help with corrosion protection for steels

[Thinksalot]

I am seeking a corrossion inhibitor for a use on 4130 and 4140 steels. Cadmium is the present product in use, but is no longer feasible due to bioenvironmental concerns. I need a coating that is either durable enough not to come off or scratch in rough handling environments, with sub-zero to desert heat cycling conditions, and high velocity air streams. Alternately, it needs to be easily serviceable so that technicians in the feild can reapply it to scratches. It needs to be bio friendly. And not prohibitively expensive, like TiN. I am treating flat plates and also bolts. Obviously, film thickness will be a concern with the bolts. Any help is much appreciated.

 

[WKTaylor]

Try:
IVD Aluminum [AMS2427]
IVD Cadmium [AMS-C-8837]
Zinc-Nickel Plating [AMS2417]

Regards, Wil Taylor

 

[rustbuster1]

This sounds like a job for inorganic zinc, depending only on how much wetness time the sufaces experience. If they are occasionally wet - as oppposed to immersed or wet most of the time - then an inorganic zinc coating will meet the requirements you posted. Hard, rugged, easy to maintain and wide thermal range durability. Look them up on

http://www.google.com

to learn more about them

 

[gdodd]

Try mechanical plating of zinc or zinc alloy initially followed by a chromate conversion coating, then a zinc rich paint such as zinc silicate (as above) for repair.
Keep away from electroplating on this type of steel as it can be susceptible to hydrogen embrittlement.

Good Luck