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Sample records for electrochemical corrosion behaviour

  1. Electrochemical corrosion behaviours of pulsed bias MSIP aluminum coating on depleted uranium surface

    International Nuclear Information System (INIS)

    Wang Qingfu; Zhang Pengcheng; Chen Lin; Liu Qinghe; Lang Dingmu; Wang Xiaohong

    2009-01-01

    Aluminum coating was prepared by magnetron sputtering ion plating (MSIP) with pulsed bias on depleted uranium surface. Its electrochemical corrosion behaviours were studied by electrochemical technology, scanning electron microscope (SEM) and X-ray energy dispersive spectroscope (EDS). The corrosion potential of aluminum coating (-534.8 mV) is higher than that of depleted uranium (-641.2 mV). The aluminum coating is a cathodic deposit to depleted uranium. Depleted uranium coated aluminum has much higher polarization resistance,greater magnitude of electrochemical impedance and much lower corrosion current than that of depleted uranium. The aluminum coating has a good corrosion resistance to depleted uranium. Corrosion characteristic of depleted uranium coated aluminum is a typical local corrosion. Meanwhile,the aluminum coating cracks and flakes off from depleted uranium substrate, which deteriorates its anti-corrosion property. Pseudo-diffusion layer on interface between aluminum coating and uranium substrate has some degree of anti-corrosion effect. (authors)

  2. ELECTROCHEMICAL BEHAVIOUR OF ENVIRONMENTALLY ...

    African Journals Online (AJOL)

    dell

    ABSTRACT. Electrochemical behaviour of Aloe secundiflora on carbon steel corrosion control in neutral and aerated soft water solutions have been investigated using electrochemical impedance spectroscopy and Tafel polarization techniques. The investigation was performed at different inhibitor concentrations under ...

  3. An ac impedance study of the corrosion behaviour of mild steel coated with electrochemically synthesized polyoxyphenylenes

    Energy Technology Data Exchange (ETDEWEB)

    Musiani, M.M.; Mengoli, G.; Pagura, C.

    1985-04-01

    Electrochemically synthesized polyoxphenylene coatings on mild steel exposed to NaCl or H2SO4 solutions were investigated by ac impedance measurements. The influence of coating cohesion, adhesion to substrate, and surface pretreatment on the corrosion behaviour of the samples is clarified.

  4. Corrosion behaviour of Alloy 800 in high temperature aqueous solutions: Electrochemical studies

    International Nuclear Information System (INIS)

    Olmedo, A.M.; Villegas, M.; Alvarez, M.G.

    1996-01-01

    The anodic behaviour and passivity breakdown of Alloy 800 in aqueous solutions of sodium chloride, sodium sulphate and sodium bicarbonate were studied by electrochemical techniques in the temperature range from 60 C to 280 C. The pitting resistance and pitting morphology of the alloy in chloride plus sulphate and chloride plus bicarbonate mixtures, at 60 C and 280 C, were also examined. Increasing bicarbonate or sulphate additions to chloride solutions shift the characteristic pitting potential of Alloy 800 to higher values, both at low and high temperatures. Changes in pitting morphology were observed in sulphate containing solutions while the morphology of the attack found in bicarbonate containing solutions was similar to that in pure chloride solutions. Finally, no localized or substantial generalized corrosion was detected in pure sulphate or bicarbonate solutions at any temperature. (orig.)

  5. Electrochemical noise evaluation of anodized aluminum. Comparative study against corrosion behaviour in the atmosphere

    Directory of Open Access Journals (Sweden)

    Betancourt, N.

    2003-12-01

    Full Text Available The present work reports the evaluation of aluminum and anodized aluminum by electrochemical noise, as a part of the PATINA/CYTED project of the working group Nº 5. A visual examination is also made. The samples were exposed at several Ibero-American atmospheres up to 2 years of exposure. Different thickness of anodized aluminum were evaluated. The electrochemical potential noise of the 5 μm unexposed sample (pattern showed a different behaviour to that showed by the other anodized specimens. This could be due to a slower sealed of the samples of higher thickness. The same behaviour was observed on the samples exposed at the rural station El Pardo. According to the visual examination, the samples of bare aluminum and those of anodized 5 μm thickness were the most affected by pitting corrosion in the highly polluted atmospheres. A good correlation between corrosion behaviour determined by visual examination and EN was obtained.

    Como parte de las investigaciones de la Red PATINA el grupo de trabajo Nº 5 dedicó su atención al comportamiento del aluminio desnudo y anodizado con diferentes espesores en diferentes atmósferas de Iberoamérica. En el presente trabajo se presenta una evaluación de patrones de aluminio 99,5 % de pureza desnudo y anodizado con espesores de 15 y 25 μm, mediante ruido electroquímico. Los resultados obtenidos se comparan con el comportamiento determinado en diferentes atmósferas durante un período de 2 años. El ruido de voltaje del patrón de 5 μm de espesor presenta un comportamiento diferente al de los restantes espesores, lo que coincide con una mayor susceptibilidad a la corrosión picadura de este primer anodizado. Se reportan también algunas diferencias en el ruido de corriente. Se concluye que mediante la utilización del ruido electroquímico es posible caracterizar el aluminio con respecto a su sensibilidad a la corrosión picadura en condiciones atmosféricas.

  6. The estimation of corrosion behaviour of ZrTi binary alloys for dental applications using electrochemical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mareci, Daniel [“Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, Iasi (Romania); Bolat, Georgiana, E-mail: georgiana20022@yahoo.com [“Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, Iasi (Romania); Chelariu, Romeu [“Gheorghe Asachi” Technical University of Iasi, Faculty of Materials Science and Engineering, Iasi (Romania); Sutiman, Daniel [“Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, Iasi (Romania); Munteanu, Corneliu [“Gheorghe Asachi” Technical University of Iasi, Faculty of Mechanical, Iasi (Romania)

    2013-08-15

    Titanium and zirconium are in the same group in the periodic table of elements and are known to have similar physical and chemical properties. Both Ti and Zr usually have their surfaces covered by a thin oxide film spontaneously formed in air. However, the cytotoxicity of ZrO{sub 2} is lower than that of TiO{sub 2} rutile. Treatments with fluoride are known as the main methods to prevent plaque formation and dental caries. The corrosion behaviour of ZrTi alloys with Ti contents of 5, 25 and 45 wt.% and cp-Ti was investigated for dental applications. All samples were tested by linear potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) performed in artificial saliva with different pH levels (5.6 and 3.4) and different fluoride (1000 ppm F{sup −}) and albumin protein (0.6%) contents. In addition, scanning electron microscopy (SEM) was employed to observe the surface morphology of the test materials after linear potentiodynamic polarisation. The corrosion current densities for the ZrTi alloys increased with the titanium content. The Zr5Ti and Zr25Ti alloys were susceptible to localised corrosion. The role that Ti plays as an alloying element is that of increasing the resistance of ZrTi alloy to localised corrosion. The presence of 0.6% albumin protein in fluoridated acidified artificial saliva with 1000 ppm F{sup −} could protect the cp-Ti and ZrTi alloys from attack by fluoride ions. - Highlights: • Electrochemical and corrosion behaviour of the new ZrTi alloys were investigated. • The passive behaviour for all the ZrTi alloys is observed. • Addition of Ti to Zr improves the corrosion resistance in some fluoridated saliva. • The presence of albumin could prevent the ZrTi alloys from attack by fluoride ions.

  7. Electrochemical corrosion of metallic biomaterials.

    Science.gov (United States)

    Pourbaix, M

    1984-05-01

    Methods of electrochemical thermodynamics (electrode potential-pH equilibrium diagrams) and electrochemical kinetics (polarization curves) may help to understand and predict the corrosion behaviour of metals and alloys in the presence of body fluids. A short review of the literature is given concerning some applications of such methods, both in vitro and in vivo, relating to surgical implants (stainless steels, chromium-cobalt-molybdenum alloys, titanium and titanium alloys) and to dental alloys (silver-tin-copper amalgams, silver-base and gold-base casting alloys, nickel-base casting alloys). Attention is drawn to the necessity of more basic research on crevice- and fretting-corrosion of surgical implant materials and dental alloys, and to the toxicity of corrosion products. A perfect understanding of the exact significance of electrode-potentials is essential for the success of such a task.

  8. Electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy study of the corrosion behaviour of galvanized steel and electroplating steel

    Energy Technology Data Exchange (ETDEWEB)

    Lebrini, M., E-mail: mlebrini@yahoo.fr [Laboratoire des Procedes d' Elaboration des Revetements Fonctionnels, PERF-LSPES UMR CNRS 8008, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Traisnel, M. [Laboratoire des Procedes d' Elaboration des Revetements Fonctionnels, PERF-LSPES UMR CNRS 8008, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Gengembre, L. [Unite de Catalyse et Chimie du solide UMR 8181 Bat C3, USTL, F-59655, Villeneuve d' Ascq Cedex (France); Fontaine, G. [Laboratoire des Procedes d' Elaboration des Revetements Fonctionnels, PERF-LSPES UMR CNRS 8008, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Lerasle, O.; Genet, N. [TOTAL France, Centre de Recherche de Solaize, Chemin du canal, BP 22, F-69360 Solaize (France)

    2011-02-01

    The efficiency of a formula containing 2-{l_brace}(2-hydroxyethyl)[(4-methyl-1H-1,2,3-benzotriazol-1-yl)methyl] amino{r_brace}ethanol (tolyltriazole) and decanoic acid as corrosion inhibitor for galvanized steel and electroplating steel in aqueous solution have been determined by electrochemical impedance spectroscopy (EIS) techniques. The experimental data obtained from this method show a frequency distribution and therefore a modelling element with frequency dispersion behaviour, a constant phase element (CPE) has been used. The corrosion behaviour in the presence of different concentration of decanoic acid (DA) in the formula was also investigated by EIS. Results obtained reveal that, the formula is a good inhibitor for galvanized steel and electroplating steel in aqueous solution, the better performance was obtained in the case of galvanized steel. The ability of the inhibitor to be adsorbed on the surface was dependent on the nature of metal. X-ray photoelectron spectroscopy surface analysis with inhibitor shows that it's chemisorbed at the galvanized and electroplating steel/aqueous solution interface.

  9. Corrosion behaviour of Ni in aprotic solvents an electrochemical, XPS and AFM study

    International Nuclear Information System (INIS)

    Bellucci, F.; Monetta, T.; Capobianco, G.; Deganello, A.; Glisenti, A.; Moretti, G.

    1998-01-01

    Electrochemical and X-ray photoelectron spectroscopic (XPS) techniques have been used to study the passivation of nickel in 0.1 M H 2 SO 4 DMF and ACN solutions with different water content. Electrochemical results indicate the anodic formation of a thin, poor protective layer and the possibility of salt precipitation onto the metallic surface. ARXPS results indicate that while in the anodic film formed in DMF, Ni(OH) 2 constitute the superficial component under which a discontinuous layer of NiO and NiSO 4 is present. Ni(OH) 2 and NiSO 4 are the more superficial constituents in the passivation layer formed in ACN, while NiO becomes prevalent in the underlying layers. AFM images show that in both the solvents the sample surface is very dishomogeneous with flakes and fractures. (orig.)

  10. Electrochemical studies of corrosion inhibitors

    Science.gov (United States)

    Danford, M. D.

    1990-01-01

    The effect of single salts, as well as multicomponent mixtures, on corrosion inhibition was studied for type 1010 steel; for 5052, 1100, and 2219-T87 aluminum alloys; and for copper. Molybdate-containing inhibitors exhibit an immediate, positive effect for steel corrosion, but an incubation period may be required for aluminum before the effect of a given inhibitor can be determined. The absence of oxygen was found to provide a positive effect (smaller corrosion rate) for steel and copper, but a negative effect for aluminum. This is attributed to the two possible mechanisms by which aluminum can oxidize. Corrosion inhibition is generally similar for oxygen-rich and oxygen-free environments. The results show that the electrochemical method is an effective means of screening inhibitors for the corrosion of single metals, with caution to be exercised in the case of aluminum.

  11. Electrochemical Measurement of Atmospheric Corrosion

    Science.gov (United States)

    DeArmond, Anna H.; Davis, Dennis D.; Beeson, Harold D.

    1999-01-01

    Corrosion of Shuttle thruster components in atmospheres containing high concentrations of nitrogen tetroxide (NTO) and water is an important issue in ground operations of bipropellant systems in humid locations. Measurements of the corrosivities of NTO-containing atmospheres and the responses of different materials to these atmospheres have been accomplished using an electrochemical sensor. The sensor is composed of alternating aluminum/titanium strips separated by thin insulating layers. Under high humidity conditions a thin film of water covers the surface of the sensor. Added NTO vapor reacts with the water film to form a conductive medium and establishes a galvanic cell. The current from this cell can be integrated with respect to time and related to the corrosion activity. The surface layer formed from humid air/NTO reacts in the same way as an aqueous solution of nitric acid. Nitric acid is generally considered an important agent in NTO corrosion situations. The aluminum/titanium sensor is unresponsive to dry air, responds slightly to humid air (> 75% RH), and responds strongly to the combination of humid air and NTO. The sensor response is a power function (n = 2) of the NTO concentration. The sensor does not respond to NTO in dry air. The response of other materials in this type of sensor is related to position of the material in a galvanic series in aqueous nitric acid. The concept and operation of this electrochemical corrosion measurement is being applied to other corrosive atmospheric contaminants such as hydrogen chloride, hydrogen fluoride, sulfur dioxide, and acidic aerosols.

  12. Contribution to the study of the electrochemical behaviour of titanium and of its industrial shores in sulphuric environment. Characteristics of their resistance to pitting corrosion in neutral and acid halogenous environment

    International Nuclear Information System (INIS)

    Petit, Jacques-Alain

    1975-01-01

    After a presentation of the general metallurgical, physical, and corrosion resistance characteristics of titanium and of its alloys, this research thesis presents the experimental means, discusses the influence of experimental conditions on the assessment of the electrochemical behaviour of titanium and of its alloys. It reports an investigation of the cathodic behaviour of non-alloyed titanium and notably the hydrogen release kinetics in a concentrated acid environment. It discusses the influence of alloy composition on their cathodic behaviour, addresses the anodic behaviour of titanium and of its alloys in sulphuric environment, and the pitting corrosion of titanium and of its alloys in an acid and neutral halogenous environment [fr

  13. ELECTROCHEMICAL BEHAVIOUR AND VOLTAMMETRIC ...

    African Journals Online (AJOL)

    The electrochemical behaviour of Geshoidin was investigated at a glassy carbon electrode in mixtures of citric acid and di-sodium hydrogen orthophosphate aqueous buffer system over a wide pH range (pH 2-11) using cyclic voltammetry. Chemically irreversible single oxidation and reduction peaks were obtained in the ...

  14. Electrochemical Behaviour of Environmentally Friendly Inhibitor of ...

    African Journals Online (AJOL)

    Electrochemical Behaviour of Environmentally Friendly Inhibitor of Aloe Secundiflora Extract in Corrosion Control of Carbon Steel in Soft Water Media. ... The investigation was performed at different inhibitor concentrations under static and dynamic conditions using a Rotating Disk Electrode (RDE). The impedance and ...

  15. Electrochemical tests for pitting and crevice corrosion susceptibility

    International Nuclear Information System (INIS)

    Postlethwaite, J.

    1983-01-01

    Passive metals are being considered as container materials for the disposal of nuclear waste by deep burial. Localized corrosion is a potential problem and electrochemical techniques have an important role in the assessment of the susceptibility of these container materials to crevice and pitting corrosion. This paper critically reviews both the theoretical background and the experimental details of the electrochemical test methods presently used in both industrial and scientific studies of localized corrosion in both halide and non-halide solutions and identifies those areas where theory and experimental behaviour are in agreement and those areas for which there is neither well established theory nor an experimental test method

  16. Contribution to the electrochemical study of corrosion in low-conductivity environments. Application to the study of the behaviour of austenitic stainless steels in concentrated solutions of acetic acid

    International Nuclear Information System (INIS)

    Chechirlian, Serge

    1989-01-01

    As the use of conventional electrochemical methods to study metal and alloy corrosion in concentrated solutions of acetic acid is challenged by difficulties due the low conductivity of these environments, the first part of this research thesis proposes a critical, theoretical and experimental study of these difficulties. It notably evokes the use of electrochemical impedance techniques, the different compensation devices and means of correction of the ohmic voltage drop, and artefacts used during high frequency impedance measurements in lesser conductive solutions. The second part addresses the characterization of the corrosion behaviour of austenitic stainless steels in a concentrated acetic acid at 25 and 95 degrees C. Electrochemical techniques are coupled with analytical methods (solution analysis, sample surface analysis after corrosion tests). The roles of molybdenum as alloying element, of dissolved oxygen, of impurities (sulfites) or of formic acid additions are studied and discussed [fr

  17. Corrosion behaviour of high copper dental amalgams.

    Science.gov (United States)

    Yap, A U J; Ng, B L; Blackwood, D J

    2004-06-01

    This study evaluated the corrosion behaviour of two high copper dental amalgam alloys [Dispersalloy (Dentsply-Caulk) and Tytin (Kerr)] in different electrolytes. Amalgam specimens were prepared, coupled to a copper wire, cemented into glass tubes and polished to a 600-grit finish. A corrosion cell was prepared using a carbon counter-electrode, a standard calomel electrode as the reference and amalgam as the working electrode. The alloys were tested in the following mediums at 37 degrees C: (i) artificial saliva based on Fusayama's solution (FS), (ii) artificial saliva with citric acid adjusted to pH 4.0 (FC) and (iii) 1% sodium chloride solution (SC). Corrosion potentials (E(corr)) and corrosion rates (I(corr)) were determined using potentiostatic and impedance spectroscopy methods. Data was subjected to anova/Scheffe's post hoc test at 0.05 significance level. For both alloys, the corrosion potential in FS was significantly greater than in SC. Corrosion potential of Tytin in FS and SC was also significantly greater than in FC. The corrosion rate of Dispersalloy in FC was significantly greater than in FS and SC. For Tytin, corrosion rate in SC was significantly greater than in FS and FC. Although no significant difference in corrosion potential/rate was observed between the alloys when tested in FS, significant differences were observed when electrochemical testing was carried out in FC and SC. The corrosion behaviour of high copper amalgam alloys are both material and environment dependent. Certain food substances may increase the corrosion of high copper amalgams.

  18. The electrochemical synthesis and corrosion behaviour of TiO2/poly(indole-co-aniline multilayer coating: Experimental and theoretical approach

    Directory of Open Access Journals (Sweden)

    Serap Toprak Döşlü

    2018-01-01

    Full Text Available The aim of this study was to protect stainless steel against corrosion via poly (indole-co-aniline with the help of titanium dioxide pre-coating. Different monomer ratios (1:1 and 1:9 were applied in order to determine the suitable chain composition to synthesize the copolymer in lithium perchlorate containing acetonitrile. The structures, morphologies, electrochemical properties and corrosion resistances of the mono and multi-layer coatings were investigated by Fourier-transform infrared spectra, scanning electron microscope, energy dispersive X-ray spectrometer, electrochemical impedance spectroscopy and anodic polarization. Furthermore the geometric structure and electronic properties of indole, aniline, and indole-co-aniline (dimmer molecules have been investigated by quantum calculations. The results indicated that corrosion protection of copolymers was increased via titanium dioxide pre-coating. The 1:1 copolymer coating showed better corrosion prevention than 1:9 coating. The correlation was determined between experimental and theoretical parameters.

  19. A Course in Electrochemical and Corrosion Engineering.

    Science.gov (United States)

    Van Zee, John

    1985-01-01

    Describes a course designed to show similarities between electrochemistry and corrosion engineering and to show graduate students that electrochemical and corrosion engineering can be accomplished by extending their knowledge of chemical engineering models. Includes course outline, textbooks selected, and teaching methods used. (JN)

  20. Electrochemical and chemical corrosion of chromium

    International Nuclear Information System (INIS)

    Drazic, Dragutin M.; Popic, Jovan P.

    2004-01-01

    It was shown that chromium in deaerated sulfuric acid of pH 1 exhibits two stable corrosion potentials, depending whether the metal had previously been in contact with air or subjected to activation by cathodic evolving hydrogen. Electrochemical polarization measurements, as well as the measurements of the actual metal dissolution rate at the corrosion potential, anodic or cathodic polarization, using the analytical determination of Cr ions in the solution, or volumes of hydrogen evolved, showed that hydrogen can evolve on chromium by three different reaction mechanisms. The first one is the electrochemical hydrogen evolution reaction from H + ions at the bare chromium surface obtained by cathodic activation. This reaction and the active anodic dissolution of chromium determine one stable corrosion potential. The second reaction is the reaction of H + ions on the oxidized chromium surface which, coupled with the anodic dissolution of passivated chromium determines the other stable corrosion potential. The third one is the 'anomalous' or chemical reaction of chromium with water molecules and hydrogen ions whereby hydrogen is liberated. This is a potential independent reaction, occurring on the bare metal surface, and which is at pH 1 several times faster at the corrosion potential than the electrochemical hydrogen evolution reaction. The consequence is that the overall corrosion rate is several times faster than that determined by the usual electrochemical methods. The measurements were performed in the temperature interval 20 - 65 o C and apparent energies of activation for anodic, cathodic and anomalous dissolution reactions were estimated as 63.1, 19.5 and 66.9 kJ mol -1 , respectively. This implies that the anomalous dissolution rate increases more with the increase of temperature than the electrochemical corrosion rate. The applicability of the different methods of measuring electrochemical corrosion rates is discussed. (Author)

  1. Detection of microbiologically influenced corrosion by electrochemical noise transients

    NARCIS (Netherlands)

    Homborg, A.M.; Morales, C.F. Leon; Tinga, Tiedo; de Wit, J.H.W.; Mol, J.M.C.

    2014-01-01

    This work investigates the electrochemical processes involved in pitting corrosion induced by microbiologically influenced corrosion by using time-resolved instantaneous frequency information of electrochemical current noise (ECN) transients obtained from Hilbert spectra. In addition to the

  2. Electrochemical corrosion testing of metal waste forms

    International Nuclear Information System (INIS)

    Abraham, D. P.; Peterson, J. J.; Katyal, H. K.; Keiser, D. D.; Hilton, B. A.

    1999-01-01

    Electrochemical corrosion tests have been conducted on simulated stainless steel-zirconium (SS-Zr) metal waste form (MWF) samples. The uniform aqueous corrosion behavior of the samples in various test solutions was measured by the polarization resistance technique. The data show that the MWF corrosion rates are very low in groundwaters representative of the proposed Yucca Mountain repository. Galvanic corrosion measurements were also conducted on MWF samples that were coupled to an alloy that has been proposed for the inner lining of the high-level nuclear waste container. The experiments show that the steady-state galvanic corrosion currents are small. Galvanic corrosion will, hence, not be an important mechanism of radionuclide release from the MWF alloys

  3. Electrochemical Estimation of the Corrosion Rate of Magnesium/Aluminium Alloys

    Directory of Open Access Journals (Sweden)

    A. Pardo

    2010-01-01

    Full Text Available The corrosion rate of AZ31, AZ80, and AZ91D magnesium/aluminium alloys immersed in 3.5 wt.% NaCl was determined comparing gravimetric and electrochemical measurements. The findings revealed that, for all investigated materials, a fraction of the metallic surface exposed to the corrosive medium did not reveal a normal electrochemical response to the applied signal. This may be associated with phenomena such as partial disintegration of specimens into fine metallic particles, electrochemical formation of Mg+ ions, and/or anomalous chemical attack occurring simultaneously with the normal electrochemical corrosion attack. The abnormal electrochemical behaviour was more evident for lower amounts of aluminium in the bulk composition of the investigated materials. Thus, the electrochemical estimates of pure Mg and the AZ31 alloy were not reliable and tended to underestimate corrosion losses.

  4. Effect of anodization on corrosion behaviour and biocompatibility of ...

    Indian Academy of Sciences (India)

    Pores of some anodized samples are sealed by exposing the anodized surface in boiling water. Corrosion behaviour of the anodized specimen is studied in Ringer's solution at 30 ± 2 °C, using electrochemical impedance and cyclic polarization technique. Biocompatibility of the anodized surface is accessed using MG63 ...

  5. Pitting Corrosion Behaviour of New Corrosion-Resistant Reinforcement Bars in Chloride-Containing Concrete Pore Solution

    OpenAIRE

    Jiang, Jin-yang; Liu, Yao; Chu, Hong-yan; Wang, Danqian; Ma, Han; Sun, Wei

    2017-01-01

    In this study, the pitting behaviour of a new corrosion-resistant alloy steel (CR) is compared to that of low-carbon steel (LC) in a simulated concrete pore solution with a chloride concentration of 5 mol/L. The electrochemical behaviour of the bars was characterised using linear polarisation resistance (LPR) and electrochemical impedance spectroscopy (EIS). The pitting profiles were detected by reflective digital holographic microscopy (DHM), scanning electron microscopy (SEM), and the chemi...

  6. Novel corrosion experiments using the wire beam electrode: (II) Monitoring the effects of ions transportation on electrochemical corrosion processes

    International Nuclear Information System (INIS)

    Aung, Naing Naing; Tan, Yong-Jun; Liu, Tie

    2006-01-01

    An electrochemically integrated multi-electrode system namely the wire beam electrode (WBE) has been applied for the first time to study the effects of the transportation of electrochemically active species on the process, rate and pattern of electrochemical corrosion. The objective of this work is to demonstrate the applicability of the WBE method for investigating ion transportation related corrosion processes. A series of experiments have been carried out using WBEs made from mild steel and stainless steel wires. The WBE working surfaces were exposed to simulated diffusion-controlled corrosion environments where there were diffusion induced ions concentration gradients (termed diffusion-corrosion environment). Corrosion potential and current distribution maps (CPCD maps) were measured from WBE surfaces in continuous bases. Typical patterns have been identified from CPCD maps and the characteristics of these patterns have been found to depend heavily upon the type of electrode material and the type of corrosive ion. For mild steel WBE surface exposed to a diffusion-corrosion environment containing NiSO 4 or FeCl 3 , the characteristic pattern in CPCD maps was found to emulate NiSO 4 or FeCl 3 concentration gradients, suggesting an ion-concentration controlled corrosion behaviour. However, when the mild steel WBE surface was exposed to a diffusion-corrosion environment containing NaCl, the characteristic pattern was found to show higher cathodic currents along the WBE edges with the magnitude decreasing in a contour-like manner towards the centre of the WBE surface, suggesting an oxygen concentration-controlled corrosion behaviour. When a stainless steel (SS316L) WBE surface was exposed to a diffusion-corrosion environment containing NiSO 4 or NaCl, the corrosion pattern appeared to be mainly determined by the random distribution of weak sites in passive film. When the SS316L WBE was exposed to a diffusion-corrosion environment containing FeCl 3 , the CPCD map

  7. Study of corrosion-erosion behaviour of stainless alloys in industrial phosphoric acid medium

    International Nuclear Information System (INIS)

    Guenbour, Abdellah; Hajji, Mohamed-Adil; Jallouli, El Miloudi; Bachir, Ali Ben

    2006-01-01

    The corrosion and corrosion-abrasion resistance of some stainless steels in industrial phosphoric acid 30% P 2 O 5 has been studied using electrochemical techniques. The corrosion rate of materials increases with the increase of temperature. Alloys which contain chromium, molybdenum and nitrogen in sufficient quantities present the best behaviour. In the abrasion-corrosion conditions, the experimental device set up allowed to follow continually samples electrochemical behaviour. Under dynamic conditions and without solid particles, the increase of acid projection speed has no effect on the alloys corrosion behaviour. The adding of abrasive leads to a general increase of corrosion rate and to a decrease of material resistance. Under these conditions, materials attack is controlled by synergistic effect between the abrasion and the impurities. The cast 30% Cr shows good resistance according to his high chromium content

  8. Investigation on the Recent Research Trend in the Corrosion Behaviour of Stainless Steel Weldment

    International Nuclear Information System (INIS)

    Kim, Hwan Tae; Kil, Sang Cheol; Hwang, Woon Suk

    2011-01-01

    The research trend in the corrosion behaviour of stainless steel weldment has been reviewed. The welding technology plays an important role in the fabrication of structure such as chemical plant, power plant, because welding can influence various factors in the performance of plant and equipment. This has led to an increasing attention towards the corrosion behaviour of weldment which has been one of the major issues for both welding and corrosion research engineers. The aim of this paper is to give a short survey of the recent technical trends of welding and corrosion including the electrochemical corrosion, stress corrosion cracking, and corrosion fatigue in connection with the welding materials, welding process, and welding fabrication. This study covers the corrosion behaviour of stainless steel weldment collected from the COMPENDEX DB analysis of published papers, research subject and research institutes

  9. Electrochemical studies on spent fuel corrosion processes

    International Nuclear Information System (INIS)

    Pablo, J. de; Casas, I.; Clarens, F.; Gimenez, J.; Rovira, M.

    2003-01-01

    This presentations is mainly based on the electrochemical studies carried out by the Canadian team and the research group of the Berlin University. Electrochemical studies allow to study separately both the anodic reaction which corresponds-sources on UO 2 -electrodes response is one of to the UO 2 dissolution and the cathodic reaction that is the reduction of the oxidants. By using intensity current-potential plots a mechanisms of UO 2 corrosion has been established. At-300 mV (vs SCE), irreversible oxidation of UO 2 takes place and dissolution begins. In the absence of complexing agents like carbonate, an oxidised layer is formed at 100 mV a stoichiometry close to UO 2 . In carbonate medium, the oxidized layer is not formed because the U(VI) formed is rapidly dissolved. Results in terms of dissolution rates obtained by electrochemical measurements are similar to the ones obtained in dissolution experiments by using flow through reactors and similar kinetic laws are obtained. The effect of external α and γ-sources on UO 2 -electrodes response is one of the few available data on the effects of radiolysis on the UO 2 dissolution rate and can offer a complementary knowledge to the spent fuel and α-doped pellets dissolution experiments. (Author)

  10. Electrochemical impedance study on the corrosion of Al-Pure in ...

    Indian Academy of Sciences (India)

    Abstract. The inhibition effect of newly synthesized Schiff bases N-benzylidene benzylamine (A) and benzenemethanamine-α-methyl-N-(phenylmethylene) (B) on the corrosion behaviour of Al-Pure in 1·0 M HCl was studied using galvanostatic polarization and electrochemical impedance spectroscopy (EIS) and adsorption ...

  11. Corrosion behaviour of layers obtained by nitrogen implantation into boron films deposited onto iron substrates

    International Nuclear Information System (INIS)

    Marchetti, F.; Fedrizzi, L.; Giacomozzi, F.; Guzman, L.; Borgese, A.

    1985-01-01

    The electrochemical behaviour and corrosion resistance of boron films deposited onto Armco iron after bombardment with 100 keV N + ions were determined in various test solutions. The changes in the electrochemical parameters give evidence of lower anodic dissolution rates for the treated samples. Scanning electron microscopy and Auger analysis of the corroded surfaces confirm the presence of protective layers. (Auth.)

  12. Electrochemical Study of Welded AISI 304 and 904L Stainless Steel in Seawater in View of Corrosion

    Directory of Open Access Journals (Sweden)

    Richárd Székely

    2010-10-01

    Full Text Available This is a comparative study of the corrosion behaviour of welds in AISI 304 and AISI 904L stainless steels carried out in seawater model solution in the temperature range 5-35°C and the standard of corrosion testing of welds was followed. The corrosion rate and corrosion attack characteristics were determined for welds of the examined steels with several type of treatment. The aim of this work was to compare the steels based on their resistance against the corrosion in terms of pitting potential (Epit and repassivation potential (Erepass. Seawater is an electrochemically aggressive medium, which can initiate localised corrosion in welded stainless steels. Different electrochemical and testing methods were used, including cyclic voltammetry, chronopotentiometry, electrochemical impedance spectroscopy (EIS, pH measuring and penetration tests.

  13. Corrosion-electrochemical behavior of metals in alkali solutions

    International Nuclear Information System (INIS)

    Levin, V.A.; Levina, E.Eh.

    1995-01-01

    Results of an investigation into corrosion-electrochemical behaviour of 12Kh18N10T, 10Kh17N13M2T, 08Kh21N6M2T and 15Kh25T steels, 06KhN28MDT and KhN78T alloys as well as NP-2 nickel in sodium, potassium and lithium hydroxide solutions at 95-180 deg C temperatures are considered. It is ascertained, that anode polarization curves of all metals irrespective of hydroxide nature, concentration, temperature, presence of chloride and chlorate additions, are of identic character. The movement of anode polarization curves in the direction of lower current of hydroxide type in NaOH-KOH-LiOH series, temperature and solution concentration reduction at other equal terms. 12 refs.; 6 figs

  14. Electrochemical corrosion of cermet coatings in artificial marine water

    International Nuclear Information System (INIS)

    Cabot, P.L.; Fernandez, J.; Guilemany, J.M.

    1998-01-01

    The electrochemical corrosion of different WC+12Co coatings sprayed on 34CrMo4 (UNS-G41350) steel by the high velocity oxygen fuel technique has been studied by corrosion potential and impedance measurements considering previous SEM observations and EDX microanalysis. The experiments were conducted in artificial marine water at 20 C and the impedance spectra were obtained at the corresponding corrosion potentials for the substrate, coating and substrate-coating systems. The impedance diagrams indicated that the electrochemical corrosion of the steel-coating systems is controlled by oxygen diffusion through a porous film of corrosion products, as in the case of the shot-blasted steel. In contrast, the corrosion of the coating appeared to be controlled by diffusion of oxygen through the electrolyte. The impedance diagrams obtained for the steel-coating systems depended on the porosities of the cermet coatings, thus being an useful procedure to characterize metals coated by cermets. (orig.)

  15. Novel corrosion experiments using the wire beam electrode: (III) Measuring electrochemical corrosion parameters from both the metallic and electrolytic phases

    International Nuclear Information System (INIS)

    Tan, Yong-Jun; Liu, Tie; Aung, Naing Naing

    2006-01-01

    The wire beam electrode (WBE) and the scanning reference electrode technique (SRET) have been applied in a novel combination to measure, for the first time, electrochemical parameters simultaneously from both the metallic and electrolytic phases of a corroding metal surface. The objective of this work is to demonstrate the application of this combined WBE-SRET method in obtaining unique information on localised corrosion mechanism, by investigating typical corrosion processes occurring over a mild steel WBE surface exposed to the classic Evans solution. The WBE method was used to map current and potential distributions in the metallic phase, and the SRET was used to map current or potential distribution in the electrolytic phase. It has been found that the combined WBE-SRET method is able to gain useful information on macro-cell electrochemical corrosion processes that involve macro-scale separation of anodes and cathodes. In such macro-cell corrosion systems, maps measured using WBE and SRET were found to correlate with each other and both methods were able to detect the locations of anodic sites. However the movement of the scanning probe during SRET measurements was found to affect the SRET detection of cathodic sites. In micro-cell corrosion systems where the separation of anodic and cathodic sites were less distinct, SRET measurement was found to be insensitive in detecting anodic and cathodic sites, while the WBE method was still able to produce results that correlated well with observed corrosion behaviour. Results obtained from this work suggest that the WBE-SRET method is applicable for understanding the initiation, propagation and electrochemical behaviour of localised corrosion anodes and cathodes, and also their dependence on externally controllable variables, such as solution pH changes and the existence of surface coatings

  16. Electrochemical study of corrosion inhibition of stainless steel in phosphoric medium

    Energy Technology Data Exchange (ETDEWEB)

    Hnini, K.; Chtaini, A. [Laboratoire d' Electrochimie et de Bio Corrosion, Faculte des Sciences et Techniques, Beni-Mellal (Morocco); Khouili, M.; Elbouadili, A. [Laboratoire de Chimie Organique et Analytique, Faculte des Sciences et Techniques, Beni-Mellal (Morocco)

    2004-07-01

    The corrosion of metals represents a terrible waste of both natural resources and money, the failure of some stainless steel resulting from pitting corrosion is some times considered a technological problem, consequently, much effort has been expended in attempting to understand and overcome the corrosion therefore, many stainless steel/ environment combinations have been studied. The use of heterocyclic compounds as inhibitors is one of the most practical methods for protection against corrosion in acidic media. In continuation of our work on development of macrocyclic compounds as corrosion inhibitors we report in our study the corrosion inhibiting behaviour of organic compound Methoxy-2-Allyl-4 Phenol (MAP) containing coordinating and conjugation groups, at three forms (natural, polymerized and chemically treated) on the corrosion of stainless steel in phosphoric acid. This study focused on the comparison for corrosion inhibition proprieties of these different applications using potentiodynamic polarization, electrochemical impedance spectroscopy and SEM. The specimen was evaluated to determine change in his corrosion potential and resistance polarization; These MAP products have exhibited corrosion inhibition by maintaining a high resistance polarization (low corrosion rate) in each application. These results reveal that this compound is efficient inhibitor in all forms; the most inhibition efficiency is obtained with polymerized form. To further evaluate the test data, the steel surfaces were analyzed using scanning electron microscopy, SEM observations of surface treated concrete confirmed presence of inhibitor on the steel surfaces. (authors)

  17. Electrochemical behaviour of superhydrophobic coating fabricated ...

    Indian Academy of Sciences (India)

    surface caused by the presence of CNTs. The electrochemical observations indicate the presence of a positive shift of Ecorr that confers a better corrosion resistance of the coated samples. Keywords. Al alloy; surface coating; superhydrophobicity; potentiodynamic polarization. 1. Introduction. Aluminium and its alloys exhibit ...

  18. Electrochemical behaviour of alkaline copper complexes

    Indian Academy of Sciences (India)

    cyanide- plating bath for copper has been developed using alkaline trisodium citrate and triethanolamine solutions5. The present investigation presents cyclic voltammetric studies on the electrochemical behaviour of alkaline copper complexes, ...

  19. Electrochemical assessment of magnetite anti corrosive paints

    International Nuclear Information System (INIS)

    Escobar, D. M.; Arroyave, C.; Jaramillo, F.; Mattos, O. R.; Margarit, I. c.; Calderon, J.

    2003-01-01

    With the purpose of deepening in the understanding of the mechanisms of protection of anticorrosive pigments based on iron oxides, this work has been carried out on the production of pure magnetite, and copper and chromium doped magnetite, which were evaluated by different characterization techniques. The paints were prepared with a solvent less epoxy resin maintaining the Pigment volume Content near the Practical Critical value (CPVC), established for each pigment. The paints were applied on polished steel and monitored with electrochemical techniques at total immersion conditions. Permeability and impedance measurements of free films were also done. Impedance data were simulated with the Boukamp software. Results show that the paints pigmented with doped magnetite present better behaviour than a paint prepared with commercial hematite. (Author) 8 refs

  20. Electrochemical Corrosion Investigations on Anaerobic Treated Distillery Effluent

    Science.gov (United States)

    Ram, Chhotu; Sharma, Chhaya; Singh, A. K.

    2014-09-01

    Present study is focused on the corrosivity of anaerobic treated distillery effluent and corrosion performance of mild steel and stainless steels. Accordingly, electrochemical polarization tests were performed in both treated distillery and synthetic effluents. Polarization tests were also performed in synthetic solutions and it was observed that Cl- and K+ increase whereas SO4 -, PO4 -, NO3 -, and NO2 - decrease the corrosivity of effluent at alkaline pH. Further, comparison in corrosivity of distillery and synthetic effluents shows the former to be less corrosive and this is assigned due to the presence of amino acids and melanoidins. Mild steel experienced to have the highest corrosion rate followed by stainless steels—304L and 316L and lowest in case of SAF 2205. Relative corrosion resistance of stainless steels is observed to depend upon Cr, Mo, and N content.

  1. Corrosion behaviour of AISI 304 stainless steel subjected to massive laser shock peening impacts with different pulse energies

    International Nuclear Information System (INIS)

    Lu, J.Z.; Qi, H.; Luo, K.Y.; Luo, M.; Cheng, X.N.

    2014-01-01

    Highlights: •Laser shock peening caused an obvious increase of corrosion resistance of 304 steel. •Corrosion resistance of stainless steel increased with increasing pulse energy. •Mechanism of laser shock peening on corrosion behaviour was also entirely determined. -- Abstract: Effects of massive laser shock peening (LSP) impacts with different pulse energies on ultimate tensile strength (UTS), stress corrosion cracking (SCC) susceptibility, fracture appearance and electrochemical corrosion resistance of AISI 304 stainless steel were investigated by slow strain rate test, potentiodynamic polarisation test and scanning electron microscope observation. The influence mechanism of massive LSP impacts with different pulse energies on corrosion behaviour was also determined. Results showed that massive LSP impacts effectively caused a significant improvement on UTS, SCC resistance, and electrochemical corrosion resistance of AISI 304 stainless steel. Increased pulse energy can also gradually improve its corrosion resistance

  2. Corrosion behaviour of laser-cleaned AA7024 aluminium alloy

    Science.gov (United States)

    Zhang, F. D.; Liu, H.; Suebka, C.; Liu, Y. X.; Liu, Z.; Guo, W.; Cheng, Y. M.; Zhang, S. L.; Li, L.

    2018-03-01

    Laser cleaning has been considered as a promising technique for the preparation of aluminium alloy surfaces prior to joining and welding and has been practically used in the automotive industry. The process is based on laser ablation to remove surface contaminations and aluminium oxides. However the change of surface chemistry and oxide status may affect corrosion behaviour of aluminium alloys. Until now, no work has been reported on the corrosion characteristics of laser cleaned metallic surfaces. In this study, we investigated the corrosion behaviour of laser-cleaned AA7024-T4 aluminium alloy using potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). The results showed that the laser-cleaned surface exhibited higher corrosion resistance in 3.5 wt.% NaCl solution than as-received hot-rolled alloy, with significant increase in impedance and decrease in capacitance, while SVET revealed that the active anodic points appeared on the as-received surface were not presented on the laser-cleaned surfaces. Such corrosion behaviours were correlated to the change of surface oxide status measured by glow discharge optical emission spectrometry (GDOES) and X-ray photoelectron spectroscopy (XPS). It was suggested that the removal of the original less protective oxide layer consisting of MgO and MgAl2O4 on the as-received surfaces and the newly formed more protective oxide layer containing mainly Al2O3 and MgO by laser cleaning were responsible for the improvement of the corrosion performance.

  3. Electrochemical noise based corrosion monitoring: FY 2001 final report

    International Nuclear Information System (INIS)

    EDGAR, C.

    2001-01-01

    Underground storage tanks made of mild steel are used to contain radioactive waste generated by plutonium production at the Hanford Site. Corrosion of the walls of these tanks is a major issue. Corrosion monitoring and control are currently provided at the Hanford Site through a waste chemistry sampling and analysis program. In this process, tank waste is sampled, analyzed and compared to a selection of laboratory exposures of coupons in simulated waste. Tank wall corrosion is inferred by matching measured tank chemistries to the results of the laboratory simulant testing. This method is expensive, time consuming, and does not yield real-time data. Corrosion can be monitored through coupon exposure studies and a variety of electrochemical techniques. A small number of these techniques have been tried at Hanford and elsewhere within the DOE complex to determine the corrosivity of nuclear waste stored in underground tanks [1]. Coupon exposure programs, linear polarization resistance (LPR), and electrical resistance techniques have all been tried with limited degrees of success. These techniques are most effective for monitoring uniform corrosion, but are not well suited for early detection of localized forms of corrosion such as pitting and stress corrosion cracking (SCC). Pitting and SCC have been identified as the most likely modes of corrosion failure for Hanford Double Shell Tanks (DST'S) [2-3]. Over the last 20 years, a new corrosion monitoring system has shown promise in detecting localized corrosion and measuring uniform corrosion rates in process industries [4-20]. The system measures electrochemical noise (EN) generated by corrosion. The term EN is used to describe low frequency fluctuations in current and voltage associated with corrosion. In their most basic form, EN-based corrosion monitoring systems monitor and record fluctuations in current and voltage over time from electrodes immersed in an environment of interest. Laboratory studies and field

  4. Corrosion and wear resistant metallic layers produced by electrochemical methods

    DEFF Research Database (Denmark)

    Christoffersen, Lasse; Maahn, Ernst Emanuel

    1999-01-01

    Corrosion and wear-corrosion properties of novel nickel alloy coatings with promising production characteristics have been compared with conventional bulk materials and hard platings. Corrosion properties in neutral and acidic environments have been investigated with electrochemical methods....... Determination of polarisation resistance during 100 hours followed by stepwise anodic polarisation seems to be a promising technique to obtain steady state data on slowly corroding coatings with transient kinetics. A slurry test enables determination of simultaneous corrosion and abrasive wear. Comparison...... of AISI 316, hard chromium and hardened Ni-P shows that there is no universal correlation between surface hardness and wear-corrosion loss. The possible relation between questionable passivity of Ni-P coatings and their high wear-corrosion loss rate compared to hard chromium is discussed....

  5. Corrosion rate evaluation of the carbon steel trough electrochemical techniques

    Directory of Open Access Journals (Sweden)

    Jeimmy González-Masís

    2014-02-01

    Full Text Available Usually the atmospheric corrosion studies are cha­racterized by their long duration, months and even years. However electrochemical techniques have been developed, recent in comparison to other methods, allowing obtain real-time data, including corrosion rate. In this research electrochemical noise and lineal polarization resistance tests are valued, so obtained data were analyzed, relations were establis­hed between the graphics form and the corrosion type, as well as the relationship between the corro­sion data and atmospheric conditions, to find, finally, there is a more consistent behavior when the lineal polarization resistance test is used with the three comb-type electrodes electrochemical monitor.

  6. Electrochemical evaluation of crevice corrosion in stainless steels

    International Nuclear Information System (INIS)

    Flyg, J.; Jargelius-Pettersson, R.F.A.

    1998-01-01

    An electrochemical method for the evaluation of crevice corrosion in stainless steels is described. Specimens are carefully abraded in order to give a large number of microcrevices when the specimen is placed in contact with a rubber o-ring. Twelve specimens are tested simultaneously in a purpose-built electrochemical cell. A constant potential is applied to the specimens and the temperature automatically raised at intervals until a current increase indicates the onset of crevice corrosion and thereby defines the critical crevice corrosion temperature (CCT). Testing has been performed on a wide range of stainless steels in 3.5% NaCl at +700 mV SCE. The temperature was raised by 5 C every 70 minutes. Results show good reproducibility with a typical standard deviation of below 5 C. There is also excellent agreement with the ranking of crevice corrosion resistance for different steel grades which is obtained by immersion testing in 6% FeCl 3 solution. (orig.)

  7. Corrosion, haemocompatibility and bacterial adhesion behaviour of ...

    Indian Academy of Sciences (India)

    Bacterial adhesion, haemocompatibility and corrosion behaviour of TiZrN coating were examined in order to evaluate the coating's compatibility for ideal implant. Results revealed that TiZrN coatings exhibited less bacterial attachment against Staphylococcus aureus and Escherichia coli bacteria, negligible platelets ...

  8. Corrosion, haemocompatibility and bacterial adhesion behaviour of ...

    Indian Academy of Sciences (India)

    TiZrN coating was deposited on 316L stainless steel (SS) by the reactive magnetron co-sputtering technique. Cubic phase of TiZrN with uniform surface morphology was observed by X-ray diffraction and atomic force microscopy. Bacterial adhesion, haemocompatibility and corrosion behaviour of TiZrN coating were ...

  9. Electrochemical corrosion measurements on noble electrodeposits

    DEFF Research Database (Denmark)

    Christoffersen, Lasse; Maahn, Ernst Emanuel

    1998-01-01

    Novel electrodeposits are compared with hard chrome and electroless Ni-P with respect to production, corrosion resistance and hardness.......Novel electrodeposits are compared with hard chrome and electroless Ni-P with respect to production, corrosion resistance and hardness....

  10. Electrochemical study of stress corrosion cracking of copper alloys

    International Nuclear Information System (INIS)

    Malki, Brahim

    1999-01-01

    This work deals with the electrochemical study of stress corrosion of copper alloys in aqueous environment. Selective dissolution and electrochemical oxidation are two key-points of the stress corrosion of these alloys. The first part of this thesis treats of these aspects applied to Cu-Au alloys. Measurements have been performed using classical electrochemical techniques (in potentio-dynamic, potentio-static and galvano-static modes). The conditions of occurrence of an electrochemical noise is analysed using signal processing techniques. The impact on the behavior of Cu 3 Au are discussed. In the second part, the stress corrosion problem is addressed in the case of surface oxide film formation, in particular for Cu-Zn alloys. We have found useful to extend this study to mechanical stress oxidation mechanisms in the presence of an oscillating potential electrochemical system. The aim is to examine the influence of these new electrochemical conditions (galvano-static mode) on the behavior of stressed brass. Finally, the potential distribution at crack tip is calculated in order to compare the different observations [fr

  11. Electrochemical corrosion characteristics of aluminium alloy 6061 T6 in demineralized water containing 0.1 % chloride ion

    International Nuclear Information System (INIS)

    Zaifol Samsu; Muhammad Daud; Siti Radiah Mohd Kamarudin; Mohd Saari Ripin; Rusni Rejab; Mohd Shariff Sattar

    2012-01-01

    Direct current electrochemical method is one of the techniques has been used to study the corrosion behaviour of metal/alloy in its environment. This paper attempts to investigate the corrosion behaviour of Al 6061 T6 immersed in Reactor TRIGA Mark II pool water containing about 0.1% NaCl content. The result shown that the corrosion rate value of the aluminium 6061 T6 increased with the presence of 0.1 % Ion Chloride content in the demineralized water reactor pool as compared to normal demineralized water. This is due to aggressiveness of chloride ion attack to metal surface. Beside corrosion rate analysis, the further tests such as corrosion behaviour diagram, cyclic polarization have been carried and the results have been reported. (author)

  12. Evaluation of corrosion resistance of two engineering alloys in molten salts by electrochemical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Villafane, A.; Almeraya-Calderon, F.; Gaona-Tiburcio, C.; Chacon-Nava, J. [Centro de Investigacion en Materiales Avanzados, S.C., Division de Deterioro de Materiales e Integridad Estructural, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico); Gonzalez-Rodriguez, G. [Universidad Autonoma del Estado de Morelos, Fac. Ciencias Qu' micas e Industriales, Av. Universidad No. 1001, Col. Chamilpa, C.P. 62215, Cuernavaca, Morelos (Mexico)

    2003-01-01

    The electrochemical behaviour of two steels typically used in power boilers has been studied in the temperature range from 540 C to 680 C. Two environments were used: a) a synthetic salt mixture of 80% V{sub 2}O{sub 5}-20% Na{sub 2}SO{sub 4} and b) oil ash collected from a high temperature reheater. Corrosion rates obtained from electrochemical potentiodynamic polarisation curves (Tafel extrapolation) were compared for both steels exposed in each environment. The results showed that increases in temperature resulted in higher corrosion rates, being this effect most notorious above about 620 C. In the synthetic salt, and at temperatures up to about 580 C, both steels showed similar behaviour. With further increases in temperature, the T22 steel was less resistant and, at the highest temperature used here, its corrosion rate was almost seven times higher than that measured for the 347H steel. The results obtained with the natural oil ash for the T22 steel showed a dramatic increase in corrosion rate as temperature goes up over the range used. For the 347H steel, and up to about 580 C, the corrosion rates were similar to those obtained with the synthetic salt. Above 580 C, the corrosion rate measured increased slightly with temperature, being at 680 C about 2.5 times higher than that found by using the synthetic salt. Therefore, an important difference in corrosion rates has been found depending upon the corrosive salt used. This is an important result because imply that, at least for materials used in fossil power plants, more realistic data can be obtained by using natural ashes in the experimental work. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  13. Electrochemical study of corrosion layer of archaeological object formed in atmospheric corrosion; Etude electrochimique de couche de corrosion d'objet archeologique formee en corrosion atmospherique

    Energy Technology Data Exchange (ETDEWEB)

    Antony, H.; Perrin, St.; Legrand, L.; Chausse, A. [Univ. d' Evry-val-d' Essonne, Laboratoire Analyse et Modelisation pour la Biologie et l' Environnement (LAMBE CNRS UMR 8587), 91 - Evry (France); Antony, H.; Perrin, St. [CEA Saclay, Dept. de Physico-Chimie (DEN/DPC/SCCME), Lab. d' Etude de la Corrosion Aqueuse, 91 - Gif sur Yvette (France); Monnier, J.; Dillmann, Ph. [Laboratoire Pierre Sue (LPS) CEA/CNRS, (DSM/DRECAM/SCM)- CEA Saclay, 91 - Gif-sur-Yvette (France)

    2007-07-01

    The degradation of iron materials in atmospheric corrosion is a well known phenomenon which can have important consequences, particularly in the case of radioactive wastes storage/disposal. The corrosion layers developed on old patrimony objects are very interesting sources to give data at predictive corrosion models because they allow to report data on several thousands years periods. In this work has been studied the electrochemical behaviour of such layers in reduction. Rust powders have been scraped on old objects (0-800 years). These powders have been mixed with graphite in mass ratio: 20/80, and then compacted on platinum grid to constitute composite electrodes. Chrono-potentiometric answers have been obtained under a current imposition of 25 {mu}A/mg, in NaCl medium 0.1 mol/L{sup -1} at neutralized pH of 7.5 and at 25 C. From these results, two parameters have been determined, Q{sub {tau}} corresponding to the electric power quantity implemented during the reduction process and E{sub {tau}}{sub /2} corresponding to the potential value of half-reaction. These two parameters allow to estimate the 'reactivity in reduction' of the corrosion layer; this reactivity decreases with the age of the object, which could suggest a stabilization of the layer with time. In a second part, the 'reactivity in reduction' has been correlated with the composition of the layer. The electrochemical answers obtained with the old layers have been reproduced in making synthetic powder mixtures of ferritic compounds (goethite, lepidocrocite, ferri-hydrite...). (O.M.)

  14. Electrochemical supercapacitor behaviour of functionalized candle ...

    Indian Academy of Sciences (India)

    2Department of Ceramic Engineering, Gangneung-Wonju National University, Gangneung 210 702, Republic of Korea. MS received 15 March 2015; accepted 17 August 2015. Abstract. The electrochemical supercapacitor behaviour of bare, washed and nitric acid functionalized candle flame carbon soots were reported.

  15. Evaluation of microstructural effects on the corrosion behaviour of AZ91D magnesium alloy

    DEFF Research Database (Denmark)

    Ambat, Rajan; Aung, Naing Naing; Zhou, W.

    2000-01-01

    The effect of microconstituents on the corrosion and electrochemical behaviour of AZ91D alloy prepared by die-casting and ingot casting route has been investigated in 3.5% NaCl solution at pH 7.25. The experimental techniques used include constant immersion technique, in-situ corrosion monitoring...... phase offered marginally lower corrosion rate and better passivation compared with the ingot. In die-cast and ingot, hydrogen evolution took place preferentially on beta phase. XRD pattern of non-corroded and corroded surface revealed the removal of beta phase from alloy surface during corrosion......, and potentiodynamic polarisation experiments. Surface examination and analytical studies were carried out using optical and scanning electron microscopy, EDX and XRD. The corrosion behaviour of microconstituents namely primary alpha, eutectic alpha and beta phases was significantly different. Goring of aluminum...

  16. Effect of Iron-Containing Intermetallic Particles on the Corrosion Behaviour of Aluminium

    DEFF Research Database (Denmark)

    Ambat, Rajan

    2006-01-01

    The effect of heat treatment on the corrosion behaviour of binary Al-Fe alloys containing iron at levels between 0.04 and 0.42 wt.% was investigated by electrochemical measurements in both acidic and alkaline chloride solutions. Comparing solution heat-treated and quenched materials with samples...... with {100} facets, and are observed to contain numerous intermetallic particles. Fine facetted filaments also radiate out from the periphery of pits. The results demonstrate that the corrosion of "pure" 99.96% Al is thus dominated by the role of iron, which is the main impurity, and its electrochemical...

  17. Corrosion and electrochemical properties of lanthanum

    International Nuclear Information System (INIS)

    Tomashov, N.D.; Matveeva, T.V.

    The kinetics of the corrosion rate of lanthanum at 25 0 in air of different relative humidities, distilled water, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, hydrofluoric acid, potassium hydroxide of different concentrations and at 100 0 C in distilled water and potassium hydroxide have been studied. In air at 22--100% relative humidity, the corrosion rate of lanthanum increases with time and with increasing humidity. In distilled water and in potassium hydroxide solutions, the corrosion rate of lanthanum increases with time and decreasees when the concentration of alkali exceeds 20%. With increasing concentration of the acids, the corrosion rate of lanthanum increases in hydrochloric acid and nitric acid and passes through a maximum in sulfuric acid (20%) and phosphoric acid (60%). The values of the corrosion rates of lanthanum in 40% nitric acid, 35% hydrochloric acid, 20% sulfuric acid, 60% phosphoric acid, and 40% hydrofluoric acid are 8 x 10 5 ; 4.4 x 10 4 ; 1.3 x 10 3 ; 9 g/m 2 h respectively

  18. Influence of pH and oxygen content of buffer solutions on the corrosion behaviour of metallic materials

    International Nuclear Information System (INIS)

    Wiedemann, K.H.

    1977-05-01

    The application of solutions to the decontamination of materials in nuclear installations is based on the condition that their corrosion behaviour is clearly understood. Since electrochemical corrosion is due to cathodic and anodic partial reactions which are influenced in different ways by the pH of the solution and the oxygen content it is suggested that the results of electrochemical experiments with buffer solutions be used as a model for predicting the corrosion behaviour of materials in other solutions. In the tests described here potentio-kinetic current-potential-curves have been traced and galvanic corrosion tests have been made. The results obtained in ascorbic acid, potassium hydrogen phthalate, ammonium citrate and acetate, sodium and potassium tartrate, ammonium hydrogen phosphate, sodium carbonate, hexamethylene tetramin, ethylene diamine enable - on the basis of summarized current-potential-curves - the metals studied to be classified in four groups characterized by clear differences concerning the influence of pH on the corrosion behaviour. (Auth.)

  19. An electrochemical study of the effect of nitrate and sulphate on the corrosion behaviour of Magnox AL80 in pond environments

    International Nuclear Information System (INIS)

    Tyfield, S.P.; Martin, F.

    1987-04-01

    The open circuit rest potential and the cyclic potentiodynamic polarisation behaviour of abraded Magnox AL80 has been studied at 22 0 C in sodium hydroxide solutions (200 gm -3 , pH ∼ 11.6) dosed separately and with a combination of chloride and nitrate. The results are considered in terms of the effect of the presence of nitrate on the initiation of localised breakdown of the passive film on Magnox AL80. A similar study of the effect of the presence of sulphate in the sodium hydroxide medium (200 gm -3 ) is described and the aggressivity of sulphate is compared to that of chloride. (author)

  20. Corrosion behaviour of sintered duplex stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Utrilla, M. Victoria; Urena, Alejandro; Otero, Enrique; Munez, Claudio Jose [Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, C/ Tulipan s/n, 28933 Mostoles, Madrid (Spain)

    2004-07-01

    Duplex austenite-ferrite stainless steels were prepared by mixing austenitic (316L) and ferritic (434L) atomized powders. Although different 316L/434L ratios were prepared, present work centred its study on 50% ferrite - 50% austenite sintered steel. The powders were mixed and pressed at 700 MPa and sintered at 1250 deg. C for 30 min in vacuum. The cooling rate was 5 deg. C/min. Solution treatment was carried out to homogenize the microstructure at 1100 deg. C during 20 min. A microstructural study of the material in solution was performed, evaluating the microstructure, proportion and shape of porosity, and ferrite percentage. This last was measured by two methods, quantitative metallography and Fischer ferrito-metry. The materials were heat treated in the range of 700 to 1000 deg. C, for 10, 30 and 60 min and water quenched, to study the microstructural changes and the influence on the intergranular corrosion resistance. The method used to evaluate the sensitization to the intergranular corrosion was the electrochemical potentio-kinetic reactivation procedure (EPR). The test solution was 0.5 M H{sub 2}SO{sub 4} + 0,01 M KSCN at 30 deg. C. The criterion used to evaluate the sensitization was the ratio between the maximum reactivation density (Ir) and the maximum activation density (Ia). The results of the electrochemical tests were discussed in relation with the microstructures observed at the different heat treatments. (authors)

  1. Influence of surface roughness on the corrosion behaviour of magnesium alloy

    International Nuclear Information System (INIS)

    Walter, R.; Kannan, M. Bobby

    2011-01-01

    Research highlights: → Surface roughness of AZ91 magnesium alloy plays a critical role in the passivation behaviour of the alloy. → The passivation behaviour of the alloy influences the pitting tendency. → Increase in surface roughness of AZ91 magnesium alloy increases the pitting tendency of the alloy. -- Abstract: In this study, the influence of surface roughness on the passivation and pitting corrosion behaviour of AZ91 magnesium alloy in chloride-containing environment was examined using electrochemical techniques. Potentiodynamic polarisation and electrochemical impedance spectroscopy tests suggested that the passivation behaviour of the alloy was affected by increasing the surface roughness. Consequently, the corrosion current and the pitting tendency of the alloy also increased with increase in the surface roughness. Scanning electron micrographs of 24 h immersion test samples clearly revealed pitting corrosion in the highest surface roughness (Sa 430) alloy, whereas in the lowest surface roughness (Sa 80) alloy no evidence of pitting corrosion was observed. Interestingly, when the passivity of the alloy was disturbed by galvanostatically holding the sample at anodic current for 1 h, the alloy underwent high pitting corrosion irrespective of their surface roughness. Thus the study suggests that the surface roughness plays a critical role in the passivation behaviour of the alloy and hence the pitting tendency.

  2. Electrochemical Noise : A Clear Corrosion Signature

    NARCIS (Netherlands)

    Homborg, A.M.

    2014-01-01

    The interpretation of electrochemical noise (EN) data has long been under discussion. Throughout the years, many data analysis techniques have been proposed for this purpose. As a starting point, procedures and parameters that enable identification of, or discrimination between, general and

  3. Screening of soil corrosivity by field testing: Results and design of an electrochemical soil corrosion probe

    DEFF Research Database (Denmark)

    Nielsen, Lars vendelbo; Bruun, Niels Kåre

    1996-01-01

    The corrosivity of different types of soil have been assessed by exposing carbon-steel plates at 50 different locations in Denmark for an extended period of time. The investigations included weight loss measurements and analysis of the chemical compositions of the corrosion products formed on the...... and hydrogen absorption rates. In addition, traditional carbon-steel 3-electrode arrangements allow for performance of any kind of electrochemical meaurement (EIS, polarisation curves, LPR-measurements, galvanostatic pulse etc.).......The corrosivity of different types of soil have been assessed by exposing carbon-steel plates at 50 different locations in Denmark for an extended period of time. The investigations included weight loss measurements and analysis of the chemical compositions of the corrosion products formed...... on the plates during exposure. An electrochemical soil corrosion probe has been designed and manufactured allowing for simultaneous measurements of several qauntities to predict corrosion. The probe consists of individual sections capable of measuring redox-potential, corrosion potential, soil resistivity...

  4. Chemical and electrochemical aspects of the corrosion of stainless steels in the presence of sulphate reducing bacteria

    International Nuclear Information System (INIS)

    Feron, D.

    1990-01-01

    The corrosion behaviour of austenitic and ferritic stainless steels (316 L and 430Ti) in the presence of sulfate reducing bacteria, was investigated by several electrochemical techniques which were coupled with corrosion measurements on coupons and chemical analyses. Experiments were performed with 'Desulfovibrio vulgaris' and 'Desulfovibrio gigas' in three growth media containing lactate and sulfate. The decreases in corrosion potentials were correlated to the increase in sulphide content. The polarization curves showed also the major influence of sulphides on the passivity of stainless steels. Electrochemical impedance measurements were used to provide information in understanding the interactions between growth media or bacteria and stainless steels surfaces. The behaviour of the tested stainless steels in these conditions was mainly dependent on sulphide concentrations. (Author). 7 refs., 8 figs., 4 tabs

  5. Investigation of adding fluoroapatite nanoparticles on compressive strength and corrosion behaviour of dental amalgams

    Directory of Open Access Journals (Sweden)

    Fahimeh Mirlohi

    2012-12-01

    Full Text Available In recent years, there have been many efforts to improve biological and biocompatibility features of amalgam. The aim of this research was investigating the effect of adding fluoroapatite (FA nanoparticles on compressive strength and corrosion behaviour of dental amalgam. An amalgam alloy powder was mixed with 1, 3 and 5 wt.% of FA nanoparticles to form composite powders. Compressive strength of the corresponding dental amalgam samples was measured on the first and seventh day after preparation and the corrosion behaviour was investigated by potentiodynamic polarization electrochemical test in 0.9 wt.% salt solution (physiologic serum. The results showed that the amalgam containing 1 wt.% FA nanoparticles has higher compressive strength then the pure amalgam and with increasing the FA content in amalgam to 3 and 5 wt.%, the compressive strength decreases. The results also indicated that the corrosion behaviour of the amalgam sample with 1 wt.% FA is similar to the corrosion behaviour of the original amalgam, while with increasing the weight percentage of fluorapatite, the corrosion resistance decreases. The results of this research showed that adding FA nanoparticles in amounts of up to 1 wt.% to amalgam alloy improve compressive strength, has no destructive effect on corrosion behaviour of the material and can increase its biocompatibility and biological activity.

  6. The crevice corrosion behaviour of stainless steel in sodium chloride solution

    International Nuclear Information System (INIS)

    Hu Qian; Zhang Guoan; Qiu Yubin; Guo Xingpeng

    2011-01-01

    Highlights: → There are three stages in crevice corrosion of 13Cr stainless steel in NaCl solution. → The decrease of crevice thickness shortens the incubation period of crevice corrosion. → The incubation period of crevice corrosion prolongs as the increase of the area ratio. → Corrosion develops preferentially at crevice bottom and hydrogen reduction occurs inside the crevice. → Crevice corrosion of 13Cr stainless steel in NaCl solution follows the passive dissolution mechanism. - Abstract: The crevice corrosion behaviour of 13Cr stainless steel in NaCl solution was investigated mainly by electrochemical noise measurements, considering the influences of the crevice opening dimension (a) and the area ratio of the electrode outside the crevice to the one inside the crevice (r). Results show that the increase of r value prolongs the incubation period of crevice corrosion, but crevice corrosion develops rapidly once the crevice corrosion occurs. The crevice corrosion develops preferentially at the crevice bottom and then spreads to the whole electrode surface. Proton could reduce on the uncorroded area and hydrogen bubbles form inside the crevice.

  7. Study of caffeine as corrosion inhibitors of carbon steel in chloride solution containing hydrogen sulfide using electrochemical impedance spectroscopy (EIS)

    Science.gov (United States)

    Solehudin, Agus; Berman, Ega Taqwali; Nurdin, Isdiriayani

    2015-09-01

    The corrosion behaviour of steel surface in the absence and presence of caffeine in 3.5% NaCl solution containing dissolved H2S gas is studied using electrochemical impedance spectroscopy (EIS). The experimental results of carbon steel corrosion in 3.5% NaCl solution containing 500 mg/l H2S at different caffeine concentrations showed that corrosion rate of carbon steel decreases with increasing of caffeine concentrations from 0 to 0,1 mmol/l. Whereas, the corrosion rate increase with increasing of caffeine concentrations from 1 to 10 mmol/l. It is clear that no inhibition efficiency increases with increasing inhibitor concentration. The optimum value of inhibition efficiency was 90% at a caffeine concentration of 0.1 mmol/l. This suggests that caffeine's performance as a corrosion inhibitor is more effective at a concentration of 0.1 mmol/l.

  8. An electrochemical engineering technique to improve the corrosion resistance of some structural materials in lead-alloy coolants

    International Nuclear Information System (INIS)

    Tacica, M.; Andrei, V.; Rusu, O.; Coaca, E.; Minca, M.; Florea, S.; Oncioiu, G.

    2013-01-01

    The goal of this paper is to present some conclusions resulted from the literature studies referring to the materials potential to be used in Lead Fast Reactors (LFR), and the results obtained in the surface engineering field which can be used in our institute in order to obtain materials with appropriate properties for their use in LFR. In this context, the paper presents some preliminary results obtained in Surface Analysis Laboratory of INR Pitesti and research works in progress referring to: controlled modification of AISI 316 L surface by electrochemical plasma treatment (carburization, nitrocarburizings); electrodeposition of some protective thin-films based on Ni and Al obtained from ionic liquids; development of some procedures related to the activities involved in the behaviour evaluation, in LFR specific conditions, for material samples subjected to treatments by surface engineering techniques using the LEad COrrosion TEsting LOop (LECOTELO) test bench. The superficial structures obtained have been characterized by metallographic microscopy, X-Ray Photoemission Spectroscopy (XPS), Electrochemical Impedance Spectroscopy (EIS); the electrochemical techniques were used to evaluate the corrosion behaviour. The preliminary results have shown that the used electrochemical surface engineering techniques are appropriate in order to improve the mechanical properties and corrosion behaviour of AISI 316 L steel. (authors)

  9. Experimental study on electrochemical corrosion of FV520B in natural gas environment

    Directory of Open Access Journals (Sweden)

    Juyi Pan

    Full Text Available The electrochemical corrosion of the FV520B stainless steel for natural gas compressor impeller is studied by means of the uniform experimental method. The electrochemical corrosion potential, current density and Tafel slope of the material are measured, and the polarization resistance is solved. The experimental results show that FV520B material does not appear passivation area in the presence of the natural gas environment with H2S, and the material has been in the activation and dissolved state. When the temperature is below 130 °C, the corrosion is dominated by the process of the anode reaction, the concentration of H2S is the decisive factor to determine the occurrence of stress corrosion, the increase of H2S concentration significantly accelerates the corrosion process of the specimen, CO2 inhibits the occurrence of the stress corrosion to a certain extent. Keywords: FV520B, Stress corrosion, Electrochemical corrosion, Natural gas

  10. Corrosion behaviour of 6063 aluminium alloy in acidic and in alkaline media

    Directory of Open Access Journals (Sweden)

    Prabhu Deepa

    2017-05-01

    Full Text Available The corrosion behaviour of 6063 aluminium alloy was investigated in different concentrations of phosphoric acid medium and sodium hydroxide medium at different temperatures. The study was done by electrochemical method, using Tafel polarization technique and electrochemical impedance spectroscopy (EIS technique. The surface morphology was investigated using scanning electron microscope (SEM with Energy-dispersive X-ray spectroscopy (EDX. The results showed that the 6063 aluminium alloy undergoes severe corrosion in sodium hydroxide medium than in phosphoric acid medium. The corrosion rate of 6063 aluminium alloy increased with an increase in the concentration of acid as well as with alkali. The corrosion rate was increased with an increase in temperature. The kinetic parameters and thermodynamic parameters were calculated using Arrhenius theory and transition state theory. Suitable mechanism was proposed for the corrosion of 6063 aluminium alloy in phosphoric acid medium and sodium hydroxide medium. The results obtained by Tafel polarization and electrochemical impedance spectroscopy (EIS techniques were in good agreement with each other.

  11. Modelling the long-term corrosion behaviour of candidate alloys for Canadian SCWR

    Energy Technology Data Exchange (ETDEWEB)

    Steeves, G.; Cook, W., E-mail: wcook@unb.ca, E-mail: graham.steeves@unb.ca [University of New Brunswick, Department of Chemical Engineering, Fredericton, NB (Canada)

    2015-07-01

    Corrosion behaviour of Inconel 625 and Incoloy 800H, two of the candidate fuel cladding materials for Canadian supercritical water (SCW) reactor designs, were evaluated by exposing the metals to SCW in UNB's SCW flow loop. Individual experiments were conducted over a range of 370{sup o}C and 600{sup o}C. Exposure times were typically intervals of 100, 250, and 500 hours. Experimental data was used to create an empirical kinetic equation for each material. Activation energies for the alloys were determined, and showed a distinct difference between low-temperature electrochemical corrosion mechanism and direct high-temperature chemical oxidation. (author)

  12. Effect of cerium on the corrosion behaviour of sintered (Nd,Ce)FeB magnet

    Science.gov (United States)

    Yang, Lijing; Bi, Mengxue; Jiang, Jianjun; Ding, Xuefeng; Zhu, Minggang; Li, Wei; Lv, Zhongshan; Song, Zhenlun

    2017-06-01

    For the balanced consumption of rare-earth elements, cerium (Ce) was partially used for NdFeB magnets instead of Nd. The corrosion behaviour of the (Nd,Ce)FeB magnet with different Ce contents in 3.5% NaCl solution was investigated by SEM, XRD, EDS and electrochemical tests. After immersion, the weight loss was calculated and the magnetic properties of the samples were measured. Results showed that Ce affected the corrosion of the (Nd,Ce)FeB magnet. Compared with the NdFeB magnet without Ce but of the same grade as the magnetic energy product, (Nd,Ce)FeB magnet showed better corrosion resistance. With increased Ce content, the corrosion resistances and magnetic properties of (Nd,Ce)FeB magnets were investigated.

  13. Application of electrochemical methods in corrosion and battery research

    Science.gov (United States)

    Sun, Zhaoli

    Various electrochemical methods have been applied in the development of corrosion protection methods for ammonia/water absorption heat pumps and the evaluation of the stability of metallic materials in Li-ion battery electrolyte. Rare earth metal salts (REMSs) and organic inhibitors have been evaluated for corrosion protection of mild steel in the baseline solution of 5 wt% NH 3 + 0.2 wt% NaOH to replace the conventionally used toxic chromate salt inhibitors. Cerium nitrate provided at least comparable corrosion inhibition efficiency as dichromate in the baseline solution at 100°C. The cerium (IV) oxide formed on mild steel through the cerating process exhibited increasing corrosion protection for mild steel with prolonged exposure time in the hot baseline solution. The optimum cerating process was found to be first cerating in a solution of 2.3 g/L CeCl3 + 4.4 wt% H2O2 + appropriate additives for 20 minutes at pH 2.2 at room temperature with 30 minutes solution aging prior to use, then sealing in 10% sodium (meta) silicate or sodium molybdate at 50°C for 30 minutes. Yttrium salts provided less corrosion protection for mild steel in the baseline solution than cerium salts. Glycerophosphate was found to be a promising chromate-free organic inhibitor for mild steel; however, its thermostability in hot ammonia/water solutions has not been confirmed yet. The stability of six metallic materials used in Li-ion batteries has been evaluated in 1M lithium hexafluorophosphate (LiPF6) dissolved in a 1:1 volume mixture of ethylene carbonate and diethyl carbonate at 37°C in a dry-box. Aluminum is the most stable material, while Copper is active under anodic potentials and susceptible to localized corrosion and galvanic corrosion. The higher the concentration of the alloying elements Al and/or V in a titanium alloy, the higher was the stability of the titanium alloy in the battery electrolyte. 90Pt-10Ir can cause decomposition of the electrolyte resulting in a low stable

  14. Comparison of electrochemical techniques during the corrosion of X52 pipeline steel in the presence of sulfate reducing bacteria (SRB)

    Energy Technology Data Exchange (ETDEWEB)

    Galvan-Martinez, R.; Genesca, J. [Universidad Nacional Autonoma de Mexico (UNAM), Facultad de Quimica, Depto. de Ingenieria Metalurgica, Ciudad Universitaria. Mexico DF, CP 04510 (Mexico); Garcia-Caloca, G.; Duran-Romero, R.; Mendoza-Flores, J. [Instituto Mexicano del Petroleo, Direccion Ejecutiva de Exploracion y Produccion, Corrosion, Eje Central Lazaro Cardenas 152, Mexico D.F., 07730 (Mexico); Torres-Sanchez, R. [Universidad Michoacana de San Nicolas de Hidalgo, Instituto de Investigaciones, Metalurgicas. Edificio ' ' U' ' , C.U. Morelia, Michoacan (Mexico)

    2005-10-01

    This work compares three electrochemical techniques, linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN), used in the study of corrosion of X52 steel samples in an environment containing a culture of sulfate reducing bacteria (SRB). The study emphasizes the different electrochemical information obtained when using these techniques in microbiologically influenced corrosion (MIC) studies. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  15. Benchmarking of Zinc Coatings for Corrosion Protection: A Detailed Characterization of Corrosion and Electrochemical Properties of Zinc Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wijesinghe, Sudesh L; Zixi, Tan [Singapore Institute of Manufacturing Technology, Nanyang Drive (Singapore)

    2017-02-15

    Due to various types of Zn coatings for many decades for various applications, it is imperative to study and compare their corrosion resistance properties of some of these. Here, we introduce a systematic methodology for evaluation and validation of corrosion protection properties of metallic coatings. According to this methodology, samples are were exposed in an advanced cyclic corrosion test chamber according to ISO 14993, and removed at the end of each withdrawal for respective corrosion and electrochemical characterization to evaluate both barrier and galvanic protection properties. Corrosion protection properties of coatings were evaluated by visual examination according to ISO 10289, mass loss and subsequent corrosion rate measurements, electrochemical properties, and advanced electrochemical scanning techniques. In this study, corrosion protection properties of a commercial zinc rich coating (ZRC) on AISI 1020 mild steel substrates were evaluated and benchmarked against hot dip galvanized (HDG). Results were correlated, and corrosion protection capabilities of the two coatings were compared. The zinc rich coating performed better than hot dip galvanized coating in terms of overall corrosion protection properties, according to the exposure and experimental conditions used in this study. It proved to be a suitable candidate to replace hot dip galvanized coatings for desired applications.

  16. Corrosion behaviour of cobalt-chromium dental alloys doped with precious metals.

    Science.gov (United States)

    Reclaru, Lucien; Lüthy, Heinz; Eschler, Pierre-Yves; Blatter, Andreas; Susz, Christian

    2005-07-01

    Precious metal based dental alloys generally exhibit a superior corrosion resistance, in particular enhanced resistance to pitting and crevice corrosion, compared to non-precious metal based alloys such as CoCr alloys. A new generation of Co-Cr alloys enriched with precious metals (Au, Pt, Ru) have now appeared on the market. The goal of this study was to clarify the effect of the precious metals additions on the corrosion behaviour of such alloys. Various commercial alloys with different doping levels were tested by electrochemical techniques in two different milieus based on the Fusayama artificial saliva and an electrolyte containing NaCl. Open circuit potentials, corrosion currents, polarization resistances, and crevices potentials were determined for the various alloys and completed by a coulometric analysis of the potentiodynamic curves. In addition, the microstructures were characterised by metallography and phase compositions analysed by EDX. The results show that the presence of precious metals can deteriorate the corrosion behaviour of Co-Cr alloys in a significant way. Gold doping, in particular, produces heterogeneous microstructures that are vulnerable to corrosive attack.

  17. Corrosion behaviour, microstructure and phase transitions of Zn ...

    Indian Academy of Sciences (India)

    Unknown

    The corrosion tests are carried out both in acidic medium using 1 N HCl solution and in temperature dependence of thermogravimetric analysis (TGA). In the two dif- ferent media, in particular, the corrosion behaviour of Zn-based alloys with respect to Al and Si contents is examined, and microstructure in acidic and TGA and ...

  18. Corrosion behaviour, microstructure and phase transitions of Zn ...

    Indian Academy of Sciences (India)

    This paper is aimed at investigating the corrosion behaviour, microstructure and phase transitions of Zn-based alloys with different compositions. The corrosion tests are carried out both in acidic medium using 1 N HCl solution and in temperature dependence of thermogravimetric analysis (TGA). In the two different media, ...

  19. Local radiolysis and electrochemical corrosion potential in crevice environment

    International Nuclear Information System (INIS)

    Wada, Yoichi; Watanabe, Atsushi; Ishida, Kazushige; Tachibana, Masahiko; Shigenaka, Naoto; Kawashima, Norio; Aizawa, Motohiro

    2012-09-01

    Effects of γ-ray irradiation upon crevice corrosion (CC) of type 316L stainless steel (316L SS) as an initiation site of stress corrosion cracking in a boiling water reactor (BWR) environment have been studied using a material corrosion test loop which could be irradiated with a 60 Co γ-ray source during testing. The CC tests were conducted using crevice specimens with various crevice gaps. Scanning electron microscope observations showed that many specimen surfaces exhibited a selective grain boundary dissolution, that is intergranular attack (IGA) as a result of the CC when the crevice gap was narrower than a certain value. The initiation of IGA was accelerated by either simulated corrosion product filling or γ-ray irradiation. When γ-rays were present, the IGA was observed in a shorter immersion time than the no-irradiation condition. In the γ-ray irradiation environment, Fe oxide on the crevice specimen surface was highly oxidized and strongly adhered to the base metal. Electrochemical corrosion potentials (ECPs) inside crevice specimens were also measured under various crevice gap conditions without irradiation in order to understand the CC mechanism in high temperature water. The narrower the crevice gap of the 316L specimens was, the lower the internal ECP was. Based on comparison with the CC test results, it was concluded that the IGA occurred in the gap where the internal ECP was below -0.4 V vs SHE and difference between internal and external ECPs were very large. Even for γ-ray irradiation at 10 4 Gy/h, the internal ECP was estimated to be low since the assumed maximum production rates of radiolytic oxidants were not high enough to get a large cathodic current density in a narrower crevice gap to give high ECP on the crevice walls. However, since the γ-ray irradiation accelerated the corrosion rate of the SS inside a crevice, the ECP must not be a unique parameter governing the CC. It was assumed that oxidation of Fe 2+ ion in water near the

  20. Corrosion-electrochemical behavior of zirconium in molten alkali metal carbonates

    Science.gov (United States)

    Nikitina, E. V.

    2016-08-01

    The corrosion and electrochemical characteristics of zirconium during its interaction with molten lithium, sodium, and potassium carbonates containing from 1 to 5 wt % additives to the salt phase are studied in a temperature range of 500-800°C using gravimetry, corrosion potential measurement, and anodic polarization. The substances decreasing the corrosion losses due to the strengthening and thickening of an oxide film (lithium, sodium, potassium hydroxides) are used as passivators. Sodium chloride, fluoride, and sulfate serve as corrosion stimulators (activators).

  1. Effect of Cu content on exfoliation corrosion and electrochemical corrosion of A7N01 aluminum alloy in EXCO solution

    Science.gov (United States)

    He, Yaling; Wang, Xiaomin; Hu, Jie; Zhou, Qiang; Chen, Hui

    2017-07-01

    The exfoliation corrosion (EXCO) sensitivities and electrochemical corrosions of A7N01 aluminum (Al) alloys with 0.074% and 0.136% Cu contents were investigated in EXCO solution. The exfoliation corrosion developed more rapidly for the alloy with 0.136% Cu by expressing higher exfoliation rate and deeper corrosion pits as observed by SEM and laser confocal scanning microscopy (LCSM). In EXCO solution, the alloy with 0.136% Cu content showed lower open-circuit potential (OCP) than the alloy with 0.074% Cu content. The alloy with 0.136% Cu content had bigger “hysteresis loop” in cyclic polarization curve which meant lower self-passivation ability. In electrochemical impedance spectroscopy plot, its curvature radius and capacitance index were lower. The electrochemical test results revealed that the alloy with 0.136% Cu content showed more severe electrochemical corrosion than the alloy with 0.074% Cu content, consistent with the exfoliation corrosion results. The microstructures of two alloys were observed through optical microscopy (OM) and transmission electron microscopy (TEM). The continuous distribution of the equilibrium precipitate η-MgZn2 on grain boundaries, the decreasing of the width of precipitate-free zone (PFZ) and the coarse Cu-Fe-Si-rich phase were responsible for the higher corrosion sensitivity of the Al alloy with 0.136% Cu than that of Al alloy with 0.074% Cu content in EXCO solution.

  2. Reliability of Electrochemical Techniques for Determining Corrosion Rates on Carbon Steel in Sulfide Media

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Hemmingsen, T.; Nielsen, Lars Vendelbo

    2007-01-01

    Effects of film formation on carbon steel in hydrogen sulfide (H2S) media may corrupt corrosion rate monitoring by electrochemical techniques. Electrochemical data from H2S solutions, biological sulfide media, and natural sulfide containing geothermal water have been collected, and the process of...... techniques like electrical resistance or mass loss should be used instead.......Effects of film formation on carbon steel in hydrogen sulfide (H2S) media may corrupt corrosion rate monitoring by electrochemical techniques. Electrochemical data from H2S solutions, biological sulfide media, and natural sulfide containing geothermal water have been collected, and the process...... if the biofilm in combination with ferrous sulfide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 with electrochemical techniques - both by linear polarization resistance (LPR) and electrochemicel impedance spectroscopy (EIS). Oxygen entering the system...

  3. Effect of cerium on the corrosion behaviour of sintered (Nd,Ce)FeB magnet

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lijing [CAS Key Laboratory of Magnetic Materials and Devices, Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Bi, Mengxue [CAS Key Laboratory of Magnetic Materials and Devices, Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Nano Science and Technology Institute, University of Science and Technology of China, Hefei 230026 (China); Jiang, Jianjun; Ding, Xuefeng [CAS Key Laboratory of Magnetic Materials and Devices, Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhu, Minggang; Li, Wei [Functional Materials Research Institute, Central Iron & Steel Research Institute, Beijing 100081 (China); Lv, Zhongshan [Ningbo Shuo Teng new material Co., Ltd., Cixi 315301 (China); Song, Zhenlun, E-mail: songzhenlun@nimte.ac.cn [CAS Key Laboratory of Magnetic Materials and Devices, Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2017-06-15

    Highlights: • A little Ce could promote the magnets for a better corrosion resistance. • With increased Ce contents, the corrosion resistances of magnets decrease. • As the corrosion developed, the magnetic properties decreased. - Abstract: For the balanced consumption of rare-earth elements, cerium (Ce) was partially used for NdFeB magnets instead of Nd. The corrosion behaviour of the (Nd,Ce)FeB magnet with different Ce contents in 3.5% NaCl solution was investigated by SEM, XRD, EDS and electrochemical tests. After immersion, the weight loss was calculated and the magnetic properties of the samples were measured. Results showed that Ce affected the corrosion of the (Nd,Ce)FeB magnet. Compared with the NdFeB magnet without Ce but of the same grade as the magnetic energy product, (Nd,Ce)FeB magnet showed better corrosion resistance. With increased Ce content, the corrosion resistances and magnetic properties of (Nd,Ce)FeB magnets were investigated.

  4. Influence of a biopolymer admixture on corrosion behaviour of steel rebars in concrete

    Energy Technology Data Exchange (ETDEWEB)

    Roux, S.; Bur, N.; Feugeas, F. [LGECO - LISS, INSA de Strasbourg, 24 bd de la Victoire, 67 084 Strasbourg Cedex (France); Ferrari, G. [TNO Science and Industry, Bevesierweg, 1781 CA Den Helder (Netherlands); Tribollet, B. [UPR15 du CNRS, LISE, Universite Pierre et Marie Curie, 4 place Jussieu, 75 252 Paris Cedex 05 (France)

    2010-12-15

    Among the multitude of concrete structure pathologies, corrosion of rebars is one of the most important problems of concrete durability. In the context of sustainable development, it appears of primary importance to develop new means to protect the rebars against corrosion. This study aims to develop a new eco-friendly and corrosion-inhibiting admixture based on EPS 180 exopolysaccharides, biopolymers used in coatings already studied for the corrosion inhibition on steel in seawater. C15 rebars embedded in CEMI and CEMV cement paste containing EPS 180 were immersed in natural seawater and their electrochemical behaviour was studied using open circuit potential measurements and electrochemical impedance spectroscopy. These tests highlight the decrease of the cathodic reaction kinetics due to the EPS 180 action at the rebars surface, and the absence of effect on the passive layer. Capillary imbibition tests carried out on cement paste and mortars showed that although limiting the imbibition kinetics for cement pastes, the EPS 180 did not influence the water imbibition of mortars. Tests comparing capillary imbibition of soaked cement pastes and mortars with EPS 180 solution and the same samples containing the EPS 180 admixture highlight that the corrosion inhibition induced by EPS 180 admixture is more due to the modification of the cement - rebars interface than to the clogging of the cement porous network. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Effect of temperature on the corrosion resistance and pitting behaviour of Alloy 31 in LiBr solutions

    Energy Technology Data Exchange (ETDEWEB)

    Blasco-Tamarit, E.; Igual-Munoz, A. [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, P.O. Box 22012, E-46071 Valencia (Spain); Anton, J. Garcia [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, P.O. Box 22012, E-46071 Valencia (Spain)], E-mail: jgarciaa@iqn.upv.es; Garcia-Garcia, D. [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, P.O. Box 22012, E-46071 Valencia (Spain)

    2008-07-15

    The corrosion resistance and pitting behaviour of Alloy 31, a high-alloyed austenitic stainless steel (UNS N08031), is studied in two heavy brine LiBr solutions (850 g/l) with and without corrosion inhibitor (lithium chromate) at different temperatures (25 deg. C, 50 deg. C, 75 deg. C and 100 deg. C) using electrochemical techniques. Cyclic potentiodynamic curves indicate that UNS N08031 is less pitting corrosion resistant and it reduces its repassivation properties as temperature increases. Comparison between the results obtained in LiBr solutions with and without inhibitor suggested a decrease in the inhibitor efficiency of lithium chromate at high temperatures.

  6. Pitting Corrosion Behaviour of New Corrosion-Resistant Reinforcement Bars in Chloride-Containing Concrete Pore Solution

    Science.gov (United States)

    Liu, Yao; Chu, Hong-yan; Wang, Danqian; Ma, Han; Sun, Wei

    2017-01-01

    In this study, the pitting behaviour of a new corrosion-resistant alloy steel (CR) is compared to that of low-carbon steel (LC) in a simulated concrete pore solution with a chloride concentration of 5 mol/L. The electrochemical behaviour of the bars was characterised using linear polarisation resistance (LPR) and electrochemical impedance spectroscopy (EIS). The pitting profiles were detected by reflective digital holographic microscopy (DHM), scanning electron microscopy (SEM), and the chemical components produced in the pitting process were analysed by X-ray energy dispersive spectroscopy (EDS). The results show that the CR bars have a higher resistance to pitting corrosion than the LC bars. This is primarily because of the periodic occurrence of metastable pitting during pitting development. Compared to the pitting process in the LC bars, the pitting depth grows slowly in the CR bars, which greatly reduces the risk of pitting. The possible reason for this result is that the capability of the CR bars to heal the passivation film helps to restore the metastable pits to the passivation state. PMID:28777327

  7. Pitting Corrosion Behaviour of New Corrosion-Resistant Reinforcement Bars in Chloride-Containing Concrete Pore Solution.

    Science.gov (United States)

    Jiang, Jin-Yang; Liu, Yao; Chu, Hong-Yan; Wang, Danqian; Ma, Han; Sun, Wei

    2017-08-04

    In this study, the pitting behaviour of a new corrosion-resistant alloy steel (CR) is compared to that of low-carbon steel (LC) in a simulated concrete pore solution with a chloride concentration of 5 mol/L. The electrochemical behaviour of the bars was characterised using linear polarisation resistance (LPR) and electrochemical impedance spectroscopy (EIS). The pitting profiles were detected by reflective digital holographic microscopy (DHM), scanning electron microscopy (SEM), and the chemical components produced in the pitting process were analysed by X-ray energy dispersive spectroscopy (EDS). The results show that the CR bars have a higher resistance to pitting corrosion than the LC bars. This is primarily because of the periodic occurrence of metastable pitting during pitting development. Compared to the pitting process in the LC bars, the pitting depth grows slowly in the CR bars, which greatly reduces the risk of pitting. The possible reason for this result is that the capability of the CR bars to heal the passivation film helps to restore the metastable pits to the passivation state.

  8. Electrochemical corrosion potential monitoring in boiling water reactors

    International Nuclear Information System (INIS)

    The electrochemical corrosion potential (ECP) is defined as the measured voltage between a metal and a standard reference electrode converted to the standard hydrogen electrode (SHE) scale. This concept is shown schematically in Figure 1. The measurement of ECP is of primary importance for both evaluating the stress corrosion cracking susceptibility of a component and for assuring that the specification for hydrogen water chemistry, ECP < -230 mV, SHE is being met. In practice, only a limited number of measurement locations are available in the BWR and only a few reference electrode types are robust enough for BWR duty. Because of the radiolysis inherent in the BWR, local environment plays an important role in establishing the ECP of a component. This paper will address the strategies for obtaining representative measurements, given these stated limitations and constraints. The paper will also address the ECP monitoring strategies for the noble metal chemical addition process that is being implemented in BWRs to meet the ECP specification at low hydrogen injection rates. (author)

  9. An electrochemical approach to predicting corrosion performance of container materials

    International Nuclear Information System (INIS)

    McCright, R.D.; Farmer, J.C.; Fleming, D.L.

    1991-04-01

    As part of the effort in determining the suitability of the Yucca Mountain site in Southern Nevada for emplacement of high-level nuclear waste in a repository, possible failure modes of candidate waste package container metallic materials are being investigated. Localized forms of corrosion such as pitting attack on the metal surface or attack in creviced areas are particularly pernicious failure modes that may shorten the container lifetime. The pitting potential of nickel-rich Alloy 825 are measured in chloride-containing solutions at different temperatures and adjusted to different pH values. The pitting potentials were determined by potentiodynamic polarization of Alloy 825 test specimens from the corrosion potential until a sharp increase in the electrochemical current indicated a breakdown of the protective passive film on the metal surface. Results show that Alloy 825 is susceptible to pitting attack in aggressive electrolytes containing more than 10,000 ppm chloride at 90 degree C and acicified to a pH value less than 2.5. 5 refs., 3 figs., 1 tab

  10. Evaluation of the Microbiologically Influenced Corrosion in a carbon steel making use of electrochemical techniques

    International Nuclear Information System (INIS)

    Diaz S, A.C.; Arganis, C.; Ayala, V.; Gachuz, M.; Merino, J.; Suarez, S.; Brena, M.; Luna, P.

    2001-01-01

    The Microbiologically Influenced Corrosion (MIC) has been identified as a problem of the nuclear plants systems in the last years. The electrochemical behavior of metal coupons of carbon steel submitted to the action of sulfate reducing bacteria (SRB) was evaluated, making use of the electrochemical techniques of direct current as well as electrochemical noise. The generated results show a little variation in the corrosion velocities which obtained by Tafel extrapolation and resistance to the linear polarization, whereas the electrochemical noise technique presented important differences as regards the registered behavior in environment with and without microorganisms. (Author)

  11. Electrochemical behaviour of ceramic yttria stabilized zirconia on carbon steel synthesized via sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Crespo, M.A. Dominguez, E-mail: mdominguezc@ipn.m [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico); Murillo, A. Garcia; Torres-Huerta, A.M. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico); Yanez-Zamora, C. [Estudiante del postgrado en Tecnologia Avanzada del CICATA-IPN, Unidad Altamira, km 14.5, Carr. Tampico-Puerto Industrial. C.P. 89600, Altamira, Tamaulipas (Mexico); Carrillo-Romo, F. de J [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico)

    2009-08-26

    Chromate conversion coatings have been widely applied for the corrosion of different metallic substrates. However, the waste containing Cr{sup 6+} has many limitations due to the environmental consideration and health hazards. An interesting alternative seems to be the deposition on metallic surface of thin layers of yttria or zirconia or both by the sol-gel process. In this study, Ytttria and Yttria stabilized zirconia (YSZ, 8% Y{sub 2}O{sub 3}) thin films were used for coating commercial carbon steel substrates by sol-gel method and the dip-coating process. The evolution of organic compounds up to crystallization process as a function of heat treatments was study by FT-IR spectroscopy. The structure and morphology of the coatings were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The anticorrosion performance of the coatings has been evaluated by using electrochemical techniques in an aggressive media (3.5 wt.% NaCl). The corrosion behaviour of sol-gel method was compared with traditional chromate conversion coatings. Differences in the electrochemical behaviour of YSZ coatings are related to the development of microcracks during the sintering process and to the presence of organic compounds during growth film. Electrochemical results showed that sol-gel YSZ and Y{sub 2}O{sub 3} coatings can act as protective barriers against wet corrosion; however yttria films displayed low adhesion to substrate. The corrosion parameters provide an explanation of the role of each film and show a considerable increase in the corrosion resistance for coated samples in comparison to the bare steel samples.

  12. An electrochemical study of the corrosion behavior of primer coated 2219-T87 aluminum

    Science.gov (United States)

    Danford, M. D.; Higgins, R. H.

    1985-01-01

    The corrosion behavior for 2219-T87 aluminum coated with various primers, including those used for the external tank and solid rocket boosters of the Space Shuttle Transportation System, were investigated using electrochemical techniques. Corrosion potential time, polarization resistance time, electrical resistance time, and corrosion rate time measurements were all investigated. It was found that electrical resistance time and corrosion rate time measurement were most useful for studying the corrosion behavior of painted aluminum. Electrical resistance time determination give useful information concerning the porosity of paint films, while corrosion rate time curves give important information concerning overall corrosion rates and corrosion mechanisms. In general, the corrosion rate time curves all exhibited at least one peak during the 30 day test period, which was attributed, according to the proposed mechanisms, to the onset of the hydrogen evolution reaction and the beginning of destruction of the protective properties of the paint film.

  13. When can Electrochemical Techniques give Reliable Corrosion Rates on Carbon Steel in Sulfide Media?

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Hemmingsen, Tor; Nielsen, Lars Vendelbo

    2005-01-01

    Effects of film formation on carbon steel in hydrogen sulfide media may corrupt corrosion rate monitoring by electrochemical techniques. Electrochemical data from hydrogen sulfide solutions, biological sulfide media and natural sulfide containing geothermal water have been collected and the process...... of film formation in sulfide solutions was followed by video. It can be shown that capacitative and diffusional effects due to porous reactive deposits tend to dominate the data resulting in unreliable corrosion rates measured by electrochemical techniques. The effect is strongly increased if biofilm...... corrosion rates, but this effect may not be detected if rates are already overestimated. It is concluded that electrochemical techniques can be used for corrosion rate monitoring in som hydrogen sulfide media, but care must be taken when choosing the scan rates, and it is important to realize when direct...

  14. [Evaluation of the corrosion resistance of orthodontic wires by electrochemical measures and scanning electron microscopy (SEM)].

    Science.gov (United States)

    Zoghbi, André El; Klein, Lorena; Frateur, Isabelle

    2013-12-01

    The objective of this paper is to study the corrosion resistance of orthodontic wires made of different alloys (stainless steel, chrome-cobalt, nickel-titanium and β-titanium) and for the same alloy from different vendors (GAC(®), RMO(®), 3M(®) and ORMCO(®)). Different electrochemical techniques (corrosion potential monitoring as a function of immersion time, current-potential curves, electrochemical impedance spectroscopy (EIS)) were used. The wires' resistance to corrosion was measured and compared with the surface condition, assessed by scanning electron microscopy (SEM). Using the recorded data, a rating system based on the corrosion resistance of orthodontic wires was developed. The comparison of these data with the results of SEM shows that the surface chemical composition plays a primary role in the electrochemical behavior of the orthodontic wires and, unlike surface defects, is a key parameter for the corrosion resistance of the alloy. © EDP Sciences, SFODF, 2013.

  15. Comparative evaluation of corrosion behaviour of type K thin film thermocouple and its bulk counterpart

    International Nuclear Information System (INIS)

    Mukherjee, S.K.; Barhai, P.K.; Srikanth, S.

    2011-01-01

    Highlights: → Anodic vacuum arc deposited chromel and alumel films are more 'noble' in 5% NaCl solution than their respective wires. → Chromel undergoes localised corrosion while alumel shows uniform corrosion. → Virgin samples of chromel-alumel TFTCs exhibit good thermoelectric response. → Their thermoelectric outputs remain largely unaffected when shelved under normal atmospheric conditions. → After 288 h of exposure in salt spray environment, their thermoelectric outputs show noticeable change due to size effects. - Abstract: This paper investigates the corrosion behaviour of type K thermoelements and their thin films, and compares the performance of chromel-alumel thin film thermocouple with its wire counterpart before and after exposure to 5% NaCl medium. Potentiodynamic polarisation tests reveal that chromel and alumel films are more 'noble' than their respective wires. Alumel corrodes faster when coupled with chromel in films than as wires. Secondary electron micrographs and electrochemical impedance spectroscopy measurements suggest that chromel shows localised corrosion while alumel undergoes uniform corrosion. Corrosion adversely affects the thermocouple output and introduces an uncertainty in the measurement.

  16. Corrosion behaviour of AISI 304 stainless steel with Cu coatings in H 2SO 4

    Science.gov (United States)

    Pardo, A.; Merino, M. C.; Coy, A. E.; Arrabal, R.; Viejo, F.; M'hich, A.

    2007-09-01

    The work addresses the influence of cementation and electrodeposition of copper coatings on the corrosion resistance of AISI 304 stainless steel immersed in 30 wt.% H 2SO 4 at temperatures of 25 and 50 °C. Corrosion process was evaluated by gravimetric tests, DC measurements and electrochemical impedance spectroscopy (EIS). The specimen surfaces were analysed by scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. The corrosion performance of AISI 304 stainless steel in sulphuric acid solution was greatly improved by copper coatings. The amount of copper deposited by the cementation process was sufficient to protect the stainless steel of corrosion. A greater amount of copper obtained by electrodeposition treatments does not supply further improvement in the corrosion behaviour. The improved corrosion resistance is related to copper dissolution at the initial stages of immersion tests and the presence of Cu 2+ in the solution, which makes the medium more oxidizing, increasing the stability of the passive layer. In addition, the presence of copper at the surface reduces the overpotential of cathodic reaction, enabling the transition from an active region to the passive one.

  17. Electrochemical Corrosion Studies for Modeling Metallic Waste Form Release Rates

    Energy Technology Data Exchange (ETDEWEB)

    Poineau, Frederic [Univ. of Nevada, Las Vegas, NV (United States); Tamalis, Dimitri [Florida Memorial Univ., Miami Gardens, FL (United States)

    2016-08-01

    The isotope 99Tc is an important fission product generated from nuclear power production. Because of its long half-life (t1/2 = 2.13 ∙ 105 years) and beta-radiotoxicity (β⁻ = 292 keV), it is a major concern in the long-term management of spent nuclear fuel. In the spent nuclear fuel, Tc is present as an alloy with Mo, Ru, Rh, and Pd called the epsilon-phase, the relative amount of which increases with fuel burn-up. In some separation schemes for spent nuclear fuel, Tc would be separated from the spent fuel and disposed of in a durable waste form. Technetium waste forms under consideration include metallic alloys, oxide ceramics and borosilicate glass. In the development of a metallic waste form, after separation from the spent fuel, Tc would be converted to the metal, incorporated into an alloy and the resulting waste form stored in a repository. Metallic alloys under consideration include Tc–Zr alloys, Tc–stainless steel alloys and Tc–Inconel alloys (Inconel is an alloy of Ni, Cr and iron which is resistant to corrosion). To predict the long-term behavior of the metallic Tc waste form, understanding the corrosion properties of Tc metal and Tc alloys in various chemical environments is needed, but efforts to model the behavior of Tc metallic alloys are limited. One parameter that should also be considered in predicting the long-term behavior of the Tc waste form is the ingrowth of stable Ru that occurs from the radioactive decay of 99Tc (99Tc → 99Ru + β⁻). After a geological period of time, significant amounts of Ru will be present in the Tc and may affect its corrosion properties. Studying the effect of Ru on the corrosion behavior of Tc is also of importance. In this context, we studied the electrochemical behavior of Tc metal, Tc-Ni alloys (to model Tc-Inconel alloy) and Tc-Ru alloys in acidic media. The study of Tc-U alloys has also been performed in order to better understand the

  18. Temperature Effect on the Corrosion Behaviour of Alloy 31 in polluted H3PO4 and Analysis of the Corrosion Products by Laser Raman Microscope

    OpenAIRE

    Escrivá Cerdán, Clara; Blasco-Tamarit, E.; García-García, D.M.; Garcia-Anton, Jose; Ben-Bachir, A.

    2012-01-01

    Electrochemical behaviour of Alloy 31, a highly alloyed austenitic stainless steel (UNS N08031), in a 40 wt.% H3PO4 solution polluted with 2 wt.% H2SO4, 0.06 wt.% KCl and 0.6 wt.% HF was evaluated by cyclic potentiodinamic curves at different temperatures (20, 40, 60 and 80 degrees C). Temperature was found to favour both cathodic and anodic reactions. The corrosion products forming on the surface of Alloy 31 were indentified in situ by Laser Raman microscope. Corrosion products were mainly i...

  19. Wear and corrosion behaviour of Al2O3-TiO2 coatings produced by flame thermal projection

    Science.gov (United States)

    Forero-Duran, M.; Dulce-Moreno, H. J.; Ferrer-Pacheco, M.; Vargas-Galvis, F.

    2017-12-01

    Evaluated the wear resistance and the coatings corrosion behaviour of Al2O3-TiO2 prepared by thermal spraying by flame on AISI 1020 carbon steel substrates, previously coated with an alloy base Ni. For this purpose, were controlled parameters of thermal spraying and the use of powders of similar but different chemical composition is taken as a variable commercial reference for ceramic coating. SEM images allowed to know the morphology of the powders and coatings. Electrochemical techniques (Tafel) were applied to evaluate the protection against corrosion. Coatings were tested for wear with a tribometer configuration bola-disco. It was determined that the phases present in coatings are directly relate to the behaviour against corrosion and wear them. Keywords: wear, corrosion, thermal imaging.

  20. Effects of sulphur ion implantation on the electrochemical behaviour of two stainless steels in sulphuric medium

    International Nuclear Information System (INIS)

    Nader-Roux, J.; Becdelievre, A.M. de; Gaillard, F.; Roux, R.; Becdelievre, J. de

    1986-01-01

    The electrochemical behaviour in sulphuric acid of two austenitic stainless steels (AISI 304 L and AISI 321) modified by sulphur ion implantation has been studied. Surface analysis of oxygen and sulphur by LEEIXS and XRFS were performed before and after polarization on unimplanted and on implanted samples. I/E curves with implanted steels reveal an important corrosion peak (α peak) recovering widely the active peak of unimplanted samples. For high implanted doses, another peak (β peak) appears in the passive range. High doses implanted steels polarized in the range of the α peak exhibit a sulphur enriched black surface layer. SEM examination of this layer shows it is constituted by flakes rolling up themselves. The formation of a superficial non-protective sulphide layer and the internal stresses of this layer explain the corrosion enhancement of sulphur implanted materials. After dissolution of this layer the behaviour of unimplanted steels is found again. (author)

  1. Electrochemical methods for characterisation of thermal spray corrosion resistant stainless steel coatings

    NARCIS (Netherlands)

    Hofman, R.; Vreijling, M.P.W.; Ferrari, G.M.; Wit, J.H.W. de

    1998-01-01

    The use of thermal spray stainless steel coatings for protection of low alloyed steels against different types of corrosion is limited due to high porosity levels and oxide inclusions. In this paper electrochemical methods like corrosion potential monitoring and cyclic voltammetry are reported to

  2. ELECTROCHEMICAL CORROSION STUDIES CORE 308 SEGMENTS 14R1 & 14R2 TANK 241-AY-102

    Energy Technology Data Exchange (ETDEWEB)

    DUNCAN JB; COOKE GA

    2003-10-30

    This document reports the results of electrochemical corrosion tests on AS1S Grade 60 carbon steel coupons exposed to tank 241-AY-102 sludge under conditions similar to those near the bottom of the tank. The tests were performed to evaluate the corrosive behavior of the waste in contact with sludge that does not meet the chemistry control limits of Administrative Control (AC) 5.15, Corrosion Mitigation Program.

  3. Reliability of Electrochemical Techniques for Determining Corrosion Rates on Carbon Steel in Sulfide Media

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Hemmingsen, T.; Nielsen, Lars Vendelbo

    2007-01-01

    Effects of film formation on carbon steel in hydrogen sulfide (H2S) media may corrupt corrosion rate monitoring by electrochemical techniques. Electrochemical data from H2S solutions, biological sulfide media, and natural sulfide containing geothermal water have been collected, and the process of...

  4. Microstructure and mechanical properties of friction welded AISI 1040/AISI 304L steels before and after electrochemical corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Sarsilmaz, Furkan [Firat Univ., Elazig (Turkey). Dept. of Mechatronics Engineering; Kirik, Ihsan [Batman Univ. (Turkey); Ozdemir, Niyazi [Firat Univ., Elazig (Turkey)

    2018-03-01

    The aim of the present study is to investigate the effect of welding parameters both on the electrochemical corrosion behavior and tensile strength of pre- and post-electrochemical corrosion of friction welded dissimilar steels. The microstructural changes of AISI 1040/AISI 304L friction welded couples and also parent materials were analyzed by using scanning electron microscopy. The electrochemical behaviors of AISI1040/AISI304L joints were comparatively investigated by potentiodynamic polarization curve test and by electrochemical impedance spectra. Moreover, tensile strength experiments were carried out determining the behavior of friction welded joints of pre- and post-electrochemical corrosion and results indicated that the maximum tensile test value of the dissimilar welded pre-electrochemical corrosion was higher than those of post-electrochemical corrosion and was also very close to AISI 1040 parent material value.

  5. Wear and corrosion behaviour of tungsten carbide based coatings with different metallic binder

    Science.gov (United States)

    Kamdi, Z.; Apandi, M. N. M.; Ibrahim, M. D.

    2017-12-01

    Tungsten carbide based coating has been well known as wear and corrosion resistance materials. However, less study is done on comparing the coating with different binder. Thus, in this work the wear and corrosion behaviour of high velocity oxy-fuel (HVOF) coatings, namely (i) tungsten carbide cobalt and (ii) tungsten carbide nickel will be evaluated. Both coatings were characterised using X-ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). The wear behaviour has been examined using the modified grinder machine by weight loss measurement. Two types of abrasive have been used that include 3 g by weight alumina and silica. While for the corrosion behaviour, it is monitored by three electrodes of electrochemical test and immersion test for 30 days in an acidic environment. The electrolyte used was 0.5 M sulphuric acids (H2SO4). It was found that the cobalt binder shows higher wear resistance compares to the nickel binder for both slurry types. The harder alumina compared to silica results in higher wear rate with removal of carbide and binder is about the same rate. For silica abrasive, due to slightly lower hardness compared to the carbide, the wear is dominated by binder removal followed by carbide detachment. For corrosion, the nickel binder shows four times higher wear resistance compared to the cobalt binder as expected due to its natural behaviour. These finding demonstrate that the selection of coating to be used in different application in this case, wear and corrosion shall be chosen carefully to maximize the usage of the coating.

  6. Corrosion behaviours of the dental magnetic keeper complexes made by different alloys and methods.

    Science.gov (United States)

    Wu, Min-Ke; Song, Ning; Liu, Fei; Kou, Liang; Lu, Xiao-Wen; Wang, Min; Wang, Hang; Shen, Jie-Fei

    2016-09-29

    The keeper and cast dowel-coping, as a primary component for a magnetic attachment, is easily subjected to corrosion in a wet environment, such as the oral cavity, which contains electrolyte-rich saliva, complex microflora and chewing behaviour and so on. The objective of this in vitro study was to examine the corrosion resistance of a dowel and coping-keeper complex fabricated by finish keeper and three alloys (cobalt-chromium, CoCr; silver-palladium-gold, PdAu; gold-platinum, AuPt) using a laser-welding process and a casting technique. The surface morphology characteristics and microstructures of the samples were examined by means of metallographic microscope and scanning electron microscope (SEM). Energy-dispersive spectroscopy (EDS) with SEM provided elements analysis information for the test samples after 10% oxalic acid solution etching test. Tafel polarization curve recordings demonstrated parameter values indicating corrosion of the samples when subjected to electrochemical testing. This study has suggested that massive oxides are attached to the surface of the CoCr-keeper complex but not to the AuPt-keeper complex. Only the keeper area of cast CoCr-keeper complex displayed obvious intergranular corrosion and changes in the Fe and Co elements. Both cast and laser-welded AuPt-keeper complexes had the highest free corrosion potential, followed by the PdAu-keeper complex. We concluded that although the corrosion resistance of the CoCr-keeper complex was worst, the keeper surface passive film was actually preserved to its maximum extent. The laser-welded CoCr- and PdAu-keeper complexes possessed superior corrosion resistance as compared with their cast specimens, but no significant difference was found between the cast and laser-welded AuPt-keeper complexes. The Fe-poor and Cr-rich band, appearing on the edge of the keeper when casting, has been proven to be a corrosion-prone area.

  7. Electrochemical Corrosion of Stainless Steel in Thiosulfate Solutions Relevant to Gold Leaching

    Science.gov (United States)

    Choudhary, Lokesh; Wang, Wei; Alfantazi, Akram

    2016-01-01

    This study aims to characterize the electrochemical corrosion behavior of stainless steel in the ammoniacal thiosulfate gold leaching solutions. Electrochemical corrosion response was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy, while the semi-conductive properties and the chemical composition of the surface film were characterized using Mott-Schottky analysis and X-ray photoelectron spectroscopy, respectively. The morphology of the corroded specimens was analyzed using scanning electron microscopy. The stainless steel 316L showed no signs of pitting in the ammoniacal thiosulfate solutions.

  8. Corrosion Behaviour of New Zr Alloys

    DEFF Research Database (Denmark)

    Tolksdorf, E.

    1974-01-01

    Corrosion studies have indicated that the most promising replacements for Zicaloy-2 are ZrCrFe, ZrVFe and probably ZrNbTa, provided they are in their optimized condition. These alloys are conventionally manufactured alloys. An internally oxidized ZrMgO alloy is even superior, from the corrosion...... and hydrogen uptake points of view, to the above-mentioned alloys. This alloy is of particular interest because the addition of MgO leads to no neutron penalty and the dispersion-strengthening entails the possibility of tailoring an alloy with the desired mechanical properties....

  9. Corrosion behaviour of zinc deposits obtained under pulse current electrodeposition: Effects of coumarin as additive

    International Nuclear Information System (INIS)

    Mouanga, M.; Ricq, L.; Douglade, J.; Bercot, P.

    2009-01-01

    The corrosion behaviour of zinc deposits obtained under pulsed current electrodeposition from an acidic chloride bath in the presence and absence of coumarin has been investigated. The effects of pulse peak current density (J p ) on the morphology of zinc deposits were studied by scanning electron microscopy. An increase in J p from 40 to 280 A dm -2 yields deposits with a finer grain size. The refinement of the grain size was more considerable in the presence of coumarin (J p = 280 A dm -2 ). The preferred orientation of zinc deposits was studied by X-ray diffraction. At J p = 40 A dm -2 , the preferred orientation of zinc deposits was (1 0 3) and changed to (0 0 2) at J p = 80 A dm -2 . An increase in J p to 280 A dm -2 did not change the preferred crystallographic orientations except for an increase in the peak intensity of the (0 0 2) plane. In the presence of coumarin, the preferred crystallographic orientations changed at J p = 280 A dm -2 from the (0 0 2) plane to the (1 0 3) plane. The corrosion behaviour was investigated in an aerated 3.5% NaCl solution; the anodic polarization and electrochemical impedance spectroscopy curves were performed. The corrosion resistance of zinc deposits was improved by increasing the pulse peak current density (J p ); whereas, the presence of coumarin did not improve the corrosion resistance

  10. Anodized titanium and stainless steel in contact with CFRP: an electrochemical approach considering galvanic corrosion.

    Science.gov (United States)

    Mueller, Yves; Tognini, Roger; Mayer, Joerg; Virtanen, Sannakaisa

    2007-09-15

    The combination of different materials in an implant gives the opportunity to better fulfill the requirements that are needed to improve the healing process. However, using different materials increases the risk of galvanic coupling corrosion. In this study, coupling effects of gold-anodized titanium, stainless steel for biomedical applications, carbon fiber reinforced polyetheretherketone (CFRP), and CFRP containing tantalum fibers are investigated electrochemically and by long-term immersion experiments in simulated body fluid (SBF). Potentiodynamic polarization experiments (i/E curves) and electrochemical impedance spectroscopy (EIS) of the separated materials showed a passive behavior of the metallic samples. Anodized titanium showed no corrosion attacks, whereas stainless steel is highly susceptibility for localized corrosion. On the other side, an active dissolution behavior of both of the CFRPs in the given environment could be determined, leading to delaminating of the carbon fibers from the matrix. Long-term immersion experiments were carried out using a set-up especially developed to simulate coupling conditions of a point contact fixator system (PC-Fix) in a biological environment. Electrochemical data were acquired in situ during the whole immersion time. The results of the immersion experiments correlate with the findings of the electrochemical investigation. Localized corrosion attacks were found on stainless steel, whereas anodized titanium showed no corrosion attacks. No significant differences between the two CFRP types could be found. Galvanic coupling corrosion in combination with crevice conditions and possible corrosion mechanisms are discussed. Copyright 2007 Wiley Periodicals, Inc.

  11. Characterization of the behaviour of electro-galvanised steel sheets in terms of corrosion

    International Nuclear Information System (INIS)

    Finoly, Guylene

    1992-01-01

    This research thesis reports the development of a test method for the characterization of the behaviour of electro-galvanised steel sheets (i.e. zinc coated steel sheets as those used in the automotive industry) with respect to corrosion, and the definition of a classification of these materials with respect to their surface activity. After an overview of the different existing methods of determination of corrosion rate, the author reports the development of an experimental device adapted to the electrochemical study of electro-galvanised sheets, i.e. adapted to their low thickness (0,7 mm) and coating characteristics (10 μm thick). This device is then used in the case of solid zinc. The authors reports the study of the behaviour of sheets in a NaCl solution in order to meet industrial conditions used to activate the surface before the phosphate conversion process which aims at ensuring paint adherence. A test is proposed and validated by comparison with other electrochemical or chemical methods, and used to study the behaviour of electro-galvanised sheets submitted to a phosphate conversion coating process [fr

  12. Multiscale Electrochemical Investigation of the Corrosion Resistance of Various Alloys Used in Dental Prostheses

    Science.gov (United States)

    Iacoban, Sorin; Mareci, Daniel; Bolat, Georgiana; Munteanu, Corneliu; Souto, Ricardo Manuel

    2015-04-01

    The electrochemical behavior of Ag-Pd (Paliag), Ni-Cr (Heraenium NA), and Co-Cr (Heraenium CE) alloys used in dental prosthetics construction of crowns and bridges was studied in 0.9 pct NaCl solution at 298 K (25 °C). The localized electrochemical characteristics related to corrosion resistance and eventual breakdown of the protecting oxide layers were investigated by scanning electrochemical microscopy (SECM), whereas potentiodynamic polarization and electrochemical impedance spectroscopy techniques were employed to establish oxide stability. When the corrosion resistance of the alloys was evaluated by means of the corrosion current value determined around their corresponding open circuit potential in 0.9 pct NaCl solution, good protection can be expected resulting from their spontaneous passivation (low current densities in the order of tenths of μA cm-2). The polarization resistance of all the samples increased with immersion time, in the sequence Ag-Pd Ag-Pd instead.

  13. Electrochemical supercapacitor behaviour of functionalized candle ...

    Indian Academy of Sciences (India)

    diamond) and G (graphite) phase of carbon present in the candle soots. The electrochemical characterization was performed by cyclic voltammetry, galvanostatic charge/discharge test and impedance spectroscopy in 1MH2SO4 electrolyte.

  14. The effect of PVD coatings on the corrosion behaviour of AZ91 magnesium alloy

    International Nuclear Information System (INIS)

    Altun, Hikmet; Sen, Sadri

    2006-01-01

    In this study, multilayered AlN (AlN + AlN + AlN) and AlN + TiN were coated on AZ91 magnesium alloy using physical vapour deposition (PVD) technique of DC magnetron sputtering, and the influence of the coatings on the corrosion behaviour of the AZ91 alloy was examined. A PVD system for coating processes, a potentiostat for electrochemical corrosion tests, X-ray difractometer for compositional analysis of the coatings, and scanning electron microscopy for surface examinations were used. It was determined that PVD coatings deposited on AZ91 magnesium alloy increased the corrosion resistance of the alloy, and AlN + AlN + AlN coating increased the corrosion resistance much more than AlN + TiN coating. However, it was observed that, in the coating layers, small structural defects e.g., pores, pinholes, cracks that could arise from the coating process or substrate and get the ability of protection from corrosion worsened were present

  15. Electrochemical corrosion of Zircaloy-2 under PWR water chemistry but at room temperature

    International Nuclear Information System (INIS)

    Waheed, Abdel-Aziz Fahmy; Kandil, Abdel-Hakim Taha; Hamed, Hani M.

    2016-01-01

    Highlights: • There is no simple relation between the corrosion rate and LiOH concentration. • At low concentration, 100 ppm Li, an increase of the rate is due to the pH impact. • LiOH in concentrated solution led to accelerated corrosion by pH effect and porosity. • Boron abates the lithium effect by pH neutralizing and participation in the corrosion. - Abstract: Electrochemical corrosion of Zircaloy-2 was tested at room temperature in lithium hydroxide (LiOH) concentrations that ranged from 2.2 to 7000 ppm and boric acid (H 3 BO 3 ) concentrations that ranged from 50 to 4000 ppm. Following the corrosion experiments, the oxide films of specimens were examined by SEM to examine the oxide existence. LiOH concentrations as high as 1 M (7000-ppm lithium) can lead to significantly increased electrochemical corrosion rate. It is suggested that the accelerated corrosion in concentrated solution is caused by the synergetic effect of LiOH, pH and porosity generation. In solutions containing 100 ppm of lithium, the presence of boron had an ameliorating effect on the corrosion rates of Zircaloy-2. Similar to acceleration of corrosion by lithium, the inhibition by boron is due to a combined effect of pH neutralizing and its participation in the corrosion process.

  16. Corrosion, haemocompatibility and bacterial adhesion behaviour of ...

    Indian Academy of Sciences (India)

    grade material is used to replace various parts of the body owing to its corrosion resistance, wear resistance and high hardness. However, after implantation, it .... thrombogenicity. The blood was drained from healthy. Figure 1. (a) GIXRD pattern of TiZrN coatings. (b) AFM images of uncoated 316L SS and (c) TiZrN coatings.

  17. Effect of fetal calf serum on the corrosion behaviour of magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hornberger, H., E-mail: helga.hornberger@ww.uni-erlangen.de [Laboratory for Biomechanics and Biomaterials, Hannover Medical School, Anna-von-Borries-Str. 1-7, D-30625 Hannover (Germany); Witte, F., E-mail: norbert.hort@gkss.de [Laboratory for Biomechanics and Biomaterials, Hannover Medical School, Anna-von-Borries-Str. 1-7, D-30625 Hannover (Germany); Department for Biotechnology Engineering, Ben-Gurion University of the Negev, Beer Sheva (Israel); Hort, N. [GKSS-Forschungszentrum Geesthacht GmbH, MagIC, Max-Planck-Str. 1, 21502 Geesthacht (Germany); Mueller, W.-D., E-mail: wolf-dieter.mueller@charite.de [Labor fuer zahnaerztliche Werkstoffkunde und Biomaterialforschung, Zentrum fuer Zahmedizin der Charite Universitaetsmedizin Berlin, Assmannshauserstr. 4-6, 14197 Berlin (Germany)

    2011-12-15

    The corrosion behaviour of WE43 magnesium alloys using the mini cell system was studied. Voltammetry and impedance spectroscopy were applied to study on the one hand the effect of microstructure of the working electrode and on the other hand the effect of proteins in the electrolyte. Two types of alloy samples were produced (i) by permanent mould casting and (ii) by gas atomization followed by extrusion. The results showed that the microstructure was strongly influenced by the production process. The extruded samples showed an improved homogeneity of phase distribution compared with cast samples as it was aimed for. Due to increased homogeneity it was expected to find higher corrosion resistance. However, the electrochemical results are contradictory and suggest an additional phase in the extruded microstructure. Using energy dispersive X-ray spectroscopy (EDX) the secondary magnesium rare earths (RE) phase of extruded samples showed differing composition than of cast samples as well as additional oxide phases. After the samples were electrochemically investigated in cell medium with and without fetal calf serum (FCS), an impact of FCS was detected in voltammetry due to the length of the polarisation curve. As the tip of the mini cell in contact with the working electrode is small, developing gases tend to spread on the working electrode and break the contact of liquid to the counter electrode; which results in disrupting the current flow. This effect was more pronounced when rising the voltage and was found reduced when using electrolytes with FCS. Impedance spectra were slightly deformed by FCS, seen as a kinetic effect but not as a basic differing corrosion reaction. The insight into the effects of FCS was provided by the mini cell system as this system enables to collect entire series of measurements. In contrast of two single measurements, those series reflected the slight difference caused by FCS. The focus of the electrochemical corrosion study was set on

  18. Corrosion and wear behaviour of multilayer pulse electrodeposited ...

    Indian Academy of Sciences (India)

    Corrosion and wear behaviour of multilayer pulse electrodeposited. Ni–Al2O3 nanocomposite coatings assisted with ultrasound. H MAJIDI, M ALIOFKHAZRAEI. ∗. , A KARIMZADEH and A SABOUR ROUHAGHDAM. Department of Materials Science, Faculty of Engineering, Tarbiat Modares University, Tehran 1411713116, ...

  19. Corrosion behaviour, microstructure and phase transitions of Zn ...

    Indian Academy of Sciences (India)

    Unknown

    ferent media, in particular, the corrosion behaviour of Zn-based alloys with respect to Al and Si contents is examined, and microstructure in acidic and TGA and phase transformations in ..... Soc. 132 1277. Boyer H E and Gall T L (eds) 1992 Metals handbook (Metals. Park, Ohio: American Society for Metals) pp 6.64, 11.6 and.

  20. Effects of crystalline growth on corrosion behaviour of ...

    Indian Academy of Sciences (India)

    The produced and annealed samples were characterized using X-ray diffraction, scanning elec- tron microscopy and transmission electron microscopy. The corrosion behaviours of coatings were examined in. NaCl 3/5% electrolyte by potentiostat analysis. The nanocrystalline NiAl coating with the average crystalline size of.

  1. Electrochemical Characterisation of Filiform Corrosion on Aluminium Rolled Products

    NARCIS (Netherlands)

    Huisert, M.

    2001-01-01

    When aluminium is protected by an organic coating a special form of corrosion can occur underneath the organic coating; filiform corrosion. This form of corrosion manifests itself as threadlike filaments under the coating, it causes local delamination of the coating and the coating cannot protect

  2. Electrochemical behaviour of superhydrophobic coating fabricated ...

    Indian Academy of Sciences (India)

    of Ecorr that confers a better corrosion resistance of the coated samples. Keywords. Al alloy; surface coating; superhydrophobicity; potentiodynamic polarization. 1. Introduction. Aluminium and its alloys exhibit high-specific strength, low density, excellent heat and electric conductivities and low- specific weight.1,2 These ...

  3. Carbon steel corrosion induced by sulphate-reducing bacteria in artificial seawater: electrochemical and morphological characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Paula, Mariana Silva de; Goncalves, Marcia Monteiro Machado; Rola, Monick Alves da Cruz; Maciel, Diana Jose; Senna, Lilian Ferreira de; Lago, Dalva Cristina Baptista do, E-mail: sdp.mari@gmail.com, E-mail: marciamg@uerj.br, E-mail: monickcruz@yahoo.com.br, E-mail: dijmaciel@gmail.com, E-mail: lsenna@uerj.br, E-mail: dalva@uerj.br [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Instituto de Quimica

    2016-10-15

    In this work, the corrosion behavior of carbon steel AISI 1020 was evaluated in artificial seawater in the presence of mixed sulfate-reducing bacteria (SRB) culture isolated from the rust of a pipeline. The corrosion evaluation was performed by electrochemical techniques (open circuit potential (E{sub ocp}), polarization curves and electrochemical impedance spectroscopy (EIS)), while the formation of a biofilm and corrosion products were observed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). The presence of SRB in the medium shifted the open circuit potential to more positive values and increased the corrosion rate of the steel. Electrochemical and morphological techniques confirmed the presence of a biofilm on the steel surface. EDS spectra data showed the presence of sulfur in the corrosion products. After removing the biofilm, localized corrosion was observed on the surface, confirming that localized corrosion had occurred. The biogenic sulfide may lead to the formation of galvanic cells and contributes to cathodic depolarization. (author)

  4. Electrochemical supercapacitor behaviour of functionalized candle ...

    Indian Academy of Sciences (India)

    ... and G (graphite) phase of carbon present in the candle soots. The electrochemical characterization was performed by cyclic voltammetry, galvanostatic charge/discharge test and impedance spectroscopy in 1MH2SO4 electrolyte. The functionalized candle soot electrode showed an enhanced specific capacitance value of ...

  5. Electrochemical Investigation of the Corrosion of Different Microstructural Phases of X65 Pipeline Steel under Saturated Carbon Dioxide Conditions

    Directory of Open Access Journals (Sweden)

    Yuanfeng Yang

    2015-05-01

    Full Text Available The aim of this research was to investigate the influence of metallurgy on the corrosion behaviour of separate weld zone (WZ and parent plate (PP regions of X65 pipeline steel in a solution of deionised water saturated with CO2, at two different temperatures (55 °C and 80 °C and at initial pH~4.0. In addition, a non-electrochemical immersion experiment was also performed at 80 °C in CO2, on a sample portion of X65 pipeline containing part of a weld section, together with adjacent heat affected zones (HAZ and parent material. Electrochemical impedance spectroscopy (EIS was used to evaluate the corrosion behaviour of the separate weld and parent plate samples. This study seeks to understand the significance of the different microstructures within the different zones of the welded X65 pipe in CO2 environments on corrosion performance; with particular attention given to the formation of surface scales; and their composition/significance. The results obtained from grazing incidence X-ray diffraction (GIXRD measurements suggest that, post immersion, the parent plate substrate is scale free, with only features arising from ferrite (α-Fe and cementite (Fe3C apparent. In contrast, at 80 °C, GIXRD from the weld zone substrate, and weld zone/heat affected zone of the non-electrochemical sample indicates the presence of siderite (FeCO3 and chukanovite (Fe2CO3(OH2 phases. Scanning Electron Microscopy (SEM on this surface confirmed the presence of characteristic discrete cube-shaped crystallites of siderite together with plate-like clusters of chukanovite.

  6. Corrosion behaviour of carbon steel in the Tournemire clay

    Energy Technology Data Exchange (ETDEWEB)

    Foct, F.; Dridi, W. [EDF R and D MMC, Site des Renardieres, 77818 Moret sur Loing Cedex (France); Cabrera, J.; Savoye, S. [IRSN/DEI/SARG, bat 76/2, BP 17, 92262 Fontenay-aux Roses (France)

    2004-07-01

    Carbon steels are possible materials for the fabrication of nuclear waste containers for long term geological disposal in argillaceous environments. Experimental studies of the corrosion behaviour of such materials has been conducted in various conditions. Concerning the numerous laboratory experiments, these conditions (water and clay mixture or compacted clay) mainly concern the bentonite clay that would be used for the engineered barrier. On the opposite, only few in-situ experiments has been conducted directly in the local clay of the repository site (such as Boom clay, etc.). In order to better estimate the corrosion behaviour of carbon steels in natural clay site conditions, an experimental study has been conducted jointly by EDF and IRSN in the argillaceous French site of Tournemire. In this study, A42 carbon steel specimens have been exposed in 3 different zones of the Tournemire clay formation. The first type of environmental conditions concerns a zone where the clay has not been affected by the excavation (EDZ) of the main tunnel neither by the main fracture zone of the clay formation. The second and third ones are located in the EDZ of the tunnel. In the second zone, an additional aerated water flows from the tunnel, whereas it does not in the third place. Some carbon steel specimens have been extracted after several years of exposure to these conditions. The average corrosion rate has been measured by the weight loss technique and the pitting corrosion depth has been evaluated under an optical microscope. Corrosion products have also been characterised by scanning electron microscopy and X-ray diffraction technique. Results are then discussed regarding the surrounding environmental conditions. Calculations of the oxygen transport from the tunnel through the clay and of the clay re-saturation can explain, in a first approach, the corrosion behaviour of the carbon steel in the different tested zones. (authors)

  7. Corrosion behaviour of carbon steel in the Tournemire clay

    International Nuclear Information System (INIS)

    Foct, F.; Dridi, W.; Cabrera, J.; Savoye, S.

    2004-01-01

    Carbon steels are possible materials for the fabrication of nuclear waste containers for long term geological disposal in argillaceous environments. Experimental studies of the corrosion behaviour of such materials has been conducted in various conditions. Concerning the numerous laboratory experiments, these conditions (water and clay mixture or compacted clay) mainly concern the bentonite clay that would be used for the engineered barrier. On the opposite, only few in-situ experiments has been conducted directly in the local clay of the repository site (such as Boom clay, etc.). In order to better estimate the corrosion behaviour of carbon steels in natural clay site conditions, an experimental study has been conducted jointly by EDF and IRSN in the argillaceous French site of Tournemire. In this study, A42 carbon steel specimens have been exposed in 3 different zones of the Tournemire clay formation. The first type of environmental conditions concerns a zone where the clay has not been affected by the excavation (EDZ) of the main tunnel neither by the main fracture zone of the clay formation. The second and third ones are located in the EDZ of the tunnel. In the second zone, an additional aerated water flows from the tunnel, whereas it does not in the third place. Some carbon steel specimens have been extracted after several years of exposure to these conditions. The average corrosion rate has been measured by the weight loss technique and the pitting corrosion depth has been evaluated under an optical microscope. Corrosion products have also been characterised by scanning electron microscopy and X-ray diffraction technique. Results are then discussed regarding the surrounding environmental conditions. Calculations of the oxygen transport from the tunnel through the clay and of the clay re-saturation can explain, in a first approach, the corrosion behaviour of the carbon steel in the different tested zones. (authors)

  8. Electrochemical behaviour of titanium coated stainless steel by r.f. sputtering in synthetic sweat solutions for electrode applications

    International Nuclear Information System (INIS)

    Fonseca, C.; Vaz, F.; Barbosa, M.A.

    2004-01-01

    The r.f. sputtering technique was used to deposit titanium thin films on stainless steel substrates, aiming at the application of the coated samples as skin contact materials for 'dry' active electrodes. In this work the electrochemical behaviour of the coated samples was investigated in synthetic sweat solutions and their performance was compared with that of uncoated stainless steel and bulk titanium. The characterisation of the samples was carried out by electrochemical techniques and scanning electron microscopy. The coated samples displayed corrosion resistance values in synthetic sweat solutions much higher than stainless steel samples and of the same order of the values measured for bulk titanium in the same conditions

  9. Electrochemical characterization of corrosion in materials of grounding systems, simulating conditions of synthetic soils with characteristics of local soils

    Science.gov (United States)

    Salas, Y.; Guerrero, L.; Vera-Monroy, S. P.; Blanco, J.; Jimenez, C.

    2017-12-01

    The integrity of structures buried in earthing becomes relevant when analysing maintenance and replacement costs of these systems, as the deterioration is mainly due to two factors, namely: the failures caused in the electrical systems, which are due to the system. Failure in earthing due to corrosion at the interface cause an alteration in the structure of the component material and generates an undesirable resistivity that cause malfunction in this type of protection systems. Two local soils were chosen that were categorized as sandy loam and clay loam type, whose chemical characteristics were simulated by means of an electrolyte corresponding to the amount of ions present determined by a soil characterization based on the CICE (effective cation exchange coefficient), which allows us to deduce the percentage of chloride and sulphate ions present for the different levels established in the experimental matrix. The interaction of these soils with grounding electrodes is a complex problem involving many factors to consider. In this study, the rates and corrosion currents of the different soils on two types of electrodes, one copper and the other AISI 304 stainless steel, were approximated by electrochemical techniques such as potentiodynamic curves and electrochemical impedance spectra. Considerably higher speeds were determined for copper-type electrodes when compared to those based on steel. However, from the Nyquist diagrams, it was noted that copper electrodes have better electrical performance than steel ones. The soil with the highest ionic activity turned out to be the sandy loam. The clay loam soil presents a tendency to water retention and this may be the reason for the different behaviour with respect to ionic mobility. The diffusion control in the steel seems to alter the ionic mobility because its corrosion rates proved to be very similar regardless of the type of soil chemistry. In general, corrosion rates fell since tenths of a millimetre every year to

  10. Evaluation of Electrochemical Behavior of Nopal Extract (Opuntia Ficus- Indica as Possible Corrosion Inhibitor

    Directory of Open Access Journals (Sweden)

    Araceli Mandujano-Ruíz

    2017-11-01

    Full Text Available Corrosion is one of the main problems of degradation in components, tooling, equipment and even in structural applications, examples of this are the carbon steels. In the present work, the capacity of corrosion inhibition of a biodegradable organic extract from the Nopal plant (Opuntia ficus-indica, for the protection of carbon steel type AISI 1018 was studied adding 50% v/v of the Nopal extract (EN in a solution of H2SO4 (0.6 mol.l-1. Polarization Resistance (LPR and Electrochemical Impedance Spectroscopy (EIS techniques were used for the electrochemical evaluation at room temperature for 24 h in order to obtain corrosion rates (Vcorr and inhibition efficiency (IE. Metallographic examination was also carried out to register the surface damage by corrosion. The results showed a reduction of the Vcorr with a maximum IE value of about 84% by adding the organic- liquid extracted from Nopal.

  11. Electrochemical behaviour of alkaline copper complexes

    Indian Academy of Sciences (India)

    3.2 Triethanolamine solutions. The electrochemical spectrum obtained in 10–2 M CuSO4 solutions containing 5 × 10–1 M. NaOH + 4 × 10–2 M TEA (figure 2) during the forward sweep shows a cathodic peak (I). Figure 2. Typical cyclic voltammogram in 0⋅01 M copper sulphate + 0⋅04 M. TEA + 1⋅0 M sodium hydroxide.

  12. The influence of pluronic P123 micelles on corrosion behaviour of steel in cement extract and bulk matrix properties of cement paste

    NARCIS (Netherlands)

    Koleva, D.A.; Denkova, A.G.; Hu, J.; van Breugel, K.

    2012-01-01

    The influence of Pluronic P123 (PEO20-PPO20-PEO70) micelles (of 10 nm size) on the corrosion behaviour of low carbon steel in cement extract (CE) was studied using electrochemical impedance spectroscopy (EIS) and potentio-dynamic polarisation (PDP). Additionally, mercury intrusion porosimetry (MIP)

  13. Electrochemical behaviour of graphene–poly (3,4-ethylene ...

    Indian Academy of Sciences (India)

    superior when compared to the polymer with a weight loss temperature of 350 ◦C for the composite and 250 ◦C for the polymer, respectively. The above electrochemical and thermal behaviours of the composite are correlated to the unique morphology of electrodeposited graphene that provides a conductive and high ...

  14. Electrochemical corrosion behavior of a Ti-35Nb alloy for medical prostheses

    International Nuclear Information System (INIS)

    Cremasco, Alessandra; Osorio, Wislei R.; Freire, Celia M.A.; Garcia, Amauri; Caram, Rubens

    2008-01-01

    Since the 1980s, the titanium alloys show attractive properties for biomedical applications where the most important factors are, firstly, biocompatibility, corrosion and mechanical resistances, low modulus of elasticity, very good strength to weight ratio, reasonable formability and osseointegration. The aim of this study was to investigate the effects of two different heat treatments; furnace cooling and water quenching, on the general electrochemical corrosion resistance of Ti-35 wt%Nb alloy samples immersed in a 0.9% NaCl (0.15 mol L -1 ) solution at 25 deg. C and neutral pH range. The samples were obtained using a non-consumable tungsten electrode furnace with a water-cooled copper hearth under argon atmosphere. The microstructural pattern was examined by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). In order to evaluate the electrochemical corrosion behavior of such Ti-Nb alloy samples, corrosion tests were performed by using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. Analyses of an equivalent circuit have also been used to provide quantitative support for the discussions and understanding of the corrosion behavior. It was found that water quenching provides a microstructural pattern consisting of an alpha-martensite acicular phase which decreases the material electrochemical performance due to the stress-induced martensitic transformation

  15. Electrochemical corrosion behavior of a Ti-35Nb alloy for medical prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Cremasco, Alessandra [Department of Materials Engineering, State University of Campinas, UNICAMP, P.O. Box 6122, 13083-970 Campinas, SP (Brazil); Osorio, Wislei R. [Department of Materials Engineering, State University of Campinas, UNICAMP, P.O. Box 6122, 13083-970 Campinas, SP (Brazil)], E-mail: wislei@fem.unicamp.br; Freire, Celia M.A.; Garcia, Amauri; Caram, Rubens [Department of Materials Engineering, State University of Campinas, UNICAMP, P.O. Box 6122, 13083-970 Campinas, SP (Brazil)

    2008-05-30

    Since the 1980s, the titanium alloys show attractive properties for biomedical applications where the most important factors are, firstly, biocompatibility, corrosion and mechanical resistances, low modulus of elasticity, very good strength to weight ratio, reasonable formability and osseointegration. The aim of this study was to investigate the effects of two different heat treatments; furnace cooling and water quenching, on the general electrochemical corrosion resistance of Ti-35 wt%Nb alloy samples immersed in a 0.9% NaCl (0.15 mol L{sup -1}) solution at 25 deg. C and neutral pH range. The samples were obtained using a non-consumable tungsten electrode furnace with a water-cooled copper hearth under argon atmosphere. The microstructural pattern was examined by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). In order to evaluate the electrochemical corrosion behavior of such Ti-Nb alloy samples, corrosion tests were performed by using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. Analyses of an equivalent circuit have also been used to provide quantitative support for the discussions and understanding of the corrosion behavior. It was found that water quenching provides a microstructural pattern consisting of an alpha-martensite acicular phase which decreases the material electrochemical performance due to the stress-induced martensitic transformation.

  16. Electrochemical behavior and localized corrosion of X65 steel in high salt concentration brines with CO2 saturated

    Science.gov (United States)

    Sun, Jianbo; Yang, Liying; Liu, Wei; Lu, Minxu

    2018-02-01

    The electrochemical characteristics and localized corrosion of X65 steel were investigated in CO2-saturated brines as a function of salt concentration employing electrochemical techniques and immersion tests. The results show that, as salt concentration increases, the corrosion mechanism changes from electrochemical steps control to the mixed control of mass transfer and electrochemical steps. The higher the salt concentration is, the more obvious the mass transfer control will be. The corrosion rate firstly increases and then decreases with salt content. There is a maximum corrosion rate somewhere between 60 and 120 g l‑1 salt content. The salting-out effect may play a crucial role in steel corrosion in CO2-bearing systems with higher salt concentrations. Chloride ions account for the decrease of the surface layer thickness and make them non-adherent, thereby promoting the initiation and development of localized corrosion at salt concentration above 120 g l‑1.

  17. Corrosion products behaviour under VVER primary coolant conditions

    International Nuclear Information System (INIS)

    Grygar, T.; Zmitko, M.

    2002-01-01

    The aim of this work was to collect data on thermodynamic stability of Cr, Fe, and Ni oxides, mechanisms of hydrothermal corrosion of stainless steels and to compare the real observation with the theory. We found that the electrochemical potential and pH in PWR and VVER are close to the thermodynamic boundary between two fields of stable spinel type oxides. The ways of degradation of the passivating layers due to changes in water chemistry were considered and PWR and VVER systems were found to be potentially endangered by reductive attack. In certain VVER systems the characteristics of the passivating layer on steels and also concentration of soluble corrosion products seem to be in contradiction with the theoretical expectations. (author)

  18. The corrosion behaviour of Zr3Al-based alloys

    International Nuclear Information System (INIS)

    Murphy, E.V.; Wieler, R.

    1977-07-01

    The corrosion resistance of several zirconium-aluminum alloys with aluminum contents ranging from 7.6 to 9.6 wt% was examined in 300 deg C and 325 deg C water, 350 deg C and 400 deg C steam and in air and wet CO 2 at 325 deg C and 400 deg C. In the transformed alloys there are three phases present, αZr, Zr 2 Al and Zr 3 Al of which the αZr phase is the least corrosion resistant. The most important factor controlling the corrosion behaviour of these alloys was found to be the size, distribution and amount of the αZr phase in the transformed alloys, which in turn was dependent upon the microstructural scale of the untransformed alloys

  19. Electrochemical corrosion behaviors of the X90 linepipe steel in NS4 solution

    Directory of Open Access Journals (Sweden)

    Jinheng Luo

    2016-10-01

    Full Text Available Oil and gas line pipes are laid underground and run through different areas in the laying process, so they will be subjected to different degrees of corrosion and even crack, leading to enormous casualties and economic losses. In order to guarantee the safe operation of line pipes, therefore, it is significant to investigate the electrochemical corrosion behaviors of pipe steel in a simulated soil environment. In this paper, the electrochemical corrosion behaviors of the base metals and welding materials of API 5L X90 steel longitudinally submerged arc welding pipes in near-neutral simulated soil solution (NS4 were studied by means of the electrochemical impedance spectroscopy (EIS and the potentiodynamic polarization testing technology. It is shown that the typical characteristic of anodic dissolution is presented but with no passivation phenomenon when X90 linepipe steel is put in NS4 solution. The base material is thermodynamically more stable than the seam weld material. The base material and seam weld samples were polarized under −850 mV polarization potential for different durations. It is demonstrated that with the proceeding of polarization, the polarization resistance and the corrosion resistance increase while the corrosion current density decreases. And the corrosion resistance of base material is better than that of seam weld material.

  20. Electrochemical Anti-corrosion System of Iron Tower Based on Solar Power Supply

    Directory of Open Access Journals (Sweden)

    Tian Tian

    2018-01-01

    Full Text Available Aiming at the serious problem of the corrosion of the transmission tower in the coastal area or in the harsh industrial area, a kind of electro-chemical anti-corrosion system based on solar power is designed. The system consists of a solar power module and an electrochemical anti-corrosion module: The solar power module consists of a solar panel, a photovoltaic controller, a accumulator and a constant potentiometer. The Electrochemical anti-corrosion modules include an anode block and an anode bed and reference electrode. The photovoltaic energy technology and forced current cathodic protection technology are used in the system, to achieve the effective protection of the tower anti-corrosion. Solar power supply to the nearest, solve the long-distance transmission loss and the high installation costs, form a simple structure, stable operation, low cost, clean and environmental protection, long service life of anti-corrosion system, with good economic efficiency and social benefits. It is of great significance to ensure the safe operation of the tower, maintain the normal operation of the power grid, and even promotes the optimization and upgrading of the industrial structure, save energy and reduces emissions, improve the safe and stable operation of the power system and the economic benefits, etc.

  1. Corrosion behaviour of hyper duplex stainless steel in various metallurgical conditions for sea water cooled condensers

    International Nuclear Information System (INIS)

    Singh, Umesh Pratap; Kain, Vivekanand; Chandra, Kamlesh

    2011-01-01

    The sea water cooled condensers have to resist severe corrosion as marine environment is the most corrosive natural environment. Copper alloys are being phased out due to difficulties in water chemistry control and Titanium base alloys are extremely expensive. Austenitic stainless steels (SS) remain prone to localized corrosion in marine environments hence not suitable. These heat exchangers operate at temperatures not exceeding 50 deg C and at very low pressures. The tubes of these heat exchangers are joined to the carbon steel tube sheets by roll expansion or by roll expansion followed by seam welding. These conditions are expected to affect the localized corrosion resistance of the tube in roll joined region due to cold working and in the tube-tube sheet welded joint due to thermal effects of welding. In this study, the localized corrosion behaviour of a Hyper Duplex Stainless Steel (HDSS) has been evaluated, and compared with other materials e.g. types 304L SS, 316L SS, Duplex SS 2205, Titanium grade - 2, and Al Brass. The evaluation is done in three metallurgical conditions (a) as received, (b) cold rolled and (c) welded condition in synthetic sea water at room temperature and at 50 deg C to assess the resistance to crevice, pitting and stress corrosion cracking using standard ASTM exposure and electrochemical techniques. The results provide comparative assessment of these alloys and show their susceptibility in the three metallurgical conditions as encountered in condensers. Hyper-duplex SS has been shown to be highly resistant in sea water for the condenser tubing application. (author)

  2. Electrochemical impedance spectroscopy (EIS) as a tool for measuring corrosion of polymer-coated fasteners used in treated wood

    Science.gov (United States)

    Samuel L. Zelinka; Lorraine Ortiz-Candelaria; Donald S. Stone; Douglas R. Rammer

    2009-01-01

    Currently, many of the polymer-coated fasteners on the market are designed for improved corrosion performance in treated wood; yet, there is no way to evaluate their corrosion performance. In this study, a common technique for measuring the corrosion performance of polymer-coated metals, electrochemical impedance spectroscopy (EIS), was used to evaluate commercial...

  3. Electrochemical testing of passivity state and corrosion resistance of supermartensitic stainless steels

    Directory of Open Access Journals (Sweden)

    S. Lasek

    2010-01-01

    Full Text Available On low interstitial - supermartensitic stainless steels (X1CrNiMo 12-5-1, X2CrNiMo 13-6-2, X1CrNiMo 12-6-2 the electrochemical potentiodynamic polarization tests were carried out and the passive state stability and localized corrosion resistance were compared and evaluated. The effect of quenching and tempering as well as the changes in microstructure on polarisation curves and corrosion properties at room temperature were established. Small differences in chemical composition of steels were also registered on their corrosion parameters changes and resistance.

  4. Electrochemical and crystallographic aspects of the corrosion of austenitic stainless steels in concentrated hot soda solutions

    International Nuclear Information System (INIS)

    Santarini, G.; Boos, J.Y.

    1976-01-01

    Some electrochemical and crystallographic aspects of stainless steel corrosion in concentrated hot soda are presented. Caustic cracking appears when the metallic surface presents an active behavior as immerged; the initial activity induces a selective dissolution of iron and chromium, and appearance of a pure nickel layer, which, by galvanic coupling, displaces the underlying surface potential towards a pseudo-passivity area; pseudo-passivity is due to the formation of a mixed oxide of the NaMO 2 type, which requires a revision of the thermodynamics bases of the alkaline corrosion interpretations. The crystallographic aspects of the mixed oxide growth enables a better understanding of the stress corrosion mechanisms [fr

  5. Electrochemical polarization measurements on pitting corrosion susceptibility of nickel-rich Alloy 825

    International Nuclear Information System (INIS)

    McCright, R.D.; Fleming, D.L.

    1991-10-01

    Alloy 825 contains approximately 40% Ni, 30% Fe, 20% Cr, 3.5% Mo, 2% Cu, and 1% Ti. Alloy 825 has a number of performance features that make it attractive as a candidate material for nuclear waste containers. However, under certain environmental conditions Alloy 825 is susceptible to localized forms of corrosion, and the focus of this paper is determination of those conditions. Electrochemical polarization was used to determine the critical potential for passive film breakdown, a process which leads to localized corrosion attack. Results indicated that quite high levels of chloride ion concentrations coupled with low pH are required to lower the critical potential to approach the corrosion potential

  6. Standard practice for calculation of corrosion rates and related information from electrochemical measurements

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1989-01-01

    1.1 This practice covers the providing of guidance in converting the results of electrochemical measurements to rates of uniform corrosion. Calculation methods for converting corrosion current density values to either mass loss rates or average penetration rates are given for most engineering alloys. In addition, some guidelines for converting polarization resistance values to corrosion rates are provided. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

  7. Shadow corrosion phenomenon. An out-of-pile study on electrochemical effects

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Nadine

    2017-04-28

    The focus of the present thesis was the study of the enhanced corrosion phenomenon named ''Shadow Corrosion''. Within the context of researching based on the corrosion mechanism as well as the influencing parameters and driving forces, which cause or even intensify the corrosion, a variety of electrochemical characterization and surface analysis techniques were used. The first part of this thesis gives a short introduction with the definition of the term Shadow Corrosion and of the specific type called ''Enhanced Spacer Shadow Corrosion'' (ESSC). This is followed by a description of the involved materials being Zircaloy and Inconel 718. Chapter 2 introduces the background knowledge including fundamentals about environ-mental conditions under which Shadow Corrosion occurs as well as the oxidation behavior of Zircaloy and Inconel 718. Furthermore, the state of the art about the Shadow Corrosion mechanism is presented and a description of the influencing effects on the enhanced corrosion phenomenon, like galvanic corrosion, water radiolysis, and photo-effect, is given. Further information and parameters on the part of AREVA GmbH concerning water impurities and a used coating layer on Inconel 718 are listed, which are of interest for the issue concerning the phenomenon Shadow Corrosion. The last part of this chapter contains the experimental conditions and parameters for the laboratory experiments with focus on water chemistry, specimen geometry, and UV-light exposure for photoexcitation and water radiolysis. Three different working hypotheses of this thesis are described in chapter 3. One hypothesis regarding the Shadow Corrosion Phenomenon is based on a galvanic corrosion mechanism between Zircaloy and Inconel 718. In addition, it is supposed that the galvanic corrosion could be influenced by the deposition of silver on Zircaloy and Inconel 718 in the form of an increased galvanic current. A further assumption is that the

  8. In vitro corrosion behaviour of Ti-Nb-Sn shape memory alloys in Ringer's physiological solution.

    Science.gov (United States)

    Rosalbino, F; Macciò, D; Scavino, G; Saccone, A

    2012-04-01

    The nearly equiatomic Ni-Ti alloy (Nitinol) has been widely employed in the medical and dental fields owing to its shape memory or superelastic properties. The main concern about the use of this alloy derives form the fact that it contains a large amount of nickel (55% by mass), which is suspected responsible for allergic, toxic and carcinogenic reactions. In this work, the in vitro corrosion behavior of two Ti-Nb-Sn shape memory alloys, Ti-16Nb-5Sn and Ti-18Nb-4Sn (mass%) has been investigated and compared with that of Nitinol. The in vitro corrosion resistance was assessed in naturally aerated Ringer's physiological solution at 37°C by corrosion potential and electrochemical impedance spectroscopy (EIS) measurements as a function of exposure time, and potentiodynamic polarization curves. Corrosion potential values indicated that both Ni-Ti and Ti-Nb-Sn alloys undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the aggressive environment. It also indicated that the tendency for the formation of a spontaneous oxide is greater for the Ti-18Nb-5Sn alloy. Significantly low anodic current density values were obtained from the polarization curves, indicating a typical passive behaviour for all investigated alloys, but Nitinol exhibited breakdown of passivity at potentials above approximately 450 mV(SCE), suggesting lower corrosion protection characteristics of its oxide film compared to the Ti-Nb-Sn alloys. EIS studies showed high impedance values for all samples, increasing with exposure time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The obtained EIS spectra were analyzed using an equivalent electrical circuit representing a duplex structure oxide film, composed by an outer and porous layer (low resistance), and an inner barrier layer (high resistance) mainly responsible for the alloys corrosion resistance. The resistance of passive film present on the metals' surface

  9. Combined geochemical and electrochemical methodology to quantify corrosion of carbon steel by bacterial activity

    International Nuclear Information System (INIS)

    Schutz, Marta K.; Moreira, Rebeca; Tribollet, Bernard; Vivier, Vincent; Bildstein, Olivier; Lartigue, Jean-Eric; Libert, Marie; Schlegel, Michel L.

    2014-01-01

    The availability of respiratory substrates, such as H 2 and Fe(II,III) solid corrosion products within nuclear waste repository, will sustain the activities of hydrogen-oxidizing bacteria (HOB) and iron-reducing bacteria (IRB). This may have a direct effect on the rate of carbon steel corrosion. This study investigates the effects of Shewanella oneidensis (an HOB and IRB model organism) on the corrosion rate by looking at carbon steel dissolution in the presence of H 2 as the sole electron donor. Bacterial effect is evaluated by means of geochemical and electrochemical techniques. Both showed that the corrosion rate is enhanced by a factor of 2-3 in the presence of bacteria. The geochemical experiments indicated that the composition and crystallinity of the solid corrosion products (magnetite and vivianite) are modified by bacteria. Moreover, the electrochemical experiments evidenced that the bacterial activity can be stimulated when H 2 is generated in a small confinement volume. In this case, a higher corrosion rate and mineralization (vivianite) on the carbon steel surface were observed. The results suggest that the mechanism likely to influence the corrosion rate is the bioreduction of Fe(III) from magnetite coupled to the H 2 oxidation. (authors)

  10. Electrochemical Corrosion Characteristics of Arc-Ion-Plated AlTiN Coating for Marine Application.

    Science.gov (United States)

    Lee, Jung-Hyung; Kim, MyoungJun; Kim, Seong-Jong

    2016-02-01

    In this study, aluminum titanium nitride (AlTiN) coating was deposited by arc ion plating onto mirror finish STS 304 plate. The surface and cross-section of the coating was characterized by SEM and EDX analysis. Several electrochemical corrosion experiments were performed including rest potential measurement, potentiodynamic polarization experiment and Tafel analysis. The result of the experiments indicated that the AlTiN coating presented lower corrosion current density than the substrate material (STS 304) under uniform corrosion environment. It was also observed that AlTiN coating may have a risk of being attacked by localized corrosion attack such as pitting when pores or micro/nano particles in the coating are exposed to chloride ion containing corrosion environment, especially marine environment.

  11. Corrosion behaviour of nickel during anodic polarization in chloride solution

    International Nuclear Information System (INIS)

    Memon, S.A.; Isani, A.A.; Memon, A.N.

    1998-01-01

    This research presents the effect of oxygen and nitrogen on the corrosion behaviour of nickel in the chloride solution, at the steady state polarized and unpolarized potentials. The additives were selected from those, which are used for bright nickel plating. It was observed that the agitation of electrolyte in a particular pH-(Cl)' range increase the potentials in comparison of the potentials to the un-agitated electrolytes. (author)

  12. Long term corrosion of iron and non alloy or low alloy steels in clay soils. Physico-chemical characterisation and electrochemical study of archaeological analogues

    International Nuclear Information System (INIS)

    Pons, Emmanuelle

    2002-01-01

    Archaeological objects of Gallo-Roman and Merovingian time, and from a battlefield of World War 1, were studied to better understand long term corrosion phenomena of iron in clay soils. This study is part of the French national program about nuclear waste deep repository, conducted by the ANDRA (French national Agency for Radioactive Waste Management). Iron archaeological analogues make a valuable contribution to the specifying of containers for long lived and high level wastes (HLWs), because they provide access to the considered time scale. The experimental issue is divided into two major parts: - a physico-chemical characterisation of corrosion products, by Raman spectroscopy; - an electrochemical study of the behaviour of the different corrosion layers. Although the metallic material is different between ancient artefacts (ferrite) and 1914-1918 remains (hypo-eutectoid steels), the same stable phases are identified in their corrosion products: mainly iron oxides and oxi-hydroxides. From a macroscopic point of view, these products are staggered into two layers: an internal one, and an external one, which contains soil markers. Under the microscope, a complex composite structure appears. Goethite a-FeOOH, which was identified on each object, is frequently in contact with the metal core. The average corrosion rate in the burial environment, deduced from the layers thickness, highlights a significant slowdown of corrosion after the first burial time, about one century. The electrochemical study showed the predominant role of transport phenomena in the pores of corrosion layers. The behaviour of the metal - internal layer system is well explained by a model of porous electrode (De Levie theory). Despite its porosity, the internal layer is protective, as it leads to a significant decrease of the corrosion rate (about ten time). (author) [fr

  13. Development of new corrosion inhibitor tested on mild steel supported by electrochemical study

    Directory of Open Access Journals (Sweden)

    Hussein Jwad Habeeb

    2018-03-01

    Full Text Available Mild steel is a metal which is commonly used in industrials and manufacturing of equipment for most industries round the world. It is cheaper cost compared with the other metals and its durable, hard and easy-to-wear physical properties make it a major choice in the manufacture of equipment parts. The main problem through the uses of mild steel in industry is its resistance against corrosion, especially in acidic solutions. This case led to raise the cost of maintenance of equipment that used mild steel and as a result increased costs for the company. Organic corrosive inhibitors that also act as green chemicals, 4-hydroxybenzylideneaminomethyl-5-ethyl-1,3,4-thiadiazol have been synthesized. This inhibitor is tested as corrosion inhibitor on a mild steel sample MS in 1 M hydrochloric acid solution (HCl using electrochemical measurements test includes PD (Potentiodynamic, EIS (Electrochemical impedance spectroscopy, OCP (Open circuit potential and EFM (electrochemical frequency modulation. The obtained results indicate that 4-hydroxybenzylideneaminomethyl-5-ethyl-1,3,4-thiadiazol acts as a good corrosion inhibitor for mild steel sample in HCl solution with efficiency above 90%. Changes in the impedance parameters postulated adsorption on the mild steel specimens' surfaces of, which it going to the formation of protective coating layer. It also shows that 4-hydroxybenzylideneaminomethyl-5-ethyl-1,3,4-thiadiazol corrosion inhibitors are effective in helping to reduce and slow down the corrosion process that occurs on mild steel surface in hydrochloric acid solution. Increase of corrosion inhibitor concentration provides a protective layer of mild steel. However, this protective layer becomes weak when the temperature of the solution increases. Keywords: Hydroxybenzylideneaminomethy, Potentiodynamic, Electrochemical frequency modulation, Impedance

  14. Electrochemical and surface studies of some Porphines as corrosion inhibitor for J55 steel in sweet corrosion environment

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ambrish, E-mail: ambrish.16752@ipu.co.in [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University), Chengdu, Sichuan 610500 (China); Department of Chemistry, LFTS, Lovely Professional University, Phagwara, Punjab 144402 (India); Lin, Yuanhua, E-mail: yhlin28@163.com [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University), Chengdu, Sichuan 610500 (China); Ansari, K.R.; Quraishi, M.A. [Department of Applied Chemistry, Indian Institute of Technology, Banaras Hindu University, Varanasi, U.P. (India); Ebenso, Eno. E. [Department of Chemistry, School of Mathematical & Physical Sciences, North-West University(Mafikeng Campus), Private Bag X2046, Mmabatho 2735 (South Africa); Chen, Songsong; Liu, Wanying [CNPC Key Lab for Tubular Goods Engineering (Southwest Petroleum University), Chengdu, Sichuan 610500 (China)

    2015-12-30

    Graphical abstract: Corrosion inhibition of J55 steel in 3.5 wt.% NaCl solution saturated with CO2 by the three Porphines 5,10,15,20-Tetra(4-pyridyl)-21H,23H-porphine (P1), 5,10,15,20-Tetraphenyl-21H,23H-porphine (P2), 5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine (P3), electrochemical impedance spectroscopy (EIS), contact angle measurement, scanning electrochemical microscopy (SECM), and atomic force microscopy (AFM). - Highlights: • J55 steel protection in 3.5% NaCl solution saturated with CO2 by Porphines. • Weight loss and impedance results are in good agreement. • The adsorption of Porphines obeys the Langmuir adsorption isotherm. • Scanning electrochemical microscopy is used to discuss the insulated and conductive surface. • Examination of surface morphology by AFM. - Abstract: Corrosion inhibition of J55 steel in 3.5 wt.% NaCl solution saturated with CO{sub 2} by the three Porphines 5,10,15,20-Tetra(4-pyridyl)-21H,23H-porphine (P1), 5,10,15,20-Tetraphenyl-21H,23H-porphine (P2), 5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine (P3), electrochemical impedance spectroscopy (EIS), Contact angle measurement, scanning electrochemical microscopy (SECM), and atomic force microscopy (AFM). Adsorption of such Porphines on the J55 steel surface obeyed to the Langmuir adsorption isotherm. Atomic force microscopy (AFM), SECM, and Contact angle results confirm the formation of inhibitor film on J55 steel surface thereby mitigating corrosion.

  15. Corrosion behaviour of austenitic stainless steel as a function of methanol concentration for direct methanol fuel cell bipolar plate

    Science.gov (United States)

    Wang, Lixia; Kang, Bin; Gao, Na; Du, Xiao; Jia, Linan; Sun, Juncai

    2014-05-01

    The corrosion behaviour of an AISI 304 stainless steel (304 SS) is investigated in aqueous acid methanol solutions (0.5 M H2SO4 + 2 ppm HF + x M CH3OH, x = 0, 1, 5, 10 and 20) at 50 °C to simulate the varied anodic operating conditions of direct methanol fuel cells. Electrochemical measurements including potentiodynamic polarisation, potentiostatic polarisation and electrochemical impedance spectroscopy tests, are employed to analyse the corrosion behaviour. The results reveal that the corrosion resistance of 304 SS is enhanced in solutions with higher methanol content. Scanning electron microscopy and inductively coupled plasma atomic emission spectrometry data indicate that the surface corrosion on 304 SS is alleviated when the methanol concentration is increased. According to the X-ray photoelectron spectroscopy and Mott-Schottky analyses, the passive films formed on the 304 SS after potentiostatic tests in all the test solutions are composed of a duplex electronic structure with an external n-type semiconductor layer and an internal p-type semiconductor layer. Further analyses of the surface conductivity conducted by measuring the interfacial contact resistance between the 304 SS and carbon paper reveal that the passive film formed in the solution with higher methanol content exhibits lower conductivity.

  16. INVESTIGATION OF THE ELECTROCHEMICAL BEHAVIOUR OF ...

    African Journals Online (AJOL)

    a

    electrodes containing high amount of Pt towards methanol oxidation is due to the bifunctional behaviour of the electrodes. ... hydroxyl radicals and active chlorine species to destroy refractory organic waste into carbon dioxide [9-12]. But, the oxidation of organic compounds occurs in the domain of water decomposition, i.e. ...

  17. INVESTIGATION OF THE ELECTROCHEMICAL BEHAVIOUR OF ...

    African Journals Online (AJOL)

    a

    containing low quantity of Pt, the surface of the coating is essentially composed of IrO2 and methanol oxidation occurs in the domain of water ... electrodes containing high amount of Pt towards methanol oxidation is due to the bifunctional behaviour of the electrodes. ..... fuel cell application and for the wastewater treatment.

  18. Flow-induced corrosion of absorbable magnesium alloy: In-situ and real-time electrochemical study

    International Nuclear Information System (INIS)

    Wang, Juan; Jang, Yongseok; Wan, Guojiang; Giridharan, Venkataraman; Song, Guang-Ling; Xu, Zhigang; Koo, Youngmi; Qi, Pengkai; Sankar, Jagannathan; Huang, Nan; Yun, Yeoheung

    2016-01-01

    Highlights: • An in-situ and real-time electrochemical monitoring of flow-induced corrosion of Mg alloy is designed in a vascular bioreactor. • Effect of hydrodynamics on corrosion kinetics, types, rates and products is analyzed. • Flow accelerates mass and electron transfer, leading to an increase in uniform and localized corrosions. • Flow increases not only the thickness of uniform corrosion product layer, but the removal rate of localized corrosion products. • Electrochemical impedance spectroscopy and linear polarization-measured polarization resistances provide a consistent correlation to corrosion rate calculated by computed tomography. - Abstract: An in-situ and real-time electrochemical study in a vascular bioreactor was designed to analyze corrosion mechanism of magnesium alloy (MgZnCa) under mimetic hydrodynamic conditions. Effect of hydrodynamics on corrosion kinetics, types, rates and products was analyzed. Flow-induced shear stress (FISS) accelerated mass and electron transfer, leading to an increase in uniform and localized corrosions. FISS increased the thickness of uniform corrosion layer, but filiform corrosion decreased this layer resistance at high FISS conditions. FISS also increased the removal rate of localized corrosion products. Impedance-estimated and linear polarization-measured polarization resistances provided a consistent correlation to corrosion rate calculated by computed tomography.

  19. Electrochemical evaluation for corrosion resistance of bacterial exopolysaccharides on low carbon steel

    Science.gov (United States)

    Corrosion is a global issue that affects safety and economics. There is an increasing demand for bio-based polymers for industrial applications and production of polymers by microorganisms is especially attractive. This work reports on the electrochemical and physical properties of 29 strains or fr...

  20. Novel time–frequency characterization of electrochemical noise data in corrosion studies using Hilbert spectra

    NARCIS (Netherlands)

    Homborg, A.M.; Westing, E.P.M.; Tinga, Tiedo; Zhang, X; Oonincx, P.J.; Ferrari, G.M.; de Wit, J.H.W.; Mol, J.M.C.

    2013-01-01

    Hilbert spectra, calculated with the Hilbert–Huang transform, are presented here as an analysis technique for the characterization of electrochemical noise data in corrosion studies. A highly detailed decomposition of the original current and potential data is provided in time and frequency

  1. A Technical Review of Electrochemical Techniques Applied to Microbiologically Influenced Corrosion

    Science.gov (United States)

    1991-01-01

    in the literature for the study of MIC phenomena. Videla65 has used this technique in a study of the action of Cladosporium resinae growth on the...ROSALES, Corrosion 44, 638 (1988). 65. H. A. VIDs, The action of Clado.sporiuo resinae growth on the electrochemical behavior of aluminum. Proc. bit. Conf

  2. Study of anti corrosive behaviour on A I 6061 samples covered with Ni-P alloys obtained by autocatalytic method

    International Nuclear Information System (INIS)

    Castro, M. E; Barbero, J. A; Bubach, E

    2006-01-01

    There are many ways to keep safe an industrial material from corrosion attack.One is covering the piece with a layer of another material which corrosion resistance is higher to the one of the element to protect.The anticorrosion protection mechanism is achieved by the formation of a physical pore less barrier without any defects.This avoid the arrival of those agents from environment responsible of electrochemical attack.In this paper, corrosion resistance of metallic coatings over nuclear usage aluminum samples is analyzed.Our interest is aimed on nickel I phosphorous alloy coatings (Ni I P) obtained by electroless method (autocatalytic) over Al 6061 alloy samples.A comparative study is carried on with different phosphorous contents but always under 12 %.This job is completed with other nickel coating, Vitro vac 0080 (with no phosphorous content) in order to compare structures and anti corrosive properties.Besides, the comparison between mentioned materials and aluminum samples is made.The study is carried on using superficial characterization of each sample with or without coating through a series of complementary techniques such as chemical, electrochemical (linear sweep voltammetry, cyclic voltammetry, polarization resistance determination) and physical (scanning electronic microscopy, hardness determination) techniques.Finally, variable correlation is made as a function of the phosphorous content in the samples used in the experiences.The coating structure obtained is amorphous.It presents no pore or failure and its hardness shows important values.The electrochemical analysis allows to check that anti corrosive protection capacity of Ni-P alloy increases with the phosphorous content in the coat. Al 6061 by itself demonstrate an electrochemically bad behaviour.Substrate I coating adherence is very good [es

  3. Electrochemical corrosion response of a low carbon heat treated steel in a NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Osorio, W.R.; Peixoto, L.C.; Garcia, L.R.; Garcia, A. [Department of Materials Engineering, State University of Campinas, SP (Brazil)

    2009-10-15

    Dual-phase (DP) steels are produced from a specific heat treatment procedure and have recently emerged as a potential class of engineering materials for a number of structural and automobile applications. Such steels have high strength-to-weight ratio and reasonable formability. The present study aims to investigate the effects of four different and conventional heat treatments (i.e., hot rolling, normalizing, annealing, and intercritical annealing) on the resulting microstructural patterns and on the electrochemical corrosion behavior. Electrochemical impedance spectroscopy (EIS) and Tafel plots were carried out on heat treated steel samples in a 0.5 M NaCl solution at 25 C with neutral pH. An equivalent circuit analysis was also used to provide quantitative support for the discussions. The normalizing and the annealing heat treatments have provided the highest and the lowest corrosion resistances, respectively. The intercritical annealing and as-received (hot rolled) low carbon steel samples have shown similar corrosion behavior. Although a deleterious effect on the corrosion resistance has been verified for DP steel due to the residual stress from the martensite formation, it combines good mechanical properties with intermediate electrochemical corrosion resistance. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  4. Electrochemical Corrosion Behavior of Near-Nano and Nanostructured WC-Co Cemented Carbides

    Directory of Open Access Journals (Sweden)

    Željko Alar

    2017-02-01

    Full Text Available In this paper, the electrochemical corrosion resistance of near-nano and nanostructured WC-Co cemented carbides was investigated. WC powders with an average grain size dBET in the range from 95 nm to 150 nm and with an addition of vanadium carbide (VC and chromium carbide Cr3C2 as grain growth inhibitors were used as starting powders. The mixtures with 6 wt. % and 9 wt. % Co were consolidated by two different processes; sintering in hydrogen atmosphere and the sinter-HIP process. WC-Co samples were researched by direct current and alternating current techniques in the solution of 3.5% NaCl at room temperature. Corrosion parameters such as corrosion potential (Ecorr, corrosion current density (jcorr and polarization resistance (Rp were determined by electrochemical techniques. From the conducted research, it was found that the consolidation processes and microstructural characteristics—grain growth inhibitors, grain size of the starting WC powders and η-phase—influenced the electrochemical corrosion resistance. η-phase enhanced the formation of a passive layer on the samples’ surfaces, thereby reducing the tendency of the sample dissolution and increasing the stability of oxides forming therewith a passive layer on the sample surface.

  5. Effect of cold deformation on the electrochemical behaviour of 304L stainless steel in contaminated sulfuric acid environment

    Science.gov (United States)

    Luo, Hong; Su, Huaizhi; Ying, Guobing; Dong, Chaofang; Li, Xiaogang

    2017-12-01

    The effect of cold deformation on the microstructure and electrochemical corrosion behaviour of 304L stainless steel in contaminated sulfuric acid solutions (simulated proton exchange membrane fuel cells environments) were evaluated using electron backscatter diffraction analyses, electrochemical measurements, and surface analyses. The internal microstructure,including the grain sizes, angles of the grain boundaries, low coincidence site lattice boundaries, and phase transformations, was changed due to the cold deformation. No noticeable modifications of the pitting corrosion potential were observed during the various deformations, except for a slight enhancement in the passive current density with an increase in the deformation. The CrO3 and metal Ni species in the passive film were investigated after deformation. After heavy deformation (greater than 60%), nickel oxides were detected. Moreover, the Cr/Fe and O2-/OH- ratios in the passive film were higher before deformation, and they decreased with an increase in the deformation level.

  6. Electrochemical passivation behaviour of nanocrystalline Fe80Si20 ...

    Indian Academy of Sciences (India)

    The passivation behaviour of binary cast Fe–Si alloys tested in phthalate buffer solution has shown that low Si alloys do not form a thick SiO2 layer and only iron oxide layer forms. In case of Si-rich alloys, formation of a stable SiO2 layer leads to improved corrosion resistance (Wolff et al 2001). The stability of the passive ...

  7. Development of Zn-SiC composite coatings: Electrochemical corrosion studies

    Directory of Open Access Journals (Sweden)

    Mudigere Krishnegowda Punith Kumar

    2015-03-01

    Full Text Available The Zn-SiC composite coatings were fabricated by using sulphate plating bath dispersed with 1, 2 and 3 g L-1 of 64.28 nm SiC nanoparticles. Appreciable influence on morphology and microstructure was observed in scanning electron microscopy, X-ray diffraction spectroscopy and texture co-efficient calculations for SiC incorporated zinc coatings. The electrochemical corrosion behavior of zinc and Zn-SiC composite coatings was studied by potentiodynamic polarization and electrochemical impedance analysis. Significant reduction in corrosion current and corrosion rate with increased charge transfer resistance was noticed for composite coatings. The SiC incorporated zinc coatings shown improved micro-hardness property to pure zinc coating. The properties of Zn-SiC composite coatings were compared with that of pure zinc coating.

  8. Investigation of the effect of phosphorus, sulfur and molybdenum additions on the corrosion-electrochemical behaviour of steel-Kh20N20 in acid media in the transpassivation field

    International Nuclear Information System (INIS)

    Kasparova, O.V.; Bogolyubskij, S.D.; Kolotyrkin, Ya.M.; Ul'yanin, E.A.; Vasyukov, A.B.; Yudina, N.S.; Kostromina, S.V.

    1979-01-01

    The separate effect has been studied of phosphorus additions (0.002-0.097%), sulfur (0.005-0.014%) and molybdenum (0.005-0.56%) on the tendency of highly pure austenite stainless steel-Kh20N20 to intercrystalline corrosion (ICC) in 1 N. H 2 SO 4 (t=40 deg) and in the boiling solution of 27% HNO 3 +40 g/l Cr 6+ in transpassive region. After various conditions of heat treatment of steel samples investigated the electron microscopic analysis of their structure has been performed. It is shown that in a hardened steel phosphorus additions considerably decrease the corrosion resistance of grain boundaries in both studied media and that sulfur and molybdenum additions exert a harmful slight effect on steel susceptibility to ICC in nitric acid solution and practically do not affect it in sulfuric acid. The effect of additions on Kh20N20 steel tendency to ICC is presumably to be explained by their segregation in intercrystalline zones

  9. Membrane-Coated Electrochemical Sensor for Corrosion Monitoring in Natural Gas Pipelines

    Directory of Open Access Journals (Sweden)

    J. Beck

    2017-07-01

    Full Text Available Electrochemical sensors can be used for a wide range of online in- situ process monitoring applications. However, the lack of a consistent electrolyte layer has previously limited electrochemical monitoring in gas and supercritical fluid streams. A solid state sensor is being designed that uses an ion conducting membrane to perform conductivity and corrosion measurements in natural gas pipelines up to 1000 psi. Initial results show that membrane conductivity measurements can be correlated directly to water content down to dew points of 1°C with good linearity. Corrosion monitoring can also be performed using methods such as linear polarization resistance and electrochemical impedance spectroscopy (EIS, though care must be taken in the electrode design to minimize deviation between sensors.

  10. Corrosion behaviour of TiN and ZrN in the environment containing fluoride ions

    Energy Technology Data Exchange (ETDEWEB)

    Joska, Ludek; Fojt, Jaroslav; Hradilova, Monika [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Hnilica, Frantisek [UJP, Prague (Czech Republic); Cvrcek, Ladislav, E-mail: joskal@vscht.c [HVM Plasma, Prague (Czech Republic)

    2010-10-01

    Nowadays, a wide range of materials for human implants is used. To reach the required properties of implants, coatings are applied in some cases. This contribution is focused on the corrosion properties of TiN and ZrN layers on cp-titanium (commercially pure titanium) under environment modelling conditions in an oral cavity. Measurements were done in artificial saliva and a physiological solution unbuffered and buffered to a pH value of 4.2 with the addition of fluoride ions up to 4000 ppm. Standard corrosion electrochemical techniques were applied. Both types of layers were stable in both model saliva and physiological solution with non-adjusted pH. The decrease in pH to 4.2 resulted in a minor decrease of corrosion resistance in all cases, but polarization resistance was still in the order of 10{sup 5} {Omega} cm{sup 2}. An important change in a specimens' behaviour was noticed in the presence of fluoride ions. TiN was stable in the highest concentration of fluorides used. The ZrN layers were destabilized in an environment containing a few hundred ppm of fluoride ions. As for TiN, the decisive factor is the influence of porosity; the corrosion resistance of ZrN is limited. From the corrosion point of view, the application of the TiN-based barrier layers in dental implantology is more advisable than the use of ZrN, provided that the application of a barrier is inevitable.

  11. ELECTROCHEMICAL STUDIES OF URANIUM METAL CORROSION MECHANISM AND KINETICS IN WATER

    International Nuclear Information System (INIS)

    Boudanova, Natalya; Maslennikov, Alexander; Peretroukhine, Vladimir F.; Delegard, Calvin H.

    2006-01-01

    During long-term underwater storage of low burn-up uranium metal fuel, a corrosion product sludge forms containing uranium metal grains, uranium dioxide, uranates and, in some cases, uranium peroxide. Literature data on the corrosion of non-irradiated uranium metal and its alloys do not allow unequivocal prediction of the paragenesis of irradiated uranium in water. The goal of the present work conducted under the program 'CORROSION OF IRRADIATED URANIUM ALLOYS FUEL IN WATER' is to study the corrosion of uranium and uranium alloys and the paragenesis of the corrosion products during long-term underwater storage of uranium alloy fuel irradiated at the Hanford Site. The elucidation of the physico-chemical nature of the corrosion of irradiated uranium alloys in comparison with non-irradiated uranium metal and its alloys is one of the most important aspects of this work. Electrochemical methods are being used to study uranium metal corrosion mechanism and kinetics. The present part of work aims to examine and revise, where appropriate, the understanding of uranium metal corrosion mechanism and kinetics in water

  12. Release Properties and Electrochemical Characterization of Encapsulated Corrosion Inhibitors for Environmentally Friendly Smart Coatings

    Science.gov (United States)

    Pearman, B. P.; Calle, L. M.; Zhang, X.; Li, W.; Buhrow, J. W.; Johnsey, M. N.; Montgomery, E. L.; Fitzpatrick, L.; Surma, J. M.

    2015-01-01

    The NASA Kennedy Space Center's Corrosion Technology Lab at the Kennedy Space Center in Florida, U.S.A. has been developing multifunctional smart coatings based on the microencapsulation of environmentally friendly corrosion indicators, inhibitors and self-healing agents. This allows for the incorporation of autonomous corrosion control functionalities, such as corrosion detection and inhibition as well as the self-healing of mechanical damage, into coatings. This paper presents technical details on the characterization of inhibitor-containing particles and their corrosion inhibitive effects using electrochemical and mass loss methods. Three organic environmentally friendly corrosion inhibitors were encapsulated in organic microparticles that are compatible with desired coatings. The total inhibitor content and the release of one of the inhibitors from the microparticles in basic solution was measured. Particles with inhibitor contents of up 60 wt% were synthesized. Fast release, for immediate corrosion protection, as well as long-term release for continued protection, was observed. The inhibition efficacy of the inhibitors, both as the pure materials and in microparticles, on carbon steel was evaluated. Polarization curves and mass loss measurements showed that, in the case of 2MBT, its corrosion inhibition effectiveness was greater when it was delivered from microparticles.

  13. Corrosion behaviour and deposition of crud on Zr-alloys

    International Nuclear Information System (INIS)

    Maroto, A.J.G.; Bordoni, R.; Olmedo, A.M.; Villegas, M.; Chocron, M.; Szpunar, J.

    1999-01-01

    The results from the long term corrosion surveillance of Zr-alloys samples located out of pile in the primary heat transfer system of a PHWR with standard water chemistry show that, up to 3400 days, the mean value of the oxide thickness obtained for Zr-2.5Nb and Zry-4 samples exposed at 305 deg. C is in good agreement with the values reported in the literature. The amount of crud deposited on the corrosion samples was calculated at every inspection of the long term surveillance programme. The corrosion behaviour of these alloys is also studied in static autoclaves with lithiated heavy water. The effect on Zr-alloys of a change in chemistry resulting from the degradation of mixed resins in the primary heat transfer system was investigated in additional tests in static autoclaves up to 120 days at 400 deg. C comparing the results with those from the corrosion samples inserted in the autoclave facilities of the plant. (author)

  14. Electrochemical behaviour and surface conductivity of niobium carbide-modified austenitic stainless steel bipolar plate

    Science.gov (United States)

    Wang, Lixia; Sun, Juncai; Kang, Bin; Li, Song; Ji, Shijun; Wen, Zhongsheng; Wang, Xiaochun

    2014-01-01

    A niobium carbide diffusion layer with a cubic NbC phase surface layer (∼6 μm) and a Nb and C diffusion subsurface layer (∼1 μm) is fabricated on the surface of AISI 304 stainless steel (304 SS) bipolar plate in a proton exchange membrane fuel cell (PEMFC) using plasma surface diffusion alloying. The electrochemical behaviour of the niobium carbide diffusion-modified 304 SS (Nb-C 304 SS) is investigated in simulated PEMFC environments (0.5 M H2SO4 and 2 ppm HF solution at 80 °C). Potentiodynamic, potentiostatic polarisation and electrochemical impedance spectroscopy measurements reveal that the niobium carbide diffusion layer considerably improves the corrosion resistance of 304 SS compared with untreated samples. The corrosion current density of Nb-C 304 SS is maintained at 0.058 μA cm-2 and 0.051 μA cm-2 under simulated anodic and cathodic conditions, respectively. The interfacial contact resistance of Nb-C 304 SS is 8.47 mΩ cm2 at a compaction force of 140 N cm-2, which is significantly lower than that of the untreated sample (100.98 mΩ cm2). Moreover, only a minor increase in the ICR of Nb-C 304 SS occurs after 10 h potentiostatic tests in both cathodic and anodic environments.

  15. Corrosion behaviours of the dental magnetic keeper complexes made by different alloys and methods

    Science.gov (United States)

    Wu, Min-Ke; Song, Ning; Liu, Fei; Kou, Liang; Lu, Xiao-Wen; Wang, Min; Wang, Hang; Shen, Jie-Fei

    2016-01-01

    The keeper and cast dowel–coping, as a primary component for a magnetic attachment, is easily subjected to corrosion in a wet environment, such as the oral cavity, which contains electrolyte-rich saliva, complex microflora and chewing behaviour and so on. The objective of this in vitro study was to examine the corrosion resistance of a dowel and coping-keeper complex fabricated by finish keeper and three alloys (cobalt–chromium, CoCr; silver–palladium–gold, PdAu; gold–platinum, AuPt) using a laser-welding process and a casting technique. The surface morphology characteristics and microstructures of the samples were examined by means of metallographic microscope and scanning electron microscope (SEM). Energy-dispersive spectroscopy (EDS) with SEM provided elements analysis information for the test samples after 10% oxalic acid solution etching test. Tafel polarization curve recordings demonstrated parameter values indicating corrosion of the samples when subjected to electrochemical testing. This study has suggested that massive oxides are attached to the surface of the CoCr–keeper complex but not to the AuPt–keeper complex. Only the keeper area of cast CoCr–keeper complex displayed obvious intergranular corrosion and changes in the Fe and Co elements. Both cast and laser-welded AuPt–keeper complexes had the highest free corrosion potential, followed by the PdAu–keeper complex. We concluded that although the corrosion resistance of the CoCr–keeper complex was worst, the keeper surface passive film was actually preserved to its maximum extent. The laser-welded CoCr– and PdAu–keeper complexes possessed superior corrosion resistance as compared with their cast specimens, but no significant difference was found between the cast and laser-welded AuPt–keeper complexes. The Fe-poor and Cr-rich band, appearing on the edge of the keeper when casting, has been proven to be a corrosion-prone area. PMID:27388806

  16. Application of electrochemical frequency modulation for monitoring corrosion and corrosion inhibition of iron by some indole derivatives in molar hydrochloric acid

    International Nuclear Information System (INIS)

    Khaled, K.F.

    2008-01-01

    The corrosion inhibition effect of four indole derivatives, namely indole (IND), benzotriazole (BTA), benzothiazole (BSA) and benzoimidazole (BIA), have been used as possible corrosion inhibitors for pure iron in 1 M HCl. In this study, electrochemical frequency modulation, EFM was used as an effective method for corrosion rate determination in corrosion inhibition studies. By using EFM measurements, corrosion current density was determined without prior knowledge of Tafel slopes. Corrosion rates obtained using EFM, were compared to that obtained from other chemical and electrochemical techniques. The results obtained from EFM, EIS, Tafel and weight loss measurements were in good agreement. Tafel polarization measurements show that indole derivatives are cathodic-type inhibitors. Molecular simulation studies were applied to optimize the adsorption structures of indole derivatives. The inhibitor/iron/solvent interfaces were simulated and the adsorption energies of these inhibitors were calculated. Quantum chemical calculations have been performed and several quantum chemical indices were calculated and correlated with the corresponding inhibition efficiencies

  17. Development of new corrosion inhibitor tested on mild steel supported by electrochemical study

    Science.gov (United States)

    Habeeb, Hussein Jwad; Luaibi, Hasan Mohammed; Dakhil, Rifaat Mohammed; Kadhum, Abdul Amir H.; Al-Amiery, Ahmed A.; Gaaz, Tayser Sumer

    2018-03-01

    Mild steel is a metal which is commonly used in industrials and manufacturing of equipment for most industries round the world. It is cheaper cost compared with the other metals and its durable, hard and easy-to-wear physical properties make it a major choice in the manufacture of equipment parts. The main problem through the uses of mild steel in industry is its resistance against corrosion, especially in acidic solutions. This case led to raise the cost of maintenance of equipment that used mild steel and as a result increased costs for the company. Organic corrosive inhibitors that also act as green chemicals, 4-hydroxybenzylideneaminomethyl-5-ethyl-1,3,4-thiadiazol have been synthesized. This inhibitor is tested as corrosion inhibitor on a mild steel sample MS in 1 M hydrochloric acid solution (HCl) using electrochemical measurements test includes PD (Potentiodynamic), EIS (Electrochemical impedance spectroscopy), OCP (Open circuit potential) and EFM (electrochemical frequency modulation). The obtained results indicate that 4-hydroxybenzylideneaminomethyl-5-ethyl-1,3,4-thiadiazol acts as a good corrosion inhibitor for mild steel sample in HCl solution with efficiency above 90%. Changes in the impedance parameters postulated adsorption on the mild steel specimens' surfaces of, which it going to the formation of protective coating layer. It also shows that 4-hydroxybenzylideneaminomethyl-5-ethyl-1,3,4-thiadiazol corrosion inhibitors are effective in helping to reduce and slow down the corrosion process that occurs on mild steel surface in hydrochloric acid solution. Increase of corrosion inhibitor concentration provides a protective layer of mild steel. However, this protective layer becomes weak when the temperature of the solution increases.

  18. ELECTROCHEMICAL CORROSION STUDY VIA LINEAR POLARIZATION IN PEAS CAN

    Directory of Open Access Journals (Sweden)

    I. M. Costa

    2016-09-01

    Full Text Available The aim of this work is to study the corrosion of tinplate can for peas. Firstly, the characterization of canning solution was made. The values of pH, conductivity, Brix, viscosity, density and content of Fe were, respectively, 5.88; 32.6 mS/cm; 6.6%; 3,42cP; 1.026 g/ml; 12.05 mg/kg. The corrosion rate in the cans was determined by linear polarization technique. The electrodes with and without varnish were analyzed in the first and fifth day of the experiment for the 3 parts of the can. The corrosion rate increased significantly when the coating was removed and the body showed a higher corrosion rate, reaching 1.7 mm/year in the absence of varnish. The microstructure of the samples was evaluated by scanning electron microscopy (SEM coupled with energy dispersive spectroscopy (EDS. The increase of iron on the surface, evidenced by energy dispersive spectroscopy (EDS may have contributed to the corrosion in the samples without varnish.

  19. Influence of the degree of polishing of alloy AA 5083 on its behaviour against localised alkaline corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Aballe, A.; Bethencourt, M.; Botana, F.J.; Marcos, M.; Sanchez-Amaya, J.M

    2004-08-01

    A study has been conducted of the influence of the surface finish on the behaviour against the corrosion of samples of alloy AA 5083 immersed in aerated solutions of NaCl at 3.5%. Samples polished from 80 to 1200 grit have been tested, utilising as experimental techniques, measurements of weight loss, optical and scanning electron microscopy, linear polarisations and electrochemical noise measurement (ENM). In the conditions studied, the principal corrosion process that takes place is localised alkaline corrosion (LAC). This type of corrosion occurs as a consequence of the alkalinisation of the area surrounding the Al(Mn,Fe,Cr) cathodic precipitates that exist in the alloy. The results obtained indicate that the samples polished to 1200 grit present a greater susceptibility to processes of localised alkaline corrosion than the samples polished to 80 grit. It has been found that the degree of polishing conditions the number of intermetallic particles exposed. Hence the differences of behaviour observed between the sets of results obtained have been interpreted as an effect function of the density of cathodic intermetallic particles exposed on the surface.

  20. Application of Corrosion Test for Austenitic SS 304 in PWR with Electrochemical Quartz Crystal Microbalance (EQCM)

    International Nuclear Information System (INIS)

    Park, Jeong Seok; Shin, Sang Hun; Kim, Jong Jin; Kim, Ji Hyun

    2011-01-01

    and coolant water. Electrochemical Quartz Crystal Microbalance is a new electrochemical technique developed in recent years able to be applied to study the filming kinetics of corrosion phenomena using piezoelectric effect. The high sensitivity of EQCM is the basis for its applications in thin film studies. In addition, interfacial process can be measured with the exact time scale depending on the frequency counter used. The purpose of this study is to understand the corrosion inhibition mechanisms of pitting corrosion for stainless steel 304 using inhibitor based on phosphoric acid and to contribute the application of corrosion test by EQCM techniques for corrosion research of steam condenser tube exposed of seawater coolant in the secondary system of NPP

  1. Electrochemical corrosion characteristics and biocompatibility of nanostructured titanium for implants

    Science.gov (United States)

    Lu, Jinwen; Zhang, Yong; Huo, Wangtu; Zhang, Wei; Zhao, Yongqing; Zhang, Yusheng

    2018-03-01

    In the present study, a nano-grained (NG) surface layer on a commercial pure (Grade-2) titanium sheet was achieved by means of sliding friction treatment. The surface characteristics, in vitro corrosion behavior and biocompatibility of NG Ti were investigated, compared with those of the conventional coarse-grained (CG) substrate. The protective passive film on NG Ti surface is thicker than that on CG Ti, leading to its enhanced biological corrosion resistance in simulated body fluid (SBF) solution. In addition, NG Ti shows a much higher hydrophilicity and nano-roughness, which is related to its significantly improved cell attachment, spreading, proliferation and maturation relative to CG Ti. The enhanced biological anti-corrosion properties and biocompatibility render NG Ti a promising biomaterial for implants.

  2. Effect of red mud addition on the corrosion parameters of reinforced concrete evaluated by electrochemical methods

    Directory of Open Access Journals (Sweden)

    D.V. Ribeiro

    Full Text Available Red mud, the main waste generated in aluminum and alumina production from bauxite ore by the Bayer process, is considered "hazardous" due to its high pH. The high pH also provides greater protection of rebars, which is reflected in the low corrosion potential and high electrical resistivity (filler effect of concrete. The corrosion potential was monitored by electrochemical measurements and the electrical resistivity was evaluated using sensors embedded in concrete test specimens. The results showed that the addition of red mud is beneficial to concrete, reducing its corrosion potential and increasing its electrical resistivity. Red mud proved to be a promising additive for concrete to inhibit the corrosion process.

  3. Corrosion behaviour of low alloy steels: from ancient past to far future

    International Nuclear Information System (INIS)

    Santarini, G.

    2004-01-01

    With the envisaged concepts of long term storage and underground disposal of high level radioactive waste, corrosion science has to face a new challenge: to obtain reliable behaviour predictions over very long periods of time, up to thousands of years. For such durations, the development of mechanistically based models becomes an absolute necessity. In France, the first candidate materials considered for the containers of high level waste are low alloy steels because of their relatively low sensitivity to localized corrosion, when compared, for example, to passive materials: this characteristics makes their corrosion behaviour less difficult to predict. In this mechanistic modelling, numerous physicochemical steps have to be taken into consideration, such as chemical and/or electrochemical reactions, solid state diffusion of point defects, liquid state diffusion of chemical species in oxide pores, etc. However, since the complex links between all these steps highly depend on the nature and on the characteristics (porosity, conductivity, protectiveness, etc.) of the corrosion products, the first stage before the model construction is to obtain experimental data on this phenomenology in the very near environment of the metal. At the opposite, once a model constructed, it is necessary to compare its predictions to field experience, and to verify that the mechanisms and phenomenology retained in the model remain unchanged over very long periods of time. In the various stages of a progressive iterative model improvement, the examination of archaeological objects is liable to provide useful information. The considerable interest of such objects, in this context, comes from the long duration of the contact with a natural environment, a duration of the same order of magnitude as the one considered for high level waste storage. However, the differences between the ancient materials and the modern ones and also the poor knowledge about the initial conditions and about the

  4. The electrochemical impedance spectroscopy of silver doped hydroxyapatite coating in simulated body fluid used as corrosive agent

    Directory of Open Access Journals (Sweden)

    Mišković-Stanković Vesna

    2012-01-01

    Full Text Available Titanium is a key biomedical material due its good biocompatibility, mechanical properties and corrosion stability, but infections of the implantation site still pose serious threat. One approach to prevent infection is to improve antimicrobial ability of the coating material. Silver doped hydroxyapatite (Ag/HAP nanoparticles were synthesized by new modified precipitation method. The synthesized powder was used for preparation of Ag/HAP coating on titanium by electrophoretic deposition. The coating was characterized in terms of phase composition and structure by Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR and X-ray diffraction (XRD; surface morphology and chemical composition was assessed using scanning electron microscopy (SEM and energy dispersive spectroscopy (EDS. Research focused on evaluation of the corrosion behaviour of Ag/HAP coating in simulated body fluid (SBF at 37 ºC during prolonged immersion time by electrochemical impedance spectroscopy (EIS. Silver doped HAP coating provided good corrosion protection in SBF solution. [Acknowledgements. This research was financed by the Ministry of Education, Science and Technological Development of the Republic of Serbia, contracts No. III 45019 and by National Sciences and Engineering Research Council of Canada (NSERC. Dr Ana Jankovic was financed by the FP7 Nanotech FTM Grant Agreement 245916

  5. [Corrosion of Ag-Pd-Cu alloys in saline solution. Amount of released elements and electrochemical corrosion].

    Science.gov (United States)

    Kitaoka, M

    1989-03-01

    The effect of the Pd content on corrosion and tarnish resistance in twelve experimental alloys was investigated. The alloys were prepared with a composition of Pd content from 20.1 to 30.1 at %. The composition of the alloys Ag-20% Pd, Ag-25% Pd and Ag-30% Pd was varied by adding Cu 5 wt%, 10 wt% and 15 wt% to each of them. The corrosion resistance was estimated by the amount of the released Ag, Cu and by electrochemical corrosion behavior in 0.86% NaCl solution at 37 degrees C. The tarnish resistance was assessed using a spectrophotometer. The test solutions included 0.86% NaCl solution, 0.1% Na2S solution and a mixture of 1.0% lactic acid and 0.1% Na2S, all at 37 degrees C, in sealed containers. The results are summarized as follows. The larger the amount of Pd in Ag-Pd binary alloys and Ag-Pd-Cu ternary alloys, the more stable was the release and the release rate of Ag, Cu and corrosion resistance increased in 0.86% NaCl solution. The addition of Cu to Ag-Pd binary alloys increased the release and release rate of Ag, but there was a shift of the rest potential in the noble direction. A relationship was found between the amount of Ag and Cu released from Ag-Pd-Cu ternary alloys. In this study, an increase in corrosion resistance was observed when the content of Pd in Ag-Pd binary alloys was 25 wt%. Furthermore, it was also observed that Ag-Pd-Cu ternary alloys need an additional 30 wt% Pd for corrosion resistance. Moreover, the addition of Cu must be kept lower than 10 wt%. The tarnish resistance of the twelve experimental alloys was good in 0.86% NaCl solution but was barely improved with increased in the Pd content in sulfide solution. The correlation between electrochemical corrosion behavior and tarnish resistance was not significant, but the correlation between the amount of Ag, Cu release from Ag-Pd-Cu ternary alloys and tarnish resistance was remarkable.

  6. Electrochemical anodizing treatment to enhance localized corrosion resistance of pure titanium.

    Science.gov (United States)

    Prando, Davide; Brenna, Andrea; Bolzoni, Fabio M; Diamanti, Maria V; Pedeferri, Mariapia; Ormellese, Marco

    2017-01-26

    Titanium has outstanding corrosion resistance due to the thin protective oxide layer that is formed on its surface. Nevertheless, in harsh and severe environments, pure titanium may suffer localized corrosion. In those conditions, costly titanium alloys containing palladium, nickel and molybdenum are used. This purpose investigated how it is possible to control corrosion, at lower cost, by electrochemical surface treatment on pure titanium, increasing the thickness of the natural oxide layer. Anodic oxidation was performed on titanium by immersion in H2SO4 solution and applying voltages ranging from 10 to 80 V. Different anodic current densities were considered. Potentiodynamic tests in chloride- and fluoride-containing solutions were carried out on anodized titanium to determine the pitting potential. All tested anodizing treatments increased corrosion resistance of pure titanium, but never reached the performance of titanium alloys. The best corrosion behavior was obtained on titanium anodized at voltages lower than 40 V at 20 mA/cm2. Titanium samples anodized at low cell voltage were seen to give high corrosion resistance in chloride- and fluoride-containing solutions. Electrolyte bath and anodic current density have little effect on the corrosion behavior.

  7. Study crevice corrosion alloys C-22 and 625 by electrochemical noise

    International Nuclear Information System (INIS)

    Ungaro, María L.; Carranza, Ricardo M.; Rodríguez, Martín A.

    2013-01-01

    C-22 and 625 alloys are two of the Ni –Cr-Mo alloys considered as candidate materials to form the corrosion resistance engineered barriers for nuclear waste repositories. The corrosion resistance of these alloys is remarkable in a wide variety of environments. Despite of their resistance these alloys are susceptible to crevice corrosion in a certain aggressive environments. This work presents the use of electrochemical noise technique to study crevice corrosion susceptibility of alloys C-22 and 625 in 1M NaCl acidic solutions at 60ºC and 90ºC. Asymmetrical electrodes and a complementary platinum electrode were used to assess the influence of cathodic reaction in crevice process. The obtained records were analyzed directly and through statistical parameters. The potential drop and the simultaneous increment of the current records indicated the occurrence of crevice corrosion. The alternative use of a platinum electrode resulted in higher currents and higher potentials and reduced the induction time to crevice formation. The reason for this behavior is that platinum surface allows faster cathodic reactions than C-22 and 625 alloys. The standard deviation of the current records was responsive to the crevice corrosion intensity. C-22 alloy had better crevice corrosion performance than 625 alloy. (author)

  8. Electrochemical Sensors for Monitoring the Corrosion Conditions of Reinforced Concrete Structures: A Review

    Directory of Open Access Journals (Sweden)

    Rita B. Figueira

    2017-11-01

    Full Text Available Several methods for corrosion monitoring of reinforced concrete structures (RCS have been proposed in the last few decades. These systems may be used either in new, existing or repaired structures. The corrosion monitoring can be performed by different methodologies. These may or may not be destructive, use different degrees of complexity and cost, and provide information on the progression and kinetics of the corrosion phenomena. The destructive methods are limited to sampling. Therefore, these may not be representative of the whole structure, which is extremely important in RCS with large heterogeneities both in terms of materials used and in terms of the exposure environment. Within this context, non-destructive methods have been widely developed, which are intended to provide quick information about the entire structure. Ideally, these systems should be able to detect the corrosion state of the steel inside the concrete, the main causes of corrosion and the evolution of corrosion phenomena over time. This manuscript reviews and summarizes the actual state of the art and the main achievements in the field of electrochemical sensors based on non-destructive methods for corrosion monitoring of RCS in the last few years. The challenges and perspectives in this field will also be discussed.

  9. Effects of chitosan inhibitor on the electrochemical corrosion behavior of 2205 duplex stainless steel

    Science.gov (United States)

    Yang, Se-fei; Wen, Ying; Yi, Pan; Xiao, Kui; Dong, Chao-fang

    2017-11-01

    The effects of chitosan inhibitor on the corrosion behavior of 2205 duplex stainless steel were studied by electrochemical measurements, immersion tests, and stereology microscopy. The influences of immersion time, temperature, and chitosan concentration on the corrosion inhibition performance of chitosan were investigated. The optimum parameters of water-soluble chitosan on the corrosion inhibition performance of 2205 duplex stainless steel were also determined. The water-soluble chitosan showed excellent corrosion inhibition performance on the 2205 duplex stainless steel. Polarization curves demonstrated that chitosan acted as a mixed-type inhibitor. When the stainless steel specimen was immersed in the 0.2 g/L chitosan solution for 4 h, a dense and uniform adsorption film covered the sample surface and the inhibition efficiency (IE) reached its maximum value. Moreover, temperature was found to strongly influence the corrosion inhibition of chitosan; the inhibition efficiency gradually decreased with increasing temperature. The 2205 duplex stainless steel specimen immersed in 0.4 g/L water-soluble chitosan at 30°C displayed the best corrosion inhibition among the investigated specimens. Moreover, chitosan decreased the corrosion rate of the 2205 duplex stainless steel in an FeCl3 solution.

  10. Corrosion detection of carbon steel in water/oil two phases environment by electrochemical noise analysis

    International Nuclear Information System (INIS)

    Gusmano, G.; Montesperelli, G.; De Grandis, A.

    1998-01-01

    The aim of this paper is to demonstrate the effectiveness of the electrochemical noise analysis to detect the onset of corrosion phenomena in a very high resistivity medium. Tests were carried out on carbon steel electrodes immersed in a water/mineral oil two phases environment with high concentration of CO 2 , different aqueous/organic phase ratio, sulphide content between 0 and 0.5 g/l and pH between 1 and 5. The evolution of corrosion phenomena were followed by collecting current and potential noise between three nominally identical electrodes. The noise data were analysed in the time and in the frequency domain. In spite of a great loss of sensitivity of the method with respect to tests performed in aqueous solution, the data indicate a good agreement between the standard deviations and the power level of power spectra density (PSD) of current and potential noise signals and corrosion rates by means of weight loss. The values of the PSD slope, indicate the form of corrosion. The effect of water/oil ratio, sulphide concentration and pH on the corrosion rate was determined. Finally two methods to increase the sensitivity of the electrochemical noise are proposed. (orig.)

  11. Electrochemical corrosion behavior of AZ91D alloy in ethylene glycol

    Energy Technology Data Exchange (ETDEWEB)

    Fekry, A.M. [Chemistry Department, Faculty of Science, Cairo University, Giza 12613 (Egypt)], E-mail: hham4@hotmail.com; Fatayerji, M.Z. [Chemistry Department, Faculty of Science, Cairo University, Giza 12613 (Egypt)

    2009-11-01

    The effect of concentration on the corrosion behavior of Mg-based alloy AZ91D was investigated in ethylene glycol-water solutions using electrochemical techniques i.e. potentiodynamic polarization, electrochemical impedance measurements (EIS) and surface examination via scanning electron microscope (SEM) technique. This can provide a basis for developing new coolants for magnesium alloy engine blocks. Corrosion behavior of AZ91D alloy by coolant is important in the automotive industry. It was found that the corrosion rate of AZ91D alloy decreased with increasing concentration of ethylene glycol. For AZ91D alloy in chloride >0.05 M or fluoride <0.05 M containing 30% ethylene glycol solution, they are more corrosive than the blank (30% ethylene glycol-70% water). However, at concentrations <0.05 for chloride or >0.05 M for fluoride containing ethylene glycol solution, some inhibition effect has been observed. The corrosion of AZ91D alloy in the blank can be effectively inhibited by addition of 0.05 mM paracetamol that reacts with AZ91D alloy and forms a protective film on the surface at this concentration as confirmed by surface examination.

  12. The influence of current collector corrosion on the performance of electrochemical capacitors

    Science.gov (United States)

    Wojciechowski, Jarosław; Kolanowski, Łukasz; Bund, Andreas; Lota, Grzegorz

    2017-11-01

    This paper discusses the effect of current collector (stainless steel 316L) corrosion on the performance of electrochemical capacitors operated in aqueous electrolytes. This topic seems to be often neglected in scientific research. The studied electrolytes were 1 M H2SO4, 1 M KI, 1 M Na2SO4, 1 M KOH and 6 M KOH. The corrosion process was investigated by means of selected direct and alternating current techniques. The surface of the current collectors as well as the corrosion products were characterised using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy and atomic force microscopy. Stainless steel 316L in alkaline solutions is characterised by the lowest values of corrosion potentials whereas the potentials in acidic media become the most noble. Our studies show that corrosion potentials increase with decreasing pH value. This phenomenon can be explained with the formation of passive oxide films on the stainless steel current collectors. The passive oxide films are usually thicker and more porous in alkaline solutions than that in the other electrolytes. The processes occurring at the electrode/electrolyte interfaces strongly influence the working parameters of electrochemical capacitors such as voltage, working potentials of single electrodes, self-discharge as well as the internal resistance and cycling stability.

  13. Electrochemical behavior and corrosion resistance of Ti-15Mo alloy in naturally-aerated solutions, containing chloride and fluoride ions.

    Science.gov (United States)

    Rodrigues, A V; Oliveira, N T C; dos Santos, M L; Guastaldi, A C

    2015-01-01

    The electrochemical behavior and corrosion resistance of Ti-15Mo alloy to applications as biomaterials in solutions 0.15 mol L(-1) Ringer, 0.15 mol L(-1) Ringer plus 0.036 mol L(-1) NaF and 0.036 mol L(-1) NaF (containing 1,500 ppm of fluoride ions, F(-)) were investigated using open-circuit potential, cyclic voltammetry, and electrochemical impedance spectroscopy techniques, X-ray photoelectron spectroscopy and scanning electron microscope. Corrosion resistance and electrochemical stability of the Ti-15Mo alloy decreased in solutions containing F(-) ions. In all cases, there were formation and growth of TiO2 and MoO3 (a protector film), not being observed pitting corrosion, which might enable Ti-15Mo alloys to be used as biomedical implant, at least in the studied conditions, since the electrochemical stability and corrosion resistance of the passive films formed are necessary conditions for osseointegration.

  14. A Plan to Develop and Demonstrate Electrochemical Noise Based Corrosion Monitoring Systems in Hanford Site Waste Tanks

    International Nuclear Information System (INIS)

    NORMAN, E.C.

    2000-01-01

    This document describes changes that need to be made to the site's authorization basis and technical concerns that need to be resolved before proceduralized use of Electrochemical Noise based corrosion monitoring systems is fully possible at the Hanford Site

  15. Corrosion behaviour of a sintered 316L with different porosity grades

    International Nuclear Information System (INIS)

    Soria, L.; Gomez, F.; Gallardo, J.M.; Herrera, E.J.

    1998-01-01

    AISI 316L sintered samples, with porosities ranging from 9 to 40%, and without alloying losses at the surface, have been prepared. Those samples, along with conventional (rolled) steel samples, have been subjected to electrochemical and immersion corrosion tests. According to porosity size quantitative measurements, before and after corrosion tests, two corrosion mechanisms, general and pitting, are proposed depending on the initial porosity. (Author) 17 refs

  16. Electrochemical Techniques Applied to Studies of Microbiologically Influenced Corrosion (MIC)

    Science.gov (United States)

    1992-01-01

    corrosion (MIC). Applications Include evaluation of MIC of metals exposed 7, to seawater, fresh water, demineralized water, process chemicals, food stuffs...water, process chemicals, food stuffs, soils, aircraft important to focus elecatrochemical investigations notfuels, human plasma, and sewage. In this...negative than (CONICET-NSF). LaPlata, Argentina, Aquatec, E,., Progress can only be made if surface analytical Quimica , pp. 119-133 techniques are

  17. Correlation of Process Data and Electrochemical Noise to Assess Kraft Digester Corrosion: Kamloops Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, SJ

    2002-05-09

    Electrochemical noise (ECN) probes were deployed in a carbon steel continuous kraft digester at five locations roughly equi-spaced from top to bottom of the vessel. Current and potential noise, the temperature at each probe location, and the value of about 60 process parameters (flow rates, liquor chemistry, etc.) were monitored continuously for a period of one year. Historical vessel inspection data, including inspections accomplished immediately prior to and immediately following probe deployment, and post-test evaluation of the probe components were used to assess/compare corrosion indications from the probes with physical changes in wall thickness and corrosion patterns on the digester shell. The results indicate that furnish composition is a significant variable influencing digester corrosion, with increasing amounts of Douglas fir in the nominal furnish correlating directly with increased corrosion activity on the ECN probes. All five probes detected changes in furnish composition approximately simultaneously, indicating rapid chemical communication through the liquor, but the effect was strongest and persisted longest relatively high in the digester. The ECN probes also indicate significant corrosion activity occurred at each probe position during shutdown/restart transients. Little or no correlation between ECN probe corrosion activity and other operational variables was observed. Post-test evaluation of the probes confirmed general corrosion of a magnitude that closely agreed with corrosion current sums calculated for each probe over the exposure period and with historical average corrosion rates for the respective locations. Further, no pitting was observed on any of the electrodes, which is consistent with the ECN data, relevant polarization curves developed for steel in liquor removed from the digester, and the post-test inspection of the digester.

  18. The corrosion behaviour of nanograined metals and alloys

    Directory of Open Access Journals (Sweden)

    Herrasti, P.

    2012-10-01

    Full Text Available There has been considerable interest in the properties of nanocrystalline materials over the last decade. Such materials include metals and alloys with a crystal size within the order of 1 to 100 nm. The interest arises due to the substantial differences in electrical, optical and magnetic properties and also due to their high adsorption capability and chemical reactivity compared to their larger grained counterparts. In this paper, the corrosion of nanocrystalline metals and alloys is investigated and compared to the corrosion of microcrystalline materials having a similar composition. The focus is on the corrosion of nickel, copper, cobalt and iron alloys. Key aspects of different corrosion behaviour such grain boundaries and size are identified.

    En la última década ha habido un gran interes en las propiedades de materiales nanocristalinos. Estos materiales incluyen metales y aleaciones con un tamaño de cristal del orden de 1 a 100 nm. El interes por estos materiales es debido a las grandes diferencias en cuanto a sus propiedades electricas, opticas y magneticas, asi como a su alta capacidad de adsorción y reactividad química en relación a los mismos materiales con tamaños de grano mayores. En este trabajo se ha investigado y comparado la corrosión de materiales nano y microcristalinos de similar composición química. Principalmente se ha centrado en la corrosión de metales tales como niquel, cobre, cobalto y aleaciones de hierro. Se ha comprobado que los diferentes comportamientos frente al proceso de corrosión están intimamente ligados con los bordes de grano y el tamaño de dichos granos.

  19. Application of a passive electrochemical noise technique to localized corrosion of candidate radioactive waste container materials

    International Nuclear Information System (INIS)

    Korzan, M.A.

    1994-05-01

    One of the key engineered barriers in the design of the proposed Yucca Mountain repository is the waste canister that encapsulates the spent fuel elements. Current candidate metals for the canisters to be emplaced at Yucca Mountain include cast iron, carbon steel, Incoloy 825 and titanium code-12. This project was designed to evaluate passive electrochemical noise techniques for measuring pitting and corrosion characteristics of candidate materials under prototypical repository conditions. Experimental techniques were also developed and optimized for measurements in a radiation environment. These techniques provide a new method for understanding material response to environmental effects (i.e., gamma radiation, temperature, solution chemistry) through the measurement of electrochemical noise generated during the corrosion of the metal surface. In addition, because of the passive nature of the measurement the technique could offer a means of in-situ monitoring of barrier performance

  20. Electrochemical assessing corrosion inhibiting effects of zinc aluminum polyphosphate (ZAPP) as a modified zinc phosphate pigment

    International Nuclear Information System (INIS)

    Naderi, R.; Attar, M.M.

    2008-01-01

    Undesirable anti-corrosion performance of zinc phosphate pigment, the classical chromate replacement, has led researchers to take modification into account. Polyphosphate-based anti-corrosion pigments as a result of modification of zinc orthophosphate have been found to function much more efficiently. This study aimed to evaluate performance of steel samples immersed in 3.5% NaCl aqueous solution-containing zinc aluminum polyphosphate (ZAPP) pigment extract compared to those involving conventional zinc phosphate (ZP) pigment extract and also no pigment (blank) using electrochemical tests such as electrochemical impedance spectroscopy (EIS) and linear polarization (LP) as well as surface analysis. Impedance spectra and polarization curves revealed two different trends, showing the superiority of ZAPP pigment. Based on the results of scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), presence of a precipitated layer on the surface was confirmed when steel sample was immersed into the solution-containing ZAPP

  1. Investigations on Microstructure and Corrosion behavior of Superalloy 686 weldments by Electrochemical Corrosion Technique

    Science.gov (United States)

    Arulmurugan, B.; Manikandan, M.

    2018-02-01

    In the present study, microstructure and the corrosion behavior of Nickel based superalloy 686 and its weld joints has been investigated by synthetic sea water environment. The weldments were fabricated by Gas Tungsten Arc Welding (GTAW) and Pulsed Current Gas Tungsten Arc Welding (PCGTAW) techniques with autogenous mode and three different filler wires (ERNiCrMo-4, ERNiCrMo-10 and ERNiCrMo-14). Microstructure and Scanning electron microscope examination was carried out to evaluate the structural changes in the fusion zones of different weldments. Energy Dispersive X-ray Spectroscopy (EDS) analysis was carried out to evaluate the microsegregation of alloying elements in the different weld joints. Potentiodynamic polarization study was experimented on the base metal and weld joints in the synthetic sea water environment to evaluate the corrosion rate. Tafel’s interpolation technique was used to obtain the corrosion rate. The microstructure examination revealed that the fine equiaxed dendrites were observed in the pulsed current mode. EDS analysis shows the absence of microsegregation in the current pulsing technique. The corrosion rates of weldments are compared with the base metal. The results show that the fine microstructure with the absence of microsegregation in the PCGTA weldments shows improved corrosion resistance compared to the GTAW. Autogenous PCGTAW shows higher corrosion resistance irrespective of all weldments employed in the present study.

  2. Effect of hydrogen uptake on the electrochemical corrosion of N18 zircaloy under gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Z.Y. [Lab of Advanced Materials, School of Materials Sciences and Engineering, Tsinghua University, Beijing 100084 (China); Ling, Y.H., E-mail: yhling@mail.tsinghua.edu.cn [Lab of Advanced Materials, School of Materials Sciences and Engineering, Tsinghua University, Beijing 100084 (China); Bai, Y.K.; Zeng, C.; Wang, S. [Lab of Advanced Materials, School of Materials Sciences and Engineering, Tsinghua University, Beijing 100084 (China); Clara, J.C. [Department of Chemistry, University of Western Ontario, London N6A 5B7, Ontario (Canada)

    2016-12-01

    Highlights: • Hydrogen permeation can promote the corrosion rate of N18 zircaloy. • Gamma irradiation can further accelerate the corrosion process. • A novel mechanism based on point defects was proposed to explain the relevant phenomena. - Abstract: It has been well recognized that dramatic hydrogen uptake occurred in zircaloy after kinetic transition and porous structure was observed subsequently due to phase transformation of tetragonal to monoclinic zirconia. Therefore, how hydrogen solute and gamma-induced capillary-embedded hydrolysis influence the corrosion of zircaloy is an intriguing issue. In this work, the effect of hydrogen uptake and gamma irradiation on corrosion of N18 zircaloy was studied. Raman spectra and atomic force microscopy (AFM) were employed to analyse phase structure and surface morphology. Potentiodynamic polarization and electrochemical impedance spectroscopy were utilized to qualitatively evaluate the electron transfer properties of the oxide film formed on the zircaloy surface after corrosion. The depth profile and surface chemical states of involving elements were analysed by auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), respectively. It was found that hydrogen permeation can decline the integrity and impedance semicircle of the oxide films, the more the hydrogen uptake is; the smaller magnitude of impedance will be. In view of the gamma irradiation, it is demonstrated that it promotes the corrosion rate slightly. Based on the irradiation theory and existing phenomena, the underlying mechanism is proposed.

  3. The Electrochemical Investigation of the Corrosion Rates of Welded Pipe ASTM A106 Grade B

    Directory of Open Access Journals (Sweden)

    Trinet Yingsamphancharoen

    2016-08-01

    Full Text Available The aim of this work was to investigate the corrosion rate of welded carbon steel pipe (ASTM (American Society for Testing and Materials A106 Grade B by GTAW under the currents of 60, 70, and 80 A. All welded pipes satisfied weld procedure specifications and were verified by a procedure qualification record. The property of used materials was in agreement with the ASME standard: section IX. The welded pipe was used for schematic model corrosion measurements applied in 3.5 wt % NaCl at various flow rates and analyzed by using the electrochemical technique with Tafel’s equation. The results showed the correlation between the flow rate and the corrosion rate of the pipe; the greater the flow rate, the higher corrosion rate. Moreover, the welded pipe from the welding current of 70 A exhibited higher tensile strength and corrosion resistance than those from currents of 60 and 80 A. It indicated that the welding current of 70 A produced optimum heat for the welding of A106 pipe grade B. In addition, the microstructure of the welded pipe was observed by SEM. The phase transformation and crystallite size were analyzed by XRD and Sherrer’s equation. The results suggested that the welding current could change the microstructure and phase of the welded pipe causing change in the corrosion rate.

  4. Electrochemical impedance pattern recognition for detection of hidden chemical corrosion on aircraft components, phase 1

    Science.gov (United States)

    Sammells, A. F.; Bowers, J. S.

    1995-02-01

    This investigation addressed the need for diagnostic instrumentation compatible with performing the Nondestructive Evaluation (NDE) of hidden chemical corrosion with a high degree of accuracy, sensitivity and versatility on both titanium and aluminum alloys currently used in Air Force and commercial aircraft. The overall approach was directed towards development of pattern recognition schemes based upon the on-line data acquisition of Fast Fourier Transform Electrochemical Impedance Spectroscopy (FFTEIS) instrumentation from the suspect hidden chemical corrosion site. Resulting impedance patterns were then analyzed by application of a Neural Network pattern recognition scheme. The Neural Network Analysis (NNA) was then trained to both detect and grade the severity of hidden corrosion present on the aircraft metal substrate interface of interest. Nueral Net Analysis of FFTEIS data was verified as a powerful diagnostic strategy for in situ hidden corrosion process identification, quantitative analysis and severity grading. Correlations between impedance measurements and corrosion depth were verified by subsequent SEM and EDX examination of the metal interfacial regions. The approach will also be powerful for gaining fundamental information into the nature of corrosion processes and conditions leading to their inception at hidden sites.

  5. Corrosion Behaviour of Mg Alloys in Various Basic Media: Application of Waste Encapsulation of Fuel Decanning from UNGG Nuclear Reactor

    Science.gov (United States)

    Lambertin, David; Frizon, Fabien; Blachere, Adrien; Bart, Florence

    The dismantling of UNGG nuclear reactor generates a large volume of fuel decanning. These materials are based on Mg-Zr alloy. The dismantling strategy could be to encapsulate these wastes into an ordinary Portland cement (OPC) or geopolymer (aluminosilicate material) in a form suitable for storage. Studies have been performed on Mg or Mg-Al alloy in basic media but no data are available on Mg-Zr behaviour. The influence of representative pore solution of both OPC and geopolymer with Mg-Zr alloy has been studied on corrosion behaviour. Electrochemical methods have been used to determine the corrosion densities at room temperature. Results show that the corrosion densities of Mg-Zr alloy in OPC solution is one order of magnitude more important than in a geopolymer solution environment and the effect of an inhibiting agent has been undertaken with Mg-Zr alloy. Evaluation of corrosion hydrogen production during the encapsulation of Mg-Zr alloy in both OPC and geopolymer has also been done.

  6. Electrodeposition, characterization and corrosion behaviour of tin-20 wt.% zinc coatings electroplated from a non-cyanide alkaline bath

    International Nuclear Information System (INIS)

    Dubent, S.; Mertens, M.L.A.D.; Saurat, M.

    2010-01-01

    Tin-zinc alloy electroplated coatings are recognized as a potential alternative to toxic cadmium as corrosion resistant deposits because they combine the barrier protection of tin with the cathodic protection afforded by zinc. The coatings containing 20 wt.% zinc, balance tin, offer excellent corrosion protection for steel and do not form gross voluminous white corrosion products like pure zinc or high zinc alloy deposits. In this study, the effects of variables of the process (i.e. cathodic current density, pH and temperature) on deposit composition have been evaluated using a Hull cell to obtain 20 wt.% zinc alloy coatings. The tin-20 wt.% zinc deposits, produced with electroplating optimized conditions, were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray fluorescence spectrometry (XRF) and glow discharge optical emission spectrometry (GDOES). On the other hand, the corrosion behaviour of tin-zinc alloy electroplated coatings on steel has been investigated using electrochemical methods in a 3 wt.% NaCl solution and the salt spray test. The performance of the deposits was compared with cadmium and zinc-nickel electrodeposited coatings. The results show that the corrosion resistance of tin-20 wt.% zinc alloy coating is superior to that of cadmium and zinc-12 wt.% nickel coatings. Finally, sliding friction tests were conducted.

  7. Electrochemical deposition of Mg(OH2/GO composite films for corrosion protection of magnesium alloys

    Directory of Open Access Journals (Sweden)

    Fengxia Wu

    2015-09-01

    Full Text Available Mg(OH2/graphene oxide (GO composite film was electrochemical deposited on AZ91D magnesium alloys at constant potential. The characteristics of the Mg(OH2/GO composite film were investigated by scanning electron microscope (SEM, energy-dispersive X-ray spectrometry (EDS, X-ray diffractometer (XRD and Raman spectroscopy. It was shown that the flaky GO randomly distributed in the composite film. Compared with the Mg(OH2 film, the Mg(OH2/GO composite film exhibited more uniform and compact structure. Potentiodynamic polarization tests revealed that the Mg(OH2/GO composite film could significantly improve the corrosion resistance of Mg(OH2 film with an obvious positive shift of corrosion potential by 0.19 V and a dramatic reduction of corrosion current density by more than one order of magnitude.

  8. Passive behaviour of alloy corrosion-resistant steel Cr10Mo1 in simulating concrete pore solutions with different pH

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Zhiyong, E-mail: 230139452@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Jiang, Jinyang, E-mail: jiangjinyang16@163.com [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Sun, Wei, E-mail: sunwei@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Song, Dan, E-mail: songdancharls@hhu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); College of Mechanics and Materials, Hohai University, Nanjing 210098, Jiangsu (China); Ma, Han, E-mail: mahan-iris@shasteel.cn [Research Institute of Jiangsu Shasteel Iron and Steel, Zhangjiagang 215625, Jiangsu (China); Zhang, Jianchun, E-mail: Zhangjc-iris@shasteel.cn [Research Institute of Jiangsu Shasteel Iron and Steel, Zhangjiagang 215625, Jiangsu (China); Wang, Danqian, E-mail: wonderbaba@126.com [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China)

    2016-12-15

    Highlights: • A new alloy corrosion-resistant steel Cr10Mo1 is developed for reinforcing rebar of concrete in severe environments. • The effects of pH on the passive behaviour of Cr10Mo1 steel compared with plain carbon steel were studied systematically by electrochemical techniques and surface analysis. • The mechanism for self-reinforcing passivity against carbonation of the corrosion-resistant steel is revealed. - Abstract: The passive behaviour of new alloy corrosion-resistant steel Cr10Mo1 and plain carbon steel (as a comparison) in simulating concrete pore solutions of different pH (ranging from 13.5 to 9.0) under open circuit potential conditions, was evaluated by various electrochemical techniques: potentiodynamic polarization, capacitance measurements and electrochemical impedance spectroscopy. The chemical composition and structure of passive films were investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The electrochemical responses of passive films show that Cr10Mo1 steel has an increasing passivity with pH decreasing while carbon steel dose conversely, revealing carbonation does no negative effect on passivation of the corrosion-resistant steel. SIMS reveals that the passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer mainly consisting of Fe oxides and hydroxides, and an inner layer enriched in Cr species, while only a Fe-concentrated layer for carbon steel. According to the XPS analysis results, as the pH decreases, more stable and protective Cr oxides are enriched in the film on Cr10Mo1 steel while Fe oxides gradually decompose. Higher content of Cr oxides in the film layer provides Cr10Mo1 corrosion-resistant steel more excellent passivity at lower pH.

  9. ELECTROCHEMICAL BEHAVIOUR OF METHYLENE BLUE IN NON-AQUEOUS SOLVENTS

    International Nuclear Information System (INIS)

    Caram, J.A.; Suárez, J.F. Martínez; Gennaro, A.M.; Mirífico, M.V.

    2015-01-01

    Graphical abstract: Display Omitted - Highlights: • The dye is electro-reduced in two separated monoelectronic charge transfers. • Solvent/supporting electrolyte/acid/base modifies the electrochemical parameters. • A dissociation equilibrium of the dye in non-aqueous solvent is proposed. • The electro-generated and stable dye-radical is also chemically produced in EDA or KOH/DMF. • A new species is reversibly formed in KOH/EtOH or ACN. - Abstract: The electrochemical behaviour of methylene blue in solution of non-aqueous solvents with different supporting electrolytes was studied by cyclic voltammetry. Dye electro-reduction presents two well-defined processes of monoelectronic charge transfer yielding a free radical in the first process and an anion in the second electron transfer. Free radical and anion are long living species in some of the studied media. Effects of supporting electrolyte and solvent on the peak potentials, the peak current functions and the reversibility of the charge transfer processes are reported. A dissociation equilibrium of the dye in solution of non-aqueous solvents and the acid or base added determine markedly the electrochemical responses. In the particular cases of KOH/DMF or EDA basic media the chemical formation of the stable methylene blue radical was detected and it was characterized by EPR spectroscopy. A general reaction scheme is proposed

  10. In situ corrosion measurements by electrochemical method (IC experiment) at Mont Terri

    International Nuclear Information System (INIS)

    Dewonck, S.; Bataillon, C.; Crusset, D.; Schwyn, B.; Nakayama, N.; Kwong, G.

    2010-01-01

    Document available in extended abstract form only. The study of the interactions of steel pieces with an argillaceous rock is the aim of the IC experiment carried out in the Mont Terri Rock Laboratory (Switzerland). More precisely, the IC experiment consists in monitoring the corrosion rate of various steel (Inconel 690, 316L stainless steel, 2 carbon steels one representative of Andra concept and another of Nagra concept) at 80 deg. C, in anaerobic condition, in contact with the Opalinus clay formation. The corrosion rate monitoring is based on Electrochemical Impedance Spectroscopy (EIS). This method is not disturbing for the corrosion process i.e. the corrosion rate doesn't change during the electrochemical measurement. The main drawback of this method is that the corrosion process must be in stationary or quasi stationary state: EIS can only measure corrosion rates which do not change quickly with time. This method is well adapted for long term corrosion monitoring because long term corrosion rate evolves slowly. A special design of the experimental setup was developed to allow optimal interactions between rock and steel samples. It consists in mounting the steel samples inside of a bore-core section. This section is then placed at the extremity of the borehole equipment. The equipment is inserted in a vertical descending borehole and sealed by a large packer. Another particularity of the experimental setup is the possibility of heating the experimental section up to 80 deg. C. Finally, the equipment was built in such a way that such that it will be retrievable from the borehole after several years of experiment, in order to perform further analyses on the reacting materials (core and steel samples). A circulation loop links the experimental interval to the sampling, measuring various parameters (pH, Eh, electrical conductivity, dissolved oxygen and hydrogen) and control equipment installed in a cabinet, in the gallery of the underground laboratory. At the

  11. Corrosion behaviour of stainless steel in contact with wine and beer

    Directory of Open Access Journals (Sweden)

    V. Alar

    2016-07-01

    Full Text Available The effects of wine and beer on the corrosion behavior of AISI 304, AISI 316 and AIS 316Ti were investigated using the electrochemical and gravimetric methods. Physical and chemical parameters of wine and beer were determined before and after the immersion of the steel plates. The corrosion behavior of materials was evaluated using the conducting cyclic potentiodynamic polarization measurements for localized corrosion. The corrosion potential (Ecorr, and the pitting potential (Epit were determined through the application of the cyclic polarization method. Changes caused in the values of the roughness parameter Ra by immersing the samples into electrolytes were also studied.

  12. Correction: Electrochemical Investigation of the Corrosion of Different Microstructural Phases of X65 Pipeline Steel under Saturated Carbon Dioxide Conditions. Materials 2015, 8, 2635–2649

    Directory of Open Access Journals (Sweden)

    Yuanfeng Yang

    2015-12-01

    Full Text Available In the published manuscript “Electrochemical Investigation of the Corrosion of Different Microstructural Phases of X65 Pipeline Steel under Saturated Carbon Dioxide Conditions. [...

  13. Development of Advanced Electrochemical Emission Spectroscopy for Monitoring Corrosion in Simulated DOE Liquid Waste

    Energy Technology Data Exchange (ETDEWEB)

    Digby Macdonald; Brian Marx; Balaji Soundararajan; Morgan Smith

    2005-07-28

    The different tasks that have been carried out under the current program are as follows: (1) Theoretical and experimental assessment of general corrosion of iron/steel in borate buffer solutions by using electrochemical impedance spectroscopy (EIS), ellipsometry and XPS techniques; (2) Development of a damage function analysis (DFA), which would help in predicting the accumulation of damage due to pitting corrosion in an environment prototypical of DOE liquid waste systems; (3) Experimental measurement of crack growth rate, acoustic emission signals, and coupling currents for fracture in carbon and low alloy steels as functions of mechanical (stress intensity), chemical (conductivity), electrochemical (corrosion potential, ECP), and microstructural (grain size, precipitate size, etc) variables in a systematic manner, with particular attention being focused on the structure of the noise in the current and its correlation with the acoustic emissions; (4) Development of fracture mechanisms for carbon and low alloy steels that are consistent with the crack growth rate, coupling current data and acoustic emissions; (5) Inserting advanced crack growth rate models for SCC into existing deterministic codes for predicting the evolution of corrosion damage in DOE liquid waste storage tanks; (6) Computer simulation of the anodic and cathodic activity on the surface of the steel samples in order to exactly predict the corrosion mechanisms; (7) Wavelet analysis of EC noise data from steel samples undergoing corrosion in an environment similar to that of the high level waste storage containers, to extract data pertaining to general, pitting and stress corrosion processes, from the overall data. The work has yielded a number of important findings, including an unequivocal demonstration of the role of chloride ion in passivity breakdown on nickel in terms of cation vacancy generation within the passive film, the first detection and characterization of individual micro fracture

  14. Electrochemical Impedance and Polarization Corrosion Studies of Tantalum Surface Modified by DC Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Maciej Sowa

    2018-04-01

    Full Text Available Tantalum has recently become an actively researched biomaterial for the bone reconstruction applications because of its excellent corrosion resistance and successful clinical records. However, a bare Ta surface is not capable of directly bonding to the bone upon implantation and requires some method of bioactivation. In this study, this was realized by direct current (DC plasma electrolytic oxidation (PEO. Susceptibility to corrosion is a major factor determining the service-life of an implant. Therefore, herein, the corrosion resistance of the PEO coatings on Ta was investigated in Ringer’s solution. The coatings were formed by galvanostatic anodization up to 200, 300 and 400 V, after which the treatment was conducted potentiostatically until the total process time amounted to 5 min. Three solutions containing Ca(H2PO22, Ca(HCOO2 and Mg(CH3COO2 were used in the treatment. For the corrosion characterization, electrochemical impedance spectroscopy and potentiodynamic polarization techniques were chosen. The coatings showed the best corrosion resistance at voltages low enough so that the intensive sparking was absent, which resulted in the formation of thin films. The impedance data were fitted to the equivalent electrical circuits with two time constants, namely R(Q[R(QR] and R(Q[R(Q[RW

  15. Flow-induced corrosion of absorbable magnesium alloy: In-situ and real-time electrochemical study

    Science.gov (United States)

    Wang, Juan; Jang, Yongseok; Wan, Guojiang; Giridharan, Venkataraman; Song, Guang-Ling; Xu, Zhigang; Koo, Youngmi; Qi, Pengkai; Sankar, Jagannathan; Huang, Nan; Yun, Yeoheung

    2016-01-01

    An in-situ and real-time electrochemical study in a vascular bioreactor was designed to analyze corrosion mechanism of magnesium alloy (MgZnCa) under mimetic hydrodynamic conditions. Effect of hydrodynamics on corrosion kinetics, types, rates and products was analyzed. Flow-induced shear stress (FISS) accelerated mass and electron transfer, leading to an increase in uniform and localized corrosions. FISS increased the thickness of uniform corrosion layer, but filiform corrosion decreased this layer resistance at high FISS conditions. FISS also increased the removal rate of localized corrosion products. Impedance-estimated and linear polarization-measured polarization resistances provided a consistent correlation to corrosion rate calculated by computed tomography. PMID:28626241

  16. Corrosion behaviour of austenitic stainless steel, nickel-base alloy and its weldments in aqueous LiBr solutions

    Energy Technology Data Exchange (ETDEWEB)

    Blasco-Tamarit, E.; Igual-Munoz, A.; Garcia Anton, J.; Garcia-Garcia, D. [Departamento de Ingenieria Quimica y Nuclear. E.T.S.I.Industriales, Universidad Politecnica de Valencia, P.O. Box 22012 E-46071 Valencia (Spain)

    2004-07-01

    With the advances in materials production new alloys have been developed, such as High- Alloy Austenitic Stainless Steels and Nickel-base alloys, with high corrosion resistance. These new alloys are finding applications in Lithium Bromide absorption refrigeration systems, because LiBr is a corrosive medium which can cause serious corrosion problems, in spite of its favourable properties as absorbent. The objective of the present work was to study the corrosion resistance of a highly alloyed austenitic stainless steel (UNS N08031) used as base metal, a Nickel-base alloy (UNS N06059) used as its corresponding filler metal, and the weld metal obtained by the Gas Tungsten Arc Welding (GTAW) procedure. The materials have been tested in different LiBr solutions (400 g/l, 700 g/l, 850 g/l and a commercial 850 g/l LiBr heavy brine containing Lithium Chromate as corrosion inhibitor), at 25 deg. C. Open Circuit Potential tests and potentiodynamic anodic polarization curves have been carried out to obtain information about the general electrochemical behaviour of the materials. The polarization curves of all the alloys tested were typical of passivable materials. Pitting corrosion susceptibility has been evaluated by means of cyclic potentiodynamic curves, which provide parameters to analyse re-passivation properties. The galvanic corrosion generated by the electrical contact between the welded and the base material has been estimated from the polarization diagrams according to the Mixed Potential Method. Samples have been etched to study the microstructure by Scanning Electron Microscopy (SEM). The results demonstrate that the pitting resistance of all these materials increases as the LiBr concentration decreases. In general, the presence of chromate tended to shift the pitting potential to more positive values than those obtained in the 850 g/l LiBr solution. (authors)

  17. Electrochemical techniques application in corrosion problems of fossil power plants; Aplicacion de tecnicas electroquimicas en problemas de corrosion en centrales termoelectricas

    Energy Technology Data Exchange (ETDEWEB)

    Cano Castillo, Ulises; Garcia Ochoa, Esteban Miguel; Martinez Villafane, Alberto; Mariaca Rodriguez, Liboria; Malo Tamayo, Jose Maria; Uruchurtu Chavarin, Jorge [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1990-12-31

    Some aspects of the electrochemical techniques employed to evaluate the corrosion at low temperature in fossil power plants are commented, as well as the results obtained with the application of them in three power plants of this type. [Espanol] Se comentan algunos aspectos de tecnicas electroquimicas utilizadas para evaluar la corrosion en baja temperatura en centrales termoelectricas, asi como los resultados de la aplicacion de las mismas en tres centrales de este tipo.

  18. Electrochemical behavior of tube-fin assembly for an aluminum automotive condenser with improved corrosion resistance

    Directory of Open Access Journals (Sweden)

    M.A. Pech-Canul

    Full Text Available An aluminum automotive condenser was designed to exhibit high corrosion resistance in the seawater acetic acid test (SWAAT combining zinc coated microchannel tubes and fins made with AA4343/AA3003(Zn/AA4343 brazing sheet. Electrochemical measurements in SWAAT solution were carried out under laboratory conditions using tube-fin assembly and individual fin and tube samples withdrawn from the condenser core. The aim was to gain information on the protective role of the zinc sacrificial layer and about changes in corrosion behavior as a function of immersion time. External corrosion of the tube-fin system was simulated by immersion of mini-core samples under open circuit conditions. The corrosion rate increased rapidly during the first 6 h and slowly afterwards. The short time behavior was related to the dissolution of the oxide film and fast dissolution of the outermost part of the zinc diffusion layer. With the aid of cross-sectional depth corrosion potential profiles, it was shown that as the sacrificial layer gets dissolved, the surface concentration of zinc decreases and the potential shifts to less negative values. The results of galvanic coupling of tube and fins in a mini-cell showed that the tube became the anode while the fins exhibited cathodic behavior. An evolution in the galvanic interaction was observed, due to the progressive dissolution of the sacrificial zinc layer. The difference of uncoupled potentials between tube and fins decreased from 71 mV to 32 mV after 84 h of galvanic coupling. At the end of such period there was still a part of the zinc sacrificial layer remaining which would serve for protection of the tube material for even longer periods and there were indications of slight corrosion in the fins. Keywords: Aluminum, Automotive, Corrosion, Galvanic, Zn coating

  19. Chemical passivation as a method of improving the electrochemical corrosion resistance of Co-Cr-based dental alloy.

    Science.gov (United States)

    Rylska, Dorota; Sokołowski, Grzegorz; Sokołowski, Jerzy; Łukomska-Szymańska, Monika

    2017-01-01

    The purpose of the study was to evaluate corrosion resistance of Wirobond C® alloy after chemical passivation treatment. The alloy surface undergone chemical passivation treatment in four different media. Corrosion studies were carried out by means of electrochemical methods in saline solution. Corrosion effects were determined using SEM. The greatest increase in the alloy polarization resistance was observed for passive layer produced in Na2SO4 solution with graphite. The same layer caused the highest increase in corrosion current. Generally speaking, the alloy passivation in Na2SO4 solution with graphite caused a substantial improvement of the corrosion resistance. The sample after passivation in Na2SO4 solution without graphite, contrary to others, lost its protective properties along with successive anodic polarization cycles. The alloy passivation in Na3PO4 solution with graphite was the only one that caused a decrease in the alloy corrosion properties. The SEM studies of all samples after chemical passivation revealed no pit corrosion - in contrast to the sample without any modification. Every successive polarization cycle in anodic direction of pure Wirobond C® alloy enhances corrosion resistance shifting corrosion potential in the positive direction and decreasing corrosion current value. The chemical passivation in solutions with low pH values decreases susceptibility to electrochemical corrosion of Co-Cr dental alloy. The best protection against corrosion was obtained after chemical passivation of Wirobond C® in Na2SO4 solution with graphite. Passivation with Na2SO4 in solution of high pH does not cause an increase in corrosion resistance of WIROBOND C. Passivation process increases alloy resistance to pit corrosion.

  20. Imposed potential measurement to evaluate the pitting corrosion resistance and the galvanic behaviour of a highly alloyed austenitic stainless steel and its weldment in a LiBr solution at temperatures up to 150ºC

    OpenAIRE

    Blasco Tamarit, María Encarnación; García García, Dionisio Miguel; García Antón, José

    2011-01-01

    Pitting corrosion resistance and galvanic behaviour of Alloy 31, a highly alloyed austenitic stainless steel (UNS N08031), and its weldment were studied in a heavy brine LiBr solution 1080 g/l at different temperatures (75–150 °C) using electrochemical techniques. The Mixed Potential Theory was used to evaluate the galvanic corrosion between the base and welded metals. Cyclic potentiodynamic curves indicate that high temperatures make passivation and repassivation of pits difficult, because t...

  1. The effect of discontinuities on the corrosion behaviour of copper canisters

    International Nuclear Information System (INIS)

    King, F.

    2004-03-01

    Discontinuities may remain in the weld region of copper canisters following the final closure welding and inspection procedures. Although the shell of the copper canister is expected to exhibit excellent corrosion properties in the repository environment, the question remains what impact these discontinuities might have on the long-term performance and service life of the canister. A review of the relevant corrosion literature has been carried out and an expert opinion of the impact of these discontinuities on the canister lifetime has been developed. Since the amount of oxidant in the repository is limited and the maximum wall penetration is expected to be 2 O/Cu(OH) 2 film at a critical electrochemical potential determines where and when pits initiate, not the presence of pit-shaped surface discontinuities. The factors controlling pit growth and death are well understood. There is evidence for a maximum pit radius for copper in chloride solutions, above which the small anodic: cathodic surface area ratio required for the formation of deep pits cannot be sustained. This maximum pit radius is of the order of 0.1-0.5 mm. Surface discontinuities larger than this size are unlikely to propagate as pits, and pits generated from smaller discontinuities will die once they reach this maximum size. Death of propagating pits will be compounded by the decrease in oxygen flux to the canister as the repository environment becomes anoxic. Surface discontinuities could impact the SCC behaviour either through their effect on the local environment or via stress concentration or intensification. There is no evidence that surface discontinuities will affect the initiation of SCC by ennoblement of the corrosion potential or the formation of locally aggressive conditions. Stress concentration at pits could lead to crack initiation under some circumstances, but the stress intensity factor for the resultant cracks, or for pre-existing crack-like discontinuities, will be smaller than the

  2. Effect of ageing time and temperature on corrosion behaviour of aluminum alloy 2014

    Science.gov (United States)

    Gadpale, Vikas; Banjare, Pragya N.; Manoj, Manoranjan Kumar

    2018-03-01

    In this paper, the effect of corrosion behaviour of aluminium alloy 2014 were studied by potentiodynamic polarization in 1 mole of NaCl solution of aged sample. The experimental testing results concluded that, corrosion resistance of Aluminum alloy 2014 degraded with the increasing the temperature (150°C & 200°C) and time of ageing. Corroded surface of the aged specimens was tested under optical microscopes for microstructures for phase analysis. Optical micrographs of corroded surfaces showed general corrosion and pitting corrosion. The corrosion resistance of lower ageing temperature and lower ageing time is higher because of its fine distribution of precipitates in matrix phase.

  3. Electrochemical corrosion of carbon steels in H2S-containing brines

    Science.gov (United States)

    Feng, Ruishu

    The electrochemical corrosion behaviors of high strength low alloy carbon steel, Grade S-135, and ultra-high strength low alloy carbon steel, Grade UD-165, were investigated in alkaline brines at pH of 7.9, 10.7, and 12.4 and four H2S partial pressures (P H2S) from 0 to 69 kPa at 85 °C using in situ electrochemical measurements, ex situ surface analyses, and software modeling. HS-(aq) was calculated to be the dominant sulfide species from pH 7.9 to 12.4. After 60 hours, polarization resistance (Rpol) of S-135 and UD-165 generally increased as pH increased at lower PH2S (0 and 0.83 kPa), whereas Rpol decreased and then increased as pH increased at higher PH2S (8.3 and 69 kPa). At each pH, the lower PH2S increased Rpol or did not significantly change R pol, whereas the higher PH2S decreased Rpol. Two opposite effects from H2S were proposed, an accelerating effect due to H2S(aq) and HS-(aq) facilitating the Faradaic reactions and the localized corrosion, and an inhibiting effect due to the protectiveness of the corrosion products. The inhibiting effect was often observed at relatively low H2S concentrations at pH 7.9 and 12.4. The electrochemical impedance did not change significantly at different stir rates for both S-135 and UD-165, indicating that mass transport in the bulk solution was not the rate determining step. The corrosion products generally changed from iron carbonate and sulfides to iron oxide as pH increased, which agreed with the Pourbaix diagrams. Solution pH in the three solutions were calculated to be 8.1, 9.8, and 10.8 at 200 °C, respectively. Polarization resistance values of UD-165 at 200 °C were consistently one to two orders of magnitude lower than at 85 °C, which corresponded to a drastic increase in corrosion rate at elevated temperature. At 200 °C, Rpol at 9.8 was the smallest after 60 hours among the three solutions. The modeled results were in reasonable agreement with the experimental CR values within a factor of 4. A new method

  4. Investigations of the corrosion behaviour of the Si-containing stainless steel 1.4361 with combined surface analysis, electrochemistry and radionuclide technique

    International Nuclear Information System (INIS)

    Maar-Stumm, M.

    1990-03-01

    The present work aimed at detailed information on the corrosion behaviour and particularly the corrosion mechanism of the steel 1.4361 in concentrated nitric acid by use of a combination of electrochemical methods, radionuclide technique and surface analysis. For comparison steel samples corroded by other methods were investigated by surface analysis, too. At the beginning of the corrosion in nitric acid Fe and Ni are dissolved preferentially. Cr and Si are enriched in the surface region. A primary corrosion layer is formed which is equivalent to the oxidic overlayer of atmospherically oxidized samples. It consists of the oxides of chromium and iron mixed up with glass-like SiO 2 . Ni does not contribute to the formation of the oxidic overlayer. On top of this primary corrosion layer there is an isolating gel-like SiO 2 -layer with a thickness depending on strength and duration of the corrosive attack. Its mechanical stability decreases with increasing layer thickness. At the boundary to the primary corrosion layer this gel-like SiO 2 -layer is closed, mechanically stable and conducting. Samples corroded under the standardized conditions of the Huey-test show a similar structure of the overlayer with the exception that the primary corrosion layer consists only of glass-like SiO 2 . The combination of several methods revealed detailed information about mass loss and structure of the overlayer at different electrode potentials. (orig./MM) [de

  5. Corrosion protection aspects of electrochemically synthesized poly(o-anisidine-co-o-toluidine) coatings on copper

    Energy Technology Data Exchange (ETDEWEB)

    Pawar, Pritee [Department of Physics, North Maharashtra University, Jalgaon 425001, Maharashtra (India); Gaikwad, A.B. [Center for Materials Characterization, National Chemical Laboratory, Pashan, Pune 411008, Maharashtra (India); Patil, P.P. [Department of Physics, North Maharashtra University, Jalgaon 425001, Maharashtra (India)]. E-mail: pnmu@yahoo.co.in

    2007-05-25

    The poly(o-anisidine-co-o-toluidine) coatings were synthesized on copper substrates by electrochemical copolymerization of o-anisidine with o-toluidine using sodium salicylate as supporting electrolyte. These coatings were characterized by cyclic voltammetry, UV-vis absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and scanning electron microscopy (SEM). The formation of the copolymer with the mixture of monomers in the aqueous sodium salicylate solution was ascertained by a critical comparison of the results obtained with the polymerization of the individual monomers, o-anisidine and o-toluidine, respectively. The corrosion protection aspects of poly(o-anisidine-co-o-toluidine) coatings to copper was investigated in aqueous 3% NaCl solution by potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). The results of the potentiodynamic polarization measurements and EIS studies showed that the poly(o-anisidine-co-o-toluidine) coatings provided the effective corrosion protection to copper than that of respective homopolymers. The corrosion rate is observed to depend on the feed ratio of o-toluidine used for the synthesis of the copolymer coatings.

  6. Electrochemical corrosion of lanthanum chromite and yttrium chromite in coal slag

    Energy Technology Data Exchange (ETDEWEB)

    Marchant, D.D.; Bates, J.L.

    1981-01-01

    Lanthanum chromites have long been considered as electrodes for magnetohydrodynamic (MHD) generator channels. These chromites, when doped with divalent ions such as Ca, Mg or Sr, have adequate electronic and electrical conductivity (2), and melting points greater than 2500/sup 0/K. However, above approx. 1850/sup 0/K, selective vapor loss of chromium results in the formation of a La/sub 2/O/sub 3/ phase. The La/sub 2/O/sub 3/ is hydroscopic at room temperature, resulting in a large volume change and loss of mechanical integrity when exposed to H/sub 2/O. The analogous yttrium chromites have thermal and electrical properties similar to that for the lanthanum chromites. Although vapor loss of Cr results in the formation of Y/sub 2/O/sub 3/, this oxide does not hydrate. Corrosion studies of yttrium chromite compositions show that doped YCrO/sub 3/ may be a viable MHD electrode. An electrochemical corrosion study of both magnesium-doped lanthanum and yttrium chromites in synthetic coal slag electrolytes is described. Possible chemical and electrochemical degradation phenomena, as well as the relative rates of corrosion are emphasized.

  7. Electrochemical Corrosion Behavior of Oxidation Layer on Fe30Mn5Al Alloy

    Directory of Open Access Journals (Sweden)

    ZHU Xue-mei

    2017-08-01

    Full Text Available The Fe30Mn5Al alloy was oxidized at 800℃ in air for 160h, the oxidation-induced layer about 15μm thick near the scale-metal interface was induced to transform to ferrite and become enriched in Fe and depletion in Mn. The effect of the oxidation-induced Mn depletion layer on the electrochemical corrosion behavior of Fe30Mn5Al alloy was evaluated. The results show that in 1mol·L-1 Na2SO4 solution, the anodic polarization curve of the Mn depletion layer exhibits self-passivation, compared with Fe30Mn5Al austenitic alloy, and the corrosion potential Evs SCE is increased to -130mV from -750mV and the passive current density ip is decreased to 29μA/cm2 from 310μA/cm2. The electrochemical impedance spectroscopy(EIS of the Mn depletion layer has the larger diameter of capacitive arc, the higher impedance modulus|Z|, and the wider phase degree range, and the fitted polarization resistant Rt is increased to 9.9kΩ·cm2 from 2.7kΩ·cm2 by using an equivalent electric circuit of Rs-(Rt//CPE. The high insulation of the Mn depletion layer leads to an improved corrosion resistance of Fe30Mn5Al austenitic alloy.

  8. Electrochemical behaviour and structure of rust formed on Si- and Al-bearing steel after atmospheric exposure

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, T., E-mail: nishimura.toshiyasu@nims.go.j [National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2010-11-15

    Research highlights: {yields} The nano structure of the rust was shown by TEM-EELS {yields} The electrochemistry rusted steel was demonstrated by EIS {yields} The nano complex oxides containing Si and Al in inner rust increased the corrosion resistance - Abstract: The corrosion resistance of Si- and Al-bearing steel was estimated by atmospheric exposure test, and the structure of the rust was examined by EPMA (electroprobe X-ray microanalysis) and TEM (transmission electron microscopy) analysis. Moreover, the electrochemical behaviour of rust was investigated by EIS (electrochemical impedance spectroscopy). The Si- and Al-bearing steel exhibited excellent corrosion resistance in the exposure test as compared with carbon steel (SM). EPMA and TEM analysis showed that Si and Al mainly existed in nanoscale iron complex oxides in the inner rust formed on this steel. The Al K spectrum of the rust exhibited a peak that was the same as that of Al{sub 2}O{sub 3} in the EPMA and TEM-EELS (electron energy loss spectroscopy) analysis. This result suggests that Al was present in the complex oxides as Al{sup 3+}. In the same way, Si was identified as being in an intermediate state in the complex oxides of the inner rust. EIS measurement of the exposure test samples revealed much higher rust resistance (R{sub rust}) and corrosion reaction resistance (R{sub t}) of Si- and Al-bearing steel compared to that of SM. Finally, it was found that nanoscale complex iron oxides formed in the inner rust of Si- and Al-bearing steel, resulting in increased R{sub rust} and R{sub t}, and corrosion suppression.

  9. Electrochemical techniques implementation for corrosion rate measurement in function of humidity level in grounding systems (copper and stainless steel) in soil samples from Tunja (Colombia)

    Science.gov (United States)

    Salas, Y.; Guerrero, L.; Blanco, J.; Jimenez, C.; Vera-Monroy, S. P.; Mejía-Camacho, A.

    2017-12-01

    In this work, DC electrochemical techniques were used to determine the corrosion rate of copper and stainless-steel electrodes used in grounding, varying the level of humidity, in sandy loam and clay loam soils. The maximum corrosion potentials were: for copper -211 and -236mV and for stainless steel of -252 and -281mV, in sandy loam and clay loam respectively, showing that in sandy loam the values are higher, about 30mV. The mechanism by which steel controls corrosion is by diffusion, whereas in copper it is carried out by transfer of mass and charge, which affects the rate of corrosion, which in copper reached a maximum value of 5mm/yr and in Steel 0.8mm/yr, determined by Tafel approximations. The behaviour of the corrosion rate was mathematically adjusted to an asymptotic model that faithfully explains the C.R. as a function of humidity, however, it is necessary to define the relation between the factor □ established in the model and the precise characteristics of the soil, such as the permeability or quantity of ions present.

  10. Local electrochemical behaviour of 7xxx aluminium alloys

    NARCIS (Netherlands)

    Andreatta, F.

    2004-01-01

    Aluminium alloys of the 7xxx series (Al-Zn-Mg-Cu) are susceptible to localized types of corrosion like pitting, intergranular corrosion and exfoliation corrosion. This represents a limitation for the application of these alloys in the aerospace components because localized corrosion might have a

  11. Corrosion Behavior of Surface-Treated Implant Ti-6Al-4V by Electrochemical Polarization and Impedance Studies

    Science.gov (United States)

    Paul, Subir; Yadav, Kasturi

    2011-04-01

    Implant materials for orthopedic and heart surgical services demand a better corrosion resistance material than the presently used titanium alloys, where protective oxide layer breaks down on a prolonged stay in aqueous physiological human body, giving rise to localized corrosion of pitting, crevice, and fretting corrosion. A few surface treatments on Ti alloy, in the form of anodization, passivation, and thermal oxidation, followed by soaking in Hank solution have been found to be very effective in bringing down the corrosion rate as well as producing high corrosion resistance surface film as reflected from electrochemical polarization, cyclic polarization, and Electrochemical Impedance Spectroscopy (EIS) studies. The XRD study revealed the presence of various types of oxides along with anatase and rutile on the surface, giving rise to high corrosion resistance film. While surface treatment of passivation and thermal oxidation could reduce the corrosion rate by 1/5th, anodization in 0.3 M phosphoric acid at 16 V versus stainless steel cathode drastically brought down the corrosion rate by less than ten times. The mechanism of corrosion behavior and formation of different surface films is better understood from the determination of EIS parameters derived from the best-fit equivalent circuit.

  12. Corrosion behaviour of Nd-Fe-B magnets containing Co and Cr

    International Nuclear Information System (INIS)

    Pawlowska, G.; Bala, H.; Szymura, S.

    1993-01-01

    The effect of partial substitution of iron by Co and Cr on corrosion behaviour of Nd 16 Fe 76 B 8 permanent magnets has been investigated. Small additions of Cr (1 to 4%at) are enough to ensure maximal corrosion inhibition. Greater amount of Cr into Nd-Fe-B alloy (>8%at), against expectations, practically do not affect the corrosion behaviour and additionally, considerably worsen its magnetic properties. Corrosion tests have shown a distinct effect of cobalt addition on the inhibition of both acid corrosion and the abnormal dissolution process of the Nd-Fe-Co-B magnets. Cobalt additions inhibit the atmosphere corrosion of Nd-Fe-B permanent magnets, especially a salt-spray environment. (author). 6 refs, 4 figs, 1 tab

  13. Biocompatibility and Corrosion Protection Behaviour of Hydroxyapatite Sol-Gel-Derived Coatings on Ti6Al4V Alloy.

    Science.gov (United States)

    El Hadad, Amir A; Peón, Eduardo; García-Galván, Federico R; Barranco, Violeta; Parra, Juan; Jiménez-Morales, Antonia; Galván, Juan Carlos

    2017-01-24

    The aim of this work was to prepare hydroxyapatite coatings (HAp) by a sol-gel method on Ti6Al4V alloy and to study the bioactivity, biocompatibility and corrosion protection behaviour of these coatings in presence of simulated body fluids (SBFs). Thermogravimetric/Differential Thermal Analyses (TG/DTA) and X-ray Diffraction (XRD) have been applied to obtain information about the phase transformations, mass loss, identification of the phases developed, crystallite size and degree of crystallinity of the obtained HAp powders. Fourier Transformer Infrared Spectroscopy (FTIR) has been utilized for studying the functional groups of the prepared structures. The surface morphology of the resulting HAp coatings was studied by Scanning Electron Microscopy (SEM). The bioactivity was evaluated by soaking the HAp-coatings/Ti6Al4V system in Kokubo's Simulated Body Fluid (SBF) applying Inductively Coupled Plasma (ICP) spectrometry. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and Alamar blue cell viability assays were used to study the biocompatibility. Finally, the corrosion behaviour of HAp-coatings/Ti6Al4V system was researched by means of Electrochemical Impedance Spectroscopy (EIS). The obtained results showed that the prepared powders were nanocrystalline HAp with little deviations from that present in the human bone. All the prepared HAp coatings deposited on Ti6Al4V showed well-behaved biocompatibility, good bioactivity and corrosion protection properties.

  14. Biocompatibility and Corrosion Protection Behaviour of Hydroxyapatite Sol-Gel-Derived Coatings on Ti6Al4V Alloy

    Directory of Open Access Journals (Sweden)

    Amir A. El Hadad

    2017-01-01

    Full Text Available The aim of this work was to prepare hydroxyapatite coatings (HAp by a sol-gel method on Ti6Al4V alloy and to study the bioactivity, biocompatibility and corrosion protection behaviour of these coatings in presence of simulated body fluids (SBFs. Thermogravimetric/Differential Thermal Analyses (TG/DTA and X-ray Diffraction (XRD have been applied to obtain information about the phase transformations, mass loss, identification of the phases developed, crystallite size and degree of crystallinity of the obtained HAp powders. Fourier Transformer Infrared Spectroscopy (FTIR has been utilized for studying the functional groups of the prepared structures. The surface morphology of the resulting HAp coatings was studied by Scanning Electron Microscopy (SEM. The bioactivity was evaluated by soaking the HAp-coatings/Ti6Al4V system in Kokubo’s Simulated Body Fluid (SBF applying Inductively Coupled Plasma (ICP spectrometry. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT and Alamar blue cell viability assays were used to study the biocompatibility. Finally, the corrosion behaviour of HAp-coatings/Ti6Al4V system was researched by means of Electrochemical Impedance Spectroscopy (EIS. The obtained results showed that the prepared powders were nanocrystalline HAp with little deviations from that present in the human bone. All the prepared HAp coatings deposited on Ti6Al4V showed well-behaved biocompatibility, good bioactivity and corrosion protection properties.

  15. Electrochemical Study of Welded AISI 304 and 904L Stainless Steel in Seawater in View of Corrosion

    OpenAIRE

    Richárd Székely; Réka Répánszki; András Somogyi; Ákos Horváth; János Dobránszki

    2010-01-01

    This is a comparative study of the corrosion behaviour of welds in AISI 304 and AISI 904L stainless steels carried out in seawater model solution in the temperature range 5-35°C and the standard of corrosion testing of welds was followed. The corrosion rate and corrosion attack characteristics were determined for welds of the examined steels with several type of treatment. The aim of this work was to compare the steels based on their resistance against the corrosion in terms of pitting potent...

  16. Novel electrochemical approach to study corrosion mechanism of Al-Au wire-bond pad interconnections

    DEFF Research Database (Denmark)

    Elisseeva, O. V.; Bruhn, A.; Cerezo, J.

    2013-01-01

    A gold-aluminium material combination is typically employed as an interconnection for microelectronic devices. One of the reliability risks of such devices is that of corrosion of aluminium bond pads resulting from the galvanic coupling between an aluminium bond pad and a gold wire. The research...... presented in this manuscript focuses on studying bond pad corrosion by selecting an appropriate model system and a dedicated set of electrochemical and analytical experimental tools. Taking into account the complex three-dimensional structure and the small dimensions of Au-Al interconnections (around 50......-100 μm), a dedicated and novel experimental approach was developed. Au-Al covered silicon chips were developed under clean room conditions. Three-dimensional electrodes were mimicked as flat, two-dimensional bond pad model systems, allowing the use of microelectrochemical local probe techniques. Thin...

  17. Electrochemical Study on Newly Synthesized Chlorocurcumin as an Inhibitor for Mild Steel Corrosion in Hydrochloric Acid

    Directory of Open Access Journals (Sweden)

    Ahmed A. Al-Amiery

    2013-11-01

    Full Text Available A new curcumin derivative, i.e., (1E,4Z,6E-5-chloro-1,7-bis(4-hydroxy-3-methoxyphenylhepta-1,4,6-trien-3-one (chlorocurcumin, was prepared starting with the natural compound curcumin. The newly synthesized compound was characterized by elemental analysis and spectral studies (IR, 1H-NMR and 13C-NMR. The corrosion inhibition of mild steel in 1 M HCl by chlorocurcumin has been studied using potentiodynamic polarization (PDP measurements and electrochemical impedance spectroscopy (EIS. The inhibition efficiency increases with the concentration of the inhibitor but decreases with increases in temperature. The potentiodynamic polarization reveals that chlorocurcumin is a mixed-type inhibitor. The kinetic parameters for mild steel corrosion were determined and discussed.

  18. The electrochemical noise (1/f) in the study of the corrosion inhibitor efficiency

    International Nuclear Information System (INIS)

    Bastidas, J.M.; Malo, J.M.

    1985-01-01

    Electrochemical noise (1/f) is associated to the random fluctuation of the current or potential from a corroding metal. In this work, the efficiency of a mixed organic inhibitor in the corrosion of iron in 1N H 2 SO 4 was assessed from the random fluctuation of the corrosion potential. The study was conducted under static and hydrodynamic conditions. The rotating disk electrode was used for the latter. The maximum entropy method (MEM) was used as a spectrum analysis technique. The origin of the potential fluctuations lies in the adsorption of species on the working electrode surface; these species catalyse the charge transfer. Moreover, it is thought that the rate of charge transfer depends on the number of catalytic sites on the electrode surface and on the diffusion of species. (author)

  19. Quantum mechanical and electrochemical investigations on corrosion inhibition properties of novel heterocyclic Schiff bases

    Directory of Open Access Journals (Sweden)

    Nimmy Kuriakose

    2017-07-01

    Full Text Available The corrosion inhibition efficiencies of two novel Schiff bases, namely (E-3-[thiophen-2-ylmethyleneamino]benzoic acid (T2YMABA and (E-4-(5-[(2-phenylhydrazono methyl]thiophen-2-ylbenzoic acid (PHMT2YBA on mild steel (MS in 1.0M HCl solution has been investigated and compared using electrochemical impedance spectroscopy and potentiodynamic polarization analysis. The Schiff bases exhibited very good corrosion inhibitions on mild steel in 1.0M HCl medium and the inhibition efficiency increased with the increase in concentration of the inhibitor. Polarization studies revealed that T2YMABA acted as a mixed type inhibitor whereas PHMT2YBA molecules acted as anodic inhibitor.

  20. Energy Dispersive X-Ray and Electrochemical Impedance Spectroscopies for Performance and Corrosion Analysis of PEMWEs

    Science.gov (United States)

    Steen, S. M., Iii; Zhang, F.-Y.

    2014-11-01

    Proton exchange membrane water electrolyzers (PEMWEs) are a promising energy storage technology due to their high efficiency, compact design, and ability to be used in a renewable energy system. Before they are able to make a large commercial impact, there are several hurdles facing the technology today. Two powerful techniques for both in-situ and ex- situ characterizations to improve upon their performance and better understand their corrosion are electrochemical impedance spectroscopy and energy dispersive x-ray spectroscopy, respectively. In this paper, the authors use both methods in order to characterize the anode gas diffusion layer (GDL) in a PEMWE cell and better understand the corrosion that occurs in the oxygen electrode during electrolysis.

  1. Electrochemical impedance spectroscopy and Surface Studies of Steel Corrosion by Sulphate-Reducing Bacteria

    International Nuclear Information System (INIS)

    Fathul Karim Sahrani; Zaharah Ibrahim; Madzlan Aziz; Adibah Yahya

    2009-01-01

    Sulphate-reducing bacteria (SRB), implicated in microbiologically influenced corrosion were isolated from the deep subsurface at the vicinity of Pasir Gudang, Johor, Malaysia. Electrochemical impedance spectroscopic (EIS) study was carried out to determine the polarization resistance in various types of culturing solutions, with SRB1, SRB2, combination of SRB1 and SRB2 and without SRBs inoculated (control). EIS results showed that in the presence of SRB1, SRB2 and mixed culture SRB1 and SRB2, polarisation resistance values were 7170, 6370 and 7190 ohms respectively compared to that of control, 92400 ohm. X-ray analysis (EDS) of the specimens indicated high sulphur content in the medium containing SRBs. Localized corrosion was observed on the metal surface which was associated with the SRB activity. (author)

  2. Influence of the surface finishing on electrochemical corrosion characteristics of AISI 316L stainless steel

    Directory of Open Access Journals (Sweden)

    Sylvia Dundeková

    2015-05-01

    Full Text Available Stainless steels from 316 group are very often and successfully uses for medical applications where the good mechanical and chemical properties in combination with non-toxicity of the material assure its safe and long term usage. Corrosion properties of AISI 361L stainless steel are strongly influenced by surface roughness and treatment of the engineering parts (specimens and testing temperature. Electrochemical characteristics of ground, mechanically polished and passivated AISI 316L stainless steel specimens were examined with the aim to identify the polarization resistance evolution due to the surface roughness decrease. Results obtained on mechanically prepared specimens where only natural oxide layer created due to the exposure of the material to the corrosion environment was protecting the materials were compared to the passivated specimens with artificial oxide layer. Also the influence of temperature and stabilization time before measurement were taken into account when discussing the obtained results. Positive influence of decreasing surface roughness was obtained as well as increase of polarization resistance due to the chemical passivation of the surface. Increase of the testing temperature and short stabilization time of the specimen in the corrosion environment were observed negatively influencing corrosion resistance of AISI 316L stainless steel.

  3. The electrochemical behavior of steel in concrete and how to evaluate the corrosion rate

    Energy Technology Data Exchange (ETDEWEB)

    Videm, K. [Univ. of Oslo (Norway). Centre for Materials Research; Myrdal, R. [Rescon AS, Sagstua (Norway)

    1996-11-01

    Various electrochemical methods for evaluation of corrosion of steel reinforcement in concrete have been studied and reviewed regarding applicability in the field. Laboratory experiments have been carried out with steel in synthetic pore water and in concrete blocks with chloride additions. The field measurements were performed at a large concrete bridge on the coast. The methods examined are manual potential mapping, automatic measurements of the corrosion potential with embedded reference electrodes, potentiokinetic linear polarization resistance (LPR) measurements with cut reinforcement bars, analysis of the shape of galvanostatic charging curves, and LPR measurements of the reinforcement with a commercial instrument containing a guard ring. The corrosion rates determined with the guard electrode instrument were not in good agreement with estimates based on potential mapping and with result of visual inspection. Due to the high interfacial capacitance of the steel in concrete, potentiokinetic LPR measurements were found to be little suited for determination of the corrosion rate. Good experience was obtained by computer modelling of the galvanostatic charging curve with calculation of the polarization resistance from this type of data. The important advantage of this method is that it is little influenced by the electrical resistance in the concrete and that unreliable measurements can be sorted out when the curves do not follow the theoretical pattern.

  4. Electrochemical behavior of steel in concrete and evaluation of the corrosion rate

    Energy Technology Data Exchange (ETDEWEB)

    Videm, K. [Univ. of Oslo (Norway). Centre for Materials Science; Myrdal, R. [Rescon AS, Sagstua (Norway)

    1997-09-01

    Various electrochemical methods for evaluation of corrosion of steel reinforcement in concrete were studied regarding their applicability in the field. Laboratory experiments were carried out with steel in synthetic pore water and in concrete blocks with chloride (Cl{sup {minus}}) additions. Field measurements were performed at a large, coastal concrete bridge. Methods examined included manual potential mapping, automatic measurements of corrosion potential (E{sub corr}) with embedded reference electrodes (RE), potentiokinetic linear polarization resistance (LPR) measurements with cut reinforcement bars, analysis of the shape of galvanostatic charging curves, and LPR measurements of the reinforcement with a commercial instrument containing a guard ring. Corrosion rates determined with the guard electrode (GE) instrument were not in good agreement with estimates based upon potential mapping or visual inspection. Because of the high interfacial capacitance (C) of the steel in concrete, potentiokinetic LPR measurements will ill-suited for determination of corrosion rates. Goo experience was obtained by computer modeling of the galvanostatic charging curve with calculation of the polarization resistance (R{sub p}) from this type of data. Advantages of this method were that it was influenced little by electrical resistance in the concrete and that unreliable measurements could be sorted out when curves did not follow the theoretical pattern.

  5. Corrosion behaviour of laser surface melted magnesium alloy AZ91D

    International Nuclear Information System (INIS)

    Taltavull, C.; Torres, B.; Lopez, A.J.; Rodrigo, P.; Otero, E.; Atrens, A.; Rams, J.

    2014-01-01

    A high power diode laser (HPDL) was used to produce laser surface melting (LSM) treatments on the surface of the Mg alloy AZ91D. Different treatments with different microstructures were produced by varying the laser-beam power and laser-scanning speed. Corrosion evaluation, using hydrogen evolution and electrochemical measurements, led to a relationship between microstructure and corrosion. Most corrosion rates for LSM treated specimens were within the scatter of the as-received AZ91D, whereas some treatments gave higher corrosion rates and some of the samples had corrosion rates lower than the average of the corrosion rate for AZ91D. There were differences in corroded surface morphology. Nevertheless laser treatments introduced surface discontinuities, which masked the effect of the microstructure. Removing these surface defects decreased the corrosion rate for the laser-treated samples. - Highlights: • Corrosion behavior of AZ91D Mg alloys is intimately related with its microstructure. • Laser surface melting treatments allows surface modification of the microstructure. • Different laser parameters can achieve different microstructures. • Controlling laser parameters can produce different corrosion rates and morphologies. • Increase of surface roughness due to laser treatment is relevant to the corrosion rate

  6. Effect of electrochemical corrosion on the subsurface microstructure evolution of a CoCrMo alloy in albumin containing environment

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhongwei; Yan, Yu, E-mail: yanyu@ustb.edu.cn; Su, Yanjing; Qiao, Lijie

    2017-06-01

    Highlights: • Accelerated electrochemical corrosion results in severer plastic deformation with finer grains. • Lower applied potential can increase protein adsorption on sample surfaces. • The tribo-film decreases the shear stresses and relief subsurface deformation. • Tribocorrosion induced passive film can suppress the annihilation of stacking faults. - Abstract: The subsurface microstructures of metallic implants play a key role in bio-tribocorrosion. Due to wear or change of local environment, the implant surface can have inhomogeneous electrochemical corrosion properties. In this work, the effect of electrochemical corrosion conditions on the subsurface microstructure evolution of CoCrMo alloys for artificial joints was investigated. Transmission electron microscope (TEM) was employed to observe the subsurface microstructures of worn areas at different applied potentials in a simulated physiological solution. The results showed that applied potentials could affect the severity of the subsurface deformation not only by changing the surface passivation but also affecting the adsorption of protein on the alloy surface.

  7. Evaluation of structural behaviour and corrosion resistant of austenitic AISI 304 and duplex AISI 2304 stainless steel reinforcements embedded in ordinary Portland cement mortars

    International Nuclear Information System (INIS)

    Medina, E.; Cobo, A.; Bastidas, D. M.

    2012-01-01

    The mechanical and structural behaviour of two stainless steels reinforcements, with grades austenitic EN 1.4301 (AISI 304) and duplex EN 1.4362 (AISI 2304) have been studied, and compared with the conventional carbon steel B500SD rebar. The study was conducted at three levels: at rebar level, at section level and at structural element level. The different mechanical properties of stainless steel directly influence the behaviour at section level and structural element level. The study of the corrosion behaviour of the two stainless steels has been performed by electrochemical measurements, monitoring the corrosion potential and the lineal polarization resistance (LPR), of reinforcements embedded in ordinary Portland cement (OPC) mortar specimens contaminated with different amount of chloride over one year time exposure. Both stainless steels specimens embedded in OPC mortar remain in the passive state for all the chloride concentration range studied after one year exposure. (Author) 26 refs.

  8. Development of Advanced Electrochemical Emission Spectroscopy for Monitoring Corrosion in Simulated DOE Liquid Waste

    Energy Technology Data Exchange (ETDEWEB)

    Digby D. Macdonald; Brian M. Marx; Sejin Ahn; Julio de Ruiz; Balaji Soundararaja; Morgan Smith; and Wendy Coulson

    2008-01-15

    Various forms of general and localized corrosion represent principal threats to the integrity of DOE liquid waste storage tanks. These tanks, which are of a single wall or double wall design, depending upon their age, are fabricated from welded carbon steel and contain a complex waste-form comprised of NaOH and NaNO{sub 3}, along with trace amounts of phosphate, sulfate, carbonate, and chloride. Because waste leakage can have a profound environmental impact, considerable interest exists in predicting the accumulation of corrosion damage, so as to more effectively schedule maintenance and repair. The different tasks that are being carried out under the current program are as follows: (1) Theoretical and experimental assessment of general corrosion of iron/steel in borate buffer solutions by using electrochemical impedance spectroscopy (EIS), ellipsometry and XPS techniques; (2) Development of a damage function analysis (DFA) which would help in predicting the accumulation of damage due to pitting corrosion in an environment prototypical of DOE liquid waste systems; (3) Experimental measurement of crack growth rate, acoustic emission signals and coupling currents for fracture in carbon and low alloy steels as functions of mechanical (stress intensity), chemical (conductivity), electrochemical (corrosion potential, ECP), and microstructural (grain size, precipitate size, etc) variables in a systematic manner, with particular attention being focused on the structure of the noise in the current and its correlation with the acoustic emissions; (4) Development of fracture mechanisms for carbon and low alloy steels that are consistent with the crack growth rate, coupling current data and acoustic emissions; (5) Inserting advanced crack growth rate models for SCC into existing deterministic codes for predicting the evolution of corrosion damage in DOE liquid waste storage tanks; (6) Computer simulation of the anodic and cathodic activity on the surface of the steel samples

  9. Corrosion behaviour of Ni–Co alloy coatings at Kish Island (marine ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. In this study, the corrosion behaviour of Ni-Co alloys with low Co content, electroplated on steel substrate in sulphate bath, was investigated. The morphology of coatings was studied by optical and SEM microscopy. The corrosion products were analyzed using EDX. The results showed that Ni–1%Co coatings had ...

  10. Corrosion behaviour of Ni–Co alloy coatings at Kish Island

    Indian Academy of Sciences (India)

    In this study, the corrosion behaviour of Ni-Co alloys with low Co content, electroplated on steel substrate in sulphate bath, was investigated. The morphology of coatings was studied by optical and SEM microscopy. The corrosion products were analyzed using EDX. The results showed that Ni–1% Co coatings had a better ...

  11. Corrosion behaviour of Ni–Co alloy coatings at Kish Island (marine ...

    Indian Academy of Sciences (India)

    In this study, the corrosion behaviour of Ni-Co alloys with low Co content, electroplated on steel substrate in sulphate bath, was investigated. The morphology of coatings was studied by optical and SEM microscopy. The corrosion products were analyzed using EDX. The results showed that Ni–1% Co coatings had a better ...

  12. Improvements in the corrosion resistance and biocompatibility of biomedical Ti–6Al–7Nb alloy using an electrochemical anodization treatment

    International Nuclear Information System (INIS)

    Huang, Her-Hsiung; Wu, Chia-Ping; Sun, Ying-Sui; Lee, Tzu-Hsin

    2013-01-01

    The biocompatibility of an implant material is determined by its surface characteristics. This study investigated the application of an electrochemical anodization surface treatment to improve both the corrosion resistance and biocompatibility of Ti–6Al–7Nb alloy for implant applications. The electrochemical anodization treatment produced an Al-free oxide layer with nanoscale porosity on the Ti–6Al–7Nb alloy surface. The surface topography and microstructure of Ti–6Al–7Nb alloy were analyzed. The corrosion resistance was investigated using potentiodynamic polarization curve measurements in simulated blood plasma (SBP). The adhesion and proliferation of human bone marrow mesenchymal stem cells to test specimens were evaluated using various biological analysis techniques. The results showed that the presence of a nanoporous oxide layer on the anodized Ti–6Al–7Nb alloy increased the corrosion resistance (i.e., increased the corrosion potential and decreased both the corrosion rate and the passive current) in SBP compared with the untreated Ti–6Al–7Nb alloy. Changes in the nanotopography also improved the cell adhesion and proliferation on the anodized Ti–6Al–7Nb alloy. We conclude that a fast and simple electrochemical anodization surface treatment improves the corrosion resistance and biocompatibility of Ti–6Al–7Nb alloy for biomedical implant applications. - Highlights: ► Simple/fast electrochemical anodization was applied to biomedical Ti–6Al–7Nb surface. ► Anodized surface had nano-porous topography and contained Al-free oxide layer. ► Anodized surface raised corrosion resistance in three simulated biological solutions. ► Anodized surface enhanced cell adhesion and cell proliferation. ► Electrochemical anodization has potential as biomedical implant surface treatment

  13. [The effect of epigallocatechin gallate (EGCG) on the surface properties of nickel-chromium dental casting alloys after electrochemical corrosion].

    Science.gov (United States)

    Qiao, Guang-yan; Zhang, Li-xia; Wang, Jue; Shen, Qing-ping; Su, Jian-sheng

    2014-08-01

    To investigate the effect of epigallocatechin gallate (EGCG) on the surface properties of nickel-chromium dental alloys after electrochemical corrosion. The surface morphology and surface structure of nickel-chromium dental alloys were examined by stereomicroscope and scanning electron microscopy before and after electrochemical tests in 0 g/L and 1.0 g/L EGCG artificial saliva. The surface element component and chemical states of nickel-chromium dental alloys were analyzed by X-ray photoelectron spectrograph after electrochemical tests in 0 g/L and 1.0 g/L EGCG artificial saliva. More serious corrosion happened on the surface of nickel-chromium alloy in 1.0 g/L EGCG artificial saliva than in 0 g/L EGCG. The diameters of corrosion pits were smaller, and the dendrite structure of the alloy surface was not affected in 0 g/L EGCG. While the diameters of corrosion pits were larger, the dendritic interval of the alloy surface began to merge, and the dendrite structure was fuzzy in 1.0 g/L EGCG. In addition, the O, Ni, Cr, Be, C and Mo elements were detected on the surface of nickel-chromium alloys after sputtered for 120 s in 0 g/L EGCG and 1.0 g/L EGCG artificial saliva after electrochemical corrosion, and the surface oxides were mainly NiO and Cr(2)O(3). Compared with 0 g/L EGCG artificial saliva, the content of O, NiO and Cr(2)O(3) were lower in 1.0 g/L EGCG. The results of surface morphology and the corrosion products both show that the corrosion resistance of nickel-chromium alloys become worse and the oxide content of corrosion products on the surface reduce in 1.0 g/L EGCG artificial saliva.

  14. Investigation of selective corrosion resistance of aged lean duplex stainless steel 2101 by non-destructive electrochemical techniques

    International Nuclear Information System (INIS)

    Gao Juan; Jiang Yiming; Deng Bo; Zhang Wei; Zhong Cheng; Li Jin

    2009-01-01

    Lean duplex stainless steel 2101 (LDX2101) shows wide application potential due to its better corrosion performance and lower cost than traditional 304 austenite steel. This paper investigates the effects of thermal aging treatments at 700 deg. C for various aging times up to 100 h on the selective corrosion resistance of LDX2101 by two non-destructive electrochemical measurements: double-loop electrochemical potentiokinetic reactivation (DL-EPR) and electrochemical impedance spectroscopy (EIS). The evolution of microstructure was examined by optical microscopy, SEM microscopy and X-ray diffraction techniques (XRD). The results showed that the two applied electrochemical measurements agreed very well. Both methods were able to reveal the relationship between microstructure and selective corrosion resistance, which was related to the formation of chromium- and molybdenum-depleted zones around the precipitates, especially the σ phase, during aging. Nevertheless, more information could be obtained using EIS methods, including the interfacial charge transfer reaction and the corrosion product adsorption process. The results suggest that the susceptibility of the aged alloy to selective corrosion is presumably codetermined by the formation of chromium- and molybdenum-depleted areas, as well as by the replenishment of them, in these areas from the bulk during aging.

  15. [The effect of hydrogen peroxide on the electrochemical corrosion properties and metal ions release of nickel-chromium dental alloys].

    Science.gov (United States)

    Wang, Jue; Qiao, Guang-yan

    2013-04-01

    To investigate the effect of hydrogen peroxide on the electrochemical corrosion and metal ions release of nickel-chromium dental alloys. The corrosion resistance of nickel-chromium dental alloys was compared by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PD) methods in artificial saliva after immersed in different concentrations of hydrogen peroxide for 112 h. The metal ions released from nickel-chromium dental alloys to the artificial saliva were detected after electrochemical measurements using inductively coupled plasma mass spectrometry (ICP-MS). The data was statistically analyzed by analysis of variance (ANOVA) using SPSS 13.0 software package. The electrochemical experiment showed that the sequence of polarization resistance in equivalent circuit (Rct), corrosion potential (Ecorr), pitting breakdown potential (Eb), and the difference between Ecorr and Eb representing the "pseudo-passivation" (δE) of nickel-chromium alloys in artificial saliva was 30% alloys to the artificial saliva, and the order of the concentrations of metal ions was 0% corrosion resistance of nickel-chromium dental alloys decrease after immersed in different concentrations of hydrogen peroxide for 112 h. Nickel-chromium dental alloys are more prone to corrosion in the artificial saliva with the concentration of hydrogen peroxide increased, and more metal ions are released in the artificial saliva.

  16. Effect of electrochemical corrosion on the subsurface microstructure evolution of a CoCrMo alloy in albumin containing environment

    Science.gov (United States)

    Wang, Zhongwei; Yan, Yu; Su, Yanjing; Qiao, Lijie

    2017-06-01

    The subsurface microstructures of metallic implants play a key role in bio-tribocorrosion. Due to wear or change of local environment, the implant surface can have inhomogeneous electrochemical corrosion properties. In this work, the effect of electrochemical corrosion conditions on the subsurface microstructure evolution of CoCrMo alloys for artificial joints was investigated. Transmission electron microscope (TEM) was employed to observe the subsurface microstructures of worn areas at different applied potentials in a simulated physiological solution. The results showed that applied potentials could affect the severity of the subsurface deformation not only by changing the surface passivation but also affecting the adsorption of protein on the alloy surface.

  17. The detailed analysis of the spray time effects of the aluminium coating using self-generated atmospheric plasma spray system on the microstructure and corrosion behaviour

    Directory of Open Access Journals (Sweden)

    Sh. Khandanjou

    Full Text Available In the present paper our aim is to investigate the effect of the spray time of the aluminium coated layers on the microstructure and corrosion behaviour. For this purpose we use the self-generated atmospheric plasma spray system for coating of aluminium on the carbon steel substrate. The different thicknesses of coating are created. To evaluate this effect we use the several analyses such as X-ray diffraction, scanning electron microscope, Micro hardness analysis by Vickers method, Adhesion strength analysis and electrochemical polarization test. The results are very interesting and show that due to low porosity, thicker layers are more homogeneous. The nanoparticles are observed in the thicker layers. The micro hardness tests show that the thicker layers have the better micro hardness value. Next, the adhesion strength tests illustrate that the highest adhesion strength are for longer spray times. On the other hand, the corrosion resistance behaviour of the coating is investigated by electrochemical polarization test. It is shown that the corrosion resistance increases by increasing the thickness due to low percentage of porosity. Keywords: Plasma spray, Thickness, Aluminium, Micro hardness, Corrosion resistance

  18. Relation between the semiconducting properties of passive films and electrochemical and corrosion properties

    Science.gov (United States)

    Harrington, Scott Peter

    Aqueous corrosion is a common materials degradation mechanism and is thought to be a likely failure mode of high level nuclear waste canisters. Corrosion damage is often mitigated by a protective oxide film that forms naturally on many metals. The semiconducting properties of these films often have a large impact on the electrochemical and corrosion behavior of metal-passive film systems. In this study the flatband potential and charge carrier density of the films that form on Alloy C22, Cr, Ti, Fe, Ni, Mo and mild steel were evaluated by Mott-Schottky analysis. All films with the exception of Ni oxide were n-type at all measured frequencies. The calculation of the flatband potentials and charge carrier densities was complicated by measured capacitances that were frequency dependent. A new method was proposed to fit the frequency dispersion with a Constant Phase Element (CPE) and then expressions developed by Brug et al. [J. Electroanal. Chem., 176, 275 (1984)] or Hsu and Mansfeld [Corrosion, 57, 747 (2001)] were used calculate effective capacitances as a function of potential. The success of this method was evaluated using cathodic polarization tests. Flatband potentials calculated using Brug et al.'s expression were in excellent agreement with the onset potential of reduction current growth in polarization scans. It was found that films with more negative flatband potentials were less susceptible to localized attack due to the slower reduction kinetics associated with low flatband potentials. Alloy C22 has a very negative flatband potential and is highly resistant to localized corrosion at room temperature but improved reduction kinetics at elevated temperature contributes to Alloy C22's susceptibility to metastable pitting at high temperatures.

  19. The Corrosion Behaviour of WC-Co-Ru Alloys in Aggressive Chloride Media

    Directory of Open Access Journals (Sweden)

    J. H. Potgieter

    2014-01-01

    Full Text Available Hardmetals possess excellent wear resistance, making them suitable alloys in several industrial applications. Mine waters with both dissolved chloride and sulphate salts can be severely corrosive and can limit the application of hardmetal tools in the mining industry. Ru additions to these alloys can refine and improve selected mechanical properties, but its influence on the corrosion resistance is unknown. A series of WC-Co-Ru alloys was evaluated in different chloride containing media to investigate their corrosion resistance. Standard electrochemical corrosion tests, chronoamperometric measurements, and surface analyses with Raman spectroscopy were conducted. An increasing amount of Ru improves the corrosion resistance of all the alloys. The effect is not as dramatic as that observed with stainless steels containing Ru in corrosive media. In both corrosive media Ru decreased the cathodic Tafel constant and has a retarding influence on the cathodic part of the corrosion reaction. Raman analyses indicated the presence of tungsten oxide, hydrated tungsten oxide compounds, and CoO and Co3O4 formed on the alloy surfaces during the corrosion process.

  20. The electrochemical behaviour of various non-precious Ni and Co based alloys in artificial saliva

    Directory of Open Access Journals (Sweden)

    Mareci D.

    2005-07-01

    Full Text Available Five non-precious Ni-Co based alloys were analyzed with respect to their corrosion behaviour. The correlation between the amount of the elements Cr, Mo, V and the corrosion behaviour, expressed by the PREN (pitting resistance equivalent number index in the case of the allied steels, was extended for Ni-Cr and Co-Cr dental alloys characterization. Open circuit potential, corrosion current densities, as a measure of the corrosion rate, and main parameters of the corrosion process were evaluated from linear and cyclic polarization curves, for five Ni-Cr or Co-Cr alloys in an Afnor type artificial saliva. The maintenance times of the alloy in the corrosive medium influence the corrosion rate; the corrosion current values decrease with the maintenance time due to their passivation in solution. The microscopic analysis of the alloy surfaces shows that this passivation in solution does not modify the corrosion type. The alloys with PREN 32.9 are susceptible of localized corrosion.

  1. Corrosion behaviour of amorphous Ti48Cu52, Ti50Cu50 and ...

    Indian Academy of Sciences (India)

    Unknown

    wire using silver paint so as to maintain good electrical contact during corrosion testing. The region of the sam- ple which was painted with silver paint was covered with epoxy resin in order to prevent any reaction of the silver paint with the solution during the electrochemical studies. Potentiodynamic polarization studies ...

  2. Study of corrosion behaviour in saturated bentonite barrier Corroben

    International Nuclear Information System (INIS)

    Azkarate, I.; Insausti, M.; Medina, V.

    2004-01-01

    The corrosion behavior in saturated bentonite of various candidate metallic materials, to be used in the fabrication of containers of high level radioactive waste granite repositories, has been studied in this project. Due to the multi-barrier concept in which the canisters are surrounded by a clay barrier of compacted bentonite blocks, special attention has been paid to the characterization of corrosion products and the interaction between these and the repository sealing bentonite. The following metallic materials have been studied: S355 carbon steel, AISI 316L stainless steel, Cu-ETP electrolytic copper and Cu30Ni alloy. Samples of the alloys have been embedded in saturated bentonite to a water content of 25%, and compacted. The obtained pastilles have been introduced in autoclaves and tested at different temperatures and times ranging from one to 18 months. Once tests have concluded, several parameters have been evaluated: corrosion morphology, general corrosion rates calculated by gravimetric methods, nature and composition of the corrosion products and penetration of the corrosion products into the bentonite. Experimental data obtained are used to developed models of the corrosion behavior of canisters under disposal conditions. Results show that S355 carbon steel has suffered the highest general corrosion attack, with average corrosion rates of 10 per year and maximum penetration of 100 measured in specimens tested at 75C during 18 months. The most common analyzed corrosion product has been siderite, FeCO3. Formation of siderite, in the test conditions, effectively passivated the steel because of its stable and adherent feature. In test carried out at 25 and 5 C, sulfur rich corrosion products are observed, thus indicating a microbiologically corrosion phenomena due to the metabolic activity of bacteria present in the bentonite. No appreciable general corrosion rates, nor sensitivity to localized corrosion, has been observed in the AISI 316L stainless steel

  3. Effects of acidity and alkalinity on corrosion behaviour of Al-Zn-Mg based anode alloy

    Science.gov (United States)

    Ma, Jingling; Wen, Jiuba; Li, Quanan; Zhang, Qin

    2013-03-01

    Effects of 1 M HCl, 0.6 M NaCl with different pH values and 4 M NaOH solutions on the corrosion behaviour of Al-5Zn-1Mg-0.02In-0.05Ti-0.5Mn (wt%) alloy have been investigated using measurements of self-corrosion, potentiodynamic polarization, cyclic polarization experiment combined with open circuit potential technique and scanning electron microscopy. The corrosion behaviour of the alloy was found to be dependant on the Cl-, OH- ions and pH value. In acidic or slightly neutral solutions, general and pitting corrosion occurred simultaneously. In contrast, exposure to alkaline solutions results in general corrosion which was traced back to the dissolution of the resistive oxidation film on the surface of the alloy. Experience revealed that the alloy was susceptible to pitting corrosion in all chloride solution. The alloy undergoes two types of localized corrosion process, leading to the formation of hemispherical and crystallographic pits. Polarization resistance measurements which are in good agreement with those of self-corrosion, show that the corrosion kinetic is minimized in slightly neutral solutions (pH = 7).

  4. Influence of Ti, C and N concentration on the intergranular corrosion behaviour of AISI 316Ti and 321 stainless steels

    International Nuclear Information System (INIS)

    Pardo, A.; Merino, M.C.; Coy, A.E.; Viejo, F.; Carboneras, M.; Arrabal, R.

    2007-01-01

    Intergranular corrosion behaviour of 316Ti and 321 austenitic stainless steels has been evaluated in relation to the influence exerted by modification of Ti, C and N concentrations. For this evaluation, electrochemical measurements - double loop electrochemical potentiokinetic reactivation (DL-EPR) - were performed to produce time-temperature-sensitization (TTS) diagrams for tested materials. Transmission (TEM) and scanning electron microscopy (SEM) were used to determine the composition and nature of precipitates. The addition of Ti promotes better intergranular corrosion resistance in stainless steels. The precipitation of titanium carbides reduces the formation of chromium-rich carbides, which occurs at lower concentrations. Also, the reduction of carbon content to below 0.03 wt.% improves sensitization resistance more than does Ti content. The presence of Mo in AISI 316Ti stainless steel reduces chromium-rich carbide precipitation; the reason is that Mo increases the stability of titanium carbides and tends to replace chromium in the formation of carbides and intermetallic compounds, thus reducing the risks of chromium-depletion

  5. Electrochemical Behavior of Bilayer Thermal-Spray Coatings in Low-Temperature Corrosion Protection

    Directory of Open Access Journals (Sweden)

    Esmaeil Sadeghimeresht

    2017-09-01

    Full Text Available Cr3C2-NiCr coatings are greatly used to protect critical components in corrosive environments and to extend their lifetime and/or improve functional performance. However, the pores formed during spraying restrict the coating’s applicability area for many corrosion protection applications. To overcome this technical challenge, bilayer coatings have been developed, in which an additional layer (the so-called “intermediate layer” is deposited on the substrate before spraying the Cr3C2-NiCr coating (the so-called “top layer”. The corrosion behavior of the bilayer coating depends on the composition and microstructure of each layer. In the present work, different single-layer coatings (i.e., Cr3C2-NiCr, Fe- and Ni-based coatings were initially sprayed by a high-velocity air fuel (HVAF process. Microstructure analysis, as well as electrochemical tests, for example, open-circuit potential (OCP and polarization tests, were performed. The potential difference (ΔE had a great influence on galvanic corrosion between the top and intermediate layers, and thus, the coatings were ranked based on the OCP values (from high to low as follows: NiCoCrAlY > NiCr > Cr3C2-NiCr > NiAl > Fe-based coatings (alloyed with Cr > pure Ni. The Ni-based coatings were chosen to be further used as intermediate layers with the Cr3C2-NiCr top layer due to their capabilities to show high OCP. The corrosion resistance (Rp of the bilayer coatings was ranked (from high to low as follows: NiCoCrAlY/Cr3C2-NiCr > NiCr/Cr3C2-NiCr > NiAl/Cr3C2-NiCr > Ni/Cr3C2-NiCr. It was shown that splat boundaries and interconnected pores are detrimental for corrosion resistance, however, a sufficient reservoir of protective scale-forming elements (such as Cr or/and Al in the intermediate layer can significantly improve the corrosion resistance.

  6. Corrosion behaviour of construction materials for high temperature steam electrolysers

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey; Petrushina, Irina; Christensen, Erik

    2011-01-01

    Different types of commercially available stainless steels, Ni-based alloys as well as titanium and tantalum were evaluated as possible metallic bipolar plates and construction materials. The corrosion resistance was measured under simulated conditions corresponding to the conditions in high...... to corrosion under strong anodic polarisation. Among alloys, Ni-based showed the highest corrosion resistance in the simulated PEM electrolyser medium. In particular, Inconel 625 was the most promising among the tested corrosion-resistant alloys for the anodic compartment in high temperature steam electrolysis....... Tantalum showed outstanding resistance to corrosion in selected media. On the contrary, passivation of titanium was weak, and the highest rate of corrosion among all tested materials was observed for titanium at 120 degrees C....

  7. Electrochemical Impedance Spectroscopy Study on Corrosion Protection of Acrylate Nanocomposite on Mild Steel Doped Carbon Nanotubes

    International Nuclear Information System (INIS)

    Mahmud, M R; Akhir, M M; Shamsudin, M S; Afaah, A N; Aadila, A; Asib, N A M; Harun, M K; Abdullah, S; Alrokayan, Salman A H; Khan, Haseeb A; Rusop, M

    2015-01-01

    Acrylate:carbon nanotubes (A:CNTs) nanocomposite thin film was prepared by sol- gel technique. The corrosion coating protection of acrylate:carbon nanotubes (CNTs) nanocomposite thin film has been coated on mild steel characterised by electrochemical impedance spectrometer (EIS) measurement and equivalent circuit model are employed to analyse coating impedance for corrosion protection. In this study, 3.5 w/v % sodium chloride (NaCl) solution was immersed the acrylate:carbon nanotubes nanocomposite thin film. As the results, the surface morphology were found that there formation of carbon nanotubes with good distribution on acrylate-based coating. From EIS measurement, A:CNTs nanocomposite thin film with 0.4 w/v % contain of CNTs was exhibited the highest coating impedance from Nyquist graph after immersed in sodium chloride solution and may provide the excellent corrosion protection. The Bode plots have shown the impedance is high at the beginning from the time at high frequency and slightly decreases with value of frequency become smaller. (paper)

  8. Use of Electrochemical Noise to Assess Corrosion in Kraft Continuous Digesters

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, S.J.

    2004-11-29

    Electrochemical noise (EN) probes were deployed in two continuous kraft digesters at a variety of locations representative of corrosion throughout the vessels. Current and potential noise, the temperature at each probe location, and the value of up to 60 process parameters (flow rates, liquor chemistry, etc.) were monitored continuously during each experiment. The results indicate that changes in furnish composition and process upsets were invariably associated with concurrent substantial changes in EN activity throughout the vessels. Post-test evaluation of the mild steel electrode materials in both vessels confirmed general corrosion of a magnitude consistent with historical trends in the respective vessels as well as values qualitatively (and semi-quantitatively) related to EN current sums for each electrode pair. Stainless steel electrodes representing 309LSi and 312 overlay repairs exhibited zero wastage corrosion--as did the actual overlays--but the EN data indicated periodic redox activity on the stainless steel that varied with time and position within the vessel. Little or no correlation between EN probe activity and other operational variables was observed in either vessel. Additional details for each digester experiment are summarized.

  9. In-situ electrochemical study of interaction of tribology and corrosion in artificial hip prosthesis simulators.

    Science.gov (United States)

    Yan, Yu; Dowson, Duncan; Neville, Anne

    2013-02-01

    The second generation Metal-on-Metal (MoM) hip replacements have been considered as an alternative to commonly used Polyethylene-on-Metal (PoM) joint prostheses due to polyethylene wear debris induced osteolysis. However, the role of corrosion and the biofilm formed under tribological contact are still not fully understood. Enhanced metal ion concentrations have been reported widely from hair, blood and urine samples of patients who received metal hip replacements and in isolated cases when abnormally high levels have caused adverse local tissue reactions. An understanding of the origin of metal ions is really important in order to design alloys for reduced ion release. Reciprocating pin-on-plate wear tester is a standard instrument to assess the interaction of corrosion and wear. However, more realistic hip simulator can provide a better understanding of tribocorrosion process for hip implants. It is very important to instrument the conventional hip simulator to enable electrochemical measurements. In this study, simple reciprocating pin-on-plate wear tests and hip simulator tests were compared. It was found that metal ions originated from two sources: (a) a depassivation of the contacting surfaces due to tribology (rubbing) and (b) corrosion of nano-sized wear particles generated from the contacting surfaces. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Detection of localized and general corrosion of mild steel in simulated defense nuclear waste solutions using electrochemical noise analysis

    International Nuclear Information System (INIS)

    Edgemon, G.L.; Ohl, P.C.; Bell, G.E.C.; Wilson, D.F.

    1995-12-01

    Underground waste tanks fabricated from mild steel store more than 60 million gallons of radioactive waste from 50 years of weapons production. Leaks are suspected in a significant number of tanks. The probable modes of corrosion failures are reported to be localized corrosion (e.g. nitrate stress corrosion cracking and pitting). The use of electrochemical noise (EN) for the monitoring and detection of localized corrosion processes has received considerable attention and application over the last several years. Proof of principle laboratory tests were conducted to verify the capability of EN evaluation to detect localized corrosion and to compare the predictions of general corrosion obtained from EN with those derived from other sources. Simple, pre-fabricated flat and U-bend specimens of steel alloys A516-Grade 60 (UNS K02100) and A537-CL 1 (UNS K02400) were immersed in temperature controlled simulated waste solutions. The simulated waste solution was either 5M NaNO 3 with 0.3M NaOH at 90 C or 11M NaNO 3 with 0.15M NaOH at 95 C. The electrochemical noise activity from the specimens was monitored and recorded for periods ranging between 140 and 240 hours. At the end of each test period, the specimens were metallographically examined to correlated EN data with corrosion damage

  11. Electrochemical studies on Li/K ion exchange behaviour in K 4 Fe ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 127; Issue 1. Electrochemical studies on Li+/K+ ion exchange behaviour in ... Abstract. The electrochemical studies of anhydrous K4Fe(CN)6 is reported. Anhydrous material was produced after dehydrating K4Fe(CN)6.3H2O crystal at 200°C in an open atmosphere.

  12. Electrochemical behaviour of silver in borate buffer solutions

    International Nuclear Information System (INIS)

    Zaky, Ayman M.; Assaf, Fawzi H.; Abd El Rehim, Sayed S.; Mohamed, Basheer

    2004-01-01

    The electrochemical behaviour of Ag in aqueous 0.15 M borax and 0.15 M boric acid buffer solution was studied under various conditions using cyclic voltammetry and potentiostatic techniques. It was found that the anodic polarization curve of Ag in borate buffer solution was characterized by the appearance of two potential regions, active and passive, prior to the oxygen evolution reaction. The active potential region was characterized by the appearance of three anodic peaks, the first two peaks A 1 and A 2 correspond to the oxidation of Ag and formation of [Ag(OH) 2 ] - soluble compound and a passive film of Ag 2 O on the electrode surface. The third anodic peak corresponds to the conversion of both [Ag(OH) 2 ] - and Ag 2 O to Ag 2 O 2 . X-ray diffraction patterns confirmed the existence of Ag 2 O and Ag 2 O 2 passive layers on the electrode surface potentiodynamically polarized up to 800 mV. Potentiostatic current transient measurements showed that the formation of Ag 2 O and Ag 2 O 2 involves a nucleation and growth mechanism under diffusion control

  13. Electrochemical behaviour of uranium (IV) in DMF at vitreous carbon

    International Nuclear Information System (INIS)

    Afonso, M.L.; Gomes, A.; Carvalho, A.; Alves, L.C.; Wastin, F.; Goncalves, A.P.

    2009-01-01

    The electrochemical behaviour of UCl 4 (0.01 mol L -1 up to 0.05 mol L -1 ) in 0.1 mol L -1 TBAPF 6 /DMF solution at vitreous carbon was studied, at room temperature, by cyclic voltammetry and potentiostatic techniques. The electrolytic solutions were analyzed by UV spectroscopy (UV), and the electrodeposited films were characterized by Rutherford Backscattering Spectroscopy (RBS) and X-ray diffraction (XRD). The cyclic voltammetric results, at low UCl 4 concentrations (0.01 mol L -1 ), point that the reduction of U(IV) to U(0) occurs in two steps involving mainly U(IV) and U(III) species. The first electron transfer reaction is quasi-reversible and the second irreversible. The diffusion coefficient of U(IV) in DMF and the charge rate constant were determined to be 4.78 x 10 -7 cm 2 s -1 and 1.93 x 10 -3 cm s -1 (at 0.02 V s -1 ), respectively. RBS data obtained from samples prepared at constant potential (-3.10 V) during 3 h at room temperature, indicated the presence of uranium particles deposited all over the vitreous carbon surface with aggregates in some places, confirming that the second reduction step corresponds to uranium electrodeposition. No crystallographic ordering could be seen by XRD, pointing to an amorphous character of the uranium films.

  14. Effect of surface morphology on atmospheric corrosion behaviour of ...

    Indian Academy of Sciences (India)

    Wintec

    adverse effect of quenched-in defects on the corrosion resistance of Fe34Ni36Cr10P14B6 amorphous alloy has been reported by some investigators (Gravano et al 1992). The inferior corrosion resistance of the wheel side surface has been attributed to higher concentration of quenched- in defects due to higher cooling rate ...

  15. Corrosion behaviour of mooring chain steel in seawater

    NARCIS (Netherlands)

    Zhang, X.; Noel, N.; Ferrari, G.; Hoogland, M.G.

    2016-01-01

    Failures of mooring lines on floating production, storage and offloading systems (FPSOs) raise concern to the offshore industry. Localized corrosion of mooring chain is regarded as one of main failure mechanisms. The project of Localized Mooring Chain Corrosion (LMCC) is aiming at studying the

  16. Effects of climate and corrosion on concrete behaviour

    Science.gov (United States)

    Ismail, Mohammad; Egba, Ernest Ituma

    2017-11-01

    Corrosion of steel is a damaging agent that reduces the functional and structural responsibilities of reinforced concrete structures. Accordingly, reinforced concrete members in the environments that are prone to concrete carbonation or chloride attack coupled with high temperature and relative humidity suffer from accelerated corrosion of reinforcing material. Also, literature proves that climate influences corrosion of concrete, and suggests investigation of impact of corrosion on concrete based on climate zone. Therefore, this paper presents the effects of climate and corrosion on concrete behavior, using bond strength of concrete as a case study. Concrete specimens were prepared form concrete mix that was infested with 3.5 kgm-3 of sodium chloride to accelerate corrosion. The specimens were cured sodium chloride solution 3.5% by weight of water for 28 days before placing them in the exposure conditions. Pull-out tests were conducted at time intervals for one year to measure the impact of exposure condition and corrosion on bond strength of concrete. The results show reduction of bond strength of concrete by 32%, 28% and 8% after one year of subjection of the specimens to the unsheltered natural climate, sheltered natural climate, and laboratory ambient environment respectively. The findings indicate that the climate influences corrosion, which reduces the interlocking bond between the reinforcing bar and the adjacent concrete.

  17. Electrochemical evaluation of antibacterial drugs as environment-friendly inhibitors for corrosion of carbon steel in HCl solution

    International Nuclear Information System (INIS)

    Golestani, Gh.; Shahidi, M.; Ghazanfari, D.

    2014-01-01

    The effect of penicillin G, ampicillin and amoxicillin drugs on the corrosion behavior of carbon steel (ASTM 1015) in 1.0 mol L −1 hydrochloric acid solution was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) techniques. The inhibition efficiency was found to increase with increasing inhibitor concentration. The effect of temperature on the rate of corrosion in the absence and presence of these drugs was also studied. Some thermodynamic parameters were computed from the effect of temperature on corrosion and inhibition processes. Adsorption of these inhibitors was found to obey Langmuir adsorption isotherm. There was a case of mixed mode of adsorption here but while penicillin was adsorbed mainly through chemisorption, two other drugs were adsorbed mainly through physisorption. Potentiodynamic polarization measurements indicated that the inhibitors were of mixed type. In addition, this paper suggests that the electrochemical noise (EN) technique under open circuit conditions as the truly noninvasive electrochemical method can be employed for the quantitative evaluation of corrosion inhibition. This was done by using the standard deviation of partial signal (SDPS) for calculation of the amount of noise charges at the particular interval of frequency, thereby obtaining the inhibition efficiency (IE) of an inhibitor. These IE values showed a reasonable agreement with those obtained from potentiodynamic polarization and EIS measurements.

  18. Electrochemical evaluation of antibacterial drugs as environment-friendly inhibitors for corrosion of carbon steel in HCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Golestani, Gh.; Shahidi, M., E-mail: shahidi1965@gmail.com; Ghazanfari, D.

    2014-07-01

    The effect of penicillin G, ampicillin and amoxicillin drugs on the corrosion behavior of carbon steel (ASTM 1015) in 1.0 mol L⁻¹ hydrochloric acid solution was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) techniques. The inhibition efficiency was found to increase with increasing inhibitor concentration. The effect of temperature on the rate of corrosion in the absence and presence of these drugs was also studied. Some thermodynamic parameters were computed from the effect of temperature on corrosion and inhibition processes. Adsorption of these inhibitors was found to obey Langmuir adsorption isotherm. There was a case of mixed mode of adsorption here but while penicillin was adsorbed mainly through chemisorption, two other drugs were adsorbed mainly through physisorption. Potentiodynamic polarization measurements indicated that the inhibitors were of mixed type. In addition, this paper suggests that the electrochemical noise (EN) technique under open circuit conditions as the truly noninvasive electrochemical method can be employed for the quantitative evaluation of corrosion inhibition. This was done by using the standard deviation of partial signal (SDPS) for calculation of the amount of noise charges at the particular interval of frequency, thereby obtaining the inhibition efficiency (IE) of an inhibitor. These IE values showed a reasonable agreement with those obtained from potentiodynamic polarization and EIS measurements.

  19. Electrochemical behaviour of carbon paste electrodes enriched with tin oxide nanoparticles using voltammetry and electrochemical impedance spectroscopy.

    Science.gov (United States)

    Muti, Mihrican; Erdem, Arzum; Caliskan, Ayfer; Sınag, Ali; Yumak, Tugrul

    2011-08-01

    The effect of the SnO(2) nanoparticles (SNPs) on the behaviour of voltammetric carbon paste electrodes were studied for possible use of this material in biosensor development. The electrochemical behaviour of SNP modified carbon paste electrodes (CPE) was first investigated by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The performance of the SNP modified electrodes were compared to those of unmodified ones and the parameters affecting the response of the modified electrode were optimized. The SNP modified electrodes were then tested for the electrochemical sensing of DNA purine base adenine to explore their further development in biosensor applications. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Corrosion behaviour of metallic containers during long term interim storages

    International Nuclear Information System (INIS)

    Desgranges, C.; Feron, D.; Mazaudier, F.; Terlain, A.

    2001-01-01

    Two main corrosion phenomena are encountered in long term interim storage conditions: dry oxidation by the air when the temperature of high level nuclear wastes containers is high enough (roughly higher than 100 C) and corrosion phenomena as those encountered in outdoor atmospheric corrosion when the temperature of the container wall is low enough and so condensation is possible on the container walls. Results obtained with dry oxidation in air lead to predict small damages (less than 1μm on steels over 100 years at 100 C) and no drastic changes with pollutants. For atmospheric corrosion, first developments deal with a pragmatic method that gives assessments of the indoor atmospheric corrosivities. (author)

  1. Electrochemical Study of Polymer and Ceramic-Based Nanocomposite Coatings for Corrosion Protection of Cast Iron Pipeline

    Directory of Open Access Journals (Sweden)

    Ameen Uddin Ammar

    2018-02-01

    Full Text Available Coating is one of the most effective measures to protect metallic materials from corrosion. Various types of coatings such as metallic, ceramic and polymer coatings have been investigated in a quest to find durable coatings to resist electrochemical decay of metals in industrial applications. Many polymeric composite coatings have proved to be resistant against aggressive environments. Two major applications of ferrous materials are in marine environments and in the oil and gas industry. Knowing the corroding behavior of ferrous-based materials during exposure to these aggressive applications, an effort has been made to protect the material by using polymeric and ceramic-based coatings reinforced with nano materials. Uncoated and coated cast iron pipeline material was investigated during corrosion resistance by employing EIS (electrochemical impedance spectroscopy and electrochemical DC corrosion testing using the “three electrode system”. Cast iron pipeline samples were coated with Polyvinyl Alcohol/Polyaniline/FLG (Few Layers Graphene and TiO2/GO (graphene oxide nanocomposite by dip-coating. The EIS data indicated better capacitance and higher impedance values for coated samples compared with the bare metal, depicting enhanced corrosion resistance against seawater and “produce water” of a crude oil sample from a local oil rig; Tafel scans confirmed a significant decrease in corrosion rate of coated samples.

  2. Electrochemical Study of Polymer and Ceramic-Based Nanocomposite Coatings for Corrosion Protection of Cast Iron Pipeline

    Science.gov (United States)

    Ammar, Ameen Uddin; Shahid, Muhammad; Ahmed, Muhammad Khitab; Khan, Munawar; Khalid, Amir

    2018-01-01

    Coating is one of the most effective measures to protect metallic materials from corrosion. Various types of coatings such as metallic, ceramic and polymer coatings have been investigated in a quest to find durable coatings to resist electrochemical decay of metals in industrial applications. Many polymeric composite coatings have proved to be resistant against aggressive environments. Two major applications of ferrous materials are in marine environments and in the oil and gas industry. Knowing the corroding behavior of ferrous-based materials during exposure to these aggressive applications, an effort has been made to protect the material by using polymeric and ceramic-based coatings reinforced with nano materials. Uncoated and coated cast iron pipeline material was investigated during corrosion resistance by employing EIS (electrochemical impedance spectroscopy) and electrochemical DC corrosion testing using the “three electrode system”. Cast iron pipeline samples were coated with Polyvinyl Alcohol/Polyaniline/FLG (Few Layers Graphene) and TiO2/GO (graphene oxide) nanocomposite by dip-coating. The EIS data indicated better capacitance and higher impedance values for coated samples compared with the bare metal, depicting enhanced corrosion resistance against seawater and “produce water” of a crude oil sample from a local oil rig; Tafel scans confirmed a significant decrease in corrosion rate of coated samples. PMID:29495339

  3. Electrochemical Study of Polymer and Ceramic-Based Nanocomposite Coatings for Corrosion Protection of Cast Iron Pipeline.

    Science.gov (United States)

    Ammar, Ameen Uddin; Shahid, Muhammad; Ahmed, Muhammad Khitab; Khan, Munawar; Khalid, Amir; Khan, Zulfiqar Ahmad

    2018-02-25

    Coating is one of the most effective measures to protect metallic materials from corrosion. Various types of coatings such as metallic, ceramic and polymer coatings have been investigated in a quest to find durable coatings to resist electrochemical decay of metals in industrial applications. Many polymeric composite coatings have proved to be resistant against aggressive environments. Two major applications of ferrous materials are in marine environments and in the oil and gas industry. Knowing the corroding behavior of ferrous-based materials during exposure to these aggressive applications, an effort has been made to protect the material by using polymeric and ceramic-based coatings reinforced with nano materials. Uncoated and coated cast iron pipeline material was investigated during corrosion resistance by employing EIS (electrochemical impedance spectroscopy) and electrochemical DC corrosion testing using the "three electrode system". Cast iron pipeline samples were coated with Polyvinyl Alcohol/Polyaniline/FLG (Few Layers Graphene) and TiO₂/GO (graphene oxide) nanocomposite by dip-coating. The EIS data indicated better capacitance and higher impedance values for coated samples compared with the bare metal, depicting enhanced corrosion resistance against seawater and "produce water" of a crude oil sample from a local oil rig; Tafel scans confirmed a significant decrease in corrosion rate of coated samples.

  4. Study of corrosive-erosive wear behaviour of Al6061/albite composites

    International Nuclear Information System (INIS)

    Sharma, S.C.; Krishna, M.; Murthy, H.N. Narasimha; Tarachandra, R.; Satyamoorthy, M.; Bhattacharyya, D.

    2006-01-01

    This investigation analyses the influence of dispersed alumina particles on the wear behaviour of the Al/albite composites in a corrosive environment. The composites were prepared by modified pressure die-casting technique. The corrosive-erosive wear experiments were carried out on a proprietary corrosion-erosion wear tester to study the wear characteristics of the composites. The slurry was made up of water and alumina (size: 90-150 μm, proportion: 0-30 wt.%), while H 2 SO 4 (0.01, 0.1 and 1N) was added to create the corrosive conditions. Experiments were arranged to test the relationships among the corrosive-erosive wear rate, concentrations of H 2 SO 4 and alumina in the slurry, weight percent of albite in the composite, erosion speed and distance. Wear rate varies marginally at low speeds but sharply increases at higher speeds. The corrosive wear rate logarithmically increased with the increasing concentration of the corrosive medium. The effect of abrasive particles and corrosion medium on the wear behaviour of the composite is explained experimentally, theoretically and using scanning electron microscopy

  5. Non-destructive electrochemical techniques applied to the corrosion evaluation of the liner structures in nuclear power plants

    International Nuclear Information System (INIS)

    Martinez, I.; Castillo, A.; Andrade, C.

    2008-01-01

    The liner structure in nuclear power plants provides containment for the operation and therefore the study of its durability and integrity during its service life is an important issue. There are several causes for the deterioration of the liner, which in general involve corrosion due to its metallic nature. The present paper is aimed at describing the assessment of corrosion problems of two liners from two different nuclear power plants, which were evaluated using non-destructive electrochemical techniques. In spite of the testing difficulties arisen, from the results extracted it can be concluded that the electrochemical techniques applied are adequate for the corrosion evaluation. They provide important information about the integrity of the structure and allow for its evolution with time to be assessed

  6. Influence of alloying elements and density on aqueous corrosion behaviour of some sintered low alloy steels

    International Nuclear Information System (INIS)

    Kandavel, T.K.; Chandramouli, R.; Karthikeyan, P.

    2012-01-01

    Highlights: ► Corrosion of low alloy P/M steels under HCl acid pickling environment has been studied. ► Influence of density, strain and alloying elements on the rate of corrosion of the steels has been investigated. ► Residual porosity has significant effect on acid corrosion. ► Addition of the alloying elements Cu, Mo and Ti reduces the corrosion rate significantly. ► Carbide forming elements Mo and Ti improve further the resistance of the steels to aqueous corrosion. -- Abstract: Low alloy steels produced through powder metallurgy route of sintering followed by forging are promising candidate materials for high strength small components. Porosity in such steels poses a real challenge during acid pickling treatment, which is one of the processing steps during manufacturing. The present research work attempts to investigate the mechanism underlying the acid corrosion behaviour of some sintered low alloy steels under induced acid pickling conditions. Sintered-forged low alloy steel samples containing molybdenum (Mo), copper (Cu) and titanium (Ti) were subjected to aqueous corrosion attack by immersing the samples in 18% HCl (Hydrochloric acid) solution for 25 h. Sample weight loss and Fe (Iron) loss were estimated for the corroded samples. The morphology of the corroded surfaces was studied through metallography and scanning electron microscopy. Higher porosity alloys underwent enhanced corrosion rates. Both corrosion rate and iron loss are found to decrease linearly with reduction in porosity in all cases of the alloys. The alloying elements Mo, Ti and Cu, when added in combination, have played a complementary role in the reduction of corrosion rate by almost one order of magnitude compared to unalloyed steel. Presence of carbides of the carbide forming elements Mo and Ti played a positive role on the corrosion behaviour of the low alloy steels.

  7. Electrochemical synthesis and characterisation of hybrid materials polypyrrole/dodecatungstophosphate as protective agents against steel corrosion

    Science.gov (United States)

    Bonastre Cano, Jose Antonio

    hand, this pretreatment should guarantee appropriate conditions in order to obtain a coating with high adhesion on carbon steel. Once studied the better parameters for the synthesis of the hybrid material by cyclic voltammetry, hybrid material is morphological, chemical and electrochemical characterised by the following techniques: Cyclic Voltammetry, Scanning Electron Microscopy, Energy Dispersive X Ray, X Ray Photoelectron Spectroscopy and Electrochemical Impedance Spectroscopy. The hybrid material polypyrrole/PW 12O403-. chemical structure presents Fe oxides and hydroxide within the polypyrrole polycationic matrix. Hybrid material polypyrrol/PW12O403- diminishes the corrosion of carbon steel in NaOH and Porland cement filtering solutions. These cement solutions simulate the pore fluid conditions existing in cured mortar or concrete elements. Fe ion concentration data were determinated in corrosion tests. Voltammetric response of polymeric coatings was evaluated by cyclic voltammetry. Finally, the protection provided by hybrid material polypyrrole/PW 12O403, in oxidised and reduced state, was evaluated on carbon steel electrodes embedded in Portland cement mortars immersed in seawater and submitted to an accelerated carbonation process for 265 days. Polymeric material covered carbon steel electrodes in reduced state suffer a Fe gravimetric loss 15 times lower than the ones of bare electrodes against chlorides attack, due to the effect of physical barrier. Hybrid material covered electrodes in oxidised state after being submitted to a carbonation process suffer a Fe gravimetric loss 2.5 times lower than the ones of bare electrodes, due to galvanic protection provided by hybrid material polypyrrole/PW 12O403- on carbon steel.

  8. Experimental Study on the Electrochemical Anti-Corrosion Properties of Steel Structures Applying the Arc Thermal Metal Spraying Method.

    Science.gov (United States)

    Choe, Hong-Bok; Lee, Han-Seung; Shin, Jun-Ho

    2014-12-03

    The arc thermal metal spraying method (ATMSM) provides proven long-term protective coating systems using zinc, aluminum and their alloys for steel work in a marine environment. This paper focuses on studying experimentally the anti-corrosion criteria of ATMSM on steel specimens. The effects of the types of spraying metal and the presence or absence of sealing treatment from the thermal spraying of film on the anti-corrosion performance of TMSM were quantitatively evaluated by electrochemical techniques. The results showed that ATMSM represented a sufficient corrosion resistance with the driving force based on the potential difference of more than approximately 0.60 V between the thermal spraying layer and the base substrate steel. Furthermore, it was found that the sealing treatment of specimens had suppressed the dissolution of metals, increased the corrosion potential, decreased the corrosion current density and increased the polarization resistance. Metal alloy Al-Mg (95%:5%) by mass with epoxy sealing coating led to the most successful anti-corrosion performance in these electrochemical experiments.

  9. Electrochemical studies of adsorption and inhibitive performance of basic yellow 28 dye on mild steel corrosion in Acid solutions.

    Science.gov (United States)

    Ashassi-Sorkhabi, Habib; Asghari, Elnaz; Ejbari, Parisa

    2011-06-01

    Organic corrosion inhibitors are widely used to control the corrosion of different metals in various corrosive solutions. The inhibition performance of Basic yellow 28 (BY28) dye for mild steel corrosion was investigated in 0.1 M HCl solution and in a solution of 0.1 M HCl and 1% NaCl. Two electrochemical methods including Tafel polarization and electrochemical impedance spectroscopy (EIS) measurements were used. The corrosion parameters as well as inhibition efficiencies were obtained for different concentrations of inhibitor. The inhibition efficiencies showed that the BY28 dye acts as a good corrosion inhibitor for mild steel in both solutions. The studies on adsorption isotherm of the dye on mild steel proved that the adsorption of BY28 obeys the Langmuir adsorption isotherm. The average value of -ΔGads in both solutions was more than 20 and a little less than 40 kJ mol-1. Therefore, both chemisorption and physisorption phenomena were involved in the adsorption of the studied dye on mild steel surface.

  10. Electrochemical aspects on corrosion in Swedish reactor containments; Elektrokemiska aspekter paa korrosion i svenska reaktorinneslutningar

    Energy Technology Data Exchange (ETDEWEB)

    Ullberg, Mats [Studsvik Nuclear AB, SE-611 82 Nykoeping (Sweden)

    2006-10-15

    Post-stressed concrete is used in all Swedish nuclear reactor containments. Steel in concrete is normally protected from corrosion by the highly alkaline pore solution in concrete. A passive film develops on the surface of steel in contact with the pore solution. However, corrosion may still occur under special circumstances. It is therefore desirable to monitor the corrosion status of the containment. A review of the corrosion experience with steel in concrete strongly suggests that the potential problem of most concern for the Swedish reactor containments is cavity formation during grouting of tendons and of penetrations in the containment wall. Cavities break the contact between alkaline grout and steel. Corrosion is then possible, provided the relative humidity is high enough. Normal methods for inspection of the corrosion status of steel reinforcement in concrete are not applicable to very heavy structures like reactor containments. Since inspections are difficult to carry out, it is important that they be focused on the most susceptible portions of the containment. This report is an attempt to assemble potentially useful background information. The original intention was to focus on electrochemical methods of investigation. When it was realized that the potential use of electrochemical methods was limited, the scope of the review was broadened. The present as well as previous investigations indicate that nondestructive testing of grouted tendons is the outstanding problem in the condition assessment of Swedish nuclear reactor containments. Grouted tendons are also used in a very large number of bridges built since the early 1950s. The experience gained in connection with bridges has therefore been investigated. The need for a testing method for grouted tendons in bridges has long been strongly felt and development work has been in progress since the early 1970-ies, for example within the Strategic Highway Research Project in the Unite States. Potential

  11. Comparison between the corrosion forecast based on the potential measurement and the determination of the corrosion rate of the reinforcement bar by means of electrochemical techniques

    Directory of Open Access Journals (Sweden)

    Castaneda, A.

    2003-12-01

    Full Text Available The ASTA4 876-91 standard establishes a corrosion forecast of concrete reinforced bar by measuring the electrochemical potential. This forecast is based on thermodynamic considerations without taking into account the kinetic of the corrosion process. A comparison was made between the results obtained based on this standard and others using electrochemical techniques (Tafel, Rp, EIS, Electrochemical Noise. These techniques allows to obtain the corrosion rate in samples having 0.4, 0.5 and 0.66 water/cement ratios submitted to salt spray outdoors and by immersion in 3% saline solution during a test time of 20 months. Differences were detected between the results obtained using the ASTM standard and the electrochemical techniques used. The main difference is that samples submitted to immersion shows a higher probability of corrosion than samples submitted to salt spray; however, the electrochemical techniques showed the contrary concerning the corrosion kinetic process .A comparison respecting corrosion rate was also made between the results obtained by the different electrochemical techniques. It is very well known that all electrochemical techniques supposed always general corrosion except electrochemical noise. Using the technique the pitting index can be calculated. It shows that localized corrosion is the most predominant

    La norma ASTM 876-91 establece un pronóstico de corrosión de la barra de refuerzo del hormigón armado mediante la determinación de potenciales electroquímicos. Este pronóstico se basa en consideraciones termodinámicas, sin tener en cuenta la cinética del proceso de corrosión. Se comparan los resultados obtenidos aplicando esta norma con técnicas electroquímicas (Tafel, Rp, EIS, Ruido Electroquímico que permiten calcular la velocidad de corrosión en probetas con relaciones agua/cemento 0,4, 0,5 y 0,66 sometidas a niebla salina en condiciones naturales y en inmersión en solución salina al 3% durante un

  12. Corrosion behaviour of zirconium alloys in the autoclaves of Embalse nuclear power plant

    International Nuclear Information System (INIS)

    Bordoni, Roberto A.; Olmedo, Ana M.; Villegas, Marina; Miyagusuku, Marcela; Maroto, Alberto J. G.; Sainz, Ricardo A.; Fernandez, Alberto N.; Allemandi, Walter D.

    1999-01-01

    The corrosion behaviour of zirconium alloys coupons attached to the holders of the autoclaves located out of core in the primary circuit of Embalse nuclear power plant is described. The Zr-2.5 Nb coupons of the autoclaves at the higher temperature (305 C degrees) and the Zry-4 coupons of the autoclaves at 265 and 305 C degrees installed in 1988 had a normal corrosion behaviour, after 3500 of full power days. While, the Zr-2.5 Nb coupons, at 265 C degrees, showed the presence of white oxide nuclei and a weight gain indicating an abnormal corrosion behaviour which might be attributed to the material microstructure. Complementary tests, made in the period September 1991-April 1993, showed that the abnormal corrosion behaviour observed for the Canadian coupons installed in 1983 was due to a surface contamination of the Zry-4 coupons and due to the microstructure of the Zr-2.5 Nb coupons. The normal corrosion behaviour for both alloys installed in 1986, showed that the resin ingress to the primary circuit that occurred in 1988, do not affect the performance of these materials. (author)

  13. Evaluation of the Microbiologically Influenced Corrosion in a carbon steel making use of electrochemical techniques; Evaluacion de la corrosion microbiologica en un acero al carbono haciendo uso de tecnicas electroquimicas

    Energy Technology Data Exchange (ETDEWEB)

    Diaz S, A.C.; Arganis, C.; Ayala, V.; Gachuz, M.; Merino, J.; Suarez, S.; Brena, M.; Luna, P. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2001-07-01

    The Microbiologically Influenced Corrosion (MIC) has been identified as a problem of the nuclear plants systems in the last years. The electrochemical behavior of metal coupons of carbon steel submitted to the action of sulfate reducing bacteria (SRB) was evaluated, making use of the electrochemical techniques of direct current as well as electrochemical noise. The generated results show a little variation in the corrosion velocities which obtained by Tafel extrapolation and resistance to the linear polarization, whereas the electrochemical noise technique presented important differences as regards the registered behavior in environment with and without microorganisms. (Author)

  14. Development of self-powered wireless high temperature electrochemical sensor for in situ corrosion monitoring of coal-fired power plant.

    Science.gov (United States)

    Aung, Naing Naing; Crowe, Edward; Liu, Xingbo

    2015-03-01

    Reliable wireless high temperature electrochemical sensor technology is needed to provide in situ corrosion information for optimal predictive maintenance to ensure a high level of operational effectiveness under the harsh conditions present in coal-fired power generation systems. This research highlights the effectiveness of our novel high temperature electrochemical sensor for in situ coal ash hot corrosion monitoring in combination with the application of wireless communication and an energy harvesting thermoelectric generator (TEG). This self-powered sensor demonstrates the successful wireless transmission of both corrosion potential and corrosion current signals to a simulated control room environment. Copyright © 2014 ISA. All rights reserved.

  15. Corrosion behaviour of AISI 316L stainless-steel alloys in diabetic serum.

    Science.gov (United States)

    Moura e Silva, T; Monteiro, J M; Ferreira, M G; Vieira, J M

    1993-01-01

    The present study investigates the pitting-corrosion behaviour of AISI 316L stainless steel in human physiological fluids. The emphasis is on the effect of diabetic serum with glucose and proteins, but reference solutions of isotonic saline solution with and without antibiotics were also used. Polarization experiments were carried out, and the results point to the innocuity of those fluids on the performance of the alloy as far as pitting corrosion is concerned.

  16. The effect of hydrogen peroxide on the electrochemical behaviour of Ti-13Nb-13Zr alloy in Hanks' solution

    Directory of Open Access Journals (Sweden)

    Sérgio Luiz de Assis

    2006-12-01

    Full Text Available Titanium alloys are largely used for biomedical applications mainly due to their high corrosion resistance resulting from the protective oxide film formed on their surface. The literature, however, has pointed out discrepancies between in vitro tests and in vivo tests. These discrepancies have been ascribed to hydrogen peroxide (H2O2 generated by inflammatory reactions. In this investigation the electrochemical behaviour of a Ti-13Nb-13Zr alloy, which was developed as material for implants, has been evaluated in Hanks' solution, with and without H2O2. The evolution of the electrochemical behavior was monitored by electrochemical impedance spectroscopy (EIS and the results were fitted to an equivalent circuit that simulates an oxide film as a duplex layer structure composed of an inner barrier layer and an outer porous layer. In the solution without H2O2, the oxide film was very stable during the whole test period. On the other hand, in the solution with H2O2, the EIS results varied significantly, indicating a progressive decrease in the barrier layer resistance until 35 days which was followed by the restoration of the barrier layer protective characteristics against corrosion, either due to its growth or to its self-healing after partial consumption of the oxidant agent. The oxide film formed on the Ti alloy samples after 125 days of immersion in Hanks' solution, either with or without H2O2 was analyzed by XPS. The XPS results revealed the presence of TiO and TiO2 on the samples immersed in the two electrolytes, however, Ti2O3 was only found on the samples exposed to the H2O2 containing solution.

  17. Corrosion Behaviour of a Silane Protective Coating for NdFeB Magnets in Dentistry

    Directory of Open Access Journals (Sweden)

    Luigi Calabrese

    2015-01-01

    Full Text Available The corrosion behavior of coated and uncoated Ni/Cu/Ni rare earth magnets was assessed at increasing steps with a multilayering silanization procedure. Magnets’ durability was analyzed in Fusayama synthetic saliva solution in order to evaluate their application in dental field. Corrosion performance was evaluated by using polarization and electrochemical impedance spectroscopy in synthetic saliva solution up to 72 hours of continuous immersion. The results show that the addition of silane layers significantly improved anticorrosion properties. The coating and aging effects, in synthetic saliva solution, on magnetic field were evaluated by means of cyclic force-displacement curves.

  18. Electrochemical Behaviour of PACVD TiN-Coated CoCrMo Medical Alloy

    Directory of Open Access Journals (Sweden)

    Suzana Jakovljević

    2017-06-01

    Full Text Available CoCrMo alloys have been used in hip replacements for many years, and their properties can be enhanced with hard coatings. The TiN layer can be deposited on a CoCrMo alloy to its improve corrosion properties, such as reduction of the release of potentially harmful metal ions from CoCrMo-based surgical implants. In this work, a medical grade CoCrMo alloy was coated with TiN by means of plasma-assisted chemical deposition from the vapor phase (PACVD technique at 500 °C for 4.5 h. The TiN/substrate interface and thickness of the TiN layer were analysed by scanning electron microscopy (SEM. Corrosion parameters Ecor, Rp, and Icor were determined via direct current (DC and alternating current (AC electrochemical techniques. The SEM analysis showed a highly dense and quite uniform TiN layer, with a thickness of 2 µm. The results obtained by the DC electrochemical methods show better corrosion stability of the TiN/CoCrMo samples in comparison with CoCrMo in 0.9% NaCl at (25 ± 1 °C and (36 ± 1 °C. The electrochemical impedance spectroscopy (EIS results show that there are nuclei on the TiN coating which reduce the corrosion stability.

  19. Stainless steel surface biofunctionalization with PMMA-bioglass coatings: compositional, electrochemical corrosion studies and microbiological assay.

    Science.gov (United States)

    Floroian, L; Samoila, C; Badea, M; Munteanu, D; Ristoscu, C; Sima, F; Negut, I; Chifiriuc, M C; Mihailescu, I N

    2015-06-01

    A solution is proposed to surpass the inconvenience caused by the corrosion of stainless steel implants in human body fluids by protection with thin films of bioactive glasses or with composite polymer-bioactive glass nanostructures. Our option was to apply thin film deposition by matrix-assisted pulsed laser evaporation (MAPLE) which, to the difference to other laser or plasma techniques insures the protection of a more delicate material (a polymer in our case) against degradation or irreversible damage. The coatings composition, modification and corrosion resistance were investigated by FTIR and electrochemical techniques, under conditions which simulate their biological interaction with the human body. Mechanical testing demonstrates the adhesion, durability and resistance to fracture of the coatings. The coatings biocompatibility was assessed by in vitro studies and by flow cytometry. Our results support the unrestricted usage of coated stainless steel as a cheap alternative for human implants manufacture. They will be more accessible for lower prices in comparison with the majority present day fabrication of implants using Ti or Ti alloys.

  20. Electrochemical evaluation of inhibition efficiency of ciprofloxacin on the corrosion of copper in acid media

    Energy Technology Data Exchange (ETDEWEB)

    Thanapackiam, P. [Department of Chemistry, Coimbatore Institute of Technology, Coimbatore, Tamilnadu, 641 014 (India); Rameshkumar, Subramaniam [Department of Chemistry, Sri Vasavi College, Erode, Tamilnadu, 638 316 (India); Subramanian, S.S. [Department of Chemistry, PSG College of Technology, Coimbatore, Tamilnadu, 641 004 (India); Mallaiya, Kumaravel, E-mail: mkvteam.research@gmail.com [Department of Chemistry, PSG College of Technology, Coimbatore, Tamilnadu, 641 004 (India)

    2016-05-01

    The inhibition efficiency of ciprofloxacin on the corrosion of copper was studied in 1.0MHNO{sub 3} and 0.5MH{sub 2}SO{sub 4} solutions by electrochemical impedance spectroscopy and potentiodynamic polarization techniques. The corrosion inhibition action of ciprofloxacin was observed to be of mixed type in both the acid media, but with more of a cathodic nature. The experimental data were found to fit well with the Langmuir adsorption isotherm. The thermodynamic parameters such as adsorption equilibrium constant(K{sub ads}), free energy of adsorption(ΔG{sub ads}), activation energy(E{sub a}) and potential of zero charge(PZC) showed that the adsorption of ciprofloxacin onto copper surface involves both physisorption and chemisorption. - Highlights: • The inhibitor efficiency increases with increase in ciprofloxacin concentration. • Polarization measurements show that ciprofloxacin acts as a mixed type inhibitor. • The adsorption of the inhibitor on copper surface follows Langmuir adsorption isotherm. • The negative values of ΔG{sub ads} indicates that the adsorption is spontaneous and exothermic.

  1. Portable electrochemical system using screen-printed electrodes for monitoring corrosion inhibitors.

    Science.gov (United States)

    Squissato, André L; Silva, Weberson P; Del Claro, Augusto T S; Rocha, Diego P; Dornellas, Rafael M; Richter, Eduardo M; Foster, Christopher W; Banks, Craig E; Munoz, Rodrigo A A

    2017-11-01

    This work presents a portable electrochemical system for the continuous monitoring of corrosion inhibitors in a wide range of matrices including ethanol, seawater and mineral oil following simple dilution of the samples. Proof-of-concept is demonstrated for the sensing of 2,5-dimercapto-1,3,5-thiadiazole (DMCT), an important corrosion inhibitor. Disposable screen-printed graphitic electrodes (SPGEs) associated with a portable batch-injection cell are proposed for the amperometric determination of DMCT following sample dilution with electrolyte (95% v/v ethanol + 5% v/v 0.1molL -1 H 2 SO 4 solution). This electrolyte was compatible with all samples and the organic-resistant SPGE could be used continuously for more than 200 injections (100µL injected at 193µLs -1 ) free from effects of adsorption of DMCT, which have a great affinity for metallic surfaces, and dissolution of the other reported SPGE inks which has hampered prior research efforts. Fast (180h -1 ) and precise responses (RSD < 3% n = 10) with a detection limit of 0.3µmolL -1 was obtained. The accuracy of the proposed method was attested through recovery tests (93-106%) and the reasonable agreement of results of DMCT concentrations in samples analyzed by both proposed and spectrophotometric (comparative) methods. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Corrosion Measurements by Titration, (CMT). Alone or Combined With Electrochemical Measurements(EC). Examples: Corrosion of Zinc, Nickel, Aluminium and Iron

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers

    1998-01-01

    species or non-electrochemical dissolution reactions.A great number of examinations of corrosion has been made with the following metals: Zinc, nickel, aluminium and iron, as pure metals or alloys and also, with zinc, as post-treated electrodeposits.Limitations and restrictions in the use of CMT......At the corrosion potential the anodic dissolution of metal, Me = Me(z+) + z (e-), is accompanied by a cathodic reaction, z H(+) + z e(-) = z/2 H(2), for example. In order to maintain a constant pH-value addition of acid is needed, at a rate, which is equal to the rate of metal dissolution....... Measurement of the rate of addition of acid is then equivalent to a measurement of the rate of metal dissolution. By using a pH-stat and a simple PC-program the rate of corrosion can be measured continuously and very precisely; this is the basis for CMT measurements. Electrochemical measurements of corrosion...

  3. Corrosion fatigue behaviour of aluminium 5083-H111 welded using gas metal arc welding method

    CSIR Research Space (South Africa)

    Mutombo, K

    2011-12-01

    Full Text Available to the requirements of ASTM standards G31 [24] and G46 [25]. The 3.5% NaCl simulated sea water was prepared by dissolving 3.5 ? 0.1 parts by weight of Corrosion Fatigue Behaviour of Aluminium 5083-H111 Welded Using Gas Metal Arc Welding Method 193 NaCl in 96..., dissolve in some chemical solutions, such as strong acids or alkaline solutions. Damage to this passive layer in chloride-containing environments (such as sea water or NaCl solutions), may result in localised corrosive attack such as pitting corrosion...

  4. Crack growth and fracture behaviour of stress corrosion cracks of turbine generator steels

    International Nuclear Information System (INIS)

    Berger; Vahle.

    1989-01-01

    The object of this investigation was the quantifying of the behaviour of cracks which were induced during service under corrosive media. To investigate the influence of stress corrosion crack configurations on stress intensity factor, six different test materials from 2 and 3.5% NiCrMoV and 2% Cr/1% Ni steels were chosen. The stress corrosion cracks were induced at wedge loaded compact tension specimens in a corrosive media in the laboratory. Fracture mechanics tests as well as fatigue crack growth tests were performed at these specimens. All stress corrosion cracks have an intercrystalline path and a crack length longer than 1 mm; they are multiple and have branched cracks tips. The fracture mechanics tests at these stress corrosion cracks induced in the laboratory and during service of components show that their stress intensity factor is 30 to 70% smaller than the stress intensity factor calculated for single straight cracks too. Theoretical calculations arrived to the same results. Crack initiation and growth behaviour under cyclic loading starting from these stress corrosion cracks results in that the load or the stress intensity range ΔK has to be increased three times larger than the ΔK-threshold value to induce crack initiation. The crack growth velocity influenced by multiple crack tips and multiple growing cracks from these crack tips is much lower than the crack growth velocity of a normal fatigue crack (one crack tip). (orig./MM) With 32 figs

  5. Electrochemical removal and recovery of iron from groundwater using non-corrosive electrodes.

    Science.gov (United States)

    Nguyen, Van Khanh; Ahn, Yeonghee

    2018-04-01

    Iron contamination in groundwater has attracted much attention from environmentalists and government agencies because it can cause many problems in human life and in industrial and agricultural activities when groundwater is directly used without any treatment. This study aims to investigate the electrochemical oxidation of Fe(II) to Fe(III) and recovery of insoluble Fe(III) using non-corrosive graphite electrode which serves as a controllable, low-cost, low maintenance and virtually unlimited electron acceptor for Fe(II) oxidation. The lab-scale results indicated that Fe(II) removal up to 100% was obtained at an applied voltage higher than 2 V. The Fe(II) removal efficiency was linearly increased with the increase of potential supply in the range of 1-4 V in the salinity 0.5%. The Fe(II) removal rate could no longer be enhanced at the applied potential higher than 8 V in the condition without salinity. The results from SEM-EDS and XRD revealed that Fe was recovered as FeOOH by conventional filtration with a recovery efficiency of 82.7-92.1%. The electrochemical Fe(II) removal might be an alternative for the conventional method of the in situ Fe removal from groundwater. Besides, the recovered FeOOH can be used as a raw material for environmental remediation and pigment industry. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Electrochemical Methods for the Intergranular Corrosion Property Evaluation of Stainless Steels

    International Nuclear Information System (INIS)

    Lee, Jung Bok

    1987-01-01

    For the last fifteen years, the Electrochemical Potentiokinetic Reactivation (EPR) method, an electrochemical method, has been actively investigated for use in determining the degree of sensitization (DOS) in stainless steels (a metallurgical structure susceptible to intergranular corrosion). One of the reasons for this active investigation was due to the fact that the technique may be usable for field nondestructive measurements of DOS in stainless steels. In this paper, a brief overview of the technique, including the advantages and limitations, is discussed. Then, a new test method which is able to detect the sensitized metallurgical structures nondestructively after field welding is introduced. This new nondestructive method is a modification of the ASTM A262-A (the oxalic acid etch test). The improved test method employs a 30 second etching in a 10% oxalic acid solution under an anodic current density of 1 ampere per square centimeter at the temperatures above 60 .deg. C. Between 50 and 60 .deg. C the thirty second etching test should be used first. When the thirty second etching shows an under etched grain boundary, the etching time should be increased to ninety seconds. At temperatures below 50 .deg. C the ninety second etching, as described in ASTM A 262-A, should be employed. This improved test method can be used in the temperature range of 0 and 100 .deg. C

  7. In situ soft X-ray absorption spectroscopy investigation of electrochemical corrosion of copper in aqueous NaHCO3 solution

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Peng; Chen, Jeng-Lung; Borondics, Ferenc; Glans, Per-Anders; West, Mark W.; Chang, Ching-Lin; Salmeron, Miquel; Guo, Jinghua

    2010-03-31

    A novel electrochemical setup has been developed for soft x-ray absorption studies of the electronic structure of electrode materials during electrochemical cycling. In this communication we illustrate the operation of the cell with a study of the corrosion behavior of copper in aqueous NaHCO3 solution via the electrochemically induced changes of its electronic structure. This development opens the way for in situ investigations of electrochemical processes, photovoltaics, batteries, fuel cells, water splitting, corrosion, electrodeposition, and a variety of important biological processes.

  8. Microstructure and electrochemical corrosion behavior of a Pb-1 wt%Sn alloy for lead-acid battery components

    Energy Technology Data Exchange (ETDEWEB)

    Peixoto, Leandro C.; Osorio, Wislei R.; Garcia, Amauri [Department of Materials Engineering, University of Campinas - UNICAMP, PO Box 612, 13083-970, Campinas - SP (Brazil)

    2009-07-15

    The aim of this study was to evaluate the effect of solidification cooling rates on the as-cast microstructural morphologies of a Pb-1 wt%Sn alloy, and to correlate the resulting microstructure with the corresponding electrochemical corrosion resistance in a 0.5 M H{sub 2}SO{sub 4} solution at 25 C. Cylindrical low-carbon steel and insulating molds were employed permitting the two extremes of a significant range of solidification cooling rates to be experimentally examined. Electrochemical impedance spectroscopy (EIS) diagrams, potentiodynamic polarization curves and an equivalent circuit analysis were used to evaluate the electrochemical corrosion response of Pb-1 wt%Sn alloy samples. It was found that lower cooling rates are associated with coarse cellular arrays which result in better corrosion resistance than fine cells which are related to high cooling rates. The experimental results have shown that that the pre-programming of microstructure cell size of Pb-Sn alloys can be used as an alternative way to produce as-cast components of lead-acid batteries with higher corrosion resistance. (author)

  9. Electrochemical corrosion study of Mg–Al–Zn–Mn alloy in aqueous ethylene glycol containing chloride ions

    Directory of Open Access Journals (Sweden)

    Harish Medhashree

    2017-01-01

    Full Text Available Nowadays most of the automobiles use magnesium alloys in the components of the engine coolant systems. These engine coolants used are mainly composed of aqueous ethylene glycol along with some inhibitors. Generally the engine coolants are contaminated by environmental anions like chlorides, which would enhance the rate of corrosion of the alloys used in the coolant system. In the present study, the corrosion behavior of Mg–Al–Zn–Mn alloy in 30% (v/v aqueous ethylene glycol containing chloride anions at neutral pH was investigated. Electrochemical techniques, such as potentiodynamic polarization method, cyclic polarization and electrochemical impedance spectroscopy (EIS were used to study the corrosion behavior of Mg–Al–Zn–Mn alloy. The surface morphology, microstructure and surface composition of the alloy were studied by using the scanning electron microscopy (SEM, optical microscopy and energy dispersion X-ray (EDX analysis, respectively. Electrochemical investigations show that the rate of corrosion increases with the increase in chloride ion concentration and also with the increase in medium temperature.

  10. Brief description of out-of-pile test facilities for study in corrosion and fission product behaviour in flowing sodium

    International Nuclear Information System (INIS)

    Iizawa, K.; Sekiguchi, N.; Atsumo, H.

    1976-01-01

    The experimental methods to perform tests for study in corrosion and fission products behaviour in flowing sodium are outlined. Flow diagrams for the activated materials and fission products behaviour test loop are given

  11. Frequency-dependent alternating-current scanning electrochemical microscopy (4D AC-SECM) for local visualisation of corrosion sites.

    Science.gov (United States)

    Eckhard, Kathrin; Erichsen, Thomas; Stratmann, Martin; Schuhmann, Wolfgang

    2008-01-01

    For a better understanding of the initiation of localised corrosion, there is a need for analytical tools that are capable of imaging corrosion pits and precursor sites with high spatial resolution and sensitivity. The lateral electrochemical contrast in alternating-current scanning electrochemical microscopy (AC-SECM) has been found to be highly dependent on the frequency of the applied alternating voltage. In order to be able to obtain data with optimum contrast and high resolution, the AC frequency is swept in a full spectrum at each point in space instead of performing spatially resolved measurements at one fixed perturbation frequency. In doing so, four-dimensional data sets are acquired (4D AC-SECM). Here, we describe the instrument set-up and modus operandi, along with the first results from the imaging of corroding surfaces. Corrosion precursor sites and local defects in protective organic coatings, as well as an actively corroding pit on 304 stainless steel, have been successfully visualised. Since the lateral electrochemical contrast in these images varies with the perturbation frequency, the proposed approach constitutes an indispensable tool for obtaining optimum electrochemical contrast.

  12. Effect of Different Welding Processes on Electrochemical and Corrosion Behavior of Pure Nickel in 1 M NaCl Solution

    Directory of Open Access Journals (Sweden)

    Xijing Wang

    2017-11-01

    Full Text Available A plasma arc welding (PAW-tungsten inert gas (TIG hybrid welding process is proposed to weld pure nickel. In PAW-TIG welding, the arc of the PAW was first to be ignited, then TIG was ignited, while in PAW welding, only the PAW arc was launched. This paper investigated the effect of different welding processes on electrochemical and corrosion performance of between a pure nickel joint and a base metal in an aerated 1 M NaCl solution, respectively. The average grain size of the joint fabricated by PAW welding (denoted as JP joint is 463.57 μm, the joint fabricated by PAW-TIG welding(denoted as JP-T joint is 547.32 μm, and the base metal (BM is 47.32 μm. In this work, the passivity behaviors of samples were characterized for two welding processes by electrochemical impedance spectroscopy (EIS, open circuit potential versus immersion time (OCP-t, and the potentiodynamic polarization plots. EIS spectra, attained with different immersion times, were analyzed and fitted by an equivalent electrical circuit. Photomicrographs of BM, JP, and JP-T were also taken with a scanning electron microscope (SEM to reveal the morphological structure of the pit surfaces. Electrochemical tests show that the sequence of the corrosion resistance is BM > JP > JP-T. The size and quantity of the hemispherical corrosion pits of all samples are different. The corrosion morphology observations found a consistency with the consequence of the electrochemical measurements. The results show that an increase of the grain dimensions due to different heat treatments decreased the pure nickel stability to pitting corrosion.

  13. Time-dependent electrochemical characterization of the corrosion of a magnesium rare-earth alloy in simulated body fluids.

    Science.gov (United States)

    Rettig, Ralf; Virtanen, Sannakaisa

    2008-04-01

    The electrochemistry of the corrosion process of a magnesium rare-earth-alloy is studied in detail in simulated body fluid (m-SBF) over the first 5 days. The aim is to investigate the corrosion mechanism under in vitro conditions. For this purpose we also used electrolytes that contain only some of the components of SBF, they were compared to SBF to investigate the influence of the different ions in SBF. The influence of albumin on the corrosion process was studied with a solution containing m-SBF and albumin in physiological concentration. For this study, impedance spectroscopy series measurements were performed. Additional results were gained from polarization curves. We conclude from the study that the corrosion resistance is significantly lower in m-SBF than in simple isotonic NaCl-solution. Albumin may form a blocking layer on the surface in the first hours of exposure. The formed corrosion layers consisting of amorphous apatite have only a low protective ability. Further results show that the corrosion processes in SBFs follow a linear time-law. The results elucidate critical factors and mechanisms of the electrochemical corrosion process of magnesium rare-earth alloys in SBFs, this understanding is crucial for a successful application of Mg alloys in biomedical applications. Copyright 2007 Wiley Periodicals, Inc.

  14. Corrosion behaviour of unalloyed steel in Portland cement

    International Nuclear Information System (INIS)

    Grauer, R.

    1988-04-01

    The production of hydrogen can cause problems in a repository for low and intermediate level waste. Since the production of gas is mainly due to the corrosion of unalloyed steel, it is important to have as reliable data as possible for the corrosion rate in anaerobic cement. A review of the literature shows that the corrosion current densities are in the range of 0.01 to 0.1 μA/cm 2 (corresponding to corrosion rates between 0.1 and 1.2 μm/a). This implies hydrogen production rates between 0.022 and 0.22 mol/(m 2 a). Corrosion rates of the abovementioned order of magnitude are technically irrelevant, so that there is little interest in determining them accurately. Furthermore, their determination entails problems of measurement technique. In the present situation it would therefore appear risky to accept the lower value as proven. Experiments are proposed to reduce the present uncertainty. (author) 35 refs., 10 figs

  15. Corrosion behaviour of unalloyed steel in Portland cement

    International Nuclear Information System (INIS)

    Grauer, R.

    1988-01-01

    The production of hydrogen can cause problems in a repository for low and intermediate level waste. Since the production of gas is mainly due to the corrosion of unalloyed steel, it is important to have as reliable data as possible for the corrosion rate in anaerobic cement. A review of the literature shows that the corrosion current densities are in the range of 0.01 to 0.1 μA/cm 2 (corresponding to corrosion rates between 0.1 and 1.2 μm/a). This implies hydrogen production rates between 0.022 and 0.22 mol/(m 2 xa). Corrosion rates of the abovementioned order of magnitude are technically irrelevant, so that there is little interest in determining them accurately. Furthermore, their determination entails problems of measurement technique. In the present situation it would therefore appear risky to accept the lower value as proven. Experiments are proposed to reduce the present uncertainty. (author) 35 refs., 10 figs

  16. The corrosion behaviour of carbon steel in Portland cement

    International Nuclear Information System (INIS)

    Grauer, R.

    1988-01-01

    The production of hydrogen can cause problems in a repository for low- and intermediate-level waste. Since gas production is mainly due to the corrosion of carbon steel, it is important to have as reliable data as possible on the corrosion rate of steel in anaerobic cement. A review of the literature shows that the corrosion current densities lie in the range 0.01 to 0.1 μA/cm 2 (corresponding to corrosion rates between 0.1 and 1.2 μm/a). This implies hydrogen production rates between 0.022 and 0.22 mol/(m 2 .a). Corrosion rates of this order of magnitude are technically irrelevant, with the result that there is very little interest in determining them accurately. Furthermore, their determination entails problems of measurement technique. Given the current situation, it would appear somewhat risky to accept the lower value for hydrogen production as proven. Proposals are made for experiments which would reduce this element of uncertainty. (author) 10 figs., 35 refs

  17. Corrosion Resistance and Pitting Behaviour of Low-Carbon High-Mn Steels in Chloride Solution

    Directory of Open Access Journals (Sweden)

    Grajcar A.

    2016-06-01

    Full Text Available Corrosion resistance of the X4MnSiAlNbTi27-4-2 and X6MnSiAlNbTi26-3-3 type austenitic steels, after hot deformation as well as after cold rolling, were evaluated in 3.5% NaCl solution using potentiodynamic polarization tests. A type of nonmetallic inclusions and their pitting corrosion behaviour were investigated. Additionally, the effect of cold deformation on the corrosion resistance of high-Mn steels was studied. The SEM micrographs revealed that corrosion damage formed in both investigated steels is characterized by various shapes and an irregular distribution at the metallic matrix, independently on the steel state (thermomechanically treated or cold worked. Corrosion pits are generated both in grain interiors, grain boundaries and along the deformation bands. Moreover, corrosion damage is stronger in cold deformed steels in comparison to the thermomechanically treated specimens. EDS analysis revealed that corrosion pits preferentially nucleated on MnS and AlN inclusions or complex oxysulphides. The morphology of corrosion damage in 3.5% NaCl supports the data registered in potentiodynamic tests.

  18. Corrosion

    Science.gov (United States)

    Slabaugh, W. H.

    1974-01-01

    Presents some materials for use in demonstration and experimentation of corrosion processes, including corrosion stimulation and inhibition. Indicates that basic concepts of electrochemistry, crystal structure, and kinetics can be extended to practical chemistry through corrosion explanation. (CC)

  19. Electrochemical, Polarization, and Crevice Corrosion Testing of Nitinol 60, A Supplement to the ECLSS Sustaining Materials Compatibility Study

    Science.gov (United States)

    Lee, R. E.

    2016-01-01

    In earlier trials, electrochemical test results were presented for six noble metals evaluated in test solutions representative of waste liquids processed in the Environmental Control and Life Support System (ECLSS) aboard the International Space Station (ISS). Subsequently, a seventh metal, Nitinol 60, was added for evaluation and subjected to the same test routines, data analysis, and theoretical methodologies. The previous six test metals included three titanium grades, (commercially pure, 6Al-4V alloy and 6Al-4V low interstitial alloy), two nickel-chromium alloys (Inconel(RegisteredTrademark) 625 and Hastelloy(RegisteredTrademark) C276), and one high-tier stainless steel (Cronidur(RegisteredTrademark) 30). The three titanium alloys gave the best results of all the metals, indicating superior corrosive nobility and galvanic protection properties. For this current effort, the results have clearly shown that Nitinol 60 is almost as noble as titanium, being very corrosion-resistant and galvanically compatible with the other six metals electrochemically and during long-term exposure. is also quite noble as it is very corrosion resistant and galvanically compatible with the other six metals from both an electrochemical perspective and long-term crevice corrosion scenario. This was clearly demonstrated utilizing the same techniques for linear, Tafel and cyclic polarization, and galvanic coupling of the metal candidate as was done for the previous study. The high nobility and low corrosion susceptibility for Nitinol 60 appear to be intermediate to the nickel/chromium alloys and the titanium metals with indications that are more reflective of the titanium metals in terms of general corrosion and pitting behavior.

  20. Corrosion behaviour of aluminium plates in aqueous medium

    International Nuclear Information System (INIS)

    Oliveira, M.F. de; Gaio, J.C.

    1985-01-01

    The process of corrosion concerning the aluminium 1050 plate was studied at room temperatures, 45 and 60 0 C in deionized water, the same Argonauta Reactor Water. Beyond the temperature influence, it was verified the effect of chloride ion and oxygen. It ws found that the amount of oxyde formed at room temperatures is almost negligible; at 45 and 60 0 C the samples were covered with bayerita, the quantity of oxide formed at 45 0 C being higher than at 60 0 C. It was observed that there will be risk of corrosion in the case of Reactor Water to undergo contamination with chloride ions. The results have shown that the material can be used since the medium don't be strongly oxidizing. At potentials higher than - 900M sup(V) ess (-280 m sup(V) sub(H)), the material will undergo pitting corrosion. (Author) [pt

  1. Corrosion behaviour of materials selected for FMIT lithium system

    Energy Technology Data Exchange (ETDEWEB)

    Bazinet, G.D.; Brehm, W.F.

    1983-09-01

    The corrosion behavior of selected materials in a liquid lithium environment was studied in support of system and component designs for the Fusion Materials Irradiation Test (FMIT) Facility. Testing conditions ranged from about 3700 to about6500 hours of exposure to flowing lithium at temperatures from 230/sup 0/ to 270/sup 0/C and static lithium at temperatures from 200/sup 0/ to 500/sup 0/C. Principal areas of investigation included lithium corrosion/erosion effects on FMIT lithium system baseline and candidate materials. Material coupons and full-size prototypic components were evaluated to determine corrosion rates, fatigue crack growth rates, structural compatibility, and component acceptability for the lithium system. Based on the results of these studies, concerns regarding system materials and component designs were satisfactorily resolved to support a 20-year design life requirement for the FMIT lithium system.

  2. Corrosion behaviour of materials selected for FMIT lithium system

    International Nuclear Information System (INIS)

    Bazinet, G.D.; Brehm, W.F.

    1983-01-01

    The corrosion behavior of selected materials in a liquid lithium environment was studied in support of system and component designs for the Fusion Materials Irradiation Test (FMIT) Facility. Testing conditions ranged from about 3700 to about6500 hours of exposure to flowing lithium at temperatures from 230 0 to 270 0 C and static lithium at temperatures from 200 0 to 500 0 C. Principal areas of investigation included lithium corrosion/erosion effects on FMIT lithium system baseline and candidate materials. Material coupons and full-size prototypic components were evaluated to determine corrosion rates, fatigue crack growth rates, structural compatibility, and component acceptability for the lithium system. Based on the results of these studies, concerns regarding system materials and component designs were satisfactorily resolved to support a 20-year design life requirement for the FMIT lithium system

  3. Electrochemical corrosion of Pb-1 wt% Sn and Pb-2.5 wt% Sn alloys for lead-acid battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Osorio, Wislei R.; Peixoto, Leandro C.; Garcia, Amauri [Department of Materials Engineering, State University of Campinas - UNICAMP, PO Box 612, 13083-970 Campinas, SP (Brazil)

    2009-12-01

    The aim of this study was to compare the electrochemical corrosion behavior of as-cast Pb-1 wt% Sn and Pb-2.5 wt% Sn alloy samples in a 0.5 M H{sub 2}SO{sub 4} solution at 25 C. A water-cooled unidirectional solidification system was used to obtain the as-cast samples. Electrochemical impedance spectroscopy (EIS) diagrams, potentiodynamic polarization curves and an equivalent circuit analysis were used to evaluate the electrochemical corrosion response. It was found that a coarse cellular array has a better electrochemical corrosion resistance than fine cells. The pre-programming of microstructure cell size of Pb-Sn alloys can be used as an alternative way to produce as-cast components of lead-acid batteries with higher corrosion resistance associated with environmental and economical aspects. (author)

  4. ELECTROCHEMICAL CORROSION TESTING OF TANKS 241-AN-102 & 241-AP-107 & 241-AP-108 IN SUPPORT OF ULTRASONIC TESTING

    Energy Technology Data Exchange (ETDEWEB)

    WYRWAS RB; DUNCAN JB

    2008-11-20

    This report presents the results of the corrosion rates that were measured using electrochemical methods for tanks 241-AN-102 (AN-102), 241-AP-107 (AP 107), and 241-AP-108 (AP-108) performed under test plant RPP-PLAN-38215. The steel used as materials of construction for AN and AP tank farms was A537 Class 1. Test coupons of A537 Class 1 carbon steel were used for corrosion testing in the AN-107, AP-107, and AP-108 tank waste. Supernate will be tested from AN-102, AP-107, and Ap-108. Saltcake testing was performed on AP-108 only.

  5. Electrochemical Study of Unmodified and Inhibitor Doped Silane Films for Corrosion Protection of AA2024-T3

    Science.gov (United States)

    Mubarak, Nauman; Hu, Jin; Tang, Shawei

    2017-09-01

    Aluminum alloy was coated with unmodified and rare-earth inhibitor doped silane films. The role of number of hydrolysable groups, functional group and cerium ions towards film protective quality was investigated. The anti-corrosion performance was evaluated using electrochemical impedance spectroscopy (EIS), d.c. potentiodynamic polarization and energy dispersive x-ray spectroscopy (EDS). The morphology was studied using scanning electron microscopy (SEM). Results indicate improved corrosion protection performance especially for cerium modified silane films with higher number of hydrolysable groups. Inhibitor doped silanes present a facile method for pre-treatment of aluminium alloys prior to deposition of top coat.

  6. Enhanced Corrosion Resistance of Carbon Steel in Hydrochloric Acid Solution by Eriobotrya Japonica Thunb. Leaf Extract: Electrochemical Study.

    Science.gov (United States)

    Yang, Wenjing; Wang, Qihui; Xu, Ke; Yin, Yanjun; Bao, Hebin; Li, Xueming; Niu, Lidan; Chen, Shiqi

    2017-08-16

    The biodegradable inhibitors, which could effectively reduce the rate of corrosion of carbon steel, were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The mixed-type inhibitors extracted from Eriobotrya japonica Thunb. leaf exhibited excellent inhibition performance, and the inhibition efficiency for carbon steel reached 90.0% at 298 K in hydrochloric acid. Moreover, the adsorption mechanism of the inhibitors on a carbon steel surface is described by the Langmuir adsorption isotherm. Simultaneously, the corrosion morphology of the carbon steel and the inhibitor structure were analyzed by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively.

  7. Corrosion behaviour of some conventional stainless steels in electrolyzing process

    Directory of Open Access Journals (Sweden)

    Amal NASSAR

    2015-12-01

    Full Text Available In this study, attempts were made to increase the amount of hydrogen generated from the water electrolysis process. Some conventional stainless steels (316; 409; 410 and 430 were used as anode and cathode in electrolysis process. Further study was carried out on the corrosion trend in all the investigated metals. It is observed that the electrode material can effect on the amount of hydrogen generate by electrolyzing process and metal composition of the stainless steels effects on the rate of corrosion.

  8. Corrosion resistance of zirconium: general mechanisms, behaviour in nitric acid

    International Nuclear Information System (INIS)

    Pinard Legry, G.

    1990-01-01

    Corrosion resistance of zirconium results from the strong affinity of this metal for oxygen; as a result a thin protective oxide film is spontaneously formed in air or aqueous media, its thickness and properties depending on the physicochemical conditions at the interface. This film passivates the underlying metal but obviously if the passive film is partially or completely removed, localised or generalised corrosion phenomena will occur. In nitric acid, this depassivation may be chemical (fluorides) or mechanical (straining, creep, fretting). In these cases it is useful to determine the physicochemical conditions (concentration, temperature, potential, stress) which will have to be observed to use safely zirconium and its alloys in nitric acid solutions [fr

  9. Corrosion behaviour of construction materials for high temperature water electrolysers

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey

    2010-01-01

    Different types of corrosion resistant stainless steels, Ni-based alloys as well as titanium and tantalum were evaluated as a possible metallic bipolar plate and construction material with respect to corrosion resistance under simulated conditions corresponding to the conditions in high temperature...... proton exchange membrane (PEM) water electrolysers (HTPEMWE). All samples were exposed to anodic polarisation in 85% phosphoric acid electrolyte solution. Platinum and gold plates were tested for the valid comparison. Steady-state voltammetry was used in combination with scanning electron microscopy...

  10. Synthesis of recent investigations on corrosion behaviour of radioactive waste glasses

    International Nuclear Information System (INIS)

    Grauer, R.

    1985-03-01

    By way of a supplement to an earlier report (NTB 83-01, EIR-Report Nr. 477), work which has appeared in the meantime on the corrosion behaviour of borosilicate glasses as a solidification matrix for high-level radioactive waste has been evaluated. Many works have confirmed that for a particular glass, besides temperature and pH-value, the silicate concentration of the solution exerts the strongest influence on corrosion rate. The effect of silicate can be described in terms of simple reaction kinetic models which provides a more sound basis for prediction of longterm behaviour of glasses than previously existed. Meanwhile, the effects of backfill- and canister-materials and their corrosion products have been given the attention they merit. These materials affect glass corrosion primarily through regulation of silicic acid concentration. A particular finding which is of interest is the strong inhibition of glass corrosion by lead ions. Stationary corrosion rates in the order of magnitude of 10 -5 g/cm 2 ·d can be derived from long-term corrosion experiments in stagnant water at 90 C. At the envisaged repository temperature of 55 C they will be one to two orders of magnitude less. The effects of radioactive decay on corrosion rate are either very small or not detectable at all. No further new viewpoints have been put forward with regard to a possible thermal re-structuring of glasses under repository conditions: re-crystallisation (devitrification) is not to be feared. With regard to future experiments, further work on quantification of the effects of canister- and backfill-materials and experiments with corrosion inhibitors would be of primary interest. (author)

  11. Electrochemical corrosion investigations on austenitic CrNi-steels in nitric acid with and without additions of metal ions

    International Nuclear Information System (INIS)

    Simon, R.

    1988-04-01

    The aim of the present work was to develop an electrochemical short-time test procedure for detecting intergranular corrosion (IGC) susceptibility of austenitic CrNi-steels in strongly oxidizing media, as e.g. concentrated nitric acid. This procedure should cover the test parameters of the usually applied ASTM Standard Huey Test, which is performed in boiling 14.4 n nitric acid. The described electrochemical test procedure - a potentiostatic polarisation of steel specimens in the transpassive range - is presented as an alternative to the Huey Test with equivalent results, but with a reduced testing time. (orig./IHOE) [de

  12. High temperature cyclic oxidation and hot corrosion behaviours of ...

    Indian Academy of Sciences (India)

    Administrator

    based superalloys have been investigated at 900°C in air with or without. Na2SO4–60% V2O5 coatings on the superalloy specimens in the present work. The kinetics of corrosion of super- alloy substrates was determined from the weight change.

  13. Effect of anodization on corrosion behaviour and biocompatibility of ...

    Indian Academy of Sciences (India)

    The objective of this investigation is to study the effectiveness of anodized surface of commercial purity titanium (Cp-Ti) on ... aids. It has attractive bulk mechanical properties like low modulus of elasticity, high strength to weight ratio, excellent corrosion resistance, low rate of ion release combined with excellent biostability ...

  14. Electrochemical investigation into inclination of the zone of the thermal influence of the 06KhN28MDT alloy welded joint to intercrystalline corrosion

    International Nuclear Information System (INIS)

    Masin, M.M.; Knyazheva, V.M.; Medvedeva, L.A.; Kuzmak, E.M.; Karmazinov, N.P.

    1979-01-01

    Using electrochemical methods in 22n HClOsub(4)+0.8n NaCl the effect of simulated heat on the trend to intercrystalline corrosion (ICC) of certain regions of thermal influence zone of the 06KhN28MDT alloy welded joints has been studied. Anode behaviour of specimens with different trends to ICC was studied. It is shown, that the anode current density with constant potential in transient and passive regions depends on heat temperature, linear energy and a rate of the following heating of specimens. Maximum resistance of welded joints simultaneously in all the temperature regions with the most likelihood can be achieved when using electric-arc welding with accelerated cooling of welded joint

  15. Aqueous corrosion behaviour of Zr-1 Nb and Zr-20 Nb with different heat treatments

    International Nuclear Information System (INIS)

    Jaime Solis, F.; Bordoni, Roberto; Olmedo, Ana M.; Villegas, Marina; Miyagusuku, Marcela

    2003-01-01

    The corrosion behaviour of Zr-1 Nb and Zr-20 Nb coupons annealed at 850 C degrees during 1 hour and afterwards aged at different temperatures and time periods was studied. The Zr-1 Nb samples were aged at 400 and 500 C degrees and the Zr-20 Nb samples at 265 and 550 C degrees. The results have shown that ageing increases the corrosion resistance because the aged microstructure is somewhat closer to the equilibrium one. This was not the case of Zr-1 Nb aged 72 hs at 400 C degrees. The presence of the ω-phase does not have a deleterious effect in the corrosion behaviour of Zr-20 Nb. Also, an ageing of 2200 h at 265 C degrees induced a relevant decrease in the corrosion rate of Zr-20 Nb indicating a decomposition of the β- Zr phase. This effect was observed at the inlet of pressure tubes in CANDU reactors. The results obtained will be used to establish the relative importance of the α-Zr and β-Zr phases in the corrosion behaviour of pressure tubes. (author)

  16. Theoretical, thermodynamic and electrochemical analysis of biotin drug as an impending corrosion inhibitor for mild steel in 15% hydrochloric acid

    Science.gov (United States)

    Xu, Xihua; Sun, Zhipeng; Ansari, K. R.; Lin, Yuanhua

    2017-01-01

    The corrosion mitigation efficiency of biotin drug for mild steel in 15% hydrochloric acid was thoroughly investigated by weight loss and electrochemical methods. The surface morphology was studied by the contact angle, scanning electrochemical microscopy, atomic force microscopy and scanning electron microscopy methods. Quantum chemical calculation and Fukui analysis were done to correlate the experimental and theoretical data. The influence of the concentration of inhibitor, immersion time, temperature, activation energy, enthalpy and entropy has been reported. The mitigation efficiency of biotin obtained by all methods was in good correlation with each other. Polarization studies revealed that biotin acted as a mixed inhibitor. The adsorption of biotin was found to obey the Langmuir adsorption isotherm. Surface studies showed the hydrophobic nature of the steel with inhibitor and vindicated the formation of a film on the metal surface that reduced the corrosion rate. PMID:29308235

  17. Corrosion behaviour of electropolished AISI 316L austenitic biomaterial in physiological solution

    Science.gov (United States)

    Zatkalíková, V.; Markovičová, L.; Škorvanová, M.

    2017-11-01

    Due to suitable mechanical properties, satisfactory corrosion resistance and relatively low cost, austenitic stainless steels are important biomaterials for manufacture of implants and various medical instruments and devices. Their corrosion properties and biocompatibility are significantly affected by protective passive surface film quality, which depends on used mechanical and chemical surface treatment. This article deals with corrosion resistance of AISI 316L stainless steel, which is the most widely used Cr-Ni-Mo austenitic biomaterial. Corrosion behaviour of five various surfaces (original, electropolished, three surfaces with combined treatment finished by electropolishing) is evaluated on the bases of cyclic potentiodynamic polarization tests performed in physiological solution at the temperature of 37± 0.5 °C.

  18. Electrochemical properties of corrosion products formed on Zn-Mg, Zn-Al and Zn-Al-Mg coatings in model atmospheric conditions

    Czech Academy of Sciences Publication Activity Database

    Stoulil, J.; Prošek, T.; Nazarov, A.; Oswald, Jiří; Kříž, P.; Thierry, D.

    2015-01-01

    Roč. 66, č. 8 (2015), s. 777-782 ISSN 0947-5117 Institutional support: RVO:68378271 Keywords : corrosion products * electrochemical properties * zinc coating Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.450, year: 2015

  19. Measurement of electrochemical noise for the study of corrosion processes of metallic alloys; Medida de ruido electroquimico para el estudio de rocesoso de corrosion de aleaciones metalicas

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Amaya, J. M.; Bethencourt, M.; Gonzalez-Rovira, L.; Botana, F. J.

    2009-07-01

    Electrochemical noise (EN) is a technique that allows the estimation of both the rate and the corrosion mechanism of different metallic alloys by means of the measurement and the analysis of the fluctuations of current and voltage. Its main advantage against other electrochemical techniques is that during the measurement process, the corrosive systems under study are not instrumentally disturbed, and therefore, the systems are kept at their natural corrosion potential. Two steps are necessary to use this technique: measurement and analysis of the EN signals. In this paper, the most important concepts related only to the measurement of EN are revised. The parameters most employed in the literature to analyse the EN signals will be described in another paper. In the present article, the experimental devices normally used to measure EN signals are firstly analysed. Subsequently, the most important properties of the EN signals are studied. Finally, the external sources of instrumental noise that can affect to the EN signals are described. (Author) 65 refs.

  20. Effect of stress corrosion cracking at various strain rates on the electrochemical corrosion behavior of Mg-Zn-In-Sn alloy.

    Science.gov (United States)

    Yu, Zhan; Ju, Dongying; Zhao, Hongyang

    2013-12-01

    This study is aimed to determine the effect of stress corrosion with low strain rates on the electrochemical properties of alloy electrode. Stress corrosion cracking tests of Mg-Zn-In-Sn alloy in 3.5 wt.% sodium chloride solutions at 25°C were performed. The effects of the electrochemical properties under the stress corrosion with low strain rates were investigated. The microstructures of cross section were observed by optical microscope. The results showed that the ultimate tensile strengths of Mg-Zn-In-Sn alloy increased and the strain decreased as the strain rates increased. Open circuit potentials (OCP) of Mg-Zn-In-Sn alloy electrode possess stability and the loop currents (LC) were improved with the increasing of stress in the elastic zone. The variation of OCP and LC did not change with the increasing of strain-rate. The microstructure of cross section observing revealed the mechanism of OCP and LC changing. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  1. Investigation of the corrosion resistance of Ti-13Nb-13Zr alloy by electrochemical techniques and surface analysis

    International Nuclear Information System (INIS)

    Assis, Sergio Luiz de

    2006-01-01

    In this work, the in vitro corrosion resistance of the Ti-13Nb-13Zr alloy, manufactured at a national laboratory, and used for orthopedic applications, has been investigated in solutions that simulate the body fluids. The electrolytes used were 0.9 % (mass) NaCl, Hanks' solution, a culture medium (MEM), and the two last electrolytes, without and with addition of hydrogen peroxide. The aim of peroxide addition was to simulate the conditions found when inflammatory reactions occur due to surgical procedures. The corrosion resistance of alloys commercially in use as biomaterials, Ti-6Al-7Nb and Ti-6Al-4V, as well as of the pure titanium (Ti-cp), was also studied for comparison with the Ti-13Nb-13Zr alloy. The corrosion resistance characterization was carried out by electrochemical and surface analysis techniques. The electrochemical tests used were: open circuit potential measurements as a function of tim; potentiodynamic polarization; and electrochemical impedance spectroscopy (EIE). The impedance experimental diagrams were interpreted using equivalent electric circuits that simulate an oxide film with a duplex structure composed of an internal and compact, barrier type layer, and an external porous layer. The results showed that the corrosion resistance is due mainly to the barrier type layer. The titanium alloys and the Ti-cp showed high corrosion resistance in all electrolytes used. The oxides formed on the Ti-13Nb-13Zr, either naturally or during immersion in MEM ar Hank's solution was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (MEV). The results showed that the presence of hydrogen peroxide in MEM promotes the growth of the porous layer and incorporation of mineral ions, besides favouring hydroxyapatite formation. The cytotoxicity of the Ti-13Nb-13Zr alloy was also evaluated and it was shown to be non-toxic. (author)

  2. Corrosion Behaviour of a New Low-Nickel Stainless Steel Reinforcement: A Study in Simulated Pore Solutions and in Fly Ash Mortars

    Directory of Open Access Journals (Sweden)

    M. Criado

    2012-01-01

    Full Text Available The present paper studies the corrosion behaviour of a new lower-cost type of austenitic stainless steel (SS with a low nickel content in alkaline-saturated calcium hydroxide solution (a simulated concrete pore (SCP solution with sodium chloride (0.0%, 0.4%, 1.0%, 2.0%, 3.0%, and 5.0% NaCl and embedded in alkali-activated fly ash (AAFA mortars manufactured using two alkaline solutions, with and without chloride additions (2% and 5%, in an environment of constant 95% relative humidity. Measurements were performed at early age curing up to 180 days of experimentation. The evolution with time of electrochemical impedance spectroscopy was studied. Rct values obtained in SCP solution or in fly ash mortars were so high that low-nickel SS preserved its passivity, exhibiting high corrosion resistance

  3. Erosion–corrosion behaviour of Ni-based superalloy Superni-75 in ...

    Indian Academy of Sciences (India)

    Erosion–corrosion behaviour of Ni-based superalloy. Superni-75 in the real service environment of the boiler. T S SIDHU. 1,∗. , S PRAKASH. 2. , R D AGRAWAL. 2 and. RAMESH BHAGAT. 1. 1Shaheed Bhagat Singh College of Engineering and Technology,. Ferozepur 152 004. 2Indian Institute of Technology Roorkee, ...

  4. Thermal characteristics and corrosion behaviour of Mg–xZn alloys ...

    Indian Academy of Sciences (India)

    The thermal parameters of Mg–Zn cast alloys with 0.5–9 wt% Zn were evaluated by using computer aided cooling curve thermal analysis (CA–CCTA), whereas the corrosion behaviour was investigated by potentiodynamic polarization and immersion tests. Thermal analysis results revealed that the dendrite coherency ...

  5. Thermal characteristics and corrosion behaviour of Mg–xZn alloys ...

    Indian Academy of Sciences (India)

    The thermal parameters of Mg–xZn cast alloys with 0·5–9 wt% Zn were evaluated by using computer aided cooling curve thermal analysis (CA–CCTA), whereas the corrosion behaviour was investigated by potentiody- namic polarization and immersion tests. Thermal analysis results revealed that the dendrite coherency ...

  6. Erosion–corrosion behaviour of Ni-based superalloy Superni-75 in ...

    Indian Academy of Sciences (India)

    corrosion behaviour of Ni-based superalloy Superni-75 in the actual service environment of the coal- fired boiler of a thermal power plant at 900. ◦. C under cyclic conditions. This alloy is developed by Mishra Dhatu Nigam Limited, Hyderabad ...

  7. Erosion–corrosion behaviour of Ni-based superalloy Superni-75

    Indian Academy of Sciences (India)

    The aim of the present investigation is to evaluate the erosion–corrosion behaviour of Ni-based superalloy Superni-75 in the real service environment of the coal-fired boiler of a thermal power plant. The cyclic experimental study was performed for 1000 h in the platen superheater zone of the coal-fired boiler where the ...

  8. Corrosion Behaviour of Steels in Nigerian Food Processing ...

    African Journals Online (AJOL)

    Michael Horsfall

    also in terms of the (specific metal loss per unit time in mg/cm2/day) (Fig.3) to indicate the quantity of metal getting into the food (or whatever product) per unit area of the metal exposed per unit time. This has the benefit that with a knowledge of the chemical composition of the metal or alloy and assuming a uniform corrosion ...

  9. Corrosion behaviour and surface analysis of a Co-Cr and two Ni-Cr dental alloys before and after simulated porcelain firing.

    Science.gov (United States)

    Qiu, Jing; Yu, Wei-Qiang; Zhang, Fu-Qiang; Smales, Roger J; Zhang, Yi-Lin; Lu, Chun-Hui

    2011-02-01

    This study evaluated the corrosion behaviour and surface properties of a commercial cobalt-chromium (Co-Cr) alloy and two nickel-chromium (Ni-Cr) alloys [beryllium (Be)-free and Be-containing] before and after a simulated porcelain-firing process. Before porcelain firing, the microstructure, surface composition and hardness, electrochemical corrosion properties, and metal-ion release of as-cast alloy specimens were examined. After firing, similar alloy specimens were examined for the same properties. In both as-cast and fired conditions, the Co-Cr alloy (Wirobond C) showed significantly more resistance to corrosion than the two Ni-Cr alloys. After firing, the corrosion rate of the Be-free Ni-Cr alloy (Stellite N9) increased significantly, which corresponded to a reduction in the levels of Cr, molybdenum (Mo), and Ni in the surface oxides and to a reduction in the thickness of the surface oxide film. The corrosion properties of the Co-Cr alloy and the Be-containing Ni-Cr alloy (ChangPing) were not significantly affected by the firing process. Porcelain firing also changed the microstructure and microhardness values of the alloys, and there were increases in the release of Co and Ni ions, especially for Ni from the Be-free Ni-Cr alloy. Thus, the corrosion rate of the Be-free Ni-Cr alloy increased significantly after porcelain firing, whereas the firing process had little effect on the corrosion susceptibility of the Co-Cr alloy and the Be-containing Ni-Cr alloy. © 2011 Eur J Oral Sci.

  10. The electrochemical behaviour of copper in aerated 1 mol·dm-3 NaCl at room temperature: Pt. 2

    International Nuclear Information System (INIS)

    King, F.; Litke, C.D.

    1989-05-01

    Uniform corrosion will be an important process in determining the lifetime of a copper nuclear fuel waste container. We need to know the mechanism of the corrosion reaction if we are to make reliable predictions about the long-term corrosion behaviour. This series of reports summarizes the results of an electrochemical investigation of the corrosion of copper in aerated 1 mol·dm -3 NaCl at room temperature. In part 2 we discuss the cathodic reduction of oxygen on a copper rotating disc electrode. The anodic dissolution of copper and the behaviour under freely corroding conditions are considered in Parts 1 and 3, respectively. The mechanism of the oxygen reduction reaction has been studied over a wide range of applied potentials. At potentials close to the corrosion potential, the mechanism is complicated and not fully understood. It is possible that in this potential region, oxygen is reduced to peroxide. At more negative applied potentials, between -0.50 and -0.90 V sce , the predominant process is the 4-electron reduction of oxygen to hydroxide. In this potential region, the rate is controlled jointly by the interfacial reaction and the rate of supply of oxygen to the electrode surface. At an applied potential of about -1.0 V sce , the rate of reduction is almost totally controlled by the rate of transport of oxygen. Values for the kinetic parameters for the 4-electron reaction have been determined. In addition, the diffusion coefficient of oxygen was found to be 1.7 3 ± 0.0 5 x 10 -5 cm 2 ·s -1 . These data, along with the results on the anodic dissolution of copper, will be used to explain the behaviour of copper under freely corroding conditions

  11. Surface modification and electrochemical behaviour of undoped nanodiamonds

    International Nuclear Information System (INIS)

    Zang Jianbing; Wang Yanhui; Bian Linyan; Zhang Jinhui; Meng Fanwei; Zhao Yuling; Ren Shubin; Qu Xuanhui

    2012-01-01

    Surface modifications of undoped nanodiamond (ND) particles were carried out through different annealing treatments. The methods of Fourier transform infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy were used to characterize the ND surface before and after the annealing process. The electrochemical properties of the modified ND powders in aqueous solution were investigated with Fe(CN) 6 3−/4− as a redox probe. When the annealing temperature was below 850 °C, vacuum annealing removed parts of the oxygen-containing surface functionalities from the ND surface and produced more sp 2 carbon atoms in the shell. The charge transfer of the Fe(CN) 6 3−/4− redox couple decreased with increasing annealing temperature. Re-annealing in air restored the original surface conditions: few sp 2 -bonded carbon atoms and similar surface functionalities, and thus the electrochemical activity. When ND was annealed in vacuum at 900–1100 °C, more serious graphitization produced a continuous fullerenic shell wrapped around a diamond core, which had a high conductivity and electrochemical activity. This provides a novel nanoparticle with high conductivity and high stability for electrochemical applications.

  12. Effect of Welding Process on Microstructure, Mechanical and Pitting Corrosion Behaviour of 2205 Duplex Stainless Steel Welds

    Science.gov (United States)

    Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

    2018-03-01

    An attempt has been made to weld 2205 Duplex stainless steel of 6mm thick plate using conventional gas tungsten arc welding (GTAW) and activated gas tungsten arc welding (A- GTAW) process using silica powder as activated flux. Present work is aimed at studying the effect of welding process on depth of penetration, width of weld zone of 2205 duplex stainless steel. It also aims to observe the microstructural changes and its effect on mechanical properties and pitting corrosion resistance of 2205 duplex stainless steel welds. Metallography is done to observe the microstructural changes of the welds using image analyzer attached to the optical microscopy. Hardness studies, tensile and ductility bend tests were evaluated for mechanical properties. Potentio-dynamic polarization studies were carried out using a basic GillAC electro-chemical system in 3.5% NaCl solution to observe the pitting corrosion behaviour. Results of the present investigation established that increased depth of penetration and reduction of weld width in a single pass by activated GTAW with the application of SiO2 flux was observed when compared with conventional GTAW process. It may be attributed to the arc constriction effect. Microstructure of the weld zones for both the welds is observed to be having combination of austenite and delta ferrite. Grain boundary austenite (GBA) with Widmanstatten-type austenite (WA) of plate-like feature was nucleated from the grain boundaries in the weld zone of A-GTAW process. Mechanical properties are relatively low in activated GTAW process and are attributed to changes in microstructural morphology of austenite. Improved pitting corrosion resistance was observed for the welds made with A-GTAW process.

  13. Boron-doped Diamond Electrodes: Electrochemical, Atomic Force Microscopy and Raman Study towards Corrosion-modifications at Nanoscale

    International Nuclear Information System (INIS)

    Kavan, Ladislav; Vlckova Zivcova, Zuzana; Petrak, Vaclav; Frank, Otakar; Janda, Pavel; Tarabkova, Hana; Nesladek, Milos; Mortet, Vincent

    2015-01-01

    Highlights: • B-doped diamond is nanostructured by corrosion-driven modifications occurring at carbonaceous impurity sites (sp 2 -carbons). • The electrochemical oxidation partly transforms a hydrogen-terminated diamond surface to O-terminated one, but the electrocatalytic activity of plasmatically O-terminated diamond is not achieved. • In contrast to all usual sp 2 carbons, the Raman spectra of B-doped diamond electrodes do not change upon electrochemical charging/discharging. - Abstract: Comparative studies of boron-doped diamonds electrodes (polycrystalline, single-crystalline, H-/O-terminated, and with different sp 3 /sp 2 ratios) indicate morphological modifications of diamond which are initiated by corrosion at nanoscale. In-situ electrochemical AFM imaging evidences that the textural changes start at non-diamond carbonaceous impurity sites treated at high positive potentials (>2.2 V vs. Ag/AgCl). The primary perturbations subsequently develop into sub-micron-sized craters. Raman spectroscopy shows that the primary erosion site is graphite-like (sp 2 -carbon), which is preferentially removed by anodic oxidation. Other non-diamond impurity, viz. tetrahedral amorphous carbon (t-aC), is less sensitive to oxidative decomposition. The diamond-related Raman features, including the B-doping-assigned modes, are intact during reversible electrochemical charging/discharging, which is a salient difference from all usual sp 2 -carbons. The electrochemical oxidation partly transforms a hydrogen-terminated diamond surface to O-terminated one, but the electrocatalytic activity of plasmatically O-terminated diamond is not achieved for a model redox couple, Fe 3+/2+ . Electrochemical impedance spectra were fitted to six different equivalent circuits. The determination of acceptor concentrations is feasible even for highly-doped diamond electrodes.

  14. A state of the art on electrochemical noise technique. Assessment of corrosion characteristics and development of remedial technology in nuclear materials

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Jin; Kim, Joung Soo; Kim, Hong Pyo; Lim, Yun Soo; Yi, Yong Sun; Chung, Man Kyo

    2003-02-01

    The studies for the application of electrochemical noise technique were reviewed in terms of principle, analysing method and application examples of this technique. Because 4% of the economic damage of industry is caused by metallic corrosion, it is important to find and protect corrosive materials and location. By corrosion monitoring of industrial facilities such as nuclear power plant using Electrochemical Noise Measurement(ENM), corrosion attack can be detected and furthermore it can be indicated whether the attacked materials is replaced by new one or not. According to development of control and electronic technology, it was easy to apply ENM to the industry and the interest in ENM also increased. As corrosion is produced on a metal under corrosive environment, local anode(oxidation) and cathode(reduction) are formed. Hence, there is potential difference and current flow between the anode and cathode. ENM is monitoring the potential difference and the current flow with time by high impedance load voltmeter and Zero Resistance Ammeter(ZRA), respectively. The potential difference and current flow generated spontaneously without any application of current and potential between electrodes are monitored by electrochemical noise technique, Thereby ENM can be regarded as the most ideal corrosion monitoring method for the industrial facility and nuclear power plant having corrosion damage and difficulty in access of human body. Moreover, it is possible to obtain the spontaneous and reliable results from the metals damaged by ununiform and localized corrosion such as pitting and SCC using ENM while it is difficult to obtain the reliable result using traditional linear polarization and ac-impedance measurement. In many countries, there are extensive works concerned with application of electrochemical noise technique to corrosion monitoring of nuclear power plant and other industrial facilities, whereas there is little work on this field in Korea. Systematic study for

  15. The corrosion protection mechanism of rust converters: An electrochemical impedance spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Collazo, A. [ENCOMAT Group, ETSEI, Universidade de Vigo, Campus Universitario, 36310 Vigo (Spain); Novoa, X.R., E-mail: rnovoa@uvigo.e [ENCOMAT Group, ETSEI, Universidade de Vigo, Campus Universitario, 36310 Vigo (Spain); Perez, C.; Puga, B. [ENCOMAT Group, ETSEI, Universidade de Vigo, Campus Universitario, 36310 Vigo (Spain)

    2010-08-30

    Oxide converters represent an interesting alternative for the protection of steel surfaces that have some degree of rust. Although the mechanism of these converters is not clear, it is assumed that they react with iron oxides and generate new compounds that may have a passivation effect on the steel surface. This last point is not well established, and several authors have even spoken of an accelerating effect of these compounds. We present here a study of the electrochemical behaviour of iron oxides immersed in the rust converter. The modulus of the impedance increases significantly after a certain time of immersion, suggesting that the electronic conductivity and, consequently, the rate of the cathodic reaction tend to decrease.

  16. Corrosion behaviour of Arc-PVD coatings and hybrid systems

    International Nuclear Information System (INIS)

    Reichel, K.

    1992-01-01

    To achieve a comprehensive protective effect against corrosion and wear stresses, coating systems are increasingly being developed, in which there is a separation of the tasks of the coating materials regarding the protective effect. On the one hand, pure PVD coating systems are used, on the other hand hybrid coatings are examined, where galvanic processes are combined with PVD technique. The results of experiments introduced in this article were determined on Arc-PVD coatings. By this process, titanium nitride and chromium nitride coatings are both deposited directly on the basic material and are also deposited as combination coatings of Ti/TiN and chemical nickel/TiN. (orig.) [de

  17. Effect of prior corrosion state on the fatigue small cracking behaviour of 6151-T6 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li Xudong [Department of Engineering Mechanics, AML, Tsinghua University, Beijing 100084 (China); Naval Aeronautical Engineering Academy Qingdao Branch, Qingdao 266000 (China); Wang Xishu, E-mail: xshwang@tsinghua.edu.cn [Department of Engineering Mechanics, AML, Tsinghua University, Beijing 100084 (China); Ren Huaihui; Chen Yinlong [Department of Engineering Mechanics, AML, Tsinghua University, Beijing 100084 (China); Mu Zhitao [Naval Aeronautical Engineering Academy Qingdao Branch, Qingdao 266000 (China)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Relationship of corrosion pit and fatigue crack is established based on SEM. Black-Right-Pointing-Pointer An equivalent relationship between accelerated and natural corrosion is build up. Black-Right-Pointing-Pointer Prior corrosion damage is crucial to the subsequent fatigue cracking behaviour. Black-Right-Pointing-Pointer The prior corrosion fatigue crack growth rate is expressed by the term of k{sigma}{sub max}{sup n}a. Black-Right-Pointing-Pointer Corrosion states such as SC15, are defined based on corrosion spectrum. - Abstract: The purpose of this paper was to estimate the reliable effect of prior corrosion state on fatigue micro crack initiation and early stage propagation behaviour of aluminum alloy based on scanning electron microscopy (SEM) in situ observation. Results indicated that multi-cracks initiation occurred almost at the corrosion pits and the early stage of fatigue micro crack propagation behaviour can be described by K{sub I}/K{sub II}-mixed mode. The importance of crack-face interaction via crack-face corrosion pits interlocking/bridging was emphasised in the mixed mode. The fatigue crack growth rate in the corrosion states can be empirically expressed by the term of k{sigma}{sub max}{sup n}a.

  18. Effect of prior corrosion state on the fatigue small cracking behaviour of 6151-T6 aluminum alloy

    International Nuclear Information System (INIS)

    Li Xudong; Wang Xishu; Ren Huaihui; Chen Yinlong; Mu Zhitao

    2012-01-01

    Highlights: ► Relationship of corrosion pit and fatigue crack is established based on SEM. ► An equivalent relationship between accelerated and natural corrosion is build up. ► Prior corrosion damage is crucial to the subsequent fatigue cracking behaviour. ► The prior corrosion fatigue crack growth rate is expressed by the term of kσ max n a. ► Corrosion states such as SC15, are defined based on corrosion spectrum. - Abstract: The purpose of this paper was to estimate the reliable effect of prior corrosion state on fatigue micro crack initiation and early stage propagation behaviour of aluminum alloy based on scanning electron microscopy (SEM) in situ observation. Results indicated that multi-cracks initiation occurred almost at the corrosion pits and the early stage of fatigue micro crack propagation behaviour can be described by K I /K II -mixed mode. The importance of crack-face interaction via crack-face corrosion pits interlocking/bridging was emphasised in the mixed mode. The fatigue crack growth rate in the corrosion states can be empirically expressed by the term of kσ max n a.

  19. Electrochemical behaviour of laser-clad Ti6Al4V with CP Ti in 0.1 M oxalic acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Obadele, Babatunde Abiodun, E-mail: obadele4@gmail.com [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Olubambi, Peter A. [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Andrews, Anthony [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Materials Engineering, Kwame Nkrumah University of Science and Technology, Kumasi (Ghana); Pityana, Sisa [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); National Laser Center, Council for Scientific and Industrial Research, Pretoria (South Africa); Mathew, Mathew T. [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612 (United States)

    2015-10-15

    The relationship between the microstructure and corrosion behaviour of Ti6Al4V alloy and laser-clad commercially pure (CP) Ti coating was investigated. The microstructure, phases and properties of the clad layers were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Electrochemical measurement techniques including open circuit potential (OCP) and potentiodynamic polarisation were used to evaluate the corrosion behaviour of Ti6Al4V alloy in 0.1 M oxalic acid solution and the results compared to the behaviour of laser-clad CP Ti at varying laser scan speed. Results showed that laser-clad CP Ti at scan speed of 0.4 m/min formed a good cladding layer without defects such as cracks and pores. The phase present in the cladding layer was mostly α′-Ti. The microstructures of the clad layer were needle like acicular/widmanstätten α. An improvement in the microhardness values was also recorded. Although the corrosion potentials of the laser-clad samples were less noble than Ti6Al4V alloy, the polarisation measurement showed that the anodic current density was lower and also increases with increasing laser scanning speed. - Highlights: • The microstructure and corrosion behaviour of laser-clad CP Ti was investigated. • Laser-clad CP Ti 0.4 m/min scan speed gave a good coating without cracks and pores. • The phase present in the clad layer was mostly α′-Ti. • An improvement in the microhardness values was also recorded. • Anodic current density for coatings increases with increasing laser scan speed.

  20. Susceptibility of 17-4PH stainless steel to stress corrosion cracking in aqueous environments by electrochemical techniques

    International Nuclear Information System (INIS)

    Diaz S, A.C.

    1997-01-01

    The susceptibility of a 17-4PH type steel to Stress Corrosion Cracking (SCC) in low pressure steam turbine environments was assessed using slow strain rate test at 90 Centigrade and at 1.35x10 -6 seg -1 . Environments tested included different concentrated solutions of NaCl, NaOH and Na 2 SO 4 . It was concluded that this steel is susceptible to SCC in 20 % NaCl and pH=3 and in 20 % NaCl pH=neutral but under cathodic polarisation. The electrochemical potential noise of the specimen was monitored during the test. The naturally fluctuations in potential were arise due to spontaneous brake protective film and were characteristics of the kind of corrosion like pit or stress corrosion cracking. After that using Fast Fourier Transformer (FFT) the noise data set were analyzed to obtain power spectral density plots which showed differences between general corrosion and localized corrosion. Polarization curves were carry out at two different rates and them showed the general behavior of the systems. (Author)

  1. An electrochemical investigation of the corrosion behavior of Al-Si-Cu hypereutectic alloys in alcoholic environments

    International Nuclear Information System (INIS)

    Traldi, S. M.; Rossi, J. L.; Costa, I.

    2003-01-01

    Al-Si-Cu hypereutectic alloys produced by spray forming are mostly used in the automotive industry, especially for cylinder liners. they the advantage of low weight associated with low coefficient of thermal expansion and excellent mechanical properties- mainly wear resistance at high temperatures. The corrosion s resistance of these alloys in fuels, particularly alcoholic media, however is not yet known. In this investigation, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation hove been used to evaluate the corrosion resistance of a hyper eutectic Al-Si-Cu alloy in alcoholic environments. the EIS tests carried out in pure ethanol, and ethanol with small additions (1 mM) of acid an chloride to investigate the effect of these contaminants on corrosion resistance. The corrosion resistance of a grey cast iron has also been evaluated in pure ethanol for comparison. The Al-Si-Cu alloy showed high corrosion resistance in pure ethanol, far superior to that of grey cast iron in the same medium. (Author) 13 refs

  2. Effects of alpha-decay on spent fuel corrosion behaviour

    International Nuclear Information System (INIS)

    Wiss, T.; Rondinella, V.V.; Cobos, J.; Wegen, D.H.; Amme, M.; Ronchi, C.

    2004-01-01

    An overview of results in the area of spent fuel characterization as nuclear waste is presented. These studies are focused on primary aspects of spent fuel corrosion, by considering different fuel compositions and burn ups, as well as a wide set of environmental conditions. The key parameter is the storage time of the fuel e.g. in view of spent fuel retrieval or in view of its final disposal. To extrapolate data obtainable from a laboratory-acceptable timescale to those expected after storage periods of interest have elapsed (amounting in the extreme case to geological ages) is a tough challenge. Emphasis is put on key aspects of fuel corrosion related to fuel properties at a given age and environmental conditions expected in the repository: e.g. the fuel activity (radiolysis effects), the effects of helium build-up and of groundwater composition. A wide range of techniques, from traditional leaching experiments to advanced electrochemistry, and of materials, including spent fuel with different compositions/burnups and analogues like the so-called alpha-doped UO 2 , are employed for these studies. The results confirm the safety of European underground repository concepts. (authors)

  3. Microstructure and corrosion behaviour of pulsed plasma-nitrided AISI H13 tool steel

    International Nuclear Information System (INIS)

    Basso, Rodrigo L.O.; Pastore, Heloise O.; Schmidt, Vanessa; Baumvol, Israel J.R.; Abarca, Silvia A.C.; Souza, Fernando S. de; Spinelli, Almir; Figueroa, Carlos A.; Giacomelli, Cristiano

    2010-01-01

    The effect of pulsed plasma nitriding temperature and time on the pitting corrosion behaviour of AISI H13 tool steel in 0.9% NaCl solutions was investigated by cyclic polarization. The pitting potential (E pit ) was found to be dependent on the composition, microstructure and morphology of the surface layers, whose properties were determined by X-ray diffraction and scanning electron microscopy techniques. The best corrosion protection was observed for samples nitrided at 480 o C and 520 o C. Under such experimental conditions the E pit -values shifted up to 1.25 V in the positive direction.

  4. Structural, electrical and electrochemical behaviours of LiNi0⋅4M0 ...

    Indian Academy of Sciences (India)

    Administrator

    Structural, electrical and electrochemical behaviours of. LiNi0⋅4M0⋅1Mn1⋅5O4 (M = Al, Bi) as cathode material for Li-ion batteries. G P NAYAKA, J MANJANNA*, K C ANJANEYA, P MANIKANDAN†, P PERIASAMY† and. V S TRIPATHI††. Department of Industrial Chemistry, Kuvempu University, Shankaraghatta 577 451, ...

  5. Porphyrins as Corrosion Inhibitors for N80 Steel in 3.5% NaCl Solution: Electrochemical, Quantum Chemical, QSAR and Monte Carlo Simulations Studies

    Directory of Open Access Journals (Sweden)

    Ambrish Singh

    2015-08-01

    Full Text Available The inhibition of the corrosion of N80 steel in 3.5 wt. % NaCl solution saturated with CO2 by four porphyrins, namely 5,10,15,20-tetrakis(4-hydroxyphenyl-21H,23H-porphyrin (HPTB, 5,10,15,20-tetra(4-pyridyl-21H,23H-porphyrin (T4PP, 4,4′,4″,4‴-(porphyrin-5,10,15,20-tetrayltetrakis(benzoic acid (THP and 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP was studied using electrochemical impedance spectroscopy (EIS, potentiodynamic polarization, scanning electrochemical microscopy (SECM and scanning electron microscopy (SEM techniques. The results showed that the inhibition efficiency, η% increases with increasing concentration of the inhibitors. The EIS results revealed that the N80 steel surface with adsorbed porphyrins exhibited non-ideal capacitive behaviour with reduced charge transfer activity. Potentiodynamic polarization measurements indicated that the studied porphyrins acted as mixed type inhibitors. The SECM results confirmed the adsorption of the porphyrins on N80 steel thereby forming a relatively insulated surface. The SEM also confirmed the formation of protective films of the porphyrins on N80 steel surface thereby protecting the surface from direct acid attack. Quantum chemical calculations, quantitative structure activity relationship (QSAR were also carried out on the studied porphyrins and the results showed that the corrosion inhibition performances of the porphyrins could be related to their EHOMO, ELUMO, ω, and μ values. Monte Carlo simulation studies showed that THP has the highest adsorption energy, while T4PP has the least adsorption energy in agreement with the values of σ from quantum chemical calculations.

  6. Porphyrins as Corrosion Inhibitors for N80 Steel in 3.5% NaCl Solution: Electrochemical, Quantum Chemical, QSAR and Monte Carlo Simulations Studies.

    Science.gov (United States)

    Singh, Ambrish; Lin, Yuanhua; Quraishi, Mumtaz A; Olasunkanmi, Lukman O; Fayemi, Omolola E; Sasikumar, Yesudass; Ramaganthan, Baskar; Bahadur, Indra; Obot, Ime B; Adekunle, Abolanle S; Kabanda, Mwadham M; Ebenso, Eno E

    2015-08-18

    The inhibition of the corrosion of N80 steel in 3.5 wt. % NaCl solution saturated with CO2 by four porphyrins, namely 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphyrin (HPTB), 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphyrin (T4PP), 4,4',4″,4‴-(porphyrin-5,10,15,20-tetrayl)tetrakis(benzoic acid) (THP) and 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP) was studied using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM) techniques. The results showed that the inhibition efficiency, η% increases with increasing concentration of the inhibitors. The EIS results revealed that the N80 steel surface with adsorbed porphyrins exhibited non-ideal capacitive behaviour with reduced charge transfer activity. Potentiodynamic polarization measurements indicated that the studied porphyrins acted as mixed type inhibitors. The SECM results confirmed the adsorption of the porphyrins on N80 steel thereby forming a relatively insulated surface. The SEM also confirmed the formation of protective films of the porphyrins on N80 steel surface thereby protecting the surface from direct acid attack. Quantum chemical calculations, quantitative structure activity relationship (QSAR) were also carried out on the studied porphyrins and the results showed that the corrosion inhibition performances of the porphyrins could be related to their EHOMO, ELUMO, ω, and μ values. Monte Carlo simulation studies showed that THP has the highest adsorption energy, while T4PP has the least adsorption energy in agreement with the values of σ from quantum chemical calculations.

  7. Impact of Desulfovibrio alaskensis biofilms on corrosion behaviour of carbon steel in marine environment.

    Science.gov (United States)

    Wikieł, Agata J; Datsenko, Iaryna; Vera, Mario; Sand, Wolfgang

    2014-06-01

    Sulfate reducing prokaryotes are associated with the steel deterioration. They build heterogeneous biofilms, capable of accelerating corrosion processes. In this study metabolic activity and the biofilm development of Desulfovibrio alaskensis were correlated to electrochemical response of carbon steel surface. In the exponential growth phase sulfide concentration reached its maximum of about 10mM. This phenomenon was responsible for the parallel increase in the corrosion potential (Ecorr) up to -720mV (vs. SCE). Subsequently, during the intensive biofilm formation and development another Ecorr peak (-710mV vs. SCE) occurred. Decrease in Ecorr was registered during the biofilm maturation and kept stable, being 20mV lower than in the control. While carbon steel was protected from the microbial attachment and exposed to metabolic products, only one potential maximum (-730mV vs. SCE) was recorded. Here Ecorr variations coincided with sulfide concentration changes and kept at 120mV lower vs. the control. Weight loss examinations revealed corrosion rates, which did not exceed 0.05mm/y. Confocal microscopy suggested the importance of extracellular proteins in the biofilm formation. Above 150 proteins were detected in the EPS matrix. Surface effects of biofilm and metabolic products were visualised, revealing the role of attached microorganisms in the localised corrosion. © 2013.

  8. A fundamental understanding of the electrochemical noise related to pitting corrosion of carbon steel

    Science.gov (United States)

    Cheng, Yufeng

    The pitting behavior of carbon steel in chloride-containing solutions was studied by the electrochemical noise technique. The semiconducting nature of the passive film formed on carbon steel was revealed as well. The initiation of metastable pits is generally indicated by a typical current and potential transient with the shape of a quick current rise and potential drop followed by a slow recovery. The potential fluctuations mainly come from the response of the electrode capacitance to pit growth charge. Only the current transients directly reflect the metastable pitting process. The potential dependence of the pit initiation rate is well illustrated by the point defect model, which assumes that pitting initiation is due to the anion-catalyzed cation vacancy condensation at the film/metal interface. Pit growth kinetics are controlled by the ohmic potential drop across the cover over the pits. The repassivation time of metastable pits is affected by the potential drop across the pit cover. A pit stabilization criterion of the ratio of peak pit current to pit radius indicates that the critical condition to maintain the stable pit growth must exceed 2 x 10-2 A cm-1 to avoid repassivation. The main role of chloride ions in pitting is to increase the chance of the breakdown of a passive film, rather than to inhibit surface repassivation. The initiation of a metastable pit will have a certain influence on subsequent pitting events in the case of high pitting activity. When the pitting activity decreases, the metastable pitting events will follow the Poisson distribution. Spectral analysis of noise data indicates that any transient having a sudden birth or a sudden death generates f-2 noise, while that without sudden change shows f -4 behavior. The roll-off frequency reflects the repassivation or growth rate of metastable pits. The noise resistance coincides with the polarization resistance only in passivity or general corrosion. For pitting, the noise resistance cannot

  9. Electrochemical and DFT studies of quinoline derivatives on corrosion inhibition of AA5052 aluminium alloy in NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dapeng; Yang, Dong [Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, School of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Zhang, Daquan, E-mail: zhangdaquan@shiep.edu.cn [Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, School of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Li, Kang; Gao, Lixin [Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, School of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Lin, Tong [Institute for Frontier Materials, Deakin University, Geelong, VIC 3216 (Australia)

    2015-12-01

    Graphical abstract: - Highlights: • 8-AQ and 8-NQ have a good anti-corrosion effect acting as anodic inhibitor. • The inhibition mechanism is dominated by geometric covering effect. • The p-orbital of reactive site of inhibitor and sp-orbital of Al are hybridizing. - Abstract: Two quinoline derivatives, 8-aminoquinoline (8-AQ) and 8-nitroquinoline (8-NQ), have been used as inhibitors to examine their corrosion protection effect on AA5052 aluminium alloy in 3% NaCl solution. The weight-loss and electrochemical measurement have indicated that 8-AQ and 8-NQ play as anodic inhibitor to retard the anodic electrochemical process. SEM/EDS analysis clearly shows that 8-AQ and 8-NQ form a protective film on the AA5052 alloy surface. Density functional theory (DFT) calculation confirmed the formation of strong hybridization between the p-orbital of reactive sites in the inhibitor molecules and the sp-orbital of the Al atom. 8-aminoquinoline and 8-nitroquinoline may be useful as effective corrosion inhibitors for aluminium alloys.

  10. Influence of Silver nanoparticles addition on the phase transformation, mechanical properties and corrosion behaviour of Cu–Al–Ni shape memory alloys

    International Nuclear Information System (INIS)

    Saud, Safaa N.; Hamzah, E.; Abubakar, T.; Bakhsheshi-Rad, H.R.; Farahany, S.; Abdolahi, A.; Taheri, M.M.

    2014-01-01

    Highlights: • Thermal analysis showed four different phase β, α, NiAl and γ2 during solidification. • The martensite appeared in the microstructure as a plate and needle like shape. • Shape recovery ratio of 80% was obtained after Ag nanoparticles addition. • Effect of Ag nanoparticles on the corrosion behaviour of Cu–Al–Ni SMA was investigated. - Abstract: Incorporation of silver nanoparticles into Cu-based shape memory alloys is recommended to enhance their phase transformation behaviour. However, this incorporation can affect their transformation temperatures, mechanical, microstructural and corrosion characteristics. Four different phase reactions β, α, NiAl and γ 2 were detected on a derivative curve during the solidification by-computer-aided cooling curve thermal analysis. The highest fraction solid (82%) was calculated for the parent phase (β) based on the Newtonian baseline method. The microstructural changes and mechanical properties were investigated using field emission scanning electron microscopy, X-ray diffraction tensile test and shape memory effect test. It was found that the addition of Ag can control the phase morphology and orientations along with the formation of the Ag-rich precipitates, and thus the tensile strength, elongation, fracture stress–strain, yield strength and shape memory effect are improved. Remarkably, the shape recovery ratio reached approximately 80% of the original shape. The corrosion behaviour of the Cu–Al–Ni shape memory alloy were investigated using electrochemical tests in NaCl solution and their results showed that the corrosion potential (E corr ) of Cu–Al–Ni SMA is shifted towards the nobler direction from −307.4 to −277.1 m V SCE with the addition of 0.25 wt.% Ag

  11. Influence of Silver nanoparticles addition on the phase transformation, mechanical properties and corrosion behaviour of Cu–Al–Ni shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Saud, Safaa N.; Hamzah, E., E-mail: esah@fkm.utm.my; Abubakar, T.; Bakhsheshi-Rad, H.R.; Farahany, S.; Abdolahi, A.; Taheri, M.M.

    2014-11-05

    Highlights: • Thermal analysis showed four different phase β, α, NiAl and γ2 during solidification. • The martensite appeared in the microstructure as a plate and needle like shape. • Shape recovery ratio of 80% was obtained after Ag nanoparticles addition. • Effect of Ag nanoparticles on the corrosion behaviour of Cu–Al–Ni SMA was investigated. - Abstract: Incorporation of silver nanoparticles into Cu-based shape memory alloys is recommended to enhance their phase transformation behaviour. However, this incorporation can affect their transformation temperatures, mechanical, microstructural and corrosion characteristics. Four different phase reactions β, α, NiAl and γ{sub 2} were detected on a derivative curve during the solidification by-computer-aided cooling curve thermal analysis. The highest fraction solid (82%) was calculated for the parent phase (β) based on the Newtonian baseline method. The microstructural changes and mechanical properties were investigated using field emission scanning electron microscopy, X-ray diffraction tensile test and shape memory effect test. It was found that the addition of Ag can control the phase morphology and orientations along with the formation of the Ag-rich precipitates, and thus the tensile strength, elongation, fracture stress–strain, yield strength and shape memory effect are improved. Remarkably, the shape recovery ratio reached approximately 80% of the original shape. The corrosion behaviour of the Cu–Al–Ni shape memory alloy were investigated using electrochemical tests in NaCl solution and their results showed that the corrosion potential (E{sub corr}) of Cu–Al–Ni SMA is shifted towards the nobler direction from −307.4 to −277.1 m V{sub SCE} with the addition of 0.25 wt.% Ag.

  12. Influence of aging at 180C on the corrosion behaviour of a ternary Al-Li-Zr alloy

    DEFF Research Database (Denmark)

    Ambat, Rajan; Prasad, R.K.; Dwarakadasa, E.S.

    1994-01-01

    The influence of aging at 180 °C on the corrosion behaviour of an Al-1.5%Li-0.1%Zr alloy has been studied using weight loss, open circuit potential (OCP) measurements and potentiodynamic polarization measurements in 3.5% NaCl solution. Corrosion rates obtained from weight loss and Icorr values...

  13. The effect of welding parameters on the corrosion behaviour of friction stir welded AA2024-T351

    DEFF Research Database (Denmark)

    Jariyaboon, M; Davenport, A.J.; Ambat, Rajan

    2007-01-01

    The effect of welding parameters (rotation speed and travel speed) on the corrosion behaviour of friction stir welds in the high strength aluminium alloy AA2024-T351 was investigated. It was found that rotation speed plays a major role in controlling the location of corrosion attack. Localised...

  14. Corrosion cracking

    International Nuclear Information System (INIS)

    Goel, V.S.

    1985-01-01

    This book presents the papers given at a conference on alloy corrosion cracking. Topics considered at the conference included the effect of niobium addition on intergranular stress corrosion cracking, corrosion-fatigue cracking in fossil-fueled-boilers, fracture toughness, fracture modes, hydrogen-induced thresholds, electrochemical and hydrogen permeation studies, the effect of seawater on fatigue crack propagation of wells for offshore structures, the corrosion fatigue of carbon steels in seawater, and stress corrosion cracking and the mechanical strength of alloy 600

  15. Effect of cerium addition on the corrosion behaviour of carbon-alloyed iron aluminides

    International Nuclear Information System (INIS)

    Sriram, S.; Balasubramaniam, R.; Mungole, M.N.; Bharagava, S.; Baligidad, R.G.

    2006-01-01

    The effect of Ce addition on the microstructure and corrosion behavior of carbon-alloyed iron aluminides Fe-20.0Al-2.0C, Fe-18.5Al-3.6C and Fe-19.2Al-3.3C-0.07Ce (in at.%) has been studied. The potentiodynamic polarization behaviour of the alloys was evaluated in freely aerated 0.25 mol/l H 2 SO 4 . A 0.05% C steel was used for comparison purposes. All the alloys exhibited active-passive behaviour in the acidic solution. The addition of Ce destroyed passivity as indicated by lower breakdown potentials in polarization studies. This has been related to the finer distribution of the carbides in the microstructure. Corrosion rates were evaluated by immersion testing. The iron aluminide with Ce addition exhibited a lower corrosion rate compared to the aluminides without Ce addition. This has been attributed to modifications in surface film with Ce addition. Scanning electron microscopy of corroded surfaces indicated that the carbon-alloyed intermetallics were susceptible to localized galvanic corrosion due to the presence of carbides in the microstructure

  16. Electrochemical behaviour of silica basic hybrid coatings deposited on stainless steel by dipping and EPD

    International Nuclear Information System (INIS)

    Castro, Y.; Duran, A.; Damborenea, J.J.; Conde, A.

    2008-01-01

    The aim of this work is the characterisation of the corrosion behaviour of stainless steel (AISI 304) substrates coated by dipping and electrophoretic deposition (EPD) from a sol-gel basic sol. Particulate silica sols (labelled NaSi) were prepared by basic catalysis from ethyltriethoxysilane (TEOS), methyltriethoxysilane (MTES) and sodium hydroxide. Coatings between 2 and 10 μm were prepared by using concentrated and diluted sols by dipping and EPD process and the corrosion behaviour of the coated substrates were studied through potentiodynamic and impedance spectroscopy measurements (EIS). Potentiodynamic studies of coatings produced by dipping reveal a strong dependence of the protective properties with the concentration of the sol. This behaviour was confirmed by EIS showing that only the coatings obtained from concentrated sol present enough protective properties. On the contrary, EPD coatings prepared from diluted NaSi sol showed an excellent corrosion resistance, maintaining a pure capacitive behaviour for long periods of immersion. EPD deposition is thus proposed as a good alternative method for obtaining thicker and denser coatings with good protective properties from dilute and stable sols

  17. Corrosion behaviour of alloy 31 - UNS N08031 - under conditions of oil and gas production

    Energy Technology Data Exchange (ETDEWEB)

    Kloewer, J. [ThyssenKrupp VDM France SARL, Rueil-Malmaison (France); Schlerkmann, H.; Poepperling, R. [Mannesmann Forschungsinstitut, Duisburg (Germany)

    2002-10-01

    The corrosion behaviour of alloy 31 (UNS N08031-31Ni-27Cr-6.5Mo-1.2Cu-0.2N-bal.Fe) was tested in laboratory and field tests in seawater with and without additions of CO{sub 2} and/or H{sub 2}S in slow strain rate tests, and in SSC (Sulphide Stress Corrosion) tests according to NACE MR0175. The results demonstrate a high resistance of alloy 31 to localised corrosion. Due to the high chromium and molybdenum concentration, its resistance to pitting and crevice corrosion in chloride-contaminated seawater is significantly higher than that of alloy 28 and alloy 825 and it equals that of typical nickel base alloys like alloy 625. Alloy 31 is not sensitive to chloride-induced stress corrosion cracking, either with or without H{sub 2}S, or sulphide stress cracking. Alloy 31 is approved for sour gas applications up to LEVEL VI in NACE MR0175. The combination of properties makes alloy 31 an attractive choice for components in oil and gas production including wirelines, umbilicals, tubing, piping and topside application. (orig.)

  18. Inhibitive Behaviour of Corrosion of Aluminium Alloy in NaCl by Mangrove Tannin

    International Nuclear Information System (INIS)

    Solhan Yahya; Afidah Abdul Rahim; Affaizza Mohd Shah; Rohana Adnan

    2011-01-01

    Anticorrosion potential of mangrove tannins on aluminium alloys AA6061 in NaCl solution has been studied using potentiodynamic polarisation method and scanning electron microscopy (SEM). The study was carried out in different pH of corrosive medium in the absence and presence of various concentrations of tannin. The corrosion inhibition behaviour of the mangrove tannin on AA6061 aluminium alloy corrosion was found to be dependant on the pH of NaCl solution. Our results showed that the inhibition efficiency increased with increasing tannins concentration in chloride solution at pH 6. Treatment of aluminium alloy 6061 with all concentrations of mangrove tannins reduced the current density, thus decreased the corrosion rate. Tannins behaved as mixed inhibitors at pH 6 and reduction in current density predominantly affected in cathodic reaction. Meanwhile, at pH 12, addition of tannins shifted the corrosion potential to more cathodic potentials and a passivating effect was observed in anodic potentials. SEM studies have shown that the addition of tannins in chloride solution at pH 12 reduced the surface degradation and the formation of pits. (author)

  19. The influence of water pH and F- ions contamination in Zirconium alloys corrosion behaviour

    International Nuclear Information System (INIS)

    Radulescu, M.; Pirvan, I.

    1983-01-01

    The water chemistry of the primary circuit is one of the most important factors of influence on the corrosion behaviour in the PHWR of the fuel cladding materials: Zircaloy-2 and Zircaloy-4. We studied the influence of the water pH adjusted by LiOH. In this purpose were performed 3 days tests in lithiated water (pH: 10 - 13,5) at 360 deg. C and 180 bar on Zy-2 and Zy-4 samples. The gravimetric and micrographic results have shown that a LiOH concentration - ions as impurities in the primary circuit, we studied Zy-2 corrosion behaviour by 3 days tests in 1mg F - /l and 10mg F - /1 solutions, at 300 deg. C, 350 deg. C and 400 deg. C

  20. Corrosion behaviour of 8090 alloy in saline solution with moderate aggressiveness

    International Nuclear Information System (INIS)

    Conde, A.; Damborenea, J.J.

    1998-01-01

    Corrosion studies of Al-Li alloys are not so extensive and concentrate almost exclusively on atmospheric exposure tests and accelerated laboratory tests due to the fact they provide a reasonable approximation to the real behaviour of the alloy in service conditions. This paper attempts to establish a correlation between the evolution of the impedance diagrams and the process of the attack undergone by a commercial 8090 T8171 alloy, with the aim of establishing the kinetics of the corrosion process. After 100 h of immersion, samples showed only a slight intergranular attack. As a results of the low aggressiveness of the solution no major deviations from the ideal behaviour described by the Randles circuit are expected in the impedance plots. After 50 hours of testing, the impedance diagram evolves towards two semicircles which seem to be related with the charge transfer and ionic migration through the oxide layer and the adsorption of electrolyte anions. (Author) 7 refs

  1. Mathematical modelling of the corrosion and leaching behaviour of cemented waste forms

    International Nuclear Information System (INIS)

    Kienzler, B.

    1985-05-01

    A theoretical model is presented which allows to calculate the leaching of radionuclides and the corrosion of cemented waste forms in contact with water or brine. The model computes both the behaviour of specimens in laboratory-scale experiments and provides a forecast of the behaviour of waste forms in the case of an accidental drowning of a repository. The mathematical formalism employed describes leaching and corrosion on the basis of diffusion and dissolution processes and of chemical reactions. The mathematical formalism is coded in FORTRAN77. This report includes the documentation of the 'DIFMOD' computer code with the associated 'DIFPLO' plot program and the input manual of both programs. Finally application of the model is demonstrated by some examples allowing interpretation of experimental data. (orig.) [de

  2. Evaluation of structural behaviour and corrosion resistant of austenitic AISI 304 and duplex AISI 2304 stainless steel reinforcements embedded in ordinary Portland cement mortars; Evaluacion del comportamiento estructural y de resistencia a la corrosion de armaduras de acero inoxidable austenitico AISI 304 y duplex AISI 2304 embebidas en morteros de cemento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Medina, E.; Cobo, A.; Bastidas, D. M.

    2012-07-01

    The mechanical and structural behaviour of two stainless steels reinforcements, with grades austenitic EN 1.4301 (AISI 304) and duplex EN 1.4362 (AISI 2304) have been studied, and compared with the conventional carbon steel B500SD rebar. The study was conducted at three levels: at rebar level, at section level and at structural element level. The different mechanical properties of stainless steel directly influence the behaviour at section level and structural element level. The study of the corrosion behaviour of the two stainless steels has been performed by electrochemical measurements, monitoring the corrosion potential and the lineal polarization resistance (LPR), of reinforcements embedded in ordinary Portland cement (OPC) mortar specimens contaminated with different amount of chloride over one year time exposure. Both stainless steels specimens embedded in OPC mortar remain in the passive state for all the chloride concentration range studied after one year exposure. (Author) 26 refs.

  3. Electrochemical noise of the erosion-corrosion of copper in relation with its hydrodynamic parameters; Ruido electroquimico de la erosion-corrosion en cobre: su relacion con los parametros hidrodinamicos

    Energy Technology Data Exchange (ETDEWEB)

    Castaneda, I.; Romero, M.; Malo, J.M.; Uruchurtu, J.

    2010-07-01

    This work presents the electrochemical noise results obtained of the surface degradation on copper, due to erosion corrosion phenomena, which were a function of the hydrodynamic parameters of the system (fluid movement). A modified rotating cylinder (RC) comprising three ring electrodes under two rotating speeds (880 and 1750 rpm with a Reynolds numbers 1486 Re and 2972 Re, respectively) were used. Characteristic electrochemical noise spectra as a function of the hydrodynamic parameters were found, as well as surface attack intensities the noise signal. An increase and a more uniform attack due to particle impact was related to larger particle size and lesser erosion corrosion intensity, in the form of more localized attack over the surface, was obtained for smaller ones. Erosion corrosion attack presents characteristic electrochemical current and potential noise signals, according to the laminar or transitional turbulent regime and particle size added. (Author).

  4. CORROSION RESISTANCE OF ORGANOMETALLIC COATING APLICATED IN FUEL TANKS USING ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY IN BIOFUEL – PART I

    Directory of Open Access Journals (Sweden)

    Milene Adriane Luciano

    2014-10-01

    Full Text Available Nowadays, the industry has opted for more sustainable production processes, and the planet has also opted for new energy sources. From this perspective, automotive tanks with organometallic coatings as well as a partial substitution of fossil fuels by biofuels have been developed. These organometallic coated tanks have a zinc layer, deposited by a galvanizing process, formed between the steel and the organometallic coating. This work aims to characterize the organometallic coating used in metal automotive tanks and evaluate their corrosion resistance in contact with hydrated ethyl alcohol fuel (AEHC. For this purpose, the resistance of all layers formed between Zinc and EEP steel and also the tin coated steel, which has been used for over thirty years, were evaluated. The technique chosen was the Electrochemical Impedance Spectroscopy. The results indicated an increase on the corrosion resistance when organometallic coatings are used in AEHC medium. In addition to that, these coatings allow an estimated 25% reduction in tanks production costs.

  5. MRI-compatible Nb-60Ta-2Zr alloy for vascular stents: Electrochemical corrosion behavior in simulated plasma solution.

    Science.gov (United States)

    Li, Hui-Zhe; Zhao, Xu; Xu, Jian

    2015-11-01

    Using revised simulated body fluid (r-SBF), the electrochemical corrosion behavior of an Nb-60Ta-2Zr alloy for MRI compatible vascular stents was characterized in vitro. As indicated by XPS analysis, the surface passive oxide film of approximately 1.3nm thickness was identified as a mixture of Nb2O5, Ta2O5 and ZrO2 after immersion in the r-SBF. The Nb-60Ta-2Zr alloy manifests a low corrosion rate and high polarization resistance similar to pure Nb and Ta, as shown by the potentiodynamic polarization curves and EIS. Unlike 316L stainless steel and the L605 Co-Cr alloy, no localized corrosion has been detected. Semiconducting property of passive film on the Nb-60Ta-2Zr alloy was identified as the n-type, with growth mechanism of high-field controlled growth. The excellent corrosion resistance in simulated human blood enviroment renders the Nb-60Ta-2Zr alloy promising as stent candidate material. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Constructing superhydrophobic WO3@TiO2 nanoflake surface beyond amorphous alloy against electrochemical corrosion on iron steel

    Science.gov (United States)

    Yu, S. Q.; Ling, Y. H.; Wang, R. G.; Zhang, J.; Qin, F.; Zhang, Z. J.

    2018-04-01

    To eliminate harmful localized corrosion, a new approach by constructing superhydrophobic WO3@TiO2 hierarchical nanoflake surface beyond FeW amorphous alloy formed on stainless steel was proposed. Facile dealloying and liquid deposition was employed at low temperature to form a nanostructured layer composing inner WO3 nanoflakes coated with TiO2 nanoparticles (NPs) layer. After further deposition of PFDS on nanoflakes, the contact angle reached 162° while the corrosion potential showed a negative shift of 230 mV under illumination, resulting in high corrosion resistance in 3.5 wt% NaCl solution. The tradeoff between superhydrophobic surface and photo-electro response was investigated. It was found that this surface feature makes 316 SS be immune to localized corrosion and a pronounced photo-induced process of electron storage/release as well as the stability of the functional layer were detected with or without illumination, and the mechanism behind this may be related to the increase of surface potential due to water repellence and the delayed cathodic protection of semiconducting coating derived mainly from the valence state changes of WO3. This study demonstrates a simple and low-cost electrochemical approach for protection of steel and novel means to produce superhydrophobic surface and cathodic protection with controllable electron storage/release on engineering scale.

  7. Electrochemical Behaviour of a PPy(DBS)/Polyacrylonitrile (PAN):LITF:EC:PC/ Li Cell

    DEFF Research Database (Denmark)

    Vidanapathirana, K.; Careem, M.A.; Skaarup, Steen

    2006-01-01

    The electrochemical behaviour of Li rechargeable cells with Polypyrrole (PPy) as the cathode material was investigated using cyclic voltammetry. The PPy used was doped with the large surfactant anion dodecyl benzenesulphonate (DBS-). The cells were constructed with PAN:LiTF:EC:PC gel electrolyte...... with Li as anode. The results indicate that during the first reduction, cations are inserted into the PPy film forming LiDBS neutral salt. During the next oxidation/reduction cycles, the mechanism then switches to anion movement. Cyclic voltammetry studies also verified that complete electrochemical...

  8. ELECTROCHEMICAL STUDIES OF CARBON STEEL CORROSION IN HANFORD DOUBLE SHELL TANK (DST) WASTE

    Energy Technology Data Exchange (ETDEWEB)

    DUNCAN, J.B.; WINDISCH, C.F.

    2006-10-13

    This paper reports on the electrochemical scans for the supernatant of Hanford double-shell tank (DST) 241-SY-102 and the electrochemical scans for the bottom saltcake layer for Hanford DST 241-AZ-102. It further reports on the development of electrochemical test cells adapted to both sample volume and hot cell constraints.

  9. Electrochemical Study of AISI C1018 Steel in Methanesulfonic Acid Containing an Acetylenic Alcohol-Based Corrosion Inhibitor Formulation.

    Science.gov (United States)

    Finšgar, Matjaž; Jackson, Jennifer

    2016-10-01

    In this work, the electrochemical potentiodynamic behavior of AISI C1018 lower-grade steel material was investigated in 20 wt.% methanesulfonic acid (MSA) solutions with or without different components to design corrosion inhibitor formulations based on acetylenic alcohol, cinnamaldehyde, 1-dodecylpyridinium chloride, and methanol. MSA has recently been considered as a new potential acid to be used in the matrix stimulation procedure and in well cleaning. It is demonstrated that AISI C1018 steel MSA needs to be inhibited. Inhibition type is determined for single components as well as for formulations. © 2015 Society for Laboratory Automation and Screening.

  10. Tribological and corrosion behaviour of electroless Ni-B coating possessing a blackberry like structure

    Science.gov (United States)

    Bülbül, Ferhat; Altun, Hikmet; Küçük, Özkan; Ezirmik, Vefa

    2012-08-01

    This study aims to evaluate the tribological and corrosion properties of the electroless Ni-B coating deposited on AISI 304 stainless steels. The microstructure of the coating was characterized using x-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS). XRD analysis revealed that the prepared coating possessed an amorphous character. SEM-EDS investigation also indicated that a non-stoichiometric Ni-B coating was deposited with a columnar growth mechanism on the stainless steel substrate and the morphology of the growth surface was blackberry-like. The hardness and tribological properties were characterized by microhardness and a pin-on-disc wear test. The electroless Ni-B coated sample had a higher degree of hardness, a lower friction coefficient and a lower wear rate than the uncoated substrate. The electrochemical potentiodynamic polarization method was used to evaluate the corrosion resistance of the coating. The electroless Ni-B coating offered cathodic protection on the substrate by acting as a sacrificial anode although it was electrochemically more reactive than the stainless steel substrate.

  11. Effect of replacement of vanadium by iron on the electrochemical behaviour of titanium alloys in simulated physiological media

    Directory of Open Access Journals (Sweden)

    Mareci, D.

    2009-02-01

    Full Text Available The electrochemical behaviour of Ti6Al4V, Ti6Al3.5Fe and Ti5Al2.5Fe alloys has been evaluated in Ringer’s solution at 25 °C. The effect of the substitution of vanadium in Ti6Al4V alloy has been specifically addressed. The evaluation of the corrosion resistance was carried out through the analysis of the open circuit potential variation with time, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS tests. Very low current densities were obtained (order of nA/cm2 from the polarization curves and EIS, indicating a typical passive behaviour for all investigated alloys. The EIS results exhibited relative capacitive behaviour (large corrosion resistance with phase angle close to –80° and relative high impedance values (order of 105 Ω•cm2 at low and medium frequencies, which are indicative of the formation of a highly stable film on these alloys in Ringer’s solution. In conclusion, the electrochemical behaviour of Ti6Al4V is not affected by the substitution of vanadium with iron.

    El comportamiento electroquímico de las aleaciones Ti6Al4V, Ti6Al3.5Fe y Ti5Al2.5Fe fue evaluado en una disolución Ringer a 25 °C. Se ha estudiado especialmente el efecto de la sustitución del vanadio en la aleación Ti6Al4V. La evaluación de la resistencia a la corrosión se ha llevado a cabo a través del análisis de la variación del potencial de un circuito abierto con el tiempo, las curvas de polarización potenciodinámicas y los ensayos de espectroscopía de impedancia electroquímica (EIS. Se han obtenido densidades de corriente muy bajas (del orden de nA/cm2 en las curvas de polarización y EIS, indicando un comportamiento pasivo típico para todas las aleaciones investigadas. Los resultados de la EIS mostraron un comportamiento capacitivo relativo (gran resistencia a la corrosión con ángulos de fase próximos a –80° y valores de impedancia relativamente altos (del orden de

  12. Electrochemical passivation behaviour of nanocrystalline Fe80Si20 ...

    Indian Academy of Sciences (India)

    Passivation behaviour of nanocrystalline coating (Fe80Si20) obtained by in situ mechanical alloying route is studied and compared with that of the commercial pure iron and cast Fe80Si20 in sodium borate buffer solution at two different pH values (7.7 and 8.4). The coating reveals single passivation at a pH of 7.7 and ...

  13. Electrochemical behaviour of TiO{sub 2} reinforced Al 7075 composite

    Energy Technology Data Exchange (ETDEWEB)

    Karunanithi, R., E-mail: karunaponni@gmail.com; Bera, Supriya; Ghosh, K.S., E-mail: ksghosh2001@yahoo.co.uk

    2014-12-15

    Graphical abstract: - Highlights: • Clustering of TiO{sub 2} particle and porosity increased with increasing TiO{sub 2}. • Coarse and numerous very fine η′ and η precipitates in T6 temper composite. • Shifting corrosion potential to noble direction with increasing TiO{sub 2}. • Corrosion is maximum for 30 vol.% TiO{sub 2} composite and least for 7075 alloy. • Pitting damage greater with the increasing TiO{sub 2}. - Abstract: Microstructures of sintered Al 7075 alloy and Al 7075 alloy reinforced with varying TiO{sub 2} composites exhibited uniform distribution of TiO{sub 2} particles, but clustering and porosity have increased with TiO{sub 2} content. TEM micrographs of the Al 7075 alloy and Al 7075 + TiO{sub 2} composite of peak aged T6 (PA) temper showed some coarse and numerous very fine η′ (MgZn{sub 2}) precipitates, and equilibrium η (MgZn{sub 2}) precipitates along the grain boundaries. Potentiodynamic electrochemical polarisation studies on the Al 7075 alloy of different tempers and Al 7075 + TiO{sub 2} composites in 3.5 wt.% NaCl solution showed that the corrosion potentials (E{sub corr}) have shifted towards noble direction with the addition of TiO{sub 2}, and there is an increase of corrosion current density (i{sub corr}) beyond 10 vol.% TiO{sub 2} in the composites. This is attributed to the increase in particle-matrix interface areas enhancing pitting corrosion. Optical micrographs of the corroded surface of 30% TiO{sub 2} composites exhibited maximum pitting damage.

  14. Construction of an external electrode for determination of electrochemical corrosion potential in normal operational conditions of an BWR type reactor for hot cells

    International Nuclear Information System (INIS)

    Aguilar T, J.A.; Rivera M, H.; Hernandez C, R.

    2001-01-01

    The behavior of the corrosion processes at high temperature requires of external devices that being capable to resist a temperature of 288 Centigrade and a pressure of 80 Kg/cm 2 , to give stable and reproducible results of some variable and resisting physically and chemically the radiation. The external electrode of Ag/AgCl fulfils all the requirements in the determination of the electrochemical corrosion potential under normal operational conditions of a BWR type reactor in hot cells. (Author)

  15. An electrochemical study of the effect of Li on the corrosion behavior of Ni3Al intermetallic alloy in molten (Li + K) carbonate

    International Nuclear Information System (INIS)

    Gonzalez-Rodriguez, J.G.; Mejia, E.; Lucio-Garcia, M.A.; Salinas-Bravo, V.M.; Porcayo-Calderon, J.; Martinez-Villafane, A.

    2009-01-01

    A study of the effect of lithium content (1, 3 and 5 wt.%) and heat treatment (400 deg. C during 144 h) on the corrosion behavior of Ni 3 Al alloy has been carried out in a 62 mol.%Li 2 CO 3 -38 mol.%K 2 CO 3 mixture at 650 deg. C using electrochemical techniques. Employed electrochemical techniques included potentiodynamic polarization curves, linear polarization resistance, LPR, electrochemical impedance spectroscopy, EIS, and electrochemical noise, measurements EN. Results have shown that the alloys exhibited an active-passive behavior regardless of the heat treatment. For alloys without heat treatment, the most corrosion resistant was the Ni 3 Al base alloy, but when they were heat treated, the most corrosion resistant was the alloy containing 3%Li. EIS results showed that for short immersion tests, the corrosion process was under diffusion control, but for longer exposure times, the presence of a protective scale was evident. All the alloys were highly susceptible to a localized type of corrosion according to EN measurements and supported by SEM micrographs.

  16. An electrochemical study of the effect of Li on the corrosion behavior of Ni{sub 3}Al intermetallic alloy in molten (Li + K) carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Rodriguez, J.G. [Universidad Autonoma del Estado de Morelos, CIICAp, Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Mor. (Mexico); Centro de Investigacion en Materiales Avanzados. S.C. Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chih. (Mexico)], E-mail: ggonzalez@uaem.mx; Mejia, E. [Universidad Autonoma del Estado de Morelos, CIICAp, Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Mor. (Mexico); Lucio-Garcia, M.A. [Centro de Investigacion en Materiales Avanzados. S.C. Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chih. (Mexico); Salinas-Bravo, V.M.; Porcayo-Calderon, J. [Instituto de Inv. Electricas, Gerencia de Procesos Termicos, Reforma 108, Temixco, Mor. (Mexico); Martinez-Villafane, A. [Centro de Investigacion en Materiales Avanzados. S.C. Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chih. (Mexico)

    2009-08-15

    A study of the effect of lithium content (1, 3 and 5 wt.%) and heat treatment (400 deg. C during 144 h) on the corrosion behavior of Ni{sub 3}Al alloy has been carried out in a 62 mol.%Li{sub 2}CO{sub 3}-38 mol.%K{sub 2}CO{sub 3} mixture at 650 deg. C using electrochemical techniques. Employed electrochemical techniques included potentiodynamic polarization curves, linear polarization resistance, LPR, electrochemical impedance spectroscopy, EIS, and electrochemical noise, measurements EN. Results have shown that the alloys exhibited an active-passive behavior regardless of the heat treatment. For alloys without heat treatment, the most corrosion resistant was the Ni{sub 3}Al base alloy, but when they were heat treated, the most corrosion resistant was the alloy containing 3%Li. EIS results showed that for short immersion tests, the corrosion process was under diffusion control, but for longer exposure times, the presence of a protective scale was evident. All the alloys were highly susceptible to a localized type of corrosion according to EN measurements and supported by SEM micrographs.

  17. Atmospheric corrosion in subtropical areas: XRD and electrochemical study of zinc atmospheric corrosion products in the province of Santa Cruz de Tenerife (Canary Islands, Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Morales, J. [Departamento de Quimica Fisica, Universidad de La Laguna, 38071 La Laguna, Tenerife (Spain)]. E-mail: jmorales@ull.es; Diaz, F. [Departamento de Quimica Fisica, Universidad de La Laguna, 38071 La Laguna, Tenerife (Spain); Hernandez-Borges, J. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de La Laguna, 38071 La Laguna, Tenerife (Spain); Gonzalez, S. [Departamento de Quimica Fisica, Universidad de La Laguna, 38071 La Laguna, Tenerife (Spain)

    2006-02-15

    In the present paper, zinc sheets have been exposed for 4 years to the action of different atmospheres in 35 test sites located in the province of Santa Cruz de Tenerife, Canary Islands, Spain. Corrosion products formed on the surface of the samples have been identified by means of X-ray diffraction (XRD) for the first and second year of exposure. Zincite, hydrozincite, simonkolleite, zinc chlorohydroxysulphate, zinc oxysulphate and zinc hydroxysulphate have been identified in the test sheets. Preliminary results of an electrochemical study of the breakdown potential of zinc samples are also presented in order to test the protective effect of the film formed on the surface of the samples. It was found that the protective effect of this film increases linearly with exposure time.

  18. The corrosion and biological behaviour of titanium alloys in the presence of human lymphoid cells and MC3T3-E1 osteoblasts

    International Nuclear Information System (INIS)

    Zhang Yumei; Zhao Yimin; Chai Feng; Hildebrand, Hartmut F; Hornez, Jean-Christophe; Li, Chang Liang; Traisnel, Michel

    2009-01-01

    Corrosion behaviour of biomedical alloys is generally determined in mineral electrolytes: unbuffered NaCl 0.9% (pH 7.4) or artificial saliva (pH 6.8). The assays with exclusive utilization of these electrolytes are of low relevance for the biological condition, to which the alloys will be exposed once implanted in the human organism. As an approach to the biological situation regarding the interaction of proteins, electrolytes and metals, we added the RPMI cell culture medium containing foetal calf serum as a biological electrolyte (pH 7.0). The analysis of corrosion behaviour was also performed in the presence of human lymphoid cells (CEM). The rest potential (E r ) and the global polarization were determined on cp-Ti, micro-arc oxidized cp-Ti (MAO-Ti), four different Ti-alloys (Ti6Al4V, Ti12Zr, Ti(AlMoZr), Ti(NbTaZr)) and 316L stainless steel. The 316L exhibited an appropriate E r and a good passive current density (I p ), but a high corrosion potential (E c ) and a very low breakdown potential (E b ) in all electrolytes. All Ti-alloys exhibited a much better electrochemical behaviour: better E r and E c and very high E b . No significant differences of the above parameters existed between the Ti-alloys, except for Zr-containing alloys that showed better corrosion behaviour. A remarkable difference, however, was stated with respect to the electrolytes. NaCl 0.9% induced strong variations between the Ti-alloys. More homogeneous results were obtained with artificial saliva and RPMI medium, which induced a favourable E c and an increased I p . The presence of cells further decreased these values. The unbuffered NaCl solution seems to be less appropriate for the analysis of corrosion of metals. Additional in vitro biological assessments with CEM cell suspensions and MC3T3-E1 osteoblasts confirmed the advantages of the Ti(AlMoZr) and Ti(NbTaZr) alloys with an improved cell proliferation and vitality rate.

  19. The corrosion and biological behaviour of titanium alloys in the presence of human lymphoid cells and MC3T3-E1 osteoblasts.

    Science.gov (United States)

    Zhang, Yu Mei; Chai, Feng; Hornez, Jean-Christophe; Li, Chang Liang; Zhao, Yi Min; Traisnel, Michel; Hildebrand, Hartmut F

    2009-02-01

    Corrosion behaviour of biomedical alloys is generally determined in mineral electrolytes: unbuffered NaCl 0.9% (pH 7.4) or artificial saliva (pH 6.8). The assays with exclusive utilization of these electrolytes are of low relevance for the biological condition, to which the alloys will be exposed once implanted in the human organism. As an approach to the biological situation regarding the interaction of proteins, electrolytes and metals, we added the RPMI cell culture medium containing foetal calf serum as a biological electrolyte (pH 7.0). The analysis of corrosion behaviour was also performed in the presence of human lymphoid cells (CEM). The rest potential (Er) and the global polarization were determined on cp-Ti, micro-arc oxidized cp-Ti (MAO-Ti), four different Ti-alloys (Ti6Al4V, Ti12Zr, Ti(AlMoZr), Ti(NbTaZr)) and 316L stainless steel. The 316L exhibited an appropriate Er and a good passive current density (Ip), but a high corrosion potential (Ec) and a very low breakdown potential (Eb) in all electrolytes. All Ti-alloys exhibited a much better electrochemical behaviour: better Er and Ec and very high Eb. No significant differences of the above parameters existed between the Ti-alloys, except for Zr-containing alloys that showed better corrosion behaviour. A remarkable difference, however, was stated with respect to the electrolytes. NaCl 0.9% induced strong variations between the Ti-alloys. More homogeneous results were obtained with artificial saliva and RPMI medium, which induced a favourable Ec and an increased Ip. The presence of cells further decreased these values. The unbuffered NaCl solution seems to be less appropriate for the analysis of corrosion of metals. Additional in vitro biological assessments with CEM cell suspensions and MC3T3-E1 osteoblasts confirmed the advantages of the Ti(AlMoZr) and Ti(NbTaZr) alloys with an improved cell proliferation and vitality rate.

  20. The corrosion and biological behaviour of titanium alloys in the presence of human lymphoid cells and MC3T3-E1 osteoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yumei; Zhao Yimin [School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Chai Feng; Hildebrand, Hartmut F [Groupe de Recherche sur les Biomateriaux, Faculte de Medecine, F-59045 Lille cedex (France); Hornez, Jean-Christophe [Laboratoire des Materiaux et Procedes (LMP), EA 2443, UVHC, 59600 Maubeuge (France); Li, Chang Liang [Northwest Institute for Nonferrous Metal Research, Xi' an 710016 (China); Traisnel, Michel, E-mail: zhaoym@fmmu.edu.c, E-mail: fhildebrand@univ-lille2.f [Ecole Nationale Superieure de Chimie de Lille, UMR CNRS 8008, 59652 Villeneuve d' Ascq (France)

    2009-02-15

    Corrosion behaviour of biomedical alloys is generally determined in mineral electrolytes: unbuffered NaCl 0.9% (pH 7.4) or artificial saliva (pH 6.8). The assays with exclusive utilization of these electrolytes are of low relevance for the biological condition, to which the alloys will be exposed once implanted in the human organism. As an approach to the biological situation regarding the interaction of proteins, electrolytes and metals, we added the RPMI cell culture medium containing foetal calf serum as a biological electrolyte (pH 7.0). The analysis of corrosion behaviour was also performed in the presence of human lymphoid cells (CEM). The rest potential (E{sub r}) and the global polarization were determined on cp-Ti, micro-arc oxidized cp-Ti (MAO-Ti), four different Ti-alloys (Ti6Al4V, Ti12Zr, Ti(AlMoZr), Ti(NbTaZr)) and 316L stainless steel. The 316L exhibited an appropriate E{sub r} and a good passive current density (I{sub p}), but a high corrosion potential (E{sub c}) and a very low breakdown potential (E{sub b}) in all electrolytes. All Ti-alloys exhibited a much better electrochemical behaviour: better E{sub r} and E{sub c} and very high E{sub b}. No significant differences of the above parameters existed between the Ti-alloys, except for Zr-containing alloys that showed better corrosion behaviour. A remarkable difference, however, was stated with respect to the electrolytes. NaCl 0.9% induced strong variations between the Ti-alloys. More homogeneous results were obtained with artificial saliva and RPMI medium, which induced a favourable E{sub c} and an increased I{sub p}. The presence of cells further decreased these values. The unbuffered NaCl solution seems to be less appropriate for the analysis of corrosion of metals. Additional in vitro biological assessments with CEM cell suspensions and MC3T3-E1 osteoblasts confirmed the advantages of the Ti(AlMoZr) and Ti(NbTaZr) alloys with an improved cell proliferation and vitality rate.

  1. Localized corrosion behaviour in simulated human body fluids of commercial Ni-Ti orthodontic wires.

    Science.gov (United States)

    Rondelli, G; Vicentini, B

    1999-04-01

    The corrosion performances in simulated human body fluids of commercial equiatomic Ni-Ti orthodontic wires having various shape and size and produced by different manufacturers were evaluated; for comparison purposes wires made of stainless steel and of cobalt-based alloy were also examined. Potentiodynamic tests in artificial saliva at 40 degrees C indicated a sufficient pitting resistance for the Ni-Ti wires, similar to that of cobalt-based alloy wire; the stainless steel wire, instead, exhibited low pitting potential. Potentiodynamic tests at 40 degrees C in isotonic saline solution (0.9% NaCl) showed, for Ni-Ti and stainless steel wires, pitting potential values in the range approximately 200-400 mV and approximately 350 mV versus SCE, respectively: consequently, according to literature data (Hoar TP, Mears DC. Proc Roy Soc A 1996;294:486-510), these materials should be considered potentially susceptible to pitting; only the cobalt-based alloy should be immune from pitting. The localized corrosion potentials determined in the same environment by the ASTM F746 test (approximately 0-200 mV and 130 mV versus SCE for Ni-Ti and stainless steel, respectively) pointed out that for these materials an even higher risk of localized corrosion. Slight differences in localized corrosion behaviour among the various Ni-Ti wires were detected.

  2. Comparative Studies on microstructure, mechanical and corrosion behaviour of DMR 249A Steel and its welds

    Science.gov (United States)

    Mohammed, Raffi; Dilkush; Madhusudhan Reddy, G.; Srinivasa Rao, K.

    2018-03-01

    DMR249A Medium strength (low carbon) Low-alloy steels are used as structural components in naval applications due to its low cost and high availability. An attempt has been made to weld the DMR 249A steel plates of 8mm thickness using shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW). Welds were characterized for metallography to carry out the microstructural changes, mechanical properties were evaluated using vickers hardness tester and universal testing machine. Potentio-dynamic polarization tests were carried out to determine the pitting corrosion behaviour. Constant load type Stress corrosion cracking (SCC) testing was done to observe the cracking tendency of the joints in a 3.5%NaCl solution. Results of the present study established that SMA welds resulted in formation of relatively higher amount of martensite in ferrite matrix when compared to gas tungsten arc welding (GTAW). It is attributed to faster cooling rates achieved due to high thermal efficiency. Improved mechanical properties were observed for the SMA welds and are due to higher amount of martensite. Pitting corrosion and stress corrosion cracking resistance of SMA welds were poor when compared to GTA welds.

  3. Corrosion of Steel in Concrete – Potential Monitoring and Electrochemical Impedance Spectroscopy during Corrosion Initiation and Propagation

    DEFF Research Database (Denmark)

    Küter, Andre; Mason, Thomas O.; Geiker, Mette Rica

    2005-01-01

    included grit blasting, electrochemical and hydrochloric acid cleaning (HCl) as well as weathering. The results indicate that the investigated treatments of the carbon steel surface have no major effect on the initiation period, which was approximately 20 days under the actual conditions. The galvanized......A reinforced mortar specimen that allows potential measurements and electrochemical impedance spectroscopy (EIS) immediately after preparation was designed and tested. The specimen consists of a mortar cylinder with a central rebar and a concentric arrangement of embedded Ru/Ir activated titanium...... wires. The wires can act as both reference and counter electrode during EIS and, thus, no external electrode is required. The defined geometry solves reproducibility problems involved with application of an external reference electrode for EIS. Changes of the electromotive force (EMF) between rebar...

  4. Corrosion Inhibition on SAE 1010 Steel by Nanoscale Exopolysaccharides Coatings Determined by Electrochemical and Surface Characterization

    Science.gov (United States)

    Plating, painting and the application of enamel are the most common anti-corrosion treatments. They are effective by providing a barrier of corrosion resistant material between the damaging environment and the structural material. Coatings start failing rapidly if scratched or damaged because a co...

  5. Ship ballast tanks a review from microbial corrosion and electrochemical point of view

    NARCIS (Netherlands)

    Heyer, A.; D'Souza, F.; Morales, C.F.L.; Ferrari, G.; Mol, J.M.C.; Wit, J.H.W. de

    2013-01-01

    Microbiologically Influenced Corrosion (MIC) is the term used for the phenomenon in which corrosion is initiated and/or accelerated by the activities of microorganisms. MIC is a very serious problem for the ship industry as it reduces structural lifetime in combination with safety risks for

  6. Influence of the surface finishing on electrochemical corrosion characteristics of AISI 316L stainless steel

    Czech Academy of Sciences Publication Activity Database

    Dundeková, S.; Hadzima, B.; Fintová, Stanislava

    2015-01-01

    Roč. 22, č. 2 (2015), s. 77-84 ISSN 1335-0803 Institutional support: RVO:68081723 Keywords : AISI 316L stainless steel * EIS * Corrosion Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://ojs.mateng.sk/index.php/Mateng/article/view/167/278

  7. Long-term corrosion behaviour of low-/medium-level waste packages

    International Nuclear Information System (INIS)

    Jendras, M.; Bach, F.W.; Behrens, S.; Birr, Ch.; Hassel, Th.

    2009-01-01

    Full text of publication follows: Storage of low- and medium-level radioactive waste requires safe packages. This means that all materials used for the manufacturing of such packages have to show a sufficient resistance especially against corrosive attacks. Since these packages are generally made from carbon steel an additional coating for corrosion protection - mainly solvent-based polymers - is necessary. However, it is not enough to consider the selection and combination of the materials. Regarding the construction and manufacturing of corrosion-resistant drums for low- and medium-level radioactive waste there also has to be paid closer attention to the joining technologies such as welding. For lifetime prediction of low-/medium-level waste packages reliable experimental data concerning the long-term corrosion behaviour of each material as well as of the components is needed. Therefore sheet metals from carbon steel were galvanized or coated with different solvent-based and water-based corrosion protection materials (epoxy as well as silicone resins). After damaging the anti-corrosion coating of some of these sheets with predefined scratches sets of these samples were stored at higher temperatures in climatic chamber, in simulated waste or aged according to standard DIN EN ISO 9227. All corrosion damages were analyzed by means of metallography (light microscopy as well as scanning electron microscopy of micro-sections). The quantitative influence of the corrosive attacks on the mechanical properties of the materials was examined by mechanical testing according to DIN EN 10002. Besides reduction of tensile strength drastic reduction of percentage of elongation after fracture (from 30 % to 10 %) was found. Further experiments were carried out using components or scaled-down drums joined by means of innovative welding techniques such as Cold Arc or Force Arc. The relevant welding parameters (e.g. welding current, proper volume of shielding gas or wire feed) were

  8. Electrochemical Behaviour and Galvanic Effects of Titanium Implants Coupled to Metallic Suprastructures in Artificial Saliva

    Directory of Open Access Journals (Sweden)

    Ana Mellado-Valero

    2018-01-01

    Full Text Available The aim of the present study is to analyze the electrochemical behavior of five different dental alloys: two cobalt-chromium alloys (CoCr and CoCr-c, one nickel-chromium-titanium alloy (NiCrTi, one gold-palladium alloy (Au, and one titanium alloy (Ti6Al4V, and the galvanic effect when they are coupled to titanium implants (TiG2. It was carried out by electrochemical techniques (open circuit measurements, potentiodynamic curves and Zero-Resistance Ammetry in artificial saliva (AS, with and without fluorides in different acidic conditions. The studied alloys are spontaneously passivated, but NiCrTi alloy has a very narrow passive domain and losses its passivity in presence of fluorides, so is not considered as a good option for implant superstructures. Variations of pH from 6.5 to 3 in artificial saliva do not change the electrochemical behavior of Ti, Ti6Al4V, and CoCr alloys, and couples, but when the pH of the artificial saliva is below 3.5 and the fluoride content is 1000 ppm Ti and Ti6Al4V starts actively dissolving, and CoCr-c superstructures coupled to Ti show acceleration of corrosion due to galvanic effects. Thus, NiCrTi is not recommended for implant superstructures because of risk of Ni ion release to the body, and fluorides should be avoided in acidic media because Ti, Ti6Al4V, and CoCr-c superstructures show galvanic corrosion. The best combinations are Ti/Ti6Al4V and Ti/CoCr as alternative of noble gold alloys.

  9. Electrochemical Behaviour and Galvanic Effects of Titanium Implants Coupled to Metallic Suprastructures in Artificial Saliva

    Science.gov (United States)

    Mellado-Valero, Ana; Igual Muñoz, Anna; Guiñón Pina, Virginia

    2018-01-01

    The aim of the present study is to analyze the electrochemical behavior of five different dental alloys: two cobalt-chromium alloys (CoCr and CoCr-c), one nickel-chromium-titanium alloy (NiCrTi), one gold-palladium alloy (Au), and one titanium alloy (Ti6Al4V), and the galvanic effect when they are coupled to titanium implants (TiG2). It was carried out by electrochemical techniques (open circuit measurements, potentiodynamic curves and Zero-Resistance Ammetry) in artificial saliva (AS), with and without fluorides in different acidic conditions. The studied alloys are spontaneously passivated, but NiCrTi alloy has a very narrow passive domain and losses its passivity in presence of fluorides, so is not considered as a good option for implant superstructures. Variations of pH from 6.5 to 3 in artificial saliva do not change the electrochemical behavior of Ti, Ti6Al4V, and CoCr alloys, and couples, but when the pH of the artificial saliva is below 3.5 and the fluoride content is 1000 ppm Ti and Ti6Al4V starts actively dissolving, and CoCr-c superstructures coupled to Ti show acceleration of corrosion due to galvanic effects. Thus, NiCrTi is not recommended for implant superstructures because of risk of Ni ion release to the body, and fluorides should be avoided in acidic media because Ti, Ti6Al4V, and CoCr-c superstructures show galvanic corrosion. The best combinations are Ti/Ti6Al4V and Ti/CoCr as alternative of noble gold alloys. PMID:29361767

  10. Electrochemical corrosion and bioactivity of Ti-Nb-Sn-hydroxyapatite composites fabricated by pulse current activated sintering.

    Science.gov (United States)

    Xiaopeng, Wang; Fantao, Kong; Biqing, Han; Yuyong, Chen

    2017-11-01

    Ti-Nb-Sn-hydroxyapatite (HA) composites were prepared by mechanical alloying for different times (unmilled, 4, 8 and 12h), followed by pulse current activated sintering. The effects of the milling time on the electrochemical corrosion resistance and bioactivity of the sintered Ti-35Nb-2.5Sn-15HA composites were investigated. Potentiodynamic polarization test results indicated that the sintered Ti-35Nb-2.5Sn-15HA composites exhibited higher corrosion resistance with increasing milling time. The corrosion potential and current of the Ti-35Nb-2.5Sn-15HA composite sintered by 12h milled powders were - 0.261V and 0.18μA/cm 2 , respectively, and this sintered composite showed a stable and wide passivation region. The hemolysis rate of the sintered Ti-35Nb-2.5Sn-15HA composites reduced with increasing milling time and the lowest hemolytic rate of the composites was 0.87%. In addition, the in vitro cell culture results indicated that the composite sintered by 12h milled powders had good biocompatibility. These results indicate the significant potential of Ti-35Nb-2.5Sn/xHA composites for biomedical implant applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Photo-Electrochemical Effect of Zinc Addition on the Electrochemical Corrosion Potentials of Stainless Steels and Nickel Alloys in High Temperature Water

    International Nuclear Information System (INIS)

    Lee, Yi-Ching; Fong, Clinton; Fang-Chu, Charles; Chang, Ching

    2012-09-01

    Hydrogen water chemistry (HWC) is one of the main mitigating methods for stress corrosion cracking problem of reactor core stainless steel and nickel based alloy components. Zinc is added to minimize the radiation increase associated with HWC. However, the subsequently formed zinc-containing surface oxides may exhibit p-type semiconducting characteristics. Upon the irradiation of Cherenkov and Gamma ray in the reactor core, the ECP of stainless steels and nickel based alloys may shift in the anodic direction, possibly offsetting the beneficial effect of HWC. This study will evaluate the photo-electrochemical effect of Zinc Water Chemistry on SS304 stainless steel and Alloy 182 nickel based weld metal under simulated irradiated BWR water environments with UV illumination. The experimental results reveal that Alloy 182 nickel-based alloy generally possesses n-type semiconductor characteristics in both oxidizing NWC and reducing HWC conditions with zinc addition. Upon UV irradiation, the ECP of Alloy 182 will shift in the cathodic direction. In most conditions, SS304 will also exhibit n-type semiconducting properties. Only under hydrogen water chemistry, a weak p-type property may emerge. Only a slight upward shift in the anodic direction is detected when SS304 is illuminated with UV light. The potential influence of p-type semiconductor of zinc containing surface oxides is weak and the mitigation effect of HWC on the stress corrosion cracking is not adversely affected. (authors)

  12. Review of Artificial Neural Networks (ANN) applied to corrosion monitoring

    International Nuclear Information System (INIS)

    Mabbutt, S; Picton, P; Shaw, P; Black, S

    2012-01-01

    The assessment of corrosion within an engineering system often forms an important aspect of condition monitoring but it is a parameter that is inherently difficult to measure and predict. The electrochemical nature of the corrosion process allows precise measurements to be made. Advances in instruments, techniques and software have resulted in devices that can gather data and perform various analysis routines that provide parameters to identify corrosion type and corrosion rate. Although corrosion rates are important they are only useful where general or uniform corrosion dominates. However, pitting, inter-granular corrosion and environmentally assisted cracking (stress corrosion) are examples of corrosion mechanisms that can be dangerous and virtually invisible to the naked eye. Electrochemical noise (EN) monitoring is a very useful technique for detecting these types of corrosion and it is the only non-invasive electrochemical corrosion monitoring technique commonly available. Modern instrumentation is extremely sensitive to changes in the system and new experimental configurations for gathering EN data have been proven. In this paper the identification of localised corrosion by different data analysis routines has been reviewed. In particular the application of Artificial Neural Network (ANN) analysis to corrosion data is of key interest. In most instances data needs to be used with conventional theory to obtain meaningful information and relies on expert interpretation. Recently work has been carried out using artificial neural networks to investigate various types of corrosion data in attempts to predict corrosion behaviour with some success. This work aims to extend this earlier work to identify reliable electrochemical indicators of localised corrosion onset and propagation stages.

  13. Corrosion monitoring in a straw-fired power plant using an electrochemical noise probe

    DEFF Research Database (Denmark)

    Cappeln, Frederik Vilhelm; Bjerrum, Niels; Petrushina, Irina

    2007-01-01

    Electrochemical Noise Measurements have been carried out in situ in a straw-fired power plant using an experimental probe constructed from alumina and AlSl 347 steel. Based on a framework of controlled laboratory experiments it has been found that electrochemical noise has the unique ability to p...

  14. Corrosion behaviour of Al-Fe-Ti-V medium entropy alloy

    Science.gov (United States)

    Bodunrin, M. O.; Obadele, B. A.; Chown, L. H.; Olubambi, P. A.

    2017-12-01

    Alloys containing up to four multi-principal elements in equiatomic ratios are referred to as medium entropy alloys (MEA). These alloys have attracted the interest of many researchers due to the superior mechanical properties it offers over the traditional alloys. The design approach of MEA often results to simple solid solution with either body centered cubic; face centered cubic structures or both. As the consideration for introducing the alloys into several engineering application increases, there have been efforts to study the corrosion behaviour of these alloys. Previous reports have shown that some of these alloys are more susceptible to corrosion when compared with traditional alloys due to lack of protective passive film. In this research, we have developed AlFeTiV medium entropy alloys containing two elements (Ti and Al) that readily passivate when exposed to corrosive solutions. The alloys were produced in vacuum arc furnace purged with high purity argon. Open circuit potential and potentiodynamic polarisation tests were used to evaluate the corrosion behaviour of the as-cast AlFeTiV alloy in 3.5 wt% NaCl and 1 M H2SO4. The corrosion performance of the alloy was compared with Ti-6Al-4V alloy tested under similar conditions. The results show that unlike in Ti-6Al-4V alloy, the open circuit potential of the AlFeTiV alloy move towards the negative values in both 3.5 wt% NaCl and 1 M H2SO4 solutions indicating that self-activation occurred rapidly on immersion. Anodic polarisation of the alloys showed that AlFeTiV alloy exhibited a narrow range of passivity in both solutions. In addition, the alloys exhibited lower Ecorr and higher Icorr when compared with traditional Ti-6Al-4V alloy. The traditional Ti-6Al-4V alloy showed superior corrosion resistant to the AlFeTiV alloy in both 3.5 wt.% NaCl and 1 M H2SO4 solutions.

  15. Electrochemical methods for corrosion testing of Ce-based coating prepared on AA6060 alloy by dip immersion method

    Directory of Open Access Journals (Sweden)

    Jegdić Bore V.

    2013-01-01

    Full Text Available Dip-immersion is simple and cost-effective method for the preparation of Ce-based conversion coatings (CeCCs, a promising alternative to the toxic chromate coatings, on the metal substrates. In this work CeCCs were prepared on Al-alloy AA6060 from aqueous solution of cerium chloride at room temperature. Effect of immersion time and post-treatment in phosphate solution on the microstructure and corrosion properties of the coatings was studied. The longer immersion time, the thicker but nonhomogeneous and cracked CeCCs. The post-treatment contributed to the sealing of cracks, as proven by an increase in corrosion resistance compared with as-deposited coatings. CeCCs prepared at longer deposition time and post-treated showed much better corrosion protection than those prepared at short deposition time. A detailed EIS study was undertaken to follow the evolution of corrosion behaviour of CeCCs with time of exposure to aggressive chloride environment (3.5 % NaCl. For the sake of comparison, the EIS properties of bare AA6060 were also investigated. A linear voltammetry was performed to complete the study. Results confirmed a formation of protective CeCCs on AA6060 surface. However, even CeCCs prepared at longer deposition time and post-treated provided a short term protection in aggressive environment, due to the small thickness. [Projekat Ministarstva nauke Republike Srbije, br. III 45019 i br. III 45012

  16. Effect of cerium addition on corrosion behaviour of AZ61 + XCe alloy under salt spray test

    Directory of Open Access Journals (Sweden)

    S. Manivannan

    2016-03-01

    Full Text Available The corrosion behaviour of Mg–6Al–1Zn + XCe (where X = 0.5, 1.0, 1.5 and 2.0 wt% Ce alloys, aged for 18 h at different temperatures of 180 °C, 200 °C, 220 °C and 240 °C, was studied in 3.5 wt% NaCl solution. The salt spray test was conducted in accordance with ASTM-B117 standard (fog test. The corrosion morphologies, corrosion rate and the composition of the corrosion products were investigated by X-ray Diffraction (XRD, Optical Microscopy (OM and Scanning Electron Microscopy (SEM techniques. The results show the cerium addition and ageing treatment has significantly influenced the corrosion morphologies and the corrosion rate. In AZ61 alloy, the intermetallic β (Mg17Al12 phase acts as a corrosion barrier and upon ageing the Al4Ce phase precipitates along the α grain boundaries. The precipitation modifies the β phase to form more continuous network which subsequently reduces the corrosion attack in the chlorine environment. Salt spray test result shows the AZ61 alloy with 1.5 wt% Ce aged at 220 °C exhibits the better corrosion resistance.

  17. Corrosion behaviour of container materials for geological disposal of high-level waste. Joint annual progress report 1983

    International Nuclear Information System (INIS)

    1985-01-01

    Within the framework of the Community R and D programme on management and storage of radioactive waste (shared-cost action), a research activity is aiming at the assessment of corrosion behaviour of potential container materials for geological disposal of vitrified high-level wastes. In this report, the results obtained during the year 1983 are described. Research performed at the Studiecentrum voor Kernenergie/Centre d'Etudes de l'Energie Nucleaire (SCK/CEN) at Mol (B), concerns the corrosion behaviour in clay environments. The behaviour in salt is tested by the Kernforschungszentrum (KfK) at Karlsruhe (D). Corrosion behaviour in granitic environments is being examined by the Commissariat a l'Energie Atomique (CEA) at Fontenay-aux-Roses (F) and the Atomic Energy Research Establishment (AERE) at Harwell (UK); the first is concentrating on corrosion-resistant materials and the latter on corrosion-allowance materials. Finally, the Centre National de la Recherche Scientifique (CNRS) at Vitry (F) is examining the formation and behaviour of passive layers on the metal alloys in the various environments

  18. In situ synthesis, electrochemical and quantum chemical analysis of an amino acid-derived ionic liquid inhibitor for corrosion protection of mild steel in 1M HCl solution

    International Nuclear Information System (INIS)

    Kowsari, E.; Arman, S.Y.; Shahini, M.H.; Zandi, H.; Ehsani, A.; Naderi, R.; PourghasemiHanza, A.; Mehdipour, M.

    2016-01-01

    Highlights: • Electrochemical analysis of effectiveness of an amino acid-derived ionic liquid inhibitor. • Quantum chemical analysis of effectiveness of an amino acid-derived ionic liquid inhibitor. • Finding correlation between electrochemical analysis and quantum chemical analysis. - Abstract: In this study, an amino acid-derived ionic liquid inhibitor, namely tetra-n-butyl ammonium methioninate, was synthesized and the role this inhibitor for corrosion protection of mild steel exposed to 1.0 M HCl was investigated using electrochemical, quantum and surface analysis. By taking advantage of potentiodynamic polarization, the inhibitory action of tetra-n-butyl ammonium methioninate was found to be mainly mixed-type with dominant anodic inhibition. The effectiveness of the inhibitor was also indicated using electrochemical impedance spectroscopy (EIS). Moreover, to provide further insight into the mechanism of inhibition, electrochemical noise (EN) and quantum chemical calculations of the inhibitor were performed.

  19. An Electrochemical Investigation into the Corrosion Protection Properties of Coatings for the Active Metal Copper

    OpenAIRE

    Carragher, Ursula

    2013-01-01

    In the research presented in this thesis, corrosion protection films were synthesised and characterised. The films were based on polypyrrole (PPy) coatings doped with combinations of tartrate, oxalate and dodecylbenzene sulfonate (DBS) along with the incorporation of multiwalled carbon nanotubes (MWCNT), and viologen films adsorbed at copper. The corrosion protective properties of these films were studied and compared to the uncoated copper substrate. They were assessed and stu...

  20. Comparative electrochemical investigation of the effect of aging on corrosion of dental amalgam.

    Science.gov (United States)

    Amin, Wala M

    2007-01-01

    To investigate corrosion in dental amalgam and evaluate the effects of composition and long-term aging on the alloy's corrosion behavior. A sample of high-copper and low-copper formulations was employed. Corrosion tests were performed using a 3-electrode polarization cell. Anodic polarization curves were drawn, and the potential and the current density corresponding to the first anodic peak were registered. Scanning electron microscopy was performed, and the different metallurgical phases of the alloy's microstructure were examined and analyzed chemically using an energy-dispersive x-ray technique. The amalgams' corrosion behavior was evaluated at 1 week and after aging in a simulated oral environment for 6 months, 1 year, and 2 years. Data were analyzed using analysis of variance (ANOVA)Scheffe post hoc test at a .05 significance level. The potential values recorded by the high-copper amalgam were higher (P amalgam than in the high-copper alloy. For both formulations the potentials increased significantly (P amalgam. High-copper amalgam exhibited better resistance to corrosion than the low-copper alloy. Aging in a simulated oral environment improved corrosion behavior for both high- and low-copper amalgams.

  1. Effects of Alloying Elements (Cr, Mn) on Corrosion Properties of Carbon Steel in Synthetic Seawater

    International Nuclear Information System (INIS)

    Hyun, Youngmin; Kim, Heesan

    2016-01-01

    Effects of alloying elements, manganese and chromium, on corrosion resistance of carbon steel were examined using weight loss test and electrochemical tests (polarization test and electrochemical impedance spectroscopy (EIS)) in synthetic seawater at 60 ℃. The results from the weight loss test showed that chromium effectively improved corrosion resistance of carbon steel during the entire immersion time, but manganese improved corrosion resistance after the lowered corrosion resistance at the beginnings of immersion. Unlike the weight loss test, the electrochemical tests showed that the corrosion resistance did not increase with immersion time, in all the specimens. This disagreement is explained by the presence of rust involved in electrochemical reaction during electrochemical tests. The analysis of rust with transmission electron microscopy (TEM)−energy dispersive spectroscopy (EDS) showed that the amorphous-like rust layer located at the metal/rust interface with enriched alloying element (Cr, Mn) prevents diffusion of corrosive species into a metal/rust interface effectively, which leads to increased corrosion resistance. The initial corrosion behaviour is also affected by the rust types. In other words, manganese accelerated the formation of spinel oxides, negatively affecting corrosion resistance. Meanwhile, chromium accelerated the formation of goethite but impeded the formation of spinel oxides, positively affecting the corrosion resistance. From the above results, the corrosion resistance of steel is closely related with a rust type.

  2. Corrosion behaviour of Zircaloy 4 fuel cans for high burnup in EdF PWRs

    International Nuclear Information System (INIS)

    Blat, M.; Kerrec, O.; Bourgoin, J.; Vrignaud, E.; Amanrich, H.

    1994-01-01

    Uniform corrosion of fuel cladding could be a limitation for burn-up enhancement. First, the oxide thickness measured on fuel cladding for high burn-up has been compared to the prediction of the EDF code, CYRANO 2E. A comparative metallurgical characterization has been also performed on samples which were oxidized in pile and in autoclave. Then, laboratories studies have been launched for a better understanding of the corrosion mechanisms. A reflection was proposed on the two main theoretical concepts proposed for these mechanisms. Their kinetics could be controlled by transfers in liquid medium (electrolyte) or in solid medium (compact oxide). For the first topic, a nanoscopic characterization of the oxide is in progress, using Atomic Force Microscope. The first results are presented. In the second case, an electrochemical approach (impedance spectroscopy and voltametry) is developed in our laboratories. The obtained results could give some new keys in order to understand the influence of some parameters (alloys composition, coolant chemistry,...). (authors). 7 figs., 1 tab., 7 refs

  3. Electrochemical studies of sodium meta-vanadate as corrosion inhibitor of carbon steel 1020 in CO{sub 2} and H{sub 2}S saturated DEA solutions

    Energy Technology Data Exchange (ETDEWEB)

    Aghasadeghi, Alireza [Corrosion Department of Research Institute of Petroleum Industry, P.O.Box 18745-4163, NIOC Pazhouheshgah Blvd., Khairabad, Qom Road, Tehran (Iran)

    2004-07-01

    Several types of corrosion inhibitors are recently used in amine systems for natural gas refining in the world because of the corrosive nature of amine solutions containing acid gases. This article introduces corrosion inhibitor basis that are used mostly as active reagents in corrosion inhibitor packages. Accordingly, sodium meta-vanadate is studied as corrosion inhibitor of carbon steel 1020 in 30-vol% DEA and industrial lean and rich amines solutions saturated with CO{sub 2} and H{sub 2}S at 65 deg. C. Electrochemical Tafel polarization test method was conducted to investigate the inhibitive behavior of sodium meta-vanadate in the mentioned solutions that are near industrial conditions. Tafel slopes and corrosion potentials show that the inhibitive mechanism of sodium meta-vanadate is anodic and effective dosage of the inhibitor is within 0.03 to 0.05 wt% in 30-vol% DEA, industrial lean and rich amines solutions saturated with CO{sub 2} and H{sub 2}S at 65 deg. C. Surface observations indicate that the corrosion on the carbon steel coupons was general and using this optimum concentration with an inhibitive performance of at least 80% did not occur localized or pitting corrosion. (author)

  4. An electrochemical investigation of the corrosion behavior of aluminum alloys in chloride containing solutions; Investigacao eletroquimica da corrosao de ligas de aluminio em solucoes contendo cloretos

    Energy Technology Data Exchange (ETDEWEB)

    Campos Filho, Jorge Eustaquio de [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Escola de Engenharia. Dept. de Engenharia Quimica]. E-mail: jorgecamposfilho@yahoo.com.br; Neves, Celia de Figueiredo Cordeiro; Campos, Wagner Reis da Costa; Moreira, Marcilio Soares [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)]. E-mail: caf@cdtn.br; wrcc@cdtn.br; msm@cdtn.br

    2005-07-01

    Aluminum alloys have been used as cladding materials for nuclear fuel in research reactors due to its corrosion resistance. Aluminum owes its good corrosion resistance to a protective barrier oxide film formed and strongly bonded to its surface. In pool type TRIGA IPR-R1 reactor, located at Centro de Desenvolvimento da Tecnologia Nuclear in Belo Horizonte, previous immersion coupon tests revealed that aluminum alloys suffer from pitting corrosion, in spite of high quality of water control. Corrosion attack is initiated by breaking the protective oxide film on aluminum alloy surface. Chloride ions can break this oxide film and stimulate metal dissolution. In this study the aluminum alloys 1050, 5052 and 6061 were used to evaluate their corrosion behavior in chloride containing solutions. The electrochemical techniques used were potentiodynamic anodic polarization and cyclic polarization. Results showed that aluminum alloys 5052 and 6061 present similar corrosion resistance in low chloride solutions (0,1 ppm NaCl) and in reactor water but both alloys are less resistant in high chloride solution (1 ppm NaCl). Aluminum alloy 1050 presented similar behavior in the three electrolytes used, regarding to pitting corrosion, indicating that the concentration of the chloride ions was not the only variable to influence its corrosion susceptibility. (author)

  5. Corrosion and alteration of materials from the nuclear industry

    International Nuclear Information System (INIS)

    Beauvy, M.; Berthoud, G.; Defranceschi, M.; Ducros, G.; Feron, D.; Guerin, Y.; Latge, C.; Limoge, Y.; Madic, C.; Santarini, G.; Seiler, J.M.; Vernaz, E.; Richet, C.

    2010-01-01

    , testing means, experimental techniques, internal corrosion of zircaloy sheath - the iodine effect, stress corrosion of nickel alloys - hydrogen influence, stress corrosion of stainless steels; C - wear corrosion: a coupled phenomenon, research in the framework of service life extension of the French electronuclear park; 3 - Corrosion in future reactors: A - corrosion in gas reactors: corrosion by helium impurities, oxidation resistance of silicon carbide, corrosion of graphite and carbon-carbon composites; B - corrosion in liquid metal reactors: sodium FBRs, lead and lead alloys reactors; C- corrosion in molten salt reactors: corrosion of Hastelloy N-type nickel alloys by molten fluorides, mass transfer in aniso-thermal fluoride systems, tellurium embrittlement, electrochemical study of pure metals corrosion in molten fluorides; 4 - Materials corrosion and alteration in the back-end of the fuel cycle: A - corrosion in concentrated nitric environment: materials behaviour, self-catalytic mechanism of nitric acid reduction; B - corrosion in unsaturated aqueous environment: metallic corrosion in unsaturated environment - application to the storage of waste containers, bitumens alteration, reinforced concrete behaviour and iron framework corrosion, concrete behaviour in severe thermal environment; C - Corrosion in saturated aqueous environment: metals corrosion in clayey environment, long-term behaviour of glasses, ceramics alteration, underwater concrete durability, clays transformation; D - materials biodegradation: microorganisms and nuclear wastes, biodegradation of bitumen, concretes and steels; 5 - Conclusion, glossary

  6. Electrochemical and corrosion behavior of two chromium dental alloys in artificial bioenvironments

    Directory of Open Access Journals (Sweden)

    Banu Alexandra

    2017-01-01

    Full Text Available The purpose of this study is to compare the corrosion and tarnish behavior of NiCrMo and CoCrMo cast dental alloys in artificial bio environments. The cobalt chromium alloys are known and used in dentistry for many years, but its difficult machinability because of the strength and hardness, is an argument for scientists to study alternative materials with comparable biocompatibility. On the other hand, for dentistry devices beside corrosion behavior is important the aesthetic so, the used alloys have to preserve their shining and do not stain. The corrosion resistance has been evaluated using the Atomic mass spectroscopy method for ion release determination, the anodic polarization curves and the open circuit potential – time monitoring for corrosion behavior evaluation and optical microscopy for the structure analysis. The tarnish tendency of alloys was estimated using the method of cyclic immersion with frequency of 10 seconds for each minute during 72 hours in Na2S containing solution. The most important conclusion is that the alloys are comparable from corrosion and tarnish point of view, but we recommend to use the nickel base alloy only for orthodontic devices implanted for short periods of time, because of higher quantity of released ions.

  7. Computational and electrochemical investigation for corrosion inhibition of nickel in molar sulfuric acid by dihydrazide derivatives. Part II

    Directory of Open Access Journals (Sweden)

    H. Shokry

    2017-05-01

    Full Text Available Correlation of the efficiency of some dihydrazide derivatives, namely malonic acid (MAD, succinic acid (SAD and adipic acid (AAD dihydrazide, against the corrosion of nickel in 1 M sulfuric acid solution is discussed using electrochemical polarization method and quantum chemical calculations based on the ab initio method. The quantum chemical parameters calculated are, the highest occupied molecular orbital (HOMO, the lowest unoccupied molecular orbital (LUMO, the gap energy (ΔE, the dipole moment (μ, the softness (σ and the total energy (TE. The relations between the inhibition efficiency and some quantum parameters are discussed and correlations are proposed. The protection efficiencies of these compounds showed a certain relationship to Mulliken atomic charges and Fukui indices. Dihydrazide inhibitor (AAD exhibited the highest inhibition efficiency.

  8. Dental amalgam - the effect of the technology of alloy powder preparation on the corrosion behaviour and the release of mercury

    Energy Technology Data Exchange (ETDEWEB)

    Joska, L.; Bystriansky, J.; Novak, P. [Institute of Chemical Technology, Prague, Institute of Metals and Corrosion Engineering, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2003-03-01

    Dental amalgams are based on a broad spectrum of materials differing in their chemical composition, metallurgical treatment, and in the way the initial alloys powders are prepared. In addition to their chemical composition, amalgams based on various powders differ in both their microstructure and the amount of mercury needed for preparation. All these facts may affect electrochemical processes occurring during their interaction with oral fluids, and also mercury release. While verifying the effect of the technology used for the preparation of the high-copper ternary alloy powder on the properties of resulting amalgams, this study aimed at the mechanism of their interaction with a model saliva solution as well as mercury release was included. Measurements were done in a model saliva solution using standard electrochemical methods and exposition measurements. The interaction of individual types of amalgams with artificial saliva did not reveal any significant differences. The free corrosion potential of all these amalgams in an aerated solution settled in the range of values in which tin oxidation, resulting in a layer of insoluble corrosion products, turned out to be the dominant anodic process. The rate of mercury release was the lowest for amalgams based on a gas-atomized alloy. The highest rate of mercury release, and also its dependence on time, was exhibited by lathe-cut powder based amalgam. In addition to different volume fraction of the Ag-Hg phase and the level of its tin alloying, this different behaviour may be explained by differences in the rate at which a layer of tin corrosion products acting as a barrier to mercury release is formed. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Dentalamalgame basieren auf einem breitem Spektrum von Werkstoffen, die sich in ihrer chemischen Zusammensetzung, der metallurgischen Behandlung und der Art, wie die Ausgangslegierungspulver hergestellt werden, unterscheiden. Zusaetzlich zu ihrer chemischen

  9. Electrochemical behaviour and nanoscale characteristics of CNT-based fibers as new substrate for cell growth

    Energy Technology Data Exchange (ETDEWEB)

    Polizu, S.; Yahia, L.H. [Ecole Polytechnique de Montreal, PQ (Canada). Laboratoire d' innovation et d' analyse de la bioperformance; Savadogo, O. [Ecole Polytechnique de Montreal, Montreal, PQ (Canada). Laboratoire de nouveaux materiaux pour l' energie et l' electrochimie; Maugey, M.; Poulin, P. [Centre de Recherche Paul Pascal, CNRS, Bordeaux (France); Rouabhia, M. [Laval Univ., Quebec City, PQ (Canada). Faculty of Medicine

    2008-07-01

    This paper reported on a study in which carbon nanotube (CNT) macroscopic fibers were formulated by a newly developed non-covalent method for fabricating fibrous substrate. The covalent and noncovalent chemistry of CNTs has been widely used in the development of CNT-based biomaterials as active substrates for living cells. Time of Flight Mass Spectroscopy (TOF-SIMS) analysis was used to determine the surface characteristics of the CNT-based fibers produced by wet spinning method. The structure and texture of fibers were imaged using Low-Vacuum Scanning Electron Microscopy (LV-SEM) equipped with an Energy Dispersive Spectrometer (EDS) for microanalysis. Atomic Force Microscopy (AFM) imaging revealed the structure of fibers. Cyclic Voltametry (CV) measurements were performed to examine the electrochemical behaviour of fibers. Sulfuric acid and a cell culture medium was used as the 2 different electrolytes. The influences of environmental parameters on the electrochemical phenomena taking place were identified. The intrinsic electrochemical characteristics of fibers were revealed through measurements in acid environment. The cell culture medium simulated the physiological conditions. It was concluded that the newly developed wet spinning method is very efficient for making CNT-based fibers as electroactive biomaterials. The structural nanoscale details evidenced a good alignment of nanotubes in the thread and the critical role it plays in electrochemical interactions. The differences induced by the variation of electrolytes suggest that a relationship could be established between the fiber chemistry and the electrochemical response. This correlation has considerably potential for the design of new biomedical devices. 2 refs.

  10. Electrochemical Studies of Corrosion in Liquid Electrolytes for Energy Conversion Applications at Elevated Temperatures

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey Valerievich; Petrushina, Irina; Bjerrum, Niels J.

    2016-01-01

    Stainless steels (AISI 316, 321 and 347), high-nickel alloys (Hasteloy®C-276 and Inconel®625), tantalum, nickel, titanium, tungsten, molybdenum, niobium, platinum, and gold were tested for corrosion resistance in molten KH2PO4 (or KH2PO4-K2H2P2O7) as a promising electrolyte for the intermediate......-temperature (200–400°C) water electrolysis. Pt, Ta, Nb, Ti, Inconel®625, and Ni demonstrated high corrosion resistance. Au and the rest of the tested materials were not corrosion resistant. It means that Ni, Ti and Inconel®625 may be used as relatively cheap construction materials for the intermediate...

  11. An electrochemical investigation of the corrosion behavior of Al-Si-Cu hypereutectic alloys in alcoholic environments

    Directory of Open Access Journals (Sweden)

    Traldi, S. M.

    2003-12-01

    Full Text Available Al-Si-Cu hypereutetic alloys produced by spray forming are mostly used in the automotive industry, especially for cylinder liners. They have the advantage of low weight associated with low coefficient of thermal expansion and excellent mechanical properties - mainly wear resistance at high temperatures. The corrosion resistance of these alloys in fuels, particularly alcoholic media, however is not yet known. In this investigation, electrochemical impedance spectroscopy (EIS and potentiodynamic polarisation have been used to evaluate the corrosion resistance of a hypereutectic Al-Si-Cu alloy in alcoholic environments. The EIS tests were carried out in pure ethanol, and ethanol with small additions (1 mM of acid and chloride, to investigate the effect of these contaminants on corrosion resistance. The corrosion resistance of a grey cast iron has also been evaluated in pure ethanol for comparison. The Al-Si-Cu alloy showed high corrosion resistance in pure ethanol, far superior to that of grey cast iron in the same medium.

    Aleaciones hipereutécticas producidas por conformación por spray son muy empleadas en la industria automovilística, especialmente en los revestimientos de los cilindros. Tienen la ventaja de añadir menos peso con bajo coeficiente de expansión térmica y excelentes propiedades mecánicas, sobre todo resistencia al desgaste en altas temperaturas. Todavía, la resistencia a la corrosión de estas aleaciones en combustibles no es conocida. En este estudio fueron utilizadas las técnicas de espectroscopia de impedancia electroquímica y polarización potenciodinámica, para evaluar la resistencia a la corrosión de una aleación hipereutéctica Al-Si-Cu en medio alcohólico. Las pruebas fueron conducidas en etanol puro y etanol con pequeñas adiciones (1 mM de ácido y cloruro, con la finalidad de investigar el efecto de estos contaminantes en la resistencia a la corrosión. Hierro fundido gris, también fue

  12. Prediction of Long Term Corrosion Behaviour in Nuclear Waste Systems. Proceedings of an International Workshop, Cadarache, France, 2002

    International Nuclear Information System (INIS)

    Feron, Damien; Macdonald, Digby D.

    2003-01-01

    This 36. book of the European Federation of Corrosion series contains the proceedings of the International Workshop on 'Prediction of Long Term Corrosion Behaviour in Nuclear Waste Systems' that took place in Cadarache, France in November 2001. The EFC Working Party on Nuclear Corrosion, which sponsored this Workshop, had already considered in 1991 that the long term integrity of Radioactive Waste storage was a crucial problem in the development of nuclear energy for electricity production. At that time, it was realized that public opinion on Nuclear Energy, was concerned not only with the risk of a nuclear accidents but also with the safety of long term storage of high level nuclear wastes. The nuclear community and the public demanded that any technical barrier for preventing long term radionuclides from entering the biosphere should be effective and guaranteed for 10,000 or more. The integrity of the waste containers, particularly their resistance to possible internal and external corrosion, is the most important aspect of this requirement. For the last ten years, the importance of programmes on long term corrosion on nuclear waste canisters has become of major significance to the international community. The Cadarache Workshop included reports on these programmes from eight countries. These approached the long term corrosion tests, but also by the development of the necessary deterministic and empirical models for extrapolating the behaviour of the selected materials. The difficulties involved in developing such models of corrosion behaviour and in demonstrating their validity has been underlined many times. The Proceedings contains in all an Introduction by Professor G. Beranger and 33 papers grouped in four parts as follows: 1 - R and D corrosion programmes (5 papers); 2 - Laboratory and in situ testing (11 papers); 3 - Historical and archaeological analogues (5 papers); and 4 - Fundamental issues, models and prediction

  13. Development of Advanced Electrochemical Emission Spectroscopy for Monitoring Corrosion in Simulated DOE Liquid Waste

    Energy Technology Data Exchange (ETDEWEB)

    MacDonal, Digby D.; Marx, Brian M.; Ahn, Sejin; Ruiz, Julio de; Soundararajan, Balaji; Smith, Morgan; Coulson, Wendy

    2005-06-15

    Various forms of general and localized corrosion represent principal threats to the integrity of DOE liquid waste storage tanks. These tanks, which are of a single wall or double wall design, depending upon their age, are fabricated from welded carbon steel and contain a complex waste-form comprised of NaOH and NaNO3, along with trace amounts of phosphate, sulfate, carbonate, and chloride. Because waste leakage can have a profound environmental impact, considerable interest exists in predicting the accumulation of corrosion damage, so as to more effectively schedule maintenance and repair.

  14. In-situ electrochemical-AFM study of localized corrosion of AlxCoCrFeNi high-entropy alloys in chloride solution

    Science.gov (United States)

    Shi, Yunzhu; Collins, Liam; Balke, Nina; Liaw, Peter K.; Yang, Bin

    2018-05-01

    In-situ electrochemical (EC)-AFM is employed to investigate the localized corrosion of the AlxCoCrFeNi high-entropy alloys (HEAs). Surface topography changes on the micro/sub-micro scale are monitored at different applied anodizing potentials in a 3.5 wt% NaCl solution. The microstructural evolutions with the increased Al content in the alloys are characterized by SEM, TEM, EDS and EBSD. The results show that by increasing the Al content, the microstructure changes from single solid-solution to multi-phases, leading to the segregations of elements. Due to the microstructural variations in the AlxCoCrFeNi HEAs, localized corrosion processes in different ways after the breakdown of the passive film, which changes from pitting to phase boundary corrosion. The XPS results indicate that an increased Al content in the alloys/phases corresponds to a decreased corrosion resistance of the surface passive film.

  15. Irradiation-assisted stress corrosion cracking[1997 Scientific Report of the Belgian Nuclear Research Centre

    Energy Technology Data Exchange (ETDEWEB)

    Moons, F.

    1998-07-01

    The programme on corrosion at the Belgian Nuclear Research Centre SCK-CEN started in 1996 and focusses on modelling irradiation-assisted stress corrosion cracking and on developing in-pile electrochemical sensors and diagnostic equipment. The objective of this programme is to predict the behaviour of LWR core internals with respect to IASCC. Progress for 1997 is summarised.

  16. Electrochemical behaviour of PES ionomer and Pt-free catalyst for PEMFCs

    Directory of Open Access Journals (Sweden)

    STEFANIA GIORDANO

    2013-06-01

    Full Text Available Proton Exchange Membrane Fuel Cells (PEMFCs represent promising technologies to the world economy, with many applications and low environmental impact. A most important aspect concerning their widespread implementation is the cost of polymeric membranes, typically perfluorinated membranes and platinum-based catalytic electrode materials, all of which are necessary to promote electrode reactions, thus increasing fuel cell energy efficiency. In this work, we present some data about non-fluorinated polyetheresulphone (PES membranes and Pt-free catalysts, as possible substitutes of the above materials. Their electrochemical behaviour in oxygen reduction reaction in acidic media are investigated and compared with available reference materials.

  17. Some aspects of the electrochemical behaviour of mild steel in carbonate/bicarbonate solutions

    International Nuclear Information System (INIS)

    Rangel, C.M.; Leitao, R.A.; Fonseca, I.T.

    1986-01-01

    The electrochemical behaviour of mild steel in aqueous solutions of sodium carbonate/sodium bicarbonate (600 ppm) has been investigated using potentiodynamic polarization. In the pre-passive region three well-defined peaks are observed associated to reduction peaks corresponding to Fe(II) and Fe(III) species. A transpassive anodic peak is also observed being attributed to Fe(VI) species showing, in sweep reversal experiments, an associated reduction peak and an increase in the peak associated to the reduction of Fe(III) species. The characterization of the transpassive peak will be subject of further publication. (author)

  18. Electrochemical and quantum chemical studies of some indole derivatives as corrosion inhibitors for C38 steel in molar hydrochloric acid

    Energy Technology Data Exchange (ETDEWEB)

    Lebrini, M. [Laboratoire Materiaux et Molecules en Milieu Amazonien, CNRS 8172-UMR ECOFOG, Campus Trou Biran, Cayenne 97337, French Guiana (France); Robert, F. [Laboratoire Materiaux et Molecules en Milieu Amazonien, UAG-UMR ECOFOG, Campus Trou Biran, Cayenne 97337, French Guiana (France); Vezin, H. [Laboratoire de Chimie Organique et Macromoleculaire, UMR-CNRS 8009, USTL BatC4 F-59655 Villeneuve d' Ascq Cedex (France); Roos, C., E-mail: christophe.roos@guyane.univ-ag.f [Laboratoire Materiaux et Molecules en Milieu Amazonien, UAG-UMR ECOFOG, Campus Trou Biran, Cayenne 97337, French Guiana (France)

    2010-10-15

    A comparative study of 9H-pyrido[3,4-b]indole (norharmane) and 1-methyl-9H-pyrido[3,4-b]indole (harmane) as inhibitors for C38 steel corrosion in 1 M HCl solution at 25 {sup o}C was carried out. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behavior in the absence and presence of different concentrations of these inhibitors. The OCP as a function of time were also established. Cathodic and anodic polarization curves show that norharmane and harmane are a mixed-type inhibitors. Adsorption of indole derivatives on the C38 steel surface, in 1 M HCl solution, follows the Langmuir adsorption isotherm model. The {Delta}G{sub ads}{sup o} values were calculated and discussed. The potential of zero charge (PZC) of the C38 steel in inhibited solution was studied by the EIS method, and a mechanism for the adsorption process was proposed. Raman spectroscopy confirmed that indole molecules strongly adsorbed onto the steel surface. The electronic properties of indole derivates, obtained using the AM1 semi-empirical quantum chemical approach, were correlated with their experimental efficiencies using the linear resistance model (LR).

  19. Electrochemical and quantum chemical study of purines as corrosion inhibitors for mild steel in 1 M HCl solution

    International Nuclear Information System (INIS)

    Yan Ying; Li Weihua; Cai Lankun; Hou Baorong

    2008-01-01

    The purines and its derivatives, such as, guanine, adenine, 2,6-diaminopurine, 6-thioguanine and 2,6-dithiopurine, were investigated as corrosion inhibitors for mild steel in 1 M HCl solution by weight loss measurements, electrochemical tests and quantum chemical calculations. The polarization curves of mild steel in the hydrochloric acid solutions of the purines showed that both cathodic and anodic processes of steel corrosion were suppressed. The Nyquist plots of impedance expressed mainly as a depressed capacitive loop with different compounds and concentrations. For all these purines, the inhibition efficiency increased by increasing the inhibitor concentration, and the inhibition efficiency orders are 2,6-dithiopurine > 6-thioguanine > 2,6-diaminopurine > adenine > guanine with the highest inhibiting efficiency of 88.0% for 10 -3 M 2,6-dithiopurine. The optimized structures of purines, the Mulliken charges, molecular orbital densities and relevant parameters were calculated by quantum chemical calculations. The quantum chemical calculation results inferred that the adsorption belong to physical adsorption, which might arise from the π stacking between the π electron of the purines and the metal surface

  20. Effect of Dissolved Oxygen and Immersion Time on the Corrosion Behaviour of Mild Steel in Bicarbonate/Chloride Solution

    Directory of Open Access Journals (Sweden)

    Gaius Debi Eyu

    2016-09-01

    Full Text Available The electrochemical behavior of mild steel in bicarbonate solution at different dissolved oxygen (DO concentrations and immersion times has been studied under dynamic conditions using electrochemical techniques. The results show that both DO and immersion times influence the morphology of the corrosion products. In comparative tests, the corrosion rate was systematically found to be lower in solutions with lower DO, lower HCO3− concentrations and longer immersion time. The SEM analyses reveal that the iron dissolution rate was more severe in solutions containing higher DO. The decrease in corrosion rate can be attributed to the formation of a passive layer containing mainly α -FeO (OH and ( γ -Fe2O3/Fe3O4 as confirmed by the X-ray diffractometry (XRD and X-ray photoelectron spectroscopy (XPS. Passivation of mild steel is evident in electrochemical test at ≈ −600 mVSCE at pH ≥ 8 in dearated ( ≤ 0.8 ppm DO chloride bicarbonate solution under dynamic conditions.

  1. Electrochemical impedance study on the corrosion of Al-Pure in ...

    Indian Academy of Sciences (India)

    processes and inhibit corrosion by blocking the reaction sites. The high inhibition efficiency of (A) and (B) were due to the adsorption of inhibitor molecules on the metal surface. The decrease of surface area available for electrode reactions to take place is due to the formation of a protective film. Activation energy and free ...

  2. The electrochemical deposition of tin-nickel alloys and the corrosion properties of the coating

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Møller, Per

    2005-01-01

    electrodeposition. The alloy has unique corrosion properties and exhibits surface passivation like stainless steel. The coating is decorative and non-allergic to the skin, can replace decorative nickel and nickel-chromium coatings in many cases and decreases the risk for allergic contact dermatitis. A number...

  3. Corrosion Behaviour of Heat - Treated Al-6063/ SiCp Composites Immersed in 5 wt% NaCl Solution

    Directory of Open Access Journals (Sweden)

    Kenneth ALANEME

    2011-06-01

    Full Text Available The influence of SiC volume percent and temper conditions (namely, as-cast, solutionized, and artificial age hardening at 180°C and 195°C on the corrosion behaviour of Al (6063 composites and its monolithic alloy immersed in 5wt% NaCl solution has been investigated. Al (6063 - SiC particulate composites containing 6, 12 and 15 volume percent SiC were produced by premixing the SiC particles with borax additive and then adopting two step stir casting. Mass loss and corrosion rate measurements were utilized as criteria for evaluating the corrosion behaviour of the composites. The results show that the corrosion susceptibility of the Al (6063 - SiCp composites was higher than that of the monolithic alloy, and for most cases the corrosion rate of the composites increased with increase in volume percent of SiC. However, it was discovered that the nature of the passive films formed on the composites was sufficiently stable to reduce significantly the corrosion rate of the composites after 13days of immersion. This trend was observed to be consistent for all heat-treatment conditions utilized.

  4. Comparative corrosion study of Ag–Pd and Co–Cr alloys used in ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The electrochemical behaviour of two Ag–Pd alloys (Unique White and Paliag) used in dental prosthetics construction for crowns and bridges and one Co–Cr alloy (Vitallium 2000) was studied in artificial saliva using the polarization curves and electrochemical impedance spectroscopy (EIS). The corrosion resi-.

  5. Comparative corrosion study of Ag–Pd and Co–Cr alloys used in ...

    Indian Academy of Sciences (India)

    The electrochemical behaviour of two Ag–Pd alloys (Unique White and Paliag) used in dental prosthetics construction for crowns and bridges and one Co–Cr alloy (Vitallium 2000) was studied in artificial saliva using the polarization curves and electrochemical impedance spectroscopy (EIS). The corrosion resistance was ...

  6. In-vitro long term and electrochemical corrosion resistance of cold deformed nitrogen containing austenitic stainless steels in simulated body fluid.

    Science.gov (United States)

    Talha, Mohd; Behera, C K; Sinha, O P

    2014-07-01

    This work was focused on the evaluation of the corrosion behavior of deformed (10% and 20% cold work) and annealed (at 1050 °C for 15 min followed by water quenching) Ni-free high nitrogen austenitic stainless steels (HNSs) in simulated body fluid at 37°C using weight loss method (long term), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Scanning electron microscopy (SEM) was used to understand the surface morphology of the alloys after polarization test. It has been observed that cold working had a significant influence on the corrosion resistant properties of these alloys. The weight loss and corrosion rates were observed to decrease with increasing degree of cold working and nitrogen content in the alloy. The corrosion resistance of the material is directly related to the resistance of the passive oxide film formed on its surface which was enhanced with cold working and nitrogen content. It was also observed that corrosion current densities were decreased and corrosion potentials were shifted to more positive values. By seeing pit morphology under SEM, shallower and smaller pits were associated with HNSs and cold worked samples, indicating that corrosion resistance increases with increasing nitrogen content and degree of cold deformation. X-ray diffraction profiles of annealed as well as deformed alloys were revealed and there is no evidence for formation of martensite or any other secondary phases. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Study by acoustic emission and electrochemical methods of the corrosion and the protection of the copper-zinc alloy (60/40) in neutral and alkaline media

    International Nuclear Information System (INIS)

    Assouli, B.

    2002-12-01

    The aim of this work is to study and characterize, by electrochemical methods and acoustic emission, the corrosion and the protection of the copper-zinc alloy (60/40) having a metallographic structure αβ'. The electrochemical measurements, in neutral, chlorinated or alkaline medium have allowed, to study the corrosion resistance of the copper-zinc and to show that the corrosion of this alloy, in the used media, is determined by a diffusional mechanism. The observations to the optical and scanning electron microscopes and the EDX analyzes have confirmed that this corrosion phenomenon is mainly due to the selective dissolution of the β' phase. The acoustic emission has shown, during this corrosion, the presence of two emissive sources whose initiation has been attributed to the relaxation of the micro- and macro- residual stresses of the α phase. These stresses have been characterized by X-ray diffraction and the salvoes emitted during the relaxation of these stresses have been discriminated by the characteristic frequencies and by the barycenter of their spectral density. The protection of this alloy has been carried out by the 2-mercapto-benzimidazole (MBI). This last compound has been tested both as inhibitor added directly in the corrosive medium and/or as polymer film previously deposited by an electrochemical way (p-MBI). The MBI is very efficient for an inhibition in a chlorinated alkaline medium. It is an interphase inhibitor. The p-MBI is efficient too in a neutral chlorinated medium and is moreover non pollutant for the environment. (O.M.)

  8. Electrochemical study of bio-corrosion mechanisms at the carbon steel interface in presence of iron-reducing and hydrogenotrophic bacteria in the nuclear waste disposal context

    International Nuclear Information System (INIS)

    Leite-de-Souza-Moreira, Rebeca

    2013-01-01

    The safety of deep geological repository for nuclear waste is a very important and topical matter especially for the nuclear industry. Such as nuclear fuel the high level waste have to be stored for time frames of millions of years in metallic containers. Typically these containers should be placed in deep geological clay formations 500 metres underground. Corrosion processes, will take place after the re-saturation of the geological medium and under the prevalent anoxic conditions may lead to the generation of hydrogen. This gas accumulates in clay environment through the years and eventually becomes hazardous for steel containers. In the particular environment of geological repositories does not provide much biodegradable substances. This is the reason that hydrogen represents a new suitable energy source for hydrogenotrophic bacteria. Thereby formed bacterial bio-films on the containers may contribute to a process of fast decay of the steel, the so called bio-corrosion. The aim of this study is to characterize the electrochemical interfaces in order to obtain the mechanisms of bio-corrosion of carbon steels in presence of iron reducing and hydrogenotrophic bacterium Shewanella oneideinsis. The products of corrosion processes, namely hydrogen and iron (III) oxides are used as electron donor and acceptor, respectively. The amount of hydrogen consumed by Shewanella could be estimated with 10 -4 mol s -1 using Scanning Electrochemical Microscopy (SECM) techniques. The influence of the local hydrogen generation was evaluated via chrono-amperometry. When hydrogen was locally generated above a carbon steel substrate an accelerated corrosion process can be observed. Eventually, using Local Electrochemical Impedance Spectroscopy (LEIS) techniques, the mechanism of the generalised corrosion process was demonstrated. (author)

  9. Effect of Ca(OH)2, NaCl, and Na2SO4 on the corrosion and electrochemical behavior of rebar

    Science.gov (United States)

    Jin, Zuquan; Zhao, Xia; Zhao, Tiejun; Hou, Baorong; Liu, Ying

    2017-05-01

    The corrosion of rebar in reinforced concrete in marine environments causes significant damage to structures built in ocean environments. Studies on the process and mechanism of corrosion of rebar in the presence of multiple ions may help to control damage and predict the service life of reinforced concrete structures in such environments. The effect of interactions between sulfate and chloride ions and calcium hydroxide on the electrochemical behavior of rebar are also important for evaluation of structure durability. In this work, electrochemical impedance spectroscopy (EIS) plots of rebar in Ca(OH)2 solution and cement grout, including NaCl and Na2SO4 as aggressive salts, were measured for diff erent immersion times. The results show that corrosion of rebar was controlled by the rate of charge transfer as the rebar was exposed to chloride solution. In the presence of high concentrations of sulfate ions in the electrolyte, generation and dissolution of the passive film proceeded simultaneously and corrosion was mainly controlled by the diff usion rate. When Na2SO4 and NaCl were added to Ca(OH)2 solution, the instantaneous corrosion rate decreased by a factor of 10 to 20 as a result of the higher pH of the corroding solution.

  10. Electrochemical Study on Corrosion Inhibition of Copper in Hydrochloric Acid Medium and the Rotating Ring-Disc Voltammetry for Studying the Dissolution

    Directory of Open Access Journals (Sweden)

    A. K. Satpati

    2011-01-01

    Full Text Available Dissolution characteristics of copper in hydrochloric acid medium and the effect of 4-amino 1,2,4-triazole (ATA on the corrosion process have been studied using conventional electrochemical techniques and rotating ring-disc electrodes (RRDEs. Corrosion potential (corr and corrosion current density (corr were obtained by Tafel extrapolation methods. Charge transfer resistance (ct and double-layer capacitance (dl were obtained from the electrochemical impedance spectroscopy (EIS. ATA was shown to be an effective inhibitor for the copper-corrosion inhibition in acid medium. The corrosion rate was retarded in presence of inhibitors mainly because of the adsorption of the inhibitor on the electrode surface. Adsorption of the inhibitor on the metal surface was found to follow the Langmuir adsorption isotherm. Standard free energy change of the adsorption process (Δ0ad was calculated to be −54.3 kJ mol−1; such a large negative value of Δ0ad suggests the prescence of a chemisorption process.

  11. Corrosion effect on the electrochemical properties of LaNi3.55Mn0.4Al0.3Co0.75 and LaNi3.55Mn0.4Al0.3Fe0.75 negative electrodes used in Ni-MH batteries

    International Nuclear Information System (INIS)

    Khaldi, Chokri; Boussami, Sami; Rejeb, Borhene Ben; Mathlouthi, Hamadi; Lamloumi, Jilani

    2010-01-01

    The thermodynamic parameters, electrochemical capacity, equilibrium potential and the equilibrium pressure, of LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 and LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 alloys have been evaluated from the electrochemical isotherms (C/30 and OCV methods) and CV technique. A comparative study has been done between the parameter values deduced from the electrochemical methods and the solid-gas method. The parameter values deduced from the electrochemical methods are influenced by the electrochemical corrosion of the alloys in aqueous KOH electrolyte. The corrosion behaviour of the LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 and LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 electrodes after activation was investigated using the method of the potentiodynamic polarization. The variation of current and potential corrosion values with the state of charge (SOC) show that the substitution of cobalt by iron accentuates the corrosion process. The high-rate dischargeability (HRD) of the LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 and LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 alloys was examined. By increasing the discharge current the (HRD) decrease linearly for both the alloys and for the LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 compound is greater then for the LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 one.

  12. Corrosion behaviour of sintered Ti–Ni–Cu–Nb in 0.9% NaCl environment

    Directory of Open Access Journals (Sweden)

    Moipone Linda Lethabane

    2015-10-01

    Full Text Available The uniform and localized corrosion behaviour of sintered Ti–Ni containing niobium and copper additions were studied using potentiodynamic and cyclic polarization measurements in 0.9% sodium chloride. Results indicated that copper and niobium addition did not have significant effects on the uniform corrosion characteristics, but significantly improved the pitting corrosion resistance. Both copper and niobium additions significantly increased the re-passivation potentials, while copper was observed to reduce the pitting hysteresis loop area. Alloys containing 15% copper and 2% niobium additions depicted the most improved pitting corrosion resistance, and increased the re-passivation value from −315.60 mV to a high re-passivation potential of 840.68 mV.

  13. Electrochemical corrosion studies on copper-base waste package container materials in unirradiated 0.1 N NaNO3 at 95 degrees C

    International Nuclear Information System (INIS)

    Akkaya, M.; Verink, E.D. Jr.; Van Konynenburg, R.A.

    1988-05-01

    Three candidate materials were investigated in this study in terms of their electrochemical corrosion behavior in unirradiated 0.1 N NaNO 3 solutions at 95 degrees C. Anodic polarization experiments were conducted to determine the passive current densities, pitting potentials, and other parameters, together with Cyclic Current Reversal Voltammetry tests to evaluate the stability and protectiveness of the passive oxides formed. X-ray diffraction and Auger Electron Spectroscopy were used for identification of the corrosion products as well as Scanning Electron Microscopy for the surface morphology studies. 2 refs., 22 figs., 2 tabs

  14. An Electrochemical Framework to Explain Intergranular Stress Corrosion Cracking in an Al-5.4%Cu-0.5%Mg-0.5%Ag Alloy

    Science.gov (United States)

    Little, D. A.; Connolly, B. J.; Scully, J. R.

    2001-01-01

    A modified version of the Cu-depletion electrochemical framework was used to explain the metallurgical factor creating intergranular stress corrosion cracking susceptibility in an aged Al-Cu-Mg-Ag alloy, C416. This framework was also used to explain the increased resistance to intergranular stress corrosion cracking in the overaged temper. Susceptibility in the under aged and T8 condition is consistent with the grain boundary Cu-depletion mechanism. Improvements in resistance of the T8+ thermal exposure of 5000 h at 225 F (T8+) compared to the T8 condition can be explained by depletion of Cu from solid solution.

  15. Evaluation of the protection behaviour of reinforcement steel against corrosion induced by chlorides in reinforced mortar specimens

    International Nuclear Information System (INIS)

    Crivelaro, Marcos

    2002-01-01

    drying for 5 days. The corrosion tests used in this investigation were gravimetric and electrochemical tests. The results showed satisfactory corrosion performance for all kinds of protection measures. However, the performance depended on the type of protection used. The best performance was obtained with tannin containing epoxy coated steel, followed by the steel treated by immersion in tannin containing solutions and finally by the addition of tannin (Black Wattle) or lignin to the mortar. All the protection measures evaluated in this study are economically viable and environmentally friendly and can therefore be considered for protecting reinforcement steels against corrosion. (author)

  16. Electrochemical Processes

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers

    1997-01-01

    The notes describe in detail primary and secondary galvanic cells, fuel cells, electrochemical synthesis and electroplating processes, corrosion: measurments, inhibitors, cathodic and anodic protection, details of metal dissolution reactions, Pourbaix diagrams and purification of waste water from...... galvanic industries....

  17. Study of niobium corrosion in alkaline medium

    International Nuclear Information System (INIS)

    Almeida, S.H. de.

    1987-01-01

    A comparative study of niobium electrochemical behaviour in NaOH and KOH solution, with concentrations between 0,5 and 6,1M is presented. The studies were done through electrochemicals assays, consisting in the corrosion potential and anodic and cathodic polarization curves, complemented by loss of mass experiments. The niobium anodic behaviour in alkaline medium is characterized by passivation occurrence, with a stable film formation. The Na oH solution in alkaline medium are more corrosible to niobium than the KOH solution. The loss of mass assays showed that the corrosion velocit is more dependente of hydroxide concentration in KOH medium than the NaOH medium. (C.G.C.) [pt

  18. Effect of nitrogen ion implantation on in vitro corrosion behaviour of NiTi

    Directory of Open Access Journals (Sweden)

    Barcos, R.

    2008-08-01

    Full Text Available In the last decade, different surface modifications have been developed to enhance the biocompatibility of NiTi shape memory alloys. The present paper deals with the influence of nitrogen ion implantation on corrosion behavior of NiTi in Hank’s solution. Nitrogen implantation at 150 keV with nominal doses ranged from 0.5x1017 to 8x1017 ion cm–2, were used. Mechanical surface characterization was carried out by nanohardness, corrosion mechanism evaluation by electrochemical polarization and impedance spectroscopy (EIS tests and surface composition by XPS spectra. The results point out the benefit of the N-implanted for corrosion resistance at a suitable dose 2x1017 ion cm-2 and an increase of the mechanical properties with the doses.

    Durante la pasada década se han empleado diferentes técnicas de modificación superficial para mejorar la biocompatibilidad de la aleación de NiTi con memoria de forma. Este trabajo se centra en el estudio de la influencia del N implantado con una energía de 150 keV y con dosis nominales comprendidas entre 0.5x1017 to 8x1017 ion cm–2, en el comportamiento frente a la corrosión del NiTi en solución de Hank. Se han realizado medidas de nanodurezas y de resistencia a la corrosión mediante curvas de polarización potencio-dinámicas y espectroscopía de impedancia electroquímica, así como los cambios en composición promovidos en la superficie se evaluaron mediante XPS. Los resultados de dichos ensayos revelaron una mejora en la resistencia a corrosión del comportamiento para las muestras implantadas con una dosis de N de 2x10–17 ion•cm–2 y un aumento de la nanodureza y de la rigidez superficial con la dosis implantada

  19. Corrosion behaviour of the AlSi6Cu4 alloy and cast AlSi6Cu4-graphite particles composite

    Directory of Open Access Journals (Sweden)

    S. Holecek

    2009-04-01

    Full Text Available The corrosion behaviour of the AlSi6Cu4 alloy as a composite matrix and of composites with 8% vol. of graphite particles was investigated. The corrosion experiments were performed over a range of elevated temperatures and were carried out in sea water (3.5%NaCl solution. We have focused our attention to the determination of the mode of corrosion attack and to the determination of the rate ofcorrosion and other corrosion characteristics. Both as-cast and annealed matrix and composite specimens were tested, as well as the99.9% as-cast aluminium for comparison. Corrosion behaviour of the materials was assessed by the corrosion potential (Ec and bypotentiodynamic (polarization curves. As expected, composite is less corrosion resistant than the matrix alloy. In addition to pitting,a severe galvanic corrosion occurs as a result of galvanic couple aluminium/graphite formation. Corrosion potentials imply that examinedmaterials would be sufficiently resistant in non or slightly oxidizing solutions without dissolved oxygen. All studied materials corrode very slowly at potentials negative to corrosion potential, while at potentials positive to corrosion potential the corrosion rate goes up by 1 or 2 orders.

  20. 3D study of intermetallics and their effect on the corrosion morphology of rheocast aluminium alloy

    International Nuclear Information System (INIS)

    Mingo, B.; Arrabal, R.; Pardo, A.; Matykina, E.; Skeldon, P.

    2016-01-01

    In the present study, the effect of heat treatment T6.1 on the microstructure and corrosion behaviour of rheocast aluminium alloy A356 is investigated on the basis of 2D/3D characterization techniques and electrochemical and SKPFM measurements. Heat treatment strengthens the α-Al matrix, modifies the intermetallic particles and spheroidizes eutectic Si. These changes do not modify significantly the corrosion behaviour of the alloy. 3D SEM-Tomography clearly shows that the corrosion advances in the shape of narrow paths between closely spaced intermetallics without a major influence of eutectic Si. - Highlights: • T6.1 spheroidizes Si, strengthens the matrix and modifies the intermetallics. • Electrochemical behaviour of untreated and heat-treated alloys is similar. • 3D SEM-Tomography provides additional information on the corrosion morphology. • Corrosion advances as paths between intermetallics with little influence of Si.

  1. Development of Self-Powered Wireless-Ready High Temperature Electrochemical Sensors for In-Situ Corrosion Monitoring for Boiler Tubes in Next Generation Coal-based Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xingbo [West Virginia Univ., Morgantown, WV (United States)

    2015-06-30

    The key innovation of this project is the synergy of the high temperature sensor technology based on the science of electrochemical measurement and state-of-the-art wireless communication technology. A novel self-powered wireless high temperature electrochemical sensor system has been developed for coal-fired boilers used for power generation. An initial prototype of the in-situ sensor demonstrated the capability of the wireless communication system in the laboratory and in a pilot plant (Industrial USC Boiler Setting) environment to acquire electrochemical potential and current signals during the corrosion process. Uniform and localized under-coal ash deposit corrosion behavior of Inconel 740 superalloy has been studied at different simulated coal ash hot corrosion environments using the developed sensor. Two typical potential noise patterns were found to correlate with the oxidation and sulfidation stages in the hot coal ash corrosion process. Two characteristic current noise patterns indicate the extent of the corrosion. There was a good correlation between the responses of electrochemical test data and the results from corroded surface analysis. Wireless electrochemical potential and current noise signals from a simulated coal ash hot corrosion process were concurrently transmitted and recorded. The results from the performance evaluation of the sensor confirm a high accuracy in the thermodynamic and kinetic response represented by the electrochemical noise and impedance test data.

  2. Automated Methods Of Corrosion Measurements

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers; Andersen, Jens Enevold Thaulov; Reeve, John Ch

    1997-01-01

    The chapter describes the following automated measurements: Corrosion Measurements by Titration, Imaging Corrosion by Scanning Probe Microscopy, Critical Pitting Temperature and Application of the Electrochemical Hydrogen Permeation Cell.......The chapter describes the following automated measurements: Corrosion Measurements by Titration, Imaging Corrosion by Scanning Probe Microscopy, Critical Pitting Temperature and Application of the Electrochemical Hydrogen Permeation Cell....

  3. Corrosion and tarnish of dental silver-based alloys in 0.1% Na2S and Ringer's solutions. (Part 1) Electrochemical study.

    Science.gov (United States)

    Endo, K; Araki, Y; Ohno, H

    1989-06-01

    The corrosion behavior of three silver-based alloys, Ag-Sn-Zn, Ag-In, and Ag-Pd-Cu, were investigated by potentiodynamic anodic polarization analysis and the polarization resistance method in 0.1% Na2S and Ringer's solutions. The corrosion activity of the Ag-Sn-Zn alloy was higher in Ringer's solution than in the 0.1% Na2S solution. In contrast, the corrosion rate of the Ag-Pd-Cu alloy was approximately 500 times higher in the 0.1% Na2S solution than in Ringer's solution. The results show that the generally accepted concept that tarnish is merely a surface discoloration due to the deposition of insoluble products is inadequate. The alloy discolors while being severely attacked in the presence of sulfides. For the Ag-In alloy, the corrosion activity in the 0.1% Na2S solution was as high as in Ringer's solution. These silver-based alloys exhibit different electrochemical activities in different solutions. The test solutions for corrosion tests must be carefully chosen for each alloy system through a screening test to replicate the predominant corrosion reaction proceeding in the oral environment.

  4. Study of electrochemical corrosion characteristics of Inconel alloys with addition of trace elements

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sung Goon; Park, In Ho; Lee, Sang Hoon [Hanyang University, Seoul (Korea)

    2002-04-01

    Inconel alloys which have high temperature mechanical properties and corrosion resistance have been used extensively as steam generator tube of nuclear power plants. But, since environments of steam generator are high temperature and pressure, there have been many reports of the damage cases of steam generators which are made with Inconel 600. The failure through corrosion of steam generator's parts made with Inconel alloy became generally known because of IGSCC result from Cr depletion zone. Therefore, the development of materials added element which obstructs formation of Cr depletion zone on grainboundary were imminent, we intended to investigate the effects on known prevention and different prevention mechanism of corrosion according to added amount of Nb known as proper inhibitor against SCC. Specimens used to experiment were divided into heat treatment(SA and SA SEN) and added amount of Nb(0, 2, 4, 6%), when DL-EPR Tests (measurement of degree of sensitization were executed, composition of electrolyte is aqueous solution mixed 0.5M H2SO4 and 5ppm KSCN , electrolytes were aqueous solution mixed 10% NaOH on potentiodynamic and potentiostatic tests at RT and high temperature. As a result of experiment, degree of sensitization of SA heat treated specimens was lower than that of SA SEN heat treated specimens. According to added Nb, degree of sensitization of specimens over 2% Nb were similar. There is no particularly different experimental results through added element, heat treatment on potentiondynamic and potentiostatic experiments at RT and high temperature. Although heat treatment and added amount of Nb affected a little degree of grainboundary sensitization, these experimental factors didn't have effects on forming the passive film. 13 refs., 19 figs. (Author)

  5. In vitro degradation and electrochemical corrosion evaluations of microarc oxidized pure Mg, Mg-Ca and Mg-Ca-Zn alloys for biomedical applications.

    Science.gov (United States)

    Pan, Yaokun; He, Siyu; Wang, Diangang; Huang, Danlan; Zheng, Tingting; Wang, Siqi; Dong, Pan; Chen, Chuanzhong

    2015-02-01

    Calcium phosphate (CaP) ceramic coatings were fabricated on pure magnesium (Mg) and self-designed Mg-0.6Ca, Mg-0.55Ca-1.74Zn alloys by microarc oxidation (MAO). The coating formation, growth and biomineralization mechanisms were discussed. The coating degradability and bioactivity were evaluated by immersion tests in trishydroxymethyl-aminomethane hydrochloric acid (Tris-HCl) buffer and simulated body fluid (SBF) solutions, respectively. The coatings and corrosion products were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS) and fourier transform infrared spectrometer (FT-IR). The electrochemical workstation was used to investigate the electrochemical corrosion behaviors of substrates and coatings. Results showed that Mg-0.55Ca-1.74Zn alloy exhibits the highest mechanical strength and electrochemical corrosion resistance among the three alloys. The MAO-coated Mg-0.55Ca-1.74Zn alloy has the potential to be served as a biodegradable implant. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Effect of nitrogen alloying of stainless steels on their corrosion stability

    International Nuclear Information System (INIS)

    Chigal, V.; Knyazheva, V.M.; Pitter, Ya.; Babich, S.G.; Bogolyubskij, S.D.

    1986-01-01

    Results of corrosion tests and structural investigations of 03Cr18Ni10 and 03Cr18Ni10Mo3 steels without nitrogen and with nitrogen content of 0.15-0.3% are presented. Corrosion-electrochemical behaviour of Cr20Ni20 steel with ultralow carbon content (0.004-0.006%) and nitrogen content with 0-0.5% as well as Cr 2 N nitride behaviour are investigated. A conclusion is made on nitrogen and excessive nitride phase effect on corrosion stability of steel in corrosive media with different reduction-oxidation properties

  7. Evaluation of the Synergistic Effect of Erosion-Corrosion on AISI 4330 Steel in Saline-Sand Multiphase Flow by Electrochemical and Gravimetric Techniques

    Directory of Open Access Journals (Sweden)

    Dario Yesid Peña Ballesteros

    2016-01-01

    Full Text Available The synergistic effects of fluid flow, sand particles, and solution pH on erosion-corrosion of AISI 4330 steel alloy in saline-sand medium were studied through a rotating cylinder electrode (RCE system by weight-loss and electrochemical measurements. The worn surface was analyzed by X-ray diffraction (XRD and scanning electron microscopy (SEM. Results show that, under all the test conditions assessed, the passivity of the steel alloy could not be maintained; as a result, an activation mechanism dominates the corrosion process of steel alloy. Furthermore, the potentiodynamic curves show that, with the increasing of the electrode flow rate and particle size, the anodic current density increased, which is due to deterioration of the electrode by the impacting slurry. Although the increase of particle size affects the anodic current density, the effect of particle size does not cause a significant change in the polarization behavior of the steel electrode. The electrochemical impedance and potentiodynamic curves suggest that erosion-corrosion phenomenon of the ASISI 4330 steel is under mixed control of mass transport and charge transfer. The inductive loops formed in the impedance plots are representative of an increase in roughness of the electrode caused by the particles impacting at the surface. The change in the passivity of the steel alloy as the pH is altered plays an important role in the corrosion rate.

  8. Electrochemical studies on stress corrosion cracking of incoloy-800 in caustic solution. Part II: Precracking samples

    Directory of Open Access Journals (Sweden)

    Dinu Alice

    2006-01-01

    Full Text Available Stress corrosion cracking (SCC in a caustic medium may affect the secondary circuit tubing of a CANDU NPP cooled with river water, due to an accidental formation of a concentrated alkaline environment in the areas with restricted circulation, as a result of a leakage of cooling water from the condenser. To evaluate the susceptibility of Incoloy-800 (used to manufacture steam generator tubes for CANDU NPP to SCC, some accelerated corrosion tests were conducted in an alkaline solution (10% NaOH, pH = 13. These experiments were performed at ambient temperature and 85 °C. We used the potentiodynamic method and the potentiostatic method, simultaneously monitoring the variation of the open circuit potential during a time period (E corr/time curve. The C-ring method was used to stress the samples. In order to create stress concentrations, mechanical precracks with a depth of 100 or 250 μm were made on the outer side of the C-rings. Experimental results showed that the stressed samples were more susceptible to SCC than the unstressed samples whereas the increase in temperature and crack depth lead to an increase in SCC susceptibility. Incipient micro cracks of a depth of 30 μm were detected in the area of the highest peak of the mechanical precrack.

  9. Mitigation of Intergranular Stress Corrosion Cracking in Al-Mg by Electrochemical Potential Control

    Science.gov (United States)

    McMahon, M. E.; Scully, J. R.; Burns, J. T.

    2017-08-01

    Intergranular stress corrosion cracking in the Al-Mg alloy AA5456-H116 is suppressed via cathodic polarization in 0.6 M NaCl, saturated (5.45 M) NaCl, 2 M MgCl2, and saturated (5 M) MgCl2. Three zones of intergranular stress corrosion cracking (IG-SCC) susceptibility correlate with pitting potentials of unsensitized AA5456-H116 and pure β phase (Al3Mg2) in each solution. These critical potentials reasonably describe the influence of α Al matrix and β phase dissolution rates on IG-SCC severity. Complete inhibition occurred at applied potentials of -1.0 V and -1.1 V versus saturated calomel electrode ( V SCE) in 0.6 M NaCl. Whereas only partial mitigation of IG-SCC was achieved at -0.9 V SCE in 0.6 M NaCl and at -0.9, -1.0, and -1.1 V SCE in the more aggressive environments. Correlation of pitting potentials in bulk environments with IG-SCC behavior suggests an effect of bulk environment [Cl-] and pH on the stabilized crack tip chemistry.

  10. TRANSITIONS IN ELECTROCHEMICAL NOISE DURING PITTING CORROSION OF ALUMINUM IN CHLORIDE ENVIRONMENTS.

    Energy Technology Data Exchange (ETDEWEB)

    SASAKI,K.; ISAACS,H.S.; LEVY,P.W.

    2001-09-02

    Aluminum, in a chloride containing solutions close to its pitting potential, shows vigorous fluctuations in current and potential. Measurements have been made of the freely corroding potential, and the currents between interconnected electrodes. It is shown that there is a transition in the behavior of the transients. The transition occurs when multiple active pits are present and electrochemical communication occurs between them. The major source of current and potential transients is the growth process in the active pits rather than meta-stable pitting at the passive surface.

  11. ECLSS Sustaining Metal Materials Compatibility Final Report, Electrochemical and Crevice Corrosion Test Results

    Science.gov (United States)

    Lee, R. E.

    2015-01-01

    Electrochemical test results are presented for six noble metals evaluated in two acidic test solutions which are representative of waste liquids processed in the Environmental Control and Life Support System (ECLSS) aboard the International Space Station (ISS). The two test solutions consisted of fresh waste liquid which had been modified with a proposed or alternate pretreatment formulation and its associated brine concentrate. The six test metals included three titanium grades, (Commercially Pure, 6Al-4V alloy and 6Al-4V Low Interstitial alloy), two nickel-chromium alloys (Inconel® 625 and Hastelloy® C276), and one high tier stainless steel (Cronidur® 30).

  12. Electrochemical corrosion behavior and elasticity properties of Ti-6Al-xFe alloys for biomedical applications.

    Science.gov (United States)

    Lu, Jinwen; Zhao, Yongqing; Niu, Hongzhi; Zhang, Yusheng; Du, Yuzhou; Zhang, Wei; Huo, Wangtu

    2016-05-01

    The present study is to investigate the microstructural characteristics, electrochemical corrosion behavior and elasticity properties of Ti-6Al-xFe alloys with Fe addition for biomedical application, and Ti-6Al-4V alloy with two-phase (α+β) microstructure is also studied as a comparison. Microstructural characterization reveals that the phase and crystal structure are sensitive to the Fe content. Ti-6Al alloy displays feather-like hexagonal α phase, and Ti-6Al-1Fe exhibits coarse lath structure of hexagonal α phase and a small amount of β phase. Ti-6Al-2Fe and Ti-6Al-4Fe alloys are dominated by elongated, equiaxed α phase and retained β phase, but the size of α phase particle in Ti-6Al-4Fe alloy is much smaller than that in Ti-6Al-2Fe alloy. The corrosion resistance of these alloys is determined in SBF solution at 37 °C. It is found that the alloys spontaneously form a passive oxide film on their surface after immersion for 500 s, and then they are stable for polarizations up to 0 VSCE. In comparison with Ti-6Al and Ti-6Al-4V alloys, Ti-6Al-xFe alloys exhibit better corrosion resistance with lower anodic current densities, larger polarization resistances and higher open-circuit potentials. The passive layers show stable characteristics, and the wide frequency ranges displaying capacitive characteristics occur for high iron contents. Elasticity experiments are performed to evaluate the elasticity property at room temperature. Ti-6Al-4Fe alloy has the lowest Young's modulus (112 GPa) and exhibits the highest strength/modulus ratios as large as 8.6, which is similar to that of c.p. Ti (8.5). These characteristics of Ti-6Al-xFe alloys form the basis of a great potential to be used as biomedical implantation materials. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Electrochemical Corrosion and In Vitro Bioactivity of Nano-Grained Biomedical Ti-20Nb-13Zr Alloy in a Simulated Body Fluid

    Directory of Open Access Journals (Sweden)

    Mohamed A. Hussein

    2017-12-01

    Full Text Available The bioactivity and the corrosion protection for a novel nano-grained Ti-20Nb-13Zr at % alloy were examined in a simulated body fluid (SBF. The effect of the SPS’s temperature on the corrosion performance was investigated. The phases and microstructural details of the developed alloy were analyzed by XRD (X-ray Diffraction, SEM (Scanning Electron Microscopy, and TEM (Transmission Electron Microscope. The electrochemical study was investigated using linear potentiodynamic polarization and electrochemical impedance spectroscopy in a SBF, and the bioactivity was examined by immersing the developed alloy in a SBF for 3, 7, and 14 days. The morphology of the depositions after immersion was examined using SEM. Alloy surface analysis after immersion in the SBF was characterized by XPS (X-ray Photoelectron Spectroscopy. The results of the bioactivity test in SBF revealed the growth of a hydroxyapatite layer on the surface of the alloy. The analysis of XPS showed the formation of protective oxides of TiO2, Ti2O3, ZrO2, Nb2O5, and a Ca3(PO42 compound (precursor of hydroxyapatite deposited on the alloy surface, indicating that the presented alloy can stimulate bone formation. The corrosion resistance increased by increasing the sintering temperature and the highest corrosion resistance was obtained at 1200 °C. The improved corrosion protection was found to be related to the alloy densification. The bioactivity and the corrosion resistance of the developed nanostructured alloy in a SBF renders the nanostructured Ti-20Nb-13Zr alloy a promising candidate as an implant material.

  14. Electrochemical Corrosion and In Vitro Bioactivity of Nano-Grained Biomedical Ti-20Nb-13Zr Alloy in a Simulated Body Fluid.

    Science.gov (United States)

    Hussein, Mohamed A; Kumar, Madhan; Drew, Robin; Al-Aqeeli, Nasser

    2017-12-27

    The bioactivity and the corrosion protection for a novel nano-grained Ti-20Nb-13Zr at % alloy were examined in a simulated body fluid (SBF). The effect of the SPS's temperature on the corrosion performance was investigated. The phases and microstructural details of the developed alloy were analyzed by XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy), and TEM (Transmission Electron Microscope). The electrochemical study was investigated using linear potentiodynamic polarization and electrochemical impedance spectroscopy in a SBF, and the bioactivity was examined by immersing the developed alloy in a SBF for 3, 7, and 14 days. The morphology of the depositions after immersion was examined using SEM. Alloy surface analysis after immersion in the SBF was characterized by XPS (X-ray Photoelectron Spectroscopy). The results of the bioactivity test in SBF revealed the growth of a hydroxyapatite layer on the surface of the alloy. The analysis of XPS showed the formation of protective oxides of TiO₂, Ti₂O₃, ZrO₂, Nb₂O₅, and a Ca₃(PO₄)₂ compound (precursor of hydroxyapatite) deposited on the alloy surface, indicating that the presented alloy can stimulate bone formation. The corrosion resistance increased by increasing the sintering temperature and the highest corrosion resistance was obtained at 1200 °C. The improved corrosion protection was found to be related to the alloy densification. The bioactivity and the corrosion resistance of the developed nanostructured alloy in a SBF renders the nanostructured Ti-20Nb-13Zr alloy a promising candidate as an implant material.

  15. Electrochemical behaviour of dysprosium in the eutectic LiCl-KCl at W and Al electrodes

    International Nuclear Information System (INIS)

    Castrillejo, Y.; Bermejo, M.R.; Barrado, A.I.; Pardo, R.; Barrado, E.; Martinez, A.M.

    2005-01-01

    The electrochemical behaviour of DyCl 3 was studied in the eutectic LiCl-KCl at different temperatures. The cathodic reaction can be written:Dy(III)+3e-bar Dy(0)which can be divided in two very close cathodic steps:Dy(III)+1e-bar Dy(II)andDy(II)+2e-bar Dy(0)Transient electrochemical techniques, such as cyclic voltammetry, chronopotentiometry, and chronoamperometry were used in order to study the reaction mechanism and the transport parameters of electroactive species at a tungsten electrode. The results showed that in the eutectic LiCl-KCl, electrocrystallization of dysprosium seems to be the controlling electrochemical step. Chronoamperometric studies indicated instantaneous nucleation of dysprosium with three dimensional growth of the nuclei whatever the applied overpotential.Mass transport towards the electrode is a simple diffusion process, and the diffusion coefficient of the electroactive species, i.e. Dy(III), has been calculated. The validity of the Arrhenius law was also verified by plotting the variation of the logarithm of the diffusion coefficient versus 1/T.In addition, the electrode reactions of the LiCl-KCl-DyCl 3 solutions at an Al wire were also investigated by cyclic voltammetry and open circuit chronopotentiometry. The redox potential of the Dy(III)/Dy couple at the Al electrode was observed at more positive potentials values than those at the inert electrode. This potential shift was thermodynamically analyzed by a lowering of activity of Dy in the metal phase due to the formation of intermetallic compounds

  16. Inhibition Behaviour of Some Isonicotinic Acid Hydrazides on the Corrosion of Mild Steel in Hydrochloric Acid Solution

    Directory of Open Access Journals (Sweden)

    M. P. Chakravarthy

    2013-01-01

    Full Text Available New corrosion inhibitors, namely, isonicotinic acid (1H-indol-3-yl-methylenehydrazide (INIMH and isonicotinic acid (1H-pyrrol-2-yl-methylenehydrazide (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.

  17. The role of solidification rate in the corrosion resistance of a directionally solidified novel aluminium-lanthanum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dzib-Perez, L. [Programa de Corrosion del Golfo de Mexico, Universidad Autonoma de Campeche, Av. Agustin Melgar s/n, Col. Buenavista, CP 24030 Campeche, Campeche (Mexico); Gonzalez-Sanchez, J. [Programa de Corrosion del Golfo de Mexico, Universidad Autonoma de Campeche, Av. Agustin Melgar s/n, Col. Buenavista, CP 24030 Campeche, Campeche (Mexico)]. E-mail: jagonzal@uacam.mx; Perez, T. [Programa de Corrosion del Golfo de Mexico, Universidad Autonoma de Campeche, Av. Agustin Melgar s/n, Col. Buenavista, CP 24030 Campeche, Campeche (Mexico); Bartolo-Perez, P. [Programa de Corrosion del Golfo de Mexico, Universidad Autonoma de Campeche, Av. Agustin Melgar s/n, Col. Buenavista, CP 24030 Campeche, Campeche (Mexico); CINVESTAV-Merida, Applied Physics Department, Carr. antigua a Progreso, km 6, CP 97310 Merida, Yucatan (Mexico); Juarez, A. [CIATEQ. Calzada del Retablo 150, CP 76150 Queretaro, Queretaro (Mexico)

    2006-08-15

    The corrosion resistance of a novel Al-12.6 wt.%La alloy manufactured using unidirectional solidification was studied by sensitive electrochemical techniques. It was found that the electrochemical behaviour of the alloy depends upon the formation of non-passive corrosion product layers. Different solidification rates produced dissimilar microstructures which promoted selective dissolution when the alloy was anodically polarized in distilled water. A model for the electrochemical behaviour of this alloy was proposed based on an equivalent circuit that simulated the impedance results.

  18. Microstructure and corrosion behaviour of gas tungsten arc welds of maraging steel

    Directory of Open Access Journals (Sweden)

    G. Madhusudhan Reddy

    2015-03-01

    Full Text Available Superior properties of maraging steels make them suitable for the fabrication of components used for military applications like missile covering, rocket motor casing and ship hulls. Welding is the main process for fabrication of these components, while the maraging steels can be fusion welded using gas tungsten arc welding (GTAW process. All these fabricated components require longer storage life and a major problem in welds is susceptible to stress corrosion cracking (SCC. The present study is aimed at studying the SCC behaviour of MDN 250 (18% Ni steel and its welds with respect to microstructural changes. In the present study, 5.2 mm thick sheets made of MDN 250 steel in the solution annealed condition was welded using GTAW process. Post-weld heat treatments of direct ageing (480 °C for 3 h, solutionizing (815 °C for 1 h followed by ageing and homogenizing (1150 °C for 1 h followed by ageing were carried out. A mixture of martensite and austenite was observed in the microstructure of the fusion zone of solutionized and direct aged welds and only martensite in as-welded condition. Homogenization and ageing treatment have eliminated reverted austenite and elemental segregation. Homogenized welds also exhibited a marginal improvement in the corrosion resistance compared to those in the as-welded, solutionized and aged condition. Constant load SCC test data clearly revealed that the failure time of homogenized weld is much longer compared to other post weld treatments, and the homogenization treatment is recommended to improve the SCC life of GTA welds of MDN 250 Maraging steel.

  19. Corrosion behaviour of the welded steel sheets used in automotive industry

    OpenAIRE

    D. Katundi; A. Tosun-Bayraktar; E. Bayraktar; D. Toueix

    2010-01-01

    Purpose: of this paper is to characterise the corrosion resistance in the steel sheets (Hot dip galvanizing of steel sheets) used in automotive industry. In fact, corrosion of automotive components by road salt is a widely known problem. The different parts under the car body and the interior surface of body panels suffer easily from the corrosive products deposited on roads and used mainly to melt snow. A comparison in a chemical investigation of the corrosion rate for base metals (without w...

  20. Effect of TiN particulate reinforcement on corrosive behaviour of ...

    Indian Academy of Sciences (India)

    Polarization studies indicate an increase in the corrosion resistance in composites compared to the matrix alloy. EIS study reveals that the polarization resistance (p) increases with increase in TiN content in composites, thus confirming improved corrosion resistance in composites. The observed decrease in corrosion rate ...

  1. Effect of chromium on the corrosion behaviour of powder-processed ...

    Indian Academy of Sciences (India)

    The studies compare electrolytic Armco iron with Fe–P alloys. It was observed that, chromium improved the resistance to corrosion in acidic and marine environments. The corrosion rates were minimal in alkaline medium and low in neutral solution. Keywords. Iron-phosphorous alloys; corrosion; powder metallurgy; forged;.

  2. Effect of TiN particulate reinforcement on corrosive behaviour of ...

    Indian Academy of Sciences (India)

    6061 alloy. It is understood that after the initiation of corrosion, interfacial corrosion products may have decoupled the conducting ceramic TiN from Al 6061 matrix alloy thus eliminating the galvanic effect between them. Keywords. Composites; corrosion; SEM; EDX; EIS. 1. Introduction. Particulate-reinforced aluminium metal ...

  3. Approach to corrosion mechanisms for a carbon steel in a solution of sodium chloride at 3 pc and its inhibition by means of organic molecules. Compared benefit of the use of stationary and transient electrochemical methods

    International Nuclear Information System (INIS)

    Duprat, Michel

    1981-01-01

    Within the context of an increased use of seawater as coolant in various industrial installations, this research thesis had two main objectives: the search for inhibitor organic compounds with optimal efficiency, and a better understanding of the mechanisms of corrosion inhibition by the best compounds within the considered organic compounds. After having reported a bibliographical study on carbon steel corrosion in seawater or in a sodium chloride solution at 3 pc, and on the inhibition of this corrosion, the author presents the experimental conditions (materials and methods). He reports the use of stationary and un-stationary electrochemical methods for the study of the steel-solution interface without inhibitor in order to get a better knowledge of corrosion electrochemical processes and to determine more precisely the corrosion rate. The last part addresses the study of the same interface but in presence of various inhibitors

  4. Investigation of the electrochemical behaviour of thermally prepared Pt-IrO2 electrodes

    Directory of Open Access Journals (Sweden)

    Konan Honoré Kondro

    2008-04-01

    Full Text Available Different IrO2 electrodes in which the molar percentage of platinum (Pt varies from 0 %mol Pt to 100 %mol Pt were prepared on titanium (Ti substrate by thermal decomposition techniques. The electrodes were characterized physically (SEM, XPS and electrochemically and then applied to methanol oxidation. The SEM micrographs indicated that the electrodes present different morphologies depending on the amount of platinum in the deposit and the cracks observed on the 0 %mol Pt electrode diminish in size tending to a compact and rough surface for 70 %mol Pt electrode. XPS results indicate good quality of the coating layer deposited on the titanium substrate. The voltammetric investigations in the supporting electrolyte indicate that the electrodes with low amount of platinum (less than 10 %mol Pt behave as pure IrO2. But in the case of electrodes containing more than 40 %mol Pt, the voltammograms are like that of platinum. Electrocatalytic activity towards methanol oxidation was observed with the electrodes containing high amount of platinum. Its oxidation begins at a potential of about 210 mV lower on such electrodes than the pure platinum electrode (100 %mol Pt. But for electrode containing low quantity of Pt, the surface of the coating is essentially composed of IrO2 and methanol oxidation occurs in the domain of water decomposition solely. The increase of the electrocatalytic behaviour of the electrodes containing high amount of Pt towards methanol oxidation is due to the bifunctional behaviour of the electrodes.

  5. Alkaloids extract of Retama monosperma (L.) Boiss. seeds used as novel eco-friendly inhibitor for carbon steel corrosion in 1 M HCl solution: Electrochemical and surface studies

    Energy Technology Data Exchange (ETDEWEB)

    El Hamdani, Naoual; Fdil, Rabiaa [Laboratoire de Chimie Bioorganique, Faculté des Sciences, Université Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco); Tourabi, Mustapha [Laboratoire de Catalyse et de Corrosion des Matériaux (LCCM), Faculté des Sciences, Université Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco); Jama, Charafeddine [UMET-PSI, CNRS UMR 8207, ENSCL, Université Lille 1, CS 90108, F-59652 Villeneuve d’Ascq Cedex (France); Bentiss, Fouad, E-mail: fbentiss@enscl.fr [Laboratoire de Catalyse et de Corrosion des Matériaux (LCCM), Faculté des Sciences, Université Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco); UMET-PSI, CNRS UMR 8207, ENSCL, Université Lille 1, CS 90108, F-59652 Villeneuve d’Ascq Cedex (France)

    2015-12-01

    Graphical abstract: - Highlights: • AERS is good eco-friendly corrosion inhibitor for carbon steel in 1 M HCl. • AERS acts as mixed-type inhibitor in 1 M HCl medium. • AERS adsorption is well described by Langmuir isotherm. • Surface analyses were used to explain the AERS mechanism of carbon steel corrosion inhibition. - Abstract: Current research efforts now focus on the development of non-toxic, inexpensive and environmentally friendly corrosion inhibitors as alternatives to different organic and non-organic compounds. In this field, alkaloids extract of Retama monosperma (L.) Boiss. seeds (AERS) was tested for the first time as corrosion inhibitor for carbon steel in 1 M HCl medium using electrochemical and surface characterization techniques. The obtained results showed that this plant extract's acts as an efficient corrosion inhibitor for carbon steel in 1 M HCl and an inhibition efficiency of 94.4% was reached with 400 mg/L of AERS at 30 °C. Ac impedance experimental data revealed a frequency distribution of the capacitance, simulated as constant phase element. Impedance results demonstrated that the addition of the AERS in the corrosive solution decreases the charge capacitance and simultaneously increases the function of the charge/discharge of the interface, facilitating the formation of an adsorbed layer over the steel surface. Polarization curves indicated that AERS is a mixed inhibitor. Adsorption of such alkaloid extract on the steel surface obeyed to the Langmuir adsorption isotherm. X-ray photoelectron spectroscopy (XPS) showed that the inhibition of steel corrosion in normal hydrochloric solution by AERS is mainly controlled by a physisorption process and the inhibitive layer is composed of an iron oxide/hydroxide mixture where AERS molecules are incorporated.

  6. The effect of boron implantation on the corrosion behaviour, microhardness and contact resistance of copper and silver surfaces

    International Nuclear Information System (INIS)

    Henriksen, O.; Johnson, E.; Johansen, A.; Sarholt-Kristensen, L.

    1986-01-01

    In order to investigate the influence of boron implantation on the corrosion resistance of electrical contacts, a number of pure copper, pure silver and copper edge connector samples have been implanted with boron (40 keV) to fluences of 5.10 20 m -2 and 2.10 21 m -2 . Atmospheric corrosion tests of the implanted species were conducted using the following exposures: H 2 S (12.5 ppm, 4 days), SO 2 (25 ppm, 21 days), saltfog (5% NaCl, 1 day), moist air (93% RH, 56 days), and hot/dry air (70 C, 56 days). The boron implantations lead to a significant reduction in the sulphidation rate of copper and silver. The corrosive film formed during exposure in H 2 S and SO 2 atmospheres is confined to pitted regions on the implanted areas, while a thick and relatively uniform film formation is observed on the unimplanted samples. The corrosion resistance of copper and silver in saltfog atmosphere is somewhat improved by boron implantation, whilst the results from exposures to moist air or hot/dry air are inconclusive. The improved corrosion behaviour is accompanied by an increase in the contact resistance and in the microhardness of the implanted samples. (orig.)

  7. Effect of laser-arc hybrid welding on fracture and corrosion behaviour of AA6061-T6 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Daquan, E-mail: zhdq@sh163.net [Department of Environmental Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Jin Xin; Gao Lixin [Department of Environmental Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Joo, Hyung Goun [Stress Analysis and Failure Design Laboratory, School of Mechanical Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Lee, Kang Yong, E-mail: KYL2813@yonsei.ac.kr [Stress Analysis and Failure Design Laboratory, School of Mechanical Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2011-03-15

    Research highlights: {yields} A dendritic cellular structure was formed in the weld fusion zone (WFZ) and caused alloying element segregation. {yields} The precipitation of intermetallic phases and the formation of galvanic corrosion couplings contribute to the improving pitting susceptibility in the WFZ. {yields} The intergranular corrosion nucleates on pit walls and spreads from them. - Abstract: The welding condition of the hybrid laser-gas metal arc (GMA) welding for AA6061-T6 alloy was optimized by tensile test. Formability performance was checked by the bend test. Fractographic analysis indicates a large number of fine ductile type voids in the fracture surface. The microstructure measurements exhibit a dendritic cellular structure in the weld fusion zone (WFZ) and a partially melted zone adjacent to the fusion boundaries. The corrosion behaviour of the weldment and the base alloy were investigated by weight-loss test in nitric acid solution. The WFZ suffers more severe pitting than the rest regions in the weldment. It shows that corrosion cracking is owing to the precipitation of intermetallic phases and the formation of galvanic corrosion couplings in the weldment of AA6061-T6 alloy.

  8. Surface characterisation and electrochemical behaviour of porous titanium dioxide coated 316L stainless steel for orthopaedic applications

    International Nuclear Information System (INIS)

    Nagarajan, S.; Rajendran, N.

    2009-01-01

    Porous titanium dioxide was coated on surgical grade 316L stainless steel (SS) and its role on the corrosion protection and enhanced biocompatibility of the materials was studied. X-ray diffraction analysis (XRD), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) were carried out to characterise the surface morphology and also to understand the structure of the as synthesised coating on the substrates. The corrosion behaviour of titanium dioxide coated samples in simulated body fluid was evaluated using polarisation and impedance spectroscopy studies. The results reveal that the titanium dioxide coated 316L SS exhibit a higher corrosion resistance than the uncoated 316L SS. The titanium dioxide coated surface is porous, uniform and also it acts as a barrier layer to metallic substrate and the porous titanium dioxide coating induces the formation of hydroxyapatite layer on the metal surface.

  9. The use of electrochemical measurement techniques towards quality control and optimisation of corrosion properties of thermal spray coatings

    NARCIS (Netherlands)

    Vreijling, M.P.W.; Hofman, R.; Westing, E.P.M. van; Ferrari, G.M.; Wit, J.H.W. de

    1998-01-01

    Metal spray coatings are ever more recognised as a possible superior means of corrosion protection in many environments. Extended service life combined with little or no maintenance provides interesting opportunities for both environmentalists and corrosion engineers. Although many successful

  10. Corrosion behaviour of steel during accelerated carbonation of solutions which simulate the pore concrete solution

    Directory of Open Access Journals (Sweden)

    Alonso, C.

    1987-06-01

    Full Text Available In spite of the numerous studies carried out on carbonation of the concrete, very few data have been published on the mechanism of steel depassivation and the corrosion rates involved in this type of phenomenon. Also some uncertainties remain as to the chemical composition of the pore solution of a carbonated concrete. Random behaviours related with the changes in the corrosion rate of steel during accelerated carbonation of cement mortars have suggested the need to study the process in a more simple medium which allows the isolation of the different parameters. Thus, saturated Ca(0H2 -base solutions with different additions of KOH and NaOH have been used to simulate the real pore concrete solution. In the present work, simultaneous changes in the pH value, corrosion potential and corrosion rate (measured by means of the determination of the Polarization Resistance of steel roads have been monitored during accelerated carbonation produced by a constant flux through the solution of CO2 gas and/or air.

    A pesar de los numerosos estudios realizados en torno a la carbonatación del hormigón, son muy pocos los datos publicados acerca del mecanismo de despasivación del acero y las velocidades de corrosión implicadas en el proceso de corrosión por carbonatación. Por otra parte, aún no se conoce la composición de la fase acuosa de un hormigón carbonatado. Cierta erraticidad en los cambios registrados en la velocidad de corrosión del acero durante la carbonatación acelerada de morteros de cemento, puso de manifiesto la necesidad del estudio del proceso en un sistema simplificado que permitiera considerar aisladamente cada uno de los distintos parámetros. A este fin se utilizaron como disoluciones de simulación de la fase acuosa intersticial del hormigón, disoluciones saturadas de Ca(0H2 con distintas adiciones de NaOH o KOH. En el presente trabajo, se han registrado simultáneamente los cambios en

  11. The effect of mucin, fibrinogen and IgG on the corrosion behaviour of Ni-Ti alloy and stainless steel.

    Science.gov (United States)

    Chao, Zhang; Yaomu, Xiao; Chufeng, Liu; Conghua, Liu

    2017-06-01

    In this study, Ni-Ti alloy and stainless steal were exposed to artificial saliva containing fibrinogen, IgG or mucin, and the resultant corrosion behavior was studied. The purpose was to determine the mechanisms by which different types of protein contribute to corrosion. The effect of different proteins on the electrochemical resistance of Ni-Ti and SS was tested by potentiodynamic polarization, and the repair capacity of passivation film was tested by cyclic polarization measurements. The dissolved corrosion products were determined by ICP-OES, and the surface was analyzed by SEM and AFM. The results showed fibrinogen, IgG or mucin could have different influences on the susceptibility to corrosion of the same alloy. Adding protein lead to the decrease of corrosion resistance of SS, whereas protein could slow down the corrosion process of Ni-Ti. For Ni-Ti, adding mucin could enhance the corrosion stability and repair capacity of passivation film. The susceptibility to pitting corrosion of Ni-Ti and stainless steal in fibrinogen AS is not as high as mucin and IgG AS. There are different patterns of deposition formation on the metal surface by different types of protein, which is associated with their effects on the corrosion process of the alloys.

  12. Electrochemical noise measurements of steel corrosion in the molten NaCl-K2SO4 system

    DEFF Research Database (Denmark)

    Cappeln, Frederik Vilhelm; Bjerrum, Niels; Petrushina, Irina

    2005-01-01

    -called active corrosion (i.e., the corrosion proceeds with no passivation due to the influence of chlorine), characterized by the formation of volatile metal chlorides as a primary corrosion product. It was found possible to obtain an empirical separation of general and intergranular corrosion using kurtosis (a...... on this basis. Approximate values of polarization resistances of AISI347 and 15Mo3 steels were determined to be 250 and 100 Omega cm(2), respectively....

  13. Results from a Novel Method for Corrosion Studies of Electroplated Lithium Metal Based on Measurements with an Impedance Scanning Electrochemical Quartz Crystal Microbalance

    Directory of Open Access Journals (Sweden)

    Martin Winter

    2013-07-01

    Full Text Available A new approach to study the chemical stability of electrodeposited lithium on a copper metal substrate via measurements with a fast impedance scanning electrochemical quartz crystal microbalance is presented. The corrosion of electrochemically deposited lithium was compared in two different electrolytes, based on lithium difluoro(oxalato borate (LiDFOB and lithium hexafluorophosphate, both salts being dissolved in solvent blends of ethylene carbonate and diethyl carbonate. For a better understanding of the corrosion mechanisms, scanning electron microscopy images of electrodeposited lithium were also consulted. The results of the EQCM experiments were supported by AC impedance measurements and clearly showed two different corrosion mechanisms caused by the different salts and the formed SEIs. The observed mass decrease of the quartz sensor of the LiDFOB-based electrolyte is not smooth, but rather composed of a series of abrupt mass fluctuations in contrast to that of the lithium hexafluorophosphate-based electrolyte. After each slow decrease of mass a rather fast increase of mass is observed several times. The slow mass decrease can be attributed to a consolidation process of the SEI or to the partial dissolution of the SEI leaving finally lithium metal unprotected so that a fast film formation sets in entailing the observed fast mass increases.

  14. Corrosion behaviour of container materials for geological disposal of high-level waste

    International Nuclear Information System (INIS)

    Haijtink, B.

    1986-01-01

    Within the framework of the Community R and D programme on management and storage of radioactive waste (shared cost action), a research activity is aiming at the assessment of the corrosion behaviour of potential container materials for the geological disposal of vitrified high-level waste. In a joint programme, three promising reference materials are being tested in environments representative of the three considered geological formations, clay, salt and granite. Samples of the three reference materials, Ti-0.2% Pd, Hastelloy C 4 and a low carbon steel were provided by the Commission to the participating laboratories respectively: Studiecentrum voor Kernenergie (SCK/CEN) at Mol (Belgium), Kernforschungszentrum (KfK) at Karlsruhe (Federal Republic of Germany), Commissariat a l'Energie Atomique (CEA) at Fontenay-aux-Roses (France), the Atomic Energy Research Establishment (AERE) at Harwell (United Kingdom) and the Centre National de la Recherche Scientifique (CNRS) at Vitry (France). In this report, the results obtained during the year 1984 are described

  15. Effect of Metakaolin and Slag blended Cement on Corrosion Behaviour of Concrete

    Science.gov (United States)

    Borade, Anita N.; Kondraivendhan, B.

    2017-06-01

    The present paper is aimed to investigate the influence of Metakaolin (MK) and Portland slag Cement (PSC) on corrosion behaviour of concrete. For this purpose, Ordinary Portland Cement (OPC) was replaced by 15% MK by weight and readymade available PSC were used. The standard concrete specimens were prepared for both compressive strength and half- cell potential measurement. For the aforesaid experiments, the specimens were cast with varying water to binder ratios (w/b) such as 0.45, 0.5 and 0.55 and exposed to 0%, 3%, 5% and 7.5% of sodium chloride (NaCl) solution. The specimens were tested at wide range of curing ages namely 7, 28, 56, 90 and 180 days. The effects of MK, w/b ratio, age, and NaCl exposure upon concrete were demonstrated in this investigation along with the comparison of results of both MK and PSC concrete were done. It was also observed that concrete with MK shows improved performance as compared to concrete with PSC.

  16. Electrochemical behaviour of Cu (II)/Cu (I) redox couple in 1-hexyl-3 ...

    Indian Academy of Sciences (India)

    methylimidazolium chloride (C6mimCl) ionic liquid was studied using glassy carbon electrode at 375 K by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy. In this electrochemical study, we have made an attempt ...

  17. On the properties of two binary NiTi shape memory alloys. Effects of surface finish on the corrosion behaviour and in vitro biocompatibility.

    Science.gov (United States)

    Es-Souni, Mohammed; Es-Souni, Martha; Fischer-Brandies, Helge

    2002-07-01

    The present paper compares the transformation behaviour and mechanical properties of two orthodontic wires of close chemical compositions. The effects of surface topography and surface finish residues on the potentiodynamic corrosion behaviour and biocompatibility are also reported. The cytotoxicity tests were performed on both alloys in fibroblast cell cultures from human gingiva using the MTT test. It is shown that the surface finish and the amounts of surface finish residues affect dramatically the corrosion resistance. Bad surface finish results in lower corrosion resistance. The in vitro biocompatibility, though not affected to the extent of corrosion resistance, is also reduced as the surface roughness and the amounts of residues increase. This is thought to be due to surface effects on corrosion and metallic ions release.

  18. Electrochemical profiling of multi-clad aluminium sheets used in automotive heat exchangers

    DEFF Research Database (Denmark)

    Bordo, Kirill; Gudla, Visweswara Chakravarthy; Peguet, Lionel

    2018-01-01

    A combination of glow discharge optical emission spectroscopy sputtering and local electrochemical measurements was used to determine electrochemical changes upon brazing in a multi-layered Aluminium sheet (AA4343/AA3xxx/AA4343) with an additional low-Cu (AA3xxx) interlayer. Ecorr values from pot...... of conventional sheet, whereas presence of interlayer reduced outward diffusion of Cu and hence improved corrosion protection....... potentiodynamic polarization, galvanic corrosion behaviour by ZRA, microstructure and composition by SEM and TEM were investigated and compared to those obtained for sheet without the interlayer. Inward diffusion of Si from clad, and outward diffusion of Cu from core are found to degrade the corrosion properties...

  19. Influence of the surface finishing on the corrosion behaviour of AISI 316L stainless steel

    Czech Academy of Sciences Publication Activity Database

    Dundeková, S.; Zatkalíková, V.; Fintová, Stanislava; Hadzima, B.; Škorík, Viktor

    2015-01-01

    Roč. 22, č. 1 (2015), s. 48-53 ISSN 1335-0803 R&D Projects: GA MŠk(CZ) EE2.3.30.0063 Institutional support: RVO:68081723 Keywords : AISI 316L stainless steel * Corrosion * Immersion test * Corrosion rate Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://ojs.mateng.sk/index.php/Mateng/article/view/166/251

  20. Effect of Exchanging Advancing and Retreating Side Materials on Mechanical Properties and Electrochemical Corrosion Resistance of Dissimilar 6013-T4 and 7003 Aluminum Alloys FSW Joints

    Science.gov (United States)

    Zhao, Zhixia; Liang, Haimei; Zhao, Yong; Yan, Keng

    2018-03-01

    Friction stir welding (FSW) was used to weld dissimilar joints between Al 6013-T4 and Al7003 alloys in this work. The effect of exchanging advancing (AS) and retreating (RS) side material on microstructure, mechanical behaviors and electrochemical corrosion resistance was discussed. Results showed that different joint cross sections were obtained when exchanging AS and RS materials. The material on the AS would be more deformed during the welding process. When the Al6013 placed on the AS, the plastic flow of weld is more sufficient. Whether on the AS or RS, the Al6013-T4 side is the weak region for both tensile specimens and hardness samples. The fracture position corresponds to the minimum hardness position. Also, more strengthening phase can be retained in the joint, and the joint of A6R7 has better corrosion resistance.