Fabrication of superhydrophobic titanium dioxide coating on AISI 316L stainless steel by electrophoretic deposition and using trimethoxy(propyl)silane modification

A superhydrophobic TiO 2 /TMPSi (trimethoxy(propyl)silane) composite coating was deposited on AISI 316L stainless steel using a two-step process: 1) Electrophoretic deposition (EPD) of TiO 2 nanoparticles (P25) from a colloidal suspension of TiO 2 in acetylacetone with the addition of iodine. 2) Dip coating using different concentrations of TMPSi in aqueous ethanol solution. Wettability of the surface was determined by WCA and SA measurements. The WCA and SA of the optimum sample (1.5 vol.% TMPSi) were equal to 160.1° and 3.7° respectively. Surface morphology was investigated by FESEM and nano/micro roughness on the surface was observed and the hydrophobicity can subsequently be related to this roughness. Furthermore, the surface cracks were eliminated by swiped applied potential in the EPD process (from 5 V to 30 V) and drying under controlled temperature. The crack elimination process due to the decrease in surface roughness led to decrease in WCA and SA (i.e. WCA=150°, SA=5.6°).