Niteen Jadhav

Conducting polymers for corrosion protection: a review

Conducting polymers (CPs) such as polyaniline (PANI), polypyrrole (PPy), and polythiophene (PTh) are used for the corrosion protection of metals and metal alloys. Several groups have reported diverse views about the corrosion protection by CPs and hence various mechanisms have been suggested to explain anticorrosion properties of CPs. These include anodic protection, controlled inhibitor release as well as barrier protection mechanisms. Different approaches have been developed for the use of CPs in protective coatings (dopants, composites, blends). A judicious choice of synthesis parameters leads to an improvement in the anticorrosion properties of the coatings prepared by CPs for metals and their alloys. This article is prepared as a review of the application of CPs for corrosion protection of metal alloys.

In situ preparation and characterization of a conductive and magnetic nanocomposite of polypyrrole and copper hydroxychloride

A nanocomposite of conductive polypyrrole and ferrimagnetic copper hydroxychloride (Cu2Cl(OH)3) was prepared in a single-step via in situ chemical oxidation of pyrrole using CuCl2 as an oxidizing agent. In this study, it was shown that by monitoring the reaction time and conditions, the physical and chemical properties of polypyrrole and Cu2Cl(OH)3 in the nanocomposite can be easily controlled. This resulted in a nanocomposite with optimized conductivity and magnetic properties for a wide variety of applications such as magnetic recording, electromagnetic shielding, sensors, and spintronic devices. The obtained conductivity (0.0006–33 S cm−1) and magnetization (10.25–53.39 emu mol−1) measurements of the nanocomposite were within the range suitable for these applications and were achieved by controlling the reaction conditions and thus the composition of the nanocomposite. With FTIR, XPS and UV-Vis spectroscopy, it was observed that as the reaction proceeds with time under controlled conditions, the oxidation of pyrrole in the presence of CuCl2 leads to significant structural changes in polypyrrole as well as gradual precipitation of Cu2Cl(OH)3. XRD and SEM analysis showed the effect of reaction conditions on the crystallinity and the morphology of the polypyrrole/Cu2Cl(OH)3 nanocomposite. While the chemical and structural variations in polypyrrole were correlated with the conductivity of the nanocomposite, measured via the conductive-AFM technique, the changes in magnetic properties of the nanocomposite were mainly attributed to the variations observed in the crystallinity of Cu2Cl(OH)3.

Tungstate and vanadate-doped polypyrrole/aluminum flake composite coatings for the corrosion protection of aluminum 2024-T3

Polypyrrole (PPy) doped with either tungstate or vanadate as counter anions was synthesized by chemical oxidative polymerization on the surface of aluminum (Al) flakes. This resulted in the deposition of PPy on the surface of the Al flakes leading to the formation of doped PPy/Al flake composite pigments. These composite pigments were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, conductive-atomic force microscopy, four-point probe conductivity, and X-ray photoelectron spectroscopy. Furthermore, these composites were incorporated in an epoxy-amide binder system in order to formulate a primer for an aluminum 2024-T3 substrate. The coatings were exposed to the Prohesion test conditions and corrosion resistance properties were monitored by electrochemical impedance spectroscopy, DC polarization, galvanic coupling, and scanning electrochemical microscopy measurements. It was found that the doped PPy/Al flake coatings provided sacrificial protection to the underlying aluminum 2024-T3 substrate. Additionally, the release of dopants from PPy backbone resulted in the passivation in the defect areas improving the corrosion protection ability.

Synthesis and Characterization of Micaceous Iron Oxide/Polypyrrole Composite Pigments and Their Application for Corrosion Protection of Cold-Rolled Steel

Novel hybrid composite pigments consisting of micaceous iron oxide (MIOX) and polypyrrole (PPy) were synthesized using a chemical oxidative polymerization method and water as a reaction medium. Three different particle sizes (5, 10, and 30 μm) of MIOX, namely, MIOX5, MIOX10, and MIOX30, were used for the synthesis of MIOX/PPy composite pigments. The synthesized hybrid composite pigment was characterized by scanning electron microscopy (SEM) for morphology, energy-dispersive spectroscopy (EDS) for elemental analysis, four-point probe conductivity, and conductive-atomic force microscopy (C-AFM) for conductivity studies. Density tests were also performed for the adhesion between MIOX and PPy. MIOX30/ PPy composite pigment-based coatings were formulated at 15, 25, and 35% pigment volume concentration (PVC) on cold-rolled steel and were exposed to salt spray test conditions according to ASTM B117. Corrosion performance was analyzed by electrochemical impedance spectroscopy (EIS) and anodic polarization. Equiva...

Transport in Protective Coatings

Coatings provide an important role in the protection of metals, whether as an active or passive barrier. One part of the role of coatings is to prevent or delay reactants from the external environment gaining access to the metal/coating interface. Another part is for the timely release of inhibitors to mitigate corrosion. This chapter begins with an examination of transport within coatings particularly oxygen and water and how it is measured. It then examines the influences of composition of the coating through the influence of coating components. It finishes with examination of some recent advances in this area.