Preparation of Superhydrophobic Coating on 5083 Aluminum Alloy for Corrosion Protection in Simulated Marine Environment Containing SRB

In this report, the pitting corrosion behavior of the 5083 aluminum alloy under 3.5% NaCl solution and microbial corrosion environment was studied. The microstructure of the 5083 alloy before and after sulfate-reducing bacteria (SRB) influenced corrosion was characterized by optical microscopy (OM), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS) analysis. The result showed the pitting corrosion rate of the alloy was increased by nearly 7 times from 3.5 wt % NaCl solution to SRB-containing environment, which was indicated by a surface corrosion pit size of 1.06 microns for aluminum alloy in 3.5 wt % NaCl solution environment, and a surface corrosion pit size of 7.02 microns in SRB-containing environment. To enhance the properties of corrosion resistance, a superhydrophobic fluoro silane coating was prepared on 5083 aluminum alloy. The prepared alloy with coating was analyzed by contact angle measurement, X-ray diffraction (XRD) analysis and electrochemistry methods. The superhydrophobic coating, mainly composed of amorphous phase, exhibited good corrosion resistance. The modification of aluminum alloy with superhydrophobic coating increased the AC impedance significantly and shifted the corrosion potential to the positive direction, suggesting the coating has a good protective effect against the aluminum alloy corrosion.