著者

日根 文男 保田 昌樹

出版者

公益社団法人 電気化学会

雑誌

電気化学および工業物理化学 (ISSN:03669297)

巻号頁・発行日

vol.39, no.6, pp.530-535, 1971-06-05 (Released:2019-11-18)

被引用文献数

1 1

著者

保田 昌樹 日根 文男

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.31, no.340, pp.22-27, 1982-01-15 (Released:2009-06-03)

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Formation of corrosion tubercles on carbon steels were carried out in the aerated neutral solutions composed of boric-borate buffer (0.01M) and water with some suspensions of CaCO3 and CaSiO3 powders at pH=7.5-8.8. The solutions containing NO2-, CrO42-, or HS- of less than 50ppm in concentration were also examined. The solution temperature was at 60-65°C.The tubercles thus formed were classfied into three types: the active passive, the general corrosion, and the sulfide initiative, depending on the potential. The active passive-type tubercles formed at the potential range where the second peak of current appeard on the anodic polarization curve. On the other hand, the general corrosion-type tubercles grew at the potentials where general corrosion of steels tested appeard. In the latter case, calcium scale deposited on the steel surface, but the corrosion spots formed partially at which the scale deposition was insufficient.The mechanism for the sulfide initiative-type tubercles is unclear whereas it forms certainly in aerated and neutral solutions containing HS- at the potential range -0.50 to -0.55V vs. Ag/AgCl.

著者

日根 文男 保田 昌樹

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.20, no.211, pp.523-526, 1971-04-15 (Released:2009-06-03)

参考文献数

9

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The disturbance of electric field in the vicinity of the test electrode by the Luggin-Haber capillary was studied mathematically and empirically with the current interrupter. The equipotential line near the capillary tip was predicted, and considerable deformation was observed over about one third of the diameter of the capillary. The capillary located close to the surface of the test electrode disturbed the uniform current distribution, and the build-up curve of the oscilloscope trace was deformed. Its critical distance was about twice the diameter of the capillary.

著者

日根 文男 保田 昌樹

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.23, no.251, pp.654-659, 1974-08-15 (Released:2009-06-03)

参考文献数

20

被引用文献数

4 8

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It is well-known that the corrosion rate of iron and steel is affected by the Fe3+ concentration in acidified solutions. Experimental works on oxidation from Fe2+ to Fe3+ by the dissolved oxygen in various electrolytes have been carried out. Generally, the process is first order with respect to Fe2+, and it depends much on the pH. The reaction rate increased with decreasing pH in HCl, while the rate decreased with decreasing pH in other solutions such as phosphate, sulfate and citrate buffer solutions. The reaction rate was less than 10-3min-1 in solutions of pH<4, or the increment of Fe3+ was only 10-5M/min in solutions containing Fe2+ of 10-2M. The limiting current density for the cathodic process of those Fe3+ to Fe2+ would be 1.6×10-5ma/cm2, which is very small in comparison with the corrosion rate of Fe in aerated solutions. Therefore, it is concluded that the effect of oxidation of Fe2+ by the dissolved oxygen is negligible on corrosion of iron and steel.