Noble metal coating on 410 stainless 3

[awhicker84]

Hi all,

I was wondering if anyone in the API compressor world could especially chime in on this, but my question is the following:

What is the experience of using silver, gold, or platinum coating on a 410 shaft? Does it bond well? I haven't started looking at price yet. I'm wondering if it is exorbitant.

I've never seen it used. Curious if other heavy equipment industries use it sparingly in high corrosion / low erosion locations on their equipment.

Thanks and cheers,

 

[SJones]

Two questions:
1. Why do you need to coat a stainless steel?
2. What's wrong with nickel?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[awhicker84]

My answers:

1) We are stuck with a substrate (410) that is experiencing acidic and galvanic corrosion due to the customer's process. We will be looking into other materials on the next go around. We have what we have at the moment.

2) I'm looking into noble metals simply because I'm interested. I want the substrate to never touch the customer's process or have a long enough life that it could be removed and re-coated as required. Maybe the coeff of expansion may be a problem. I'm really just curious to see if anyone else has gone this route or why other people do not go this route.

Thanks for your response and cheers,

 

[SJones]

2) The precious metals are unlikely to have sufficient hardness for the rotating application. A certain international rotating equipment supplier offers a low alloy steel shaft sleeved with a corrosion resistant alloy in highly corrosive hydrocarbon gas compressors.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[EdStainless]

It isn't the CTE or the bonding that limits this.
It is that all platings are porous, and the 410 has such low corrosion resistance that every little gap will create accelerated corrosion of the 410.
This is why most people stick with Ni plate over a Cu flash.
If you need a hard coating go with EN and age harden it.
If you really need more corrosion resistance (not just occasional exposure) then change to the correct alloy.

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P.E. Metallurgy, Plymouth Tube

 

[TugboatEng]

Kanigen, an electroless nickel process, is commonly used to prevent corrosion in pumps and valves. Perhaps it would be suitable for your application.

 

[awhicker84]

Thanks for the responses. I'm not sure if Ni is appropriate as there is CO in the process and it looks like this is a potential reaction at the temps we are seeing (see Mond Process).

cheers,