The passive oxide films growth on 316L stainless steel in borate buffer solution measured by real-time spectroscopic ellipsometry

• Published in: Applied surface science 2015-10, Vol.351, p.367-373
• Main Authors: Xu, Haisong, Wang, Lu, Sun, Dongbai, Yu, Hongying
• Format: Article
• Language: English
• Subjects: Austenitic stainless steels; Borates; Chromium; Ellipsometry; Heat resistant steels; Iron; Oxide film; Oxides; Passivation; Stainless steel; Stainless steels; X-ray photoelectron spectroscopy; XPS
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.05.165

•The optical properties of passive oxide films on 316L stainless steel were studied.•The thickness of the oxide films (1.5–2.6nm) increased linearly with the potentials.•The growth of passive film followed high electric field ion conduction model.•Selective solubility of oxide induced compositional change of passive film. Passive film growth on 316L stainless steel was investigated in borate buffer electrolyte (pH=9.1) by real-time spectroscopic ellipsometry (SE) and the composition was estimated by X-ray photoelectron spectroscopy (XPS). Anodic passivation of 316L SS was carried out in the potential range from 0VSCE to 0.9VSCE, after potentiostatic polarization for 1800s, the current density decayed from 10−2Acm−2 to 10−6Acm−2. The passive film thickness was simulated from Frenel and Drude reflection equations, the average complex refractive index was assumed to be N=2.3−j0.445. The estimated thickness increased linearly with potential from 1.5nm at 0V to 2.6nm at 0.8V. The growth of passive film followed high electric field ion conduction model. The passive film mainly contained the oxide/hydroxide of iron and chromium. The selective solubility of oxide in passive film explained the change of iron and chromium content at different potentials. Few nickel and molybdenum also contributed to the passive film with a constant content.