Surface characterization of the commercially pure titanium after hydrogen charging and its electrochemical characteristics in artificial seawater

The surface film on hydrogen-charged commercially pure titanium and its influence on the electrochemical behavior in artificial seawater was studied in detail using surface characterization techniques and electrochemical measurements. The results revealed that with the increase in charging current density, the original surface film underwent three stages of evolution. When the charging current density was <20 mA/cm², the surface film just expanded and bulged; when the current density exceeded 30 mA/cm², the surface film was significantly destroyed and began to fall off; when the current density reached to 50 mA/cm², the surface film fully peeled off and was replaced by a new layer of loose film. Accordingly, the composition of the surface film transformed from titanium oxides to a mixture of titanium oxides and titanium hydrides, and finally to entirely titanium hydrides. Under the influence of hydrogen charging, the corrosion resistance of the surface film in artificial seawater sharply decreased, showing a significant increase in anodic current density, decrease in surface film resistance, as well as a tendency toward early failure of the surface film at a lower potential.