International Journal of Corrosion The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Evaluation of Corrosion Inhibition of Mild Steel in 1 M Hydrochloric Acid Solution by Mollugo cerviana Mon, 21 Jul 2014 08:33:18 +0000 The inhibiting effect of methanolic extract of Mollugo cerviana plant on the corrosion of mild steel in 1 M HCl solution has been investigated by different techniques like potentiodynamic polarization, electrochemical impedance spectroscopy, and weight loss methods for five different concentrations of plant extract ranging from 25 to 1000 mg/L. The results indicated that the corrosion inhibition efficiency increased on increasing plant extract concentration till 500 mg/L and decreased on further increasing concentration. The extract was a mixed type inhibitor with the optimum inhibition concentration of 500 mg/L in potentiodynamic polarization. The adsorption of the plant extract on the mild steel surface was found to obey Langmuir adsorption isotherm. Surface analysis was also carried out to find out the surface morphology of the mild steel in the presence and in the absence of the inhibitor to find out its efficiency. The obtained results showed that the Mollugo cerviana extract acts as a good inhibitor for the corrosion of mild steel in 1 M HCl solution. P. Arockiasamy, X. Queen Rosary Sheela, G. Thenmozhi, M. Franco, J. Wilson Sahayaraj, and R. Jaya Santhi Copyright © 2014 P. Arockiasamy et al. All rights reserved. Corrosion Behavior of A356-10 Vol.% SiC Composites Cast by Gravity and Squeeze Casting in H2SO4 Solutions Tue, 08 Jul 2014 00:00:00 +0000 Corrosion behavior of A356-10 vol.% SiC composites cast by gravity and squeeze casting is evaluated. For this purpose, prepared samples were immersed in H2SO4 solution for 2 hrs. at open circuit potential. Tafel polarization and electrochemical impedance spectroscopy (EIS) were carried out to study the corrosion resistance of composites. The results showed that corrosion resistance of composites cast by squeeze casting is higher than that of the gravity cast composites. The micrographs of scanning electron microscope (SEM) clearly showed the squeeze casting composites exhibit a good dispersion/matrix interface when compared with composites produced by gravity casting. A. Fattah-alhosseini, M. Ranjbaran, and S. Vajdi Vahid Copyright © 2014 A. Fattah-alhosseini et al. All rights reserved. Effect of Cold-Rolled Thickness Reduction Degree on Characteristics of Hydrogen Diffusion in Silicon Steel Tue, 17 Jun 2014 08:17:38 +0000 The characteristic of hydrogen uptake and diffusion in the cold-rolled silicon steel was investigated by electrochemical hydrogen permeation technique performed under different cathodic charging current density and cold-rolled thickness reduction degree. The results indicated that anodic permeation current density increased with increasing cathodic charging current for the specimens. Moreover, the anodic steady state permeation current density and the solubility increased with an increase in the cold-rolled thickness reduction degrees. The breakthrough time of hydrogen in the specimens was shortened with increasing thickness reduction degrees, and the value of the hydrogen diffusivity decreased gradually with increasing thickness reduction degrees. Yongfeng Li, Lian Cai, Guanjun Liu, and Lijie Ma Copyright © 2014 Yongfeng Li et al. All rights reserved. Characterization of Corrosion Products on Carbon Steel Exposed to Natural Weathering and to Accelerated Corrosion Tests Sun, 15 Jun 2014 05:09:10 +0000 The aim of this work was to compare the corrosion products formed on carbon steel plates submitted to atmospheric corrosion in urban and industrial atmospheres with those formed after accelerated corrosion tests. The corrosion products were characterized by X-ray diffraction, Mössbauer spectroscopy, and Raman spectroscopy. The specimens were exposed to natural weathering in both atmospheres for nine months. The morphologies of the corrosion products were evaluated using scanning electron microscopy. The main product found was lepidocrocite. Goethite and magnetite were also found on the corroded specimens but in lower concentrations. The results showed that the accelerated test based on the ASTM B117 procedure presented poor correlation with the atmospheric corrosion tests whereas an alternated fog/dry cycle combined with UV radiation exposure provided better correlation. Renato Altobelli Antunes, Rodrigo Uchida Ichikawa, Luis Gallego Martinez, and Isolda Costa Copyright © 2014 Renato Altobelli Antunes et al. All rights reserved. Corrosion Problems in Incinerators and Biomass-Fuel-Fired Boilers Mon, 12 May 2014 06:15:28 +0000 Incinerators are widely used to burn the municipal waste, biowaste, wood, straw, and biomedical waste. Combustion of these types of waste results in generation of chlorides of sodium and potassium which may attack the metallic part of the incinerator. In biofuel-fired boilers, similar type of highly corrosive environment is present. Attempt has been made to review the corrosion problems and their solutions as per the available literature. Deepa Mudgal, Surendra Singh, and Satya Prakash Copyright © 2014 Deepa Mudgal et al. All rights reserved. Hot Corrosion Behaviour of Detonation Gun Sprayed Stellite-6 and Stellite-21 Coating on Boiler Steel SAE 431 at 900°C Tue, 06 May 2014 07:35:13 +0000 Hot corrosion is the serious problem in gas turbines, superheaters, and economizers of coal-fired boilers. It occurs due to the usage of wide range of fuels such as coal, oil, and so on at the elevated temperatures. Protective coatings on boiler steels are used under such environments. In the present investigation, Stellite-6 and Stellite-21 coatings have been deposited on boiler steel SAE 431 by detonation gun method. The hot corrosion performance of Stellite-6 and Stellite-21 coated as well as uncoated SAE 431 steel has been evaluated in aggressive environment of Na2SO4-82%Fe2(SO4)3 under cyclic conditions at an elevated temperature of 900°C for total duration of 50 cycles. Thermogravimetric technique was used to approximate the kinetics of hot corrosion. Stellite-6 coating imparted better hot corrosion resistance than Stellite-21 coating in the given environment. Scanning electron microscopy was used to characterize the surface of hot corrosion products. N. K. Mishra, A. K. Rai, S. B. Mishra, and R. Kumar Copyright © 2014 N. K. Mishra et al. All rights reserved. Assessment of Automotive Coatings Used on Different Metallic Substrates Tue, 29 Apr 2014 08:54:14 +0000 Four epoxy primers commonly used in the automotive industry were applied by gravity pneumatic spray gun over metallic substrates, specifically, steel, electrogalvanized steel, hot-dip galvanized steel, and aluminum. A two-component polyurethane resin was used as topcoat. To evaluate the performance of the different coating systems, the treated panels were submitted to mechanical testing using Persoz hardness, impact resistance, cupping, lattice method, and bending. Tribological properties of different coating systems were conducted using pin on disc machine. Immersion tests were carried out in 5% NaCl and immersion tests in 3% NaOH solutions. Results showed which of the coating systems is more suitable for each substrate in terms of mechanical, tribological, and anticorrosive performance. W. Bensalah, N. Loukil, M. De-Petris Wery, and H. F. Ayedi Copyright © 2014 W. Bensalah et al. All rights reserved. Corrosion of Steel in High-Strength Self-Compacting Concrete Exposed to Saline Environment Wed, 23 Apr 2014 14:29:26 +0000 A research work was carried out to investigate the effectiveness of high-strength self-compacting concrete (SF-R) in controlling corrosion of embedded steel. Reinforced concrete cylinders and plain cubes were subjected to 5% NaCl solution. Slump flow, J-ring, V-funnel, compressive strength, electrical resistance, and electrochemical tests were conducted. Corrosion resisting characteristics of steel were examined by monitoring corrosion potential, polarization resistance, corrosion currents, and Tafel plots. The relationship between corrosion current density and corrosion potential was established. Results were compared with characteristics of a grade 40 MPa reference concrete (R) and grade 70 MPa conventional self-compacting concrete (SP). Results indicated that at 270 days of exposure, the corrosion currents for steel in SF-R were 63- and 16-fold lower compared to those of steel in R and SP concretes, respectively. This concrete showed a considerable increase in electrical resistance and compressive strength of 96 MPa at 28 days of exposure. Relying on corrosion risk classification based on corrosion current densities and corrosion potentials, the steel in SF-R concrete is definitely in the passive condition. The splendid durability performance of steel in SF-R concrete linked to adorable self-compacting features could furnish numerous opportunities for future structural applications in severe environmental conditions. Hana A. Yousif, Farqad F. Al-Hadeethi, Bashar Al-Nabilsy, and Amani N. Abdelhadi Copyright © 2014 Hana A. Yousif et al. All rights reserved. Laboratory Assessment of Select Methods of Corrosion Control and Repair in Reinforced Concrete Bridges Thu, 10 Apr 2014 12:37:28 +0000 Fourteen reinforced concrete laboratory test specimens were used to evaluate a number of corrosion control (CoC) procedures to prolong the life of patch repairs in corrosion-damaged reinforced concrete. These specimens included layered mixed-in chlorides to represent chloride contamination due to deicing salts. All specimens were exposed to accelerated corrosion testing for three months, subjected to patch repairs with various treatments, and further subjected to additional three months of exposure to accelerated corrosion. The use of thermal sprayed zinc, galvanic embedded anodes, epoxy/polyurethane coating, acrylic coating, and an epoxy patch repair material was evaluated individually or in combination. The specimens were assessed with respect to corrosion currents (estimated mass loss), chloride ingress, surface rust staining, and corrosion of the reinforcing steel observed after dissection. Results indicated that when used in patch repair applications, the embedded galvanic anode with top surface coating, galvanic thermal sprayed zinc, and galvanic thermal sprayed zinc with surface coating were more effective in controlling corrosion than the other treatments tested. Matthew D. Pritzl, Habib Tabatabai, and Al Ghorbanpoor Copyright © 2014 Matthew D. Pritzl et al. All rights reserved. Simulation of the Relaxation Potential Profile of an ac-dc-ac Test Thu, 03 Apr 2014 06:42:45 +0000 The relaxation period of the accelerated ac-dc-ac test for coatings is associated with the transient electrochemistry that occurs when the immersed coated system is allowed to return to a stable open-circuit condition after being subjected to a cathodic potential. A mathematical model of the transient electrochemistry that occurs during this relaxation period is presented for coated aluminum. Expressions for the corrosion potential and corrosion current as functions of the local pH at the metal-coating interface were developed using reported experimental results. These expressions enabled the simulation of the transient electrochemistry under the constraint of balanced anodic and cathodic current densities. Regression of the transient relaxation potential profiles to exponential decay functions provided time-constant characterization of the profiles. Simulated results are presented that demonstrate the influences of the coating's porosity and thickness, the applied dc potential and the metal-coating interface condition on the time-constants associated with the relaxation profile. Interpretation of experimentally reported relaxation potential profiles supported the analysis of the simulated results. Kerry N. Allahar, Michael F. Hurley, Erik D. Sapper, and Darryl P. Butt Copyright © 2014 Kerry N. Allahar et al. All rights reserved. Parameter Studies on High-Velocity Oxy-Fuel Spraying of CoNiCrAlY Coatings Used in the Aeronautical Industry Thu, 06 Mar 2014 10:57:48 +0000 The thermal spraying process is a surface treatment which does not adversely affect the base metal on which it is performed. The coatings obtained by HVOF thermal spray are employed in aeronautics, aerospace, and power generation industries. Alloys and coatings designed to resist oxidizing environments at high temperatures should be able to develop a surface oxide layer, which is thermodynamically stable, slowly growing, and adherent. MCrAlY type (M = Co, Ni or combination of both) coatings are used in wear and corrosion applications but also provide protection against high temperature oxidation and corrosion attack in molten salts. In this investigation, CoNiCrAlY coatings were produced employing a HVOF DJH 2700 gun. The work presented here focuses on the influences of process parameters of a gas-drive HVOF system on the microstructure, adherence, wear, and oxygen content of CoNiCrAlY. The results showed that spray distance significantly affects the properties of CoNiCrAlY coatings. J. A. Cabral-Miramontes, C. Gaona-Tiburcio, F. Almeraya-Calderón, F. H. Estupiñan-Lopez, G. K. Pedraza-Basulto, and C. A. Poblano-Salas Copyright © 2014 J. A. Cabral-Miramontes et al. All rights reserved. Effect of C/Si Ratio on the Electrochemical Behavior of a-SiCx:H Coatings on SS301 Substrate Deposited by PECVD Wed, 05 Mar 2014 15:27:44 +0000 Amorphous hydrogenated silicon carbide (a-SiCx:H) coatings were deposited on stainless steel 301 (SS301) using plasma enhanced chemical vapor deposition with the methane gas flow ranging from 30 to 90 sccm. XRD spectra confirmed the amorphous structure of these coatings. The as-deposited coatings all exhibited homogenous dense feature, and no porosities were observed in SEM and AFM analysis. The a-SiCx:H coatings remarkably increased the corrosion resistance of the SS301 substrate. With the increase of the C concentration, the a-SiCx:H coatings exhibited significantly enhanced electrochemical behavior. The a-SiCx:H coating with the highest carbon concentration acted as an excellent barrier to charge transfer, with a corrosion current of  A/cm2 and a breakdown voltage of 1.36 V, compared to  A/cm2 and 0.34 V for the SS301 substrate. D. Li, S. Guruvenket, J. A. Szpunar, and J. E. Klemberg-Sapieha Copyright © 2014 D. Li et al. All rights reserved. Protection of Steel Corrosion in Concrete Members by the Combination of Galvanic Anode and Nitrite Penetration Wed, 12 Feb 2014 09:39:32 +0000 Chloride induced-corrosion of steel bars in concrete can make cracks and exfoliation in near-surface regions in reinforced concrete structures. In this paper, we described the basic concept and practice of steel bars corrosion protection method by the combination of galvanic anode (zinc wire) and the penetration of nitrite ions from mortar layers containing a large amount of lithium nitrite. Minobu Aoyama, Shinichi Miyazato, and Mitsunori Kawamura Copyright © 2014 Minobu Aoyama et al. All rights reserved. Boric Acid as an Accelerator of Cerium Surface Treatment on Aluminum Thu, 16 Jan 2014 07:26:37 +0000 Aluminum pieces are often used in various industrial processes like automotive and aerospace manufacturing, as well as in ornamental applications, so it is necessary to develop processes to protect these materials, processes that can be industrialized to protect the aluminum as well or better than chromate treatments. The purpose of this research is to evaluate boric acid as an accelerator by optimizing its concentration in cerium conversion coatings (CeCC) with 10-minute immersion time with a concentration of 0.1 g L−1 over aluminum to protect it. The evaluation will be carried out by measuring anticorrosion properties with electrochemical techniques (polarization resistance, , polarization curves, PC, and electrochemical impedance spectroscopy, EIS) in NaCl 3.5% wt. aqueous solution and surface characterization with scanning electron microscopy (SEM). K. Cruz-Hernández, S. López-Leon, and F. J. Rodríguez-Gómez Copyright © 2014 K. Cruz-Hernández et al. All rights reserved. Approaches for Modelling the Residual Service Life of Marine Concrete Structures Sun, 12 Jan 2014 16:57:10 +0000 This paper deals with the service life design of existing reinforced concrete structures in a marine environment. The general procedure of condition assessment for estimating the residual service life of structures before a repair measure is illustrated. For assessment of the residual service life of structures which have undergone a repair measure a simplified mathematical model of chloride diffusion in a 2-layer system is presented. Preliminary probabilistic calculations demonstrate the effect of various conditions on the residual service life. First studies of the chloride diffusion in a 2-layer system have been conducted using the finite element method. Results of a long-term exposure test are presented to illustrate the performance of two different repair materials. The distribution of residual chlorides after application of a repair material is being studied in laboratory investigations. The residual chlorides migrate from the concrete layer into the new layer immediately after the repair material has been applied to the concrete member. The content and gradient of residual chlorides, along with the thickness and the chloride ingress resistance of both the remaining and the new layer of cover, will determine the residual service life of the repaired structures. Amir Rahimi, Christoph Gehlen, Thorsten Reschke, and Andreas Westendarp Copyright © 2014 Amir Rahimi et al. All rights reserved. Theoretical Study of Chloro-N-(4-methoxybenzylidene)aniline Derivatives as Corrosion Inhibitors for Zinc in Hydrochloric Acid Thu, 26 Dec 2013 10:54:56 +0000 The density functional theory (DFT) was used to investigate the corrosion inhibition of three inhibitors on zinc. Quantum chemical parameters such as the energy of highest occupied molecular orbital (), the energy of lowest unoccupied molecular orbital (), energy gap , hardness , softness , electrophilicity index , the fraction of electrons transferred from inhibitor molecule to the metal surface, energy change when both processes occur, namely, charge transfer to the molecule and backdonation from the molecule (), natural charge , and Fukui functions have been calculated by using B3LYP/6-31+G(d) basis set. The relation between the inhibition efficiency and quantum chemical parameters has been discussed in order to elucidate the inhibition mechanism of the chloro-N-(4-methoxybenzylidene)aniline derivatives. S. Kumar, D. G. Ladha, P. C. Jha, and N. K. Shah Copyright © 2013 S. Kumar et al. All rights reserved. Garcinia indica as an Environmentally Safe Corrosion Inhibitor for Aluminium in 0.5 M Phosphoric Acid Thu, 19 Dec 2013 14:49:04 +0000 The Inhibitive and adsorption properties of aqueous extract of seeds of Garcinia indica extract (GIE) have been studied for corrosion control of aluminium in 0.5 M phosphoric acid solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques at to . The effects of inhibitor concentration on the inhibition action were investigated. Polarization measurements showed that the GIE acted as mixed inhibitor and the inhibitor molecules followed chemical adsorption on the surface of aluminium. The adsorption of GIE on metal surface obeyed Langmuir adsorption isotherm. The surface morphology of aluminium, in the absence and in the presence of GIE in 0.5 M phosphoric acid solution, was studied using scanning electron microscopy (SEM). Results obtained from both of the electrochemical techniques were in good agreement with each other. Deepa Prabhu and Padmalatha Rao Copyright © 2013 Deepa Prabhu and Padmalatha Rao. All rights reserved. Electrochemical and Oxidation Behavior of Yttria Stabilized Zirconia Coating on Zircaloy-4 Synthesized via Sol-Gel Process Tue, 17 Dec 2013 18:31:41 +0000 Sol-gel 8 wt.% Yttria Stabilized Zirconia (YSZ) thin films were prepared on zirconium (zircaloy-4 alloy) by dip-coating technique followed by heat treating at various temperatures (200°C, 400°C, and 700°C) in order to improve both electrochemical corrosion and high temperature oxidation properties of the substrate. Differential thermal analysis and thermogravimetric analysis (DTA-TG) revealed the coating formation process. X-ray diffraction (XRD) was used to determine the crystalline phase structure transformation. The morphological characterization of the coatings was carried out using scanning electron microscopy (SEM). The electrochemical behavior of the coated and uncoated samples was investigated by means of open circuit potential, Tafel, and electrochemical impedance spectroscopy (EIS) in a 3.5 wt.% NaCl solution. The homogeneity and surface appearance of coatings produced was affected by the heat treatment temperature. According to the corrosion parameters, the YSZ coatings showed a considerable increase in the corrosion resistance, especially at higher heat treatment temperatures. The coating with the best quality, from the surface and corrosion point of view, was subjected to oxidation test in air at 800°C. The coated sample presented a 25% reduction in oxidation rate in comparison with bare substrate. S. Rezaee, Gh. R. Rashed, and M. A. Golozar Copyright © 2013 S. Rezaee et al. All rights reserved. The Corrosion Performance of Galvanized Steel in Closed Rusty Seawater Tue, 17 Dec 2013 18:23:40 +0000 The corrosion performance of galvanized steel in closed rusty seawater (CRS) was investigated using weight loss, Tafel polarization curve, and electrochemical impedance spectroscopy. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were carried out for morphological and chemical characterization of the rust layer absorbed on the zinc coating. Effects of temperature and hydrostatic pressure on corrosion resistance of galvanized steel were studied. Results indicated that rust layer could induce pitting corrosion on the zinc coating under the Cl− erosion; high temperature accelerated the corrosion rate of zinc coating and inhibited the absorption of rust layer; the polarization resistance () of galvanized steel increased with the increase of hydrostatic pressure in CRS. Shuan Liu, Huyuan Sun, Ning Zhang, and Lijuan Sun Copyright © 2013 Shuan Liu et al. All rights reserved. Effect of Nitrite Ions on Steel Corrosion Induced by Chloride or Sulfate Ions Tue, 17 Dec 2013 14:14:19 +0000 The influence of nitrite concentration on the corrosion of steel immersed in three simulated pH environments containing chloride ions or sulfate ions has been investigated by comparing and analyzing the change of half-cell potential, the change of threshold level of or , the change of threshold level of / or / mole ratio, and the changes of anodic/cathodic polarization curves and Stern-Geary constant . The corrosivity of chloride ions against sulfate ions also has been discussed in pH 12.6, pH 10.3, and pH 8.1 environments containing 0, 0.053, and 0.2 mol/L , respectively. Zhonglu Cao, Makoto Hibino, and Hiroki Goda Copyright © 2013 Zhonglu Cao et al. All rights reserved. Statistics Analysis Measures Painting of Cooling Tower Mon, 16 Dec 2013 09:41:59 +0000 This study refers to the cooling tower of Megalopolis (construction 1975) and protection from corrosive environment. The maintenance of the cooling tower took place in 2008. The cooling tower was badly damaged from corrosion of reinforcement. The parabolic cooling towers (factory of electrical power) are a typical example of construction, which has a special aggressive environment. The protection of cooling towers is usually achieved through organic coatings. Because of the different environmental impacts on the internal and external side of the cooling tower, a different system of paint application is required. The present study refers to the damages caused by corrosion process. The corrosive environments, the application of this painting, the quality control process, the measures and statistics analysis, and the results were discussed in this study. In the process of quality control the following measurements were taken into consideration: (1) examination of the adhesion with the cross-cut test, (2) examination of the film thickness, and (3) controlling of the pull-off resistance for concrete substrates and paintings. Finally, this study refers to the correlations of measurements, analysis of failures in relation to the quality of repair, and rehabilitation of the cooling tower. Also this study made a first attempt to apply the specific corrosion inhibitors in such a large structure. A. Zacharopoulou, E. Zacharopoulou, and G. Batis Copyright © 2013 A. Zacharopoulou et al. All rights reserved. Combating Corrosion Degradation of Turbine Materials Using HVOF Sprayed 25% (Cr3C2-25(Ni20Cr)) + NiCrAlY Coating Sat, 07 Dec 2013 11:09:07 +0000 High velocity oxy fuel process (HVOF) is an advanced coating process for thermal spraying of coatings on to components used in turbines. HVOF process is a thermal spray coating method and is widely used to apply wear, erosion, and corrosion protective coatings to the components used in industrial turbines. 25% (Cr3C2-25(Ni20Cr)) + NiCrAlY based coatings have been sprayed on to three turbine materials, namely, Ti-31, Superco-605, and MDN-121. Coated and uncoated substrates were subjected to hot corrosion study under cyclic conditions. Each cycle consisted of 1 hour heating at 800°C followed by 20 minutes air cooling. Gravimetric measurements were done after each cycle and a plot of weight gain as a function of number of cycles is drawn. Parabolic rate constants were estimated for the understanding of corrosion behaviour. It was observed that coated Ti-31 and MDN-121 were more resistant compared to the uncoated ones. Uncoated superco-605 was undergoing sputtering during corrosion study and hence comparison between coated and uncoated superco-605 was difficult. The cross-sectional analysis of the corroded, coated samples indicated the presence of a thin layer of chromium oxide scale on the top of the coating and it imparted better corrosion resistance. Parabolic rate constants also indicated that coating is more beneficial to Ti-31 than to MDN-121. N. Jegadeeswaran, M. R. Ramesh, and K. Udaya Bhat Copyright © 2013 N. Jegadeeswaran et al. All rights reserved. Corrosion Response of Ti6Al4V and Ti15Mo Dental Implant Alloys in the Presence of Listerine Oral Rinse Thu, 05 Dec 2013 11:30:47 +0000 The influence of a commonly used antibacterial mouth rinse, Listerine, on the corrosion behavior of one of the commonly used titanium alloys Ti6Al4V (two-phase structure, i.e., α and β) and a newer Ti15Mo (single β phase) in normal saline solution has been investigated using electrochemical techniques. Interfacial electrochemical changes occurring at the oxide-solution interface have been analysed using EIS circuit modeling. Listerine acts as a corrosion inhibitor for Ti15Mo alloy and a corrosion promoter for Ti6Al4V alloy. Rahul Bhola, Charu Chandra, Faisal M. Alabbas, Sukumar Kundu, Brajendra Mishra, and David L. Olson Copyright © 2013 Rahul Bhola et al. All rights reserved. Corrosion Measurements in Reinforced Fly Ash Concrete Containing Steel Fibres Using Strain Gauge Technique Mon, 25 Nov 2013 18:37:47 +0000 Corrosion of steel bars in concrete is a serious problem leading to phenomenal volume expansion and thereby leading to cover concrete spalling. It is well known that the reinforced concrete structures subjected to chloride attack during its service life cause these detrimental effects. The early detection of this damage potential can extend the service life of concrete. This study reports the comprehensive experimental studies conducted on the identification of corrosion mechanism in different types of reinforced concrete containing class-F fly ash and hooked steel fibres. Fly ash replaced concrete mixes were prepared with 25% and 50% fly ash containing steel fibres at 0.5%, 1.0%, and 1.5% by volume fraction. Corrosion process was investigated in an embedded steel bar (8 mm diameter) reinforced in concrete by passing an impressed current in sodium chloride solution. Strain gauge attached to the rebars was monitored for electrical measurements using strain conditioner. Strain gauge readings observed during the corrosion process exhibited the volume changes of the reinforcement embedded inside the concrete. The corrosion potential of different steel fibre reinforced concrete mixes with fly ash addition showed higher resistance towards the corrosion initiation. V. M. Sounthararajan and A. Sivakumar Copyright © 2013 V. M. Sounthararajan and A. Sivakumar. All rights reserved. Inhibition Behaviour of Some Isonicotinic Acid Hydrazides on the Corrosion of Mild Steel in Hydrochloric Acid Solution Mon, 18 Nov 2013 15:38:12 +0000 New corrosion inhibitors, namely, isonicotinic acid (1H-indol-3-yl-methylene)hydrazide (INIMH) and isonicotinic acid (1H-pyrrol-2-yl-methylene)hydrazide (INPMH), have been synthesized, and their inhibitive characteristics for the corrosion of mild steel in 0.5 M HCl were investigated by mass loss and electrochemical techniques. The structures of the synthesized compounds were confirmed using spectral studies. Potentiodynamic polarization studies revealed that the investigated inhibitors are of mixed type. Various thermodynamic parameters were evaluated. Langmuir adsorption isotherm was found to be the best description for both inhibitors. FTIR spectra, energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) were performed to characterize the passive film on the metal surface. M. P. Chakravarthy and K. N. Mohana Copyright © 2013 M. P. Chakravarthy and K. N. Mohana. All rights reserved. A Revisit to the Corrosion Inhibition of Aluminum in Aqueous Alkaline Solutions by Water-Soluble Alginates and Pectates as Anionic Polyelectrolyte Inhibitors Sun, 17 Nov 2013 13:59:46 +0000 The corrosion behavior of aluminum (Al) in alkaline media in presence of some natural polymer inhibitors has been reinvestigated. The inhibition action of the tested inhibitors was found to obey both Langmuir and Freundlich isotherms models. The inhibition efficiency was found to increase with increasing the inhibitors concentration and decrease with increasing the temperature, suggesting physical adsorption mechanism. Factors such as the concentration and geometrical structure of the inhibitor, concentration of the corrosive medium, and temperature affecting the corrosion rates were examined. The kinetic parameters were evaluated, and a suitable corrosion mechanism consistent with the kinetic results obtained is suggested and discussed. Refat Hassan, Ishaq Zaafarany, Adil Gobouri, and Hideo Takagi Copyright © 2013 Refat Hassan et al. All rights reserved. Anodic Dissolution of Spheroidal Graphite Cast Iron with Different Pearlite Areas in Sulfuric Acid Solutions Sun, 10 Nov 2013 09:11:18 +0000 The rate equation of anodic dissolution reaction of spheroidal graphite cast iron in sulfuric acid solutions at 298 K has been studied. The cast irons have different areas of pearlite. The anodic Tafel slope of 0.043 V decade−1 and the reaction order with respect to the hydroxyl ion activity of 1 are obtained by the linear potential sweep technique. The anodic current density does not depend on the area of pearlite. There is no difference in the anodic dissolution reaction mechanisms between pure iron and spheroidal graphite cast iron. The anodic current density of the cast iron is higher than that of the pure iron. Yoshikazu Miyata, Yuki Kuwahara, Shukuji Asakura, Tadashi Shinohara, Takao Yakou, and Keiichi Shiimoto Copyright © 2013 Yoshikazu Miyata et al. All rights reserved. Marjoram Extract as Corrosion Inhibitor for Dissolution of Zinc in 1.0 M HCl Wed, 23 Oct 2013 15:08:36 +0000 In this study, water marjoram (Origanum marjorana L.) extract was evaluated as corrosion inhibitor for zinc in 1.0 M HCl solution. The polarization measurements showed that this inhibitor is acting as mixed inhibitors for both anodic and cathodic reactions. The results showed that the inhibition efficiency was increased by increasing the inhibitor doses and reached the maximum at 500 ppm. The adsorption of marjoram extract on zinc surface was found to obey Langmuir type isotherm. The efficiency obtained from the impedance measurements was in good agreement with those obtained from the gravimetrical, thermometric, and polarization techniques which prove the validity of these tolls in the measurements of the tested inhibitor. M. Sobhi Copyright © 2013 M. Sobhi. All rights reserved. Corrosion and Inhibition Effects of Mild Steel in Hydrochloric Acid Solutions Containing Organophosphonic Acid Mon, 23 Sep 2013 13:52:39 +0000 A study has been made on the mechanism of corrosion of mild steel and the effect of nitrilo trimethylene phosphonic (NTMP) acid as a corrosion inhibitor in acidic medium, that is, 10% HC1 using the weight loss method and electrochemical techniques, that is, potentiodynamic and galvanostatic polarization measurements. Although corrosion is a long-time process, but it takes place at a faster rate in the beginning which goes on decreasing with due course of time. The above-mentioned methods of corrosion rate determination furnish an average value for a long-time interval. Looking at the versatility and minimum detection limit of the voltammetric method, the authors have developed a new voltammetric method for the determination of corrosion rate at short-time intervals. The results of corrosion of mild steel in 10% HC1 solution with and without NTMP inhibitor at short-time intervals have been reported. The corrosion inhibition efficiency of NTMP is 93% after 24 h. Manish Gupta, Jyotsna Mishra, and K. S. Pitre Copyright © 2013 Manish Gupta et al. All rights reserved. Corrosion Behavior and Adsorption Thermodynamics of Some Schiff Bases on Mild Steel Corrosion in Industrial Water Medium Mon, 16 Sep 2013 09:54:13 +0000 The inhibition performance and adsorption behavior of (E)-2-(3-nitrobenzylidene) hydrazine carbothioamide (SB1) and (E)-2-(4-(dimethylamino) benzylidene) hydrazine carbothioamide (SB2) on mild steel corrosion in industrial water medium have been investigated by gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results revealed that inhibition efficiency depends on both the concentration of the inhibitors and temperature of the system. Increasing temperature reduces the inhibition efficiency of both inhibitors. Polarization studies indicated that these compounds behave as mixed type of inhibitors. The adsorption of both inhibitors was spontaneous and followed Langmuir adsorption isotherm. Thermodynamic parameters are calculated and discussed. The relation between inhibition efficiency and molecular structures of SB1 and SB2 was discussed by considering quantum chemical parameters. The surface adsorbed film was characterized by scanning electron microscopy (SEM). S. S. Shivakumar and K. N. Mohana Copyright © 2013 S. S. Shivakumar and K. N. Mohana. All rights reserved.