Electrochemical measurements for titanium in 2N, 1N and 0.5N H₂SO₄ containing various amounts of dissolved oxygen were carried out. The rest potential of titanium shifted in the positive direction with increasing oxygen content in solution, but it did not depend on the concentration of H₂SO₄ at the limit of zero oxygen concentration. The above fact suggests evidence for the dissolution mechanism involving {Ti(III)H}_ads as an intermediate. It was confirmed from the measurements of anodic and cathodic polarization that the titanium surface was covered by oxide even in the active corrosion region. The coverage of oxide on the surface increased as the electrode potential was raised. The anodic polarization curve of titanium in the solutions containing no oxygen was shown to be obtained by extrapolation for the solution to zero oxygen concentration.

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In order to clarify the role of the bound water in the passive film to the stability of AISI 304 stainless steel in chloride media, precise measurements of the induction period of pitting and the frequency of the anodic current fluctuation were made, and the effect of desorption of the bound water from the passive film with heat treatment and dioxane treatment on the induction period and the anodic current fluctuation was investigated. From the results it was deduced that the passive film has two different kinds of bound water depending upon the condition under which the film is formed. These two kinds of water are characterized as follows; (1) The bound water in the passive film formed under the passivation conditions at low temperature or at low potential (the first kind of bound water) is easily dehydrated by dioxane solvent, and is active to chloride ions as well as to film formation. (2) The bound water formed at high temperature or for long time of passivation (the second kind of bound water) is not easily transferred to dioxane media. It is substantially incorporated in the passive film. (3) The first kind of bound water has the tendency to change into the second kind of bound water.

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Durability and applicability of various types of tungsten bronzes, Na_xWO₃, (Na-K)_xWO₃, and (Na-Cs)_xWO₃, for the inert electrode or catalytic electrode were examined in chloride-containing acidic media by means of polarization measurement, electronmicroscopic observation, activation by noble metal and chemical analysis. Tungsten bronzes of the composition with x ranging from 0.5 to 0.9 were synthetized by fused salt electrolysis of mixtures of Na₂WO₄+WO₃ with or without addition of KOH and CsOH. Cyclic linear sweep voltammgrams of tungsten bronzes in saturated Na₂SO₄ solution (pH=0) show that the anodic current begins to flow at the potential of ca. 1.5V SCE for sodium tungsten bronze (x=0.91), while practically no current flows up to 4.0V (SCE) for Na-K or Na-Cs tungsten bronzes. These mixed tungsten bronzes are thus very resistant against anodic polarization. Addition of NaCl to the media increased anodic polarization and shifted the curve to more noble direction. Tungsten bronzes activated by RuCl₃ treatment show anodic polarization behavior completely different from that mentioned above. Anodic current flows at almost their reversible potentials of Cl₂/Cl^- or O₂/H₂O redox systems. Electronmicroscopic observation of the surface of tungsten bronzes after prolonged electrolysis in chloride-containing media reveals a trace of corrosion, which is also confirmed by colorimetric analysis of dissolved tungsten in the electrolyte used for extended time.

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The vapor phase rust-inhibiting papers, powders, tablets and oils were prepared of hexamethylenetetramine (HMT) as a vapor phase rust-inhibitor with various sub-components. Their rust-inhibiting effects for zinc were investigated and the rust-inhibiting mechanism was discussed. The results are summarized as follows: (1) Milk casein as a binder for a vapor phase rust-inhibiting paper exhibited better rust-inhibiting effects than polyvinyl alcohol and gum arabic. The effect was excellent when the content of milk casein was larger than 9%. The good effect would be resulted from the water-proof property of casein. (2) HMT should excellent rust-inhibiting effects in the forms of papers, tablets and oils, whereas it gave no good effect in the form of powder, since the extender contacted directly with the surfaces of zinc test pieces. (3) The surfaces of zinc test pieces were corroded slightly in the rust-inhibiting test of HMT, under a severe condition of test for 4 months at 40°C and 100% R. H., but corroding specks were so slight as not to be identified by x-ray diffraction. (4) The rust-inhibiting effect of HMT is superior to that of DICHAN, and the following mechanism was supposed. Since HMT is hygroscopic, it reduces the moisture in the sealed atmosphere, and it decomposes on absorption of water. Formaldehyde, one of the decomposition products, prevents the zinc surface from being corroded and ammonia, another product, gives an atmosphere-controlling effect by neutralizing acidic substances in the sealed atmosphere.

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