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"What alternatives are available for Chromate Coatings?"
We have been instructed to stop using Chromate Conversion Coatings due to the environmental concerns of Hexavalent Chromium. We have been using Clear & Yellow Chromate Coatings on Aluminum parts for electrical conductivity. What alternatives do we have to replace this finish?Samusel Ferguson
- Newark, DE, USA
First of two simultaneous responses -- 2005
I gave a paper at SurFin 2004. "Conversion coatings for Aluminum and Magnesium". It includes non-chrome processes. The paper is available from AESF [www.nasf.org].
Consultant - Poulsbo, Washington
(Don is co-author of "Plating on Plastics" [affil link to the book on: Amazon or AbeBooks ])
Second of two simultaneous responses -- 2005
You do have an alternative that gives you everything except the yellow color. The new products are based on trivalent chrome and meet or exceed the requirements of MIL-C-5541 and the conductivity test. This material has been in the works for a while now but until the pressure was put on by political and environmental groups changing wasn't eminent. Now things are really moving!
Ladson, South Carolina