Corrosion Protection Of Mild Steel Research Articles

Use of poly(o‐toluidine)/ZrO2 nanocomposite coatings for the corrosion protection of mild steel

AbstractThis study explored the possibility of using poly(o‐toluidine) (POT)/ZrO2 nanocomposite coatings for the corrosion protection of mild steel in a chloride environment. POT/ZrO2 nanocomposite coatings were synthesized on steel substrates through an electrochemical route. These coatings were characterized with cyclic voltammetry, ultraviolet–visible absorption spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray photoelectron spectroscopy. The performance of POT/ZrO2 nanocomposites as protective coatings against the corrosion of mild steel in aqueous 3 wt % NaCl was evaluated with the potentiodynamic polarization technique and electrochemical impedance spectroscopy. The results of this study demonstrate that POT/ZrO2 nanocomposite coatings provide better protection for mild steel against corrosion than pure POT coatings. The corrosion potential was about 0.312 V versus a saturated calomel electrode, more positive in aqueous 3 wt % NaCl for the nanocomposite‐coated steel than the uncoated steel, and the corrosion rate of steel was reduced by a factor of almost 51. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Electropolymerization of 2-Methoxyaniline: Kinetic Studies, Mechanism, Characterization of the Polymer and Applications as Corrosion Protection for Mild Steel in Acid Medium

Electropolymerization of 2-methoxyaniline on platinum electrode in acid medium was carried out under different reaction conditions as temperature, current density, hydrochloric acid, and monomer concentrations with reaction duration time. The initial rate of the electropolymerization reaction is small and the orders are found to be 1.18, 1.25, and 0.88 with respect to current density, HCl, and monomer concentrations, respectively. The apparent activation energy (Ea) is found to be 56.87 kJ/mol. The obtained polymer films are characterized by 1H-NMR, elemental analysis, and IR spectroscopic studies. The mechanism of the electropolymerization reaction has also been discussed. The thermogravimetric analysis (TGA) was used to confirm the proposed structure and determination of the number of water molecules associated with each polymeric chain unit. X-ray and scanning electron microscopic analysis were used to investigate the surface morphology. The corrosion behavior of uncoated and coated mild steel electrode with poly (2-Methoxyaniline) in 1 M HCl at 25°C was investigated potentiodynamically. The various electrochemical parameters (Icorr, Ecorr, and P%) were calculated from Tafel plots for uncoated and coated electrodes. The influence of some coating conditions as duration time, current density of the electropolymerization, and monomer concentrations were investigated. The data reveal that the presence of coated polymer films on the electrode surface increase the cathodic and anodic polarization compared to the uncoated sample.

Polyaniline for corrosion prevention of mild steel coupled with copper

Polyaniline emeraldine base/epoxy resin (EB/ER) coating was investigated for corrosion protection of mild steel coupled with copper in 3.5% NaCl solution. EB/ER coating with 5–10 wt% EB had long-term corrosion resistance on both uncoupled steel and copper due to the passivation effect of EB on the metal surfaces. During the 150 immersion days, the impedance at 0.1 Hz for the coating increased in the first 1–40 days and subsequently remained constant above 10 9 Ω cm 2, whereas that for pure ER coating fell below 10 6 Ω cm 2 after only 30 or 40 days. Immersion tests on coated steel–copper galvanic couple showed that EB/ER coating offered 100 times more protection than ER coating against steel dissolution and coating delamination on copper, which was mainly attributed to the passive metal oxide films formed by EB blocking both the anodic and cathodic reactions. Salt spray tests showed that 100 μm EB/ER coating protected steel–copper couple for at least 2000 h.

Electrocopolymerization of a binary mixture of pyrrole and 2‐amino‐4‐phenylthiazole: Kinetic studies, copolymer structure, and applications as corrosion protection for mild steel in acid medium

AbstractElectrochemical copolymerization of a binary mixture of pyrrole and 2‐amino‐4‐phenylthiazole on platinum electrode in acid medium was carried out. The kinetic parameters were calculated using ex situ microgravimetric and electrochemical data. The experimentally obtained kinetic equations were RP,W = kW [acid]1.16 [monomer]1.85 from microgravimetric data and RP,E = kE [acid]1.1 [monomer]1.9 from the values of the anodic current density using cyclic voltammetry technique. The apparent activation energy was calculated by the two techniques and is found to be 32.55 and 29.6 kJ/mol from microgravimetric and electrochemical data respectively. The monomer reactivity ratios (r1 and r2) were calculated according to Fineman–Ross method and the copolymer structure was determined from the obtained data, which is found to be a block copolymer structure. The applications of the prepared copolymer as corrosion protection of mild steel in acid medium are studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4047–4058, 2007

Protection of mild steel corrosion with Schiff bases in 0.5 M H 2SO 4 solution

Three new Schiff bases, viz., N, N′-ethylen-bis (salicylidenimine) [S 1], N, N′-isopropylien-bis (salicylidenimine) [S 2], and N-acetylacetone imine, N′-(2-hydroxybenzophenone imine) ortho-phenylen [S 3] have been investigated as corrosion inhibitors for mild steel in 0.5 M H 2SO 4 using Tafel polarization and electrochemical impedance spectroscopy (EIS). The three Schiff bases function as good inhibitors reaching inhibition efficiencies of ∼97–98% at 300 ppm concentration. The fraction <theta> of the metal surface covered by the inhibitor is found to increase with inhibitor concentration. Of the three Schiff bases, the S2 shows better efficiency than the other two Schiff bases. The adsorption of the inhibitor follows Langmuir isortherm. Thermodynamic calculations indicate the adsorption to be physical in nature.

Kinetics of the mild steel corrosion protection by polypyrrole-oxalate coating in sulfuric acid solution

Kinetics of the mild steel corrosion protection in 0.1 mol dm −3 H 2SO 4 by polypyrrole coatings have been investigated by the means of electrochemical impedance spectroscopy (EIS), cyclic voltammetry, polarization measurements and linear polarization. It has been concluded that during the initial time of immersion the coating resistance parameters increase which was connected with diffusion controlled dedoping of oxalate anions, simultaneously with hydrogen evolution reaction on polymer and dissolution of iron through polymer pores. Dedoping of oxalate anions from the bulk of the polymer decreases the polymer conductivity which provokes decrease of overall corrosion rate. After ∼40 h, the completely dedoped PPy coating acts as a classical polymer.

Corrosion behavior and thermal stability of electrodeposited PANI/epoxy coating system on mild steel in sodium chloride solution

The corrosion behavior, sorption characteristics and thermal stability of epoxy coatings electrodeposited on mild steel (MS) and mild steel with electrochemically deposited polyaniline (PANI) film were investigated in 3% NaCl solution using electrochemical impedance spectroscopy (EIS) and thermogravimetric analysis (TGA). Electrochemical deposition of PANI film on mild steel was performed from aqueous solution of 0.5 M sodium benzoate and 0.1 M aniline at constant current density of 1.5 mA cm −2. Epoxy coatings on mild steel and mild steel with PANI film were deposited at constant voltage. It was shown that during initial time of exposure to 3% NaCl, PANI/epoxy coating system on mild steel has lower values of pore resistance (obtained from EIS), greater amount of absorbed water and lower thermal stability (obtained from TGA) which indicate more porous structure comparing to epoxy coating on mild steel. During prolonged exposure to 3% NaCl, PANI/epoxy coating system exhibited increased corrosion protection of mild steel comparing to epoxy coating due to the barrier effect of PANI film and the influence of the dissolved molecular oxygen on cathodic and anodic reaction. Differences between corrosion behavior of epoxy coated and PANI/epoxy coated mild steel in acid and neutral solutions has been discussed.

Comparison between polyaniline‐phosphate and polypyrrole‐phosphate composite coatings for mild steel corrosion protection

AbstractPolyaniline, polypyrrole and their composites have been deposited on mild steel electrode from aqueous oxalic acid solution by using cyclic voltammetry (CV) technique. The resulting coatings were characterized by scanning electron microscopy and EDX analysis. The protective performance against corrosion of these coatings is evaluated by using electrochemical impedance spectroscopy (EIS) technique in corrosive solution (3.5% NaCl). Impedance data indicates a noticeable enhancement of protection against corrosion processes. Also, comparison of polyaniline‐phosphate and polypyrrole‐phosphate coatings indicates better corrosion protection with polyaniline‐phosphate coatings.

Corrosion behavior of duplex polyaniline/epoxy coating on mild steel in 3% NaCl

The corrosion behavior and thermal stability of epoxy coatings electrodeposited on mild steel and on mild steel with electrochemically deposited polyaniline (PANI) film were investigated by electrochemical impedance spectroscopy (EIS) and thermo gravimetric analysis (TGA). The aim of the paper was to present new findings on the corrosion protection of mild steel by a duplex PANI/-epoxy coating in 3% NaCI solution and to determine the effect of thin PANI film on the protective properties of the coating. PANI film was deposited electrochemically on mild steel from an aqueous solution of 0.5 mol dm"3 sodium benzoate and 0.1 mol dm"3 aniline at a constant current density of 1.5 mA cm"2. Non-pigmented epoxy coatings on mild steel and on mild steel with PANI film were obtained by cathodic electrode position at constant voltage and stirring conditions. The resin concentration in the electrode position bath was 10 wt.% solid dispersion in water at pH 5.7. The applied voltage was 250 V, the temperature 26?C and the deposition time 3 min. It was shown that thin PANI film could be used to modify the surface of mild steel prior to epoxy coating deposition, due to the increased corrosion protection of a duplex PANI/epoxy coating comparing to an epoxy coating on mild steel in 3% NaCl solution.

Corrosion studies on electrochemically deposited PANI and PANI/epoxy coatings on mild steel in acid sulfate solution

The corrosion behavior of mild steel and mild steel covered by electrochemically deposited (a) polyaniline (PANI) film, (b) epoxy coating and (c) PANI/epoxy coating system in 0.1 M sulfuric acid solution were investigated by electrochemical impedance spectroscopy (EIS). Electrochemical deposition of PANI film was performed from aqueous solution of 0.5 M sodium benzoate and 0.1 M aniline at constant current density of 1.5 mA cm −2. Epoxy coatings on mild steel and mild steel modified by PANI film were deposited at constant voltage. It was shown that thin PANI film had provided good corrosion protection of mild steel in 0.1 M sulfuric acid solution, and could be used for modification of mild steel prior to epoxy coating deposition. The increased corrosion protection of mild steel by PANI/epoxy coating system in the same solution was obtained.

Corrosion Protection of Mild Steel by Formation of Iron Oxide Polybithiophene Composite Films

Polybithiophene (PBT) was freshly electrodeposited on platinum (Pt) and steel electrodes using cyclic voltammetry from 2,2′-bithiophene (BT), electrolyte and acetonitrile (AC). The electrolytes used were LiBF4, LiClO4, LiCF3SO3, Bu4NBF4, Bu4NClO4, or Bu4NCF3SO3. Black to red colored PBT films with metallic lustre were electropolymerized on Pt and steel electrodes with good adherence. The electrochemical properties and the surface morphology of the deposited PBT film depend on the type of ions used during the electropolymerization. It was found that the steel surface was covered with Fe x O y –PBT composite. The results are discussed on the basis of the structural and the electrochemical properties of the electrolyte ions. The presence of PBT–iron oxide composite on the steel surface causes a shift of the pitting potential (E pit) in the positive direction, indicating the inhibitive effect of PBT–Fe x O y composite on the chloride pitting corrosion.

On the Mechanism of Corrosion Protection of Mild Steel with Polyaniline

The protective capacity of solution-cast polyaniline coating systems toward mild steel has been investigated via simple electrochemical polarization techniques. Coatings containing a polyaniline-emeraldine salt species were found to significantly reduce corrosion rates in 0.1 mol dm−3 NaCl and 0.1 mol dm−3 HCl. The nonconducting counterpart, polyaniline-emeraldine base, also provided some degree of protection in the latter medium. Most importantly, the data confirms that an anodic protection scheme cannot operate in such media. The results presented herein support the emerging paradigm that protection stems from the inhibitory properties of the polymer’s dopant species. © 2004 The Electrochemical Society. All rights reserved.

The corrosion protection of mild steel by polypyrrole/polyphenol multilayer coating

Electrochemical synthesis of very thin polyphenol (PPhe) film was achieved on polypyrrole coated mild steel electrode (MS/PPy) and a multilayer coating was obtained, cyclic voltammetry technique was used for the synthesis. The corrosion performance of this multilayer coating and single PPy coating were investigated in 0.05 M H 2SO 4 solution by using electrochemical impedance spectroscopy (EIS), anodic polarization curves and open circuit potential ( E ocp)–time curves were used. It was found that the multilayer coating could provide much better protection than the single PPy coating for corrosion of MS for much longer periods and an efficiency of 98.3% was determined for this coating after 340 h exposure time in corrosive medium. It is proposed that the very thin PPhe film coated on top of PPy coating lowered the porosity and improved the barrier effect of the coating significantly.

Electrochemical synthesis and corrosion behavior of thin polyaniline-benzoate film on mild steel

The electrochemical synthesis and corrosion behavior of polyaniline (PANI) on mild steel from sodium-benzoate solutions were investigated. Thin, adherent, polyaniline films were obtained by anodic oxidation with current densities between 0.3 and 1.5 mA cm −2. During electropolymerization induction period was not observed. The corrosion behavior of mild steel with polyaniline coating in 0.1 M sulfuric acid and 0.5 M NaCl (pH=3) solutions, was investigated by spectrophotometric method and electrochemical impedance technique. The atmospheric corrosion behavior was also investigated. It was concluded that this coatings had provided corrosion protection of mild steel in all mentioned corrosion environments.

Corrosion inhibition of aluminum alloy in chloride mediums by undoped and doped forms of polyaniline

Corrosion inhibition of Al 3003 alloy by pure undoped PANI (emeraldine base) and PANI doped with p-toluene-sulfonic, camphorsulfonic and dodecylbenzenesulfonic acids was investigated. Corrosion resisting properties of PANI coatings with an artificially created hole defect were evaluated by electrochemical impedance spectroscopy (EIS) in aqueous 3.5% NaCl and 0.1 N HCl solutions. The highest corrosion inhibition factor was obtained for undoped PANI being equal to 12 and 4.4 in neutral and acidic media, respectively. The results indicated that corrosion protection of the bare aluminum alloy surface resulting from a defect of the PANI coating is in line with an increase of the thickness of the oxide layer protecting the aluminum alloy surface. The efficiency of corrosion protection of mild steel and aluminum alloy by polyaniline coatings was compared.

Study of polyaniline containing paint for corrosion prevention

Corrosion protection of mild steel was investigated by coating it with paint containing polyaniline-hydrochloride (PANI-HCl) as pigment. Painted panels were exposed in weatherometer chamber, humidity cabinet, salt spray chamber, sea water. Potentiodynamic measurements were also made for finding corrosion current, potential, polarization resistance, etc. Lower loading of PANI-HCl was found to be more effective in corrosion protection compared to others.

Investigation of the electroactivity of polymethylthiophene film for the corrosion protection of mild steel

The protection mechanism of intrinsically conducting polymers (ICPs) is still under discussion. Most of the discussions concentrate on the effect of the redox behavior and electroactivity of ICPs on the corrosion protection. In the present paper it is shown that polymethylthiophene (PMT) films electropolymerized on mild steel, with 2-(3-thienyl)ethylphosphonic acid used as adhesion promoter, show the desired redox activity. The interaction between the PMT film and some conventional coatings, and the influence of the pH of electrolyte, were investigated. It was shown that the electroactivity of PMT film is lost by the interaction with coatings of high nucleophilicity and is markedly decreased by immersion in an aqueous solution of pH 11.

Corrosion Protection of Mild Steel with Polyaniline–Thiokol Rubber Composite Coatings

The anti-corrosion performance of polyaniline-thiokol rubber (PANI/TR) composite coating applied to mild steel samples in artificial brine and hydrochloric acid environments is for the first time evaluated in this paper. The PANI/TR composite -coatings on mild steel were electropolymerized in a nonaqueous solution. EDS, XPS and SEM were concurrently used to characterize the structure, as well as composition of the coating and show that the structure is favorable to the corrosion protection. Both potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) demonstrated that the PANI/TR coating outperforms PANI coating both in the adhesion to the substrate and its corrosion protection, making the free corrosion potential by about 100mV more positive. As a result, the mild steel corrosion was greatly impeded by applying PANI/TR composite conductive polymer coating.

Application of polypyrrole/TiO 2 composite films as corrosion protection of mild steel

This work is a study of the anticorrosion protection of polypyrrole (PPy) on AISI 1010 steel (mild steel) by the incorporation of TiO 2 pigment into the PPy matrix during electrochemical synthesis. The influence of parameters such as stirring, concentration, pH and nature of the electrolyte were investigated. The degree of pigment incorporation into the polymeric matrix with respect to time and current densities of the electrodeposition process were also investigated. The influence on the current efficiencies of the process was evaluated. The morphology of the composite film was studied by scanning electron microscopy (SEM) and the distribution of the pigment within the polymeric matrix by X-ray photoelectron spectroscopy (XPS). The PPy/TiO 2 composite showed a considerable improvement in anticorrosion properties with respect to PPy films after being submitted to salt spray and weight loss tests. These composite films can be applied as a primary coating replacing the phosphatized layers on mild steel.

Polyaniline and polyaniline–thiokol rubber composite coatings for the corrosion protection of mild steel

The anti-corrosion performance of polyaniline–thiokol rubber (PANI/TR) composite coating covered on mild steel exposed to artificial brine and hydrochloric acid environments was evaluated for the first time. The PANI/TR composite coatings were electropolymerized and deposited on mild steel in a nonaqueous solution. EDS, XPS and SEM were all used to characterize the structure as well as the component of the PANI/TR composite coating, which has indicated that its structure would be favorable to the corrosion protection. The results of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) demonstrated that the PANI/TR coating was much better than polyaniline (PANI) coating both in the adhesion to the mild steel substrate and in the corrosion protection. The corrosion potential was about 100 mV more positive for the substrate coated with PANI/TR film than that with PANI. As a result, the corrosion of mild steel can be inhibited greatly by using the PANI/TR composite conductive polymer as a protective layer.