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September 29, 2000
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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