Galvanic Corrosion Iconel/Aluminum Prevention 2

[terning]

Does anyone know what precautions need to be taken in order to protect aluminum from Inconel 600? Can Inconel be passivated similar to the way stainless is passivated. The Inconel parts will be wet installed to provide a protective barrier. Any comments and insight will be greatly appreciated. Is there any particular vendor better than another for procuring Inconel 600? Thanks for your time and assistance.

Brett

 

[TVP]

There is only one producer of Inconel 600: Special Metals, formerly known as Inco. Other companies produce alloy 600 (UNS N06600) such as Carpenter (Pyromet Alloy 600) and Allegheny Ludlum (AL 600). For more information on use of these alloys, view the technical data available from the producer's websites:

http://www.specialmetals.com/products/inconelalloy600.htm

http://www.cartech.com

click on Technical Information then Alloy Name

http://www.alleghenyludlum.com/ludlum/pages/products/xq/asp/P.89/qx/product.html

Regarding galvanic corrosion of an Al alloy vs. a Ni alloy, wet sealing the Al is a common method used to minimize this. I'm sure others will post more specifics based on their experience.

 

[tbuelna]

Brett:

It is standard aircraft practice to "wet" install things like cres bushings, threaded inserts, studs, etc. into aluminum. The material used to wet install into aluminum is typically something like zinc chromate primer.

It is also standard practice to passivate inconel. The purpose for passivation (basically a nitric acid dip) is to remove impurities from the surface of the inconel, that may cause corrosion.

regards,
terry

 

[yates]

Inconel bolts in contact with aluminum have, more often than not, a protective layer of aluminum applied by either Al-loaded paint (NAS4006) or IVD (MIL DTL 83488). Maybe the size of your part does not lend itself to such a treatment.

 

[terning]

Hi Guys!

Thanks for all of your help and advice. It started me down the proper path. Your help saved time and iterations.

Best regards,

Brett

 

[rvdv]

If you need to guaranteed a high degree of galvanic corrosion resistance between bolts of Inconel and Al you need to put an interposition product on the contact surface. You can use ‘PR 1776 A AS’ but the final choice will also depend on the fluids susceptibility resistance (if Skydrol, de-icing, … is required), the viscosity of interposition, hermetic or not (for fuel tanker) ...
If you need to have galvanic corrosion protection and electrical conductivity or EMI/lightning shielding, there are also product available (PR 1764).

Best regards,

Rvdv