Effect of Chemical Composition of Tetraethoxysilane and Trimethoxy(Propyl)Silane Hybrid Sol on Hydrophobicity and Corrosion Resistance of Anodized Aluminum

Abstract

The current study indicates the application of three different range of hybrid sols on substrates. The aim was to achieve an optimum chemical composition on the silane- treated surface in terms of hydrophobicity and corrosion resistivity. Two different monomers including Tetraethoxysilane (TEOS) and Trimethoxypropylsilane (TMPSi) formed the hybrid sols. Sol-gel route was selected to enhance the corrosion resistance of the substrate (anodized aluminum). The role of the precursor’s molar ratios on the hydrophobicity was studied using static Water Contact Angle (WCA) and surface Roughness measurement (Ra). Owing to the evaluation by Field Emission Scanning Electron Microscopy (FESEM), a relatively smooth surface was revealed by silane-treated sample with TEOS: TMPSi, 1:0.5 M ratio. The sample prepared by TEOS: TMPSi, 0.5:1 M ratio sol illustrated a higher static water contact angle. To determine the corrosion resistance of the samples, Potentiodynamic Polarization, Open Circuit Potential (OCP) and Electrochemical Impedance Spectroscopy (EIS) measurements were performed using a 3.5% NaCl solution. Samples also were evaluated by Scanning Electron Microscopy (SEM) after seven days immersion in the same condition. According to EIS results, the sample treated in TEOS: TMPSi, 0.5:1 M ratio sol revealed the best corrosion resistance properties and minor deterioration of surface through the SEM micrographs.