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Corrosion of brass stud in aluminium, carrying DC current

Hi my name is Frank Flinders

I have a problem with a bad electrical joint developing in a brass stud taped into an aluminium body.

Is there potential for corrosion between a brass stud screwed into a threaded aluminium body. The stud carries a high level of DC electrical current. Electron flow is from the Aluminium to the brass.

Thank you,

Frank Flinders
- Brisbane, QLD, Australia
2006

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Hi Frank,
The aluminum will galvanically corrode in the presence of moisture.
To prevent, use electrical joint compound (EJC) on the stud threads before inserting. EJC's are waterproof greases (or wax for high T), contain corrosion inhibitors, some can dissolve surface oxides and some have fine zinc particle filler for improved conductivity. Use one rated for aluminum-to-copper connections (and high temperature if applicable). Some brands are Alcoa #2 & Alnox, Burndy (Penetrox A & A13), Hubbell (Anderson # VS8HTJC), and NO-OX-ID 'A-Special.'

For more information, see 'ELECTRICAL CONNECTIONS FOR POWER CIRCUITS' from the US Bureau of Reclamation:
http://www.usbr.gov/power/data/fist/fist3_3/vol3-3.pdf

Also, check applicable electrical codes.

Ken Vlach [deceased]
- Goleta, California

Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.

Aluminium will corrode when contacted by brass. You may need to Bronze plate the Brass, Bronze will not initiate any corrosion in the Aluminium.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

Thank you for your very useful replies. We have used a jointing compound to exclude the possibility of ingress of any moisture.

Frank Flinders [returning]
- Brisbane, Australia

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