Evaluating Zn, Al and Al–Zn coatings on carbon steel in a special atmosphere

This paper presents a comparative evaluation of Al, Zn and Al–Zn coatings on carbon steel, exposed to a coastal-marine atmosphere. It is a very aggressive atmosphere with high wind velocities (corrosion–erosion rate ≈ 1.4 mm/year (55.12 mpy) for ASTM 1029 steel). Two flame spraying zinc coatings with pore sealers were also evaluated. ISO and ASTM standards were used for the evaluation.After a 2-year exposure the best performance was achieved by the flame spraying Zn/15Al alloy (85% Zn–15%Al) with some damage of the coatings. But the one with a wash primer pore sealer did not show signs of damage.