Direct Electrosynthesis of Polyaniline–Zeolite Nanocomposite Coatings on ۳۰۴ Stainless Steel and Their Corrosion Protection Performance

چکیده مقاله

Corrosion of metals is an enormous problem throughout the world. Several techniques have been used to protect metals from corrosion. Among them, polymer coatings may be the most widely used technique. Conducting polymer coatings such as polyaniline on 304 Stainless Steel electrodes can be obtained electrochemically and these coatings provide important protective properties against corrosion [1]. Several strategies have been used to increase the effectiveness of polyaniline as an anticorrosive coating on metals. The utility of various nanoparticles, such as ones made from inorganic materials, natural fibers, graphite, and zeolite as additives to enhance the mechanical and barrier performance of polymers has been established [2]. Polyaniline–zeolite nanocomposite coatings were electrosynthesized on 304 stainless steel using the galvanostatic polarization method. These coatings in current densities viz. 1, 2.5, 5 and 10 mA.cm -2 for duration of time of 100 s were tested. The deposition times viz. 50, 70, 150 and 200 s were applied for the current density of 2.5 mA.cm -2 and the corresponding potential transients were recorded. The synthesized coatings were characterized by UV–Vis absorption spectrometry, fourier transform infrared spectroscopy, X-ray diffraction patterns and scanning electron microscopy. Corrosion properties of these coatings were investigated by the potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The potentiodynamic polarization and EIS studies revealed that the polyaniline-zeolite nanocomposite acts as a corrosion protective layer on 304 stainless steel in 0.5 M HCl solution. The corrosion rate was found to be about 53 times lower than that observed for uncoated steel and also the corrosion current values decreased from 83.03 µA.cm -2 for uncoated steel to 1.55 µA.cm -2 for nanocomposite-coated steel under optimal conditions (i=2.5 mA.Cm -2 , t=100s).