无铬纳米锌铝涂层的微观组织及腐蚀性能

向无铬锌铝涂层中分别加入3种纳米微粒ZnO，TiO₂和SiO₂制备纳米复合涂层，通过盐水浸泡实验和电化学测试研究其耐蚀性，结合SEM等手段观察纳米复合涂层显微组织及其在盐水中的腐蚀情况，分析纳米微粒在涂层中所起作用。结果表明，3种纳米微粒的加入能够加强涂层的阴极保护作用，并能延缓涂层金属粉末的消耗，较无铬锌铝涂层更易减慢腐蚀速率。其中，纳米SiO₂复合涂层耐蚀性最佳，纳米TiO₂复合涂层略次，ZnO纳米复合涂层耐蚀效果较差，3种纳米复合涂层耐蚀性均优于无铬锌铝涂层。

Microstructure and Corrosion Resistance of Cr-free Nanocomposite Zn/Al Coatings

In order to improve the corrosion resistance of chromium-free Zn/Al coating, three different nanoparticles, eg. SiO₂, TiO₂ and ZnO were added in the coating respectively to form nanocomposite coatings. Corrosion properties of the nanocomposite coatings were examined through salt water immersion method and electrochemical method. Furthermore, the microstructure and corrosion products of the coatings were analyzed by means of SEM and EDS. The experimental results showed that the nanoparticles dispersed in the coating in the form of flake structure which formed a more effective physical shield, extending the path of the corrosive medium to substrate. Furthermore, the fine grain strengthening was dominant to make the coating a good shielding property when nanoparticle was added. Tafel curves indicated that the nanocomposite coating with SiO₂ possessed the best cathodic protection among three nanocomposite coatings, and the corrosion resistance of three nanocomposie coatings was better than that of the chromium-free Zn/Al coating.