The seawater corrosion test of zinc steel plate in different seawater areas of Qingdao was carried out. The seawater corrosion behavior of the coating was studied for the first time through electrochemical test, weightless corrosion test and scanning electron microscope. The results show that due to the low corrosion current density, the corrosion products have protective effect, and the coating shows good corrosion resistance in the full immersion zone. The coating has different degrees of biological fouling in tidal range area, and more sufficient aeration conditions promote the oxidation of the coating, and its corrosion rate is obviously lower than that in total immersion area. There is no biological fouling in the splash zone, and the corrosion resistance of the coating is the best, which may be related to good aeration conditions and the blocking effect of corrosion product layer. The corrosion resistance of the coating in splash zone and tidal range zone is higher than that in full immersion zone by 65,438 0.97% and 65,438 0.83%, respectively. However, in the total immersion zone and tidal range zone, the coating has a local corrosion tendency.
In order to quantitatively compare the cathodic protection effects of different hot-dip galvanized metals (or alloys) on steel substrates in hot seawater, according to the requirements of national standard GB/T 17848- 1999, the constant current performance of several typical hot-dip galvanized and zinc-aluminum alloys was tested at 50℃, the current efficiency was calculated, and the corrosion product shedding and corrosion uniformity were observed. On this basis, their electrochemical protection performance was evaluated. The results show that Zn has the best electrochemical performance, while Zn-55Al- 1.6Si alloy has the worst electrochemical performance, followed by Zn-5al-0. 1Re, Zn-5al-0.5mg, Zn-6al-3mg and Zn- 16544.