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PO2 conversion coating for Thixo Mag?

Our Thixo Mag caster in Taiwan says they use a PO2 coating before painting. Are you familiar with this treatment? If so how corrosion resistant is it? How conductive is it?

Thanks,

William Frederick Erler
- Spokane, Washington, USA
2006

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2006

PO2 commonly indicates partial pressure of oxygen. An online search, the FAQ on Magnesium Finishing and MIL-M-3171didn't reveal either a PO2 or P02 coating for magnesium. Check with the caster.

My guess (it's not my money!) would be phosphating. Further guesses: slight corrosion resistance (better if chromate sealed) & poor conductivity. Phosphoric acid can be used for pickling magnesium castings.

The DOW Magnesium Finishing booklet mentions primers: "Wash primers" are successfully employed on magnesium. To prevent blistering when used on magnesium, the phosphoric content of the primers described in MIL-C-8514 [from DLA] and MIL-C-15328 [now DOD-P-15328] should be reduced by 75%.

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.

 

Ed. note: Copies of the Dow handbook on Magnesium Finishing are sometimes available by following the link.