Electrochemical Study of the Corrosion Behavior of PVD Coatings of Different Microstructure

摘要

Titanium, chromium and titanium-chromium alloy coatings were sputter-deposited in order to study their corrosion behavior in relation to microstructure and composition. Alloying of titanium with chromium greatly influences the microstructure of the coatings: alloying led to more dense deposits and in some cases to an X-ray amorphous structure. Alloy coatings showed significantly lower corrosion currents than the constituting metals. Electrochemical impedance spectroscopy (EIS) was used for the estimation of the real surface area of the coatings. When corrected for real surface area, however, the intrinsic corrosion rate of the alloy coatings was found to be comparable to that of the constituting metals. Porosity was found to be strongly influenced by the microstructure: columnar films led to a higher dissolution of the brass substrate through the pores.