Abstract
The foremost failure of several protective films, including Cr films, is corrosion at susceptible areas such as grain boundaries and intercolumnar areas. In this work, corrosion inhibition is introduced to eliminate the susceptible areas, by modifying the film structure. Consequently, an amorphous featureless film, without grain boundaries and intercolumnar areas, is successfully fabricated by co-deposition of Cr and Zr to form a CrZr film. Applying electrochemical impedance spectroscopy (EIS) test in 3.5 wt.% NaCl solution reveals that film crystallinity as well as its microstructure strongly affect corrosion behaviour. The amorphous featureless CrZr film effectively inhibits solution penetration, resulting in passivity and the highest film resistance (Rfilm). Apart from promoting amorphization, the addition of Zr retards corrosion reaction by the formation of ZrO2 on the film surface, as seen by the high impedance of film capacitance (Q(film)). X-ray photoelectron spectroscopy (XPS) confirms the coexistence of Cr and Zr in the film, which reduces the dissolution of ZrO(2 )and results in the high value of the oxide/ hydroxide ratio. Thus, both the high oxide/hydroxide ratio in the CrZr film together with low interfacial defects contribute to good corrosion resistance. Tailoring the structure of the CrZr film offers an alternative solution for the protection of many kinds of material from attacks of corrosion.
