What are the main factors that influence the zinc corrosion rate?
The corrosion rate of an exposed rolled zinc surface is influenced by: • sulphur dioxide (SO2), typically found in very urbanised or industrialised atmospheres, • chlorides, essentially present in a marine atmosphere, • the slope and direction of the exposed surface, • surface treatments. SO2 has the greatest impact: it is very soluble in rainwater which it acidifies. It attacks the protective layer of zinc hydroxycarbonate (patina) to form a soluble zinc sulphate which is washed off by rainwater. The corrosion rate of zinc is thus higher in highly industrialised areas.
