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Peel off in between bright nickel and semi bright nickel layer
"The Sulfamate Nickel How-To Guide 2018"
by David Crotty, PhD & Robert Probert
Q. Dear sir,
I am a plating supervisor. I am facing peel off problem from semibright nickel. pH maintenance as per Coventya team 3.8-4.2 . Please sir some suggestions for me this time.
- YAMUNA NAGAR, India
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February 23, 2021
A. If there is another part being plated in the bright nickel, then when you enter the second part (with it's semi-bright), during the time before contact is made, the galvanic current passivates the semi=bright and then the bright nickel peels. Make contact externally before entering the bright tank.
Robert H Probert Technical Services
Garner, North Carolina
Previous closely related Q&A's starting in:2006
Q. I'm facing peel off problem in duplex nickel( peel of in between bright and semi bright nickel layer), the percentage of peel off is in PPM but even though its not acceptable. what may be the probable reason for this?generally this problem is seen in one particular component only. if we treated the semi bright solution next 2-3 days there is no peel of observed but it arises again after 3-4 days and daily we face problem in 4-8 pieces. Is this due to brightener chemistry? What brightener base shall we try to over come such problem? Or it may be mechanical problem?please advise.Milind Varadkar
Plating plant - Mumbai, India
A. Please give full bath and process specifications. What is your brightener and any other additives. Then we may be able to help
R&D practical scientist
Chesham, Bucks, UK
A. You did not give the sequence so I have not much details but anyhow remember that you should NOT rinse between the semi and the bright nickel.
chemical process supplier
A. To clarify your statement, your reject rate is in ppm(parts per million). You must have plated one million pieces before you observed the problem?
Organic brighteners have breakdown by-products during use.
Oxidation in the anode area, reductions in the cathode.
Why not give the semi-bright nickel the treatment after a day and a half of use?
- Mays Landing, New Jersey
A. Dear Mr. Milind,
motorcycle accessories mfgr.
- Aurangabad, Maharashtra, India
A. Dear Mr. Varadkar,
- Jakarta, Indonesia
A. Mr. Milind,
Let me give you another window to look at since I have spent 4 years in Sonepat running a duplex nickel line.
You say that if you treat the bath the problem goes away but comes back in 2 days or so. That tells me that you have cross contamination from the adjoining bright nickel tanks. If I am right then you are going in semi-bright and then immediate next tank is bright nickel.
The additives you use in the bright nickel have sulfur in them whereas there is no sulfur in the semi bright bath. So make sure that first, no one is mixing the additives, and second there is no cross contamination of bright solution into semi bright solution.
Check your filters also. Make sure no one is switching the filters between the two tanks.
Another thing, when you have done plating in bright tank then the rack should not cross over the semi-bright tank because it will give you cross contamination through falling solution. This means your semi bright tank should be at farther end and then as you are coming back towards unloading side, you are dipping/plating in the bright tank. I hope I have make myself clear enough!
Another way for just to detect the problem is STEP test. It will tell you the difference between the semi bright and bright layers. Why don't you compare layers of bright and semi bright on the parts, which have peel off problem. If there is not a big difference in the curve that will indicate that semi bright layer is slightly becoming a bright layer ... due to addition of sulfur based products in its chemistry...
VERY IMPORTANT THING MAN....you said you are rejecting only in PPM....are you sure about that ... I won't even do anything if my rejection level is at that level. Usually 3% level of rejection is considered optimum in plating shops...
- Florida, USA