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Analysis of Anodized Aluminum Part shows Strontium

I have an aluminum part that is anodized. The material analysis returned with a Strontium peak. Are there companies or specifications that control anodize with strontium?

Rich Collings
Aerospace - Springville, UT, USA
2006

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First of two simultaneous responses --

Neat question! Seems that strontium is used as an alloy modifier in some aluminum-silicon alloys. I hate to use the platers favorite response in this type of scenario, "it's in the metal" but surely it fits here. I've never heard of strontium being in any of our chemicals at all! A website that discusses this alloying use of strontium is http://www.key-to-metals.com/Article85.htm.

Milt Stevenson, Jr.
Syracuse, New York
2006

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Second of two simultaneous responses --

I am not aware of strontium use in anodizing.

Strontium at 0.01-0.02 wt% is commonly used as a grain structure modifier in Al-(5-13%)Si castings --- 316, 356, 357, etc. Traces are therefore also likely in recycled Al.

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