Corrosion protection of aluminum alloy 7075 using functionalized micro- silica based epoxy coatings

Abstract

Composite coatings were prepared by using epoxy-hardener having a 2:1 composition and functionalized SiO _2 having 0, 0.01, 0.03, and 0.05 proportion/s accordingly. Curing of the coatings on aluminium alloy 7075 substrates was performed at a temperature of 60 ± 5 °C. Moreover, corrosion assessment was carried out in 0.6M NaCl solution at room temperature. The outcome of Fourier Transform Infrared Spectroscopy (FT-IR) confirmed the presence of Si-O bond and epoxide peaks. XRD spectra depict that the intensity of AA-7075 peaks was substantially effected possibly due to more x-rays absorption in composite coatings as a result of increasing silica content. Electrochemical Impedance Spectroscopy (EIS) analysis depicted 116, 284, 620, and 1309% increase in charge transfer resistance (Rct) for 0, 1, 3, and 5% silica composition relative to bare AA-7075 samples. Moreover, potentiodynamic plots were used to estimate corrosion rate which depicted decline of 20, 55, 40, 90 and 97% when compared with pure AA-7075 substrate.

Keywords

• aluminum alloy 7075
• functionalized micro-silica
• corrosion protection
• EIS
• composite coatings