Herman Terryn

Combined EBSD and AFM Study of the Corrosion Behaviour of ETP-Cu

In order to increase the sustainability of metals, a more detailed understanding of the corrosion process is of crucial importance. Current literature often considers corrosion as a purely chemical interaction with a nearly exclusive dependence on compositional effects, while ignoring microstructural and crystallographic properties of the metal surface. Some recent literature data, however, suggest an important effect of microstructural elements such as grain size, crystallographic orientation and grain boundary characteristics. The aim of this work is to obtain a better understanding of the relation between the corrosion behaviour of a metal and its microstructural and crystallographic features. Therefore, warm rolled Electrolytic Tough Pitch (ETP-) Cu was immersed in a 0.1 M NaCl and 0.5M Na2SO4 solution and the combination of Atomic Force Microscope (AFM) and Electron Backscatter Diffraction (EBSD) allowed to identify differences in attack for different crystallographic orientations.

On the Role of the Crystallographic Grain Characteristics in the Corrosion Behavior of Polycrystalline Copper

In order to increase the sustainability of metals, a more detailed understanding of the corrosion phenomenon is of crucial importance. In current literature, corrosion is often considered as a purely chemical interaction with nearly exclusive dependence on compositional effects, whilst ignoring the microstructural features of the metal surface. In the present work, results are presented which illustrate both the role of grain orientation and grain boundaries in the corrosion process. To evaluate the grain orientation dependent electrochemical behavior, polycrystalline Cu, was brought into contact with a corrosive electrolyte. Subsequently, the attack was evaluated by measuring the surface with both Atomic Force Microscopy (AFM) and Electron Backscatter Diffraction (EBSD). It was demonstrated that the grain orientation itself did not significantly influence the corrosion kinetics, but, alternatively, that the orientation of the neighboring grains seemed to play a decisive role in the grain dissolution rate. To increase understanding on the role of grain boundaries, a method was developed based on the electrochemical (galvanic) displacement of gold, which is deposited from an aqueous solution on a pure copper substrate. This technique demonstrated its sensitivity to the grain boundary characteristics as far less gold was deposited on special boundaries, such as coincidence site lattice boundaries, as compared to the random high angle grain boundaries.

Importance of Etch Film Formation During AC Controlled Pitting of Aluminium

Over the last decades much research has been dedicated and reported in literature on the Alternating Current electrograining (A.C. electrograining) mechanism and the parameters that change the final pitting morphology of electrograined aluminium. The reason is the increasing industrial demand every year (currently estimated to be 800,000,000 m2/year) for high quality litho-printing and super capacitors for energy storage. Both applications relay on the production of a controlled roughened surface on aluminium foil which can be achieved through A.C. electrograining. In this case pitting is used as a surface treatment for the production of a larger surface area with uniform pits.