Nano-micro structured superhydrophobic zinc coating on steel for prevention of corrosion and ice adhesion

Thin films of zinc have been deposited on steel substrates by electrodeposition process and further functionalized with ultra-thin films of commercial silicone rubber, in order to obtain superhydrophobic properties. Morphological feature, by scanning electron microscope (SEM), shows that the electrodeposited zinc films are composed of micro-nano rough patterns. Furthermore, chemical compositions of these films have been analyzed by X-ray diffraction (XRD) and infra-red (IRRAS). An optimum electrodeposition condition, based on electrical potential and deposition time, has been obtained which provides superhydrophobic properties with a water contact angle of 155 ± 1°. The corrosion resistance properties, in artificial seawater, of the superhydrophobic zinc coated steel are found to be superior to bare steel. Similarly, the measured ice adhesion strength on superhydrophobic surfaces, using the centrifugal adhesion test (CAT), is found to be 6.3 times lower as compared to bare steel. This coating has promising applications in offshore environment, to mitigate corrosion and reduce ice adhesion

Nanosilica-based post-treatment of hardened cement-based materials: The underlying physics

We study here the imbibition of a nanosilica-based product in a hardened cement-based material along with the consequences of the product on transport properties. We use X-ray microtomography to assess the liquid ingress in the cement-based matrix as a function of time. We moreover measure the consequences of the nanosilica treatment on water absorption and chloride penetration. Our results suggest that nano-silica imbibition in cement-based materials involves some deep particle clogging and, in turn, some phase separation in the porous cement-based material. As a consequence, the effective local concentration of nano-silica increases in a clogged zone located between a critical clogging depth and the surface. In this zone, the silica concentration level in the porosity allows for the formation of a physical barrier inside the material, which can, in turn, affect transport properties