The electrochemical behaviors of high temperature oxide film formed on the sputtered microcrystalline coating of M38 alloy (mc-M38) were investigated by potentiodynamic and electrochemical impedance spectroscopy (EIS) techniques in 3.5% NaCl solution. Mott-Schottky analysis was used to study the semi-conductive properties of the surface oxide. The results of the capacitance measurements showed that the oxide films on both the coating and the cast alloy were p-type semiconducting characteristics. Both the carrier density (N-a) and the flat band potential (E-fb) were obviously frequency-dependent, and the optimal frequency range was from 1000 to 1500 Hz. The oxidized coating exhibited higher protectivity than the oxidized cast alloy due to the lower carrier density compared with that of the oxidized cast alloy. The EIS data of the long-term immersing tests suggested that the oxide film served as an inner-barrier layer against chloride ions. The penetration of the aggressive ions into the surface oxide resulted in the decreased polarization resistance as a function of the immersion time.
部门归属
chinese acad sci, met res inst, state key lab corros & protect, shenyang 110016, peoples r china.;fang, fh (reprint author), chinese acad sci, met res inst, state key lab corros & protect, shenyang 110016, peoples r china;fhwang@imr.ac.cn
H. P. Bai,F. H. Fang. Protective properties of high temperature oxide films on Ni-based superalloys in 3.5% NaCl solution[J]. Journal of Materials Science & Technology,2007,23(4):541-546.
APA
H. P. Bai,&F. H. Fang.(2007).Protective properties of high temperature oxide films on Ni-based superalloys in 3.5% NaCl solution.Journal of Materials Science & Technology,23(4),541-546.
MLA
H. P. Bai,et al."Protective properties of high temperature oxide films on Ni-based superalloys in 3.5% NaCl solution".Journal of Materials Science & Technology 23.4(2007):541-546.
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