LCD areas. Without live entry the copper tolerance is really low so dummying only buys a little time. Not sure what your substrate is but find ways to reduce the copper introduction and don't be afraid to dump and recharge. Jameson Grout - Springfield, Massachusetts USA November 7, 2018

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