Zn含量对冷镀锌涂料的腐蚀保护机制的影响

old galvanizing coatings were prepared. The coating properties were characterized by salt spray test and electrochemical impedance spectroscopy. Among others, the coating with 95.2% (mass fraction) Zn exhibits the highest corrosion resistance to salt spray, and its corrosion product consists of ZnO and Zn(OH)2. When the Zn content is less than 75%, the impedance of coatings in the solution of 3%(mass fraction) NaCl decreases with the increasing immersion time, and thus the coatings provide inferior protectiveness; when the Zn content is greater than 75%, the impedance of the coating decreases firstly and then increases with the increasing time, which may be ascribed to that the Zn powder in the coating acts as sacrificial anodewhich was preferentially corroded in the initial statge.