Aimed at establishing relationship between oxidation kinetics between C/C-composite materials (CCCMs) and the components from view points of material design, rates of oxidation were observed on 3 carbon fibres, 3 carbon-from-resins and 9 CCCMs from each pair of the fibres and the resins. The rates for the CCCMs were almost identical when the CCCMs were composed of an identical origin, although the consumption during the first half period of the oxidation was seen in the matrix carbon. The rate of a CCCMs was not given by a rule of mixture of those of the components, while the activation energy of the rates was given by one. This is explained by assuming that the oxidation mechanism is inherent to each fibre and matrix carbon, that each mechanism operates independently in the CCCMs, and that the number of the active centre in the CCCMs is controlled by a factor of the fibre. The factor to control the number of the active centre remains, however, to be investigated.
In order to investigate the influence of electrode coating materials on the reproducibility of the polarization curves of stainless steels, the anodic polarization curves of SUS 304 steel and 316 steel with various coating materials were measured in sulfuric acid solution. The results showed that the values of the critical passivation current density and corrosion potential of the steel were sometimes affected when certain materials were used as the coatings, and that the passive current density of the steel was little influenced by coatings. The values of icrit of the 304 steel in 5% sulfuric acid solution increased over ten times of the ordinary values and corrosion potential shifted about 100mV towards negative by use of some kinds of silicone sealant. The degree of the increase depended on not only the concentration of dissolved material (or materials) from the sealant, but also the reactivity of the extracted material. On the other hand, in the test for evaluating the current efficiency of sacrificial aluminum anodes the higher efficiency was evaluated errorneously by the use of a silicone sealant. Since the harmful action of this sealant differed with different products on the market in its power, it is necessary to check the product for having no influence on the measurement. It was presumed that the increase of icrit, together with the improvement of current efficiency would arise from the suppression of hydrogen evolution reaction by the sealant.
Inhibition mechanism of N-substituted anilines has been studied on iron corrosion in a hydrochloric acid solution by polarization measurements [This Journal, 28, 77 (1979)]. According to the linear free energy relationship, it has been concluded that a parameter Ψr, which denotes an effect of resonance structures on adsorption of the inhibitors, decreases in the order, aniline>N-methyl aniline>N, N-dimethylaniline. In this work, adsorption behavior of these anilines on iron in 0.5N HCl was investigated by surface-enhanced Raman scattering (SERS) spectroscopy. SERS spectra of these compounds showed that anilinium ions of the compounds are electrostatically adsorbed on the iron surface and a molecule of N, N-dimethylaniline is chemisorbed in part on the surface by the formation of an Fe-N coordinate bond. It was suggested that anilinium ion is adsorbed parallel to the surface via π-electron interaction and N-methylanilinium and N, N-dimethylanilinium ions are adsorbed in a tilted orientation. These results support the order of Ψr for the N-substituted anilines.
In order to isolate and identify the bacteria adherent to metals immersed in the sea water, investigation was carried out by immersing the several metals (stainless steel, Ti, Cu and Al) in the sea water in Shiogama. The isolated bacteria have been classified 14 groups, which have been identified as Pseudomonads, Flavobacterium, Acinetobacter, Enterobacteriaceae, Moraxella, and Vibrio.