ホウ酸-ホウ酸ナトリウム緩衝溶液中における鉄さびこぶの発生機構

概要

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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 CaCO_3 and CaSiO_3 powders at pH=7.5-8.8. The solutions containing NO^-_2,CrO^<2->_4, or HS^-,of less than 50 ppm in concentration were also examined. The solutions temperature was at 60-65℃. 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.
社団法人日本材料学会の論文
1982-01-15