The salinity of seawater typically ranges from 1% to 25%, often approximated as 3.5% for calculations. Seawater contains substantial amounts of oxygen, nitrogen, carbon dioxide, and other elements, which can accelerate the corrosion of the zinc layer. Chloride ions (approximately 55% of the total ion count) hinder the formation of protective films and enhance corrosion. In contrast, magnesium and calcium ions readily react with the zinc layer to form insoluble salts, promoting the formation of protective films and gradually reducing the corrosion rate.
The corrosion products of the zinc layer in seawater include carbonates, hydroxides, chlorides, and other components. Generally, the corrosion rate of the zinc layer in seawater is between 50 and 650 milligrams per square decimeter per year.
