STUDY OF THE PROTECTION MECHANISMS IN ALUMINUM AND ZINC-ALUMINUM THERMAL SPRAY COATINGS ON STEEL IN ARTIFICIAL OCEAN WATER.

Of interest is the mechanism by which flame sprayed aluminum provides protection to steel substrates in a sea water environment. The mechanism was studied electrochemically using potentiodynamic polarization. Also of interest is the effect of alloying zinc with aluminum in a thermal spray coating. It is believed that the beneficial effects of both zinc and aluminum are obtained in the alloy coating because such a coating provides the sacrificial protection of pure zinc and at the same time, forms the impervious oxide film that is characteristic of pure aluminum coatings. As a result, the coating has a long life expectancy and also the ability to provide sacrificial protection to the base metal at flaws and holidays. Again, the corrosion mechanism was studied electrochemically using potentiodynamic polarization, the results of which are presented and discussed.