Electrochemistry in Corrosion Research

This course introduces the basic principles of electrochemistry, focusing on corrosion re- search. It covers the basics of corrosion testing and monitoring techniques, such as linear polarization, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) for rou- tine applications such as rapid screening of corrosion inhibitors, materials selection, failure analysis, corrosion rate measurement, life prediction, evaluation of paints, coatings, elec- troplating, determination of resistance to local corrosion such as pitting and crevice corro- sion and studies of passivating system.

Introduction to Corrosion

The basics of the electrochemical theory of corrosion will be presented: corrosion reactions, electrochemical nature of corrosion, electrode potential (half cells, corrosion cells), electro- chemical kinetics (charge transfer and mass transport control), corrosion in acids, corrosion in neutral solutions.

Module 1 Uniform corrosion rate

The theoretical concepts and the experimental issues underlying the measurement of uni- form corrosion rates using electrochemical methods will be discussed: Tafel extrapolation, polarisation resistance, reference electrodes, galvanostatic and potentiostatic methods, potential drops due to ohmic resistance of the solution, sample preparation.

Module 2: Passivity and localized corrosion

The basics of metals/alloys passivation mechanisms including a short presentation of the most relevant characterization methods (electrochemical/surface analytical) to assess oxide film growth, stability and composition will first be introduced. The passivity breakdown and different localized corrosion propagation mechanisms will then be described. Critical con- trolling factors such as environment and aggressive ion types but also examples of alloying element influence will finally be discussed.

In the second part, concepts and dedicated electrochemical methods/setup related to crev- ice corrosion and aeration cells will be discussed. The theory and measurement of oxygen concentration/diffusion control will briefly be introduced in relation with the lab work.

Module 3

This module will be focused on the method of Electrochemical Impedance Spectroscopy. The basics on AC and DC electronic circuit and how this can be correlated to real electro- chemical cases will taught. It will be based on concrete example to see how to extract prac- tical information on the system, based on impedance measurements. Programing on the NOVA software and the best parameters of the EIS measurements will also be discussed.