Corrosion prevention mechanism of epoxy zinc-rich primer

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1. The epoxy zinc-rich primer provides electrochemical protection. Since zinc is more reactive than iron and tends to lose electrons, during the early stages of corrosion, zinc powder and the steel substrate form a galvanic cell. The electrode potential of zinc is more negative than that of iron; therefore, zinc acts as the anode (often referred to as a sacrificial anode), while iron serves as the cathode. Current flows from zinc to iron, thereby providing cathodic protection for the steel substrate. It is also known as electrochemical anti-rust paint due to the electrochemical protective effect of its zinc powder on steel. 2. In epoxy zinc-rich primers, the zinc provides shielding protection against corrosion; during the later stages of corrosion, the zinc powder coating is continuously corroded, and corrosion products, namely basic zinc carbonate, commonly known as \"white rust\", accumulate in the gaps between the zinc particles and on the steel surface. It has a dense structure and is non-conductive; it is a stable, insoluble compound that can prevent and block the erosion caused by corrosive agents, thus providing corrosion protection. For this reason, it is also regarded as giving zinc powder paint its “self-healing” property. Therefore, it is also known as an organic zinc-rich primer.