TITLE:
Instantly Investigating the Adsorption of Polymeric Corrosion Inhibitors on Magnesium Alloys by Surface Analysis under Ambient Conditions
AUTHORS:
Lívia M. Garcia Gonçalves, Larissa C. Sanchez, Stephani Stamboroski, Yendry R. Corrales Urena, Welchy Leite Cavalcanti, Jörg Ihde, Michael Noeske, Marko Soltau, Kai Brune
KEYWORDS:
Online Surface Monitoring, Magnesium Alloys, Polymeric Corrosion Inhibitors, Fast Screening of Effective Formulations, Optimization of Application Process
JOURNAL NAME:
Journal of Surface Engineered Materials and Advanced Technology,
Vol.4 No.5,
August
21,
2014
ABSTRACT:
Surface engineering of
magnesium alloys requires adequate strategies, processes and materials
permitting corrosion protection. Liquid formulations containing corrosion
inhibitors often are to be optimized according to the demands of the respective
substrate and following the service conditions during its application. As an
interdisciplinary approach, a combination of several techniques for instantly
monitoring or elaborately analyzing the surface state of magnesium was
accomplished in order to characterize the performance of new adsorbing
sustainable amphiphilic polymers which recently were developed to facilitate a
multi-metal corrosion protection approach. The application of established
techniques like Contact Angle measurements and X-ray Photoelectron Spectroscopy
investigations was supplemented by introducing related and yet faster
online-capable and larger-scale techniques like Aerosol Wetting Test and
Optically Stimulated Electron Emission. Moreover, an inexpensive setup was
configured for scaling the inset and the extent of degradation processes which
occur at local electrochemical circuits and lead to hydrogen bubble formation.
Using these analytical tools, changes of the surface state of emeried AM50
samples were investigated. Even in contact with water, being a moderate
corrosive medium, the online techniques facilitated detecting surface
degradation of the unprotected magnesium alloy within some seconds. In
contrast, following contact with a 1 weight% formulation of a polymeric
corrosion inhibitor, surface monitoring indicated a delay of the onset of
degradation processes by approximately two orders of magnitude in time. Mainly
based on the spectroscopic investigations, the corrosion inhibiting effects of
the investigated polymer are attributed to the adsorption of a primary polymer
layer with a thickness of a few nanometers which occurs within some seconds.
Immersion of magnesium for several hours brings up a protective film with
around ten nanometers thickness.