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

Very adherent modified polypyrrole (PPy)(m) films have been electrosynthesized 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 oxidized and reduced states of the polymer, allowing the cataphoretic print technique, which is particularly useful in the automotive industry, to be used. When submitted to the salt spray test, the bilayer system (MS/(PPy)(m)/cataphoretic paint) appears to be as good as the reference system where the PPy layer has been replaced by a phosphating layer.