Characterization and structure study of the anodic oxide film on Zircaloy-4 synthesized using NaOH electrolytes at room temperature

• Published in: Applied surface science 2006-08, Vol.252 (20), p.7436-7441
• Main Authors: Li, Juan, Bai, Xinde, Zhang, Dailan, Li, Hongyi
• Format: Article
• Language: English
• Subjects: Anodization; Condensed matter: structure, mechanical and thermal properties; Corrosion protection; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Physics; Polarization curve; SEM; Structure and morphology; thickness; Surface treatments; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; XPS; XRD; Zircaloy-4
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2005.08.091

Thick crystalline zirconium oxide films were synthesized on Zircaloy-4 substrates by anodic oxidation at room temperature in NaOH solution with a stable applied voltage (300 V). The film is approximately 4.7 μm in thickness. The XPS and SEM analysis shows that the film is a three-layer structure in water, hydroxide and oxide parts. The thickness of that order is ∼0.01 μm, ∼1 μm, ∼3.7 μm, respectively. The oxide layer is composed of tetragonal and monoclinic phases with the volume ratio about 0.2. Furthermore, the thick anodic film acts as a barrier to oxygen and zirconium migrations. It effectively protects zirconium alloys against the worse corrosion. An extremely low passive current density of ∼0.018 μA/cm 2 and a low oxidation weight gain of ∼0.411 mg/cm 2 were also observed in the films.