We studied the preventive effects of paints upon the corrosion of steel pipes caused by high-temperature sea water running at high speed. The phenomenon is usually seen at iron works or electric power plants, etc. The results are as follows:
1) With painted steel panels dipped in NaCl solution ut 60°C, epoxy resin films have the most preventive power.
Especially, the film cured by isocyanate is better in adhesion to metals, hardness, heat resistance and chemical resistance than any other painted films.
2) Epoxy resin films applied with less than three coats of enamel have pin holes reaching the metal surface. These pin holes greatly promote the degradation of the film.
3) The degrading processes of epoxy resin films are represented by means of electric equivalent circuits. It is found that epoxy resin films hardly suffer from deformation.
4) The internal surfaces of 2″ steel pipes were covered with two coats of primer (containing polyamides as curing agent) and two coats of of enamel (containing isocyanates as curing agent).
After one year of practical use, there was no change on the specimens.

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Studies were carried out on the anodic behaviours of stainless steels in HNO₃ containing halogen ions.
The results obtained were as follows:
(1) In HNO₃ solution containing halogen ions, the critical current density in active state was larger than in H₂SO₄ solution.
(2) Of the halogen ions added to HNO₃ solution, the one that had the strongest action in preventing the passivation of metallic Ni was found to be Br^- ion, while for Fe, Fe-Cr, Fe-Ni and Fe-Cr-Ni alloys it was Cl^- ion.
(3) The oxidation action of HNO₃ made Ni and Fe-Ni alloys depolarize, and, thereby, the anodic dissolution of Ni and Fe-Ni was made much easier than that in H₂SO₄ solution. But Fe-Cr alloys which become passive easily were found to become passive as soon as they are set as alloy anodes.
While in the passive state, the oxidation action of HNO₃ had the two effects: one makes the passive film steady and the other inhibits the indirect dissolution reaction as Cr⁶⁺→Cr³⁺+3e^-by Cl^- ion.

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Several corrosion preventing devices for rails and tieplates laid in tunnels were tested at sites, which include cathodic protection of rails in a steam-locomotive section (Utô) and in electrified sections (Sasago, Tanna and Kanmon) and application of protective zinc plates and zinc-rich paint on rail joints in several locations.
As the result of these field tests, the effectiveness of these methods are generally recognized, and some of them have been adopted as practical and effective counter measures.

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合金の分極曲線を単一成分金属の分極曲線から導くことを説明した。不均一な格子分布をもつ混合金属結晶では, 金属組成のある範囲内で活性態における合金の溶解速度は最小の溶解速度を示す主要成分金属の値に近づくのである。このような挙動は均一な格子分布をもつ混晶における化学的侵食と類似している。ここで述べる理論が正確になりたつためには, 含まれている成分金属の自由エネルギーが合金化によって, 本質的に変化しないことを必要とする。
二元合金の分極曲線の極大は, 一方の成分金属の分極曲線の増大する部分と他方の成分金属の減少部分との交点と密接に関係している。不働態域では最小の溶解度を有する酸化物が蓄積して溶解速度を決定するのである。これらの結論をフェライト系とオーステナイト系の不銹鋼の分極曲線とその各成分の分極曲線とを比較して確かめた。さらに, 不働態被膜の成長の機構について二三の特質を明らかにした。活性態, 不働態いずれの状態においても, もしも合金組成を適当に選ぶならば, 合金の溶解は最小の溶解速度をもつ金属によって制御されるのである。

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