Cadmium plating alternative

"Electroless Plating"
by Mallory & Hajdu

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A. Depending upon the specific application a variety of different finishes may be necessary to replace Cadmium. These would include zinc alloy, electroless nickel, tin, as well as a variety of vacuum deposition processes eg. Invadizer (is it still being sold under that name?). It would be necessary to do a part by part evaluation. The Airforce has done a lot of work on cadmium and chromium substitutes and some of the result are in the literature (trade magazines) and papers presented at various AESF events.

Good Luck.

A. I would guess that if you made any changes from the OEM standard practices that you would assume a 100% liability for anything that went wrong with the modified part. The lawyers would have a field day.

A. McDonnell Douglas developed the ion vapor deposition (IVD) process for the military over twenty years ago, wherein aluminum is deposited as a replacement for cadmium. IVD is a dry, batch process carried out in very large vacuum chambers. As aluminum is not a carcinogen, and the process is dry, it is considered an environmentally benign process. However, post deposition is pretty much the same -- bead blasting followed by chromate conversion. The process meets most military specifications. You can find companies at this site that do the work on a toll basis. There are also a couple of companies that sell the equipment if you want to do it in-house. The only area where it does not work as well as cadmium is on bolts -- aluminum doesn't have the same release properties.

A. There is no across-the-board replacement for cadmium, Eric, so you need to look at one application at a time, and you may find that cadmium must be replaced on part A with coating technology X, on part B with coating technology Y, and on part C with coating technology Z.

What cadmium offers includes lubricity for excellent stick-slip properties, great galvanic protection, substantial freedom from bulky corrosion products, softness & malleability, solderability, and compatibility with aluminum in both aerobic & anaerobic environments (like under bolt heads). Which substitute to use depends on which of these properties are important to the application. Obviously nothing has ALL of the properties of something else (or it would be that something else). So if you need all of cadmium's properties, but don't want to use cadmium, you're in trouble :-)