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September 29, 2000

Chrome, cadmium, and nickel replacement information exchange

Jim Treglio

I have just returned from a DOD information exchange on replacement of chromium, cadmium, and nickel, and thought I would share some of the highlights with the visitors to this site. The meeting was organized by Concurrent Technologies Corporation, which operates the National Defense Center for Environmental Excellence (NDCEE). They are involved in a lot of the replacement programs, and, since the whole thing is military, suitable acronyms. You may want to contact them for details on the meeting. The focus is on replacement in existing military systems (mostly aircraft), not new ones, so it is very much depot driven.

The chrome replacement centered on two aspects of hexavalent chrome use: chromate conversion coatings and chrome plating for repair. Of course, several presentation missed the point, reporting on technologies suitable only for replacing chrome as used for wear resistance. A number of presentations centered on potential chromate replacement technologies, and it looks like there are great opportunities in that area. In the repair side, where hexavalent chrome is used to build-up to thicknesses of 10 to 15 mils, there is a major program underway to qualify HVOF thermal spray of WC/Co coatings.

The cadmium situation is not very well defined. From the military viewpoint, while there are a number of cadmium replacements for general use, such as IVD aluminum, but far less for fasteners and for high strength alloys. There are several programs ongoing for this area. There was a brief mention of work at Boeing in St. Louis on aluminum deposition for interior surfaces. There was also an interesting talk on a program to help a wet process for depositing aluminum/manganese alloy which raised great concern from the platers in the audience, alarmed by the potential hazards of the process.

It is interesting to note that composite nickel-based coatings were presented as a viable alternative to chromium for repair work in the same meeting looking for replacing nickel. I had to leave before the nickel replacement session, staying only for a presentation on the potential problems with nickel and government restrictions, both current and potential. It appears that the jury is still out on nickel itself as a carcinogen, though several nickel compounds are carcinogenic.

These meetings used to be held annually, but this is the first one since 1997. They are open to the public, so you may want to keep an eye out if they hold one in 2001. If nothing else, it will give you a good idea of where your tax dollars are going.

Jim Treglio <ismtech@ixpres.com>


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