This work investigated cathodic disbonding of an unpigmented phenalkamine-cured epoxy coating on mild steel, EC, exposed to 3.5 wt.% NaCl solution. Scanning Acoustic Microscopy (SAM), Scanning Kelvin Probe (SKP), Electrochemical Impedance Spectroscopy (EIS) and optical microscopy have been combined to conduct this study. Several factors affecting the cathodic disbonding process: Film thickness, Cation mobility, Electrolyte concentration, Temperature, Paint composition, Polarisation and Open circuit potential, have been investigated. SAM results show that the disbonding of EC with a linear scribe spreads outwards from the defect with blisters forming at the anodes (as shown in SKP potential maps) within the disbond. The disbonded region does not correspond to complete adhesion loss as verified by peel-testing. Semi-immersion tests show that disbonding under full- and semi-immersion conditions have similar behaviours and both follow parabolic kinetics indicating the disbonding is likely to be controlled by a transport process along the coating/metal interface. An intact epoxy coated mild steel panel coupled with bare mild steel shows that the cathodic reaction beneath the coating obeys Tafel law. A mathematical model simulating cathodic disbonding which produces realistic potential files and shows the oxygen reduction is mostly located near the disbond mouth has been developed.

<p>This master thesis in physics mainly treats Auger spectroscopy of interfaces that has been adhesively bond together with so called controlled delaminating materials (CDM). CDM is a new technology which involves adhesives with the distinctive property that they by the appliance of electricity can be released from a substrate. The reason for using Auger spectroscopy was that it gives a surface sensitive view of the chemical composition of the samples examined and this was believed to give hints of the mechanisms behind loss of adhesion. The samples were so called laminates which is an aluminium foil, CDM adhesive, aluminium foil structure. As expected Auger spectroscopy produced some promising results, especially regarding the breakdown of a certain anion contained into the examined CDM adhesive. This awoke new questions regarding how this anion was decomposed and the idea that it could be due to hydrolysis took form. The by far most important result within this work is that the anion breaks down. This could lead to the formation of hydrofluoric acid if this breakdown in fact is due to hydrolysis and the hydrofluoric acid could then react with the aluminium causing loss of adhesion. This could be the good starting point of a continuing work on CDM.</p>

This master thesis in physics mainly treats Auger spectroscopy of interfaces that has been adhesively bond together with so called controlled delaminating materials (CDM). CDM is a new technology which involves adhesives with the distinctive property that they by the appliance of electricity can be released from a substrate. The reason for using Auger spectroscopy was that it gives a surface sensitive view of the chemical composition of the samples examined and this was believed to give hints of the mechanisms behind loss of adhesion. The samples were so called laminates which is an aluminium foil, CDM adhesive, aluminium foil structure. As expected Auger spectroscopy produced some promising results, especially regarding the breakdown of a certain anion contained into the examined CDM adhesive. This awoke new questions regarding how this anion was decomposed and the idea that it could be due to hydrolysis took form. The by far most important result within this work is that the anion breaks down. This could lead to the formation of hydrofluoric acid if this breakdown in fact is due to hydrolysis and the hydrofluoric acid could then react with the aluminium causing loss of adhesion. This could be the good starting point of a continuing work on CDM.