The effect of water in a methanol solution containing 0.42 wt% LiCl on the corrosion
behavior of type 316L stainless steel was evaluated by anodic polarization and
electrochemical impedance spectroscopy (EIS) at 423K and 473K. The addition of water to
the methanol solution increased the anodic dissolution potential (Ea) at both temperatures.
At 423K, an increase in the corrosion potential (Ecorr) was observed and the passive region
was reduced by the addition of even small amounts of water. The specimen surface
structure after anodic polarization measurements changed from a localized tarnish to pitting
with an increase in the amount of added water. A random plot of electrochemical impedance
spectroscopy (EIS) results showed typical pitting corrosion at an initial stage caused by an
autocatalytic process. The water impurity increased the risk of chloride attack at 423K.
Corrosion was activated as the added water volume increased. At 473K, no corrosion
occurred, regardless of the water concentration.
Key words: methanol, anodic polarization, electrochemical impedance spectroscopy,
corrosion