Corrosion Inhibition of Aluminium AA2024 alloy by lignosulfonate doped Conducting Polyaniline –Montmorillonite Nanocomposite

G. Gupta, A.S. Khanna, N. Birbilis
IITB-Monash Research Academy, IIT Bombay, India & Monash University, Australia, IN

Keywords: polyaniline, lignosulfonic, montmorillonite, corrosion resistance, AA2024 alloy

Summary:

Corrosion protection of aluminium AA2024 alloys used in aerospace applications is afforded by the use of chromate coatings. Polyaniline have found to be good anticorrosive coating to replace chromate containing coatings which have adverse health and environmental concerns. Conducting polyaniline coating can also protect the vulnerable internals of the aircraft from the electrical thundering effect. In this work, we have synthesized conducting lignosufonate (LGS) doped polyaniline (Pani)-montmorillonite (MMT) nanocomposite via in situ chemical oxidative polymerization of aniline using LGS as dopant with montmorillonite clay in aqueous medium. The morphology and structure of the synthesized particles were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), infrared analysis (IR), thermal and electrical properties by thermogravimmetric analysis (TGA), four probe conductivity meter, respectively. Coating was formulated by ultrasonic mixing of synthesized particles with in polyurethane matrix. Performance of the coatings was evaluated using electrochemical impedance spectroscopy (EIS), contact angle measurement and adhesion test. The average dry coating thickness was found in the range of 20±2 μm. The coating has been found to offer protection more than 100 days in 3.5% NaCl environment.