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Project to cobalt plate autos for corrosion resistance

I am working on a science project for my honors science research class. We plan to advance to the state and possibly national level with our projects. I am researching the effectiveness of different metallic plating applications, using different types of metals. I am most interested in using cobalt. I plan to test the corrosive resistance of the plated metal, especially against rust. I feel this project is relevant for people living in the Midwest that have problems with salt corroding the metal on their cars. I am having a problem deciding which application process to work with and was wondering if anyone could offer advice.

Kathryn T.
Hamilton Honors Science Research Program - Chandler, Arizona, USA
2003

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We applaud your ambition, Kathryn, and wish you the best of luck! But it sounds just a little bit like you feel those of us who have spent our entire lifetimes in the finishing industry trying to improve corrosion resistance are bumbling idiots to whom it never occurred to consider cobalt plating to keep salt from corroding cars :-)

Are you considering this cobalt plating for the brightwork, or for use under the painted areas, or on top of the paint. I'm having a little trouble picturing where and how you want to use this cobalt plating. Cobalt is electroplateable, so electroplating is probably the best application process to use.

There is a general problem in using a noble metal plating like cobalt to retard corrosion, instead of an active metal like zinc, and that is that if the underlying steel becomes exposed, galvanic current between the cobalt and the steel will greatly accelerate the corrosion of the steel. When nickel plating is used on the brightwork of autos it is applied in two layers, the top one of which is sacrificial to the bottom; thus is a scratch develops, the top layer corrodes in preference to the bottom layer, so the corrosion spreads laterally instead of penetrating in towards the underlying steel.

If you can be more explicit in your questions we can try to help. Best of luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003