Corrosion of diffusion zinc coatings in neutral chloride solutions

The corrosion behavior of the diffusion zinc coatings based on the 8-phase FeZn7-10 in a solution of 3 wt.% NaCl in water was studied using electrochemical and physicochemical methods. Initial corrosion of the coatings involves selective dissolution of zinc from the 8-phase. As exposure duration increases, both components of the coating alloy dissolve. The physicochemical nature and electrochemical properties of the corrosion product layer were studied under conditions of simultaneous dissolution of the coating components. Iron can accumulate in the layer of corrosion products during prolonged corrosion of the coatings. In this case, the chemical composition of the electrolyte near the electrode and the structural and phase state of the corrosion products change. After long-term corrosion, the layer of products consisted of zinc oxide and amorphous hydroxide compounds of zinc and iron.