Studies were made on the oxide film formed on aluminum by dipping it in 1mol/l LiOH containing NO₃^-, and the properties of the film were discussed.
It was found that LiOH, NaOH and KOH of 1mol/l had almost the same solvent power for aluminum. However, the solvent power of LiOH was decreased by the addition of nitrates, at which a thick uniform film was formed on the aluminum surface. The film formed by dipping at 70°C for 10min. was about 10μ in thickness and its Hv values measured by micro-vickers hardness tester with 50g load were about 130-190.
A small amount of NH₃ was found by analysis in the bath after the formation of film. It was suggested from this fast that NO₃^-in the bath behaved as an oxidizing agent.
It was supposed by infrared-spectrum that a bonding of Al-OH was evident in the film.

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Anodic oxidation of aluminum in the non-aqueous solution of NMF (N-methyl formamide)-boric acid system was studied and the mechanism of oxide film formation was discussed.
NMF, having dielectric constant of as high as 182, is a high ionizing solvent, which is a promising electrolyte for anodizing aluminum.
Al of 99.99% in purity was anodized in 1mol H₃BO₃ solution at room temperature at constant current density or at constant bath voltage for various periods. During anodizing, samples were slowly moved in the electrolyte by an anode rocker. Light brown colored or often opaque oxide film was formed, which was very hard and very insulating up to 700v.
The presence of organic radicals was proved to be very probable by IR and ESR spectra and DTA analysis, and they were related with the film color.
It was also proved that a trace of water was essential for the normal growth of oxide film. Therefore, the following mechanism was proposed;
6OH^-+2Al=Al₂O₃+3H₂O+6e
and 6HCONCH₃^-+2Al=Al₂O₃+3HCONHCH₃+3CH₃CN+6e

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This paper describes the research on etching mechanism for coating of polypropylene resin. After pre-etching with xylene and etching with chromic-sulfuric acid mixture at 60°C, the resin was examined by weight loss, surface roughness, and crystallinity.
The results of experiments were summarized as follows:
(1) The weight loss by etching increased with the progress of pre-etching time. It was believed that the degree of swelling of the resin surface and the dissolution of small molecules from the surface increased with the increase of pre-etching time. The results revealed that the resin surface was more easily etched by the subsequet acid etching.
(2) In the standard type of polypropylene resin, the curve representing the relation between surface roughness and etching time was found to show a maximum roughness, but the same curve in the plating type of polypropylene resin was found to be linear.
(3) No carbonyl radicals were formed on the resin surface layer etched under the same conditions.
(4) Crystallinity of the resin was reduced by etching, which was assumed to be owing to the cutting of principal chains of crystalline molecules and their dissolution by etching.
(5) The adhesion of the standard type of polypropylene resin was poor owing to the effects of blisters and skips.
(6) The adhesion of the plating type of polypropylene resin increased during the first 60 minutes, and then, decreased with the lapse of time.

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The object of this study was to investigate the effect of coating thickness on the weldability of the steel coated with a shop primer, and finding a shop primer for giving the highest weldability of steel in the T-type fillet welding under the worst welding conditions.
Experiments were conducted on 11 kinds of shop primers giving high weldability of steel in butt welding.
The shop primers employed were as follows: 5 kinds of organic zinc primers, 4 kinds of non-zinc primers, and each one kind of inorganic zinc primer and wash primer.
The coating thicknesses of primers were about 15, 30, and 60μ. Blank tests were conducted on uncoated steel plates for reference.
Arc welding process was conducted with a gravity type arc welder by T-type fillet welding.
Welding operation test, bead appearance test, and T-type fillet weld bending test were conducted on these test pieces.
The results obtained were as follows:
(1) The arc of welding was more difficult to be generated with the increase in coating thickness of primer. The generation became impossible at more than about 30μ in non-zinc primers and a wash primer. Therefore, it was reguired to remove the primers in the arc starting zones for the welding of these coated steels.
(2) The removal of spatter was easier with the increase in coating thickness of primer, but the arc stability, slag detachability, bead appearance, etc. became worse. As the result, the crack sensitivity in bending test became higher. In particular, a kind of organic zinc primer prepared by the combination of an epoxy resin and minium, and a kind of non-zinc primer containing a large quantity of chrome yellow displayed such a tendency.
(3) The welding speed and deposition rate were lower with the increase in coating thickness of primer. In particular, non-zinc primers displayed such a tendency.
(4) In general, the weldability of these steels coated with primers seemed to turn lower at about 30μ of coating thickness in T-type fillet welding process. Therefore, sufficient control of coating thickness of primer was needed in shop coating.

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The total polarization curve of copper electrode in the electroless copper plating bath containing EDTA as a complexing agent had a peak in its cathode current at about-0.9V vs SCE.
In order to clarify the appearance of this peak, the authors studied the effects of bath compositions on local anodic, local cathodic, and total polarization curves by potential kinetic polarization method.
The results showed that pH of the bath had remarkable effects on the local anodic and total polarization curves; and the variations of local anodic polarization curve approximately agreed with those of total polarization curve depending on pH.
As the results, the appearance of the peak was estimated as follows;
(1) In the potential range where formaldehyde is oxidized, the total polarization curve exhibited the polarization characteristic of relatively active copper electrode.
(2) In the potential more negative than the above range, the total polarization curve exhibited the polarization characteristic of inactive copper electrode, by which a part of its surface was oxidized to Cu₂O.
(3) The peak in the cathode current of total polarization curve resulted from its transference from one curve to another at the oxidation potential of formaldehyde.

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The chromium diffusion layer formed on Ni base superalloys is expected to give excellent high temperature corrosion resistance in the heavy oil combustion gas, because it is a chromium rich additive layer.
In order to prove its corrosion resistance, various kinds of high temperature corrosion tests were conducted in electric furnace and heavy oil combustion furnace.
The results obtained were as follows:
(1) Ni base superalloys such as Inco 700, U-500, and Inco X were considerably resistant to V₂O₅, but they showed low resistance in the heavy oil combustion gas containing Na₂SO₄ or large amounts of sulfur compounds.
(2) All these alloys covered with chromium diffusion coatings showed high resistance. Therefore, the chromium diffusion treatment is applied to these alloys as a promising measure of corrosion prevention for the use of blades of heavy oil gas turbines.

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