Concrete structures have played an important role in the improvement of the social matrix so far. Therefore, the deterioration of concrete structures at relatively early stages found during their use has become a serious social problem. The main causes are cracking, neutralization, corrosion of rebar, etc. Investigation for the prevention and protection against the deterioration of concrete structures has been done both from the viewpoints of economics and safety. In this study, we investigated and assessed the corrosion characteristics of galvanizing steel in concrete solutions to establish countermeasures for corrosion prevention of steel rebar. As a result, we obtained the results that zinc reacted with solutions containing chlorides of higher concentration and that the corrosion characteristics for zinc film containing aluminum decreased.
Tribological properties of chromium nitride films deposited by arc ion plating were investigated as a function of surface roughness caused by droplets adhering to the surface, which decreased with an increase in substrate bias voltage during deposition. In a reciprocating type tribological testing of the chromium nitride films with alumina balls in air with no lubrication, a sudden or gradual shift to the low friction coefficient was observed, depending on the surface roughness of the film; the transition to the low friction coefficient was delayed with an increase in the surface roughness of the films. The low friction coefficient was attributed to the Cr2O3: wear debris of chromium nitride films, which is formed on the friction surface of alumina balls. Undulation or protrusions on the films would prevent the Cr2O3 from depositing on alumina balls, resulting in delaying transitions.
The effect of gaseous ozone on the cleanability of 316 L stainless steel was studied using its nonporous particles pretreated with heat-drying at 150°C, heating at 400°C, and immersion in 10% nitric acid. Bovine serum albumin (BSA) was used as the model fouling material. Dried, heated, and HNO3-treated particles showed largely different surface chemical composition and the surface charge density (σapp). Treatment of the above pretreated particles with 0.2% gaseous ozone resulted in decreases in the positive σapp values of the particles, with only slight variations in their surface chemical composition. The saturation amounts of BSA adsorbed (Γsat) on dried particles decreased significantly (P<0.05) after ozone treatment, whereas those on heated and HNO3-treated particles were not changed. These phenomena were correlated with the degree of a decrease in the positive σapp of the particles after ozone treatment. In continuous cleaning in a plug-flow column fed by a 0.1 M NaOH solution, it was indicated that the rate and efficiency of BSA desorption from all the particles increased as a result of ozone treatment. Kinetic analysis showed that significantly smaller proportions of a slower-desorbing BSA molecule and significantly higher values of first-order desorption rate constants were obtained for the ozone-modified particles than for their non-ozone-modified particles (P<0.05). It was indicated that the cleanability of stainless steel particles could be improved by gaseous ozone treatment irrespective of the surface chemical composition of the original particles.
The reaction to deposit the palladium nuclei by reducing the palladium complex adsorbing on the surface of the polyimide resin was examined using alkaline electrolyzed water containing sodium sulfate to which sodium ascorbate was added. As a result, the palladium nuclei could not form when they were used separately. But it has been confirmed that palladium nuclei formed when both of them coexisted. This palladium nuclei could be used as catalytic sites for the electroless nickel plating. The adhesive strength of the plated nickel layer was equivalent to that produced by a commercially available activator.