Anticorrosive performance

The incorporation of copper in electroless Ni-P-PTFE coatings leads to the improvement of corrosion resistance.86 When the copper content in Ni-P-Cu-PTFE coatings was about 6.5%, the anticorrosion performance was the best. The anticorrosion performance of the Ni-P-Cu-PTFE coatings in 1 M HC1 and 20% NaCl solutions was better than that of Ni-P-PTFE coatings or pure Cu. 

M.V. Popa, P. Drob, E. Vasdescu, J.C. Mirza-Rosca, A. Santana-Lopez, C. Vasdescu, S.I. Drob, The pigment influence on the anticorrosive performance of some alkyd films. Mater. Chem. Phys. 

A. Meroufel, C. Deslouis, and S. Touzain, Electrochemical and anticorrosion performances of zinc-rich and polyaniline powder coatings, Electrochim. Acta, 53, 2331 2338... 

PANI/P-PVA (partially phosphorylated poly(vinyl alcohol)) nanoparticles were successfully dispersed in epoxy resin applied to steel [82]. P-PVA is fundamental to obtain a uniform dispersion of PANI nanoparticles, and this fact is responsible for the uniform formation of Fe Oj passive layer at the interface between coating and substrate and therefore for its effectiveness in corrosion protection. PANI was also used in combination with DBSA to be added to epoxy-ester (EPE) system to form a smart anticorrosion coating [73]. DBSA is used as both surfactant and doping agent. By EIS measurements it is deduced that the better anticorrosion performance of PANI (DBSA)/EPE coatings with respect to simple EPE is due to the formation of a second barrier layer by reaction between released DBSA anions and Fe cations at the defective locations of the coating. 

A better anticorrosion performance of the hybrid coatings was observed in comparison to that of neat polymer. This has been attributed to the stronger adhesion strength of the hybrid coatings. The increase in the adhesion strength of the coatings on a cold-rolled steel electrode can be attributed to the formation of Fe—O—Si covalent bonds at the interface of the hybrid coating [230]. 

It is known that conducting polymers provide beneficial protection to various kinds of metals in a corrosive environment [443-445]. Over the past decades, conducting polymers have been considered as the potential candidate for effective corrosion protection without the use of heavy metals. It was found that PPy-clay nanocomposites with low clay loading (e.g., 1.0 wt%) provided an enhanced corrosion protection effect on cold-rolled steel compared with pristine PPy [446]. Similarly, PANI-clay nanocomposites exhibited a better anticorrosion performance than conventional PANI [447]. In the... 

C. I. Eisner, E. Cavalcanti, O. Ferraz and A. R. Di SarU, Evaluation of the surface treatment effect on the anticorrosive performance of paint systems on steel, Prog Org Coat, 2003,48,50-62. 

Common matrix resins for blending with conducting polymers are widely used in traditional anticorrosion coatings, such as epoxy resin [25, 27, 32, 34, 68, 70, 71, 76], polyacrylic-based resin [24, 39, 48, 77, 78], and poly(methyl methacrylate) [30, 60, 62, 64]. The feature of matrix resin as well as the amount of ICPs is important to the anticorrosion performance of conductive composite coating. Samui and Phad-nis [67] blended various amounts of dioctyl phosphate (DOPH)-doped PANI with different polymeric matrices (epoxy resin, polyurethane resin, styrene-butyl acrylate... 

The results were positive and promising. Bagherzadeh et al. [81] found that the anticorrosion performance of a two-component water-based epoxy resin coating system was improved by adding only 0.02 wt% nano-PANI. Ahmad et al. [82] investigated the corrosion protection behavior of waterborne resorcinol formaldehyde (RF)-cured composite coatings of poly(l-naphthylamine) (PNA)/poly(vinyl alcohol) (PVA) on mild steel, and even superior corrosion protective performance was observed in different corrosive media when compared with the reported solvent-based conductive polymer coatings. 

Two-pack etch primers usually contain an anti-corrosive pigment. In traditional formulations, zinc tetroxychromate was used. Current products, however, are mostly chromate-free, in response to environmental pressures. The zinc tetroxychromate has been replaced with a small amount of less toxic anti-corrosive pigments, such as zinc phosphate. Anticorrosive performance may be compromised, to a degree, by such substitutions. 

Table 2.31 Evaluation of Anticorrosion Performances of Duplex Systems After 7 Years... 

Anticorrosion Performance of Microcapsules Containing Composite Coatings... 

In a similar situation, Fedrizzi et al. " found that the anticorrosion performance of polyester organic thin films on low-carbon steel improved owing to pretreatment of the substrate by applying an inorganic zirconia coating, which enhanced the film s adhesion to the substrate. 

Mozafari M, Salahinejad E, Sharifi-Asl S, Macdonald DD, Vashaee D, Tayebi L. Innovative surface modification of orthopaedic implants with positive effects on wettability and in vitro anticorrosion performance. Surf Eng 2014 30(9) 688—92. 

Several approaches have been reported by Hu and coworkers to further improve the anticorrosion performance of electrodeposited silane sol—gel films. They found that adding proper concentration of nitrate ions into the silane deposition solution facilitated the electrodeposition process by reducing nitrate to nitrite, and thus enhanced the corrosion resistance of the films obtained [31]. Co-electrodeposition of silane with silica or titania nanoparticles [47,49], or Ce (N03)s [77], ako improved the films anticorrosion performance. Small content of nanoparticles was foimd to increase the compactness of the electrodeposited silane films. Ce(III) provided a self-healing effect for long-term immersion of the dip-coated Ce(III)-doped bis(triethoxysilylpropyl) tetrasulfide (BTSPS) films in... 

The anticorrosion performance of these coatings assessed by electrochemical impedance spectroscopy shows that the lower impedance was obtained when BTA was directly added to the sol-gel matrix, whereas the best performance was achieved with inhibitor-doped TiO coated with a hybrid film. In terms of active corrosion protection, there is a periodic decrease/increase of impedance associated with the breakdown followed by the self-healing of the intermediate oxide layer. SVET was employed to study the self-healing ability of bi-layer systems at the micro level. The measurements of local corrosion current evolution in the zones of artificial defects have demonstrated well-defined corrosion activity on the sirrface of AA2024 coated with sol-gel film only, while no corrosion activity was revealed even after 24 hours on the alloy treated with a bi-layer system. The reported resirlts show that the adsorbed inhibitor is leached out from the porous... 

Anticorrosive performance of sample-coated CRS coupons can be examined from the values of corrosion potential polarization resistance (Rp),... 

Figure 13.7 shows the Nyquist plots of the PCN. The charge-transfer resistances of samples (a), (b), (c), (d) and (e), as determined by the intersection of the low-fieqnency end of the semicircle arc with the real axis, are 5000, 32 000, 49 000, 58 000 and 89 000 Q cm, respectively. The results clearly demonstrate that the sample with the highest clay loading has the greatest anticorrosive performance. 

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