No cost, no registration, no passwords -- just aloha, fun & authoritative answers
(as an eBay Partner & Amazon Affiliate we earn from qualifying purchases)

Where the
world gathers for metal finishing
Q&As since 1989

-----

Low resistance inexpensive black coating on aluminum

1995

Q. I am a consulting design engineer (Mechanical) in the electronics packaging industry. In a recent project I encountered a need for a black coating on aluminum that was electrically conductive. Alternatives such as Black Nickel, Zinc, and Chrome over a copper and/or nickel flash have been discussed however they are cost prohibitive. Recently a black (or very dark) chromate tint was proposed. Can anyone suggest parameters or specifications for the process and sources for the tint? What cosmetic quality can be expected? Assuming it is (just) a bath change for the tint, would it be a major hurdle for local sheet metal fabricators to supply or is it best done by another source? Are there other suggestions of materials and processes to pursue? Thank you for your consideration.

Michael D. Miles, PE

A. Hi, Michael. MIL-C-5541covers chromate conversion coatings on Aluminum. For low electrical resistance, specify Class 3. This class achieves its lower rating via a thinner coating--which naturally sacrifices some corrosion resistance, and probably some of the saturation required for a dark coating.

There may be a proprietary that offers a shade dark enough to meet your needs, but I'd be surprised to find anything even approaching the saturation of a black electroplate or black anodize coating. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
1995

(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories: