• Corrosion Science and Technology
• /
• v.6 no.2
• /
• pp.68-73
• /
• 2007

The toxicity of chromium that is used to impart corrosion resistance to galvanized steel created environmental and health-related concerns and generated a great deal of interest in developing chrome-free treatment coatings. In the present work, organic-inorganic composite coatings were used to coat electrogalvanized steel (EG) sheets for corrosion protection without degrading its weldability property. The new coatings composed of specially modified polyurethane dispersion hybridized with silicate and unique inorganic-organic inhibitors were developed during this work. It was found that about $1{\mu}m$ thickness of coating layer is secure enough in corrosion resistance of flat and formed part even after alkaline degreasing. Overall chemical resistances including fingerprint resistance and paint adhesion property were satisfied with the test specification of Sony technical standard of SS-00260-2002. Therefore, it is concluded that the newly developed chrome-free product can replace the conventional chromated product.

• Corrosion Science and Technology
• /
• v.5 no.5
• /
• pp.160-167
• /
• 2006

S-Acetyl Isothiourea Acetate (S-AITA) was synthesized in the laboratory and this influence on the inhibition of corrosion of mild steel in 1.11 N hydrochloric and 1.12 N sulphuric acids was investigated by weight loss and potentiostatic polarization techniques at 303K, 353K and 403K. These results were confirmed by the impedance technique. The inhibition efficiency increased with increase in concentration of inhibitor and decreased with rise in temperature from 303K to 403K. The maximum inhibition efficiency of S-AITA was found to be 99.95% (0.5% of S-AITA) at 303K in sulphuric acid. The adsorption of this compound on the mild steel surface from the acids has been found to obey Temkin's adsorption isotherm. The potentiostatic polarization results revealed that S-AITA was a mixed type inhibitor. Some thermodynamic parameters i.e., activation energy (Ea), free energy of adsorption (${\Delta}G_{ads}$), enthalpy of adsorption (${\Delta}H$) and entropy of adsorption (${\Delta}S$) were also calculated from weight loss data.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.11a
• /
• pp.65-66
• /
• 2021

In this study, the optimum amount of hybrid inhibitors i.e. L-Arginine (LA) and sodium phosphate tribasic dodecahydrate (SP), applied for carbon steel rebar in simulated pore concrete (SCP) solution contaminated with 3.5 wt.% NaCl, was discovered. The corrosion inhibition performance of hybrid inhibitors was investigated by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization. The highest corrosion inhibition efficiency was found as 99.52% corresponding to 2% LA and 0.25% SP after 210 h exposure. Anodic type inhibition action was confirmed by potentiodynamic polarization study. Surface studies including scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to figure out the surface morphology of the steel rebar treated with hybrid inhibitors in order to collaborate with electrochemical studies.

• Magazine of the Korea Concrete Institute
• /
• v.10 no.6
• /
• pp.325-333
• /
• 1998

Under the seawater environment, the reinforced concrete structure is deteriorated due to physical and chemical attacks. The main deterioration mechanism is the chloride corrosion of reinforcing steel. The corrosion inhibitors have been used to protect the rebars from corrosion which are susceptible to chlorides in concrete. However, there is not clear conclusion about corrosion inhibitors yet. In this study, it is made the accelerated experiment with 3 kinds of corrosion inhibitors for various chloride ingresses. It is estimated corrosion inhibitors that inhibitors by Half-Cell Potential, corrosion area ratio and weight loss ratio. It is concluded that inhibitors are not effective to corrosion inhibition for excessive chloride ingress. However, the effect of inhibition is directly proportional ot contents of corrosion inhibitors in some chloride ingress.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.10a
• /
• pp.63-67
• /
• 2002

The induced chemical and salt solution in water or admixture are originated to the corrosion process of the steeo rebar. These liquids penetrate into concrete as the accompanied by the chemical reaction and cause to attack the steel rebar in concrete. Concrete surfaces which it exposed to deicing, water and sea water is allowed to enter the chlorides in the structures. To prevent from the source of corrosion and deterioration Is subjected to put an end to corrode or reduce to contaminate on the steel rebar. As this reason the MCI 2022 products are applied to the surface of concrete and steel rebar. The concrete samples were made of to the kind of four, i.e. RF, MR, MS, and MM. Corrosion inhibitor is applied to coat on the surface of concrete after it had been cured for 28days. Specimen were immersed in a 3.5％ sodium chloride solution. Concrete specimen were tested to determine the changes of the resistance polarization, Rp, over a 22 weeks period. MCI 2022 is significantly shown the corrosion inhibition of steel rebar in 3.5% NaCl solution. In the each different concrete sample, MS and MM is seemed to be better than others. The results are proofed that MCI 2022 is promised to maintain the inhibition of corrosion with high resistance polarization of the steel rebar in concrete.

• Corrosion Science and Technology
• /
• v.21 no.2
• /
• pp.77-88
• /
• 2022

Schiff base quinazoline derivative viz., 3-((2-hydroxy-3-methoxybenzylidene)amino)-2-methylquinazolin-4(3H)-one (SB-Q), was synthesized in this study. Its corrosion protection impact on mild steel (MS) in 1 M hydrochloric acid solution was examined by performing weight loss measurements. The protective efficacy of SB-Q on MS in 1 M HCl was investigated based on its concentrations, immersion period, and immersion temperature. SB-Q was found to be an efficient inhibitor for the corrosion of MS. Its inhibition efficiency was improved by increasing the concentration of SB-Q to an optimal concentration of 500 ppm. Its inhibition efficacy was 96.3% at 303K. Experimental findings revealed that its inhibition efficiency was increased with increasing immersion time, but decreased with an increase in temperature. The adsorption of SB-Q molecules was followed the Langmuir adsorption isotherm model. The adsorption of the examined inhibitor molecules on the surface of mild steel was studied by density functional theory (DFT). DFT investigation confirmed weight loss findings.

• Journal of the Korean Chemical Society
• /
• v.56 no.4
• /
• pp.401-405
• /
• 2012

Corrosion inhibition efficiencies of holy basil on Al in HCl solution were studied by weight loss and thermometric methods in presence and in absence of stem extract of three different varieties of holy basil viz. ocimum basilicum ($E_B$), ocimum canum ($E_C$) and ocimum sanctum ($E_S$). Inhibition efficiency increases with the increasing concentration of stem extract and decreases with increases in acid strength. Results show that all varieties under study are good corrosion inhibitors, among which, $E_B$ is most effective. Maximum inhibition efficiency was found 97.09% in 0.5N HCl solution with 0.6% stem extract. The Langmuir adsorption isotherm indicates that surface coverage also increases with increasing in the concentration of extract of stem in HCl solution.

• Journal of the Korean Chemical Society
• /
• v.54 no.6
• /
• pp.680-686
• /
• 2010

Inhibition effects of alanine(Ala), asparagine(Asn), aspartic acid(Asp), glutamine(Gln) and methionine(Met) on the corrosion of copper were investigated in aerated artificial sea water. Amino acid adsorption process in copper surface can be explained by Temkin logarithmic isotherm due to the interaction between the adsorbed molecules. The inhibition efficiency for the copper corrosion depended on the concentration of amino acids.

• Corrosion Science and Technology
• /
• v.22 no.3
• /
• pp.137-152
• /
• 2023

Polarization behavior and corrosion inhibition of copper in acidic chloride solutions containing benzotriazole were studied. Pourbaix diagrams constructed for copper in NaCl solutions with different BTAH concentrations were used to understand the polarization behavior. Open circuit potential (OCP) depended not only on chloride concentration, but also on whether a CuBTA layer was formed on the copper surface. Only when the (pH, OCP) was located well in the CuBTA region of the Pourbaix diagram, a stable corrosion inhibiting CuBTA layer was formed, which was confirmed by X-ray Photoelectron Spectroscopy (XPS) and a long-term corrosion test. The OCP for the CuBTA layer decreased logarithmically with increasing [Cl^-] activity in the solution. A minimum BTAH concentration required to form a CuBTA layer for a given NaCl concentration and pH were determined from the Pourbaix diagram. It was found that 320 ppm BTAH solution could be used to form a corrosion-inhibiting CuBTA layer inside the corrosion pit in the sprinkler copper tube, successfully reducing water leakage rate of copper tubes. These experimental results could be used to estimate water chemistry inside a corrosion pit.

• Corrosion Science and Technology
• /
• v.4 no.6
• /
• pp.231-235
• /
• 2005

The inhibitive effect of extracts of tamarind seeds and jackfruit seeds, curry leaves and henna leaves on corrosion of mild steel in 1M HCl solution have been studied by weight loss, potentiodynamic polarization and impedance measurements. Results obtained from the electrochemical techniques were in good agreement with weight loss results. From the weight loss data, the values of surface coverage ($\Theta$) and corrosion rate were calculated. The inhibition efficiency (IE) increased with increasing inhibitor concentration in 1M HCl solution. In all the cases the adsorption of the natural product extracts on the mild steel surface from 1M HCl follows the Langmuir adsorption isotherm relationship. Potentiodynamic polarization studies reveal the fact that all the four natural product extracts act as mixed type inhibitors. The decrease in the inhibition efficiency follows the order: Extracts of jackfruit seed>henna leaves>curry leaves>tamarind seed.