Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Pitting on nickel plated aluminium
2007
Q. I've been plating nickel on aluminium,for over 10 years,but the last 18 month's I seem to be constantly battling pitting,but only on aluminium.some days its fine,but most days it starts off ok,but gets worse after time.also the pitting seems to be quite random,as some articles are affected and some are not,even though all article's are plated on the same jig, I have 2 nickel tanks and get this problem in both. all aluminium articles to be plated,are highly polished first.
1 cleaned in ultra sonic
2 swill
3 minco. electrolytic cleaner
4 swill
5 66 microetch
6 swill
7 zincate
8 swill
9 66 microetch
10 swill
11 zincate
12 swill
13 nickel
I have tried triple dipping,I have a new zincate solution.I also check the microetch weekly{microetch is an alternative nitric acid}
please help.plates brass and copper fine.
plating shop employee - Stratford upon Avon, England
A. Maybe you can try to use the traditional pickle solution
(Nitric acid mix with amine fluoride).
I haven't used this kind of product like Microetch 66.
I know that this alternative indeed is more effective than traditional solution in some alloys. It also means that in
some alloys, it can't replace the traditional.
Hope the above is of help.
- Taiwan
A. Hi Simon
If the Zincate concentration/temp is okay
the etch would be my best bet.
The traditional etch using 2 volumes Nitric, 1 volume sulfuric conc and 160 g/l fluoride salt (e.g., Actane 70 from Enthone) could be the answer.
Regards
- Walsall, West Midlands, UK
February 13, 2013
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