Preparation of Self Assembled Sodium Oleate Monolayer on Mild Steel and Its Corrosion Inhibition Behavior in Saline water

A self assembled monolayer (SAM) of sodium oleate was generated on mild steel by the dip coating method. Formation of the SAM on mild steel was examined using Infrared Reflection Absorption Spectroscopy (IRRAS) and contact angle measurements. The chemical and anticorrosive properties of the SAM were analyzed using different techniques. IRRAS and water contact angle data revealed the crystallinity and chemical stability of the SAM modified mild steel. The electrochemical measurements showed that the mild steel with the sodium oleate derived SAM exhibited better corrosion resistance in saline water. The effect of temperature and pH on the SAM formation and its anti corrosion ability was explored.

Synergistic effect of colchicine and iodide ions on the corrosion of mild steel in 0.5 M H2SO4

The inhibition behavior of colchicine (CC) on the corrosion of mild steel in 0.5 M H2SO4 was evaluated by electrochemical methods such as potentiodynamic polarization and electrochemical impedance spectroscopic measurements. The inhibition efficiency increases with increasing concentration of CC. The potentiodynamic polarization results reveal that CC act as a mixed-type inhibitor by retarding both cathodic and anodic corrosion reactions. Additionally, the synergism was carried out between CC and KI to improve the corrosion inhibition behavior of CC on mild steel. The adsorption of both CC alone and the combined inhibitor (CC + KI) on mild steel surface follows Langmuir adsorption isotherm. The synergism parameter (S (theta) ) was calculated to recognize the existence of synergism between CC and iodide ions. Lastly, an adsorption mechanism of CC molecules with iodide ions is discussed.

Surface modification of mild steel by a self-assembled cetyl-trimethyl ammonium bromide (CTAB) monolayer: Evaluation of its corrosion protection property

The surface of mild steel was modified by generating cetyl-trimethyl ammonium bromide (CTAB) self-assembled monolayer (SAM) to enhance the corrosion resistance property. The experimental parameters (pH and time) for SAM generation were optimized. The modified surface was characterized by infrared reflection absorption spectroscopy (IRRAS) and contact angle measurements. The SAM generated in 1 mM solution of CTAB at pH 2.5 for 2 h showed a regimented monolayer. Polarization and electrochemical impedance spectroscopic (EIS) studies demonstrated a significant enhancement in the corrosion resistance property of the SAM protected steel in both 1 M HCl and 3.5% NaCl solution. The CTAB SAM surface substantially reduced the corrosion rate by approximately 4 times in 1 M HCl and 1.5 times in 3.5% NaCl media as compared to bare steel. Scanning electron microscopy images confirmed the formation of lesser amounts of corrosion products on the SAM protected surface. (C) 2015 Elsevier B.V. All rights reserved.

Erosion-corrosion of mild steel in a temperature gradient

Thinning of heat-exchanger tubes by erosion-corrosion has been a problem in fluidized bed combustors (FBCs), particularly at lower metal temperatures where thicker, mechanically protective oxide scales are unable to form. Many laboratory-scale tests have shown a decrease in material loss at higher temperatures, in a similar manner to FBC boilers, but also show a decrease in wastage at low temperatures (e.g. 200°C) which has not been detected in boilers. It has been suggested that this difference is due to laboratory tests being carried out isothermally whereas in a FBC boiler the fluidized bed is considerably hotter than the metal heat exchanger tubing. In this laboratory study the simulation was therefore improved by internally cooling one of the two low carbon steel specimens. These were rotated in a horizontal plane within a lightly fluidized bed with relative particle velocities of 1.3-2.5 m s-1. Tests were carried out over a range of bed temperatures (200-500°C) and cooled specimen surface temperatures (115-500°C), with a maximum temperature difference between the two of 320°C. Although specimens exposed isothermally still showed maximum wastage at intermediate temperatures (about 350°C), those which were cooled showed high levels of wastage at temperatures as low as 200°C in a similar manner to FBC boilers. Cooling may modify the isothermal erosion-corrosion curve, causing it to broaden and the maximum wastage rate to shift to lower temperatures. © 1995.

Stress corrosion studies of ion implanted austenitic steel

Stress corrosion studies of 50 Mn18Cr4 austenitic steel implanted with 120 keV N+, 100 keV Cr+, 200 keV and 400 keV Er+ ions were carried out by constant strain method in the nitrate solution. Surface composition and depth profiles of the implanted material were measured by AES sputter etching technique. The results exhibit that nitrogen implantation has no significant affection to the stress corrosion, but the chromium and erbium implantation has prolonged the incubation period of the stress corrosion cracking. (C) 1999 Kluwer Academic Publishers.

Corrosion inhibition of carbon steel in tetra-n-butylammonium bromide aqueous solution by benzotriazole and Na3PO4

The corrosion inhibition behavior of benzotriazole, Na3PO4 and their mixture on carbon steel in 20 wt.% (0.628 mol l(-1)) tetra-n-butylammonium bromide aerated aqueous solution was investigated by weight-loss test, potentiodynamic polarization measurement, electrochemical impedance spectroscopy and scanning electron microscope/energy dispersive X-ray techniques. The inhibition action of BTA or SP or inhibitors mixture on the corrosion of carbon steel is mainly due to the inhibition of anodic process of corrosion. The results revealed that inhibitors mixtures have shown synergistic effects at lower concentration of inhibitors. At 2 g l(-1) BTA and 2 g l(-1) SP showed optimum enhanced inhibition compared with their individual effects.

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) Omega cm(2), whereas that for pure ER coating fell below 10(6) Omega 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 mu m EB/ER coating protected steel-copper couple for at least 2000 h.

INHIBITION OF CORROSION BY HEXADECYL TRIMETHYL AMMONIUM BROMIDE LANGMUIR-BLODGETT MONOLAYERS ON CARBON-STEEL

Langmuir-Blodgett (LB) monolayers of hexadecyl trimethyl ammonium bromide (HTAB) were deposited onto a carbon steel surface to investigate the inhibition of corrosion by measurement of the polarization resistance and cyclic voltammetry. The corrosion proc

Adsorption and Corrosion Inhibition Behavior of Mild Steel by One Derivative of Benzoic-Triazole in Acidic Solution

A newly synthesized benzoic-triazole derivative 3,5-dimethylbenzoic acid [1,2,4]triazol-l-ylmethyl ester (DBT) was investigated as a corrosion inhibitor of mild steel in 1 M HCl solution using weight loss measurements, potentiodynamic polarization, SEM, and EIS methods. The results revealed that DBT was an excellent inhibitor, and the inhibition efficiencies obtained from weight loss and electrochemical experiments were in good agreement. Using the potentiodynamic polarization technique, the inhibitor was proved to have a mixed-type character for mild steel by suppressing both anodic and cathodic reactions on the metal surface. The number of water molecules (X) replaced by a molecule of organic adsorbate was determined from the Flory-Huggins, Dhar-Flory-Huggins, and Bockris-Swinkels substitutional adsorption isotherms applied to the data obtained from the gravimetric experiments performed on a mild steel specimen in 1 M HCl solution at 298 K.

Boundary Element Method (BEM) Analysis for Galvanic Corrosion of Hot Dip Galvanized Steel Immersed in Seawater

A numerical analysis of galvanic corrosion of hot-dip galvanized steel immersed in seawater was presented. The analysis was based on the boundary element methods (BEMs) coupled with Newton-Raphson iterative technique to treat the nonlinear boundary conditions, which were determined by the experimental polarization curves. Results showed that galvanic current density concentrates on the boundary of steel substrate and zinc coating, and the sacrificial protection of zinc coating to steel substrate results in overprotection of steel cathode. Not only oxygen reduction but also hydrogen reduction could occur as cathode reactions, which probably led up to the adsorption and absorption of hydrogen atoms. Flat galvanized steel tensile sample shows a brittle behavior similar to hydrogen embrittlement according to the SSRT (show strain rate test) in seawater.

Corrosion inhibition of mild steel in acidic solution by some oxo-triazole derivatives

The oxo-triazole derivative (DTP) was synthesized and its inhibiting action on the corrosion of mild steel in sulphuric acid was investigated by means of weight loss, potentiodynamic polarization, EIS and SEM. The results revealed that DTP was an excellent inhibitor and the inhibition efficiencies obtained from weight loss experiment and electrochemical experiment were in good agreement. Potentiodynamic polarization studies clearly revealed that DTP acted essentially as the mixed-type inhibitor. Thermodynamic and kinetic parameters were obtained from weight loss of the different experimental temperatures, which suggested that at different temperatures (298-333 K) the adsorption of DTP on metal surface obeyed Langmuir adsorption isotherm model. (C) 2009 Elsevier Ltd. All rights reserved.