CORROSION PROTECTION BY ORGANIC FILMS

The corrosion reactions which take place at a defect free metal/polymer interface and the delamination in the vicinity of defects are not yet understood. In this paper several recently developed experimental techniques are applied to such corrosion systems to elucidate the fundamental corrosion processes for polymer coated metals. The transport of water and oxygen through the coating and the electrochemical reactivity of the coated metal are investigated using a quartz-crystal microbalance, FTIR spectroscopy and electrochemical dc and ac techniques with a special reference electrode positioned at the metal-polymer interface. The delamination of the polymeric coating in the vicinity of defects is analysed by the scanning Kelvin-probe. The combined application of these techniques leads to a corrosion model, which explains the corrosion protection of metals by polymers.