(93c) Surface Modification of Stainless Steels for Advanced Functionalities

Surface characteristics of stainless steels play a critical role in solid/liquid interfacial phenomena including wetting, fouling, and corrosion, which determine performance of stainless steels for target applications. In this presentation, we describe electrochemical method to control surface topography and chemistry of stainless steel 316L (SS316L), which is one of the most widely used stainless steels, to achieve advanced functionalities in aqueous environments. Potentiostatic polarization in a nitric acid solution was performed to modify SS316L surface properties. Application of a low anodic potential results in a selective grain boundary etching that yields significant microscale topography. With high anodic potential, porous nanoscale topography was achieved. Based upon the potential-topography relationship, hierarchical structure with both nanoscale and microscale features was designed to achieve super-hydrophobic SS316L surface. Nano-textured SS316L surface demonstrated anti-bacterial performance, which can be applied to biomedical devices such as body implants and surgical tools. Improved corrosion resistances of the modified SS316L surfaces were observed, which are attributed to the formation of superior chemical composition at the surfaces during the electrochemical surface modification. These results offer a simple strategy to control surface characteristics and attain/improve functionalities on the metals by using electrochemical method.