Institute of Surface Science
Plasma electrolytic oxidation (PEO) coating. Photo: Hereon
The Institut of Surface Science develops fault-tolerant anti-corrosion coatings which remain effective even when subjected to mechanical damage as well as coatings for magnesium-based medical implants that dissolve in the body according to a set timetable. Although magnesium is not a precious metal, magnesium-based materials are corrosion resistant when exposed to air. In fact, protection against corrosion is only necessary when they are exposed to aggressive media such as sea water or a saline, humid atmosphere. A special care about protection of magnesium should be taken when it is used as a part of multi-material system being joined — by means of welding, for example — to other, more precious metals. Therefore development of active multi-functional coatings for hybrid-structures is one the main focus of WZK.
In addition to corrosion, mechanical loads can also lead to sudden failure when components crack due to stress corrosion or corrosion fatigue. Such failures, the nature of which the WZK department is currently investigating, are caused by hydrogen, which is the primary product of magnesium corrosion.
Simulated current distribution around an electrolyte-wetted Mg-Al mixed compound (Al-rivet in a Mg-sheet). Photo: Hereon
The Corrosion and Surface Technology department (WZK), headed by Prof. Mikhail Zheludkevich, studies the corrosion mechanisms of different light-weight metallic systems with special focus on Mg alloys. The main goals of WZK are dedicated to development of new alloys with tailored corrosion resistance as well new corrosion protection concepts for Mg components or multi-material structures. A novel concept of flexible functionalization of coatings via introduction of active nanocontainers, which are able to store the active functional agents and release them on demand in the presence of suitable triggers, is followed.
The knowledge gained on the corrosion control of structural systems is transferred to the metallic bio-materials and potential battery application. The corrosion related phenomena are studied using the local electrochemical and analytical techniques at different scales being supported by the multi-scale modelling approaches.