|
Letter 485
Can I skip the chromate on zinc
plating
----
Actually we have a system enclosed in a box made of steel plated
with zinc and yellow chromate. After I did some testing I found that
the chromate doesn't offer good conductivity. That doesn't make a
good shielded box.
If we only apply zinc with no chromate the finish is very
conductive but I was told that corrosion could occur rapidly. Is it
right ?
I'm looking for a finish or coating that
protect steel from corrosion
could be painted ???
is very conductive
relatively low cost
Could you help me or refer me to a company.
Best Regards
Francis Pelchat-
St-Léonard, Québec - Canada
----
Did you try "blue" or "clear" chromate - it is much thinner,
therefore more conductive.
You should not be afraid of corrosion - Zinc with or without chromate
provides almost the same degree of protection to steel. Without
chromate your finish is easily fingermarked though and will show Zinc
corrosion (white powder)much sooner than with chromate.
Max Stein
captive metal finisher - Montreal, Québec, Canada
----
Max is right, blue passivation is the correct answer. If blue is
still not good enough, try a short dip in 0.5% nitric acid. The
nitric does not improve white corrosion resistance but gives a better
appearance.
Sara
|
|
Sara
Michaeli
chemical process supplier
Israel
|
-
-
 |