Development of poly(vinylcarbazole)/alumina nanocomposite coatings for corrosion protection of 316L stainless steel in 3.5% NaCl medium

Abstract

Poly(vinylcarbazole) (PVK) and PVK-alumina (Al 2 O 3 ) nanocomposite coatings were electrochemically coated on 316 L stainless steel (SS) substrates for corrosion protection of 316 L SS in 3.5 weight (wt) % NaCl medium. The formation of PVK and incorporation of nanoalumina particles in PVK-Al 2 O 3 nanocomposite coatings were confirmed from attenuated total reflectanceinfrared spectroscopy (ATR-IR). Thermal analysis (TG) results showed enhanced thermal stability for the composites relative to PVK. Incorporation of Al 2 O 3 nanoparticles enhanced the micro hardness of PVK coated 316 L SS. The dispersion of alumina nanoparticles was examined via scanning electron microscope (SEM) and tunneling electron microscopy (TEM) and revealed distinct features. The influence of nanoparticles on the barrier properties of PVK and PVK-Al 2 O 3 nanocomposites was evaluated in aqueous 3.5 wt % NaCl by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies. The results proved that PVK nanocomposite coatings provided better protection for 316 L SS than PVK coatings. The drastic increase in impedance values is due to the high corrosion resistance offered by the PVK nanocomposite coatings that arises due to the interaction between Al 2 O 3 nanoparticles and PVK. The highest corrosion protection shown by the 2 wt % nano Al 2 O 3 incorporated PVK composite coatings proved enhanced corrosion resistance compared to PVK.

Synthesis and Anticorrosive Properties of Novel PVK-ZrO₂Nano Composite Coatings on Steel-Substrate

“…The nature of the current change varied significantly as the ZrO 2 nano particles were introduced into the coating electrolyte. Thus, compared to the PVK [5], the current density decreased for all the composites. The decrease in current density is attributed to the influence of nano ZrO 2 particles and its varying wt.% and henceforth the polymer growth and morphology.…”

“…2. It is compared with the IR data of our previous finding with respect to the synthesis of PVK [5] (see also Table S1 and Fig. S1 in Supplementary materials).…”

“…The 316L SS samples were passivated in 50 % nitric acid for about 10 minutes and used for electrochemical polymerization. Electro polymerization of vinyl carbazole (VK) on the working electrode (316L SS) was performed with the chronoamperometric technique by applying a constant potential of 1.2 V SCE for 1000 s in ACN with 0.1 M LiClO 4 as supporting electrolyte [5]. All the potentials were measured with respect to SCE electrode.…”

“…Incorporation of metal oxide nanoparticles into the conducting polymers minimizes the penetration of these corrosive ions and enhances the corrosion resistance. In the past, several oxide nanoparticles such as; alumina (Al 2 O 3 ) [5], manganese dioxide (MnO 2 ) [6], vanadium pentoxide (V 2 O 5 ) [7], titania (TiO 2 ) [8], ferric oxide (Fe 2 O 3 ) [9], tungsten oxide (WO 3 ) [10], zinc oxide (ZnO) [11], silica (SiO 2 ) [12] and zirconia (ZrO 2 ) [13] were incorporated into CP matrix and its corrosion protecting ability was explored. For instance, poly (o-toluidine) /ZrO 2 nanocomposite coating was effective to control the corrosion rate of mild steel [14].…”

“…% NaCl medium. The results of this work were compared with our earlier work to elucidate the properties of the PVKZrO 2 nanocomposite coatings and the effect of varying weight ratio of ZrO 2 nanoparticles [5].…”