Corrosion inhibition of 70Cu–30Ni alloy in LiBr + ethylene glycol + H2O mixtures by inorganic compounds

The corrosion inhibition of a 70 wt% Cu–30Ni alloy in a 55 wt% lithium bromide (LiBr) + ethylene glycol + H₂O by inorganic inhibitors has been evaluated at different temperatures by using electrochemical techniques. Inhibitors used included lithium chromate (Li₂CrO₄), lithium molybdate (LiMoO₄), and lithium nitrate (LiNO₃), in a concentration of 5 ppm at 25, 50, and 80 °C. Employed techniques included potenthiodynamic polarization curves, linear polarization resistance, and potentiostatic measurements. Results have shown that the alloy had an active–passive behavior at 25 and 50 °C, and the passive film properties were improved with the addition of inhibitors, whereas at 80 °C the inhibitors did not have any effect. Similarly, in general terms, the best corrosion performance at 25, 50, and 80 °C was obtained by adding Li₂CrO₄, LiNO₃, and LiMoO₄, respectively. However, the alloy was not susceptible to pitting corrosion in presence of inhibitors but it was highly susceptible towards pitting type of corrosion in absence of inhibitors.