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-----Nickel plated brass sheet is staining
March 13, 2009
Hello everybody,
I have a problem of stain onto brass sheet which are nickel plated:
- Brass alloy : Zn39Pb2
- Brass properties : laminated sheet, very bright, protected with a plastic film and an acid engraving is made onto the brass before plating
- Process :
- Ultrasonic soak cleaner : 2-4 min depending the polishing compound to remove
- Cathodic degreasing : 30 s - 1 min depending the dm�
- Sulfuric neutralization dip
- Bright nickel : 3 A/dm� / 6 min
First, the brass seems to be oxidized after sulfuric neutralization, we do a wood nickel strike to hide these marks and it is ok.
Second, I have some clouds onto the bright nickel but not on all part
: from the batch, only 1 of 4 sheet has this mark.
We try a lot of parameters :
- we change the soak cleaner
- we put the sulfuric neutralization to the good concentration
- we check the bright nickel (Hull Cell ⇦ huh?
and sample plating to
3A/dm�): no cloud, pit or any nickel problem
My problem is : it is not a regular problem but some batches are ok without problem and some batches have 25% sheet with cloud problem.
Anyone has an experience or idea onto brass treatment and onto engraved brass treatment ?
Because I am very disappointed and this business is not good for me!
Thank you for your answer,
plating shop project leader - France
March 17, 2009
1. Try to add some peroxide (very small amount) into the sulfuric
2. You have lead in your alloy. You need a fluoboric dip prior to plating
Sara Michaeli
Tel-Aviv-Yafo, Israel
March 19, 2009
I THINK A ANDOIC CLEANING AFTER CATHODIC WILL HELP IN REMOVING CLEANING MARKS.
DO ANODIC CLEANING FOR 5 TO 10 SECONDS.
HAVE YOU DONE WATER BREAK TEST AFTER sulfurIC ACID DIP.
OR
A COPPER STRIKE BEFORE NICKEL PLATING WILL SOLVE ALL PROBLEMS.
REGARDS,
Ajay Raina
Ludhiana, Punjab, India
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