ZnO nanoparticles impregnated polymer composite as superhydrophobic anti-corrosive coating for Aluminium-6061 alloy

Abstract

This work emphasizes the preparation, characterization and anti-corrosive behavior of super-hydrophobic (SH) polymer nanocomposite (PNC) coating developed on Al-6061 alloy. The SH nature is achieved on Al-6061 alloy by coating a mixture containing polyvinyl chloride (PVC), copper stearate (CS) and ZnO nanoparticles (Nps). The structural and molecular characterizations of ZnO Nps, CS, PVC, and PNCs are performed employing XRD, FESEM, FTIR, etc. The influence of average roughness of the surface towards the SH behavior achieved by varying the wt% of ZnO Nps from 0.5 wt% to 2.5 wt% has been assessed from the AFM images. The water contact angle of PNC incorporated with 2.5 wt% of ZnO Nps (PNC-5) exhibits 154° which is used as corrosion resistant coating for Al-6061. Potentiodynamic polarization and electrochemical impedance spectroscopic analysis are performed for bare and PNC-5 coated Al-6061 in 3.5 % NaCl as the electrolyte. The corrosion rate of Al-6061 is decreased from 23.75 mpy to 0.2253 mpy while coating PNC-5. Important parameters such as corrosion protection efficiency, corrosion current density, polarization resistance, charge transfer resistance, double layer capacitance, etc. are evaluated and found that the air trapping phenomenon of SH surface is responsible for the effective corrosion resistance behavior.