Appraisal of the polypyrrole/cataphoretic paint bilayer system as a protective coating for metals

Very adherent modified polypyrrole (PPy)(m) films have been electrosynthesi zed on oxidizable metals such as mild steel (MS) and zincated steel (Zn) by electrochemical oxidation of pyrrole (Py) on the substrate. In the case of mild steel, the adherence of the coating is maintained in both the oxidize d and reduced states of the polymer, allowing the cataphoretic print techni que, which is particularly useful in the automotive industry, to be used. W hen submitted to the salt spray test, the bilayer system (MS/(PPy)(m)/catap horetic paint) appears to be as good as the reference system where the PPy layer has been replaced by a phosphating layer.