Steels continued corrosion behaviour

There is extensive literature on the corrosion behaviour of hot-dip galvanised steel pipes in cold water. In an experiment lasting 3 months on hot-dip galvanised N D 20 steel pipes in the types of water shown in Table 23 at a continuous flow rate of 0.12 m/s, it was found that the corrosion rate depends on the flow rate and the pH [42]. From theoretical considerations, this result is interpreted as follows a virtually stationary state is established in the three-phase system of metal/surface coating/ water, in which the transportation of Zn(OH) ions from the surface of the coating into the water by diffusion is the rate-determining factor. 

In another reaction, the yellow PAni is back oxidised to the basic green PAni. Therefore in the process of corrosion protection this behaviour is practically available for the build-up or the repairing of the passivating iron layer—or steel, copper, aluminium etc. These properties make a polyaniline primer interesting for hard applications too from falling stones, rocks or other injuries to the lacquer-structure the normally produced pieces began to produce mst at the site of these injuries, but the workpieces treated with PAni-lacquer were continually protected through the shift of the corrosion potential. 

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