Development of a Self-healing Corrosion Protection Coating System for High Strength Aluminium Alloys
The overall goal of this thesis is the development of a chromate-free self-healing corrosion protection system for high-strength aluminium alloys. The concept of the approach is based on inhibited sol-gel coatings as a pre-treatment and inhibitor loaded microcapsules incorporated in the paint film. The objectives are the design, development, and validation of this new protection concept. The active and passive corrosion protection properties and the involved inhibition mechanism have been studied using electrochemical test methods. The results were proven by comparison with conventional tests. The stabilisation of the aluminium/coating interface in the new protection system is found to be superior compared to existing chemical conversion coatings and commercially available sol-gel coatings. Encapsulation of corrosion inhibitors has been demonstrated to provide an economic way of combining effectiveness and compatibility of corrosion inhibitors with organic paint primers. The capsule doped primer confers active corrosion protection on macroscopic defects in the coating system.