Kathodische Reaktionskinetik bei der galvanischen Korrosion von Al2024 und CFK

Abstract

For aeronautical applications, the use of CFRP (Carbon Fibre Reinforced Plastics) is becoming more and more important. It is unavoidable that aluminium and CFRP parts get into electrical and electrolytic contact which may cause severe galvanic corrosion problems.<br />It is of vital interest to understand fundamentally and describe quantitatively the processes causing galvanic corrosion in order to predict the corrosion progress.<br />This project was started with the object to investigate the reaction mechanism and the kinetics of the cathodic galvanic corrosion process.<br />Therefore Aluminium 2024 and CFK electrodes were measured in two different chloride concentrations 0.05 mol/L and 0.10 mol/L in a pH-range from 4.0 to 12.0.<br />For the description of corrosion in thin electrolyte films it is necessary to know the kinetic parameters of the several reaction steps.<br />With a rotating disk electrode can adjust the thickness of the diffusion layer. With the obtained mass transport kinetics and data the exchange current density which is independent of the mass transport can be calculated.<br />The measured current density/potential curves were interpreted by the approximation of Levich for the Nernst diffusion layer and the kinetic data according to Tafel were calculated. The hydrogen evolution and the oxygen reduction were identified with measurements under nitrogen. By copper deposition the electric active area of the CFK electrode surface was calculated.<br />