Effect of surface orientation on dissolution rate and surface dynamics of UO2 single crystals in nitric acid

• Published in: Corrosion science Vol. 176; p. 109020
• Main Authors: Bertolotto, Solène, Szenknect, Stéphanie, Lalleman, Sophie, Magnaldo, Alastair, Raison, Philippe, Odorico, Michael, Podor, Renaud, Claparede, Laurent, Dacheux, Nicolas
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.11.2020; Elsevier BV; Elsevier
• Subjects: A. TYPES OF MATERIAL: Acid solutions, ceramic; B. TECHNIQUES: SEM, AFM, XRD, ICP-OES, ICP-MS; C. PROPERTIES AND PHENOMENA: Acid corrosion, pitting corrosion, kinetic parameters; Chemical Sciences; Crystal structure; Crystallography; Dissolution; Material chemistry; Nitric acid; or physical chemistry; Orientation effects; Room temperature; Single crystals; Surface dynamics; Theoretical and; Uranium dioxide; C. PROPERTIES AND PHENOMENA: Acid corrosion, pitting corrosion, kinetic parameters; B. TECHNIQUES: SEM, AFM, XRD, ICP-OES, ICP-MS; A. TYPES OF MATERIAL: Acid solutions, ceramic; kinetic parameters; UO2; Acid corrosion; pitting corrosion
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2020.109020

[Display omitted] •UO2 single crystals with (100), (110) and (111) surfaces were dissolved in 2 M HNO3.•Two successive kinetic regimes were identified during dissolution.•The impact of the initial surface orientation on the dissolution rate was evaluated.•During the first kinetic regime, the dissolution occurred mainly at surface defect sites.•The second kinetic step was attributed to a catalysed dissolution mechanism. UO2 single crystals with (100), (110) and (111) oriented faces were dissolved in 2 mol.L−1 HNO3 at room temperature. The evolution of the topography of the surface was monitored and reliable dissolution rates corresponding to the three crystallographic orientations were determined under controlled hydrodynamic and chemical conditions. The dissolution tests of UO2 polished single crystals showed two different kinetic steps. During the first uncatalysed kinetic regime, the enhanced reactivity of the surface at defect sites was demonstrated. The second kinetic step was attributed to a catalysed dissolution mechanism involving species produced at the solid/solution interface during the first step.