Galvanic corrosion behaviour of hot-dipped zinc-aluminum alloy coated titanium-aluminum couples.

The hot-dipped zinc-aluminum alloy coating was used to avoid galvanic corrosion problems of titanium-aluminum alloy. The microstructure and corrosion properties of the coating were investigated by scanning electron microscopy, electrochemical measurement, and immersion test. The microstructure indicated that the coating consisted of outermost layer and middle interdiffusion layer, which metallurgically combined with the substrate. The electrochemical properties indicated that the coating on the titanium alloy decreased the electrochemical potential difference of galvanic couple. The corrosion current density showed that aluminum alloy contact with the coating changed the electrode, in other words, aluminum alloy specimen turned out to be the cathode in the galvanic couple. Immersion test was carried out to evaluate the performance of coating for galvanic corrosion, results confirmed that aluminum alloy contacted with coating on titanium-aluminum alloy exhibited less surface corrosion. [ABSTRACT FROM AUTHOR]