Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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PO2 conversion coating for Thixo Mag?
Q. 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,
- Spokane, Washington, USA
2006
by Dow Chemical Co.
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A. 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%.
- Goleta, California
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