The Corrosion and Electrochemical Behavior of Tungsten-Based CVD Coatings in Alkaline Aqueous Solutions

Resumo

The results of corrosion-resistance analysis for tungsten-based coatings obtained by means of low-temperature chemical-vapor deposition from fluorine-containing media in alkaline solution are presented in this article. The study was carried out in the pH region where, according to the Pourbaix diagram, tungsten undergoes corrosion by the active dissolution mechanism. It is shown that, in alkaline solutions, the rate of general corrosion of a tungsten coating in solutions of natural aeration reaches values of 20–25 μm/year. An analysis of the electrochemical behavior of the coatings confirmed that the mode of corrosion dissolution is active, but it was noted that, in the region of high anodic polarization values, the growth of the anode current appears to be limited, which may be due to the formation of oxide layers that hinder the kinetics of anodic dissolution.