Tohoku University · Materials Science
이즈미 무토 교수의 연구실은 스테인리스강의 부식 거동, 특히 불순물 인clusion(예: MnS, CrS)이 피팅 핵형성에 미치는 영향을 전기화학적 마이크로셀 및 마이크로전기화학 기법을 통해 체계적으로 연구하고 있습니다. 주요 연구 방향은 불순물 상의 전기화학적 용해 거동, 피팅 핵형성 메커니즘, 그리고 해양 대기 환경에서의 부식 메커니즘 모델링입니다. 특히, MnS 및 크롬을 함유한 황화물 인클루전의 부식 거동과 그가 피팅 전위에 미치는 영향을 중심으로 한 고해상도 분석을 수행하고 있습니다.
Figures are computed from collected data and may differ slightly.
The electrochemical dissolution of MnS inclusions and pit initiation processes on type 303 stainless steel were investigated by an electrochemical microcell technique. In , the electrochemical dissolution of MnS inclusions started at vs , which was followed by the initiation of a hemispherical and smooth wall pit at MnS/matrix boundary. It was suggested that the dissolution products of MnS inclusions induced the formation of a salt film, which caused localized electropolishing. In NaCl, the onse
MnS and MnO inclusions with a small amount of chromium were obtained by heat-treatments of Type 304 stainless steel at 1353, 1573, and , and the anodic dissolution behavior of the inclusions was investigated using a microelectrochemical technique. In the case of the sulfide inclusions, those with a high dissolution potential were found to provide high pitting potentials in the macroscopic measurements in NaCl. The initiation sites of metastable and stable pits were at the boundaries of the inclu
The anodic dissolution behavior of CrS inclusions was compared with that of (Mn,Cr)S inclusions containing around 10 atom % Cr using a microelectrochemical cell in NaCl solutions. CrS inclusions were resistant to pit initiation compared with (Mn,Cr)S inclusions. The dissolution potential of CrS inclusions was in the transpassive region of stainless steels. Stable pits were initiated in this potential region. (Mn,Cr)S inclusions dissolved in the passive region of stainless steels, providing lower
In order to develop an accelerated corrosion test which simulates the corrosion behavior of stainless steels in a marine atmosphere, modeling of atmospheric corrosion environments were tried. From the measurement of the night and day variation of meteorological data, it was found that the dew-point of outdoor air is approximately constant and humidity depends on an air temperature. The mole fractions of Na+, Mg2+, and Cl- ions in deposited salts on a stainless steel plate specimen exposed to a m
In 1 M NaCl, the pitting potentials of resulfurized Type 304 stainless steel decreased as the temperature increased from 25 °C to 75 °C. The dissolution potential of MnS in 0.1 M Na 2 SO 4 also decreased with increase in temperature. As the macroscale pitting potentials at all temperatures ranged within the dissolution potential range of MnS, the decrease in MnS dissolution potential was critical in determining the decrease in pitting potentials at high temperatures. However, in 1 M NaCl, the mi
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