In situ quantification of electrochemical dissolution of hafnium-tantalum alloys in acidic media |
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| Institution: | 1. Department of Dental Materials, School of Dentistry, Research Center of Nano-Interface Activation for Biomaterials, College of Dentistry, Chosun University, Republic of Korea;2. Biomechanics & Tissue Engineering Laboratory, Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, USA;3. Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State University, Columbus, OH, USA;1. Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada;2. Canadian Light Source, University of Saskatchewan, 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada |
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| Abstract: | A thin film hafnium-tantalum combinatorial library with a compositional spread of over 70 at.% was used for electrochemical dissolution experiments in nitric acid. Surface microstructure analysis and crystallographic characterization of individual Hf–Ta alloys confirmed a hexagonal to tetragonal transition from pure Hf to pure Ta accompanied by a change in the surface grain structure. A flow-type scanning droplet cell microscope coupled to downstream analytics was used for the quantification of Hf and Ta dissolution rates along the entire compositional spread. Potentiostatically applying 3 V vs. SHE for 120 s for an electrolyte flow of 0.46 ml min? 1 resulted in dissolution rates of pure Hf and pure Ta in the ng s? 1 cm? 2 and pg s? 1 cm? 2 range, respectively. For both species, the average dissolution rate was independent of the compositional gradient, indicating a dissolution enhancement of minor species. A decrease in their activation energy for dissolution triggered by a surface energy modification was the reason for the observed behavior. |
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