CORROSION RESISTANT SOL–GEL COATING ON ۲۰۲۴-T۳ ALUMINUM

The inherent reactivity of the Al–Cu alloys is such that their use for structural, marine, and aerospace components and structures would not be possible without prior application of a corrosion resistance system. Historically these corrosion resistance coatings were based on the use of chemicals containing Cr (VI) compounds. Silane coatings are of increasing interest in industry due to their potential application for the replacement of current toxic hexavalent chromate based treatments. In this study, hydrophobic coating sol was prepared with methyltriethoxysilane (MTES), methanol (MeOH), and water (as ۷M NH۴OH) at a molar ratio of ۱:۲۵:۴.۳۱ respectively. The coatings were applied by a dip-technique to ۲۰۲۴-T۳ Al alloy, and subsequently cured at room temperature and there after heat treated in an oven at ۱۵۰°C. The anticorrosion properties of the coatings within ۳.۵ wt% NaCl solution were studied by Tafel polarization technique. The sol–gel coating exhibited good anticorrosion properties providing an adherent protection film on the Al ۲۰۲۴-T۳ substrate. The surface properties were characterized by water contact angle measurement, scanning electron microscopy (SEM), and the composition was studied by Fourier transform infrared spectroscopy (FTIR).

Keywords:

sol- gel , Al–Cu alloys , hydrophobic , anticorrosion