Formation of porous hydrophobic stainless steel surfaces by maskless electrochemical machining

Abstract

Surface topography is an important feature, which directly affects the friction, corrosion and flow characteristics of a workpiece. In this study, a new approach was explored to produce a microporous structure by maskless electrochemical machining (ECM). A rough surface with a microporous structure was created on a stainless steel substrate, and the principle of the micropore formation was investigated. It was found that the microporosity could form, grow and interconnect when the potential of the anodic surface was higher than the pitting potential of the material. The electric field is an important factor, and the surface topography can be altered by changing the electrical parameters. The porous microstructure was observed by laser scanning confocal microscopy. The rough and porous surface, modified with 1-dodecanethiol, exhibits hydrophobic characteristics, with a static contact angle of 137° for water droplets. This is a significant improvement in the wetting properties for stainless steels.

Keywords:

• Electrochemical machining
• Porosity
• Hydrophobic surfaces

Acknowledgements

This research was sponsored by the National Natural Science Foundation of China (grant nos. U1134003, 51205066 and 51205137) and Guangdong Natural Science Foundation of China (grant no. S2011040003991).