Significance of Pourbaix Diagrams to Study the Corrosion Behaviour of Hardfacing Alloys Based on Chromium Carbides at 298 K (25 °C)

The Pourbaix diagrams also known as the E-pH diagrams were constructed for hardfacing alloys based on three chromium carbides: Cr 7 C 3 , Cr 23 C 6 and Cr 3 C 2 at 298 K (25 °C). Using the thermodynamic data available for the main species at 298 K (25 °C), Pourbaix diagrams for the chromium carbides are constructed at a concentration of 10 −6 M of aqueous species. It was found that the diagrams are able to explain the results of experimental work performed on chromium carbides in NaOH. It was found that the stability of carbides is described only by the immune region of the Pourbaix diagram for carbides. Although passive region has been included in the study, it was unclear from the literature if there was a passive film or how protective it was.