Cyclic durability of adsorption-induced electrochromic（AiEC）color change was investigated for a microvillus-structured indium-nitride （InN）film fabricated by reactive evaporation with a glancing-angle scheme. Cross-sectional observation revealed that the InN film has a microvillus-like nanostructure with column diameter of approx. 200 nm and gap width of approx. 20 nm. The InN film exhibited AiEC behavior in the visible-infrared range with the maximum transmittance change of 58% at 680 nm wavelength. The AiEC lifespan of the microvillus-structured InN film was 2.1×104 cycles with polarization voltages of －1.4 V（cathodic）and ＋0.2 V（anodic）. The InN film degradation was found to occur because of irreversible transformation of InN into indium hydroxide. This reaction was presumed to be induced by permanent bond formation between surface indium atoms and -OH at anodic polarization. Surface area expansion by introduction of the microvillus-like structure provokes not only an improvement of transmittance change, but also rapid degradation of InN.
Stain resistance is a key performance criterion of pre-painted steel sheet used outdoors. The addition of organosilicate to paint is known to prevent a paint film from staining by hydrophilicity. To clarify the mechanisms related to this technology, we investigated the stain-resistance effects of adding organosilicate to paint used for pre-painted steel sheets. We considered them from the point of solid surface tension, which was divided into three force elements: hydrogen bond force, dipole-dipole force, and dispersion force.
Results show that the organosilicate concentrated near the paint film surface, which exhibited good stain resistance. The hydrogen bond force was much stronger than any other force element of solid surface tension on that film before and after the exposure test. Therefore, the adhesion work between water and that film was greater than between the stain and that film.