Investigation of Corrosion Resistance and Mechanical Behavior of Super hydrophobic Surface on Aluminum Alloy 6061

Abstract

Corrosion of metals is a serious issue and to overcome corrosion is a big challenge of the century. Conventional methods such as use of inhibitors, coating and cathodic protection have been used. Enthused by nature, super-hydrophobic surfaces are emerging as promising technique to overcome corrosion of metals. Fabrication of super-hydrophobic surface is a novel and cost effective method with very potential results. In this study aluminum alloy 6061 has been used, which is most common material used in marine vessels. Marine vessels are subject to corrosion in sea water Corrosion resistance and mechanical behavior of super-hydrophobic alloy has been investigated. Initially aluminum alloy was grinded using different grit size sand papers and cleaned with acetone and de-ionized water respectively. Effect of anodization parameters such as voltage and time were investigated. Samples were anodized at 3,5 and 8 volts. Anodization time was varied from 30 to 120 minutes. Electrolyte solution for anodization was mixture of H2SO4, oxalic acid and NaCl. To obtain super-hydrophobicity, anodized samples were coated with polypropylene. Results showed that best hexagonal pores were obtained when sample was anodized at 8 volt for 90 and 120 minutes with highest wet contact angle of 161o. Surface morphology and topography was investigated by Scanning Electron Microscope and Atomic Force Microscope. Presence of different elements was confirmed by Energy Dispersive X-ray analysis and X-ray diffraction peaks determined the crystallinity of aluminum alloy 6061. Corrosion resistance of aluminum alloy 6061 in sea water was employed by potentiodynamic scan and linear polarization resistance. Investigations revealed that with increased anodizing time and voltage, corrosion current density and corrosion rate decreased drastically. Linear polarization resistance measurements exhibited considerable raise in polarization resistance (Rp). x Corrosion efficiency of prepared super-hydrophobic aluminum alloy enhanced with increased anodizing time and voltage. Mechanical behavior of super-hydrophobic aluminum alloy 6061 was evaluated by micro-hardness test after polypropylene coating. Results revealed that super-hydrophobic coating was not affected by applying force on the surface.