1) The document studied the corrosion behavior of magnesium and its alloys AZ91, AM50, and AM60 in a 0.5M Na2SO4 solution using potentiodynamic polarization curves.
2) The results showed magnesium had poor corrosion resistance and lacked passivation, while the alloys had improved corrosion resistance with the corrosion potential shifting positively.
3) AM50 and AM60 exhibited the best corrosion resistance due to the formation of a protective surface layer containing manganese and aluminum oxides/hydroxides, which inhibited anodic dissolution and galvanic corrosion. Manganese was particularly effective at improving corrosion resistance.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Corrosion Behaviour of 6061 Al-SiC Composites in KOH MediumEditor IJCATR
The present research work deals with the corrosion behaviour of 6061 Al-15% (vol) SiC(P) composites. The addition of the
reinforcement like SiC to Aluminium has been reported to decrease the corrosion resistance of the matrix due to several reasons, one
of them being galvanic action between the reinforcement and the matrix. In the present work, the corrosion behaviour of 6061 Al-15%
(vol) SiC(P) composites in KOH at different concentration (0.5M, 1M, 1.5M) and different temperature (300C, 350C, 400C, 450C, 500C)
was determined by Tafel extrapolation technique. The inhibition action of 8-Hydroxyquinoline on corrosion behaviour of 6061 Al-
15% (vol) SiC(P) composites in KOH at different concentration of inhibitor (200ppm, 400ppm); different concentration of medium
(0.5M, 1M,1.5M) and different temperature (300C, 350C, 400C, 450C, 500C) was investigated. The results indicate that corrosion rate
of Al-SiC composite in KOH increases as the concentration of medium increases and also as temperature of medium increases. The
results indicate that the inhibitor is moderately effective in inhibiting the corrosion of 6061 Al-15% (vol) SiC(P) composites. As the
inhibitor concentration increases, the corrosion rate decreases. The surface morphology of the metal surface was investigated using
scanning electron microscope (SEM). Activation energy was evaluated using Arrhenius equation, and enthalpy of activation and
entropy of activation values were calculated using transition state equation
Comparison of corrosion behaviour of commercial aluminium engine block and pi...msejjournal
The corrosion behavior of commercial aluminium alloy engine block and piston was investigated in 3.5% NaCl solution. The study was done by conventional gravimetric measurements and complemented by scanning electron microscopy (SEM) and X-ray analyzer (EDX) investigations. The results obtained indicate that the alloys suffers a process of corrosion localized to the area surrounding the precipitates of the Al (Si, Mg) and Al-Mg, which resulted in hemispherical pits. No evidence was found of the formation of crystallographic pitting for exposure times up to 54 days. Gravimetric analysis confirmed that with varying exposure periods the weight loss of the alloys increases and the normal corrosion rate profile of an initial steep rise followed by subsequent fall were observed for both alloys. The rate of corrosion of piston was found to be lower than that of engine block due to presence of Ni and lower percentages of Fe in aluminium piston alloy.
In the present investigation the corrosion measurements were carried out in 5% NaCl
aqueous solution, 2.5% HCl. solution for predetermined time intervals and varying
percentage concentrations of HCl solution at room temperature. Kinetics of corrosion
effect on samples of Al-Zn alloy, Al-Zn –5wt% flyash and silicon carbide particles and
Al-Zn –10wt% flyash and silicon carbide particles as reinforcement in composite are
studied.
Inhibition of Sulphuric Acid Corrosion of Mild Steel by Surfactant and Its Ad...IOSR Journals
Abstract: The corrosion inhibition effect of surfactant, N,N-Dimethyl-N-(2-Phenoxyethyl)dodecan-1- aminiumbromide(DPDAB) on mild steel corrosion in 0.5M Sulphuric acid was investigated by weight loss, potentiodynamic polarization and Electrochemical impedance spectroscopic techniques. DPDAB is an excellent inhibitor and its inhibition efficiency increases with increase in concentration and maximum inhibition efficiency was observed above the critical micelle concentration (CMC). The polarization curves reveal that DPDAB acts as mixed type inhibitor with predominantly of anodic type. The corrosion inhibition efficiency of DPDAB increases with increase in concentration and decreases with increase in temperature from 298K to 308K and then increases and shows maxima at 318K and then decreases at 328K.. The adsorption of the inhibitor on the mild steel in 0.5M H2SO4 was found to obey Langmuir’s adsorption isotherm. Scanning electronic microscopy (SEM) confirmed the existence of an adsorbed protective film on the metal surface. The kinetic and thermodynamic parameters were calculated and discussed.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Corrosion Behaviour of 6061 Al-SiC Composites in KOH MediumEditor IJCATR
The present research work deals with the corrosion behaviour of 6061 Al-15% (vol) SiC(P) composites. The addition of the
reinforcement like SiC to Aluminium has been reported to decrease the corrosion resistance of the matrix due to several reasons, one
of them being galvanic action between the reinforcement and the matrix. In the present work, the corrosion behaviour of 6061 Al-15%
(vol) SiC(P) composites in KOH at different concentration (0.5M, 1M, 1.5M) and different temperature (300C, 350C, 400C, 450C, 500C)
was determined by Tafel extrapolation technique. The inhibition action of 8-Hydroxyquinoline on corrosion behaviour of 6061 Al-
15% (vol) SiC(P) composites in KOH at different concentration of inhibitor (200ppm, 400ppm); different concentration of medium
(0.5M, 1M,1.5M) and different temperature (300C, 350C, 400C, 450C, 500C) was investigated. The results indicate that corrosion rate
of Al-SiC composite in KOH increases as the concentration of medium increases and also as temperature of medium increases. The
results indicate that the inhibitor is moderately effective in inhibiting the corrosion of 6061 Al-15% (vol) SiC(P) composites. As the
inhibitor concentration increases, the corrosion rate decreases. The surface morphology of the metal surface was investigated using
scanning electron microscope (SEM). Activation energy was evaluated using Arrhenius equation, and enthalpy of activation and
entropy of activation values were calculated using transition state equation
Comparison of corrosion behaviour of commercial aluminium engine block and pi...msejjournal
The corrosion behavior of commercial aluminium alloy engine block and piston was investigated in 3.5% NaCl solution. The study was done by conventional gravimetric measurements and complemented by scanning electron microscopy (SEM) and X-ray analyzer (EDX) investigations. The results obtained indicate that the alloys suffers a process of corrosion localized to the area surrounding the precipitates of the Al (Si, Mg) and Al-Mg, which resulted in hemispherical pits. No evidence was found of the formation of crystallographic pitting for exposure times up to 54 days. Gravimetric analysis confirmed that with varying exposure periods the weight loss of the alloys increases and the normal corrosion rate profile of an initial steep rise followed by subsequent fall were observed for both alloys. The rate of corrosion of piston was found to be lower than that of engine block due to presence of Ni and lower percentages of Fe in aluminium piston alloy.
In the present investigation the corrosion measurements were carried out in 5% NaCl
aqueous solution, 2.5% HCl. solution for predetermined time intervals and varying
percentage concentrations of HCl solution at room temperature. Kinetics of corrosion
effect on samples of Al-Zn alloy, Al-Zn –5wt% flyash and silicon carbide particles and
Al-Zn –10wt% flyash and silicon carbide particles as reinforcement in composite are
studied.
Inhibition of Sulphuric Acid Corrosion of Mild Steel by Surfactant and Its Ad...IOSR Journals
Abstract: The corrosion inhibition effect of surfactant, N,N-Dimethyl-N-(2-Phenoxyethyl)dodecan-1- aminiumbromide(DPDAB) on mild steel corrosion in 0.5M Sulphuric acid was investigated by weight loss, potentiodynamic polarization and Electrochemical impedance spectroscopic techniques. DPDAB is an excellent inhibitor and its inhibition efficiency increases with increase in concentration and maximum inhibition efficiency was observed above the critical micelle concentration (CMC). The polarization curves reveal that DPDAB acts as mixed type inhibitor with predominantly of anodic type. The corrosion inhibition efficiency of DPDAB increases with increase in concentration and decreases with increase in temperature from 298K to 308K and then increases and shows maxima at 318K and then decreases at 328K.. The adsorption of the inhibitor on the mild steel in 0.5M H2SO4 was found to obey Langmuir’s adsorption isotherm. Scanning electronic microscopy (SEM) confirmed the existence of an adsorbed protective film on the metal surface. The kinetic and thermodynamic parameters were calculated and discussed.
The inhibition effect of hydralazine hydrochloride on corrosion of mild steel...Premier Publishers
The inhibition effect of the Hydralazine hydrochloride for mild steel corrosion in 1M HCl has been investigated. Polarization measurement indicates that the Hydralazine hydrochloride act as mixed-type inhibitor, which gives a maximum inhibition efficiency around 72 %. Electrochemical impedance spectroscopy was used to investigate the mechanism of corrosion inhibition gives around 76 % due to the formation of electrical double layer. Thermodynamic parameter such as ΔG0 ads value was obtained as -30.22 KJ/mol indications that inhibitor shows its inhibition effect due to the chemisorptions process. Scanning electron microscopic images gives a visual idea about the formation of the protective film on the mild steel surface to reduce the corrosion rate. So that the Hydralazine hydrochloride acts as an efficient mixed type corrosion inhibitor for mild steel corrosion in acid media.
Corrosion Inhibition of Carbon Steel In Sulfuric Acid by Sodium CaprylateIJERA Editor
The interaction of a sodium salt of octanoic acid, sodium caprylate (SC), with a carbon steel (CS) surface was
investigated, using range of experimental techniques. It was shown that SC acts as a good CS general corrosion
inhibitor, yielding a maximum corrosion inhibition efficiency of 77%. This high inhibition efficiency is
maintained even at higher temperatures. It was determined that SC inhibits both partial corrosion reactions, and
can thus be considered to be a mixed-type inhibitor. The adsorption of SC on the CS surface was described by
the Langmuir adsorption isotherm. It was found that this process is spontaneous, irreversible and driven by the
entropy gain. The CS surface morphology was studied by SEM and it was demonstrated that SC is a very
effective general corrosion inhibitor of CS. This also was confirmed by contact angle measurements which
showed that the CS surface became more hydrophobic when the SC was added to the solution.
The synthesis and characterization of three new metal chalcogenide aerogels, Chalcogels,
AFe3Zn3S17 (A= Na, K, or Rb) is described. Alkali metal polychalcogenides (Na2S5, K2S5, or Rb2S5)
reactwith metal acetate like Fe(OAc)2 and Zn(OAc)2in formamide solutionforming extended polymeric
frameworks by gelation. Chalcogels obtained aftersupercritical drying have BET surface areas of
430, 444, and 435 m
2
/g for NaFe3Zn3S17, KFe3Zn3S17, and RbFe3Zn3S17, respectively. The effect of the
counter ions (K, Na, and Rb) wasstudied by examined the adsorption capacities of the resulting
chalcogels toward different gases and volatile organic compounds. The measurements showed that
CO2 and toluene adsorption capacities increase with the polarizability of the surface atoms in the
following order: Rb chalcogel> K chalcogel> Na chalcogel.This finding reveals a trend based on
cation size and acid–base surface properties that might have a significant impact on altering
adsorptive properties of chalcogels by using more polarizable counter ions.
International Refereed Journal of Engineering and Science (IRJES) is a peer reviewed online journal for professionals and researchers in the field of computer science. The main aim is to resolve emerging and outstanding problems revealed by recent social and technological change. IJRES provides the platform for the researchers to present and evaluate their work from both theoretical and technical aspects and to share their views.
www.irjes.com
Experimental and theoretical investigations of some pyrazolo-pyrimidine deriv...Al Baha University
The anticorrosion performance of three pyrazolo-pyrimidine derivatives, namely, 4-amino pyrazolo-pyrimidine
(APP), 4-hydroxy pyrazolo-pyrimidine (HPP), and 4-mercapto pyrazolo-pyrimidine (MPP) on copper in 0.5M
H2SO4 solution have been investigated using electrochemical, surface analysis, as well as theoretical techniques.
The results indicate that these inhibitors have largely inhibited the corrosion of copper and the inhibition efficiency
increased with increasing concentration. Moreover, the inhibitors adsorb on copper surface following
Langmuir adsorption isotherm. XPS analysis were performed for describing the bonding characteristics between
inhibitors and copper substrate. Furthermore, DFT and molecular dynamics simulation calculations were applied
to further explain the anti-corrosion mechanism.
Studies on Corrosion Characteristics of Carbon Steel Exposed to Na2CO3, Na2SO...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
THE CAUSE OF METALLIC CORROSION IN CRUDE OILSBerklin
Metallic corrosion is a severe interrogation regarding most of industrial applications of metals such as the industry of crude oil refining because of the foremost role of metals. The term of corrosion is usually explained as the formation of the metal oxide, sulfide, hydroxide or any compound related with a carboxylic group on the surface due to the impact of the surrounded conditions. The content of sulfur, acidity, mercaptans and salt content are the well ascertained corrosive properties of crude oils also the chemical composition of metals acquit oneself the fundamental preface for the corrosion. The surveillance of the comparison of corrosive capabilities of Murban and Das Blend crude oils in front of seven different types of ferrous metals that used in Sri Lankan refining industry was the dominant intention of this research. The chemical composition of used metals were determined by XRF detector while testing the contents of sulfur, acidities, contents of mercaptans and salt contents with respect to both crude oils simultaneously. Batches of well cleaned and equal sized metal pieces were immersed in both crude oils separately and the corrosion rate of each type of metal piece was determined after 15, 30 and 45 days from the immersion by weight loss method under the observations through the optical microscope. The ferrous and copper concentrations of each crude oil sample were tested while testing the variation of the hardness of each metal as a confirmation stage. According to results there were found relatively higher amount of sulfur, mercaptans, acids and lower amount of salt in Das Blend than Murban although relatively higher corrosion rates of most of metals in the Murban than the Das Blend. The slight reduction of hardness in each metal piece was found while observing significant concentration of ferrous and copper from some of crude oil samples.
The inhibition effect of hydralazine hydrochloride on corrosion of mild steel...Premier Publishers
The inhibition effect of the Hydralazine hydrochloride for mild steel corrosion in 1M HCl has been investigated. Polarization measurement indicates that the Hydralazine hydrochloride act as mixed-type inhibitor, which gives a maximum inhibition efficiency around 72 %. Electrochemical impedance spectroscopy was used to investigate the mechanism of corrosion inhibition gives around 76 % due to the formation of electrical double layer. Thermodynamic parameter such as ΔG0 ads value was obtained as -30.22 KJ/mol indications that inhibitor shows its inhibition effect due to the chemisorptions process. Scanning electron microscopic images gives a visual idea about the formation of the protective film on the mild steel surface to reduce the corrosion rate. So that the Hydralazine hydrochloride acts as an efficient mixed type corrosion inhibitor for mild steel corrosion in acid media.
Corrosion Inhibition of Carbon Steel In Sulfuric Acid by Sodium CaprylateIJERA Editor
The interaction of a sodium salt of octanoic acid, sodium caprylate (SC), with a carbon steel (CS) surface was
investigated, using range of experimental techniques. It was shown that SC acts as a good CS general corrosion
inhibitor, yielding a maximum corrosion inhibition efficiency of 77%. This high inhibition efficiency is
maintained even at higher temperatures. It was determined that SC inhibits both partial corrosion reactions, and
can thus be considered to be a mixed-type inhibitor. The adsorption of SC on the CS surface was described by
the Langmuir adsorption isotherm. It was found that this process is spontaneous, irreversible and driven by the
entropy gain. The CS surface morphology was studied by SEM and it was demonstrated that SC is a very
effective general corrosion inhibitor of CS. This also was confirmed by contact angle measurements which
showed that the CS surface became more hydrophobic when the SC was added to the solution.
The synthesis and characterization of three new metal chalcogenide aerogels, Chalcogels,
AFe3Zn3S17 (A= Na, K, or Rb) is described. Alkali metal polychalcogenides (Na2S5, K2S5, or Rb2S5)
reactwith metal acetate like Fe(OAc)2 and Zn(OAc)2in formamide solutionforming extended polymeric
frameworks by gelation. Chalcogels obtained aftersupercritical drying have BET surface areas of
430, 444, and 435 m
2
/g for NaFe3Zn3S17, KFe3Zn3S17, and RbFe3Zn3S17, respectively. The effect of the
counter ions (K, Na, and Rb) wasstudied by examined the adsorption capacities of the resulting
chalcogels toward different gases and volatile organic compounds. The measurements showed that
CO2 and toluene adsorption capacities increase with the polarizability of the surface atoms in the
following order: Rb chalcogel> K chalcogel> Na chalcogel.This finding reveals a trend based on
cation size and acid–base surface properties that might have a significant impact on altering
adsorptive properties of chalcogels by using more polarizable counter ions.
International Refereed Journal of Engineering and Science (IRJES) is a peer reviewed online journal for professionals and researchers in the field of computer science. The main aim is to resolve emerging and outstanding problems revealed by recent social and technological change. IJRES provides the platform for the researchers to present and evaluate their work from both theoretical and technical aspects and to share their views.
www.irjes.com
Experimental and theoretical investigations of some pyrazolo-pyrimidine deriv...Al Baha University
The anticorrosion performance of three pyrazolo-pyrimidine derivatives, namely, 4-amino pyrazolo-pyrimidine
(APP), 4-hydroxy pyrazolo-pyrimidine (HPP), and 4-mercapto pyrazolo-pyrimidine (MPP) on copper in 0.5M
H2SO4 solution have been investigated using electrochemical, surface analysis, as well as theoretical techniques.
The results indicate that these inhibitors have largely inhibited the corrosion of copper and the inhibition efficiency
increased with increasing concentration. Moreover, the inhibitors adsorb on copper surface following
Langmuir adsorption isotherm. XPS analysis were performed for describing the bonding characteristics between
inhibitors and copper substrate. Furthermore, DFT and molecular dynamics simulation calculations were applied
to further explain the anti-corrosion mechanism.
Studies on Corrosion Characteristics of Carbon Steel Exposed to Na2CO3, Na2SO...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
THE CAUSE OF METALLIC CORROSION IN CRUDE OILSBerklin
Metallic corrosion is a severe interrogation regarding most of industrial applications of metals such as the industry of crude oil refining because of the foremost role of metals. The term of corrosion is usually explained as the formation of the metal oxide, sulfide, hydroxide or any compound related with a carboxylic group on the surface due to the impact of the surrounded conditions. The content of sulfur, acidity, mercaptans and salt content are the well ascertained corrosive properties of crude oils also the chemical composition of metals acquit oneself the fundamental preface for the corrosion. The surveillance of the comparison of corrosive capabilities of Murban and Das Blend crude oils in front of seven different types of ferrous metals that used in Sri Lankan refining industry was the dominant intention of this research. The chemical composition of used metals were determined by XRF detector while testing the contents of sulfur, acidities, contents of mercaptans and salt contents with respect to both crude oils simultaneously. Batches of well cleaned and equal sized metal pieces were immersed in both crude oils separately and the corrosion rate of each type of metal piece was determined after 15, 30 and 45 days from the immersion by weight loss method under the observations through the optical microscope. The ferrous and copper concentrations of each crude oil sample were tested while testing the variation of the hardness of each metal as a confirmation stage. According to results there were found relatively higher amount of sulfur, mercaptans, acids and lower amount of salt in Das Blend than Murban although relatively higher corrosion rates of most of metals in the Murban than the Das Blend. The slight reduction of hardness in each metal piece was found while observing significant concentration of ferrous and copper from some of crude oil samples.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
This paper presents a study that investigates the corrosion behavior of annealed 2205 duplex stainless steel in sulphuric acid environment. Duplex 2205 stainless steel black bar in ASTM A276 was obtained and annealed in solite furnace for 45 minutes. A control sample which was not heat treated was also prepared. The annealed and the control samples which were metallographically prepared were then analyzed for corrosion behavior in sulphuric acid using potentiodynamic test/analysis. The potentiodynamic polarization plot generated showed that the annealed samples exhibit less corrosion resistance than the untreated samples, indicating that annealing heat treatment reduces the corrosion resistance of 2205 duplex stainless steel in sulphuric acid.
Inhibition, kinetic and thermodynamic effects of new Azo derivatives on iron ...Al Baha University
This investigation is designed to apply an advanced kinetic-thermodynamic model on the experimental data obtained from acidic and alkaline corrosion of iron using mono- and bis-azo dyes as corrosion inhibitors. The inhibition properties of the tested azo dyes on corrosion of iron in HNO3 and NaOH media were analyzed by gravimetric, thermometric and polarization measurements. The three studied methods gave consistent results. Polarization study showed that all the inhibitors are mixed type in acidic, act mainly as cathodic in alkaline solution. The synthesized azo dye derivatives exhibit good inhibition properties, obeys the Frumkin adsorption isotherm. The large values of the change in the standard free energy of adsorption (∆Goads), equilibrium constant (Kads) and binding constant (Kb) revealed that the reactions proceed spontaneously and result in highly efficient physisorption mechanism and stronger electrical interaction between the double layer existing at the phase boundary and the adsorbing molecules. The inhibition efficiency depends on the number of adsorption oxygen sites (OH and OMe groups), their charge density and π-electron clouds. The inhibition efficiency evaluated via theoretical methods was well accorded with reported experimental ones, following the same order as: -naphthyl- ligand > -naphthyl>p-anisdine>p-toluidine >o-toluidine >m-toluidine derivative. This research might provide a theoretical inhibition performance evaluation approach for homologous inhibitors.
THE EFFECT OF LSM CORROSION PROTECTION ON AL ALLOYSIAEME Publication
Laser surface treatment has been recognized as a useful method for corrosion protection of surfaces as a result of improved microstructure/phase formation and compositions. Therefore, Laser surface treatment techniques, including laser surface melting (LSM) has been the subject of considerable interest as a means of enhancing the corrosion performance of aluminum alloys.
In this research, disc samples of (7075, 6061 and 5083) aluminum alloys have been prepared, polarization tests were carried out under static condition in a different concentration of NaCl solution (1.5, 2.5, 3.5) %wt at 25oC.
Investigative studies on the inhibitive effects of Newbouldialaevis extracts ...researchinventy
The inhibitive effects ofNewbouldiaLaevis (NL) leaf extract and magnetic field on copper corrosion in 0.5M H2SO4 aqueous solution were investigated experimentally by gravimetric technique and theoretically using Quantum Chemical calculations. The results show that both NL and the magnetic field caused reduction in corrosion rate. The inhibition efficiency increased with concentration. The magnetic field caused greater increase in the inhibition efficiency. Temperature increase caused a decrease in inhibition efficiency. The activation energy is low and oscillates, possibly due to error factor from non-linearity of the Arrhenius plot. Among the tested isotherms, Langmuir has the highest correlation coefficient of 0.9963 and 0.7935 with and without magnet field respectively. The magnetic field increased the change in free energy, caused the reaction to become spontaneous, one mole of the inhibitor to replace 4 moles of water mole while reducing the number of monolayer of the inhibitor on the metal. The quantum chemical calculations performed on newbouldiaquinone and lapacholconstituents of NL showed that lapachol contributed more to the inhibition efficiency due its low binding energy, high dipole moment, chemical softness and fractional electron transfer. The magnetic field and temperature played opposite roles.
Some factors affecting on the behavior ofsteel electrode in citric acid solut...IJERA Editor
Potential-time curves are constructed for the steel electrode in naturally aerated citric acid solutions devoid of
and containing some aggressive and inhibitive compounds. Cl- and SO4
2- ions cause the destruction of passivity
and initiation of pitting corrosion. The rate of oxide film growth by citric acid and oxide film destruction by Cl-
and SO4
2- ions follows a direct logarithmic law as evident from the linear relationships between the open-circuit
potential and the logarithm of immersion time. Urea, phenylhydrazine and 1,2-phenylenediamine compounds
inhibit the pitting corrosion of steel. The rate of oxide film healing and thickening increases with their
concentrations. In presence of constant inhibitor concentration, the efficiency of pitting inhibition increases in
the order: (weak) urea<phenylhydrazine><1,2-phenylenediamine(strong).
Corrosion Inhibition of Carbon Steel in Chloride and Sulfate SolutionsIJERA Editor
Corrosion is a major problem in industry and in infrastructure; a huge sum of expenditure every year is spent on
preventing, retarding, and repairing its damages. This work studies the engineering of an inhibitor for carbon
steel metal used in the cooling systems containing high concentration of chloride and sulfate ions. For this
purpose, the synergy between the dichromate, molybdate and nitrite inhibitors is examined and optimized to the
best results. Moreover, care was taken that the proposed inhibitor is compliant with the environmental laws and
regulations.
Similar to A study of the corrosion behavior of magnesium and its alloys (20)
A study of the corrosion behavior of magnesium and its alloys
1. Chemistry and Materials Research www.iiste.org
ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online)
Vol.6 No.6, 2014
1
A Study of the Corrosion Behavior of Magnesium and its Alloys in
Aggressive Environment
Amel Boukhouiete
Laboratory of Physical Metallurgy and material properties, University of Badji Mokhtar, PO 12, Annaba,
23000 Algeria.
E-mail: amelboukhouiete@yahoo.fr
Zoubida HABES (Corresponding author)
Laboratory of LASEA, University of Badji Mokhtar, PO 12, Annaba, 23000 Algeria.
E-mail: zoubida.habes@hotmail.com
Abstract
Magnesium presents indeed a low corrosion resistance [1, 2, 3, 4]. Moreover the behavior of this metal and its
alloys is still poorly known in many corrosive environments which limit its applications. Magnesium is
particularly sensitive to galvanic corrosion. The presence of impurities (Fe, Ni, Cu, Cr ...) in its matrix with
potential higher than that of Magnesium promotes the reduction reactions, especially that of hydrogen and thus
generates the galvanic corrosion of magnesium [1, 5]. From its purity depends its resistance to corrosion. The
use of alloying elements can improve the corrosion resistance of magnesium (and also the mechanical properties).
A beneficial effect of aluminum and manganese on the corrosion resistance of magnesium has been
demonstrated [4]. The objective of this work was to evaluate the corrosion of Mg and its alloys by
electrochemical method (potentiodynamic) in an aqueous solution of 0.5 M Na2SO4.
Keywords: Corrosion, magnesium, protection, passivation, alloying elements.
1. Introduction
At the dawn of XXI century, ultra-light materials have greatly developed. Among these, magnesium in which
resources are considered inexhaustible is extremely promoter for many applications, they are in the field of
automotive, aerospace, industrial electronics and armament. The desire to decrease by 30% the weight of
vehicles in the coming years have significantly increased number of application of these alloys. Its low density
(1.7) place it before aluminum (2.7), titanium (4.7) or steel (8). Magnesium alloys appear very interesting, even
if they are still little used, compared to aluminum alloys for industrial applications, mainly because of their
sensitivity to corrosion.
2. Experimental Procedure
The materials used in this study are: pure Mg, AZ91 alloys (Al 9%, Zn1%), AM50 (5% Al, 0.13% Mn) and
AM60 (6% Al, 0.13% Mn). Samples of useful surface 0.2 cm2, the active surface of samples is polished with
sandpaper and cleaned with compressed and dry air.
The electrochemical tests were carried out in an aqueous solution of sodium sulfate Na2SO4 (monapur for
analysis MW = 142.02) with concentration of 0.5 M at ambient temperature and at atmospheric pressure.
The assembly used is a conventional electrochemical assembly with three electrodes: The electrode of reference
with saturated mercurous sulfate (E = 640 mV / SHE) in contact with the solution through an electrolyte bridge
(Hg2/Hg2SO4), the platinum auxiliary electrode and a working electrode. In order to stabilize the free potential
of magnesium, an immersion of 25 minutes of working electrodes in the solution of Na2SO4 is performed.
All curves log I = f (E) were drawn from the potential -2.45 V to -1.50 V / E.N.H. The potential sweep rate is 0.5
mV/s. This speed was taken by considering that the evolution of the potential is low (less than 20 mV) in the
path of a curve I = f (E).
The apparatus used was a potentiostat-galvanostat EGG273A controlled by a computer DELL using M352
corrosion software.
2. Chemistry and Materials Research www.iiste.org
ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online)
Vol.6 No.6, 2014
2
3 Results and Discussion
The curves of cathodic and anodic polarization of pure magnesium and its alloys AZ91, AM50 and
AM60 (in aqueous 0.5 M Na2SO4 not deaerated), drawn from the potential-2.5V to -1.950V are given on the
Figure I. We notice an increase in pH of the solution Na2SO4 when drawing curves from the value of 6.4 to 9.5
and the observation of a gassing probably of dihydrogen.
Figure 1 : Anodic and cathodic polarization curves of pure Mg and its alloys. Environment: Na2SO4 0.5 M
Na2SO4, not deaerated.
The cathodic curve of pure magnesium (a) has two portions. The first portion characterized by a Tafel slope of
the order of 180 mV and a quasi-linear decrease of the cathodic current. The second portion begins to-2.188V
shows a sharp decrease of cathodic current and the appearance of an anodic current.
The slope of the linear portion of the cathodic curve is frequently found for the reaction of reduction H
+ ions or molecules of H2O [6]. In fact, when drawing the cathodic curve, a release of gas is observed and an
increase in pH that may correspond to the reduction of water and proton.
The film formation by interaction between the magnesium and ions from the water during the
immersion period prior to measurement may be considered. This film may change during the cathodic
polarization. Presumably during the cathodic polarization, hydrogen adsorbed on the surface, from the reduction
of water is evacuated to the solution.
Locally, the OH-ions product generate an increase in pH, and probably the strengthening of the layer of
magnesium hydroxide. On the anodic curve, we observe : a first portion which is characterized by an increase in
the anodic current, a second portion starting at about-2.075V is manifested by a quasi-linear evolution, a third
portion shows an increase in anodic current from the potential about-1.975V, we note that there is a lack of
passivation of magnesium.
The increase in anodic current in the first portion reflects a destabilization of the surface layer with
weak protective properties that is present on the surface of magnesium. This destabilization can be attributed to a
competition between different types of surface compounds such as hydroxides and oxides. The sudden increase
in the anodic current in the third portion may be associated with an important anodic dissolution leading to the
formation of a non-protective discontinuous corrosion layer.
Moreover, the polarization curves (b, c and d) traced on the magnesium alloys AZ91, AM50 and AM60 shows
the movement of corrosion potential of them towards more positive values. This must be associated on the one
hand to the inhibition of the anodic dissolution of magnesium and on the other hand the movement of the
reaction of cathodic reduction to more negative values. Improved corrosion behavior of AZ91 alloys (curve b)
compared to pure magnesium can be explained by the formation of protective oxides on the surface of Mg-Al
alloys [4]. It has been shown that the aluminum introduced into the magnesium alloy with 9% to 29% allows an
increase in corrosion resistance [4,7]. Figure 1 also shows that AM50 alloys (curve c) and AM 60 (curve d) have
better corrosion resistance than AZ91 alloy. In fact, there was a significant decrease in dissolution for samples
3. Chemistry and Materials Research www.iiste.org
ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online)
Vol.6 No.6, 2014
3
AM50 and AM60. This could be due to the formation of a protective surface layer, some authors argue the
inhibition of anodic dissolution (pitting corrosion and galvanic corrosion) of magnesium: the participation of
aprotic ions such as MnOx to the anodic reaction forming stable mixed oxides of magnesium and manganese on
the surface [1,4,7,8]. In addition, the manganese is part of the transition metals, known as <<valve metal>>.
These metals are able to develop on their surface a protective oxide layer vis-à-vis to corrosion.
On the other hand, it is known that iron traces or other transition metals such as copper, nickel and
cobalt generate an increase in the corrosion rate of pure magnesium due to a low overvoltage of the hydrogen on
these metals [9]. These sites of impurities cause the activation of the reduction cathodic reaction with release of
hydrogen and promote the anodic reaction of magnesium corrosion. Manganese is an improvement of the
corrosion resistance of Mg-Al alloys by lowering the difference of galvanic potential between the anode sites
(the matrix) and cathodic sites (impurity) and by improving the passive state of the matrix [10]. In the presence
of aluminum and manganese, the iron is trapped in the form of intermetallic AlMnFe [4,7, 11]. Most studies on
the role of Mn on the impurity concentration have focused on the iron, the main impurity of Mg. A similar effect
was shown for copper and Ni, whose concentrations are also strongly lowered in the presence of Mn.
Encompassing the iron particles, copper or nickel that are found in trace amounts, the manganese reduces their
harmful character.
4 Conclusion
In this work, we studied the corrosion of pure magnesium and its alloys in a solution of Na2SO4 in an
area of slightly acidic pH to slightly alkaline by the potentiodynamic method.
The results show the temporal evolution of pH to alkaline values and a high sensitivity to corrosion of pure
magnesium leading to the anodic dissolution and the formation of a discontinuous corrosion and not protective
layer.
On the other hand we have highlighted the role of manganese and aluminum in improving the resistance to
corrosion of magnesium. The results obtained are in agreement with numerous studies to clarify the influence of
alloying elements on the corrosion of magnesium. However, manganese appears to be far more effective for
improving the corrosion resistance. This is mainly due to the formation of complex oxides and hydroxides of this
element with magnesium which are relatively insoluble in aggressive electrolytes and which modify the
electrochemical reactivity of the surface of magnesium [9].
Moreover, in the presence of manganese and aluminum, the iron is trapped in the form of intermetallic
AlMnFe [4,11]. The alloy thus formed has a better resistance to corrosion.
Given the encouraging results obtained with AM50 and AM60 alloys, these alloys can probably be
improved by an optimized composition.
References
1. X.Hallopeau, T.Beldjoudi, C.Fiaud and L.Robbiola, corrosion Reviews 16,1-2,27 (1998)M. Ben Rabha,
M.F. Boujmil, M. Saadoun, B. Bessaïs, Eur. Phys. J. Appl. Phys. (to be published)
2. N. LeBozec, M. Jonsson, D. Thierry, Corrosion 60(4) (2004) 356.
3. G. Baril, N. Pebere, Corros. Sci. 43(2001) 471.
4. K.Nisancioglu. corrosion. 43,291 (1987)
5. Special Issue : corrosion resistance of magnesium alloys Reviews, 16, No1-2 (1998)
6. G. Song, A.Atrens, D. St John, J. Nairn and Y. Li, Corros. Sci.,39, 5,855, (1997).
7. T.Beldjoudi, C.Fiaud and L.Robbiola, Corrosion Science, 49,9,738 (1993).
8. G. Song, A.Atrens, D. St John, X. Wu and J. Nairn, Corrosion. Science, 39,10-11,1981(1981)
9. X.Hallopeau, Thèse de métallurgie et matériaux de l’université de ParisXI Orsay , (1996).
10. M.B. Ives, Y. C. Lu and J. L. Luo. Corros. Sci, 32, 91(1991).
11. G.L.Makar, J .Kruger, A. Joshi- TMS AIME- Meeting Phoenix, USA, 105, (1988)
12. CHEN Zhen-hua. Magnesiumalloys [M] Beijin; Chemical Industry Press, 2004; 36. (in Chinese)
4. The IISTE is a pioneer in the Open-Access hosting service and academic event
management. The aim of the firm is Accelerating Global Knowledge Sharing.
More information about the firm can be found on the homepage:
http://www.iiste.org
CALL FOR JOURNAL PAPERS
There are more than 30 peer-reviewed academic journals hosted under the hosting
platform.
Prospective authors of journals can find the submission instruction on the
following page: http://www.iiste.org/journals/ All the journals articles are available
online to the readers all over the world without financial, legal, or technical barriers
other than those inseparable from gaining access to the internet itself. Paper version
of the journals is also available upon request of readers and authors.
MORE RESOURCES
Book publication information: http://www.iiste.org/book/
IISTE Knowledge Sharing Partners
EBSCO, Index Copernicus, Ulrich's Periodicals Directory, JournalTOCS, PKP Open
Archives Harvester, Bielefeld Academic Search Engine, Elektronische
Zeitschriftenbibliothek EZB, Open J-Gate, OCLC WorldCat, Universe Digtial
Library , NewJour, Google Scholar