The corrosion of 316L stainless steel was examined in a high-temperature and high-pressure methanol solution containing chloride ions as decomposition system reactor material using subcritical or supercritical methanol. Surface morphology of corrosion reactions on the sample immersed in a deaerated or aerated anhydrous methanol solution containing 0.53 wt% LiCl at 323 - 473 K were observed. Below 423 K, pitting corrosion was observed in all methanol solutions. On the other hand, at 473 K, pitting corrosion was not observed in spite of higher temperature. The results of electrochemical impedance spectroscopy and cathodic polarization measurements in deaerated methanol solution revealed that the cathode reaction was reduction of proton derived from the dissociation of methanol at high temperature and that the nature of the passive film varied during immersion in the methanol solution. Based on the result of XPS C1s spectra, it is suggested that passive film formed in the methanol solution was composed of the decomposition products of methanol.

Subject
Electrochemical impedance spectroscopy, Decomposition, Materials, Passive films, Chloride solutions, X-ray spectroscopy, Pitting, Immersion, Corrosion resistance, Methanol, Stainless steel, Risk reduction, Corrosion potential
Keywords:
316L Ss, pitting corrosion, high-temperature and high-pressure methanol solution
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2008
Association for Materials Protection and Performance (AMPP)
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