Surface and electrochemical corrosion analysis of niobium oxide film formed in various wet media

• Published in: Applied surface science advances Vol. 4; p. 100079
• Main Authors: Chukwuike, V.I., Rajalakshmi, K., Barik, R.C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-06-2021; Elsevier
• Subjects: Corrosion; Effective capacitance; Film thickness; Niobium; Surface analysis; Effective capacitance; Corrosion; Film thickness; Surface analysis; Niobium
• ISSN: 2666-5239; 2666-5239
• DOI: 10.1016/j.apsadv.2021.100079

•Niobium oxide film coatings were formed in H2SO4, HCl, NaCl, and NaOH.•Effective capacitance from the constant phase element and film thickness were calculated.•Niobium corrosion behavior depended largely on the effective capacitance.•Film morphology and thickness are the secondary factors of the protection ability.
Niobium metal has a wide range of applications in medical devices, nuclear applications, and solar cells. Therefore, niobium corrosion behavior and oxide film formation mechanisms are of great interest. Steady-state polarization and a.c transient techniques were employed to determine the effective capacitance, oxide film thickness, and the corrosion behavior of niobium through the time-constant distribution. In this report, we describe a cost-effective wet chemical method of surface treatment of niobium metal for the study of the metastable oxide film (Nb2O5) formed in different media such as NaCl, NaOH, HCl, and H2SO4 solutions. The investigations confirmed a time-dependent formation and dissolution of a protective oxide layer in all the tested media at different potentials, however, recommends short immersion time (<1 h) for H2SO4 and HCl, and > 1 h for NaCl and NaOH. The work developed a new understanding of the niobium corrosion behavior through effective capacitance and film morphology.
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