In-situ synchrotron studies of the effect of nitrate on iron artificial pits in chloride solutions: I. On the structures of salt layers

DOI: 10.1149/2.0581506jes

Authors: Weichen Xu (University of Birmingham) , Steven Street (University of Birmingham) , Mahrez Amri (DTU Riso) , Fred Mosselmans (Diamond Light Source) , Paul Quinn (Diamond Light Source) , Trevor Rayment (Diamond Light Source) , Alison Davenport (University of Birmingham)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The Electrochemical Society , VOL 162 (6) , PAGES C238 - C242

State: Published (Approved)
Published: February 2015

Abstract: The effect of nitrate on the salt layers in iron artificial corrosion pits in acidic chloride solutions has been studied using in-situ synchrotron X-ray diffraction. During dissolution in 1 M HCl, there is a salt layer of FeCl2.4H2O on the electrode surface, which is isotropic. With addition of trace nitrate, the salt layer remains FeCl2.4H2O and no nitrate phase is observed, but the diffraction pattern becomes anisotropic, consistent with the formation of platelets with (1 2 0) planes settling horizontally. In nitrate solution containing trace of chloride (0.1 M HNO3 + 10 mM HCl), a salt layer is formed that is isostructural with Co(NO3)2.6H2O, and therefore assumed to be Fe(NO3)2.6H2O. This is the first reported crystal structure of ferrous nitrate. The salt layer is also found to give an anisotropic diffraction pattern, consistent formation of platelets with (0 2 0) planes settling horizontally.

Subject Areas: Chemistry, Materials


Instruments: I18-Microfocus Spectroscopy

Added On: 23/03/2015 11:09

Discipline Tags:

Physical Chemistry Chemistry Corrosion Materials Science

Technical Tags:

Diffraction microXRD