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  for Metal Finishing since 1989
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Behavior of zinc plated steel in sea water

 

Interested in suitability of galvanised and zinc plated steel in seawater especially at temperatures around 25degC. Benefits of chromate passivation?

Dave Elliott
- UK

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Zinc is not too good around sea water as the corrosion resistance in part depends on the formation of a layer of corrosion products of zinc on the surface that then help to protect the under laying zinc layer.

The problem is that the zinc will form zinc chloride which will dissolve and leave the zinc unprotected, rapid removal of the zinc will result with vastly reduced service life.

Passivation will slow this to a small degree but the bottom line is zinc and sea water are not a good combination.

As to what else you could use this depends on a lot of other factors which more would have to be known about before suggestions could be made.

Martin Trigg-Hogarth
surface treatment shop - Stroud, Glos, England