Cobalt Pourbaix Diagram
Corrosion Potentials:
The Pourbaix diagram indicates that below a pH of 9 cobalt has the potential to form a corrosive ion. Since D.I. water typically has a pH value less then 6, thermodynamically cobalt can corrode.
Corrosion Rates:
The Tafel plots show that with the addition of a corrosion inhibitor, the corrosion rate of cobalt can be reduced from 4.42 angstroms/minute to 0.132 Angstroms/minute.