Chemical Thermodynamics of Corrosion

In any corrosion process, the solid metal, the contacting aqueous solution and, normally, an adjacent gas phase are parts of a system in which the reaction causes physical and chemical changes. A description of the system in terms of thermodynamics then requires the specification of the boundaries separating the system and its surroundings [1-6]: These may be permeable a) to both matter and energy, where energy is work and/or heat, or b) permeable to energy alone, or c) impermeable to both matter and energy. The system is then said to be a) open, or b) closed, or c)isolated, respectively.