The generalized chemical potential diagram for multi-component systems at high temperatures can provide useful and crucial information in examining materials behaviors in various environments including interfaces of dissimilar materials. This approach cannot apply directly to room temperature chemistry to be analyzed using the Pourbaix diagrams. Key concepts are discussed in terms of reasonable treatments of solid-solution equilibrium in view of kinetic considerations on nucleation and diffusion which make different room temperature chemistry from that at high temperatures. New construction strategies for multi-component Pourbaix diagrams are proposed with an emphasis of congruent dissolution process. Application to electrochemical process such as lithium batteries is shown as an interesting example.
Corrosion behavior of materials in aqueous solution can be quantitatively analyzed by simulation with electrolyte thermodynamic model, electrochemical kinetic model on material surface and mass-transfer and adsorption models between solution and material surface. This report introduces thermodynamic analysis method by real solution stability diagram, general corrosion rate estimation method by simulated polarization curves and localized corrosion susceptibility evaluation method by repassivation potential with concrete validation examples.
A new method for estimating the current of sacrificial anodes and the surface potential of the structure from the potential measurement was developed. The observation equation is formed by finite element method considering the geometry of the sea structure. Since this estimation problem is ill conditioned, the Bayesian Estimation approach is employed to overcome the problem. In order to demonstrate the effectiveness and efficiency of the present method, the verification experiment was performed at the real steel structures. This method enables us to estimate the corrosion protection state of the marine steel structure with easy inspection.
It has been reported in the previous studies that anions like Cl－, Br－, and I－ inhibit and those like SCN－, SH－, and S2O32－ stimulate the anodic process of iron corrosion in 1 M HClO4. These effects of anions on the anodic process were interpreted on the basis of the hard and soft acids and bases principle. The former three anions classified into the soft bases suppress the anodic process by the formation of a stable adsorption bond on bare iron, a soft acid. The latter three anions of the soft and hard bases accelerate the process due to soft acid-soft base and hard acid-hard base interactions.