Corrosion behavior of carbon steel coated with a zinc-rich paint containing metallic compounds under wet and dry cyclic conditions

The corrosion behavior of carbon steel coated with a zinc-rich paint containing two metallic compounds, Al-2(SO4)(3) and CaO, as anticorrosive additives was examined under wet and dry cyclic corrosion test conditions. The zinc-rich paint coating without the two metallic compounds formed a white corrosion product and red iron rust on the surface after the corrosion test, whereas the coating with the metallic compounds showed reduced surface corrosion products. The corrosion current density of the painted steel substrate decreased drastically due to the incorporation of metallic compounds in the paint. The zinc-rich paint coating modified with the metallic compounds contained dispersed simonkolleite (Zn-5(OH)(8)Cl-2 center dot H2O) phase and possibly very fine CaSO4 particles, which remarkably improved the protectiveness of the zinc-rich paint coating.