Chemical design, transport phenomena

Corrosion compromises structure safety and is a leading factor in the catastrophic failure in bridges, nuclear facihties, airplane components, and equipment used in chemical, petrochemical, transportation, and construction industries. Corrosion is a spontaneous, slow-progressing phenomenon. The rate is mainly governed by the environment, metal composition, and metallurgical, chemical, and electrochemical properties. Because it takes a long time to evaluate the extent of corrosion, it is often underestimated in industrial equipment and structure design. 

Solid ionic conductors that can be used in electrochemical cells as an electrolyte are called solid electrolytes. In such compotmds only one ion is mobile (see entry. Solid State Electrochemistry, Electrochemistry Using Solid Electrolytes). Generally, any conductor with a high ionic transference number can serve as an electrolyte. Often, the definition after Patterson is used who described solids with a transference number > 0.99 as solid electrolytes [1]. The transference number is not a fixed value. It depends on the temperature and the partial pressure of the gas involved in the chemical reaction with the mobile ion. Therefore, all solids are more or less conductors with a mixed ionic and electronic conductivity, so-called mixed conductors. For the application in sensors and fuel cells, only a window concerning temperature and partial pressure is suitable. This is also called as electrolytic domain. The phenomenon that solids exhibit a high ionic conductivity is also designed as fast ion transport. 

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