EFFECT OF Zn ON ELECTROCHEMICAL PROPERTIES AND ANTI-FOULING ABILITY OF ETHYL SILICATE COATINGS

Abstract

Traditional antifouling coatings include paint layers: anti-corrosion primer, intermediate paint and
antifouling paint. To overcome the difficulty of bonding between paint layers, a coating that integrates
antifouling and anti-corrosion capabilities in the same coating on an ethyl silicate binder has been
researched. In the pigment mixture including spherical Zn, flake ZnAl and Cu2O, the effect of spherical Zn
content (30 wt%, 40 wt% and 50 wt%) on anti-corrosion properties was investigated by electrochemical
impedance spectroscopy and polarization curves. The results after 30 days of soaking in 3.5 wt% NaCl
showed that the total resistance of the coatings increased, and the corrosion resistance of the coating with
50 wt% Zn content reached the highest efficiency, the impedance module reaches the value 50,2 kΩ.cm
2
. The
polarization curve method also confirmed the corrosion protection of the integrated coatings following a
cathodic protection mechanism. Antifouling test results in natural seawater environment after 2 months of
testing showed that, with appropriate Zn content (30 wt% Zn), an integrated coating with the lowest fouling
density was created in the research samples, the coating surface only shows a biofouling film, the surface is
still visible under the fouling layer%. Test results show that the integrated coating has the ability to prevent
settlement and inhibit the growth of marine microorganisms for 2 months.