TITLE:
The Corrosion Protection Behaviour of Zinc Rich Epoxy Paint in 3% NaCl Solution
AUTHORS:
Nadia Hammouda, Hacène Chadli, Gildas Guillemot, Kamel Belmokre
KEYWORDS:
Zinc-Rich Epoxy Paints; Cathodic Protection; Electrochemical Impedance Spectroscopy;
Corrosion Mechanisms
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.1 No.2,
April
8,
2011
ABSTRACT: Electrochemical impedance spectroscopy (EIS) in the l00 kHz-10 mHz frequency range was employed as the main electrochemical technique to study the corrosion protection behaviour of zinc rich epoxy paint in 3% NaCl solution. The EIS results obtained at the open-circuit corrosion potential have been interpreted using a model involving the impedance of particle to particle contact to account for the increasing resistance between zinc particles with immersion period, in addition to the impedance due to the zinc surface oxide layer and the electrical resistivity of the binder. Galvanic current and dc potential measurements allowed us to conclude that the cathodic protection effect of the paint takes some time to be achieved. The loss of cathodic protection is due to a double effect: the decrease of the Zn/Fe area ratio due to Zn corrosion and the loss of electric contact between Zn to Zn particles. Even when the cathodic protection effect by Zn dust become weak, the substrate steel is still protected against corrosion due to the barrier nature of the ZRP film reinforced by Zn.