Corrosion inhibition performance of polymer-alloy bilayer coatings: electropolymerised polyaniline and electrodeposited ZnNi with different layer orders

Abstract

Polyaniline (PANI) conducting polymer coatings have been obtained galvanostatically with various current densities (from 0?1 to 0?4 mA cm 22 ) and ZnNi alloy coatings have been obtained galvanostatically at 30 mA cm 22 current density. Corrosion protection performances of monolayered PANI and ZnNi alloy coatings and multi-layered ZnNi/PANI and PANI/ZnNi coatings on st-37 low carbon mild steel (MS) have been investigated by an open circuit potential method, Tafel extrapolation method and electrochemical impedance method in 3?5 wt-% NaCl solution. In addition, the surface morphology of the coatings has been characterised by using scanning electron microscopy (SEM). Synthesising PANI films between two metal layers provided better corrosion protection to the steel. MS/PANI/ZnNi layer formation exhibited the biggest corrosion protection performance among all layer formations of the films and protected MS for up to 72 h.

Optimising parameters for galvanostatic polyaniline coating on nanostructured bainitic steel

“…3 the band A at 1593 cm −1 corresponds to quinoid (Q) ring stretching 38 – 40 and the band (B and C) at 1483 and 1380 cm −1 represent the stretching of the benzoid (B) rings 41 , 42 and C–N stretching in QB-Q surroundings, 37 respectively. The band D at 1252 cm −1 is representative of carboxylic group of the sodium salicylate in the coating 12 . The evidence of the Q and B bands for both the coatings indicates PANI formation on the substrate.…”

“…3 the band A at 1593 cm −1 corresponds to quinoid (Q) ring stretching [38][39][40] and the band (B and C) at 1483 and 1380 cm −1 represent the stretching of the benzoid (B) rings 41,42 and C-N stretching in QB-Q surroundings, 37 1252 cm −1 is representative of carboxylic group of the sodium salicylate in the coating. 12 The evidence of the Q and B bands for both the coatings indicates PANI formation on the substrate. Further, the bands D and E at 1177 and 1023 cm −1 indicate 1-4 substitution on benzene rings, while for bands F-G between 800 and 700 cm −1 were indicative of 1-3 substitutions.…”

“…In recent years, conducting polymers have generated high interest for corrosion protection of metals due to their attractive properties such as corrosion inhibition, 11 , 12 ease of preparation and its high environmental stability 13 . The corrosion inhibiting property of conducting polymers was attributed to the barrier effect and the capability of passivating the metal surface by the redox property of the conducting polymers 14 …”

Electrochemical and computational study of gumexudatesfromCanarium schweinfurthiias green corrosion inhibitor for mild steel in HCl solution

“…In order to get good results, the experiments were carried out in triplicate. From the average weight loss results, the percentage of inhibition efficiency (% IE) and the degree of surface coverage (θ) were calculated using the following equations: [20,21].…”

“…The results of weight loss method were confirmed by estimating total iron ions (Fe 2+ /Fe 3+ ) entered into the test solution during the course of immersion following the method of [21]. The analysis was performed spectrophotometrically using UV/Visible spectrophotometer (Jenway, Model 6405).…”