Metal finishing Q&As since 1989

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Corrosion of the interface between a brass stud screwed into an aluminium body. DC Electrical Current carrying.

2006

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

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First of two simultaneous responses -- 2006

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.

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Second of two simultaneous responses --

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

2006

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[Note: NO-OX-ID 'A-Special' is sold by Sanchem Inc.

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.
2006

 

Ed. note: Thanks for observing that, Ken. For this site to function requires two things, commercial support from our advertisers to pay the bills, and helpful advise from people like you and Khozem. Your depth of knowledge and continuing willingness to work so hard to help people amazes us.

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

Frank Flinders
- Brisbane, Australia
2006