Potential-pH Diagram for Sb-H₂O System and its Application at High Temperature

The potential-pH diagram for Sb-H₂O system at 100, 150, 200 C have been made using the available thermodynamic data, based on the criss & Cobble correspondence principle. The results obtained in the present study indicate that the stable region of antimony contracts and migrates towards more negative potential and lower pH especially within the alkali region when the temperature increases. As contrasted with the enlargment of the region referred to the ions of SbO₂^- and SbO₂^-, the region in which the antimony oxides of Sb₂O₃ and Sb₂O₅ are stable contracts as well with temperature because the stability of antimony ions increases with temperature. Eventually, the possibility for application of antimony coating to protecting steels from corrosion has been discussed with the diagram obtained in our study.