The performance of a waterborne zinc-rich coating from sodium silicate solution catalyzed by ammonium acetate

Through general property tests, rheological measurements, SEM observations and weight changes after immersion, electrochemical methods and water vapor transmission tests, a waterborne zinc-rich coating from sodium silicate solution catalyzed by ammonium acetate was characterized. Results showed that the formula catalyzed by ammonium acetate overcame the poor water resistance of other non-catalyzed coatings, while binding the zinc powder in the film. The zinc-rich film had the basic features required for a zinc-rich primer to be useful and was electrochemically cathodically protective during tests. The acetate anion from ammonium acetate resulted not only in little early corrosion while catalyzing the formation of zinc silicate before cure but also stronger corrosion protection during the immersion test on the cured film. The velocity of water vapor transmission and the amount of acetate anions present decreased with time until a stable value was achieved after approximately 6 days.