anand

Topic: blackspots in tri-yellow

we plated the component with alkaline non cynaide zinc and passivated with tri-yellow and3months later sent to sea shore customer   there the component got black spots in all places.  in our place 3months we kept some components still with us are good condition give me good suggestion.                  

DustinGebhardt

Re: blackspots in tri-yellow

Metal tends to corrode faster in the presence of electrolytes like salt and moisture. 

Have you salt-spray tested  your pieces? 

Do they develop black spots as they age?  

How many hours do they pass?

You say you use tri-yellow.  I've never seen a tri-yellow that did not have dyes.  Is the dye reacting somehow?

How often do you change the passivate?  If you are building up contaminants, this could explain the spotting.  You may need to dump the bath more frequently.

-Dustin Gebhardt,
CEF
Plating Engineer
Danaher Tool Group
Gastonia, NC