An electroactive polyurethane coating was prepared through ring opening reaction of epoxy-terminated castor oil-based polyurethane prepolymers with an appropriate amount of an amine-terminated aniline trimer oligomer (AT). A non-electroactive polyurethane coating was prepared by replacing AT with 1, 6-hexamethylene diamine (HDA) as a curing agent. The chemical structure of prepared coatings was fully characterized by a conventional spectroscopic method and their physicochemical PROPERTIES including chemical resistance, hardness and adhesion strength were also evaluated. The electroactivity behavior of the prepared coatings was confirmed by cyclic voltammetry technique. The corrosion protection PROPERTIES of electroactive and non-electroactive coatings (MS) were both measured by Tafel polarization technique and electrochemical impedance spectroscopy (EIS). According to the Tafel result, a considerable reduction in corrosion current (Icorr) and a more positive shift in corrosion potential (Ecorr) were detected for electroactive polyurethane-coated MS in comparison to those for bare and as well as non-electroactive polyurethane-coated MS. The EIS result indicated higher pore resistance (Rp) and consequently higher corrosion protection for electroactive coating in comparison to non-electroactive polyurethane-coated MS. The higher chemical resistance, hardness, and adhesion strength were recorded for electroactive polyurethane coating. Based on recorded data, it was revealed that the prepared electroactive polyurethane coatings not only could prevent the intrusion of corrosion spices onto the metal surface like a hydrophobic polymer coating, but also could enhance corrosion protection efficiency through redox reactions of their oligoaniline moieties with the metal surface.

Herein, an electroplating method has been developed in order to improve the anti-corrosion PROPERTIES of steel. Ni-based compounds to which solid Al2O3 particles have been electrochemically inserted. Nickel-alumina mixtures were deposited on steel substrates from the electroplating bath using different concentrations of Al2O3. The electrochemical corrosion tests of the samples were carried out in two different solutions 0.5 M K2SO4 and 0.5 M NaCl. Structural and morphological analyzes were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled to microanalysis (EDAX) analyses respectively. The electrochemical behavior of co-electrodeposited coatings (Ni-Al2O3) in corrosive solutions was followed using potentiodynamic methods and electrochemical impedance spectroscopy (EIS). The various tests carried out under working conditions revealed that the Al2O3 particles added to the bath have a beneficial effect on the electrochemical behavior of the steel by reducing its tendency to corrosion. In this work, we were also able to determine the optimal concentration leading to significant inhibition of the steel tested. This synthesized and studied concentration related to Al2O3 was evaluated at around 20 g.L-1.

In this work, polysulfide and nano cerium oxide were added to epoxy in order to modify the toughness and corrosion resistance PROPERTIES of epoxy resin. For this purpose, polysulfide in different weight percentages (5-25 wt%) was mixed with epoxy resin. The physical PROPERTIES and corrosion resistance of the coated samples were evaluated by pull off adhesion tests, cupping, electrochemical impedance and salt spray. Results showed that the addition of 10 wt% polysulfide to epoxy, led to increasing corrosion resistance and toughness. Also, by adding different weight ratio of nano size CeO2 (0.5-6 wt%) to the composition of epoxy/polysulfide resin, anticorrosion and adhesion characteristics of the resultant coatings improved. The results showed that the presence of low concentrations of nano CeO2 (about 1 wt%) led to the best anti-corrosion and adhesion PROPERTIES. Results of FESEM test showed that the dispersion of nano CeO2 in the matrix was completely uniform.

In this work, protective PROPERTIES of polypyrrole/polyaniline composite (as a conductive polymer) have been investigated in 3.5% sodium chloride solution via electrochemical techniques (electrochemical impedance spectroscopy, corrosion potential measurements and anodic polarization tests). Polypyrrole / polyaniline composite were deposited on carbon steel substrate by potentiostatic method. The electric capacitance and resistance of the films were monitored with the immersion time to investigate the water permeability of the paint films. Polypyrrole/polyaniline composite had a relatively low permeability and good catalytic behavior on passivation of carbon steel in longer periods. The results showed that the composite had better ANTICORROSIVE behavior compared to homopolymers (polypyrrole and polyaniline).

Epoxy powder coatings containing zinc aluminum phosphate (ZAP) and zinc phosphate (ZP), which are the 2nd and 1st generation of phosphate-based pigments respectively, were applied to the surface of mild steel sheets. The ANTICORROSIVE performances of the coated samples were studied using electrochemical impedance spectroscopy (EIS). Cathodic disbonding resistance and the adhesion performance of the two coating systems were measured by cathodic delamination and pull-off test respectively. The charge transfer resistance and double layer capacitance obtained from EIS revealed the greater ANTICORROSIVE performance of the coating modified by zinc aluminum phosphate compared to the one treated with zinc phosphate. While an electrolyte diffuses in the organic coating, phosphate pigments dissolve and make a passive layer on the surface of mild steel. Due to the more solubility of ZAP in comparison with ZP, the cathodic desbonding resistance and adhesion of the epoxy powder coating containing ZAP were greater than those of ZP-loaded powder coating. The results show that the ANTICORROSIVE performance of the epoxy powder coating containing ZAP is better than that of the epoxy powder coating modified with ZP.

Metal surface coating occupies an important place in the industry. The most important external factor on metal surfaces is corrosion. Corrosion is a natural process that occurs because of a chemical reaction between the metal surfaces and the medium. It causes the degradation of metals. Three methods are used the prevent corrosion. These methods are cathodic protection, anodic protection, and barrier coatings. In this study, it was aimed to develop environmentally friendly corrosion-resistant paint for the barrier coatings, by using zeolite material which has natural characteristics of corrosion resistance. In other words, it was aimed to gain the ANTICORROSIVE effect to the production of corrosion-resistant paint by adding modified natural zeolite to the paint. Microscale zeolite was modified by using lanthanum (III) nitrate, zinc acetate, and magnesium chloride solutions. The best results were obtained with a zeolite size of 0. 8869 μ, m and using a 60% zeolite/solution volume ratio. It can be said from the results of the experiments that,thin zeolite film applications are very successful for corrosion resistance paint production. Modified natural zeolite coatings show a very good ability to protect surfaces from corrosion. The results of these procedures are positive and promising. The best result is obtained by zeolite with size reduction and 60% zeolite/solution by volume ratio. The amount of zinc phosphate was greatly reduced. High and low contents of zinc phosphates have almost the same ANTICORROSIVE effect with zeolite-modified paint formulations. As a result, cation-exchanged zeolites can be considered a safe and efficient alternative to traditional hazardous pigments in protecting steel surfaces.

The present work is devoted to study the Thymus Algeriensis (TA) extracts as antioxidants and green corrosion inhibitors of mild steel (MS) in 1 M HCl medium at 303 K. The extract from aerial parts of Thymus Algeriensis were obtained by distillation and analyzed. Antioxidant activity of methanolic extract of TA was examined by using both DPPH radical scavenging and β-carotene-linoleic acid bleaching and likened with ascorbic acid and BHA (butylated hydroxyanisole) used as reference compounds. Corrosion inhibition of of mild steel (MS) in HCl by ethyl acetate (EATA) and methanol (EMTA) extracts of TA was studied using weight loss and electrochemical techniques. TA extract was found to be a better inhibitor. Indeed, the inhibition efficiency increased with increase EATA and EMTA concentration but decreased with rise in temperature. The variation of inhibitory efficacy with temperature point towards physical adsorption which is supported by the kinetic and thermodynamic parameters derived from the experimental data. Polarization studies show that the EATA and EMTA act as mixed typed inhibitor. Inhibitive effect was afforded by adsorption of the EATA and EMTA components which was found to accord with Langmuir adsorption isotherm.