Functional surfaces using fluid filled nano-capsules in metallic matrix

With the development of new technologies and applications the requirements of the materials is changing. Many systems cannot be immediately stopped to suffer an extern repair. An "automatically autonomously repair" can be crucial for critical functions of an equipment. The initial idea is to use the examples of the nature because the most materials in the nature are themselves self-repairing composite materials. This concept offers to designer an ability to incorporate secondary functional materials capable of counteracting service degradation. The aim of this study is create bio-inspired surfaces with automatically autonomously repair. For this purpose, nano-capsules with a fluid content of diameters between 100 and 500 nm are applied in a modified galvanic process. The capsules are meant to be deposited together with the metal, forming a functional composite coating. The polymeric capsules were produced at the University Duisburg-Essen. As a basic material for the capsule walls, poly-n-butylcyanoacrylate has been chosen since the resulting structure is relatively stable against mechanical or chemical stress. In addition, poly-n-butylcyanoacrylate nano-capsules can be prepared at low costs on a larger scale. These nano-capsules have been generated in an adapted interfacial polymerization approach. For the electrochemical deposition the chemical composition (salts concentration and additives) of electrolytes was changed and combined with nano-capsules suspension. The mechanical properties were tested by wear testes (linear sliding). The analyses of the electrolyte were carried out on galvanostat / potentiostat system with electrochemical voltametric studies. The small size of the capsules allows for the full embedding of the capsules even in thin coating layers while avoiding significant surface defects. Punctual mechanic load on the surface destroys some of the capsules, leading to a limited local release of the liquid content and initiating its desired activity