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Interfacial Phenomena during Salt Layer Formation under High Rate Dissolution Conditions

DOI: 10.1021/jp311666w DOI Help

Authors: Josh Hammons (University of Birmingham) , Alison Davenport (University of Birmingham) , Seyed Ghahari (University of Birmingham) , Mehdi Monir (University of Birmingham) , Jean-philippe Tinnes (University of Birmingham) , Mahrez Amri (Diamond Light Source) , Nicholas Terrill (Diamond Light Source) , Federica Marone (Swiss Light Source) , Rajmund Mokso (Swiss Light Source) , Marco F. Stampanoni (Swiss Light Source) , Trevor Rayment (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry B , VOL 117 (22)

State: Published (Approved)
Published: April 2013

Abstract: Interfacial phenomena occurring during high metal dissolution rates, in an environment with diffusion-limited transport of dissolution products, have been investigated using time-resolved X-ray diffraction (XRD), small-angle X-ray scattering (SAXS) and fast radiography. Time resolved SAXS data reveal that highly anisotropic interfacial X-ray scattering always precedes salt nucleation. The correlation between the interfacial scattering the presence of salt crystals indicates that the interface is between the metal electrode and the concentrated NiCl2 electrolyte and can therefore be interpreted as reflectivity or Porod scattering. Using fast radiography, we show that continued crystal nucleation and growth results in formation of a crystal-containing salt layer, which initially extends far from the interface (>20 μm), until the NiCl2 concentration decreases below saturation. Dissolution of this thick salt layer occurs mainly at the furthest boundary from the interface until, the salt layer thickness decreases to a steady state value, resulting in a steady state limiting current. These results show that the presence of a crystalline salt layer at a dissolving interface causes microscopic roughening which has implications for understanding both the role of salt films in pitting corrosion and electrochemical processing

Subject Areas: Chemistry, Physics

Instruments: I22-Small angle scattering & Diffraction

Added On: 22/04/2013 09:10

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