Inhibition mechanisms of corrosion Inhibitors for metals are closely related to the hard and soft acids and bases （HSAB） principle. Markedly high inhibition efficiency of decamethyleneimine （CH₂）₁₀ NH was explained by the formation of a stable chemisorption bond between iron and nitrogen atoms caused by a high strain in the ring using this principle. The anodic processes of iron corrosion in the presence of inhibitive or stimulative anions were discussed on the basis of the HSAB principle.

The applicability of hyperspectral analysis has been investigated as the evaluation method for corrosion resistance of steel materials. As a result of hyperspectral measurement of known iron-based corrosion products, it was confirmed that the wavelengths for reflection and absorption differ depending on the corrosion products. The normalization index analysis was carried out for the hyperspectral of the surface of the steel materials exposed to coastal area, which showed that the larger the amount of corrosion change, the larger the obtained index.

To evaluate the effect of oxidants, which are formed by radiolysis of water under gamma ray irradiation, on the corrosion of a carbon steel in a humid environment, ozone was introduced as a model oxidant into humidity-controlled air at 50℃ in a thermo-hygrostat chamber. Corrosion monitoring of carbon steel was performed by using an Atmospheric Corrosion Monitor-type （ACM） sensor consisting of a carbon steel anode and an Ag cathode, and a Resistmetric Corrosion Monitor （RCM） sensor consisting of carbon steel sheets. The corrosion rates obtained from the outputs of the sensors were increased with the increase in relative humidity and were obviously increased with the increase in the introduced ozone concentration at each relative humidity, indicating that ozone accelerates the corrosion of the carbon steel. The effect of ozone on the corrosion acceleration is attributed to its easy reduction reaction and/or fast dissolution reaction into water compared to that of oxygen.

Weight reduction of automobiles is an effective way to reduce carbon dioxide emissions. To reduce the weight, the adhesion joints of light materials are expected to be widely used. However, the deterioration evaluation for the adhesion joints exposed to corrosive environments such as the salt-damaged area is carried out by destructive evaluation methods like a tensile test.

In this study, to develop a non-destructive method to detect the deterioration of the Al/CFRP lap joints by adhesive, we investigated the change in the electrical characteristics of the joints before and after corrosion tests by electrochemical impedance spectroscopy. It was found that the impedance and the frequency dependence of the dielectric loss tangent of the joints were changed by corrosion test.