Study on corrosion of carbon steel in DEA aqueous solutions

Science.gov (United States)

Yang, Jun Han; Xie, Jia Lin; Zhang, Li

2018-02-01

Corrosion of carbon steel in the CO2 capture process using diethanolamine (DEA) aqueous solutions was investigated. The effects of the mass concentrations of DEA, solution temperature and CO2 loading on the corrosion rate of carbon steel were demonstrated. The experimental results provided comprehensive information on the appropriate concentration range of DEA aqueous solutions under which low corrosion of carbon steel can be achieved.

Effects of surface condition on aqueous corrosion and environmental embrittlement of iron aluminides

Energy Technology Data Exchange (ETDEWEB)

Perrin, R.L.; Buchanan, R.A. [Univ. of Tennessee, Knoxville, TN (United States)

1996-08-01

Effects of retained high-temperature surface oxides, produced during thermomechanical processing and/or heat treatment, on the aqueous-corrosion and environmental-embrittlement characteristics of Fe{sub 3}Al-based iron aluminides (FA-84, FA-129 and FAL-Mo), a FeAl-based iron aluminide (FA-385), and a disordered low-aluminum Fe-Al alloy (FAPY) were evaluated. All tests were conducted at room temperature in a mild acid-chloride solution. In cyclic-anodic-polarization testing for aqueous-corrosion behavior, the surface conditions examined were: as-received (i.e., with the retained high-temperature oxides), mechanically cleaned and chemically cleaned. For all materials, the polarization tests showed the critical pitting potentials to be significantly lower in the as-received condition than in the mechanically-cleaned and chemically-cleaned conditions. These results indicate detrimental effects of the retained high-temperature oxides in terms of increased susceptibilities to localized corrosion. In 200-hour U-bend stress-corrosion-cracking tests for environmental-embrittlement behavior, conducted at open-circuit corrosion potentials and at a hydrogen-charging potential of {minus}1500 mV (SHE), the above materials (except FA-385) were examined with retained oxides and with mechanically cleaned surfaces. At the open-circuit corrosion potentials, none of the materials in either surface condition underwent cracking. At the hydrogen-charging potential, none of the materials with retained oxides underwent cracking, but FA-84, FA-129 and FAL-Mo in the mechanically cleaned condition did undergo cracking. These results suggest beneficial effects of the retained high-temperature oxides in terms of increased resistance to environmental hydrogen embrittlement.

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.

Corrosion characteristics of an aqueous self-cooled fusion blanket

International Nuclear Information System (INIS)

Bogaerts, W.F.; Embrechts, M.J.; Steiner, D.; Deutsch, L.; Jackson, D.

1986-01-01

A novel aqueous self-cooled blanket concept (ASCB) has recently been proposed. This blanket concept, as applied to a MARS-like tandem mirror reactor, consists of disks of spiraling tubes of Zircaloy-4 housed in a structural container of vanadium alloy (V-15 Ti-5 Cr). The Zircaloy tubes are cooled by a mixture of light and heavy water with 9 g of LiOH per 100 cm 3 of water dissolved in the coolant. A major issue for the feasibility of the integrated blanket coil concept is the chemical compatibility of the coolant and Zircaloy. Initial corrosion tests have been undertaken in order to resolve this question. Results clearly show that successful alloy heats can be prepared, for which corrosion problems will probably not be the limiting factor of the ASCB design concept. As is quite well known from fission engineering studies, small variations in the alloy compositions or in the metallurgical structure may, however, be able to cause significant alterations in the oxidation or corrosion rates. Further tests will be necessary to resolve the remaining uncertainties and to determine the behavior of successful alloy heats in the presence of trace impurities in order to address the sensitivity to localized corrosion phenomena such as pitting, stress corrosion cracking, and intergranular attack

Corrosion resistance of amorphous and crystalline Pd40Ni40P20 alloys in aqueous solutions

DEFF Research Database (Denmark)

Wu, Y.F.; Chiang, Wen-Chi; Chu, J.

2006-01-01

The corrosion behaviors of amorphous and crystalline Pd40Ni40P20 alloys in various aqueous solutions are reported in this paper. The corrosion resistance of crystalline (annealed) Pd40Ni40P20 is better than that of amorphous Pd40Ni40P20 in various corrosive solutions, due to crystalline Pd40Ni40P20...... and mainly consists of inert Pd5P2, NI3P, Ni2Pd2P and noble Pd phases. These inert and noble properties result in a higher corrosion resistance in crystalline Pd40Ni40P20....

Radiolysis and corrosion aspects of the aqueous self-cooled blanket concept

International Nuclear Information System (INIS)

Bruggeman, A.; Snykers, M.; Bogaerts, W.F.; Waeben, R.; Embrechts, M.J.; Steiner, D.

1989-01-01

Corrosion and radiolysis aspects of the Aqueous Self-Cooled Blanket concept, proposed as a potential shielding breeding blanket for near term fusion devices and fusion reactors, have been investigated. On the basis of preliminary results for selected aqueous solutions of lithium compounds, no particular corrosion problems have been revealed for the low-temperature concept envisaged for NET and radiolysis effects might be controlled by appropriate countermeasures. For the reactor-relevant high-temperature concept particular attention has to be paid to intergranular stress-corrosion and to the synergistic radiolysis-corrosion effects. Further information is needed from tests performed in relevant operational conditions. (orig.)

Correlation between the oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys

Science.gov (United States)

Park, Sang-Yoon; Lee, Myung-Ho; Jeong, Yong-Hwan; Jung, Youn-Ho

2004-12-01

The correlation between the oxide impedance and corrosion behavior of two series of Zr-Nb-Sn-Fe-Cu alloys was evaluated. Corrosion tests were performed in a 70 ppm LiOH aqueous solution at 360°C for 300 days. The results of the corrosion tests revealed that the corrosion behavior of the alloys depended on the Nb and Sn content. The impedance characteristics for the pre- and post-transition oxide layers formed on the surface of the alloys were investigated in sulfuric acid at room temperature. From the results, a pertinent equivalent circuit model was preferably established, explaining the properties of double oxide layers. The impedance of the oxide layers correlated with the corrosion behavior; better corrosion resistance always showed higher electric resistance for the inner layers. It is thus concluded that a pertinent equivalent circuit model would be useful for evaluating the long-term corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys.

Modelling aqueous corrosion of nuclear waste phosphate glass

Energy Technology Data Exchange (ETDEWEB)

Poluektov, Pavel P.; Schmidt, Olga V.; Kascheev, Vladimir A. [Bochvar All-Russian Scientific Research Institute for Inorganic Materials (VNIINM), Moscow (Russian Federation); Ojovan, Michael I., E-mail: m.ojovan@sheffield.ac.uk [Immobilisation Science Laboratory, Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom)

2017-02-15

A model is presented on nuclear sodium alumina phosphate (NAP) glass aqueous corrosion accounting for dissolution of radioactive glass and formation of corrosion products surface layer on the glass contacting ground water of a disposal environment. Modelling is used to process available experimental data demonstrating the generic inhibiting role of corrosion products on the NAP glass surface. - Highlights: • The radionuclides yield is determined by the transport from the glass through the surface corrosion layer. • Formation of the surface layer is due to the dissolution of the glass network and the formation of insoluble compounds. • The model proposed accounts for glass dissolution, formation of corrosion layer, specie diffusion and chemical reactions. • Analytical solutions are found for corrosion layer growth rate and glass components component leaching rates.

Corrosion Behavior and Oxide Film Formation of T91 Steel under Different Water Chemistry Operation Conditions

Energy Technology Data Exchange (ETDEWEB)

Zhang, D. Q.; Shi, C.; Li, J.; Gao, L. X. [Shanghai University of Electric Power, Shanghai (China); Lee, K. Y. [Dalian University of Technology, Dalian (China)

2017-02-15

The corrosion behavior of a ferritic/martensitic steel T91 exposed to an aqueous solution containing chloride and sulfate ions is investigated depending on the stimulated all-volatile treatment (AVT) and under oxygenated treatment (OT) conditions. The corrosion of T91 steel under OT condition is severe, while the corrosion under AVT condition is not. The co-existence of chloride and sulfate ions has antagonistic effect on the corrosion of T91 steel in both AVT and OT conditions. Unlike to corrosion resistance in the aqueous solution, OT pretreatment provides T91 steel lower oxidation-resistance than VAT pretreatment. From scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis, the lower corrosion resistance in the aqueous solution by VAT conditions possibly is due to the formation of pits. In addition, the lower oxidation resistance of T91 steel pretreated by OT conditions is explained as follows: the cracks formed during the immersion under OT conditions accelerated peeling-off rate of the oxide film.

Pitting corrosion of zirconium in aqueous solution

International Nuclear Information System (INIS)

El Shayeb, H.A.; Abd El Wahab, F.M.; Abd Elk Meguid, E.A.

1994-01-01

The open circuit potentials of the Zr electrode are followed as a function of time in various aqueous solutions till attainment of steady state values.The results are discussed on the basis of oxide film thickening and repair. Pitting corrosion of Zr was examined in chloride solutions using the potentiodynamic technique. The effect of some inorganic and organic additives was also investigated for inhibiting the pitting corrosion of Zr and the relative performance is presented and discussed. (author). 21 refs., 6 figs., 1 tab

Study of the corrosion behavior of magnesium alloy weddings in NaCl solutions by gravimetric tests

Energy Technology Data Exchange (ETDEWEB)

Segarra, J. A.; Calderon, B.; Portoles, A.

2015-07-01

In this article, the corrosion behavior of commercial AZ31 welded plates in aqueous chloride media was investigated by means of gravimetric techniques and Neutral Salt Spray tests (NSS). The AZ31 samples tested were welded using Gas Tugsten Arc Welding (GTAW) and different filler materials. Material microstructures were investigated by optical microscopy to stablish the influence of those microstructures in the corrosion behavior. Gravimetric and NSS tests indicate that the use of more noble filler alloys for the sample welding, preventing the reduction of aluminum content in weld beads, does not imply a better corrosion behavior. (Author)

Effect of Ti3+ ion on the Corrosion Behavior of Alloy 600

International Nuclear Information System (INIS)

Lee, Chang Bong; Lim, Han Gwi; Kim, Bok Hee; Kim, Ki Ju

1999-01-01

Alloy 600 has been widely used as a steam generator tubing material in pressurized water reactors(PWRs) nuclear power plants. Corrosion of steam generator tubing mainly occurs on the secondary water side. The purpose of this work is primarily concerned with examining the effect of Ti 3+ ion concentrations on the corrosion behavior of the Alloy 600 steam generator tubing material. Corrosion behavior of the Alloy 600 steam generator tubing material was studied in aqueous solutions with varying Ti 3+ ion concentration at room temperature. Potentiodynamic and potentiostatic polarization techniques were used to determine the corrosion and pitting potentials for the Alloy 600 test material. The addition of Ti 3+ ion to 1000ppm, showed inhibition effect on the corrosion of Alloy 600. But the corrosion of Alloy 600 was accelerated when the concentration of Ti 3+ ion exceeded 1000ppm, it is assumed that the effect of general corrosion of Alloy 600 is more sensitive than pitting corrosion. It is considered that the passive film which was formed on the Alloy 600 surface in the 100ppm Ti 3+ ion containing solution is mainly consisted of TiO 2

The Hydrogen Pickup Behavior for Zirconium-based Alloys in Various Out-of-pile Corrosion Test Conditions

Energy Technology Data Exchange (ETDEWEB)

Aomi, M.; Etoh, Y.; Ishimoto, S.; Une, K. [Nippon Nuclear Fuel Development, Co., Ltd., 2163 Narita-cho, Oarai-machi, Ibaraki-ken, 311-1313 (Japan); Ito, K. [Global Nuclear Fuel Japan Co., Ltd., 3-1 Uchikawa 2-chome, Yokosuka-shi, Kanagawa-ken, 239-0836 (Japan)

2009-06-15

An acceleration of hydrogen absorption in zirconium alloy claddings at high burnups is one of the most important issues limiting the fuel performance from the viewpoint of cladding integrity. In this context, advanced cladding materials with higher corrosion resistant and lower hydrogen absorption properties have been widely searched in various organizations. In this study, four kinds of zirconium-based alloys, whose in-pile data had been acquired [1,2] were subjected to comprehensive out-of-pile corrosion tests with various temperature and atmosphere conditions in order to investigate the correlation between in-pile and out-of-pile corrosion and hydrogen pick-up behavior, i.e. Zry-2, GNF-Ziron (Zry-2-based alloy with {approx}0.25 wt % of Fe), Hi-FeNi Zircaloy (Zry-2-based alloy with {approx}0.25 wt % of Fe and {approx}0.1 wt% Ni), and VB (Zr-based alloy containing Sn, Cr, and {approx}0.5 wt % of Fe). All the alloys were annealed in RXA condition. The out-of-pile corrosion tests were carried out in three different conditions of 400 deg. C steam, 475 deg. C supercritical water, and 290 deg. C LiOH aqueous solution. In addition to these alloys, several Zry-2-based alloys with various iron contents were tested in 290 deg. C LiOH aqueous solution. Among the four corrosion conditions, the 290 deg. C LiOH aqueous solution test well screened the hydrogen pick-up behavior of the alloys. The hydrogen absorption decreased with higher iron contents in the alloys in both the out-of-pile and in-pile conditions. Especially, the distinct suppression of hydrogen absorption was observed for VB with the highest iron content. The similar dependence of iron content on the hydrogen pick-up fraction was also obtained for the Zry-2-based alloys with different iron contents, which were corroded in the 290 deg. C LiOH aqueous solution condition. As for the corrosion behavior in the 290 deg. C LiOH aqueous solution condition, the weight gains of Zry-2, GNF-Ziron and VB followed the 1

Corrosion of beryllium

International Nuclear Information System (INIS)

Mueller, J.J.; Adolphson, D.R.

1987-01-01

The corrosion behavior of beryllium in aqueous and elevated-temperature oxidizing environments has been extensively studied for early-intended use of beryllium in nuclear reactors and in jet and rocket propulsion systems. Since that time, beryllium has been used as a structural material in les corrosive environments. Its primary applications include gyro systems, mirror and reentry vehicle structures, and aircraft brakes. Only a small amount of information has been published that is directly related to the evaluation of beryllium for service in the less severe or normal atmospheric environments associated with these applications. Despite the lack of published data on the corrosion of beryllium in atmospheric environments, much can be deduced about its corrosion behavior from studies of aqueous corrosion and the experiences of fabricators and users in applying, handling, processing, storing, and shipping beryllium components. The methods of corrosion protection implemented to resist water and high-temperature gaseous environments provide useful information on methods that can be applied to protect beryllium for service in future long-term structural applications

Effects of Friction Stir Welding on Corrosion Behaviors of AA2024-T4 Aluminum Alloy

Directory of Open Access Journals (Sweden)

Ales Steve Korakan

2017-01-01

Full Text Available In this work, the corrosion behavior of welded joints of AA2024-T4 Al alloy produced by friction stir welding process has been investigated. Tests were performed in an aerated 3.5% NaCl aqueous solution with pH = 7 at 20±2°C. Corrosion rate and corrosion morphology of weld regions were evaluated and compared to those of the parent metal. The microstructure of weld nugget, thermomechanical affected zone, heated affected zone, and parent metal were analyzed using scanning electron microscopy and energy dispersive spectroscopy. It was observed that corrosion initiated at FSW related spots and the sizes of local corrosion increased with time.

Potassium sorbate-A new aqueous copper corrosion inhibitor

International Nuclear Information System (INIS)

Abelev, Esta; Starosvetsky, David; Ein-Eli, Yair

2007-01-01

This work presents the novel nature of 2,4-hexadienoic acid potassium salt (potassium sorbate (KCH 3 CH=CHCH=CHCO 2 )) as an effective copper aqueous corrosion inhibitor. The influence of pH and potassium sorbate concentration on copper corrosion in aerated sulfate and chloride solutions is reported. Degree of copper protection was found to increase with an increase in potassium sorbate concentration; an optimum concentration of this inhibitor in sulfate solutions was found to be 10 g/L. Copper is highly resistant to corrosion attacks by chloride ions in the presence of potassium sorbate. X-ray photoelectron spectroscopy (XPS) studies suggest that copper protection is achieved via the formation of a mixed layer of cuprous oxide, cupric hydroxide and copper(II)-sorbate at the metal surface

The corrosion behavior of the T1 (Al2CuLi) intermetallic compound in aqueous environments

Science.gov (United States)

Buchheit, R. G.; Stoner, G. E.

1989-01-01

The intermetallic compound T1 (Al2CuLi) is suspected to play an important role in the localized corrosion at subgrain boundaries in Al-Li-Cu alloys. The intermetallic was synthesized for characterization of its corrosion behavior. Experiments performed included open circuit potential measurements, potentiodynamic polarization, and corrosion rate vs. pH in solutions whose pH was varied over the range of 3 to 11. Subgrain boundary pitting and continuous subgrain boundary corrosion are discussed in terms of the data obtained. Evidence suggesting the dealloying of copper from this compound is also presented.

Corrosion behavior of aluminum doped diamond-like carbon thin films in NaCl aqueous solution.

Science.gov (United States)

Khun, N W; Liu, E

2010-07-01

Aluminum doped diamond-like carbon (DLC:Al) thin films were deposited on n-Si(100) substrates by co-sputtering a graphite target under a fixed DC power (650 W) and an aluminum target under varying DC power (10-90 W) at room temperature. The structure, adhesion strength and surface morphology of the DLC:Al films were characterized by X-ray photoelectron spectroscopy (XPS), micro-scratch testing and atomic force microscopy (AFM), respectively. The corrosion performance of the DLC:Al films was investigated by means of potentiodynamic polarization testing in a 0.6 M NaCl aqueous solution. The results showed that the polarization resistance of the DLC:Al films increased from about 18 to 30.7 k(omega) though the corrosion potentials of the films shifted to more negative values with increased Al content in the films.

Aqueous corrosion of borosilicate glasses. Nature and properties of alteration layers

International Nuclear Information System (INIS)

Trotignon, Laurent

1990-01-01

This research thesis addresses physical and chemical processes which occur during aqueous corrosion of silicates, and the study of the properties of their interfaces with solutions, and thus issues related to the fate of high activity nuclear wastes which are embedded in a vitreous matrix as the potential release of radionuclides towards the environment then depends on the glass parcel behaviour submitted to chemical attacks which could alter it, notably by aqueous corrosion. The objective is then to model the dissolution of nuclear glass over long periods of time, and to predict the behaviour of radionuclides. The author compared the corrosion and alteration layers of gradually more complex borosilicate glasses, from a ternary sodium borosilicate glass to a simulated nuclear glass (the French reference glass R7T7). Complexity is increased by adding oxides. After some theoretical recalls on the structure and corrosion of borosilicate glasses, the author presents the studied materials, the corrosion experiments, and analytical techniques used to study alteration layers. The mechanism of formation of altered layers is studied based on corrosion experiments performed at 90 C on the whole set of glasses. Alteration layers formed on corroded glasses are studied and compared by using various techniques: electronic microscopy, high energy ion beams, spectroscopy, infrared, photo-electron spectroscopy. Implications for underground storage of nuclear glasses are discussed

Chemistry of the aqueous medium - Determining factor of corrosion in carbon steel components of secondary circuit

International Nuclear Information System (INIS)

Radulescu, M.; Pirvan, I.; Dinu, A.; Velciu, L.

2003-01-01

The interplay of chemistry of aqueous medium and corrosion processes followed by deposition and/or release of corrosion products determines both formation and growth of superficial films as well as the kinetics of ion release from materials into the aqueous medium. Material corrosion in the secondary circuit of a NPP can be minimized by choosing the materials of the components and by a rigorous inspection of the chemistry of aqueous agent. The chemical inspection helps in minimizing: - the corrosion of the components immersed in feedwater and vapor and of Steam Generator components; - 'dirtying' of the systems particularly of the surfaces implied in heat transfer; - the amount of insoluble chemical species resulting in corrosion process and carried along the circuit; - the corrosion of secondary circuit components during revisions or outages. An important role among the chemical parameters of the fluids circulated in NPP tubing appears to be the pH. In CANDU reactors it must be kept within the range of 8.7 to 9.4 by treating the medium with volatile amines (morpholine and cyclohexylamine). A plot is presented giving the corrosion rate of carbon steels as a function of the pH of the medium. Besides, the oxygen concentration dissolved in the aqueous medium must be maintained under 5 μg per water kg. Other factors determining the corrosion rates are also discussed. The paper gives the results of the experiments done with various materials, solutions and analysis methods

A review of the corrosion and pyrophoricity behavior of uranium and plutonium

International Nuclear Information System (INIS)

Totemeier, T.C.

1995-06-01

This report presents a review of the corrosion and pyrophoricity behavior of uranium and plutonium. For each element, the reactions with oxygen, water vapor, and aqueous solutions are described in terms of reaction rates, products, and mechanisms. Their pyrophoric tendencies in terms of measured ignition temperatures are discussed, and the effects of the important variables specific area, gas composition, and prior storage rare stated. The implications of the observed behavior for current storage issues are considered

Effect of pH on the corrosion behaviour of SUS321 in the ammonia aqueous solution

International Nuclear Information System (INIS)

Park, Sang Yoon; Jeong, Y. H.; Baek, J. H.; Choi, B. K.; Lee, M. H.; Choi, B. S.; Yoon, J. H.; Lee, D. J.

2003-02-01

The corrosion characteristics of SUS321 for pressure vessel of SMART in pure water, ammonia aqueous solutions of pH 8.5 ∼ 11.5 at 300 .deg. C were evaluated by using static autoclaves. SUS321 specimen in the high temperature ammonia aqueous solution has weight gain or loss by the 4 reactions. And it depends on the refreshing period of the aqueous solution. So additional experiments by recirculating loop system were required to evaluate the corrosion behaviour of SUS321 in the ammonia aqueous solution

Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content

Directory of Open Access Journals (Sweden)

Angeliki Lekatou

2016-02-01

Full Text Available Hypereutectic Al-Co alloys of various Co contents (7–20 weight % (wt.% Co were prepared by vacuum arc melting, aiming at investigating the influence of the cobalt content on the microstructure and corrosion behavior. Quite uniform and directional microstructures were attained. The obtained microstructures depended on the Co content, ranging from fully eutectic growth (7 wt.% and 10 wt.% Co to coarse primary Al9Co2 predominance (20 wt.% Co. Co dissolution in Al far exceeded the negligible equilibrium solubility of Co in Al; however, it was hardly uniform. By increasing the cobalt content, the fraction and coarseness of Al9Co2, the content of Co dissolved in the Al matrix, and the hardness and porosity of the alloy increased. All alloys exhibited similar corrosion behavior in 3.5 wt.% NaCl with high resistance to localized corrosion. Al-7 wt.% Co showed slightly superior corrosion resistance than the other compositions in terms of relatively low corrosion rate, relatively low passivation current density and scarcity of stress corrosion cracking indications. All Al-Co compositions demonstrated substantially higher resistance to localized corrosion than commercially pure Al produced by casting, cold rolling and arc melting. A corrosion mechanism was formulated. Surface films were identified.

Electrochemical corrosion behavior of carbon steel with bulk coating holidays

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

With epoxy coal tar as the coating material, the electrochemical corrosion behavior of Q235 with different kinds of bulk coating holidays has been investigated with EIS (Electrochemical Impedance Spectroscopy) in a 3.5vol% NaCl aqueous solution.The area ratio of bulk coating holiday to total coating area of steel is 4.91%. The experimental results showed that at free corrosionpotential, the corrosion of carbon steel with disbonded coating holiday is heavier than that with broken holiday and disbonded & broken holiday with time; Moreover, the effectiveness of Cathodic Protection (CP) of carbon steel with broken holiday is better than that with disbonded holiday and disbonded & broken holiday on CP potential -850 mV (vs CSE). Further analysis indicated that the two main reasons for corrosion are electrolyte solution slowly penetrating the coating, and crevice corrosion at steel/coating interface near holidays. The ratio of impedance amplitude (Z) of different frequency to minimum frequency is defined as K value. The change rate of K with frequency is related to the type of coating holiday.

Corrosion fatigue behavior of high strength brass in aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Hamada, A.S.; Kassem, M.A.; Ramadan, R.M.; El-Zeky, M.A. [Suez Canal Univ., Dept. of Metallurgy and Materials Engineering (Egypt)

2000-07-01

Corrosion fatigue behavior of British Standard high strength brass, CZ 127 has been studied in various environments, 3.5%NaC1 solution and 3.5%NaC1 containing 1000ppm ammonia by applying the reverse bending technique, strain-controlled cyclic, at 67 cycles/min. Characteristics of the produced alloy were studied using differential thermal analysis with applying its results in heat treating of the alloy; metallographic examinations; hardness measurements; X-ray; and electrochemical behavior of the unstressed alloy. CZ 127 was fatigued at three different conditions, solution treated, peak aged, and over aged at a fixed strain amplitude, 0.03 5. Solution treated alloy gave the best fatigue properties in all environments tested among the other materials. Results of the alloy studied were compared with that obtained of 70/30 {alpha}-brass. Fracture surface of the fatigued alloy was examined using optical microscope and scanning electron microscope equipped with EDX. (author)

Corrosion fatigue behavior of high strength brass in aqueous solutions

International Nuclear Information System (INIS)

Hamada, A.S.; Kassem, M.A.; Ramadan, R.M.; El-Zeky, M.A.

2000-01-01

Corrosion fatigue behavior of British Standard high strength brass, CZ 127 has been studied in various environments, 3.5%NaC1 solution and 3.5%NaC1 containing 1000ppm ammonia by applying the reverse bending technique, strain-controlled cyclic, at 67 cycles/min. Characteristics of the produced alloy were studied using differential thermal analysis with applying its results in heat treating of the alloy; metallographic examinations; hardness measurements; X-ray; and electrochemical behavior of the unstressed alloy. CZ 127 was fatigued at three different conditions, solution treated, peak aged, and over aged at a fixed strain amplitude, 0.03 5. Solution treated alloy gave the best fatigue properties in all environments tested among the other materials. Results of the alloy studied were compared with that obtained of 70/30 α-brass. Fracture surface of the fatigued alloy was examined using optical microscope and scanning electron microscope equipped with EDX. (author)

Corrosion penetration monitoring of advanced ceramics in hot aqueous fluids

Directory of Open Access Journals (Sweden)

Klaus G. Nickel

2004-03-01

Full Text Available Advanced ceramics are considered as components in energy related systems, because they are known to be strong, wear and corrosion resistant in many environments, even at temperatures well exceeding 1000 °C. However, the presence of additives or impurities in important ceramics, for example those based on Silicon Nitride (Si3N4 or Al2O3 makes them vulnerable to the corrosion by hot aqueous fluids. The temperatures in this type of corrosion range from several tens of centigrade to hydrothermal conditions above 100 °C. The corrosion processes in such media depend on both pH and temperature and include often partial leaching of the ceramics, which cannot be monitored easily by classical gravimetric or electrochemical methods. Successful corrosion penetration depth monitoring by polarized reflected light optical microscopy (color changes, Micro Raman Spectroscopy (luminescence changes and SEM (porosity changes will be outlined. The corrosion process and its kinetics are monitored best by microanalysis of cross sections, Raman spectroscopy and eluate chemistry changes in addition to mass changes. Direct cross-calibrations between corrosion penetration and mechanical strength is only possible for severe corrosion. The methods outlined should be applicable to any ceramics corrosion process with partial leaching by fluids, melts or slags.

Effects of annealing on tensile property and corrosion behavior of Ti-Al-Zr alloy

International Nuclear Information System (INIS)

Kim, Tae-Kyu; Choi, Byung-Seon; Jeong, Yong-Hwan; Lee, Doo-Jeong; Chang, Moon-Hee

2002-01-01

The effects of annealing on the tensile property and corrosion behavior of Ti-Al-Zr alloy were evaluated. The annealing in the temperature range from 500 to 800 deg. C for 1 h induced the growth of the grain and the precipitate sizes. The results of tensile tests at room temperature showed that the strengths and the ductility were almost independent of the annealing temperature. However, the results of corrosion test in an ammonia aqueous solution of pH 9.98 at 360 deg. C showed that the corrosion resistance depended on the annealing temperature, and the corrosion rate was accelerated with increasing annealing temperature. Hydrogen contents absorbed during the corrosion test of 220 days also increased with the annealing temperature. It could be attributed to the growth of Fe-rich precipitates by annealing. It is thus suggested that the lower annealing temperatures provide the better corrosion properties without degrading the tensile properties

Corrosion Behavior of Metal Active Gas Welded Joints of a High-Strength Steel for Automotive Application

Science.gov (United States)

Garcia, Mainã Portella; Mantovani, Gerson Luiz; Vasant Kumar, R.; Antunes, Renato Altobelli

2017-10-01

In this work, the corrosion behavior of metal active gas-welded joints of a high-strength steel with tensile yield strength of 900 MPa was investigated. The welded joints were obtained using two different heat inputs. The corrosion behavior has been studied in a 3.5 wt.% NaCl aqueous solution using electrochemical impedance spectroscopy and potentiodynamic polarization tests. Optical microscopy images, scanning electron microscopy and transmission electron microscopy with energy-dispersive x-ray revealed different microstructural features in the heat-affected zone (HAZ) and the weld metal (WM). Before and after the corrosion process, the sample was evaluated by confocal laser scanning microscopy to measure the depth difference between HAZ and WM. The results showed that the heat input did not play an important role on corrosion behavior of HSLA steel. The anodic and cathodic areas of the welded joints could be associated with depth differences. The HAZ was found to be the anodic area, while the WM was cathodic with respect to the HAZ. The corrosion behavior was related to the amount and orientation nature of carbides in the HAZ. The microstructure of the HAZ consisted of martensite and bainite, whereas acicular ferrite was observed in the weld metal.

Corrosion behavior of mild steel and SS 304L in presence of dissolved nickel under aerated and deaerated conditions

Directory of Open Access Journals (Sweden)

Mohd Mobin

2011-12-01

Full Text Available In dual purpose water/power co-generation plants, the presence of high concentration of Cu and Ni in the re-circulating brine/condensate as a result of condenser tubes corrosion has been attributed as one of the several causes of corrosion damage of flash chamber materials and water touched parts of the boilers. The present investigation deals with the effect of dissolved nickel in the concentration range of 10 ppb to 100 ppm on the corrosion behavior of mild steel and SS 304L in two aqueous medium namely, distilled water and artificial seawater. The effect of pH, dissolved oxygen and flow condition of aqueous medium on the corrosion behavior was also monitored. The experimental techniques include immersion test and electrochemical tests which include free corrosion potential measurements and potentiodynamic polarization measurements. The corrosion rate of mild steel and SS 304L under different experimental conditions was determined by weight loss method and spectrophotometric determination of iron ion entered into the test solution during the period of immersion. The pH of the test solution was also monitored during the entire period of immersion. The left over nickel ions present in the test solution after completion of immersion was also estimated using Atomic Absorption Spectrophotometer. The surface morphology of the corroded steel surface was also examined using scanning electron microscopy (SEM. The results of the studies show that SS 304L largely remains unaffected in both distilled water and artificial seawater under different experimental conditions. However, the effect of nickel on the corrosion behavior of mild steel is quite pronounced and follows interesting trends.

Electrochemical studies of the corrosion behavior of a low-carbon steel in aqueous chloride solutions simulating accident conditions of radioactive waste disposal

International Nuclear Information System (INIS)

Farvaque-Bera, A.M.; Leistikow, S.

1991-01-01

The fine-grained structural steel DIN W.Nr. 1.0566 was exposed to various sulfate and chloride-containing aqueous solutions, the latter ones simulating the potential accidental environment of water intrusion into a salt mine. By electrochemical measurements in salt brines, the following results were achieved: (1) The corrosion rate is highly dependent on salt brine composition, pH and temperature. (2) Active metal dissolution led to formation of shallow pits as surface corrosion phenomenon. Thus, the application of electrochemical techniques - under non-polarized as well as under potentiodynamic conditions - proved to be suitable for fast qualitative testing of the influence of various environmental parameters on steel corrosion. (orig.)

Corrosion behavior of Al6061 alloy weldment produced by friction stir welding process

Directory of Open Access Journals (Sweden)

Farhad Gharavi

2015-07-01

Full Text Available In this work, the corrosion behavior of welded lap joints of AA6061-T6 aluminum alloy produced by friction stir welding process has been investigated. Corrosion properties of welded lap joints were studied by cyclic polarization and electrochemical impedance spectroscopy tests. All tests were performed in an aerated 0.6 mol L−1 NaCl aqueous solution with pH = 6.5 at a temperature of 30 °C to characterize corrosion morphology and realize corrosion features of weld regions as opposed to the parent alloy. The microstructure of weld nugget (WN, heated affected zone (HAZ, and parent alloy were analyzed using scanning electron microscopy and energy dispersive spectroscopy. The experimental results indicated that the welding process has a major effect on the corrosion resistance, which possibly associated to the break-down and dissolution of intermetallic particles. It is supposed that an increasing in intermetallic distributed throughout the matrix of weld regions increases the galvanic corrosion couples. Furthermore, by decreasing the grain size in the weld regions, the susceptibility to corrosion is enhanced. The pitting corrosion and intergranular attack are the dominant corrosion types in the weld regions and the parent alloy.

Corrosion resistance and durability of superhydrophobic surface formed on magnesium alloy coated with nanostructured cerium oxide film and fluoroalkylsilane molecules in corrosive NaCl aqueous solution.

Science.gov (United States)

Ishizaki, Takahiro; Masuda, Yoshitake; Sakamoto, Michiru

2011-04-19

The corrosion resistant performance and durability of the superhydrophobic surface on magnesium alloy coated with nanostructured cerium oxide film and fluoroalkylsilane molecules in corrosive NaCl aqueous solution were investigated using electrochemical and contact angle measurements. The durability of the superhydrophobic surface in corrosive 5 wt% NaCl aqueous solution was elucidated. The corrosion resistant performance of the superhydrophobic surface formed on magnesium alloy was estimated by electrochemical impedance spectroscopy (EIS) measurements. The EIS measurements and appropriate equivalent circuit models revealed that the superhydrophobic surface considerably improved the corrosion resistant performance of magnesium alloy AZ31. American Society for Testing and Materials (ASTM) standard D 3359-02 cross cut tape test was performed to investigate the adhesion of the superhydrophobic film to the magnesium alloy surface. The corrosion formation mechanism of the superhydrophobic surface formed on the magnesium alloy was also proposed. © 2011 American Chemical Society

Monitoring corrosion and chemistry phenomena in supercritical aqueous systems

International Nuclear Information System (INIS)

Macdonald, D.D.; Pang, J.; Liu, C.; Kriksunov, L.; Medina, E.; Villa, J.; Bueno, J.

1994-01-01

The in situ monitoring of the chemistry and electrochemistry of aqueous heat transport fluids in thermal (nuclear and fossil) power plants is now considered essential if adequate assessment and close control of corrosion and mass transfer phenomena are to be achieved. Because of the elevated temperatures and pressures involved. new sensor technologies are required that are able to measure key parameters under plant operating conditions for extended periods of time. In this paper, the authors outline a research and development program that is designed to develop practical sensors for use in thermal power plants. The current emphasis is on sensors for measuring corrosion potential, pH, the concentrations of oxygen and hydrogen, and the electrochemical noise generated by corrosion processes at temperatures ranging from ∼250 C to 500 C. The program is currently at the laboratory stage, but testing of prototype sensors in a coal-fired supercritical power plant in Spain will begin shortly

Some problems on the aqueous corrosion of structural materials in nuclear engineering

International Nuclear Information System (INIS)

Coriou, H.; Grall, L.

1964-01-01

The purpose of this report is to give a comprehensive view of some aqueous corrosion studies which have been carried out with various materials for utilization either in nuclear reactors or in irradiated fuel treatment plants. The various subjects are listed below. Austenitic Fe-Ni-Cr alloys: the behaviour of austenitic Fe-Ni-Cr alloys in nitric medium and in the presence of hexavalent chromium; the stress corrosion of austenitic alloys in alkaline media at high temperatures; the stress corrosion of austenitic Fe-Ni-Cr alloys in 650 C steam. Ferritic steels: corrosion of low alloy steels in water at 25 and 360 C; zirconium alloys; the behaviour of ultrapure zirconium in water and steam at high temperature. (authors) [fr

The corrosion behavior of DWPF glasses

International Nuclear Information System (INIS)

Ebert, W.L.; Bates, J.K.

1995-01-01

The authors analyzed the corroded surfaces of reference glasses developed for the Defense Waste Processing Facility (DWPF) to characterize their corrosion behavior. The corrosion mechanism of nuclear waste glasses must be known in order to provide source terms describing radionuclide release for performance assessment calculations. Different DWPF reference glasses were corroded under conditions that highlighted various aspects of the corrosion process and led to different extents of corrosion. The glasses corroded by similar mechanisms, and a phenomenological description of their corrosion behavior is presented here. The initial leaching of soluble glass components results in the formation of an amorphous gel layer on the glass surface. The gel layer is a transient phase that transforms into a layer of clay crystallites, which equilibrates with the solution as corrosion continues. The clay layer does not act as a barrier to either water penetration or glass dissolution, which continues beneath it, and may eventually separate from the glass. Solubility limits for glass components may be established by the eventual precipitation of secondary phases; thus, corrosion of the glass becomes controlled by the chemical equilibrium between the solution and the assemblage of secondary phases. In effect, the solution is an intermediate phase through which the glass transforms to an energetically more favorable assemblage of phases. Implications regarding the prediction of long-term glass corrosion behavior are discussed

Influence of Hydrostatic Pressure on the Corrosion Behavior of Superhydrophobic Surfaces on Bare and Oxidized Aluminum Substrates.

Science.gov (United States)

Ou, J F; Fang, X Z; Zhao, W J; Lei, S; Xue, M S; Wang, F J; Li, C Q; Lu, Y L; Li, W

2018-05-22

It is generally recognized that superhydrophobic surfaces in water may be used for corrosion resistance due to the entrapped air in the solid/liquid interface and could find potential applications in the protection of ship hull. For a superhydrophobic surface, as its immersion depth into water increases, the resultant hydrostatic pressure is also increased, and the entrapped air can be squeezed out much more easily. It is therefore predicted that high hydrostatic pressure would cause an unexpected decrease in corrosion resistance for the vessels in deep water (e.g., submarines) because of the unstable entrapped air. In this work, in order to clarify the role of hydrostatic pressure in the corrosion behavior of superhydrophobic surfaces, two typical superhydrophobic surfaces (SHSs) were prepared on bare and oxidized aluminum substrates, respectively, and then were immersed into the NaCl aqueous solutions with different depths of ∼0 cm (hydrostatic pressure ∼0 kPa), 10 cm (1 kPa), and 150 cm (15 kPa). It was found out for the SHSs on the oxidized Al, as the hydrostatic pressure increased, the corrosion behavior became severe. However, for the SHSs on the bare Al, their corrosion behavior was complex due to hydrostatic pressure. It was found that the corrosion resistance under 1 kPa was the highest. Further mechanism analysis revealed that this alleviated corrosion behavior under 1 kPa resulted from suppressing the oxygen diffusion through the liquid and reducing the subsequent corrosion rate as compared with 0 kPa, whereas the relatively low hydrostatic pressure (HP) could stabilize the entrapped air and hence enhance the corrosion resistance, compared with 15 kPa. The present study therefore provided a fundamental understanding for the applications of SHSs to prevent the corrosion, especially for various vessels in deep water.

High temperature aqueous stress corrosion testing device

International Nuclear Information System (INIS)

Bornstein, A.N.; Indig, M.E.

1975-01-01

A description is given of a device for stressing tensile samples contained within a high temperature, high pressure aqueous environment, thereby permitting determination of stress corrosion susceptibility of materials in a simple way. The stressing device couples an external piston to an internal tensile sample via a pull rod, with stresses being applied to the sample by pressurizing the piston. The device contains a fitting/seal arrangement including Teflon and weld seals which allow sealing of the internal system pressure and the external piston pressure. The fitting/seal arrangement allows free movement of the pull rod and the piston

Corrosion-Resistant High-Entropy Alloys: A Review

Directory of Open Access Journals (Sweden)

Yunzhu Shi

2017-02-01

Full Text Available Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods on the corrosion resistance are analyzed in detail. Furthermore, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.

Investigation on localized corrosion of 304 stainless steel joints brazed using Sn-plated Ag alloy filler in NaCl aqueous solution

Science.gov (United States)

Wang, Xingxing; Li, Shuai; Peng, Jin

2018-03-01

Novel AgCuZnSn filler metal with high Sn contents was prepared from BAg50CuZn filler metal by a process of electroplating and thermal diffusion, and the prepared filler metal was applied to induction brazing of 304 stainless steel. The corrosion behavior of the brazed joints was evaluated based on localized corrosion analysis, the morphology of the joints were analyzed by SEM after immersion in a 3.5 vol% NaCl aqueous solution. The results indicated that corrosion groove occurred near the interface between the stainless steel base metal and the brazing seam. A wide range of defects such as holes and cracks appeared on the surface of the base metal, while the brazing seam zone almost no corrosion defects occur. With the increase of corrosion time, the corrosion rates of both the brazing seam and the base metal first exhibited an increasing trend, followed by a decreasing trend, and the corrosion rate of the base metal was slightly greater than that of the brazing seam. The corrosion potential of the brazing seam and 304 stainless steel were -0.7758 V and -0.7863 V, respectively.

Effect of pH on corrosion behavior of CuCrZr in solution without and with NaCl

Energy Technology Data Exchange (ETDEWEB)

Kwok, C.T.; Wong, P.K. [Department of Electromechanical Engineering, University of Macau (China); Man, H.C. [Department of Industrial and Systems Engineering, Hong Kong Polytechnic University (Hong Kong); Cheng, F.T., E-mail: apaftche@polyu.edu.h [Department of Applied Physics, Hong Kong Polytechnic University (Hong Kong)

2009-10-01

CuCrZr is a high copper alloy widely used as electrical and thermal conducting material, especially in heat exchangers in nuclear reactors. In this respect, the physical and fatigue properties of CuCrZr have been extensively studied. The electrochemical behavior of CuCrZr, on the other hand, has not been adequately investigated. In the present study, the effect of pH on the corrosion behavior of CuCrZr in aqueous solutions without and with chloride (0.6 M NaCl) was studied. The pH of the solutions is found to exert significant influence on the corrosion behavior of CuCrZr. In acidic solutions without chloride, the corrosion of CuCrZr is ascribed to active dissolution with soluble products. In neutral and alkaline solutions without NaCl, the presence of oxides on the surface of CuCrZr leads to a noble shift in corrosion potential and passivation results in increased corrosion resistance. In chloride solutions at various pH values, the chloride ions influence the formation of the surface layers and the anodic dissolution process during polarization. At high pH, CuCrZr shows significant passivity and high corrosion resistance due to the growth of Cu{sub 2}O/Cu(OH) film which hinders further dissolution whereas at low pH the corrosion resistance is lowered due to active dissolution of Cu.

Effect of pH on corrosion behavior of CuCrZr in solution without and with NaCl

International Nuclear Information System (INIS)

Kwok, C.T.; Wong, P.K.; Man, H.C.; Cheng, F.T.

2009-01-01

CuCrZr is a high copper alloy widely used as electrical and thermal conducting material, especially in heat exchangers in nuclear reactors. In this respect, the physical and fatigue properties of CuCrZr have been extensively studied. The electrochemical behavior of CuCrZr, on the other hand, has not been adequately investigated. In the present study, the effect of pH on the corrosion behavior of CuCrZr in aqueous solutions without and with chloride (0.6 M NaCl) was studied. The pH of the solutions is found to exert significant influence on the corrosion behavior of CuCrZr. In acidic solutions without chloride, the corrosion of CuCrZr is ascribed to active dissolution with soluble products. In neutral and alkaline solutions without NaCl, the presence of oxides on the surface of CuCrZr leads to a noble shift in corrosion potential and passivation results in increased corrosion resistance. In chloride solutions at various pH values, the chloride ions influence the formation of the surface layers and the anodic dissolution process during polarization. At high pH, CuCrZr shows significant passivity and high corrosion resistance due to the growth of Cu 2 O/Cu(OH) film which hinders further dissolution whereas at low pH the corrosion resistance is lowered due to active dissolution of Cu.

Characterisation of the aqueous corrosion process in NdFeB melt spun ribbon and MQI bonded magnets

Science.gov (United States)

McCain, Stephen

A major factor limiting the use and longevity of rare earth based magnetic materials is their susceptibility to aqueous corrosion and associated detrimental effects upon the magnetic properties of the material. This process was investigated through a combination of exposure to simulated environmental conditions and hydrogen absorption/desorption studies (HADS) in conjunction with magnetic characterisation. This study utilises NdFeB MQP-B melt-spun ribbon manufactured by Magnequench, in the form of MQI bonded magnets and also in its unbonded state as MQ powder. Specifically, it was concerned with how effective a variety of bonding media (epoxy resin,PTFE, zinc) and surface coatings (PTFE, Qsil, zinc LPPS, Dex-Cool) were at limiting the impact of aqueous corrosion in MQI bonded magnets. To characterise the effect of hydrogen absorption upon the magnetic properties of the MQP-B, hydrogen uptake was induced followed by a series of outgassing heat treatments with subsequent magnetic characterisation accompanied by HADS techniques performed after each outgas. This allowed comparisons to be made between the effects of aqueous corrosion process and hydrogen absorption upon the magnetic properties of the alloy.. This study has clearly demonstrated the link between the abundance of environmental moisture and rate of Hci losses in MQI bonded magnets. In addition to this the key mechanism responsible for the degradation of magnetic properties has been identified. These losses have been attributed to the absorption of hydrogen generated by the dissociation of water in the presence of NdFeB during the aqueous corrosion process. It has been shown that the use of a bonding media that is impermeable to water can limit the effects of aqueous corrosion by limiting water access to the Magnequench particles (MQP) and also the positive effects of the use of suitable surface coatings has been shown to be effective for the same reason..

The aqueous corrosion behavior of technetium - Alloy and composite materials

International Nuclear Information System (INIS)

Jarvinen, G.; Kolman, D.; Taylor, C.; Goff, G.; Cisneros, M.; Mausolf, E.; Poineau, F.; Koury, D.; Czerwinski, K.

2013-01-01

Metal waste forms are under study as possible disposal forms for technetium and other fission products. The alloying of Tc is desirable to reduce the melting point of the Tc-containing metal waste form and potentially improve its corrosion resistance. Technetium-nickel composites were made by mixing the two metal powders and pressing the mixture to make a pellet. The as-pressed composite materials were compared to sintered composites and alloys of identical composition in electrochemical corrosion tests. As-pressed samples were not robust enough for fine polishing and only a limited number of corrosion tests were performed. Alloys and composites with 10 wt% Tc appear to be more corrosion resistant at open circuit than the individual components based on linear polarization resistance and polarization data. The addition of 10 wt% Tc to Ni appears beneficial at open circuit, but detrimental upon anodic polarization. Qualitatively, the polarizations of 10 wt% Tc alloys and composites appear like crude addition of Tc plus Ni. The 1 wt% Tc alloys behave like pure Ni, but some effect of Tc is seen upon polarization. Cathodic polarization of Tc by Ni appears feasible based on open circuit potential measurements, however, zero resistance ammetry and solution measurements are necessary to confirm cathodic protection

The aqueous corrosion behavior of technetium - Alloy and composite materials

Energy Technology Data Exchange (ETDEWEB)

Jarvinen, G.; Kolman, D.; Taylor, C.; Goff, G.; Cisneros, M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Mausolf, E.; Poineau, F.; Koury, D.; Czerwinski, K. [Department of Chemistry, University of Nevada, Las Vegas, Las Vegas, NV 89154 (United States)

2013-07-01

Metal waste forms are under study as possible disposal forms for technetium and other fission products. The alloying of Tc is desirable to reduce the melting point of the Tc-containing metal waste form and potentially improve its corrosion resistance. Technetium-nickel composites were made by mixing the two metal powders and pressing the mixture to make a pellet. The as-pressed composite materials were compared to sintered composites and alloys of identical composition in electrochemical corrosion tests. As-pressed samples were not robust enough for fine polishing and only a limited number of corrosion tests were performed. Alloys and composites with 10 wt% Tc appear to be more corrosion resistant at open circuit than the individual components based on linear polarization resistance and polarization data. The addition of 10 wt% Tc to Ni appears beneficial at open circuit, but detrimental upon anodic polarization. Qualitatively, the polarizations of 10 wt% Tc alloys and composites appear like crude addition of Tc plus Ni. The 1 wt% Tc alloys behave like pure Ni, but some effect of Tc is seen upon polarization. Cathodic polarization of Tc by Ni appears feasible based on open circuit potential measurements, however, zero resistance ammetry and solution measurements are necessary to confirm cathodic protection.

High corrosion resistance of magnesium coated with hydroxyapatite directly synthesized in an aqueous solution

International Nuclear Information System (INIS)

Hiromoto, Sachiko; Yamamoto, Akiko

2009-01-01

Anticorrosion coatings are crucial for practical applications of magnesium alloys, which are used to reduce the weight of vehicles, aircraft, electronics enclosures etc. Hydroxyapatite (HAp) potentially offers high corrosion resistance and no environmental toxicity because its thermodynamic structural stability is high and it is a basic component of bone. However, direct synthesis of HAp on magnesium in aqueous solutions has been a scientific challenge because Mg ions prevent HAp crystallization. A new method of direct synthesis of HAp on magnesium was developed using a Ca chelate compound, which can maintain a sufficiently high concentration of Ca ions on the magnesium surface to overcome prevention of HAp crystallization with Mg ions. Highly crystallized HAp coatings were successfully formed on pure magnesium and AZ series alloys. Corrosion behavior of HAp-coated pure magnesium was examined by cyclic dry and wet tests with 1 g m -2 NaCl on the surface and polarization tests in a 3.5 wt% NaCl solution. A HAp-coated pure magnesium showed no noticeable corrosion pits after the dry and wet test. HAp-coated specimens showed 10 3 -10 4 times lower anodic current density than as-polished specimen in the polarization test. The results demonstrate the remarkable anticorrosion performance of HAp coatings on magnesium for the first time.

Effects of 1000 C oxide surfaces on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

Energy Technology Data Exchange (ETDEWEB)

Buchanan, R.A.; Perrin, R.L. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering

1997-12-01

Results of electrochemical aqueous-corrosion studies at room temperature indicate that retained in-service-type high-temperature surface oxides (1000 C in air for 24 hours) on FA-129, FAL and FAL-Mo iron aluminides cause major reductions in pitting corrosion resistance in a mild acid-chloride solution designed to simulate aggressive atmospheric corrosion. Removal of the oxides by mechanical grinding restores the corrosion resistance. In a more aggressive sodium tetrathionate solution, designed to simulate an aqueous environment contaminated by sulfur-bearing combustion products, only active corrosion occurs for both the 1000 C oxide and mechanically cleaned surfaces at FAL. Results of slow-strain-rate stress-corrosion-cracking tests on FA-129, FAL and FAL-Mo at free-corrosion and hydrogen-charging potentials in the mild acid chloride solution indicate somewhat higher ductilities (on the order of 50%) for the 1000 C oxides retard the penetration of hydrogen into the metal substrates and, consequently, are beneficial in terms of improving resistance to environmental embrittlement. In the aggressive sodium tetrathionate solution, no differences are observed in the ductilities produced by the 1000 C oxide and mechanically cleaned surfaces for FAL.

Effect of geologic repository parameters on aqueous corrosion of nuclear glass

International Nuclear Information System (INIS)

Tovena, I.; Advocat, T.; Jollivet, P.; Godon, N.; Vernaz, E.

1995-01-01

Twenty alumino-borosilicate glass compositions containing simulated fission product oxides were defined using the experimentation plan methodology. Three additional glass compositions were also tested. Monolithic glass corrosion tests in a dilute aqueous medium at 90 deg C indicated the variation range for the initial corrosion rates. Significant but only qualitative correlations were established between the initial corrosion rate and the molar fraction of glass network forming oxides (SiO 2 + Al 2 O 3 ), and between the initial rate and the (Na 2 O + Li 2 O + B 2 O 3 ) / (SiO 2 + Al 2 O 3 ) molar ratio in the glass. The experimentation plan allowed a polynomial model to be defined relating the initial corrosion rate at 90 deg C to the oxide concentrations in the glass. Although the model is theoretically capable of predicting the corrosion rates, it does not always account for the actual data measured during other experiments; this discrepancy may be attributable either to the presence of other chemical elements (MgO) or to CaO concentrations differing from the fixed value adopted for the experimentation plan. Glass powder corrosion tests designed to simulate advanced corrosion reaction progress, account for the wide variations in the dissolved glass quantities, although no correlation exists with the glass chemical composition. (authors). 49 refs., 4 figs., 34 tabs

Effect of geologic repository parameters on aqueous corrosion of nuclear glass

Energy Technology Data Exchange (ETDEWEB)

Tovena, I; Advocat, T; Jollivet, P; Godon, N; Vernaz, E

1996-12-31

Twenty alumino-borosilicate glass compositions containing simulated fission product oxides were defined using the experimentation plan methodology. Three additional glass compositions were also tested. Monolithic glass corrosion tests in a dilute aqueous medium at 90 deg C indicated the variation range for the initial corrosion rates. Significant but only qualitative correlations were established between the initial corrosion rate and the molar fraction of glass network forming oxides (SiO{sub 2} + Al{sub 2}O{sub 3}), and between the initial rate and the (Na{sub 2}O + Li{sub 2}O + B{sub 2}O{sub 3}) / (SiO{sub 2} + Al{sub 2}O{sub 3}) molar ratio in the glass. The experimentation plan allowed a polynomial model to be defined relating the initial corrosion rate at 90 deg C to the oxide concentrations in the glass. Although the model is theoretically capable of predicting the corrosion rates, it does not always account for the actual data measured during other experiments; this discrepancy may be attributable either to the presence of other chemical elements (MgO) or to CaO concentrations differing from the fixed value adopted for the experimentation plan. Glass powder corrosion tests designed to simulate advanced corrosion reaction progress, account for the wide variations in the dissolved glass quantities, although no correlation exists with the glass chemical composition. (authors). 49 refs., 4 figs., 34 tabs.

Influence of chloride ion concentration on the corrosion behavior of Al-bearing TRIP steels

Energy Technology Data Exchange (ETDEWEB)

El-Taib Heakal, F., E-mail: fakihaheakal@yahoo.com [Chemistry Department, Faculty of Science, Cairo University, Giza 12613 (Egypt); Tantawy, N.S. [Chemistry Department, Girl' s College for Arts, Science and Education, Ain Shams University, Cairo (Egypt); Shehta, O.S. [Physical Chemistry Department, National Research Centre, Dokki, Giza (Egypt)

2011-10-17

Highlights: {yields} Systematic increase of chloride concentration has a critical influence on TRIP steel corrosion. {yields} TRIP microalloyed with Nb and Cr showed lower corrosion rate and smaller threshold Cl{sup -} value. {yields} Increasing Al content by 220 times in the TRIP deteriorates its corrosion behavior. {yields} Impedance results and surface examinations confirmed the obtained results. - Abstract: The effect of a systematic increase of chloride ion concentration on the electrochemical corrosion behavior of two types of Al-bearing TRIP steels (T{sub 1} and T{sub 2}) was studied in aqueous NaCl solutions. Several electrochemical techniques were used comprising open circuit potential measurements, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Chloride concentration has a critical influence on the corrosion rate of the two tested steel samples. For both steels the corrosion rate first increased with increasing chloride content up to a certain critical concentration (CC), and then decreased in solution with chloride level higher than the threshold value. TRIP steel T{sub 1} microalloyed with Nb and Cr as compared to steel T{sub 2} not containing these two elements, exhibited lower corrosion rate and smaller CC value, indicating better corrosion resistance to chloride attack, albeit the Al content in T{sub 2} is 220 times higher than that in T{sub 1}. This is because Nb alloyed with TRIP steel likely enhances the formation on the surface of a stable rust layer enriched with other passivating elements Al, Cu, Cr and Ni, which has higher corrosion resistance and hence improve greatly the passive performance of the TRIP sample. The ac impedance data are in good agreement with the OCP and dc polarization measurements. Surface examinations via scanning electron microscope confirmed well the obtained results.

Influence of chloride ion concentration on the corrosion behavior of Al-bearing TRIP steels

International Nuclear Information System (INIS)

El-Taib Heakal, F.; Tantawy, N.S.; Shehta, O.S.

2011-01-01

Highlights: → Systematic increase of chloride concentration has a critical influence on TRIP steel corrosion. → TRIP microalloyed with Nb and Cr showed lower corrosion rate and smaller threshold Cl - value. → Increasing Al content by 220 times in the TRIP deteriorates its corrosion behavior. → Impedance results and surface examinations confirmed the obtained results. - Abstract: The effect of a systematic increase of chloride ion concentration on the electrochemical corrosion behavior of two types of Al-bearing TRIP steels (T 1 and T 2 ) was studied in aqueous NaCl solutions. Several electrochemical techniques were used comprising open circuit potential measurements, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Chloride concentration has a critical influence on the corrosion rate of the two tested steel samples. For both steels the corrosion rate first increased with increasing chloride content up to a certain critical concentration (CC), and then decreased in solution with chloride level higher than the threshold value. TRIP steel T 1 microalloyed with Nb and Cr as compared to steel T 2 not containing these two elements, exhibited lower corrosion rate and smaller CC value, indicating better corrosion resistance to chloride attack, albeit the Al content in T 2 is 220 times higher than that in T 1 . This is because Nb alloyed with TRIP steel likely enhances the formation on the surface of a stable rust layer enriched with other passivating elements Al, Cu, Cr and Ni, which has higher corrosion resistance and hence improve greatly the passive performance of the TRIP sample. The ac impedance data are in good agreement with the OCP and dc polarization measurements. Surface examinations via scanning electron microscope confirmed well the obtained results.

The corrosion rate and the hydrogen absorption behavior of titanium under reducing condition-III. Research document

International Nuclear Information System (INIS)

Suzuki, H.; Taniguchi, N.; Kawakami, S.

2005-03-01

Titanium is one of the candidate materials for overpacks as a high corrosion resistance metal. At the initial stage of repository, oxidizing condition will be given around the overpack because oxygen will be brought from the ground. The oxygen will be consumed by the reaction with impurities in buffer material or corrosion of overpack, and reducing condition will be achieved around the overpack. With the changing of redox condition, the water reduction becomes to dominate the cathodic reaction accompanying hydrogen generation. Crevice corrosion and hydrogen embrittlement are main causes of the damage of long term integrity of titanium overpack. However, it is not known about the corrosion resistance and hydrogen absorption behavior of titanium under reduction condition. In this study, the completely sealed ampoule test and the immersion test of titanium in aqueous solution and bentonite was carried out. In order to obtain reliable data about the hydrogen generation rate and the ratio of hydrogen absorption in titanium. From the result of 3 years immersion tests, corrosion rate of titanium were estimated to be in the order of 10 -2 ∼10 -1 μm/y in the aqueous solution, and 10 -3 ∼10 -2 μm/y in bentonite. This value is almost the same as the last report. Almost all the hydrogen generated by corrosion was absorbed in titanium in the immersion tests in completely sealed ampoule. In the examination that changed each parameter, it was suggested that the amount of the hydrogen absorption become 2∼3 times in 1M HCO 3- and pH13. (author)

An example of transition from a corrosion process in gaseous phase to corrosion in aqueous environment: the case of Z2CN18-10 stainless steel by iodine and water in vapour phase

International Nuclear Information System (INIS)

Mathieu, Bruno

1990-01-01

This research thesis addresses an example of transition of a corrosion process in gaseous phase towards corrosion in aqueous environment, specifically in the case of the corrosion of the Z2CN18-10 stainless steel by gaseous iodine in presence of water vapour (and possibly nitrogen dioxide). This transition occurs in two steps: initiation in gaseous phase and growth in aqueous environment. This transition is due to hygroscopic properties of mostly chromium iodides and, to a lesser extent, iron iodides. Morphological, electrochemical and thermogravimetry studies have been performed by varying different parameters governing corrosion processes: corrosion temperature, iodine concentration, relative humidity, and reaction time [fr

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.

Corrosion behavior of 316 L stainless steel simulated by studying the influence of the species produced in the radiolysis in tritiated aqueous solutions

International Nuclear Information System (INIS)

Bellanger, G.

1991-10-01

The corrosion of 316 L stainless steel in tritiated aqueous solutions was simulated by studying the influence of species produced or present in the radiolysis in these solutions. The species studied were nitrates, fluorides, nitrites, hydrogen peroxide and components of the steel, as well as the pH. The method used was voltammetry. The corroded or passivated surfaces were examined by scanning electron microscopy and the corrosion rates were determined by measuring the electrochemical impedance. The depletion of the component elements of the stainless steel at the surface was observed by X-ray fluorescence. From our results we propose methods to limit the corrosion in an industrial tritiated water installation by controlling the pH, the oxidation-reduction potential of the water and the voltage of the installation [fr

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.

High corrosion resistance of magnesium coated with hydroxyapatite directly synthesized in an aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Hiromoto, Sachiko [Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)], E-mail: hiromoto.sachiko@nims.go.jp; Yamamoto, Akiko [Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)

2009-11-30

Anticorrosion coatings are crucial for practical applications of magnesium alloys, which are used to reduce the weight of vehicles, aircraft, electronics enclosures etc. Hydroxyapatite (HAp) potentially offers high corrosion resistance and no environmental toxicity because its thermodynamic structural stability is high and it is a basic component of bone. However, direct synthesis of HAp on magnesium in aqueous solutions has been a scientific challenge because Mg ions prevent HAp crystallization. A new method of direct synthesis of HAp on magnesium was developed using a Ca chelate compound, which can maintain a sufficiently high concentration of Ca ions on the magnesium surface to overcome prevention of HAp crystallization with Mg ions. Highly crystallized HAp coatings were successfully formed on pure magnesium and AZ series alloys. Corrosion behavior of HAp-coated pure magnesium was examined by cyclic dry and wet tests with 1 g m{sup -2} NaCl on the surface and polarization tests in a 3.5 wt% NaCl solution. A HAp-coated pure magnesium showed no noticeable corrosion pits after the dry and wet test. HAp-coated specimens showed 10{sup 3}-10{sup 4} times lower anodic current density than as-polished specimen in the polarization test. The results demonstrate the remarkable anticorrosion performance of HAp coatings on magnesium for the first time.

Microstructural characterization and electrochemical corrosion behavior of Incoloy 800 in sulphate and chloride solutions

International Nuclear Information System (INIS)

Mansur, Fabio Abud; Schvartzman, Monica Maria de Abreu Mendonca; Campos, Wagner Reis da Costa; Aguiar, Antonio Eugenio de; Chaim, Marcos Souza

2011-01-01

Corrosion has been the major cause of tube failures in steam generators (SG) tubes in nuclear power plants. Problems have resulted from impurities in the secondary water systems which are originated from leaks of cooling water. It is important to understand the compatibility of steam generator tube materials with the environment. This study presents the microstructural characterization and electrochemical behavior of the Incoloy 800 in sodium chloride and sodium sulphate aqueous solutions at 80 degree C. Potentiodynamic anodic polarization, cyclic polarization and open circuit potential (OCP) measurements were the electrochemical techniques applied in this work. The pitting resistance of Incoloy 800 in chloride plus sulphate mixtures were also examined. Experiments performed in solutions with different concentrations of Cl- and SO 4 2- ions in solution (200 ppb, 500 ppb, 1ppm, 5 ppm, 50 ppm and 100 ppm) showed that this concentrations range had no substantial effect on the anodic behavior of the alloy. After polarization no localized corrosion was found on the samples. (author)

Effects of high temperature surface oxides on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

Energy Technology Data Exchange (ETDEWEB)

Buchanan, R.A.; Perrin, R.L.

1996-09-01

Studies were conducted to determine the effects of high-temperature surface oxides, produced during thermomechanical processing, heat treatment (750 {degrees}C in air, one hour) or simulated in-service-type oxidation (1000{degrees}C in air, 24 hours) on the room-temperature aqueous-corrosion and environmental-embrittlement characteristics of iron aluminides. Materials evaluated included the Fe{sub 3}Al-based iron aluminides, FA-84, FA-129, FAL and FAL-Mo, a FeAl-based iron aluminide, FA-385, and a disordered low-aluminum Fe-Al alloy, FAPY. Tests were performed in a mild acid-chloride solution to simulate aggressive atmospheric corrosion. Cyclic-anodic-polarization tests were employed to evaluate resistances to localized aqueous corrosion. The high-temperature oxide surfaces consistently produced detrimental results relative to mechanically or chemically cleaned surfaces. Specifically, the pitting corrosion resistances were much lower for the as-processed and 750{degrees} C surfaces, relative to the cleaned surfaces, for FA-84, FA-129, FAL-Mo, FA-385 and FAPY. Furthermore, the pitting corrosion resistances were much lower for the 1000{degrees}C surfaces, relative to cleaned surfaces, for FA-129, FAL and FAL-Mo.

Flow-induced corrosion behavior of absorbable magnesium-based stents.

Science.gov (United States)

Wang, Juan; Giridharan, Venkataraman; Shanov, Vesselin; Xu, Zhigang; Collins, Boyce; White, Leon; Jang, Yongseok; Sankar, Jagannathan; Huang, Nan; Yun, Yeoheung

2014-12-01

The aim of this work was to study corrosion behavior of magnesium (Mg) alloys (MgZnCa plates and AZ31 stents) under varied fluid flow conditions representative of the vascular environment. Experiments revealed that fluid hydrodynamics, fluid flow velocity and shear stress play essential roles in the corrosion behavior of absorbable magnesium-based stent devices. Flow-induced shear stress (FISS) accelerates the overall corrosion (including localized, uniform, pitting and erosion corrosions) due to the increased mass transfer and mechanical force. FISS increased the average uniform corrosion rate, the localized corrosion coverage ratios and depths and the removal rate of corrosion products inside the corrosion pits. For MgZnCa plates, an increase of FISS results in an increased pitting factor but saturates at an FISS of ∼0.15Pa. For AZ31 stents, the volume loss ratio (31%) at 0.056Pa was nearly twice that (17%) at 0Pa before and after corrosion. Flow direction has a significant impact on corrosion behavior as more severe pitting and erosion corrosion was observed on the back ends of the MgZnCa plates, and the corrosion product layer facing the flow direction peeled off from the AZ31 stent struts. This study demonstrates that flow-induced corrosion needs be understood so that Mg-based stents in vascular environments can be effectively designed. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Suppression of aqueous corrosion of La(Fe0.88Si0.12)13 by reducing dissolved oxygen concentration for high-performance magnetic refrigeration

International Nuclear Information System (INIS)

Fujieda, S.; Fukamichi, K.; Suzuki, S.

2014-01-01

Highlights: • The aqueous corrosion of La(Fe 0.88 Si 0.12 ) 13 and its suppression were investigated. • The lattice expansion after immersion was caused by the hydrogen absorption. • The itinerant-electron metamagnetic transition became indistinct after immersion. • The aqueous corrosion was suppressed by reducing the dissolved oxygen concentration. - Abstract: The itinerant-electron metamagnetic transition of La(Fe 0.88 Si 0.12 ) 13 becomes indistinct after immersion in distilled-water containing about 8 ppm of the dissolved oxygen (DO) concentration because of aqueous corrosion. However, the aqueous corrosion of La(Fe 0.88 Si 0.12 ) 13 is significantly suppressed by reducing the DO concentration. Thus, isothermal magnetic entropy change after immersion for 30 days in deaerated distilled-water with a DO concentration less than 0.1 ppm is larger than that after immersion for 5 days in distilled-water containing about 8 ppm of the DO concentration. Consequently, the reduction of the DO concentration is effective for preservation of the excellent magnetocaloric effects of La(Fe 0.88 Si 0.12 ) 13 in an aqueous solution, which is a promising heat transfer fluid of room-temperature magnetic refrigeration

Corrosion characteristics and oxide microstructures of Zircaloy-4 in aqueous alkali hydroxide solutions

International Nuclear Information System (INIS)

Jeong, Y.H.; Baek, J.H.; Kim, S.J.; Kim, H.G.

1999-01-01

The corrosion characteristics of Zircaloy-4 have been investigated in various aqueous solutions of LiOH, NaOH, KOH, RbOH and CsOH with equimolar M + and OH - at 350 C. The characterization of the oxides was performed using transmission electron microscope (TEM) and scanning electron microscope (SEM) on the samples which were prepared to have an equal oxide thickness in pre-transition and post-transition regimes. At a low concentration (4.3 mmol) of aqueous alkali hydroxide solutions, the corrosion rates decrease gradually as the ionic radius of cation increases. At a high concentration (32.5 mmol), the corrosion rate increases significantly in LiOH solution and slightly in NaOH solution, but in the other hydroxide solutions such as KOH, RbOH and CsOH, the corrosion rate is not accelerated. Even if the specimens have an equal oxide thickness in LiOH, NaOH and KOH solutions, the oxide microstructure formed in the LiOH solution is quite different from those formed in the NaOH or the KOH solutions. In the LiOH solution, the oxides grown in the pre-transition regime as well as in the post-transition regime have an equiaxed structure including many pores and open grain boundaries. The oxides grown in the NaOH solution have a protective columnar structure in the pre-transition regime but an equiaxed structure in the post-transition regime. On the other hand, in the KOH solution, the columnar structure is maintained from its pre-transition regime to the post-transition regime. On the basis of the above results, it can be suggested that the cation incorporation into zirconium oxide would control the oxide microstructure, the oxide growth mechanism at the metal-oxide interface and the corrosion rate in alkali hydroxide solutions. (orig.)

Corrosion behavior induced by LiCl-KCl in type 304 and 316 stainless steel and copper at low temperature

Energy Technology Data Exchange (ETDEWEB)

Sim, Jee Hyung; Kim, Yong Soo; Cho, Il Je [Dept. of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of)

2017-06-15

The corrosion behavior of stainless steel (304 and 316 type) and copper induced by LiCl-KCl at low temperatures in the presence of sufficient oxygen and moisture was investigated through a series of experiments (at 30°C, 40°C, 60°C, and 80°C for 24 hours, 48 hours, 72 hours, and 96 hours). The specimens not coated on one side with an aqueous solution saturated with LiCl-KCl experienced no corrosion at any temperature, not even when the test duration exceeded 96 hours. Stainless steel exposed to LiCl-KCl experienced almost no corrosion below 40°C, but pitting corrosion was observed at temperatures above 60°C. As the duration of the experiment was increased, the rate of corrosion accelerated in proportion to the temperature. The 316 type stainless steel exhibited better corrosion resistance than did the 304 type. In the case of copper, the rate of corrosion accelerated in proportion to the duration and temperature but, unlike the case of stainless steel, the corrosion was more general. As a result, the extent of copper corrosion was about three times that of stainless steel.

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

Sodium phthalamates as corrosion inhibitors for carbon steel in aqueous hydrochloric acid solution

International Nuclear Information System (INIS)

Flores, Eugenio A.; Olivares, Octavio; Likhanova, Natalya V.; Dominguez-Aguilar, Marco A.; Nava, Noel; Guzman-Lucero, Diego; Corrales, Monica

2011-01-01

Highlights: → N-Alkyl-sodium phthalamates as corrosion inhibitors for industry in acidic medium. → Compounds behaved as mixed type inhibitors and followed Langmuir adsorption isotherm. → Efficiencies were proportional to aliphatic chain length and inhibitor concentration. → Iron complexes and chelates with phthalamates contributed to carbon steel protection. - Abstract: Three compounds of N-alkyl-sodium phthalamates were synthesized and tested as corrosion inhibitors for carbon steel in 0.5 M aqueous hydrochloric acid. Tests showed that inhibitor efficiencies were related to aliphatic chain length and dependent on concentration. N-1-n-tetradecyl-sodium phthalamate displayed moderate efficiency against uniform corrosion, 42-86% at 25 deg. C and 25-60% at 40 o C. Tests indicated that compounds behave as mixed type inhibitors where molecular adsorption on steel followed Langmuir isotherm, whereas thermodynamic suggested that a physisorption process occurred. XPS analysis confirmed film formation on surface, where Fe +2 complexes and Fe +2 chelates with phthalamates prevented steel from further corrosion.

Passive Corrosion Behavior of Alloy 22

International Nuclear Information System (INIS)

R.B. Rebak; J.H. Payer

2006-01-01

Alloy 22 (NO6022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nano-meters per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids

Dealloying, Microstructure and the Corrosion/Protection of Cast Magnesium Alloys

Energy Technology Data Exchange (ETDEWEB)

Sieradzki, Karl [Arizona State Univ., Mesa, AZ (United States); Aiello, Ashlee [Arizona State Univ., Mesa, AZ (United States); McCue, Ian [Arizona State Univ., Mesa, AZ (United States)

2017-12-15

The purpose of this project was to develop a greater understanding of micro-galvanic corrosion effects in cast magnesium alloys using both experimental and computational methods. Experimental accomplishments have been made in the following areas of interest: characterization, aqueous free-corrosion, atmospheric corrosion, ionic liquid dissolution, rate kinetics of oxide dissolution, and coating investigation. Commercial alloys (AZ91D, AM60, and AZ31B), binary-phase alloys (αMg-2at.%Al, αMg-5at.%Al, and Mg-8at.%Al), and component phases (Mg, Al, β-Mg, β-1%Zn, MnAl3) were obtained and characterized using energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Full immersion in aqueous chloride was used to characterize the corrosion behavior of alloys. Rotating disc electrodes (RDEs) were used to observe accelerated long-term corrosion behavior. Al surface redistribution for freely corroded samples was analyzed using SEM, EDS, and lithium underpotential deposition (Li UPD). Atmospheric corrosion was observed using contact angle evolution, overnight pH monitoring, and surface pH evolution studies. Ionic liquid corrosion characterization was performed using linear sweep voltammetry and potentiostatic dissolution in 150° choline chloride-urea (cc-urea). Two surface coatings were investigated: (1) Li-carbonate and (2) cc-urea. Li-carbonate coatings were characterized using X-ray photoelectron spectroscopy (XPS), SEM, and aqueous free corrosion potential monitoring. Hydrophobic cc-urea coatings were characterized using contact angle measurements and electrochemical impedance spectroscopy. Oxide dissolution rate kinetics were studied using inductively coupled plasma mass spectroscopy (ICP-MS). Computational accomplishments have been made through the development of Kinetic Monte Carlo (KMC) simulations which model time- and composition-dependent effects on the microstructure due to spatial redistribution of alloying

Corrosion behavior of Ti-39Nb alloy for dentistry.

Science.gov (United States)

Fojt, Jaroslav; Joska, Ludek; Malek, Jaroslav; Sefl, Vaclav

2015-11-01

To increase an orthopedic implant's lifetime, researchers are now concerned on the development of new titanium alloys with suitable mechanical properties (low elastic modulus-high fatigue strength), corrosion resistance and good workability. Corrosion resistance of the newly developed titanium alloys should be comparable with that of pure titanium. The effect of medical preparations containing fluoride ions represents a specific problem related to the use of titanium based materials in dentistry. The aim of this study was to determine the corrosion behavior of β titanium alloy Ti-39Nb in physiological saline solution and in physiological solution containing fluoride ions. Corrosion behavior was studied using standard electrochemical techniques and X-ray photoelectron spectroscopy. It was found that corrosion properties of the studied alloy were comparable with the properties of titanium grade 2. The passive layer was based on the oxides of titanium and niobium in several oxidation states. Alloying with niobium, which was the important part of the alloy passive layer, resulted in no significant changes of corrosion behavior. In the presence of fluoride ions, the corrosion resistance was higher than the resistance of titanium. Copyright © 2015 Elsevier B.V. All rights reserved.

Corrosion behavior of Ti–39Nb alloy for dentistry

Energy Technology Data Exchange (ETDEWEB)

Fojt, Jaroslav, E-mail: fojtj@vscht.cz [Institute of Chemical Technology, Technicka 5, 166 28 Prague (Czech Republic); Joska, Ludek [Institute of Chemical Technology, Technicka 5, 166 28 Prague (Czech Republic); Malek, Jaroslav [UJP Praha, Nad Kamínkou 1345, 156 10 Prague-Zbraslav (Czech Republic); Sefl, Vaclav [Institute of Chemical Technology, Technicka 5, 166 28 Prague (Czech Republic)

2015-11-01

To increase an orthopedic implant's lifetime, researchers are now concerned on the development of new titanium alloys with suitable mechanical properties (low elastic modulus–high fatigue strength), corrosion resistance and good workability. Corrosion resistance of the newly developed titanium alloys should be comparable with that of pure titanium. The effect of medical preparations containing fluoride ions represents a specific problem related to the use of titanium based materials in dentistry. The aim of this study was to determine the corrosion behavior of β titanium alloy Ti–39Nb in physiological saline solution and in physiological solution containing fluoride ions. Corrosion behavior was studied using standard electrochemical techniques and X-ray photoelectron spectroscopy. It was found that corrosion properties of the studied alloy were comparable with the properties of titanium grade 2. The passive layer was based on the oxides of titanium and niobium in several oxidation states. Alloying with niobium, which was the important part of the alloy passive layer, resulted in no significant changes of corrosion behavior. In the presence of fluoride ions, the corrosion resistance was higher than the resistance of titanium. - Highlights: • Alloy Ti–39Nb shows excellent corrosion resistance in physiological solution. • Corrosion resistance of Ti–39Nb alloy is significantly higher than that of titanium in the presence of fluoride ions. • The electrochemical impedance spectroscopy indicates a porous passive layer. • Passive layer of the alloy is enriched by niobium.

Corrosion behavior of Ti–39Nb alloy for dentistry

International Nuclear Information System (INIS)

Fojt, Jaroslav; Joska, Ludek; Malek, Jaroslav; Sefl, Vaclav

2015-01-01

To increase an orthopedic implant's lifetime, researchers are now concerned on the development of new titanium alloys with suitable mechanical properties (low elastic modulus–high fatigue strength), corrosion resistance and good workability. Corrosion resistance of the newly developed titanium alloys should be comparable with that of pure titanium. The effect of medical preparations containing fluoride ions represents a specific problem related to the use of titanium based materials in dentistry. The aim of this study was to determine the corrosion behavior of β titanium alloy Ti–39Nb in physiological saline solution and in physiological solution containing fluoride ions. Corrosion behavior was studied using standard electrochemical techniques and X-ray photoelectron spectroscopy. It was found that corrosion properties of the studied alloy were comparable with the properties of titanium grade 2. The passive layer was based on the oxides of titanium and niobium in several oxidation states. Alloying with niobium, which was the important part of the alloy passive layer, resulted in no significant changes of corrosion behavior. In the presence of fluoride ions, the corrosion resistance was higher than the resistance of titanium. - Highlights: • Alloy Ti–39Nb shows excellent corrosion resistance in physiological solution. • Corrosion resistance of Ti–39Nb alloy is significantly higher than that of titanium in the presence of fluoride ions. • The electrochemical impedance spectroscopy indicates a porous passive layer. • Passive layer of the alloy is enriched by niobium

Study of the corrosion behavior of magnesium alloy weldings in NaCl solutions by gravimetric tests

Directory of Open Access Journals (Sweden)

Segarra, José A.

2015-09-01

Full Text Available In this article, the corrosion behavior of commercial AZ31 welded plates in aqueous chloride media was investigated by means of gravimetric techniques and Neutral Salt Spray tests (NSS. The AZ31 samples tested were welded using Gas Tugsten Arc Welding (GTAW and different filler materials. Material microstructures were investigated by optical microscopy to stablish the influence of those microstructures in the corrosion behavior. Gravimetric and NSS tests indicate that the use of more noble filler alloys for the sample welding, preventing the reduction of aluminum content in weld beads, does not imply a better corrosion behavior.En este artículo se ha investigado el comportamiento frente a la corrosión en medios acuosos salinos de chapas soldadas de aleación AZ31 mediante técnicas gravimétricas y ensayo en cámara de niebla salina. Las muestras estudiadas han sido soldadas mediante soldadura TIG (Tungsten Inert Gas y con diferentes materiales de aporte. En el estudio se ha empleado microscopía óptica para analizar la microestructura. Los ensayos de gravimetría y los ensayos de niebla salina indican que el empleo de materiales de aporte más nobles para soldar las muestras evitando la disminución del contenido en aluminio en los cordones, no implica un mejor comportamiento frente a la corrosión.

EFFECTIVENESS OF INHIBITORS OF METAL CORROSION IN AQUEOUS ENVIRONMENTS WITH VARYING SALINITY

OpenAIRE

Носачова, Юлія Вікторівна; Макаренко, Ірина Миколаївна; Шаблій, Тетяна Олександрівна

2015-01-01

EFFECTIVENESS OF INHIBITORS OF METAL CORROSION IN AQUEOUS ENVIRONMENTS WITH VARYING SALINITYThe main reason for the growing problem of water quality in Ukraine is the increase of anthropogenic impacts on water resources caused by intense chemical, biological and radiation contamination of existing and potential sources for industrial and communal water supply. Especially polluted rivers in Donbass and Krivbas area, that turned into collectors of saline wastewater. Especially hard environment...

Stress corrosion cracking of Zircaloy-4 in non-aqueous iodine solutions

International Nuclear Information System (INIS)

Gomez Sanchez, Andrea V.

2006-01-01

In the present work the susceptibility to intergranular attack and stress corrosion cracking of Zircaloy-4 in different iodine alcoholic solutions was studied. The influence of different variables such as the molecular weight of the alcohols, the water content of the solutions, the alcohol type (primary, secondary or tertiary) and the temperature was evaluated. To determine the susceptibility to stress corrosion cracking the slow strain rate technique was used. Specimens of Zircaloy-4 were also exposed between 0.5 and 300 hours to the solutions without applied stress to evaluate the susceptibility to intergranular attack. The electrochemical behavior of the material in the corrosive media was studied by potentiodynamic polarization tests. It was determined that the active species responsible for the stress corrosion cracking of Zircaloy-4 in iodine alcoholic solutions is a molecular complex between the alcohol and iodine. The intergranular attack precedes the 'true' stress corrosion cracking phenomenon (which is associated to the transgranular propagation of the crack) and it is controlled by the diffusion of the active specie to the tip of the crack. Water acts as inhibitor to intergranular attack. Except for methanolic solutions, the minimum water content necessary to inhibit stress corrosion cracking was determined. This critical water content decreases when increasing the molecular weight of the alcohol. An explanation for this behavior is proposed. The susceptibility to stress corrosion cracking also depends on the type of the alcohol used as solvent. The temperature dependence of the crack propagation rate is in agreement with a thermal activated process, and the activation energy is consistent with a process controlled by the volume diffusion of the active species. (author) [es

Influence of alkali, silicate, and sulfate content of carbonated concrete pore solution on mild steel corrosion behavior

International Nuclear Information System (INIS)

L'Hostis, V.; Huet, B.; Tricheux, L.; Idrissi, H.

2010-01-01

The increase in the rebar corrosion rate due to the concrete carbonation is the major cause of reinforced concrete degradation. The aim of this study was to investigate the corrosion behavior of mild steel rebars in simulated carbonated concrete solution. For this purpose, thermodynamic calculations, electrochemical techniques, gravimetric measurements, and surface analyses were used. Thermodynamic investigations of the nature of the interstitial solution provides an estimation of the influence of sulfate (SO 4 2- ) and alkali (Na + , K + ) content on carbonate alkalinity of the CO 2 /H 2 O open system (pCO 2 =0. 3 mbar). in this system, calcium-silicate hydrates (C-S-H) remain thermodynamically unstable and amorphous silica controls silicate aqueous content at 100 ppm. Electrochemical results highlight a decrease in the corrosion rate with increasing carbonate alkalinity and the introduction of silicate. The introduction of sulfate at fixed carbonate alkalinity shows a dual effect: at high carbonate alkalinity, the corrosion rate is increased whereas at low carbonate alkalinity, corrosion rate is decreased. Those results are supported by surface analysis. Authors conclude that silicate and sulfate release from cement hydrates and fixation of alkali on carbonated hydrates are key parameters to estimate mild steel corrosion in carbonated concrete. (authors)

Corrosion behaviors of ceramics against liquid sodium. Sodium corrosion characteristics of sintering additives

International Nuclear Information System (INIS)

Tachi, Yoshiaki; Kano, Shigeki; Hirakawa, Yasushi; Yoshida, Eiichi

1998-01-01

It has been progressed as the Frontier Materials Research to research and develop ceramics to apply for several components of fast breeder reactor using liquid sodium as coolant instead of metallic materials. Grain boundary of ceramics has peculiar properties compared with matrix because most of ceramics are produced by hardening and firing their raw powders. Some previous researchers indicated that ceramics were mainly corroded at grain boundaries by liquid sodium, and ceramics could not be used under corrosive environment. Thus, it is the most important for the usage of ceramics in liquid sodium to improve corrosion resistance of grain boundaries. In order to develop the advanced ceramics having good sodium corrosion resistance among fine ceramics, which have recently been progressed in quality and characteristics remarkably, sodium corrosion behaviors of typical sintering additives such as MgO, Y 2 O 3 and AlN etc. have been examined and evaluated. As a result, the followings have been clarified and some useful knowledge about developing advanced ceramics having good corrosion resistance against liquid sodium has been obtained. (1) Sodium corrosion behavior of MgO depended on Si content. Samples containing large amount of Si were corroded severely by liquid sodium, whereas others with low Si contents showed good corrosion resistance. (2) Both Y 2 O 3 and AlN, which contained little Si, showed good sodium corrosion resistance. (3) MgO, Y 2 O 3 and AlN are thought to be corroded by liquid sodium, if they contain some SiO 2 . Therefore, in order to improve sodium corrosion resistance, it is very important for these ceramics to prevent the contamination of matrix with SiO 2 through purity control of their raw powders. (author)

Behavior of copper corrosion products in water loops of heat-exchange units

International Nuclear Information System (INIS)

Zarembo, V.I.; Kritskii, V.G.; Slobodov, A.A.; Puchkov, L.V.

1989-01-01

This communication is dedicated to an examination of copper corrosion products (CP) in the conditions of real aqueous-chemical regime (ACR) parameters. The deposition of these CP in steam-generating zones (up to 85% of their total amount) stimulate local types of corrosion. The solubility in Cu CP (Cu 2 O, CuO, Cu(OH) 2 )-water (H 2 O)-gas (H 2 , O 2 )-conditioning additives (HCl, KOH) systems was determined by computer modeling according to the minimum Gibbs energy criterion on the basis of selected and matched thermodynamic constants for various chemical forms of copper under standard conditions. As a result of the authors' calculations they obtained the solubilities in water of CuO, Cu 2 O and Cu(OH) 2 when changing the dosage of active gases from 0 to 10 -2 mole/kg of water, of acid or equal to that of saturated vapor of pure water. Thus, they were able to monitor the behavior of copper CP in conditions modeling those of real ACR in operating heat exchange units, including in conditions deviating from the standard

Mechanical behavior of precipitation hardenable steels exposed to highly corrosive environment

Science.gov (United States)

Rosa, Ferdinand

1994-01-01

Unexpected occurrences of failures, due to stress corrosion cracking (SCC) of structural components, indicate a need for improved characterization of materials and more advanced analytical procedures for reliably predicting structures performance. Accordingly, the purpose of this study was to determine the stress corrosion susceptibility of 15 - 5 PH steel over a wide range of applied strain rates in a highly corrosive environment. The selected environment for this investigation was a 3.5 percent NaCl aqueous solution. The material selected for the study was 15 - 5 PH steel in the H 900 condition. The Slow Strain Rate technique was used to test the metallic specimens.

Superhydrophobic copper surfaces fabricated by fatty acid soaps in aqueous solution for excellent corrosion resistance

Energy Technology Data Exchange (ETDEWEB)

Xu, Wenlong; Hu, Yuanyuan; Bao, Wenda; Xie, Xiaoyu; Liu, Yiran; Song, Aixin, E-mail: songaixin@sdu.edu.cn; Hao, Jingcheng

2017-03-31

Highlights: • The superhydrophobic property can be realized in a much quicker process (7.5 min) in aqueous solution than in ethanol. • The fabrication process of superhydrophobic metal surfaces greatly increases the safety in industrial manufacture in commercial scale. • The superhydrophobic copper surfaces show excellent corrosion resistance. - Abstract: A simple and safe one-step immersion method was developed to obtain the stable superhydrophobic copper surfaces with excellent corrosion resistance ability using fatty acids in water-medium instead of ethanol. An organic alkali, N,N-dimethylcyclohexylamine (DMCHA), was chosen to solve the poor solubility of fatty acids in water and the high Krafft point of carboxylate salts with inorganic counterions. The superhydrophobic property can be realized in a much quicker process (7.5 min) in aqueous solution than in ethanol (more than 2 d), which is universally feasible for the fabrication of superhydrophobic metal surfaces in industry scale, thereby greatly increasing the safety in industrial manufacture.

Effect of organic acids traces on the carbon steel corrosion behavior

International Nuclear Information System (INIS)

Stefanescu, D.; Radulescu; Mogosan, S.

2009-01-01

There are many different ways in which organic matter may get in water-steam cycles. One important pathway is constituted by organic matter admitted into the system by chemical make-up water under standard operation conditions (without inverse osmosis). The high molecular weight organic matter, in particularly polysaccharides are broken in organic acids, in particular acetic and formic acid. This paper presents an overview of the investigations undertaken referring to the behavior SA106 gr. B mild steel in secondary circuit aqueous environment contaminated with formic and acetic acid traces. The samples were filmed in static autoclaves in operation conditions of secondary circuit, in contaminated environment and after that they were investigated using metallographic microscopy and SEM. In addition, an electrochemical technique videlicet impedance spectroscopy (EIS) was used to investigate the corrosion behavior of SA106 gr. B carbon steel in secondary circuit medium contaminated with formic and acetic acid traces. (authors)

Aqueous corrosion of borosilicate glasses: experiments, modeling and Monte-Carlo simulations

International Nuclear Information System (INIS)

Ledieu, A.

2004-10-01

This work is concerned with the corrosion of borosilicate glasses with variable oxide contents. The originality of this study is the complementary use of experiments and numerical simulations. This study is expected to contribute to a better understanding of the corrosion of nuclear waste confinement glasses. First, the corrosion of glasses containing only silicon, boron and sodium oxides has been studied. The kinetics of leaching show that the rate of leaching and the final degree of corrosion sharply depend on the boron content through a percolation mechanism. For some glass contents and some conditions of leaching, the layer which appears at the glass surface stops the release of soluble species (boron and sodium). This altered layer (also called the gel layer) has been characterized with nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. Second, additional elements have been included in the glass composition. It appears that calcium, zirconium or aluminum oxides strongly modify the final degree of corrosion so that the percolation properties of the boron sub-network is no more a sufficient explanation to account for the behavior of these glasses. Meanwhile, we have developed a theoretical model, based on the dissolution and the reprecipitation of the silicon. Kinetic Monte Carlo simulations have been used in order to test several concepts such as the boron percolation, the local reactivity of weakly soluble elements and the restructuring of the gel layer. This model has been fully validated by comparison with the results on the three oxide glasses. Then, it has been used as a comprehensive tool to investigate the paradoxical behavior of the aluminum and zirconium glasses: although these elements slow down the corrosion kinetics, they lead to a deeper final degree of corrosion. The main contribution of this work is that the final degree of corrosion of borosilicate glasses results from the competition of two opposite mechanisms

Investigation of corrosion behavior of Mg-steel laser-TIG hybrid lap joints

International Nuclear Information System (INIS)

Liu Liming; Xu Rongzheng

2012-01-01

Highlights: ► Galvanic corrosion increases the corrosion rate of the Mg-steel joint. ► Fe splashes lower the corrosion resistance of the joint greatly. ► The effect of grain refinement on the corrosion behavior of the joint is slight. ► Ni or Cu interlayer could not improve the corrosion resistance of fusion zone. ► The arc-sprayed coating could enhance the reliability of weld joint. - Abstract: The paper investigates the corrosion behavior of the lap joint of AZ31 magnesium alloy to Q235 steel with salt solution immersion testing and electrochemical testing. It is demonstrated that grain refinement resulting from the welding process has little effect on the corrosion behavior of the lap joint. However, the cathodic phases formed in the welding process and the galvanic corrosion between magnesium alloy and steel decrease the corrosion resistance of the joint greatly. Besides, neither Cu nor Ni, as filler material, could improve the corrosion resistance of the joint, but the arc-sprayed Al coating acting as a protective layer could.

Galvanic Corrosion between Alloy 690 and Magnetite in Alkaline Aqueous Solutions

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Soon-Hyeok Jeon

2015-12-01

Full Text Available The galvanic corrosion behavior of Alloy 690 coupled with magnetite has been investigated in an alkaline solution at 30 °C and 60 °C using a potentiodynamic polarization method and a zero resistance ammeter. The positive current values were recorded in the galvanic couple and the corrosion potential of Alloy 690 was relatively lower. These results indicate that Alloy 690 behaves as the anode of the pair. The galvanic coupling between Alloy 690 and magnetite increased the corrosion rate of Alloy 690. The temperature increase led to an increase in the extent of galvanic effect and a decrease in the stability of passive film. Galvanic effect between Alloy 690 and magnetite is proposed as an additional factor accelerating the corrosion rate of Alloy 690 steam generator tubing in secondary water.

Electrochemical investigation on the effects of sulfate ion concentration, temperature and medium pH on the corrosion behavior of Mg–Al–Zn–Mn alloy in aqueous ethylene glycol

Directory of Open Access Journals (Sweden)

H. Medhashree

2017-03-01

Full Text Available The effects of sulfate ion concentration, temperature and medium pH on the corrosion of Mg–Al–Zn–Mn alloy in 30% aqueous ethylene glycol solution have been investigated by electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy methods. Surface morphology of the alloy was examined before and after immersing in the corrosive media by scanning electron microscopy (SEM and energy dispersion X-ray (EDX analysis. Activation energy, enthalpy of activation and entropy of activation were calculated from Arrhenius equation and transition state theory equation. The obtained results indicate that, the rate of corrosion increases with the increase in sulfate ion concentration and temperature of the medium and decreases with the increase in the pH of the medium.

Measurements and mechanisms of localized aqueous corrosion in aluminum-lithium alloys

Science.gov (United States)

Buchheit, Rudolph G., Jr.; Stoner, Glenn E.

1990-01-01

Like most heat treatable aluminum alloys, localized corrosion and stress corrosion of Al-Li-Cu alloys is strongly dependent on the nature and distribution of second phase particles. To develop a mechanistic understanding of the role of localized corrosion in the stress corrosion process, bulk samples of T(sub 1) (Al2CuLi) and a range of Al-Cu-Fe impurity phases were prepared for electrochemical experiments. Potentiodynamic polarization and galvanic couple experiments were performed in standard 0.6 M NaCl and in simulated crevice solutions to assess corrosion behavior of these particles with respect to the alpha-Al matrix. A comparison of time to failure versus applied potential using a constant load, smooth bar SCC test technique in Cl(-), Cl(-)/CrO4(2-), and Cl(-)/CO3(2-) environments shows that rapid failures are to be expected when applied potentials are more positive than the breakaway potential (E sub br) of T(sub 1) (crack tip) but less than E(sub br) of alpha-Al (crack walls). It is shown that this criterion is not satisfied in aerated Cl(-) solutions. Accordingly, SCC resistance is good. This criterion is satisfied, however, in an alkaline isolated fissure exposed to a CO2 containing atmosphere. Rapid failure induced by these fissures was recently termed preexposure embrittlement. Anodic polarization shows that the corrosion behavior of T(sub 1) is relatively unaffected in alkaline CO3(2-) environments but the alpha-Al phase is rapidly passivated. X ray diffraction of crevice walls from artificial crevices suggests that passivation of alpha-Al occurs as hydrotalcite-type compound (LiAl2(OH)6)2(+) - CO3(2-) - nH2O.

The Effect of Homogenization on the Corrosion Behavior of Al-Mg Alloy

Science.gov (United States)

Li, Yin; Hung, Yuanchun; Du, Zhiyong; Xiao, Zhengbing; Jia, Guangze

2018-04-01

The effect of homogenization on the corrosion behavior of 5083-O aluminum alloy is presented in this paper. The intergranular corrosion and exfoliation corrosion were used to characterize the discussed corrosion behavior of 5083-O aluminum alloy. The variations in the morphology, the kind and distribution of the precipitates, and the dislocation configurations in the samples after the homogenization were evaluated using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The effects of the highly active grain boundary character distribution and the types of constituent particles on the corrosion are discussed on the basis of experimental observations. The results indicated that the corrosion behavior of 5083-O alloy was closely related to the microstructure obtained by the heat treatment. Homogenization carried out after casting had the optimal effect on the overall corrosion resistance of the material. Nevertheless, all samples could satisfy the requirements of corrosion resistance in marine applications.

Corrosion behavior of Zr-x(Nb, Sn and Cu) binary alloys

International Nuclear Information System (INIS)

Kim, M. H.; Lee, M. H.; Park, S. Y.; Jung, Y. H.; We, M. Y.

1999-01-01

For the development of advanced zirconium alloys for nuclear fuel cladding, the corrosion behaviors of zirconium binary alloys were studied on the Zr-xNb, Zr-xSn, and Zr-xCu alloys. The corrosion test were performed in water at 360 deg C, steam at 400 deg C and LiOH at 360 deg C for 45 days. The corrosion behaviors of Zr-xNb was similar to that of Zr-xCu alloys. However, the corrosion behavior of Zr-xSn was different from Zr-xNb and Zr-xCu. The weight gain of Zr-xNb and Zr-xCu was increased with addition of alloying elements. When Sn is added to Zr matrix in range below the solubility limit, the corrosion resistance decrease with increasing Sn-content, while in the range over solubility limit, Sn has an adverse effect on the corrosion resistance. Especially, Zr-xSn alloys showed higher corrosion resistance than Zr-xNb and Zr-xCu alloys in LiOH solution

Flexural behavior of bonded post-tensioned concrete beams under strand corrosion

International Nuclear Information System (INIS)

Zhang, Xuhui; Wang, Lei; Zhang, Jianren; Ma, Yafei; Liu, Yongming

2017-01-01

Highlights: • Flexural behavior of bonded PT beams with strand corrosion is experimental tested. • Cracking, stiffness, ultimate strength, failure & ductility of beams are clarified. • A coefficient is proposed to measure incompatible strain between strand & concrete. - Abstract: An experimental test is performed to investigate the flexural behavior of bonded post-tensioned concrete beams under strand corrosion. Eight beams are designed and subjected to accelerated method to different corrosion levels. The initial stiffness of beams is observed by cyclic loading-unloading test during the corrosion procedure. Corrosion effects on concrete cracking, post-cracking stiffness, ultimate strength, failure mode and ductility are then clarified by the flexural test. And, a coefficient is introduced to quantify the incompatible strain between corroded strand and concrete. Results show that the prestress force loss of strand has almost the linear relation with corrosion loss. Strand corrosion affects slightly the initial stiffness of beam before flexural cracking, but degrades significantly the post-cracking stiffness of beam as the corrosion loss exceeds 27.0%. Slight corrosion of strand has little effects on beams flexural behavior. The severe corrosion, however, decreases the number of crack, changes the failure mode form the concrete crushing to strand rupture, degrades the ductility and the ultimate strength of beams, and leads to the incompatible strain between strand and concrete. In the present test, the incompatible strain decreases about 20% of the flexural strength as the corrosion loss exceeds 27.0%.

Flexural behavior of bonded post-tensioned concrete beams under strand corrosion

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xuhui [College of Civil Engineering and Mechanics, Xiangtan University, 411105 Xiangtan (China); School of Civil Engineering and Architecture, Changsha University of Science & Technology, 410114 Changsha (China); Industry Key Laboratory of Traffic Infrastructure Security Risk Management (CSUST), 410114 Changsha (China); Wang, Lei, E-mail: leiwlei@hotmail.com [School of Civil Engineering and Architecture, Changsha University of Science & Technology, 410114 Changsha (China); Industry Key Laboratory of Traffic Infrastructure Security Risk Management (CSUST), 410114 Changsha (China); Zhang, Jianren; Ma, Yafei [School of Civil Engineering and Architecture, Changsha University of Science & Technology, 410114 Changsha (China); Industry Key Laboratory of Traffic Infrastructure Security Risk Management (CSUST), 410114 Changsha (China); Liu, Yongming [School for Engineering of Matter, Transport and Energy, Arizona State University, 85281 Tempe, AZ (United States)

2017-03-15

Highlights: • Flexural behavior of bonded PT beams with strand corrosion is experimental tested. • Cracking, stiffness, ultimate strength, failure & ductility of beams are clarified. • A coefficient is proposed to measure incompatible strain between strand & concrete. - Abstract: An experimental test is performed to investigate the flexural behavior of bonded post-tensioned concrete beams under strand corrosion. Eight beams are designed and subjected to accelerated method to different corrosion levels. The initial stiffness of beams is observed by cyclic loading-unloading test during the corrosion procedure. Corrosion effects on concrete cracking, post-cracking stiffness, ultimate strength, failure mode and ductility are then clarified by the flexural test. And, a coefficient is introduced to quantify the incompatible strain between corroded strand and concrete. Results show that the prestress force loss of strand has almost the linear relation with corrosion loss. Strand corrosion affects slightly the initial stiffness of beam before flexural cracking, but degrades significantly the post-cracking stiffness of beam as the corrosion loss exceeds 27.0%. Slight corrosion of strand has little effects on beams flexural behavior. The severe corrosion, however, decreases the number of crack, changes the failure mode form the concrete crushing to strand rupture, degrades the ductility and the ultimate strength of beams, and leads to the incompatible strain between strand and concrete. In the present test, the incompatible strain decreases about 20% of the flexural strength as the corrosion loss exceeds 27.0%.

Suppression of aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} by reducing dissolved oxygen concentration for high-performance magnetic refrigeration

Energy Technology Data Exchange (ETDEWEB)

Fujieda, S., E-mail: fujieda@tagen.tohoku.ac.jp; Fukamichi, K.; Suzuki, S.

2014-07-05

Highlights: • The aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} and its suppression were investigated. • The lattice expansion after immersion was caused by the hydrogen absorption. • The itinerant-electron metamagnetic transition became indistinct after immersion. • The aqueous corrosion was suppressed by reducing the dissolved oxygen concentration. - Abstract: The itinerant-electron metamagnetic transition of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} becomes indistinct after immersion in distilled-water containing about 8 ppm of the dissolved oxygen (DO) concentration because of aqueous corrosion. However, the aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} is significantly suppressed by reducing the DO concentration. Thus, isothermal magnetic entropy change after immersion for 30 days in deaerated distilled-water with a DO concentration less than 0.1 ppm is larger than that after immersion for 5 days in distilled-water containing about 8 ppm of the DO concentration. Consequently, the reduction of the DO concentration is effective for preservation of the excellent magnetocaloric effects of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} in an aqueous solution, which is a promising heat transfer fluid of room-temperature magnetic refrigeration.

Corrosion behavior of sensitized duplex stainless steel.

Science.gov (United States)

Torres, F J; Panyayong, W; Rogers, W; Velasquez-Plata, D; Oshida, Y; Moore, B K

1998-01-01

The present work investigates the corrosion behavior of 2205 duplex stainless steel in 0.9% NaCl solution after various heat-treatments, and compares it to that of 316L austenitic stainless steel. Both stainless steels were heat-treated at 500, 650, and 800 degrees C in air for 1 h, followed by furnace cooling. Each heat-treated sample was examined for their microstructures and Vickers micro-hardness, and subjected to the X-ray diffraction for the phase identification. Using potentiostatic polarization method, each heat-treated sample was corrosion-tested in 37 degrees C 0.9% NaCl solution to estimate its corrosion rate. It was found that simulated sensitization showed an adverse influence on both steels, indicating that corrosion rates increased by increasing the sensitization temperatures.

Investigation of corrosion behavior of Mg-steel laser-TIG hybrid lap joints

Energy Technology Data Exchange (ETDEWEB)

Liu Liming, E-mail: liulm@dlut.edu.cn [Key Laboratory of Liaoning Advanced Welding and Joining Technology, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Xu Rongzheng [Key Laboratory of Liaoning Advanced Welding and Joining Technology, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

2012-01-15

Highlights: Black-Right-Pointing-Pointer Galvanic corrosion increases the corrosion rate of the Mg-steel joint. Black-Right-Pointing-Pointer Fe splashes lower the corrosion resistance of the joint greatly. Black-Right-Pointing-Pointer The effect of grain refinement on the corrosion behavior of the joint is slight. Black-Right-Pointing-Pointer Ni or Cu interlayer could not improve the corrosion resistance of fusion zone. Black-Right-Pointing-Pointer The arc-sprayed coating could enhance the reliability of weld joint. - Abstract: The paper investigates the corrosion behavior of the lap joint of AZ31 magnesium alloy to Q235 steel with salt solution immersion testing and electrochemical testing. It is demonstrated that grain refinement resulting from the welding process has little effect on the corrosion behavior of the lap joint. However, the cathodic phases formed in the welding process and the galvanic corrosion between magnesium alloy and steel decrease the corrosion resistance of the joint greatly. Besides, neither Cu nor Ni, as filler material, could improve the corrosion resistance of the joint, but the arc-sprayed Al coating acting as a protective layer could.

Structure and Corrosion Resistance of Welded Joints of Alloy 1151 in Marine Atmosphere

Science.gov (United States)

Bakulo, A. V.; Yakushin, B. F.; Puchkov, Yu. A.

2017-07-01

The corrosion behavior of joints formed by TIG and IMIG welding from clad sheets of heat-hardenable aluminum alloy 1151 of the Al - Cu - Mg system is studied. The corrosion tests are performed in an aqueous solution of NaCl in a salt-spray chamber. The welded joints are subjected to a metallographic analysis.

Magnesium-Based Corrosion Nano-Cells For Reductive Transformation Of Contaminants

Science.gov (United States)

Magnesium, with its potential to reduce a variety of aqueous contaminants, unique self-limiting corrosion behavior affording long active life times, natural abundance, low cost, and environmentally friendly nature, promises to be an effective technology. However, nanoparticles o...

The influence of Zr substitution for Nb on the corrosion behaviors of the Ni-Nb-Zr bulk metallic glasses

Science.gov (United States)

Li, DengKe; Zhu, ZhengWang; Zhang, HaiFeng; Wang, AiMin; Hu, ZhuangQi

2012-12-01

The influence of Zr content on corrosion behaviors of the Ni61.5Nb38.5- x Zr x ( x=1, 3, 5, 7, 9 at.%) bulk metallic glasses (BMGs) in 1 M HCl aqueous solution was investigated by potentiodynamic polarization measurements and X-ray photo-electron spectroscopy (XPS). It was found that these BMG alloys possess superior corrosion resistance, that is, with large passive region of about 1.5 V and low passive current density (as low as 0.05 Am-2 for Ni61.5Nb31.5Zr7). XPS analysis indicates that the high corrosion resistance is attributed to the formation of Nb- and Zr-enriched surface films formed in the aggressive acid solution. The Zr substitution for Nb effectively reduces the Ni content, particularly the metallic state Ni content in the surface films, which depresses the electrical conduction of the surface films and reduces the passive current density, thus leading to the enhancement of the corrosion resistance of these Ni-Nb-Zr BMGs. These alloys may potentially be useful for engineering applications.

Anomalous dissolution of metals and chemical corrosion

Directory of Open Access Journals (Sweden)

DRAGUTIN M. DRAZIC

2005-03-01

Full Text Available An overview is given of the anomalous behavior of some metals, in particular Fe and Cr, in acidic aqueous solutions during anodic dissolution. The anomaly is recognizable by the fact that during anodic dissolutionmore material dissolves than would be expected from the Faraday law with the use of the expected valence of the formed ions. Mechanical disintegration, gas bubble blocking, hydrogen embrittlement, passive layer cracking and other possible reasons for such behavior have been discussed. It was shown, as suggested by Kolotyrkin and coworkers, that the reason can be, also, the chemical reaction in which H2O molecules with the metal form metal ions and gaseous H2 in a potential independent process. It occurs simultaneously with the electrochemical corrosion process, but the electrochemical process controls the corrosion potential. On the example of Cr in acid solution itwas shown that the reason for the anomalous behavior is dominantly chemical dissolution, which is considerably faster than the electrochemical corrosion, and that the increasing temperature favors chemical reaction, while the other possible reasons for the anomalous behavior are of negligible effect. This effect is much smaller in the case of Fe, but exists. The possible role of the chemical dissolution reacton and hydrogen evolution during pitting of steels and Al and stress corrosion cracking or corrosion fatigue are discussed.

Corrosion studies of austenitic and duplex stainless steels in aqueous lithium bromide solution at different temperatures

International Nuclear Information System (INIS)

Igual Munoz, A.; Garcia Anton, J.; Lopez Nuevalos, S.; Guinon, J.L.; Perez Herranz, V.

2004-01-01

The corrosion behavior of three stainless steels EN 14311, EN 14429 (austenitic stainless steels) and EN 14462 (duplex stainless steel) was studied in a commercial LiBr solution (850 g/l LiBr solution containing chromate as inhibitor) at different temperatures (25, 50, 75 and 85 deg C) by electrochemical methods. Open circuit potentials shifted towards more active values as temperature increased, while corrosion potentials presented the opposite tendency. The most resistant alloys to general corrosion were EN 14429 and EN 14462 because they had the lowest corrosion current for all temperatures. In all the cases corrosion current increases with temperature. Pitting corrosion resistance is improved by the EN 14462, which presented the highest pitting potential, and the lowest passivation current for the whole range of temperatures studied. The duplex alloy also presents the worst repassivation behavior (in terms of the narrowest difference between corrosion potential and pitting potential); it does not repassivate from 50 deg C

Some problems on the aqueous corrosion of structural materials in nuclear engineering; Problemes de corrosion aqueuse de materiaux de structure dans les constructions nucleaires

Energy Technology Data Exchange (ETDEWEB)

Coriou, H; Grall, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

The purpose of this report is to give a comprehensive view of some aqueous corrosion studies which have been carried out with various materials for utilization either in nuclear reactors or in irradiated fuel treatment plants. The various subjects are listed below. Austenitic Fe-Ni-Cr alloys: the behaviour of austenitic Fe-Ni-Cr alloys in nitric medium and in the presence of hexavalent chromium; the stress corrosion of austenitic alloys in alkaline media at high temperatures; the stress corrosion of austenitic Fe-Ni-Cr alloys in 650 C steam. Ferritic steels: corrosion of low alloy steels in water at 25 and 360 C; zirconium alloys; the behaviour of ultrapure zirconium in water and steam at high temperature. (authors) [French] On presente un ensemble d'etudes de corrosion en milieu aqueux effectuees sur des materiaux utilises, soit dans la construction des reacteurs soit pour la realisation des usines de traitement des combustibles irradies. Les differents sujets etudies sont les suivants. Les alliages austenitiques Fer-Nickel-Chrome: comportement d'alliages austenitiques fer-nickel-chrome en milieu nitrique en presence de chrome hexavalent; Corrosion sous contrainte d'alliages austenitiques dans les milieux alcalins a haute temperature; Corrosion sous contrainte dans la vapeur a 650 C d'alliages austenitiques fer-nickel-chrome. Les aciers ferritiques; Corrosion d'aciers faiblement allies dans l'eau a 25 et 360 C; le zirconium et ses alliages; Comportement du zirconium tres pur dans l'eau et la vapeur a haute temperature. (auteurs)

Corrosion Behavior of Nickel-Plated Alloy 600 in High Temperature Water

International Nuclear Information System (INIS)

Kim, Ji Hyun; Hwang, Il Soon

2008-01-01

In this paper, electrochemical and microstructural characteristics of nickel-plated Alloy 600 wee investigated in order to identify the performance of electroless Ni-plating on Alloy 600 in high-temperature aqueous condition with the comparison of electrolytic nickel-plating. For high temperature corrosion test of nickel-plated Alloy 600, specimens were exposed for 770 hours to typical PWR primary water condition. During the test, open circuit potentials (OCP's) of all specimens were measured using a reference electrode. Also, resistance to flow accelerated corrosion (FAC) test was examined in order to check the durability of plated layers in high-velocity flow environment at high temperature. After exposures to high flow rate aqueous condition, the integrity of surfaces was confirmed by using both scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). For the field application, a remote process for electroless nickel-plating was demonstrated using a plate specimen with narrow gap on a laboratory scale. Finally, a practical seal design was suggested for more convenient application

Corrosion behavior of 321 stainless steel in low-acidity uranium nitrate solution

International Nuclear Information System (INIS)

Liao Junsheng; Sun Ying; Zhang Wanglin; Ding Ping; Yang Jiangrong; Wu Lunqiang

2003-01-01

Weighing and electrochemical methods have been used to investigate the high-temperature uniform corrosion and electrochemical corrosion behavior of lCr18Ni9Ti (321) stainless steel in uranium nitrate solution at different concentrations and pH values. The uniform corrosion results showed that the corrosion rate of 321 stainless steel was less than 0.04 g/m 2 .h, and the visible change of surface smoothness was not observed through 960 h. It was perfect corrosion-resisting in obtained conditions. The electro-chemical corrosion behavior study has been performed to investigate 321 stainless steel in uranium nitrate solutions of the dissolved and saturated oxygen. The corrosion potential and corrosion current density were obtained. Auger photoelectron spectroscopy for measurement of uranium in specimen was used to indicate that uranium is in corrosion product. The corrosion film was measured by Ar ion gun sputter, and the thickness is 10-15 nm. (authors)

Corrosion Study of Mild Steel in Aqueous Sulfuric Acid Solution Using 4-Methyl-4H-1,2,4-Triazole-3-Thiol and 2-Mercaptonicotinic Acid—An Experimental and Theoretical Study

Directory of Open Access Journals (Sweden)

Valbonë V. Mehmeti

2017-08-01

Full Text Available The corrosion behavior of mild steel in 0.1 M aqueous sulfuric acid medium has been studied using weight loss, potentiodynamic polarization measurements, quantum chemical calculations, and molecular dynamic simulations in the presence and absence of 4-methyl-4H-1,2,4-triazole-3-thiol and 2-mercaptonicotinic acid. Potentiodynamic measurements indicate that these compounds mostly act as mixed inhibitors due to their adsorption on the mild steel surface. The goal of the study was to use theoretical calculations to better understand the inhibition. Monte Carlo simulation was used to calculate the adsorption behavior of the studied molecules onto Fe (1 1 1 and Fe2O3 (1 1 1 surface. The molecules were also studied with the density functional theory (DFT, using the B3LYP functional in order to determine the relationship between the molecular structure and the corrosion inhibition behavior. More accurate adsorption energies between the studied molecules and iron or iron oxide were calculated by using DFT with periodic boundary conditions. The calculated theoretical parameters gave important assistance into the understanding the corrosion inhibition mechanism expressed by the molecules and are in full agreement with the experimental results.

Corrosion and Corrosion-Fatigue Behavior of 7075 Aluminum Alloys Studied by In Situ X-Ray Tomography

Science.gov (United States)

Stannard, Tyler

7XXX Aluminum alloys have high strength to weight ratio and low cost. They are used in many critical structural applications including automotive and aerospace components. These applications frequently subject the alloys to static and cyclic loading in service. Additionally, the alloys are often subjected to aggressive corrosive environments such as saltwater spray. These chemical and mechanical exposures have been known to cause premature failure in critical applications. Hence, the microstructural behavior of the alloys under combined chemical attack and mechanical loading must be characterized further. Most studies to date have analyzed the microstructure of the 7XXX alloys using two dimensional (2D) techniques. While 2D studies yield valuable insights about the properties of the alloys, they do not provide sufficiently accurate results because the microstructure is three dimensional and hence its response to external stimuli is also three dimensional (3D). Relevant features of the alloys include the grains, subgrains, intermetallic inclusion particles, and intermetallic precipitate particles. The effects of microstructural features on corrosion pitting and corrosion fatigue of aluminum alloys has primarily been studied using 2D techniques such as scanning electron microscopy (SEM) surface analysis along with post-mortem SEM fracture surface analysis to estimate the corrosion pit size and fatigue crack initiation site. These studies often limited the corrosion-fatigue testing to samples in air or specialized solutions, because samples tested in NaCl solution typically have fracture surfaces covered in corrosion product. Recent technological advancements allow observation of the microstructure, corrosion and crack behavior of aluminum alloys in solution in three dimensions over time (4D). In situ synchrotron X-Ray microtomography was used to analyze the corrosion and cracking behavior of the alloy in four dimensions to elucidate crack initiation at corrosion pits

Corrosion of low alloy steel containing 0.5% chromium in supercritical CO2-saturated brine and water-saturated supercritical CO2 environments

Science.gov (United States)

Wei, Liang; Gao, Kewei; Li, Qian

2018-05-01

The corrosion behavior of P110 low-Cr alloy steel in supercritical CO2-saturated brine (aqueous phase) and water-saturated supercritical CO2 (SC CO2 phase) was investigated. The results show that P110 steel primarily suffered general corrosion in the aqueous phase, while severe localized corrosion occurred in the SC CO2 phase. The formation of corrosion product scale on P110 steel in the aqueous phase divided into three stages: formation of the initial corrosion layer containing amorphous Cr(OH)3, FeCO3 and a small amount of Fe3C; transformation of initial corrosion layer to mixed layer, which consisted of FeCO3 and a small amount of Cr(OH)3 and Fe3C; growth and dissolution of the mixed layer. Finally, only a single mixed layer covered on the steel in the aqueous phase. However, the scale formed in SC CO2 phase consisted of two layers: the inner mixed layer and the dense outer FeCO3 crystalline layer.

Online monitoring of corrosion behavior in molten metal using laser-induced breakdown spectroscopy

Science.gov (United States)

Zeng, Qiang; Pan, Congyuan; Li, Chaoyang; Fei, Teng; Ding, Xiaokang; Du, Xuewei; Wang, Qiuping

2018-04-01

The corrosion behavior of structure materials in direct contact with molten metals is widespread in metallurgical industry. The corrosion of casting equipment by molten metals is detrimental to the production process, and the corroded materials can also contaminate the metals being produced. Conventional methods for studying the corrosion behavior by molten metal are offline. This work explored the application of laser-induced breakdown spectroscopy (LIBS) for online monitoring of the corrosion behavior of molten metal. The compositional changes of molten aluminum in crucibles made of 304 stainless steel were obtained online at 1000 °C. Several offline techniques were combined to determine the corrosion mechanism, which was highly consistent with previous studies. Results proved that LIBS was an efficient method to study the corrosion mechanism of solid materials in molten metal.

Corrosion Behavior of Heat Affected Zone of AISI 321 stainless steel

International Nuclear Information System (INIS)

Ahn, Yong Sik; Park, Hwa Soon; Kim, Yeong Hwan; Won, Tae Yeon; Lee, Sang Lae

1994-01-01

Intergranular corrosion behavior of heat affected zone(HAZ) has been investigated for Ti-stabilized austenitic stainless steel AISI 321. It was observed that grain boundaries at HAZ of the steel with Ti/C ratio of 6.2 were corroded significantly after sensitization heat treatment. The increase of the Ti/C ratio up to 9.6 results in the evident decrease of intergranular corrosion. Weld simulation and intergranular corrosion test in 65% HNO 3 was performed. Influence of various thermal cycles on the intergranular corrosion was investigated. These results are discussed in terms of the behavior of TiC and Cr 23 C 6 precipitates

Analysis of corrosion behavior of KOFA cladding

International Nuclear Information System (INIS)

Lee, Chan Bock; Kim, Ki Hang; Seo, Keum Seok; Chung, Jin Gon

1994-01-01

The corrosion behavior of KOFA cladding was analyzed using the oxide measurement data of KOFA fuel irradiated up to the fuel rod burnup of 35,000 MWD/MTU for two cycles in Kori-2. Even though KOFA cladding is a standard Zircaloy-4 manufactured by Westinghouse according to the Siemens/KWU's HCW (Highly Cold Worked) standard Zircaloy-4 specification, it was expected that in-pile corrosion behavior of KOFA cladding would not be equivalent to that of Siemens/KWU's cladding due to the differences in such manufacturing processes as cold work and heat treatment. The analysis of measured KOFA cladding oxidation showed that oxidation of KOFA cladding is at least 19 % lower than the design analysis based upon Siemens/KWU's HCW standard Zircaloy-4 cladding. Lower corrosion of KOFA cladding seems to result from the differences in the manufacturing processes and chemical composition although the burnup and oxide layer thickness of the measured fuel rods is relatively low and the amount of the oxidation data base is small

Corrosion behavior of the aluminum under the simulated environmental condition of low-level waste. Part 1. Effect of dry storage on the corrosion behavior of pre-filmed specimen

International Nuclear Information System (INIS)

Fujiwara, Kazutoshi; Tani, Junichi; Tanaka, Yukihisa

2016-01-01

Aluminum alloy remains in the Low-level Radioactive Waste (LLW) generated at nuclear facilities. It is well known that aluminum reactors to the alkaline component of cement, or water, generating hydrogen gas. For the saft management of radioactive waste disposal facilities, it is necessary to evaluate the corrosion behavior of aluminum and the hydrogen generation behavior in consideration with transition of the burial environment. In the present study, the corrosion behaviors of aluminum in the alkaline solutions at 15degC were evaluated. Pure aluminium was used as specimen. The test solutions used in this study were water in equilibrium with the cement paste grain produced from ordinary portland cement (OPC). The temperature and pH of solutions were 15degC and 11.5-12.5, respectively. In order to make a corrosion product on the surface, the specimens were immersed in the solution for about 3000 hours as pretreatment. The corrosion behaviors of pre-filmed specimen were evaluated after drying. The test results shows that the maximum in a corrosion rate appeared in early stages and it decrease to less than 1x10 -3 mm/y. The maximum did not appear when the corrosion products were formed in the OPC grain as conditions similar to actual environment. (author)

The corrosion behavior of iron and aluminum under waste disposal conditions

International Nuclear Information System (INIS)

Fujisawa, R.; Cho, T.; Sugahara, K.; Takizawa, Y.; Hironaga, M.

1997-01-01

The generation of hydrogen gas from metallic waste in corrosive disposal environment is an important issue for the safety analysis of low-level radioactive waste disposal facilities in Japan. In particular iron and aluminum are the possibly important elements regarding the gas generation. However, the corrosion behavior of these metals has not been sufficiently investigated under the highly alkaline non-oxidizing disposal conditions yet. The authors studied the corrosion behavior of iron and aluminum under simulated disposal environments. The quantity of hydrogen gas generated from iron was measured in a closed cell under highly alkaline non-oxidizing conditions. The observed corrosion rate of iron in the initial period of immersion was 4 nm/year at 15 C, 20 nm/year at 30 C, and 200 nm/year at 45 C. The activation energy was found to be 100 kJ/mol from Arrhenius plotting of the above corrosion rates. The corrosion behavior of aluminum was studied under an environment simulating conditions in which aluminum was solidified with mortar. In the initial period aluminum corroded rapidly with a corrosion rate of 20 mm/year. However, the corrosion rate decreased with time, and after 1,000 hours the rate reached 0.001 to 0.01 mm/year. Thus the authors obtained data on hydrogen gas generation from iron and aluminum under the disposal environment relevant to the safety analysis of low-level radioactive disposal facilities in Japan

Corrosion of the CANDU steam generator tubesheet due to aqueous environment pH

International Nuclear Information System (INIS)

Lucan, D.; Fulger, M.; Velciu, L.

2009-01-01

There is a side environment that is known to be affected significantly by several factors dependent on the balance of plant conditions (condenser leaks, condensate polishing, and coolant system materials) as well on the operational conditions, particularly through their thermal-hydraulic effects. The presence of tube-tubesheet crevices and restricted flow areas within sludge or surface deposits provides for local concentration sites for various impurities, including the acidic ones. The generalized corrosion can occur and can affect the steam generator performances. It is very important to understand the generalized corrosion mechanism with the purpose of evaluating the amount of corrosion products which exist in the steam generator after a determined period of operation. The purpose of this work consists in the assessment of corrosion behavior of the tubesheet material (carbon steel SA508 cl.2) at normal secondary circuit parameters (temperature, 260 deg. C, pressure, 5.1 MPa). The testing environment was the demineralized water without impurities, at different pH values regulated with morpholine and cyclohexylamine (all volatile treatment - AVT). The results are presented like micrographs, potentiodynamic curves and graphics representing loss of metal by corrosion, corrosion rate, the total corrosion products, the adherent corrosion products, the released corrosion products and the release of the metal. (authors)

The corrosion behavior of hafnium in high-temperature-water environments

Energy Technology Data Exchange (ETDEWEB)

Rishel, D.M.; Smee, J.D.; Kammenzind, B.F.

1999-10-01

The high-temperature-water corrosion performance of hafnium is evaluated. Corrosion kinetic data are used to develop correlations that are a function of time and temperature. The evaluation is based on corrosion tests conducted in out-of-pile autoclaves and in out-of-flux locations of the Advanced Test Reactor (ATR) at temperatures ranging from 288 to 360 C. Similar to the corrosion behavior of unalloyed zirconium, the high-temperature-water corrosion response of hafnium exhibits three corrosion regimes: pretransition, posttransition, and spalling. In the pretransition regime, cubic corrosion kinetics are exhibited, whereas in the posttransition regime, linear corrosion kinetics are exhibited. Because of the scatter in the spalling regime data, it is not reasonable to use a best fit of the data to describe spalling regime corrosion. Data also show that neutron irradiation does not alter the corrosion performance of hafnium. Finally, the data illustrate that the corrosion rate of hafnium is significantly less than that of Zircaloy-2 and Zircaloy-4.

Effect of Molybdenum on the Corrosion Behavior of High-Entropy Alloys CoCrFeNi2 and CoCrFeNi2Mo0.25 under Sodium Chloride Aqueous Conditions

Directory of Open Access Journals (Sweden)

Alvaro A. Rodriguez

2018-01-01

Full Text Available The corrosion behavior of high-entropy alloys (HEAs CoCrFeNi2 and CoCrFeNi2Mo0.25 was investigated in 3.5 wt. percent sodium chloride (NaCl at 25°C by electrochemical methods. Their corrosion parameters were compared to those of HASTELLOY® C-276 (UNS N10276 and stainless steel 316L (UNS 31600 to assess the suitability of HEAs for potential industrial applications in NaCl simulating seawater type environments. The corrosion rates were calculated using corrosion current determined from electrochemical experiments for each of the alloys. In addition, potentiodynamic polarization measurements can indicate active, passive, and transpassive behavior of the metal as well as potential susceptibility to pitting corrosion. Cyclic voltammetry (CV can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy (EIS elucidates the corrosion mechanism under studied conditions. The results of the electrochemical experiments and scanning electron microscopy (SEM analyses of the corroded surfaces revealed general corrosion on alloy CoCrFeNi2Mo0.25 and HASTELLOY C-276 and pitting corrosion on alloy CoCrFeNi2 and stainless steel 316L.

The role of nuclear analytical techniques in the study of aqueous corrosion of glasses

International Nuclear Information System (INIS)

Trocellier, P.

1984-01-01

Direct observation of resonant nuclear reactions, backscattering spectrometry and X ray microanalysis with a nuclear microprobe were used to determine elementary depth profiles in the near surface region of leached glasses. Some computing programs required to interpretate the analytical information detected were built. Experimental conditions to characterize glass samples without secondary effects were defined; and the influence of some leaching parameters was studied to describe the first stages of aqueous corrosion of borosilicate glasses [fr

Corrosion behavior of Cu during graphene growth by CVD

International Nuclear Information System (INIS)

Dong, Yuhua; Liu, Qingqing; Zhou, Qiong

2014-01-01

Highlights: • Graphene films were deposited on the Cu by chemical vapor deposition method. • Annealing affects the corrosion property of Cu. • Graphene films improve corrosion performance of Cu for a short period of time. - Abstract: The corrosion performance of Cu samples may be affected by annealing at high temperatures during graphene growth via the chemical vapor deposition method. In this study, multiple graphene films were deposited on Cu and characterized by Raman spectroscopy and transmission electron microscopy. The corrosion behavior of Cu immersed in 3.5 wt.% NaCl solution was investigated using electrochemical impedance spectroscopy. The Cu morphology was observed by optical microscopy and scanning electron microscopy. Results indicated that annealing affects the corrosion process of Cu. The presence of graphene films on the Cu substrate improved the corrosion performance of the material for a short period of time

Corrosion Behavior of Brazed Zinc-Coated Structured Sheet Metal

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A. Nikitin

2017-01-01

Full Text Available Arc brazing has, in comparison to arc welding, the advantage of less heat input while joining galvanized sheet metals. The evaporation of zinc is reduced in the areas adjacent to the joint and improved corrosion protection is achieved. In the automotive industry, lightweight design is a key technology against the background of the weight and environment protection. Structured sheet metals have higher stiffness compared to typical automobile sheet metals and therefore they can play an important role in lightweight structures. In the present paper, three arc brazing variants of galvanized structured sheet metals were validated in terms of the corrosion behavior. The standard gas metal arc brazing, the pulsed arc brazing, and the cold metal transfer (CMT® in combination with a pulsed cycle were investigated. In experimental climate change tests, the influence of the brazing processes on the corrosion behavior of galvanized structured sheet metals was investigated. After that, the corrosion behavior of brazed structured and flat sheet metals was compared. Because of the selected lap joint, the valuation of damage between sheet metals was conducted. The pulsed CMT brazing has been derived from the results as the best brazing method for the joining process of galvanized structured sheet metals.

Corrosion technology. V. 1

International Nuclear Information System (INIS)

Khan, I.H.

1989-01-01

This book has been produced for dissemination of information on corrosion technology, corrosion hazards and its control. Chapter one of this book presents an overall view of the subject and chapter 2-5 deals with electrochemical basics, types of corrosion, pourbaix diagrams and form of corrosion. The author explains polarization/kinetics of corrosion, passivity, aqueous corrosion and corrosion testing and monitoring in 6-11 chapters. The author hopes it will provide incentive to all those interested in the corrosion technology. (A.B.)

Research on A3 steel corrosion behavior of basic magnesium sulfate cement

Science.gov (United States)

Xing, Sainan; Wu, Chengyou; Yu, Hongfa; Jiang, Ningshan; Zhang, Wuyu

2017-11-01

In this paper, Tafel polarization technique is used to study the corrosion behavior of A3 steel basic magnesium sulfate, and then analyzing the ratio of raw materials cement, nitrites rust inhibitor and wet-dry cycle of basic magnesium sulfate corrosion of reinforced influence, and the steel corrosion behavior of basic magnesium sulfate compared with magnesium oxychloride cement and Portland cement. The results show that: the higher MgO/MgSO4 mole ratio will reduce the corrosion rate of steel; Too high and too low H2O/MgSO4 mole ratio may speed up the reinforcement corrosion effect; Adding a small amount of nitrite rust and corrosion inhibitor, not only can obviously reduce the alkali type magnesium sulfate in the early hydration of cement steel bar corrosion rate, but also can significantly reduce dry-wet circulation under the action of alkali type magnesium sulfate cement corrosion of reinforcement effect. Basic magnesium sulfate cement has excellent ability to protect reinforced, its long-term corrosion of reinforcement effect and was equal to that of Portland cement. Basic magnesium sulfate corrosion of reinforced is far below the level in the MOC in the case.

Phytochemicals as Green Corrosion Inhibitors in Various Corrosive ...

African Journals Online (AJOL)

There is an intensive effort underway to develop new plant origin corrosion inhibitors for metal subjected to various environmental conditions. These efforts have been motivated by the desire to replace toxic inhibitors used for mitigation of corrosion of various metals and alloys in aqueous solutions. Plants represent a class ...

Chromium steel corrosion rates and mechanisms in aqueous nickel chloride at 300C

International Nuclear Information System (INIS)

Forrest, J.E.; Broomfield, J.P.; Mitra, P.K.

1985-01-01

Rapid corrosion of PWR steam generator carbon steel support structures and consequential denting of steam generator tubes led to investigation of alternative support designs and materials. In recent designs of steam generators the carbon steel drilled hole tube support plate has been replaced by one of quatrefoil or trefoil shape to minimize the contact area. These plates are now made of more corrosion resistant chromium steel (approx. 12%Cr) to ensure that they are less vulnerable to attack in the event of adverse boiler water chemistry. This study was initiated to examine the corrosion behavior of a range of chromium steels in the acid chloride environments characteristic of tube/support plate crevices under adverse boiler water conditions. Objectives of the study were to: 1) determine the relative susceptibility of candidate tube support plate steels to acid chloride corrosion; 2) investigate the corrosion product morphology and its relationship to the corrosion mechanism; 3) determine the effect of environment aggressiveness on 12%Cr (A405) steel corrosion rates and mechanisms; and 4) investigate the effect of restraint stress/environment on denting potential of A405. Experimental method and results are discussed

Corrosion behavior of zinc-nickel alloy electrodeposited coatings

Energy Technology Data Exchange (ETDEWEB)

Fabri Miranda, F.J. [USIMINAS, Ipatinga, Minas Gerais (Brazil); Margarit, I.C.P.; Mattos, O.R.; Barcia, O.E. [UFRJ, Rio de Janeiro (Brazil); Wiart, R. [Univ. Pierre et M. Curie, Paris (France)

1999-08-01

Various types of zinc-electrocoated steel sheets are used to improve the durability of car bodies. Among these coatings, the Zn-Ni alloy has higher corrosion resistance than pure Zn, as well as better welding and painting properties. The corrosion mechanism of the Zn-Ni alloy has been investigated mainly on the basis of accelerated tests and electrochemical measurements. There are few data about long-term corrosion tests. In the present study, the behavior of unpainted Zn-Ni alloy coated steel was studied during 3 years of exposure in industrial and marine environments. Electrochemical impedance spectroscopy (EIS) and surface analysis (scanning electron microscopy [SEM] and Auger electron spectroscopy [AES]) were the experimental techniques used. Long-term atmospheric corrosion mechanism of Zn-Ni coatings was discussed and compared with that proposed based on short-term tests.

Corrosion behavior of duplex polyaniline/epoxy coating on mild steel in 3% NaCl

Directory of Open Access Journals (Sweden)

Gvozdenović Milica M.

2005-01-01

Full Text Available The corrosion behavior and thermal stability of epoxy coatings electrodeposited on mild steel and on mild steel with electrochemically deposited polyaniline (PANI film were investigated by electrochemical impedance spectroscopy (EIS and thermo gravimetric analysis (TGA. The aim of the paper was to present new findings on the corrosion protection of mild steel by a duplex PANI/-epoxy coating in 3% NaCI solution and to determine the effect of thin PANI film on the protective properties of the coating. PANI film was deposited electrochemically on mild steel from an aqueous solution of 0.5 mol dm"3 sodium benzoate and 0.1 mol dm"3 aniline at a constant current density of 1.5 mA cm"2. Non-pigmented epoxy coatings on mild steel and on mild steel with PANI film were obtained by cathodic electrode position at constant voltage and stirring conditions. The resin concentration in the electrode position bath was 10 wt.% solid dispersion in water at pH 5.7. The applied voltage was 250 V, the temperature 26°C and the deposition time 3 min. It was shown that thin PANI film could be used to modify the surface of mild steel prior to epoxy coating deposition, due to the increased corrosion protection of a duplex PANI/epoxy coating comparing to an epoxy coating on mild steel in 3% NaCl solution.

Effect of compression deformation on the microstructure and corrosion behavior of magnesium alloys

International Nuclear Information System (INIS)

Snir, Y.; Ben-Hamu, G.; Eliezer, D.; Abramov, E.

2012-01-01

Highlights: ► Metallurgical features (mainly twinning, dislocation accumulation, and dynamic recrystallization). ► The thermo-mechanical state (amount of deformation and its temperature). ► The corrosion behavior of wrought Mg-alloys. This correlation was emphasized by the mechanical behavior measured through micro-hardness. ► Microstructural changes during deformation, and potentio-dynamic corrosion tests were correlated. - Abstract: The effect of deformation on the corrosion and mechanical behavior of wrought Mg-alloys AZ31, AM50, and ZK60 was investigated. The materials’ behavior was correlated to the changes in metallurgical features, during compression, into different amounts of deformation at three temperatures: 250° C, 280° C, and 350° C. The metallurgical features were monitored by optical microscope, scanning electron microscope (SEM), and transmission electron microscopy (TEM). It was observed that there is a very strong correlation between three features: 1. metallurgical features (mainly twinning, dislocation accumulation, and dynamic recrystallization); 2. The thermo-mechanical state (amount of deformation and its temperature); and 3. The corrosion behavior of wrought Mg-alloys. This correlation was emphasized by the mechanical behavior measured through micro-hardness. Microstructural changes during deformation, and potentio-dynamic corrosion tests were correlated. These results show that studies on the effect of thermo-mechanical state (related to the microstructure) on the corrosion behavior of wrought Mg-alloys are essential in order to optimize their applicability to plastic forming processes.

Effect of Elemental Sulfur and Sulfide on the Corrosion Behavior of Cr-Mo Low Alloy Steel for Tubing and Tubular Components in Oil and Gas Industry.

Science.gov (United States)

Khaksar, Ladan; Shirokoff, John

2017-04-20

The chemical degradation of alloy components in sulfur-containing environments is a major concern in oil and gas production. This paper discusses the effect of elemental sulfur and its simplest anion, sulfide, on the corrosion of Cr-Mo alloy steel at pH 2 and 5 during 10, 20 and 30 h immersion in two different solutions. 4130 Cr-Mo alloy steel is widely used as tubing and tubular components in sour services. According to the previous research in aqueous conditions, contact of solid sulfur with alloy steel can initiate catastrophic corrosion problems. The corrosion behavior was monitored by the potentiodynamic polarization technique during the experiments. Energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) have been applied to characterize the corrosion product layers after each experiment. The results show that under the same experimental conditions, the corrosion resistance of Cr-Mo alloy in the presence of elemental sulfur is significantly lower than its resistance in the presence of sulfide ions.

The effects of bacteria on the corrosion behavior of carbon steel in compacted bentonite

International Nuclear Information System (INIS)

Nishimura, T.; Wada, R.; Nishimoto, H.; Fujiwara, K.; Taniguchi, N.; Honda, A.

1999-10-01

As a part of evaluation of corrosion life of carbon steel overpack, the experimental studies have been performed on the effects of bacteria on the corrosion behavior of carbon steel in compacted bentonite using iron bacteria (IB) as a representative oxidizing bacteria and sulphur reducing bacteria (SRB) as a representative reducing bacteria. The results of the experimental studies showed that; The activity of SRB was low in compacted bentonite in spite of applying suitable condition for the action of bacteria such as temperature and nutritious solution. Although the corrosion behavior of carbon steel was affected by the existence of bacteria in simple solution, the corrosion rates of carbon steel in compacted bentonite were several μ m/year -10 μ m/year irrespective of coexistence of bacteria and that the corrosion behavior was not affected by the existence of bacteria. According to these results, it was concluded that the bacteria would not affect the corrosion behavior of carbon steel overpack under repository condition. (author)

Investigation of magnetic, mechanical and microfailure behavior of ARMCO-type low carbon steel corroded in 3.5% NaCl-aqueous solution

International Nuclear Information System (INIS)

Ioakeimidis, E.K.; Kytopoulos, V.N.; Hristoforou, E.

2013-01-01

The corrosion effects of 3.5% NaCl aqueous solution on the tensile mechanical, micromagnetic Barkhausen emission (MBE) and microfailure behavior of low carbon steel were investigated. At first it was found that this steel shows a dramatic and consistent decrease of its ductility with time of corrosion. The ductility reduction as well as microfailure features obtained by Scanning Electron Microscopy (SEM)-fractographic analysis yields an acceptable evidence for the occurrence of the Hydrogen Environmental Embrittlement (HEE) phenomenon during the corrosion process. During tensile straining the MBE-signal increases monotically at an average constant rate towards necking point. This rate shows tendency to increase with corrosion time fact which helped to establish the existence of a corrosion-induced micromagnetic hardening rate effect. It was shown that the main contribution to this effect should be attributed primarily to the combined effect of the HEE and dislocation multiplication and to a lower extent to the formed magnetite (Fe 3 O 4 ) surface layers. Necking plasticity and MBE were correlated on the basis of combined stress bias and microvoid/microcracking-induced creation and rearangement of magnetic domains

Investigation of magnetic, mechanical and microfailure behavior of ARMCO-type low carbon steel corroded in 3.5% NaCl-aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Ioakeimidis, E.K., E-mail: evankostioa@gmail.com [Laboratory of Physical Metallurgy and Materials Technology, School of Mining and Metallurgical Engineering, N. T. U. A., Iroon Polytechniou 5, TK 157 73, Zografou Campus, Athens (Greece); Kytopoulos, V.N., E-mail: viktorkytopoulos@gmail.com [Laboratory of Strength of Materials and SEM, School of Applied Mathematics and Physical Science, N. T. U. A., Iroon Polytechniou 5, TK 157 73, Zografou Campus, Athens (Greece); Hristoforou, E., E-mail: eh@metal.ntua.gr [Laboratory of Physical Metallurgy and Materials Technology, School of Mining and Metallurgical Engineering, N. T. U. A., Iroon Polytechniou 5, TK 157 73, Zografou Campus, Athens (Greece)

2013-10-20

The corrosion effects of 3.5% NaCl aqueous solution on the tensile mechanical, micromagnetic Barkhausen emission (MBE) and microfailure behavior of low carbon steel were investigated. At first it was found that this steel shows a dramatic and consistent decrease of its ductility with time of corrosion. The ductility reduction as well as microfailure features obtained by Scanning Electron Microscopy (SEM)-fractographic analysis yields an acceptable evidence for the occurrence of the Hydrogen Environmental Embrittlement (HEE) phenomenon during the corrosion process. During tensile straining the MBE-signal increases monotically at an average constant rate towards necking point. This rate shows tendency to increase with corrosion time fact which helped to establish the existence of a corrosion-induced micromagnetic hardening rate effect. It was shown that the main contribution to this effect should be attributed primarily to the combined effect of the HEE and dislocation multiplication and to a lower extent to the formed magnetite (Fe{sub 3}O{sub 4}) surface layers. Necking plasticity and MBE were correlated on the basis of combined stress bias and microvoid/microcracking-induced creation and rearangement of magnetic domains.

The effect of some metallurgical factors on the corrosion behaviour of austenitic stainless steels in 3% NaCl aqueous solutions

International Nuclear Information System (INIS)

El-Sayed, A.A.; Morsy, S.M.; El-Raghy, S.M.

1979-01-01

The effect of cold work and subsequent heat treatment on the corrosion behaviour of austenitic stainless steels in 3% NaCl aqueous solutions was studied. Cold work was found to increase the corrosion rate, and heat treatment at 1050 C followed by water-quenching was found reduce to the rate of attack. The increase in the corrosion rate accompanied with a shift in the less noble direction of the steady state potential, an increase in the exchange current density and a decrease in the value of the activation energy. The results indicated that the corrosion potentials are less noble than the critical potentials for pitting, and they are discussed in terms of a simple dissolution process. A correlation is made between the corrosion rate, as expresses in weight loss, and the electrode properties of the corroding material

Corrosion/95 conference papers

International Nuclear Information System (INIS)

Anon.

1995-01-01

The papers in this conference represent the latest technological advances in corrosion control and prevention. The following subject areas are covered: cathodic protection in natural waters; materials for fossil fuel combustion and conversion systems; modern problems in atmospheric corrosion; innovative ideas for controlling the decaying infrastructure; deposits and their effects on corrosion in industry; volatile high temperature and non aqueous corrosion inhibitors; corrosion of light-weight and precoated metals for automotive application; refining industry corrosion; corrosion in pulp and paper industry; arctic/cold weather corrosion; materials selection for waste incinerators and associated equipment; corrosion measurement technology; environmental cracking of materials; advancing technology in the coating industry; corrosion in gas treating; green inhibition; recent advances in corrosion control of rail equipment; velocity effects and erosion corrosion in oil and gas production; marine corrosion; corrosion of materials in nuclear systems; underground corrosion control; corrosion in potable and industrial water systems in buildings and its impact on environmental compliance; deposit related boiler tube failures; boiler systems monitoring and control; recent developments and experiences in reactive metals; microbiologically influenced corrosion; corrosion and corrosion control for steel reinforced concrete; international symposium on the use of 12 and 13 Cr stainless steels in oil and gas production environments; subsea corrosion /erosion monitoring in production facilities; fiberglass reinforced pipe and tubulars in oilfield service; corrosion control technology in power transmission and distribution; mechanisms and methods of scale and deposit control; closing the loop -- results oriented cooling system monitoring and control; and minimization of aqueous discharge

Effect of microstructure on corrosion behavior of Ag-30Cu-27Sn alloy in vitro media

International Nuclear Information System (INIS)

Salehisaki, Mehdi; Aryana, Maryam

2014-01-01

Highlights: • High cooling rates decrease the number of Ag intermetallic particles in Cu-rich phase. • Increasing cooling rate improves corrosion behavior of Ag-30Cu-27Sn dental alloy. • Cathode/anode ratio in Cu-rich phases determines the corrosion behavior of alloy. - Abstract: In the present work, three simple heat treatment cycles were used to study the effects of microstructure on electrochemical corrosion behavior of Ag-30Cu-27Sn dental alloy. The electrochemical impedance spectroscopy (EIS) measurements and potentiodynamic polarization tests were carried out to investigate the corrosion behavior of as-cast and heat treated samples in synthetic saliva solution. The presence of intermetallic compounds were studied by X-ray diffraction method (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray detector (EDAX). The microstructural observations and electrochemical corrosion results revealed that, increasing the cooling rate improves the corrosion behavior of under investigation samples. Improvement of the corrosion behavior is attributed to reducing the area of fine distributed Ag 3 Sn islands in the Cu-rich matrix which decrease the cathode/anode ratio of microgalvanic cells

Effect of silicon carbide addition on the corrosion behavior of powder metallurgy Cu−30Zn brass in a 3.5 wt% NaCl solution

Energy Technology Data Exchange (ETDEWEB)

Almomani, Mohammed Ali, E-mail: maalmomani7@just.edu.jo [Department of Industrial Engineering, Jordan University of Science and Technology, P. O. Box 3030, Irbid 22110 (Jordan); Tyfour, Wa' il Radwan, E-mail: wrtyfou@just.edu.jo [Department of Industrial Engineering, Jordan University of Science and Technology, P. O. Box 3030, Irbid 22110 (Jordan); Nemrat, Mohammed Hani, E-mail: mohammednemrat@yahoo.com [Department of Mechanical Engineering, Institute of Applied Technology, Abu Dhabi (United Arab Emirates)

2016-09-15

A study was made to evaluate the corrosion behavior when Cu−30Zn alloy is reinforced with different weight fractions of silicon carbide (SiC) particles in a simulated sea solution (3.5 wt% NaCl aqueous solution). The composites were produced via powder metallurgy (PM) route. For the sake of comparison, the corrosion behaviors of unreinforced and reinforced alloy were examined. Electrochemical measurements (potentiodynamic testing) showed that the corrosion rate of the composites decreased with increase of SiC weight percentages, as a result of weak microgalvanic couple between reinforcement particles and Cu−30Zn matrix, and the low possibility of intermetallic phases formation. ANOVA test indicated that the variations of corrosion rate of the composites upon changing weight percentages of SiC particles are statistically significant. Polarization curves showed that the passive film tends to be less stable, and the potential difference between passivation and free corrosion points increased with increase of SiC weight percentages, as SiC cathodically protect the matrix material by sacrificial anodic dissolution of crevice regions about reinforcement particles. Scanning Electron Microscope (SEM) images of the sample's surfaces before and after testing are in agreement with the electrochemical results. - Highlights: • Effect of adding SiC on both uniform and localized corrosion of Cu−30Zn alloy is studied. • Reinforcing Cu−30Zn with nonconductive SiC particles decreases its tendency to uniform and localized corrosion. • Reinforcement particles cathodically protect the matrix material, and retard pit propagation to the matrix.

In vitro corrosion behavior of bioceramic, metallic, and bioceramic-metallic coated stainless steel dental implants.

Science.gov (United States)

Fathi, M H; Salehi, M; Saatchi, A; Mortazavi, V; Moosavi, S B

2003-05-01

The most common metals and alloys used in dentistry may be exposed to a process of corrosion in vivo that make them cytotoxic. The biocompatibility of dental alloys is primarily related to their corrosion behavior. The aim of this work was to evaluate the corrosion behavior and thus the biocompatibility of the uncoated and coated stainless steels and compare the effect of type of coatings on corrosion behavior. Three types of coatings, hydroxyapatite (HA), titanium (Ti), and a double-layer HA/Ti on AISI 316L stainless steel were made. HA coating was produced using plasma-spraying technique and Ti coating was made using physical vapor deposition process. In order to perform a novel double-layer composite coating, a top layer of HA was plasma-sprayed over a physical vapor deposited Ti layer on AISI 316L stainless steel. Structural characterization techniques including XRD, SEM and EDX were used to investigate the microstructure, morphology and crystallinity of the coatings. Electrochemical potentiodynamic tests were performed in physiological solutions in order to determine and compare the corrosion behavior of the coated and uncoated specimens as an indication of biocompatibility. Double-layer HA/Ti coating on AISI 316L SS had a positive effect on improvement of corrosion behavior. The decrease in corrosion current densities was significant for these coated specimens and was much lower than the values obtained for uncoated and single HA coated specimens. Ti coating on AISI 316L SS also has a beneficial effect on corrosion behavior. The results were compared with the results of corrosion behavior of HA coated commercially pure titanium (cpTi) and uncoated cpTi. These results demonstrated that the double-layer HA/Ti coated 316L SS can be used as an endodontic implant and two goals including improvement of corrosion resistance and bone osteointegration can be obtained simultaneously.

Modeling of atmospheric corrosion environments and its application to constant dew-point corrosion test; Yagai taiki fushoku kankyo no modeling to sore ni motozuku teirotengata saikuru fushoku shikenho no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Muto, I. [Nippon Steel Corp., Tokyo (Japan)] Sugimoto, K. [Tohoku Univ., Sendai (Japan)

1998-08-15

Recently, stainless steel is increasing its demand for corrosion resistant building materials. Then, as it is necessary to develop and accelerating testing method capable of accurately estimating weatherability at sea side area, such testing method has no been developed yet because of difficulty to quantify corrosive environment relating to atmospheric corrosion phenomenon. As air temperature and relative humidity in outdoor change in complex, specific temperature and relative humidity cannot be used for their representative values. And, construction of corrosive factors such as sea salt particles, and so on are also much different at each area. However, at coastal area, a dew water dissolving the sea salt particles, so called droplets of chlorides aqueous solution is formed onto material surface. Then, in this study, on a base of drying and humidity absorption behavior and daily change behavior of temperature and humidity in outdoor, modeling of atmospheric corrosion environment was tried. An accelerating testing method according to this modeling was developed, long-term weathering test was compared with the corrosion behavior of the same steel, and validity of a new accelerating testing method was evaluated. 22 refs., 12 figs., 2 tabs.

Corrosion behavior of magnesium-graphene composites in sodium chloride solutions

Directory of Open Access Journals (Sweden)

Muhammad Rashad

2017-09-01

Full Text Available Coating of graphene and graphene/polymer composites on metals improves the corrosion resistance of metal substrates. On other hand, graphene embedded inside metal (especially Mg matrices increases or decreases corrosion, is a crucial factor and must be explored. In present study, electrochemical behaviors of magnesium alloys (AZ31 and AZ61 and their composites reinforced with graphene nanoplatelets (GNPs were carried out in 3.5% NaCl solution by polarization method. The surface morphology of composites before and after corrosion tests were analyzed using scanning electron microscopy. Experimental results revealed that presence of graphene nanoplatelets in different matrices decrease corrosion resistance of composites. This may be attributed to presence of graphene nanoplatelets which activates the corrosion of magnesium/alloys due to the occurrence of galvanic corrosion and this effect increases with increasing graphene nanoplatelets content. Further, an appropriate model describing the corrosion mechanism was proposed.

The effect of heat treatments on the corrosion behavior of Zircaloy-4

International Nuclear Information System (INIS)

Zhou Bangxin; Zhao Wenjin; Miao Zhi; Pan Shufang; Li Cong; Jiang Yourong

1996-06-01

The effect of penultimate annealing temperature and cooling rate on the corrosion behavior of Zircaloy-4 cladding tube has been investigated. Both nodular corrosion and uniform corrosion resistance can be improved obviously after changing the heat treatment from the original annealing at 650 degree C to quenching from 830 degree C (upper temperature of alpha phase region or lower temperature of beta phase region). Although the nodular corrosion resistance can be improved obviously after quenching from beta phase, there was a second transition in the variation between weight gain and exposure time, which shows a poor uniform corrosion resistance after a long exposure time during the autoclave tests. The main factor of affecting corrosion behavior is the solid solution contents of Fe and Cr in alpha zirconium rather than the size of second phase particles. About 200 μg/g Fe and Cr super saturated solid solution in alpha zirconium could get good uniform and nodular corrosion resistance, but much more solid solution contents of Fe and Cr in alpha zirconium could bring about a trend toward poor uniform corrosion resistance for long-term exposure time. (14 refs., 10 figs., 1 tab.)

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.

Fabrication and corrosion behavior of fresh porous silicon in sodium hydroxide solution

International Nuclear Information System (INIS)

Lai, Chuan; Li, Xueming; Zhang, Daixiong; Xiang, Zhen; Yang, Wenjing; Guo, Xiaogang

2014-01-01

The corrosion behavior of fresh porous silicon (f-PS) in sodium hydroxide (NaOH) solution in the presence and absence of ethanol was studied by weight loss measurements and scanning electron microscope (SEM) technique. The phenomena and progress of f-PS corrosion in 1.0 M NaOH at 318 K was obtained and described. Weight loss measurements show that the corrosion rate increases with increasing temperature and concentration of NaOH solution. Meanwhile, the corrosion rate first increases with increasing volume ratio of ethanol in 1.0 M NaOH, and then decreases. Additionally, the thermodynamic and kinetic parameters (E a , A, ΔH a and ΔS a ) for f-PS corrosion were obtained and discussed. And the effect factors (T, c and v) of f-PS corrosion in NaOH solution were studied in this paper. - Highlights: • The corrosion behavior of f-PS in NaOH solution was studied for the first time. • Phenomena and progress of f-PS corrosion in NaOH solution was obtained and described. • The effect factors (T, c and v) of f-PS corrosion in NaOH solution were studied. • The kinetic and thermodynamic parameters were obtained and discussed. • The corrosion rate can be improved by adding ethanol into NaOH solution

Corrosion of alloy 22 in phosphate ions effect and chloride containing solutions

International Nuclear Information System (INIS)

Carranza, Ricardo M.

2009-01-01

Alloy 22 belongs to Ni-Cr-Mo family. This alloy resists the most aggressive environments for industrial applications, in oxidizing as well as reducing conditions, because exhibits an excellent uniform and localized corrosion resistance in aqueous solution. Because of its outstanding corrosion resistant, this alloy is one of the candidate to be considered for the outer shell of the canister that would contain high level radioactive nuclear wastes in a geological repository. The aim of this work is to study ion phosphate influence over Alloy 22 corrosion behavior under aggressive conditions, such as high temperature and high ion chloride concentration, where this material might be susceptible to crevice corrosion. Two different types of samples were used: cylinder specimens for uniform corrosion behavior studies and Prismatic Crevice Assembly (PCA) specimens for localized corrosion studies. Electrochemical tests were performed in deaerated aqueous solution of 1 M NaCl and 1 M NaCl with different phosphate additions at 90 C degrees and pH near neutral. The anodic film and corrosion products obtained were studied by SEM/EDS. Cyclic Potentiodynamic Polarization (CPP) curves obtained for uniform corrosion studies, showed an increase of the passivity range in phosphate containing solutions. The passive current value was 1 μA/cm 2 approximately in all the tests. PCA electrochemical tests, that combined a CPP with a potentiostatic polarization step for 2 hours in between the forward and reverse scan, showed crevice corrosion development in some cases. The repassivation potential value, determined by the intersection of the forward and the reverse scan, increased with phosphate addition. A complete crevice corrosion inhibition effect was found for phosphate concentration higher than 0.3 M. These results indicate that the passivity potential range depend on phosphate presence and might be related with the incorporation of the anion in the passive film. Results of the tests

A potentiodynamic study of aluminum-lithium alloys in an aqueous sodium chloride environment

Science.gov (United States)

Tsao, C.-H. T.; Pizzo, P. P.

1985-01-01

The characteristics of the potentiodynamic curves for Al-Li alloys in 3.5 percent NaCl aqueous solution are explained and the electrochemical parameters of the potentiodynamic technique are correlated to observed pitting and intergranular cracking behavior. It is shown that the oxygen content of the sodium chloride electrolyte plays an important role in the electrochemical behavior of Al-Li alloys. The potentiodynamic behavior of the alloys is found to be insensitive to variation in compositional content and heat treatment, both of which affect the stress-corrosion behavior. Stringer oxide particle attack and random pitting are observed. It is shown that alternate-immersion exposure prior to potentiodynamic polarization may offer a means of assessing susceptibility to stress-corrosion cracking.

Corrosion principles and surface modification

International Nuclear Information System (INIS)

Kruger, J.

1982-01-01

This chapter examines the important strategies provided by the newer ideas of corrosion science and engineering that surface modification techniques must utilize to help prevent corrosion, especially the most damaging kind of aqueous corrosion, localized corrosion. Provides a brief introduction to the principles underlying the phenomenon of corrosion in order to use them to discuss surface modification strategies to combat corrosion. Discusses the electrochemistry of corrosion; the thermodynamics of corrosion; the kinetics of corrosion; thermodynamic strategies; and kinetic strategies (formation of more protective passive films; resistance to breakdown; ductility; repassivation)

Corrosion Behavior of SA508 Coupled with and without Magnetite in Chemical Cleaning Environments

International Nuclear Information System (INIS)

Son, Yeong-Ho; Jeon, Soon-Hyeok; Song, Geun Dong; Hur, Do Haeng; Lee, Jong-Hyeon

2017-01-01

To mitigate these problems, chemical cleaning process has been widely used. However, the chemical cleaning solution can affect the corrosion of SG structural materials as well as the magnetite dissolution. During the chemical cleaning process, the galvanic corrosion between SG materials and magnetite is also anticipated because they are in electrical connection. However, the corrosion measurement or monitoring for the materials has been performed without consideration of galvanic effect coupled with magnetite during the chemical cleaning process. In this study, the effect of temperature and EDTA concentration on the corrosion behavior of SA508 tubesheet material with and without magnetite was studied in chemical cleaning solutions. The galvanic corrosion behavior between SA508 and magnetite is predicted by using the mixed potential theory and its effect on the corrosion rate of SA508 is also discussed. By newly designed immersion test, it was confirmed that the extent of galvanic corrosion effect between SA508 and magnetite increased with increasing temperature and EDTA concentration. The galvanic corrosion behavior of SA508 coupled with magnetite in chemical cleaning environments was predicted by the mixed potential theory and verified by ZRA and LP technique. Galvanic coupling increased the corrosion rate of SA508 due to the shift in its potential to the anodic direction. Therefore, the galvanic corrosion effect between SA508 and magnetite should be considered when the corrosion measurement is performed during the chemical cleaning process in steam generators.

Heat Exchanger Tube to Tube Sheet Joints Corrosion Behavior

Directory of Open Access Journals (Sweden)

M. Iancu

2013-03-01

Full Text Available Paper presents the studies made by the authors above the tube to tube sheet fittings of heat exchanger with fixed covers from hydrofining oil reforming unit. Tube fittings are critical zones for heat exchangers failures. On a device made from material tube and tube sheet at real joints dimensions were establish axial compression force and traction force at which tube is extracted from expanded joint. Were used two shapes joints with two types of fittings surfaces, one with smooth hole of tube sheet and other in which on boring surface we made a groove. From extracted expanded tube zones were made samples for corrosion tests in order to establish the corrosion rate, corrosion potential and corrosion current in working mediums such as hydrofining oil and industrial water at different temperatures. The corrosion rate values and the temperature influence are important to evaluate joints durability and also the results obtained shows that the boring tube sheet shape with a groove on hole tube shape presents a better corrosion behavior then the shape with smooth hole tube sheet.

Corrosion phenomena on alloy 625 in aqueous solutions containing hydrochloric acid and oxygen under subcritical and supercritical conditions

International Nuclear Information System (INIS)

Boukis, N.; Kritzer, P.

1997-01-01

Supercritical Water Oxidation (SCWO) is a very effective process to destroy hazardous aqueous wastes containing organic contaminants. The main target applications in the USA are the destruction of DOD and DOE wastes such as rocket fuels and explosives, warfare agents and organics present in low level radioactive liquid wastes. Alloy 625 is frequently used as reactor material for Supercritical Water Oxidation (SCWO) applications. This is due to the favorable combination of mechanical properties, corrosion resistance, price and availability. Nevertheless, the corrosion of alloy 625 like the corrosion of other Ni-base alloys during oxidation of hazardous organic waste containing chloride proceeds too fast and is a major problem in SCWO applications. In these experiments high pressure, high-temperature resistant tube reactors made of alloy 625 were used as specimens. They were exposed to SCWO conditions, without organics, at temperatures up to 500 C and pressures up to 37 MPa for up to 150 h. Simultaneously, coupons also made from alloy 625 are exposed inside the test tubes. The most important corrosion problem for alloy 625 is pitting and intercrystalline corrosion at temperatures near the critical temperature, i.e. in the preheater and cooling sections of the test tubes. Under certain conditions, stress corrosion cracking appears and leads to premature failure of the test reactors. The corrosion products were insoluble in supercritical water and formed thick layers in the supercritical part of the reactor. Under these layers only minor corrosion occurred. 33 refs

Corrosion behavior of silicon nitride in sodium hydroxide solutions at 175 deg C

International Nuclear Information System (INIS)

Strecker, Kurt; Robin, Alain; Vernilli, Fernando; Ribeirao, Sebastiao

1996-01-01

This paper presents results of the corrosion of Si 3 N 4 in aqueous solutions of NaOH (37,5%) at 15 deg C.The corrosive attack was evaluated from the weight loss of the samples.A constant rate was observed, signifying that the corrosion rate depends only on the velocity of the dissolution by the NaOH solution. The corrosion rates of Si 3 N 4 doped with Y 2 O 3 / Si O 2 and a rare earth concentrate/Si O 2 yielded 1,19 x 10 -3 g cm -2 h -1 and 0,78 x 10 -3 g cm -2 h -1 , respectively. Analysis of the corroded samples by electronic microscopy revealed that the glassy intergranular phase is dissolved by the alkaline solution, leaving a skeleton of inter linked β - Si 3 N 4 grains. The mechanical resistance of the corroded samples was determined and demonstrated mechanical degradation of the material. (author)

Corrosion behavior of carbon steel in wet Na-bentonite medium

International Nuclear Information System (INIS)

Yeon, Jae-Won; Ha, Young-Kyoung; Choi, In-Kyu; Chun, Kwan-Sik

1996-01-01

Corrosion behaviors of carbon steel in wet Na-bentonite medium were studied. Corrosion rate of carbon steel in wet bentonite was measured to be 20 μm/yr at 25 deg C using the AC impedance technique. This value is agreed with that obtained by weight loss at 40 deg C for 1 year. The effect of bicarbonate ion on the corrosion of carbon steel in wet bentonite was also evaluated. The carbon steels in wet bentonite having 0.001, 0.01, and 0.1 M concentration of bicarbonate ion gave corrosion rates of 20, 8, and 0.2 μm/yr, respectively. Corrosion potentials of specimens were also measured and compared with the AC impedance results. Both results indicated that bicarbonate ion could effectively reduce the corrosion rate of carbon steels in bentonite due to the formation of protective layer on the carbon steel. (author)

Electrochemical corrosion behavior of gas atomized Al–Ni alloy powders

International Nuclear Information System (INIS)

Osório, Wislei R.; Spinelli, José E.; Afonso, Conrado R.M.; Peixoto, Leandro C.; Garcia, Amauri

2012-01-01

Highlights: ► Spray-formed Al–Ni alloy powders have cellular microstructures. ► Porosity has no deleterious effect on the electrochemical corrosion behavior. ► Better pitting corrosion resistance is related to a fine powder microstructure. ► A coarse microstructure can be related to better general corrosion resistance. - Abstract: This is a study describing the effects of microstructure features of spray-formed Al–Ni alloy powders on the electrochemical corrosion resistance. Two different spray-formed powders were produced using nitrogen (N 2 ) gas flow (4 and 8 bar were used). Electrochemical impedance spectroscopy (EIS), potentiodynamic anodic polarization techniques and an equivalent circuit analysis were used to evaluate the electrochemical behavior in a dilute 0.05 M NaCl solution at room temperature. It was found that a N 2 gas pressure of 8 bar resulted in a microstructure characterized by a high fraction of small powders and fine cell spacings, having improved pitting potential but higher corrosion current density when compared with the corresponding results of a coarser microstructure array obtained under a lower pressure. A favorable effect in terms of current density and oxide protective film formation was shown to be associated with the coarser microstructure, however, its pitting potential was found to be lower than that of the finer microstructure.

The corrosion and stress corrosion cracking behavior of a novel alumina-forming austenitic stainless steel in supercritical water

Energy Technology Data Exchange (ETDEWEB)

Sun, Hongying [School of Mechanical Engineering, Anyang Institute of Technology, Anyang 455002 (China); Yang, Haijie [Modern Engineering Training Center, Anyang Institute of Technology, Anyang 455002 (China); Wang, Man [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Giron-Palomares, Benjamin [School of Mechanical Engineering, Anyang Institute of Technology, Anyang 455002 (China); Zhou, Zhangjian, E-mail: zhouzhj@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, Lefu [School of Nuclear Science and Engineering, Shanghai Jiaotong University, No 800 Dongchuan Road, Shanghai (China); Zhang, Guangming, E-mail: ustbzgm@163.com [School of Automobile & Transportation, Qingdao Technological University, Qingdao 266520 (China)

2017-02-15

The general corrosion and stress corrosion behavior of Fe-27Ni-15Cr-5Al-2Mo-0.4Nb alumina-forming austenitic (AFA) steel were investigated in supercritical water under different conditions. A double layer oxide structure was formed: a Fe-rich outer layer (Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4}) and an Al-Cr-rich inner layer. And the inner layer has a low growth rate with exposing time, which is good for improvement of corrosion resistance. Additionally, some internal nodular Al-Cr-rich oxides were also observed, which resulted in a local absence of inner layer. Stress corrosion specimens exhibited a combination of high strength, good ductility and low susceptibility. The stress strength and elongation was reduced by increasing temperature and amount of dissolved oxygen. In addition, the corresponding susceptibility was increased with decreased temperatures and increased oxygen contents. - Highlights: • The general corrosion and SCC in SCW of the AFA steel have been limited reported. • Fe-rich inner and Al-Cr-rich outer layers are formed in 650 °C/25 MPa/10 ppb SCW. • The SCC behavior exhibits a combination of high strength and good ductility. • Strength and elongation are lowered by increase of temperature and oxygen content. • The AFA steel shows low SCC susceptibility and a superior corrosion resistance.

The corrosion and stress corrosion cracking behavior of a novel alumina-forming austenitic stainless steel in supercritical water

International Nuclear Information System (INIS)

Sun, Hongying; Yang, Haijie; Wang, Man; Giron-Palomares, Benjamin; Zhou, Zhangjian; Zhang, Lefu; Zhang, Guangming

2017-01-01

The general corrosion and stress corrosion behavior of Fe-27Ni-15Cr-5Al-2Mo-0.4Nb alumina-forming austenitic (AFA) steel were investigated in supercritical water under different conditions. A double layer oxide structure was formed: a Fe-rich outer layer (Fe 2 O 3 and Fe 3 O 4 ) and an Al-Cr-rich inner layer. And the inner layer has a low growth rate with exposing time, which is good for improvement of corrosion resistance. Additionally, some internal nodular Al-Cr-rich oxides were also observed, which resulted in a local absence of inner layer. Stress corrosion specimens exhibited a combination of high strength, good ductility and low susceptibility. The stress strength and elongation was reduced by increasing temperature and amount of dissolved oxygen. In addition, the corresponding susceptibility was increased with decreased temperatures and increased oxygen contents. - Highlights: • The general corrosion and SCC in SCW of the AFA steel have been limited reported. • Fe-rich inner and Al-Cr-rich outer layers are formed in 650 °C/25 MPa/10 ppb SCW. • The SCC behavior exhibits a combination of high strength and good ductility. • Strength and elongation are lowered by increase of temperature and oxygen content. • The AFA steel shows low SCC susceptibility and a superior corrosion resistance.

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.

Radiation Corrosion of in-reactor and nuclear Waste Canister overpack Materials

International Nuclear Information System (INIS)

Kim, Young Jin

1986-01-01

The effect of γ-radiation on the corrosion processes in aqueous environments has been reviewed, with particular emphasis on radiolysis of aqueous solutions and its effect on the corrosion mechanisms. A potentially critical feature of the corrosion environment would be the presence of a high γ-radiation field which could have a significant effect on corrosion processes. The radiation of an aqueous solution causes radiolysis of the water to produce a variety of products, such as H, OH, H 2 , O 2 , H 2 O 2 , etc. The radiolysis products would alter its redox chemistry, which could change the kinetics of both the initiation and propagation of corrosion processes. Similar, though not necessarily identical, effects are expected at a metal/solution interface. The possibility of different interactions at the interface is particularly relevant in determining the effects of radiation on corrosion processes. This review is divided into two section in terms of the action of radiation on: (1) the aqueous environment and (2) the corrosion process. The first part of this review focuses on the effects of γ-radiation on radiolysis of the aqueous environments, and the effects of γ-radiation on the metallic corrosion processes will be discussed later

Mechanisms of Copper Corrosion in Aqueous Environments. A report from the Swedish National Council for Nuclear Waste's scientific workshop, on November 16, 2009

International Nuclear Information System (INIS)

2010-01-01

In 2010 the Swedish Nuclear Fuel and Waste Management Company, SKB, plans to submit its license application for the final repository of spent nuclear fuel. The proposed method is the so-called KBS-3 method and implies placing the spent nuclear fuel in copper canisters, surrounded by a buffer of bentonite clay, at 500 m depth in the bedrock. The site selected by SKB to host the repository is located in the municipality of Oesthammar on the Swedish east coast. The copper canister plays a key role in the design of the repository for spent nuclear fuel in Sweden. The long-term physical and chemical stability of copper in aqueous environments is fundamental for the safety evolution of the proposed disposal concept. However, the corrosion resistance of copper has been questioned by results obtained under anoxic conditions in aqueous solution. These observations caused some head-lines in the Swedish newspapers as well as public and political concerns. Consequently, the Swedish National Council for Nuclear Waste organized a scientific workshop on the issue 'Mechanisms of Copper Corrosion in Aqueous Environments'. The purpose of the workshop was to address the fundamental understanding of the corrosion characteristics of copper regarding oxygen-free environments, and to identify what additional information is needed to assess the validity of the proposed corrosion mechanism and its implication on the containment of spent nuclear fuel in a copper canister. This seminar report is based on the presentations and discussions at the workshop. It also includes written statements by the members of the expert panel

Thermodynamic studies on corrosion inhibition of aqueous solutions of amino/carboxylic acids toward copper by EMF measurement

International Nuclear Information System (INIS)

Spah, Manjula; Spah, Dal Chand; Deshwal, Balraj; Lee, Seungmoon; Chae, Yoon-Keun; Park, Jin Won

2009-01-01

Electromotive force (E) measurements were made on an electrochemical cell [Cu x Hg|CuCl 2 (m) in a solvent S|AgCl-Ag] (where S is a dilute aqueous solution (0.01 m) of amino acid (glycine, alanine, methionine and glutamic acid) or aliphatic carboxylic acid (formic acid, acetic acid, n-butyric acid and glutaric acid)) at 30 deg. C. These measured E values were used to compute the dissociation constants (K 1 and K 2 ) and the degree of dissociation (α 1 and α 2 ) by iterative procedures. The standard cell potential (E o ) and the mean activity coefficient (γ ± ) of CuCl 2 were also determined. The E o data were next used to evaluate the Gibbs energy of transfer (ΔG tr 0 ) of CuCl 2 from water to dilute aqueous solutions of the amino/carboxylic acids. The negative ΔG tr 0 values suggested that these acids act as potential corrosion inhibitors. The magnitudes of ΔG tr 0 values show that the amino acids act as better corrosion inhibitors towards copper than the aliphatic carboxylic acids.

Studies on dissolution characteristics of simulated corrosion products on pressurized water reactor primary coolant loops. Pt.2: Cobalt simulated corrosion product

International Nuclear Information System (INIS)

Li Shan; Zhou Xianyu

1997-01-01

The studies on the dissolution characteristics of simulated corrosion product of cobalt on pressurized water reactor primary coolant loops in aqueous solution of citric acid, hydrogen peroxide and citric acid-hydrogen peroxide have been performed. The results show that the portion of the dissolved simulated corrosion product of cobalt in citric acid aqueous solution clearly increases with a rise in citric acid concentration and is ten times above the corresponding value of iron. The portion of the products that dissolve is the largest at pH 3.00 in the pH range of 2.33∼4.50 and at 70 degree C in the range of 60∼80 degree C. It is shown that the portion of the dissolved simulated corrosion product of cobalt in hydrogen peroxide aqueous solution is smaller than the corresponding value in citric acid, and that the portion of the dissolved simulated corrosion product of cobalt in aqueous solution of hydrogen peroxide-citric acid is larger than the corresponding value in single citric acid aqueous solution

Electrochemical characterization of Zr-based thin film metallic glass in hydrochloric aqueous solution

International Nuclear Information System (INIS)

Chuang, Ching-Yen; Liao, Yi-Chia; Lee, Jyh-Wei; Li, Chia-Lin; Chu, Jinn P.; Duh, Jenq-Gong

2013-01-01

Recently thin film metallic glass represents a class of promising engineering materials for structural applications. In this work, the Zr-based thin film metallic glass (TFMG) was fabricated on the Si and AISI 420 substrates using a Zr–Cu–Ni–Al alloy and pure Zr metal targets by a pulsed DC magnetron sputtering system. The chemical compositions, crystalline structures, microstructures and corrosion behavior in hydrochloric (HCl) aqueous solutions of Zr-based TFMGs were investigated. The results showed that the surface morphologies of Zr-based TFMG were very smooth. A compact and dense structure without columnar structure was observed. The amorphous structure of Zr-based TFMG was characterized by the X-ray diffractometer and transmission electron microscopy analyses. After the potentiodynamic polarization test, the better corrosion resistance was achieved for the Zr-based TFMG coated AISI 420 in 1 mM HCl aqueous solution. Based on the surface morphologies and chemical analysis results of the corroded surfaces, the pitting, crevice corrosion and filiform corrosion were found. The corrosion mechanisms of the Zr-based TFMG were discussed in this work. - Highlights: ► Zr-based thin film metallic glass with amorphous structure. ► Better corrosion resistance of Zr-based thin film metallic glass observed. ► Pitting, crevice and filiform corrosion reactions revealed. ► The Cu-rich corrosion products found in the pit. ► Nanowire and flaky corrosion products formed adjacent to the filiform corrosion path

Electrochemical corrosion behavior of AZ91D alloy in ethylene glycol

International Nuclear Information System (INIS)

Fekry, A.M.; Fatayerji, M.Z.

2009-01-01

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 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.

Corrosion behavior of construction materials for ionic liquid hydrogen compressor

DEFF Research Database (Denmark)

Arjomand Kermani, Nasrin; Petrushina, Irina; Nikiforov, Aleksey Valerievich

2016-01-01

The corrosion behavior of various commercially available stainless steels and nickel-based alloys as possible construction materials for components which are in direct contact with one of five different ionic liquids was evaluated. The ionic liquids, namely: 1-ethyl-3-methylimidazolium triflate, 1...... liquid hydrogen compressor. An electrochemical cell was specially designed, and steady-state cyclic voltammetry was used to measure the corrosion resistance of the alloys in the ionic liquids at 23 °C, under atmospheric pressure. The results showed a very high corrosion resistance and high stability...... for all the alloys tested. The two stainless steels, AISI 316L and AISI 347 showed higher corrosion resistance compared to AISI 321 in all the ionic liquids tested. It was observed that small addition of molybdenum, tantalum, and niobium to the alloys increased the corrosion stability in the ionic liquids...

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.

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.

Improved corrosion behavior of nanocrystalline zinc produced by pulse-current electrodeposition

International Nuclear Information System (INIS)

Youssef, Kh.M.S.; Koch, C.C.; Fedkiw, P.S.

2004-01-01

Pulse electrodeposition was used to produce nanocrystalline (nc) zinc from zinc chloride electrolyte with polyacrylamide and thiourea as additives. Field emission scanning electron microscopy (FESEM) was used to study the grain size and surface morphology of the deposits and X-ray diffraction was used to examine their preferred orientation. Corrosion behavior of the electrodeposited nc zinc in comparison with electrogalvanized (EG) steel in de-aerated 0.5 N NaOH solution was studied using potentiodynamic polarization and impedance measurements. A scanning electron microscope (SEM) was used to characterize the surface morphology of the EG steel before corrosion testing. Surface morphologies of nc zinc deposits and EG steel were also studied after potentiondynamic polarization by SEM. Nanocrystalline zinc (56 nm) with random orientation was produced. The estimated corrosion rate of nc zinc was found to be about 60% lower than that of EG steel, 90 and 229 μA/cm 2 , respectively. The surface morphology of corroded nc zinc was characterized by discrete etch pits, however, uniform corrosion was obtained after potentiodynamic polarization of EG steel. The passive film formed on the nc zinc surface seems to be a dominating factor for the corrosion behavior observed

Corrosion behavior, mechanical properties, and long-term aging of nickel-plated uranium

International Nuclear Information System (INIS)

Dini, J.W.; Johnson, H.R.; Schoenfelder, C.W.

1976-01-01

The behavior of nickel-plated uranium upon exposure to moist nitrogen was evaluated. Plating thicknesses of 0.051 mm (2 mil) were adequate to prevent corrosion. Specimens with thinner coats showed some corrosion and some reduction in mechanical properties during subsequent testing. Plated samples exposed to dry air at ambient pressure for 10 y showed no corrosion and no degradation of mechanical properties. Surface and bulk hydrogen content, as well as free hydrogen generated during the test, were measured to determine the extent of corrosion. Results support an earlier proposed mechanism for uranium corrosion at low humidities

Microscopic Examination of a Corrosion Front in Spent Nuclear Fuel

International Nuclear Information System (INIS)

J.A. Fortner; A.J. Kropf; R.J. Finch; J.C. Cunnane

2006-01-01

Spent uranium oxide nuclear fuel hosts a variety of trace chemical constituents, many of which must be sequestered from the biosphere during fuel storage and disposal. In this paper we present synchrotron x-ray absorption spectroscopy and microscopy findings that illuminate the resultant local chemistry of neptunium and plutonium within spent uranium oxide nuclear fuel before and after corrosive alteration in an air-saturated aqueous environment. We find the plutonium and neptunium in unaltered spent fuel to have a +4 oxidation state and an environment consistent with solid-solution in the UO 2 matrix. During corrosion in an air-saturated aqueous environment, the uranium matrix is converted to uranyl U(VI)O 2 2+ mineral assemblage that is depleted in plutonium and neptunium relative to the parent fuel. At the corrosion front interface between intact fuel and the uranyl-mineral corrosion layer, we find evidence of a thin (∼20 micrometer) layer that is enriched in plutonium and neptunium within a predominantly U 4+ environment. Available data for the standard reduction potentials for NpO 2+ /Np 4+ and UO 2 2+ /U 4+ couples indicate that Np(IV) may not be effectively oxidized to Np(V) at the corrosion potentials of uranium dioxide spent nuclear fuel in air-saturated aqueous solutions. Neptunium is an important radionuclide in dose contribution according to performance assessment models of the proposed U. S. repository at Yucca Mountain, Nevada. A scientific understanding of how the UO 2 matrix of spent nuclear fuel impacts the oxidative dissolution and reductive precipitation of neptunium is needed to predict its behavior at the fuel surface during aqueous corrosion. Neptunium would most likely be transported as aqueous Np(V) species, but for this to occur it must first be oxidized from the Np(IV) state found within the parent spent nuclear fuel [1]. In the immediate vicinity of the spent fuel's surface the redox and nucleation behavior is likely to promote

Preliminary sensitivity analyses of corrosion models for BWIP [Basalt Waste Isolation Project] container materials

International Nuclear Information System (INIS)

Anantatmula, R.P.

1984-01-01

A preliminary sensitivity analysis was performed for the corrosion models developed for Basalt Waste Isolation Project container materials. The models describe corrosion behavior of the candidate container materials (low carbon steel and Fe9Cr1Mo), in various environments that are expected in the vicinity of the waste package, by separate equations. The present sensitivity analysis yields an uncertainty in total uniform corrosion on the basis of assumed uncertainties in the parameters comprising the corrosion equations. Based on the sample scenario and the preliminary corrosion models, the uncertainty in total uniform corrosion of low carbon steel and Fe9Cr1Mo for the 1000 yr containment period are 20% and 15%, respectively. For containment periods ≥ 1000 yr, the uncertainty in corrosion during the post-closure aqueous periods controls the uncertainty in total uniform corrosion for both low carbon steel and Fe9Cr1Mo. The key parameters controlling the corrosion behavior of candidate container materials are temperature, radiation, groundwater species, etc. Tests are planned in the Basalt Waste Isolation Project containment materials test program to determine in detail the sensitivity of corrosion to these parameters. We also plan to expand the sensitivity analysis to include sensitivity coefficients and other parameters in future studies. 6 refs., 3 figs., 9 tabs

Influence of silica nanospheres on corrosion behavior of magnesium matrix syntactic foam

Science.gov (United States)

Qureshi, W.; Kannan, S.; Vincent, S.; Eddine, N. N.; Muhammed, A.; Gupta, M.; Karthikeyan, R.; Badari, V.

2018-04-01

Over the years, the development of Magnesium alloys as biodegradable implants has seen significant advancements. Magnesium based materials tend to provide numerous advantages in the field of biomedical implants over existing materials such as titanium or stainless steel. The present research focuses on corrosive behavior of Magnesium reinforced with different volume percentages of Hollow Silica Nano Spheres (HSNS). These behaviors were tested in two different simulated body fluids (SBF) namely, Hank’s Buffered Saline Solution (HBSS) and Phosphate Buffered Solution (PBS). This corrosion study was done using the method of electrochemical polarization with a three-electrode configuration. Comparative studies were established by testing pure Mg which provided critical information on the effects of the reinforcing material. The HSNS reinforced Mg displayed desirable characteristics after corrosion experiments; increased corrosion resistance was witnessed with higher volume percentage of HSNS.

Corrosion behavior of stainless steel weldments in physiological solutions

Science.gov (United States)

Farooq, A.; Azam, M.; Deen, K. M.

2018-01-01

In this study corrosion behavior of TIG welded 316L stainless steel plates in simulated biological solutions is investigated. The mechanical testing results showed slight decrease in ductility after welding and the fracture surface represented mixed cleavage and inclusions containing dimple structure. The heat affected and weld zone (WZ) demonstrated higher corrosion potential and relatively large pitting tendency than base metal (BM) in both Hank’s and Ringer’s solution. The formation of delta (δ) ferrite in the heat affected and WZ decreased the corrosion resistance as confirmed from potentiodynamic Tafel scans. The decrease in pitting resistance and lower protection tendency of the WZ compared to BM and heat affected zone was also quantified from the cyclic polarization trends.

Electrochemical corrosion behavior of A 516 steel using corrosive environments with varying concentrations of sodium thiosulphate

International Nuclear Information System (INIS)

Karim, F.; Arif, M.; Reza, I.; Akram, M.; Hussain, N.; Ali, L.

2012-01-01

The corrosion behavior of A 516 steel was studied by potentiodynamic polarization technique. Environment used for these tests was sodium chloride (5%), acetic acid (0.5%) and sodium thiosulphate with varying concentration from 0.001 M to 1 M. Surface study was also carried out using optical microscope. The potentiodynamic polarization results revealed the formation of large number of pits in the sample, which was tested in the solution containing NaCl. Pitting corrosion study of alloy A516 G-70 was also conducted to see the effect of different concentrations of thiosulfate with or without addition of NaCl and acetic acid at room temperature. It was observed that different thiosulfate concentrations did not produce any difference in the polarization behavior of the alloys, when added in 5% NaCl and 0.5% acetic acid solution. However, in the absence of NaCl and acetic acid, thiosulfate concentration 0.001 mol/l or higher did produce general corrosion and pitting in the alloy at room temperature is shown.(Orig./A.B.)

An Investigation on Corrosion Behavior of a Multi-layer Modified Aluminum Brazing Sheet

Directory of Open Access Journals (Sweden)

Liu Wei

2016-01-01

Full Text Available The corrosion behavior of a multi-layer modified aluminum brazing sheet (AA4045/3003Mod./AA7072/AA4045 was investigated. The results shows that, the existence of BDP, which forms at the interface between clad and core layer during brazing, changes the corrosion form of the air side of the material from inter-granular corrosion to local exfoliation corrosion. The addition of anti-corrosion layer makes the corrosion form of the water side from inter-granular corrosion into uniform exfoliation corrosion. Compared to the normal triple-layer brazing sheet at the same thickness, the time to perforation of the modified four-layer brazing sheet is increased by more than 200%.

Investigation of corrosion behavior of aluminum flakes coated by polymeric nanolayer: Effect of polymer type

International Nuclear Information System (INIS)

Amirshaqaqi, Naghmeh; Salami-Kalajahi, Mehdi; Mahdavian, Mohammad

2014-01-01

Highlights: • Protection of aluminum pigments from corrosion phenomenon by an encapsulating polystyrene and poly(acrylic acid) nanolayers. • Chemical stability of the aluminum pigments in alkaline and acidic aqueous media was examined. • Polystyrene coating remarkably improved flakes’ anticorrosion property while PAA evolved hydrogen. - Abstract: Protection of aluminum pigments from corrosion phenomenon has been extended by an encapsulating polystyrene (PS) and poly(acrylic acid) (PAA) nanolayers. Flakes were first coupled with 3-methacryloxypropyltrimethoxysilane (MPS) and in situ polymerizations of styrene and acrylic acid, initiating with Azobisisobutyronitrile (AIBN) were performed. The encapsulated flakes were characterized by Fourier transform infrared (FTIR), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscope (TEM). Also, polymer chains were analyzed by gel permeation chromatography (GPC). Subsequently the chemical stability of the pigments in alkaline and acidic aqueous media was examined. Results indicated that polystyrene coating remarkably improved flakes’ anticorrosion property while PAA evolved hydrogen

Corrosion behavior of alloy 800H (Fe-21Cr-32Ni) in supercritical water

International Nuclear Information System (INIS)

Tan, L.; Allen, T.R.; Yang, Y.

2011-01-01

Research highlights: → Testing conditions and sample microstructures showed effects on corrosion behaviors. → EBSD and FIB/TEM were used to characterize microstructure in addition to SEM/EDS and XRD. → The formation mechanism of mushroom-shaped oxidation is proposed. → Oxidation thermodynamics and kinetics predict and interpret the corrosion behaviors. - Abstract: The effect of testing conditions (temperature, time, and oxygen content) and material's microstructure (the as-received and the grain boundary engineered conditions) on the corrosion behavior of alloy 800H in high-temperature pressurized water was studied using a variety of characterization techniques. Oxidation was observed as the primary corrosion behavior on the samples. Oxide exfoliation was significantly mitigated on the grain boundary engineered samples compared to the as-received ones. The oxide formation, including some 'mushroom-shaped oxidation', is predicted via a combination of thermodynamics and kinetics influenced by the preferential diffusion of specific species using short-cut diffusion paths.

Effect of Electrolyte Composition on Corrosion Behavior of PEO Treated AZ91 Mg Alloy

International Nuclear Information System (INIS)

Park, Kyeong Jin; Lee, Jae Ho

2009-01-01

Mg and Mg alloys have been used for lots of applications, including automobile industry, aerospace, mobile phone and computer parts owing to low density. However, Mg and Mg alloys have a restricted application because of poor corrosion properties. Thus, improved surface treatments are required to produce protective films that protect the substrate from corrosion environments. Environmental friendly Plasma Electrolytic Oxidation (PEO) has been widely investigated on magnesium alloys. PEO process combines electrochemical oxidation with plasma treatment in the aqueous solution. In this study, AZ91 Mg alloys were treated by PEO process in controlling the current with PC condition and treated time, concentration of NaF, NaOH, and Na 2 SiO 3 . The surface morphology and phase composition were analyzed using SEM, EDS and XRD. The potentiodynamic polarization tests were carried out for the analysis of corrosion properties of specimen. Additionally, salt spray tests were carried out to examine and compare the corrosion properties of the PEO treated Mg alloys

Corrosion Behavior of Low-C Medium-Mn Steel in Simulated Marine Immersion and Splash Zone Environment

Science.gov (United States)

Zhang, Dazheng; Gao, Xiuhua; Su, Guanqiao; Du, Linxiu; Liu, Zhenguang; Hu, Jun

2017-05-01

The corrosion behavior of low-C medium-Mn steel in simulated marine immersion and splash zone environment was studied by static immersion corrosion experiment and wet-dry cyclic corrosion experiment, respectively. Corrosion rate, corrosion products, surface morphology, cross-sectional morphology, elemental distribution, potentiodynamic polarization curves and electrochemical impedance spectra were used to elucidate the corrosion behavior of low-C medium-Mn steel. The results show that corrosion rate in immersion zone is much less than that in splash zone owing to its relatively mild environment. Manganese compounds are detected in the corrosion products and only appeared in splash zone environment, which can deteriorate the protective effect of rust layer. With the extension of exposure time, corrosion products are gradually transformed into dense and thick corrosion rust from the loose and porous one in these two environments. But in splash zone environment, alloying elements of Mn appear significant enrichment in the rust layer, which decrease the corrosion resistance of the steel.

Evaluation of nitrogen containing reducing agents for the corrosion control of materials relevant to nuclear reactors

Energy Technology Data Exchange (ETDEWEB)

Kumar, Padma S. [Water and Steam Chemistry Division, BARC Facilities, Kalpakkam, Tamilnadu (India); Mohan, D. [Department of Chemistry, Anna University, Chennai, Tamilnadu (India); Chandran, Sinu; Rajesh, Puspalata; Rangarajan, S. [Water and Steam Chemistry Division, BARC Facilities, Kalpakkam, Tamilnadu (India); Velmurugan, S., E-mail: svelu@igcar.gov.in [Water and Steam Chemistry Division, BARC Facilities, Kalpakkam, Tamilnadu (India)

2017-02-01

Materials undergo enhanced corrosion in the presence of oxidants in aqueous media. Usually, hydrogen gas or water soluble reducing agents are used for inhibiting corrosion. In the present study, the feasibility of using alternate reducing agents such as hydrazine, aqueous ammonia, and hydroxylamine that can stay in the liquid phase was investigated. A comparative study of corrosion behavior of the structural materials of the nuclear reactor viz. carbon steel (CS), stainless steel (SS-304 LN), monel-400 and incoloy-800 in the oxidizing and reducing conditions was also made. In nuclear industry, the presence of radiation field adds to the corrosion problems. The radiolysis products of water such as oxygen and hydrogen peroxide create an oxidizing environment that enhances the corrosion. Electrochemical studies at 90 °C showed that the reducing agents investigated were efficient in controlling corrosion processes in the presence of oxygen and hydrogen peroxide. Evaluation of thermal stability of hydrazine and its effect on corrosion potential of SS-304 LN were also investigated in the temperature range of 200–280 °C. The results showed that the thermal decomposition of hydrazine followed a first order kinetics. Besides, a change in electrochemical corrosion potential (ECP) was observed from −0.4 V (Vs SHE) to −0.67 V (Vs SHE) on addition of 5 ppm of hydrazine at 240 °C. Investigations were also made to understand the distribution behavior of hydrogen peroxide and hydrazine in water-steam phases and it was found that both the phases showed identical behavior. - Highlights: • Hydrazine was found to be a promising reducing agent for oxidant control. • In presence of hydrazine corrosion potential of SS304 LN was well below −230 mV. • SS304LN could be protected from IGSCC by hydrazine addition. • Thermal and radiation stability of hydrazine at 285 °C was found satisfactory.

Electrochemical corrosion behavior of Ni-containing hypoeutectic Al-Si alloy

Directory of Open Access Journals (Sweden)

Abul Hossain

2015-12-01

Full Text Available Electrochemical corrosion characteristics of the thermally treated 2 wt % Ni-containing Al-6Si-0.5Mg alloy were studied in NaCl solutions. The corrosion behavior of thermally treated (T6 Al-6Si-0.5Mg (-2Ni alloys in 0.1 M NaCl solution was investigated by electrochemical potentiodynamic polarization technique consisting of linear polarization method using the fit of Tafel plot and electrochemical impedance spectroscopy (EIS techniques. Generally, linear polarization experiments revealed a decrease of the corrosion rate at thermal treated Al-6Si-0.5Mg-2Ni alloy. The EIS test results showed that there is no significant change in charge transfer resistance (Rct after addition of Ni to Al-6Si-0.5Mg alloy. The magnitude of the positive shift in the open circuit potential (OCP, corrosion potential (Ecorr and pitting corrosion potential (Epit increased with the addition of Ni to Al-6Si-0.5Mg alloy. The forms of corrosion in the studied Al-6Si-0.5Mg alloy (except Al-6Si-0.5Mg-2Ni alloy are pitting corrosion as obtained from the scanning electron microscopy (SEM study.

Suppressing hydrogen ingress during aqueous corrosion of CANDU Zr-2.5 Nb pressure tube material

International Nuclear Information System (INIS)

Elmoselhi, M.B.; Donner, A.; Brennenstuhl, A.; Warr, B.D.; Ellis, P.J.; Evans, D.W.

2002-01-01

As a result of their special properties, including low neutron cross-section and intrinsic corrosion resistance, Zr alloys are used in the fabrication of nuclear core components, particularly fuel cladding (in most reactor types) and also Zr-2.5 Nb pressure tubes in CANDU trademark (Canada Deuterium Uranium) reactors. Corrosion and H uptake during service can limit the life of these components. Therefore, remedial action may be appropriate to slow the H uptake rate and prolong the working life of these reactor components. This work has explored the possibility of reducing H uptake in pressure tube material by incorporating an inhibiting agent into the corrosion environment. Two approaches have been tested, depositing a thin metallic film on the initial oxide surface and adding an inhibiting agent to the solution. The latter approach appears more practical. Screening experiments were conducted in short-term (∝30 day) exposures in high temperature (340 C) aqueous out-reactor environments, simulating the CANDU trademark heat transport coolant with various chemistries. Compounds tested included aluminum acetate, aluminum nitrate, lithium nitrate, rhodium nitrate and yttrium nitrate. Comparison of results from the aluminum nitrate additives and aluminum acetate additives suggests that the nitrate anion is the effective ingredient for H ingress inhibition. The nitrate anion appears to reduce the rate of H ingress regardless of the associated cation. However, each cation appears to affect the rate of corrosion differently. These cations were found to be incorporated in the oxide film. (authors)

Study on metal material corrosion behavior of packaging of cement solidified form

International Nuclear Information System (INIS)

He Zhouguo; Lin Meiqiong; Fan Xianhua

1997-01-01

The corrosion behavior of A3 carbon steel is studied by the specimens that are exposed to atmosphere, embedded in cement solidified form or immersed in corrosion liquid. The corrosion rate is determined by mass change of the specimens. In order to compare the corrosion resistant performance of various coatings, the specimens painted with various material such as epoxide resin, propionic acid resin, propane ether resin and Ti-white paint are tested. The results of the tests show that corrosion rate of A3 carbon steel is less than 10 -3 mm·a -1 in the atmosphere and the cement solidified from, less than 0.1 mm·a -1 in the corrosion liquids, and pH value in the corrosion liquids also affect the corrosion rate of A3 carbon steel. The corrosion resistant performance of Ti-white paint is better than that of other paints. So, A3 carbon steel as packaging material can meet the requirements during storage

Corrosion behavior of austempered ductile iron (ADI) in iron ore slurry

African Journals Online (AJOL)

Corrosion behavior of austempered ductile iron (ADI) in iron ore slurry was studied as a function of the microstructure developed by austempering at 380 and 300°C for different exposure time in the slurry. The corrosion rates of the ADI balls immersed in the iron ore slurry was determined using weight loss method.

Corrosion behavior of oxide dispersion strengthened ferritic steels in supercritical water

Energy Technology Data Exchange (ETDEWEB)

Gao, Wenhua [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Shanghai 200240 (China); Guo, Xianglong, E-mail: guoxianglong@sjtu.edu.cn [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Shanghai 200240 (China); Shen, Zhao [Department of Materials Science, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Zhang, Lefu, E-mail: lfzhang@sjtu.edu.cn [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Shanghai 200240 (China)

2017-04-01

The corrosion resistance of three different Cr content oxide dispersion strengthened (ODS) ferritic steels in supercritical water (SCW) and their passive films formed on the surface have been investigated. The results show that the dissolved oxygen (DO) and chemical composition have significant influence on the corrosion behavior of the ODS ferritic steels. In 2000 ppb DO SCW at 650 °C, the 14Cr-4Al ODS steel forms a tri-layer oxide film and the surface morphologies have experienced four structures. For the tri-layer oxide film, the middle layer is mainly Fe-Cr spinel and the Al is gradually enriched in the inner layer. - Highlights: • We evaluated the corrosion resistance of three different Cr content ODS steels at 650 °C in supercritical water. • Corrosion behavior of ODS steels is rarely reported and ODS steel may be promising material for generation IV reactors. • We found total opposite phenomenon compared to Lee's work before. Our result may be more reasonable.

Surface Modification of Zinc with an Oxime for Corrosion Protection in Chloride Medium

Directory of Open Access Journals (Sweden)

Ganesha Achary

2013-01-01

Full Text Available The surface treatment of zinc was done with different concentrations of an oxime (2E-2-(hydroxylamino-1,2-diphenylethanol molecule by the immersion method. The electrochemical corrosion studies of surface-treated zinc specimens were performed in aqueous sodium chloride solution (1 M, pH 5.0 at different temperatures in order to study the corrosion mechanism. The recorded electrochemical data indicated a basic modification of the cathodic corrosion behavior of the treated zinc resulting in a decrease of the electron transfer rate. The zinc samples treated by immersion in the inhibiting organic solution presented good corrosion resistance. Using scanning electron microscopy (SEM, it was found that a protective film was formed on the surface of zinc.

Study on the corrosion assessment of overpack welds-II (Joint research)

International Nuclear Information System (INIS)

Mitsui, Hiroyuki; Otsuki, Akiyoshi; Asano, Hidekazu; Taniguchi, Naoki; Kawakami, Susumu; Yui, Mikazu

2006-06-01

The corrosion resistance at the overpack welds is possible to be inferior to that at base metal, so that it has been concerned that a short-term failure of overpack may occur due to the corrosion penetration at the welds. In this study, corrosion mechanisms specific to the welds were extracted for carbon steel which is one of the candidate materials for overpacks. And then the corrosion experiments for welded carbon steel were planed to evaluate long-term integrity of overpack welds. Based on this plan, electrochemical tests for welded carbon steel using the samples welded by EBW and TIG were carried out, and the corrosion behavior of welded zone was compared with that of base metal. The results of anodic polarization tests in 0.01M and 0.1M carbonate aqueous solutions for base metal, heat affected zone and welded metal showed that; As for EBW, the anodic polarization curves were not affected by welding although the metallurgical structures vary with base metal, heat affected zone and welded metal. As for TIG, the current density of welded metal was larger than that of base metal and of heat affected zone, and local dissolution with immediate in current density was observed in 0.01M-pH10 carbonate aqueous solution. As shown in these results, it is expected that the corrosion resistance at the welds by EBW will be equal to that at base metal. As for TIG, however, it was indicated that the corrosion resistance is possible to be lower than base metal. (author)

Corrosion Behavior of Steels in Supercritical CO₂ for Power Cycle Applications

Energy Technology Data Exchange (ETDEWEB)

Repukaiti, Richard [National Energy Technology Lab. (NETL), Albany, OR (United States); Oregon State Univ., Corvallis, OR (United States); Teeter, Lucas [National Energy Technology Lab. (NETL), Albany, OR (United States); Oregon State Univ., Corvallis, OR (United States); Ziomek-Moroz, Margaret [National Energy Technology Lab. (NETL), Albany, OR (United States); Dogan, Omer [National Energy Technology Lab. (NETL), Albany, OR (United States); Tucker, Julie [Oregon State Univ., Corvallis, OR (United States)

2017-07-07

In order to understand issues with corrosion of heat exchanger materials in direct supercritical carbon dioxide (sCO₂) power cycles, a series of autoclave exposure experiments and electrochemical experiments have been conducted. Corrosion behaviors of 347H stainless steel and P91 martensitic-ferrtic steel in sCO₂ environment have been compared. In autoclave exposure tests performed at 50°C- 245°C and 80 bar. Mass change measurements, surface characterization, and corrosion product analysis have been conducted to understand the corrosion behavior of steels in sCO₂ containing H₂O and O₂. Electrochemical tests performed at room temperature and 50°C, a simulation environment of water condensation phase with dissolved CO₂ was prepared to evaluate the corrosion resistance of materials. From both types of experiments, generally 347H showed higher corrosion resistance than P91.

Stress corrosion cracking of uranium--niobium alloys

International Nuclear Information System (INIS)

Magnani, N.J.

1978-03-01

The stress corrosion cracking behavior of U-2 1 / 4 , 4 1 / 2 , 6 and 8 wt % Nb alloys was evaluated in laboratory air and in aqueous Cl - solutions. Thresholds for crack propagation were obtained in these environments. The data showed that Cl - solutions are more deleterious than air environments. Tests were also conducted in pure gases to identify the species in the air responsible for cracking. These data showed the primary stress corrodent is water vapor for the most reactive alloy, U-2 1 / 4 % Nb, while O 2 is primarily responsible for cracking in the more corrosion resistant alloys, U-6 and 8% Nb. The 4 1 / 2 % alloy was found to be susceptible in both H 2 O and O 2 environments

Mechanisms of Copper Corrosion in Aqueous Environments. A report from the Swedish National Council for Nuclear Waste's scientific workshop, on November 16, 2009

Energy Technology Data Exchange (ETDEWEB)

2010-07-01

In 2010 the Swedish Nuclear Fuel and Waste Management Company, SKB, plans to submit its license application for the final repository of spent nuclear fuel. The proposed method is the so-called KBS-3 method and implies placing the spent nuclear fuel in copper canisters, surrounded by a buffer of bentonite clay, at 500 m depth in the bedrock. The site selected by SKB to host the repository is located in the municipality of Oesthammar on the Swedish east coast. The copper canister plays a key role in the design of the repository for spent nuclear fuel in Sweden. The long-term physical and chemical stability of copper in aqueous environments is fundamental for the safety evolution of the proposed disposal concept. However, the corrosion resistance of copper has been questioned by results obtained under anoxic conditions in aqueous solution. These observations caused some head-lines in the Swedish newspapers as well as public and political concerns. Consequently, the Swedish National Council for Nuclear Waste organized a scientific workshop on the issue 'Mechanisms of Copper Corrosion in Aqueous Environments'. The purpose of the workshop was to address the fundamental understanding of the corrosion characteristics of copper regarding oxygen-free environments, and to identify what additional information is needed to assess the validity of the proposed corrosion mechanism and its implication on the containment of spent nuclear fuel in a copper canister. This seminar report is based on the presentations and discussions at the workshop. It also includes written statements by the members of the expert panel

Effects of Alloyed Carbon on the General Corrosion and the Pitting Corrosion Behavior of FeCrMnN Stainless Steels

Energy Technology Data Exchange (ETDEWEB)

Ha, Heon-Young; Lee, Tae-Ho; Kim, Sung-Joon [Korea Institute of Materials Science, Changwon (Korea, Republic of)

2011-10-15

The effects of alloyed carbon on the pitting corrosion, the general corrosion, and the passivity behavior of Fe{sub 1}8Cr{sub 1}0Mn{sub 0}.4Nx{sub C} (x=0 ⁓ 0.38 wt%) alloys were investigated by various electrochemical methods and XPS analysis. The alloyed carbon increased the general corrosion resistance of the FeCrMnN matrix. Carbon enhanced the corrosion potential, reduced the metal dissolution rate, and accelerated the hydrogen evolution reaction rate in various acidic solutions. In addition, carbon promoted the pitting corrosion resistance of the matrix in a chloride solution. The alloyed carbon in the matrix increased the chromium content in the passive film, and thus the passive film became more protective.

Corrosion behavior of duplex and reference cladding in NPP Grohnde

International Nuclear Information System (INIS)

Besch, O.A.; Yagnik, S.K.; Eucken, C.M.; Bradley, E.R.

1996-01-01

The Nuclear Fuel Industry Research (NFIR) Group undertook a lead test assembly (LTA) program in NPP Grohnde PWR in Germany to assess the corrosion performance of duplex and reference cladding. Two identical 16 by 16 LTAs, each containing 32 peripheral test rods, completed four reactor cycles, reaching a peak rod burnup of 46 MWd/kgU. The results from poolside examinations performed at the end of each cycle, together with power histories and coolant chemistry, are reported. Five different cladding materials were characterized during fabrication. The corrosion performance of the cladding materials was tracked in long-term tests in high-pressure, high-temperature autoclaves. The relative ranking of corrosion behavior in such tests corresponded well with the in-reactor corrosion performance. The extent and distribution of hydriding in duplex and reference specimens during the autoclave testing has been characterized. The in-reactor corrosion data indicate that the low-tin Zircaloy-4 reference cladding, R2, had an improved corrosion resistance compared to high-tin Zircaloy-4 reference cladding, R1. Two types of duplex cladding, D1 (Zr-2.5% Nb) and D2 (Zr-0.4% Fe-0.5% Sn), showed an even further improvement in corrosion resistance compared to R2 cladding. The third duplex cladding, D3 (Zr-4 + 1.0% Nb), had significantly less corrosion resistance, which was inferior to R1. The in-reactor and out-reactor corrosion performances have been ranked

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

Atmospheric Corrosion Behavior of 2A12 Aluminum Alloy in a Tropical Marine Environment

Directory of Open Access Journals (Sweden)

Zhongyu Cui

2015-01-01

Full Text Available Atmospheric corrosion behavior of 2A12 aluminum alloy exposed to a tropical marine environment for 4 years was investigated. Weight loss of 2A12 alloy in the log-log coordinates can be well fitted with two linear segments, attributing to the evolution of the corrosion products. EIS results indicate that the corrosion product layer formed on the specimens exposed for 12 months or longer presents a good barrier effect. Corrosion morphology changes from pitting corrosion to severe intergranular corrosion with the extension of exposure time, resulting in the reduction of the mechanical properties.

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.)

The effect of urea on the corrosion behavior of different dental alloys.

Science.gov (United States)

Geckili, Onur; Bilhan, Hakan; Bilgin, Tayfun; Anthony von Fraunhofer, J

2012-01-01

Intraoral corrosion of dental alloys has biological, functional, and esthetic consequences. Since it is well known that the salivary urea concentrations undergo changes with various diseases, the present study was undertaken to determine the effect of salivary urea concentrations on the corrosion behavior of commonly used dental casting alloys. Three casting alloys were subjected to polarization scans in synthetic saliva with three different urea concentrations. Cyclic polarization clearly showed that urea levels above 20 mg/100 ml decreased corrosion current densities, increased the corrosion potentials and, at much higher urea levels, the breakdown potentials. The data indicate that elevated urea levels reduced the corrosion susceptibility of all alloys, possibly through adsorption of organics onto the metal surface. This study indicates that corrosion testing performed in sterile saline or synthetic saliva without organic components could be misleading.

Corrosion behavior of Zircaloy 4 cladding material. Evaluation of the hydriding effect

International Nuclear Information System (INIS)

Blat, M.

1997-04-01

In this work, particular attention has been paid to the hydriding effect in PIE and laboratory test to validate a detrimental hydrogen contribution on Zircaloy 4 corrosion behavior at high burnup. Laboratory corrosion tests results confirm that hydrides have a detrimental role on corrosion kinetics. This effect is particularly significant for cathodic charged samples with a massive hydride outer layer before corrosion test. PIE show that at high burnup a hydride layer is formed underneath the metal/oxide interface. The results of the metallurgical examinations are discussed with respect to the possible mechanisms involved in this detrimental effect of hydrogen. Therefore, according to the laboratory tests results and PIE, hydrogen could be a strong contributor to explain the increase in corrosion rate at high burnup. (author)

An electrochemical investigation of the corrosion behavior of aluminum alloys in chloride containing solutions

International Nuclear Information System (INIS)

Campos Filho, Jorge Eustaquio de

2005-01-01

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)

Structural characteristics and corrosion behavior of biodegradable Mg-Zn, Mg-Zn-Gd alloys.

Science.gov (United States)

Kubásek, J; Vojtěch, D

2013-07-01

In this research, binary Mg-Zn (up to 3 wt% Zn) and ternary Mg-Zn-Gd (up to 3 wt% Gd, 3 wt% Zn) alloys were prepared by induction melting in an argon atmosphere. The structures of these alloys were characterized using light and scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction and X-ray fluorescence. In addition, Brinell hardness measurements were taken to supplement these studies. Corrosion behavior was evaluated by immersion tests and potentiodynamic measurements in a physiological solution (9 g/l NaCl). Depending on the composition, structures of the as-cast alloys contained α-Mg dendrites, MgZn, Mg5Gd and Mg3Gd2Zn3 phases. Compared to pure Mg, zinc improved the corrosion resistance of binary Mg-Zn. Gadolinium also improved the corrosion resistance in the case of Mg-1Zn-3Gd alloy. The highest corrosion rate was observed for Mg-3Zn-3Gd alloy. Our results improve the understanding of the relationships between the structure and corrosion behavior of our studied alloy systems.

Tannin bark Melalauca cajuputi powell (gelam) as green corrosion inhibitor of mild steel

Energy Technology Data Exchange (ETDEWEB)

Talib, Nur Atiqah Abu; Zakaria, Sarani; Hua, Chia Chin; Othman, Norinsan Kamil [School of Applied Physic, Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

2014-09-03

Tannin was extracted from gelam bark and used to produce corrosion inhibitor for mild steel. Tannin was extracted from gelam bark using 70% aqueous acetone for 6 hour. Tannin powder was characterization using fourier transform infrared spectroscopy to analyse chemical component in tannin and Scanning electron microscope (SEM) for tannin physical structure. The tannin effect on the corrosion inhibition of mild steel has been investigated in 1Mol HCl solution for 6 hour followed ASTM. The weight loss method were applied to study the mild steel corrosion behavior in the present and absend of different concentration of tannin (250, 300, 350)ppm. Tannin act good inhibitor as corrosion inhibitor for mild steel in acid medium. Surface morphology of carbon steel with and without inhibitor was investigated by scanning electron microscopy.

Corrosion behaviour of sensitized and unsensitized Alloy 900 (UNS 1.4462) in concentrated aqueous lithium bromide solutions at different temperatures

International Nuclear Information System (INIS)

Leiva-Garcia, R.; Munoz-Portero, M.J.; Garcia-Anton, J.

2010-01-01

Duplex stainless steels can undergo microstructural changes if they are heated improperly. When that happens, duplex stainless steels are sensitized and intermetallic phases appear. The high Chromium and Molybdenum content promotes the formation of secondary phases as a consequence of the heat treatment. These secondary phases, which are rich in alloying elements, such as Cr and Mo, deplete these elements from the neighbouring phases, leading to a reduction in corrosion resistance. In order to study the influence of the secondary phases on the corrosion parameters, samples of duplex stainless steel, Alloy 900 (UNS 1.4462), have been heated in argon atmosphere at 825 deg. C for 1 h. The corrosion behaviour of sensitized and unsensitized Alloy 900 has been analyzed in a concentrated aqueous lithium bromide (LiBr) solution of 992 g/L by means of cyclic potentiodynamic curves. Secondary phase presence reduces the pitting potential value of Alloy 900. Besides, the pitting potential decreases with temperature. On the other hand, the corrosion potential and open circuit potential values increase with temperature and sensitization.

Cathodic corrosion: Part 2. Properties of nanoparticles synthesized by cathodic corrosion

International Nuclear Information System (INIS)

Yanson, A.I.; Yanson, Yu.I.

2013-01-01

We demonstrate how cathodic corrosion in concentrated aqueous solutions enables one to prepare nanoparticles of various metals and metal alloys. Using various characterization methods we show that the composition of nanoparticles remains that of the starting material, and the resulting size distribution remains rather narrow. For the case of platinum we show how the size and possibly even the shape of the nanoparticles can be easily controlled by the parameters of corrosion. Finally, we discuss the advantages of using the nanoparticles prepared by cathodic corrosion for applications in (electro-)catalysis.

Corrosion behavior of stainless steel and zirconium in nitric acid containing highly oxidizing species

International Nuclear Information System (INIS)

Mayuzumi, Masami; Fujita, Tomonari

1994-01-01

Corrosion behavior of 304ELC, 310Nb stainless steels and Zirconium was investigated in the simulated dissolver solution of a reprocessing plant to obtain fundamental data for life prediction. Corrosion of heat transfer surface was also investigated in nitric acid solutions containing Ce ion. The results obtained are as follows: (1) Stainless steels showed intergranular corrosion in the simulated dissolver solution. The corrosion rate increased with time and reached to a constant value after several hundred hours of immersing time. The constant corrosion rate changed depending on potential suggesting that corrosion potential dominates the corrosion process. 310Nb showed superior corrosion resistance to 304ELC. (2) Corrosion rate of stainless steels increased in the heat transfer condition. The causes of corrosion enhancement are estimated to be higher corrosion potential and higher temperature of heat transfer surface. (3) Zirconium showed perfect passivity in all the test conditions employed. (author)

Effects of copper and titanium on the corrosion behavior of newly fabricated nanocrystalline aluminum in natural seawater

International Nuclear Information System (INIS)

Sherif, El-Sayed M.; Ammar, Hany Rizk; Khalil, Khalil Abdelrazek

2014-01-01

Graphical abstract: - Highlights: • We fabricated nanocrystalline Al and some of its alloys by mechanical alloying method. • The corrosion behavior of the fabricated materials in natural seawater was reported. • We found that Al suffers both uniform and localized corrosion in the seawater. • The presence of Cu significantly decreased the corrosion of Al. • The addition of Ti to the Al–Cu alloy presented more protection to Al against corrosion. - Abstract: Fabrication of a newly nanocrystalline Al and two of its alloys, namely Al–10%Cu; and Al–10%Cu–5%Ti has been carried out using mechanical alloying (MA) technique. The corrosion behavior of these materials in aerated stagnant Arabian Gulf seawater (AGSW) at room temperature has been reported. Cyclic potentiodynamic polarization (CPP), chronoamperometric current-time (CCT) and electrochemical impedance spectroscopy (EIS) measurements along with scanning electron microscopy (SEM) and X-ray energy dispersive (EDX) investigations were employed to report the corrosion behavior of the fabricated materials. All results indicated that Al suffers both uniform and localized corrosion in the AGSW test solution. The presence of 10%Cu decreases the corrosion current density, the anodic and cathodic currents and corrosion rate and increases the corrosion resistance of Al. The addition of 5%Ti to the Al–10%Cu alloy produced further decreases in the corrosion parameters. Measurements together confirmed that the corrosion of the fabricated materials in AGSW decreases in the order Al > Al–10%Cu > Al–10%Cu–5%Ti

Effects of copper and titanium on the corrosion behavior of newly fabricated nanocrystalline aluminum in natural seawater

Energy Technology Data Exchange (ETDEWEB)

Sherif, El-Sayed M., E-mail: esherif@ksu.edu.sa [Mechanical Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Al-Riyadh 11421 (Saudi Arabia); Electrochemistry and Corrosion Laboratory, Department of Physical Chemistry, National Research Centre , (NRC), Dokki, 12622, Cairo 8 (Egypt); Ammar, Hany Rizk [Metallurgical and Materials Engineering Department, Faculty of Petroleum and Mining Engineering, Suez University, Suez (Egypt); Khalil, Khalil Abdelrazek [Metallurgical and Materials Engineering Department, Faculty of Petroleum and Mining Engineering, Suez University, Suez (Egypt); Mechanical Design and Materials Department, Faculty of Energy Engineering, Aswan University, Aswan (Egypt)

2014-05-01

Graphical abstract: - Highlights: • We fabricated nanocrystalline Al and some of its alloys by mechanical alloying method. • The corrosion behavior of the fabricated materials in natural seawater was reported. • We found that Al suffers both uniform and localized corrosion in the seawater. • The presence of Cu significantly decreased the corrosion of Al. • The addition of Ti to the Al–Cu alloy presented more protection to Al against corrosion. - Abstract: Fabrication of a newly nanocrystalline Al and two of its alloys, namely Al–10%Cu; and Al–10%Cu–5%Ti has been carried out using mechanical alloying (MA) technique. The corrosion behavior of these materials in aerated stagnant Arabian Gulf seawater (AGSW) at room temperature has been reported. Cyclic potentiodynamic polarization (CPP), chronoamperometric current-time (CCT) and electrochemical impedance spectroscopy (EIS) measurements along with scanning electron microscopy (SEM) and X-ray energy dispersive (EDX) investigations were employed to report the corrosion behavior of the fabricated materials. All results indicated that Al suffers both uniform and localized corrosion in the AGSW test solution. The presence of 10%Cu decreases the corrosion current density, the anodic and cathodic currents and corrosion rate and increases the corrosion resistance of Al. The addition of 5%Ti to the Al–10%Cu alloy produced further decreases in the corrosion parameters. Measurements together confirmed that the corrosion of the fabricated materials in AGSW decreases in the order Al > Al–10%Cu > Al–10%Cu–5%Ti.

Corrosion inhibitors for neutral aqueous media based on the products on sugar cane processing. 1.Furfural derivatives as inhibitors

International Nuclear Information System (INIS)

Ledovskikh, V.M.; Kamekho Khinnebra, Kh.Kh.

1993-01-01

A series of carboxy-, nitrogen- and nitroderivaties of furfural - the main product of sugar cane processing (furancasboxylic acid, 5-nitrofurancarboxylic acid and its salts, furfurine, furfurylamine) was studied as inhibitors of iron and copper, corrosion in aqueous-salt media. Nitrofuroates of sodium and ammonium, which decelerate anode process, intensity cathode one and provide the stable passive state, are considered to be the most effective

Evaluation of the corrosion of aluminum tubes under conditions of natural imersion in aqueous medium

International Nuclear Information System (INIS)

Oliveira, M.F. de

1985-01-01

This work evaluates the corrosion of aluminum tubes under conditions of natural immersion in aqueous medium. Local attack was observed on the surface of the tubes for all temperatures studied. It was found that the mass flucturation of the samples tested in deionized water at room temperatures is practically inexistent. However, at temperatures of 45 and 60 0 C the aluminum react rapidly with water forming a film of hydrated oxide of aluminum known as bayerite. It was verified that the contact of graphite and particles containing high content of Cu with aluminum forms a galvanic couple which should be avoided. (Author) [pt

Modelling and Optimization of Corrosion Inhibition of Mild Steel in Phosphoric Acid by Red Pomegranate Peels Aqueous Extract

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Khalid Hamid Rashid

2011-11-01

Full Text Available Taguchi experimental design (TED is applied to find the optimum effectiveness of aqueous Red Pomegranate Peel (RPP extract as a green inhibitor for the corrosion of mild steel in 2M H3PO4 solution. The Taguchi methodology has been used to study the effects of changing, temperature, RPP concentration and contact period, at three levels. Weight-loss measurements were designed by construction a L9 orthogonal arrangement of experiments. Results of the efficiencies of inhibition were embraced for the signal to noise proportion & investigation of variance (ANOVA. The results were further processed with a MINITAB-17 software package to find the optimal conditions for inhibitor usage. Second order polynomial model was used for experimental data fitting. Optimum conditions for achieving the maximum corrosion inhibition efficiency are obtained from optimizing the above model and are found as follow: 39.66 °C temperature of acidic media, 38.29 ml/L inhibitor concentration and 2.95 h contact period. Results demonstrated that rate of corrosion was increased with temperature increasing & decreasing inhibitor concentration. It was concluded that the Taguchi design was adequately useful in the optimization of operating parameters and that RPP sufficiently inhibited the corrosion of steel at the range of variables studied.

Electrochemical migration, whisker formation, and corrosion behavior of printed circuit board under wet H2S environment

International Nuclear Information System (INIS)

Zou, Shiwen; Li, Xiaogang; Dong, Chaofang; Ding, Kangkang; Xiao, Kui

2013-01-01

Highlights: •The electrochemical migration, whisker formation, and corrosion behavior of PCB under wet H 2 S environment were observed and studied systematically. •The process of electrochemical migration of solder joints is explained. •The corrosion mechanism of PCB interconnectors induced by micro pores under wet H 2 S environment is discussed, and the corrosion reaction model is proposed. -- Abstract: Electrochemical migration, whisker formation, and corrosion behavior of printed circuit board (PCB) under wet H 2 S environment were analyzed by environment scanning electron microscope (ESEM), Energy dispersive X-ray spectroscopy (EDS) with mapping and element phase cluster (EPC) techniques, Raman Spectrum analysis and electrochemical impedance spectroscopy (EIS) technology. The results showed that nonuniform corrosion behavior occurred on PCB surfaces under 1 ppm wet H 2 S at 40 °C; whiskers formed on the inner sidewall of via-holes with a growth rate of 1.2 Å/s; numerous corrosion products migrated through the pore of plated gold layer, which broke off the protective layer. The corrosion rate was accelerated according to the big-cathode-small-anode model

Regularities of transition of steel corrosion products into aqueous medium

International Nuclear Information System (INIS)

Nikitin, V.I.; Gvozd', A.M.; Karpova, T.Ya.

1981-01-01

Effect of different factors on a degree of steel corrosion product transition to a water medium has been studied. Ratio of a specific masm qsub(c) of the corrosion products transferring to the water and a specific masm q of all the steel corrosion products produced under the given conditions was used as a criterium characterizing a degree of corrosion product transition from steel surfaces to water. The transition degree to water at a high temperature of different kind steel corrosion products differs relatively few (qsub(c)/q=0.5-0.7) in the water containing oxygen and different salts on increasing temperature, the corrosion process is characterized with continuous decrease of a relative amount of the corrosion products transferring to the medium. On the contrary, in the deaerated water the transition degree of perlite steel corrosion products to water remains constant in a wide temperature range (100-320 deg C). Besides chromium, nickel being a part of austenitic steel composition affects positively decrease of the transition degree of the corrosion products to water as well as q and qsub(c) reduction. The most difference in corrosion characteristics and the transition degree to water is observed when affecting colant steels in the low-temperature zone of the steam generator [ru

Mechanical and corrosion behaviors of developed copper-based metal matrix composites

Science.gov (United States)

Singh, Manvandra Kumar; Gautam, Rakesh Kumar; Prakash, Rajiv; Ji, Gopal

2018-03-01

This work investigates mechanical properties and corrosion resistances of cast copper-tungsten carbide (WC) metal matrix composites (MMCs). Copper matrix composites have been developed by stir casting technique. Different sizes of micro and nano particles of WC particles are utilized as reinforcement to prepare two copper-based composites, however, nano size of WC particles are prepared by high-energy ball milling. XRD (X-rays diffraction) characterize the materials for involvement of different phases. The mechanical behavior of composites has been studied by Vickers hardness test and compression test; while the corrosion behavior of developed composites is investigated by electrochemical impedance spectroscopy in 0.5 M H2SO4 solutions. The results show that hardness, compressive strength and corrosion resistance of copper matrix composites are very high in comparison to that of copper matrix, which attributed to the microstructural changes occurred during composite formation. SEM (Scanning electron microscopy) reveals the morphology of the corroded surfaces.

Effect of Sulfur and Chlorine on Fireside Corrosion Behavior of Inconel 740 H Superalloy

Science.gov (United States)

Jin-tao, Lu; Yan, Li; Zhen, Yang; Jin-yang, Huang; Ming, Zhu; Gu, Y.

2018-03-01

Fireside corrosion behavior of Inconel 740H superalloy was studied at 750 °C in simulated coal ash/flue gas environments by means of XRD, SEM and EDS. The results indicated that the corrosion behavior was strongly related to the SO2 levels and was significantly affected by NaCl additions. In presence of the atmospheres with 0.1 % SO2, the alloy exhibited the highest corrosion resistance due to formation of a stable and dense Cr2O3 film. In presence of the atmosphere with 1.5 % SO2, however, a non-coherent and porous Cr2O3 film was formed. The thickness of film and internal sulfides were substantially increased. The NaCl additions significantly accelerated the corrosion process. A non-protective outer oxide film was formed, composed by multiple layers with serious inner sulfide and spallation. The depths of internal oxidizing and sulfuration zones were significantly increased. The mechanism of ash corrosion formation was also discussed.

Correlation between zirconium oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys

International Nuclear Information System (INIS)

Park, Sang Yoon; Lee, Myung Ho; Choi, Byoung Kwon; Jeong, Yong Hwan; Jung, Youn Ho

2001-01-01

To evaluate the correlation of Zr oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys, the corrosion behavior of the alloys was tested in the autoclave containing 70 ppm LiOH solution at 360 .deg. C. The characteristics of the oxide on the alloys were investigated by using the electrochemical impedance spectrosocpy (EIS) method. The corrosion resistance of the alloys was evaluated from the corrosion rate determined as a function of the concentration of Nb. The equivalent circuit of the oxide was composed on the base of the spectrum from EIS measurements on the oxide layers that had formed at pre-and post-transition regions on the curve of corrosion rate. By using the capacitance characteristics of the equivalent circuit, the thickness of impervious layer, it's electrical resistance and characteristics of space charge layer were evaluated. The corrosion characteristics of the Zr-Nb-Sn-Fe-Cu alloys were successfully explained by applying the EIS test results

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

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.

Comparison of Corrosion Behavior of Electrochemically Deposited Nano-Cobalt-Coated Ni Sheet

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Nasser Al-Aqeeli

2013-01-01

Full Text Available Corrosion behavior of nano-coblat-coated Ni sheet was compared with pure Ni and 20% Fe-Ni alloy sheet using potentiodynamic polarization and linear polarization technique in 0.1 M NaCl solution at room temperature. Results showed that corrosion resistance properties of nano-Co-coated Ni sheet were almost same as that of pure Ni sheet, however corrosion resistance of 20% Fe-Ni sheet was decreased significantly. Pitting potential of 20% Fe-Ni sheet was subsequently decreased as compared to pure Ni sheet as well as nano-cobalt-coated Ni sheet. SEM/EDS analysis of the corroded surfaces showed that both pure Ni and nano-coblat-coated Ni sheet did not show any appreciable corrosion however significant corrosion was observed in the case of 20% Fe-Ni sheet.

Critique of the Ford-Andresen film rupture model for aqueous stress corrosion cracking

International Nuclear Information System (INIS)

Hall, M.M.

2009-01-01

The Ford-Andresen film rupture model for aqueous stress corrosion cracking has obtained a prominent position in the nuclear reactor industry. The model is said to have superior predictive capabilities because it is derived from a fundamental understanding of the film rupture-repassivation mechanism of crack advance. However, a critical review shows that there are conceptual and mathematical problems with the Ford-Andresen model development; there are inconsistencies among the stated and implied assumptions, the crack tip current density expression lacks the necessary dependence on crack tip strain rate and the fundamental proportionality that exists between crack tip strain rate and crack growth rate is overlooked and omitted from the model development. Consequently, the Ford-Andresen model must be considered neither phenomenologically nor fundamentally supported.

Evaluation of corrosive behavior of SAE 5155 by corrosion environment

International Nuclear Information System (INIS)

An, Jae Pil; Park, Keyung Dong

2005-01-01

In this study, the influence of shot peening and corrosive condition for corrosion property was investigated on immersed in 3.5% NaCl, 10% HNO 3 + 3% HF, 6% FeCl 3 . The immersion test was performed on two kinds of specimen. The immersion periods was performed 30days. Corrosion potential, weight loss were investigated from experimental results. From test results, the effect of shot peening on the corrosion was evaluated

Effect of calcium on the microstructure and corrosion behavior of microarc oxidized Mg-xCa alloys.

Science.gov (United States)

Pan, Yaokun; Chen, Chuanzhong; Feng, Rui; Cui, Hongwei; Gong, Benkui; Zheng, Tingting; Ji, Yarou

2018-01-16

Magnesium alloys are potential biodegradable implants for biomedical applications, and calcium (Ca) is one kind of ideal element being examined for magnesium alloys and biodegradable ceramic coatings owing to its biocompatibility and mechanical suitability. In this study, microarc oxidation (MAO) coatings were prepared on Mg-xCa alloys to study the effect of Ca on the microstructure and corrosion resistance of Mg-xCa alloys and their surface MAO coatings. The electrochemical corrosion behavior was investigated using an electrochemical workstation, and the degradability and bioactivity were evaluated by soaking tests in simulated body fluid (SBF) solutions. The corrosion products were characterized by scanning electron microscopy, x-ray diffractometry, and Fourier transform infrared spectrometry. The effects of Ca on the alloy phase composition, microstructure, MAO coating formation mechanism, and corrosion behavior were investigated. Results showed that the Mg-0.82Ca alloy and MAO-coated Mg-0.82Ca exhibited the highest corrosion resistance. The number and distribution of Mg 2 Ca phases can be controlled by adjusting the Ca content in the Mg-xCa alloys. The proper amount of Ca in magnesium alloy was about 0.5-0.8 wt. %. The pore size, surface roughness, and corrosion behavior of microarc oxidized Mg-xCa samples can be controlled by the number and distribution of the Mg 2 Ca phase. The corrosion behaviors of microarc oxidized Mg-Ca in SBF solutions were discussed.

Review on stress corrosion and corrosion fatigue failure of centrifugal compressor impeller

Science.gov (United States)

Sun, Jiao; Chen, Songying; Qu, Yanpeng; Li, Jianfeng

2015-03-01

Corrosion failure, especially stress corrosion cracking and corrosion fatigue, is the main cause of centrifugal compressor impeller failure. And it is concealed and destructive. This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments, and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution (AD), the hydrogen-induced cracking (HIC), and the combined AD and HIC mechanisms. The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking. The effects of stress ratio, loading frequency, and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized. The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments, which contain sulfide, chlorides, and carbonate, are analyzed. The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments. The current research methods for centrifugal compressor impeller corrosion failure are analyzed. Physical analysis, numerical simulation, and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.

Influence of Freeze-Thaw Damage on the Steel Corrosion and Bond-Slip Behavior in the Reinforced Concrete

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Fangzhi Zhu

2016-01-01

Full Text Available This paper mainly studies the behavior of steel corrosion in various reinforced concrete under freeze-thaw environment. The influence of thickness of concrete cover is also discussed. Additionally, the bond-slip behavior of the reinforced concrete after suffering the freeze-thaw damage and steel corrosion has also be presented. The results show that the freeze-thaw damage aggravates the steel corrosion in concrete, and the results become more obvious in the concrete after suffering serious freeze-thaw damage. Compared with the ordinary concrete, both air entrained concrete and waterproofing concrete possess better resistance to steel corrosion under the same freeze-thaw environment. Moreover, increasing the thicknesses of concrete cover is also an effective method of improving the resistance to steel corrosion. The bond-slip behavior of reinforced concrete with corroded steel decreases with the increase of freeze-thaw damage, especially for the concrete that suffered high freeze-thaw cycles. Moreover, there exists a good correlation between the parameters of bond-slip and freeze-thaw cycles. The steel corrosion and bond-slip behavior of reinforced concrete should be considered serious under freeze-thaw cycles environment, which significantly impact the durability and safety of concrete structure.

The effects of Nitinol phases on corrosion and fatigue behavior

Science.gov (United States)

Denton, Melissa

The purpose of these studies was to provide a detailed understanding of Nitinol phases and their effects on corrosion and fatigue life. The two primary phases, austenite and martensite, were carefully evaluated with respect to material geometry, corrosion behavior, wear, and fatigue life. Material characterization was performed using several techniques that include metallography, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), x-ray photoelectron spectrum (XPS), and Auger electron spectroscopy (AES). Uniaxial tensile tests were conducted to determine the mechanical properties such as elongation, ultimate tensile strength, modulus, transformation strain, and plateau stress. In addition, accelerated wear testing and four point bend fatigue testing were completed to study the fatigue life and durability of the material. The corrosion of Nitinol was found to be dependent on various surface conditions. Electrochemical corrosion behavior of each phase was investigated using cyclic potentiodyamic polarization testing. The corrosion response of electropolished Nitinol was found to be acceptable, even after durability testing. Stress-induced martensite had a lower breakdown potential due to a rougher surface morphology, while thermally induced martensite and austenite performed similarly well. The surface conditioning also had a significant effect on Nitinol mechanical properties. Electropolishing provided a smooth mirror finish that reduced localized texture and enhanced the ductility of the material. Quasi-static mechanical properties can be good indicators of fatigue life, but further fatigue testing revealed that phase transformations had an important role as well. The governing mechanisms for the fatigue life of Nitinol were determined to be both martesitic phase transformations and surface defects. A new ultimate dislocation strain model was proposed based on specific accelerated step-strain testing.

Effects of Fe and Cr on corrosion behavior of ZrFeCr alloys in 500 oC steam

International Nuclear Information System (INIS)

Wang Jun; Fan Hongyuan; Xiong Ji; Liu Hong; Miao Zhi; Ying Shihao; Yang Gang

2011-01-01

Research highlights: Amount and size of SPP will effect the corrosion resistance of Zr alloy at 500 o C/10.3 MPa. - Abstract: A study of the corrosion behaviors of ZrFeCr alloy and the influence of microstructure on corrosion resistance are described by X-ray diffraction and scanning electron microscope in this paper. The results show that several ZrFeCr alloys exhibit protective behavior throughout the test and oxide growth is stable and protective. The best alloy has the composition Zr1.0Fe0.6Cr. Fitting of the weight gain curves for the protective oxide alloys in the region of protective behavior, it showed nearly cubic behavior for the most protective alloys. The Zr1.0Fe0.6Cr has the more laves Zr(Fe,Cr) 2 precipitate in matrix and it has the better corrosion resistance. The Zr0.2Fe0.1Cr has little precipitate, the biggest hydrogen absorption and the worst corrosion resistance. The number of precipitates and the amount of hydrogen absorption in Zr alloy plays an important role on corrosion resistance behaviors in 500 o C/10.3 MPa steam.

Corrosion testing and prediction in SCWO environments

International Nuclear Information System (INIS)

Kriksunov, L.B.; Macdonald, D.D.

1995-01-01

The authors review recent advances in corrosion monitoring and modeling in SCWO systems. Techniques and results of experimental corrosion measurements at high temperatures are presented. Results of modeling corrosion in high subcritical and supercritical aqueous systems indicate the primary importance of density of water in corrosion processes. A phenomenological model has been developed to simulate corrosion processes at nearcritical and supercritical temperatures in SCWO systems. They discuss as well the construction of Pourbaix diagrams for metals in SCW

Microgalvanic Corrosion Behavior of Cu-Ag Active Braze Alloys Investigated with SKPFM

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Armen Kvryan

2016-04-01

Full Text Available The nature of microgalvanic couple driven corrosion of brazed joints was investigated. 316L stainless steel samples were joined using Cu-Ag-Ti and Cu-Ag-In-Ti braze alloys. Phase and elemental composition across each braze and parent metal interface was characterized and scanning Kelvin probe force microscopy (SKPFM was used to map the Volta potential differences. Co-localization of SKPFM with Energy Dispersive Spectroscopy (EDS measurements enabled spatially resolved correlation of potential differences with composition and subsequent galvanic corrosion behavior. Following exposure to the aggressive solution, corrosion damage morphology was characterized to determine the mode of attack and likely initiation areas. When exposed to 0.6 M NaCl, corrosion occurred at the braze-316L interface preceded by preferential dissolution of the Cu-rich phase within the braze alloy. Braze corrosion was driven by galvanic couples between the braze alloys and stainless steel as well as between different phases within the braze microstructure. Microgalvanic corrosion between phases of the braze alloys was investigated via SKPFM to determine how corrosion of the brazed joints developed.

Structure and Corrosion Behavior of Arc-Sprayed Zn-Al Coatings on Ductile Iron Substrate

Science.gov (United States)

Bonabi, Salar Fatoureh; Ashrafizadeh, Fakhreddin; Sanati, Alireza; Nahvi, Saied Mehran

2018-02-01

In this research, four coatings including pure zinc, pure aluminum, a double-layered coating of zinc and aluminum, and a coating produced by simultaneous deposition of zinc and aluminum were deposited on a cast iron substrate using electric arc-spraying technique. The coatings were characterized by XRD, SEM and EDS map and spot analyses. Adhesion strength of the coatings was evaluated by three-point bending tests, where double-layered coating indicated the lowest bending angle among the specimens, with detection of cracks at the coating-substrate interface. Coatings produced by simultaneous deposition of zinc and aluminum possessed a relatively uniform distribution of both metals. In order to evaluate the corrosion behavior of the coatings, cyclic polarization and salt spray tests were conducted. Accordingly, pure aluminum coating showed susceptibility to pitting corrosion and other coatings underwent uniform corrosion. For double-layered coating, SEM micrographs revealed zinc corrosion products as flaky particles in the pores formed by pitting on the surface, an indication of penetration of corrosion products from the lower layer (zinc) to the top layer (aluminum). All coatings experienced higher negative corrosion potentials than the iron substrate, indicative of their sacrificial behavior.

Investigation of models to predict the corrosion of steels in flowing liquid lead alloys

International Nuclear Information System (INIS)

Balbaud-Celerier, F.; Barbier, F.

2001-01-01

Corrosion of steels exposed to flowing liquid lead alloys can be affected by hydrodynamic parameters. The rotating cylinder system is of interest for the practical evaluation of the fluid velocity effect on corrosion and for the prediction of the corrosion behavior in other geometries. Models developed in aqueous medium are tested in the case of liquid metal environments. It is shown that equations established for the rotating cylinder and the pipe flow geometry can be used effectively in liquid lead alloys (Pb-17Li) assuming the corrosion process is mass transfer controlled and the diffusion coefficient of dissolved species is known. The corrosion rate of martensitic steels in Pb-17Li is shown to be independent of the geometry when plotted as a function of the mass transfer coefficient. Predictions about the corrosion of steel in liquid Pb-Bi are performed but experiments are needed to validate the results obtained by modeling

Corrosion resistance and protection mechanism of hot-dip Zn-Al-Mg alloy coated steel sheet under accelerated corrosion environment; Yoyu Zn-Al-Mg kei gokin mekki koban no sokushin fushoku kankyoka ni okeru taishokusei toi boshoku kiko

Energy Technology Data Exchange (ETDEWEB)

Komatsu, A.; Izutani, H.; Tsujimura, T.; Ando, A.; Kittaka, T. [NKK Corp., Tokyo (Japan)

2000-08-01

Corrosion behavior of hot-dip Zn-6%Al 0-3%Mg alloy coated steel sheets in cyclic corrosion test (CCT) has been investigated. The corrosion resistance was improved with increasing Mg content in the coating layer, and the highest corrosion resistance was observed at 3% Mg. In Zn-6%Al-3%Mg alloy coated steel sheet, the formations of zinc carbonate hydroxide and zinc oxide were suppressed for longer duration compared with Zn-0.2%Al and Zn-4.5%Al-0.l%Mg alloy coated steel sheets. As a result, zinc chloride hydroxide existed stable on the surface of the coating layer. From the polarization behaviors in 5% NaCl aqueous solution after CCT, it was found that the corrosion current density of Zn-6%At-3%Mg alloy coated steel sheet was much smaller than those of Zn-0.2%Al and Zn-4.5%Al-0.1%Mg alloy coated steel sheets. As zinc carbonate hydroxide and zinc oxide had poor adhesion to the coating layer and had porous structures, these corrosion products were considered to have little protective action for the coating layer. Therefore, it was concluded that Mg suppressed the formation of such nonprotective corrosion products. resulting in the remarkable improvement of corrosion resistance. (author)

Microstructure and corrosion behavior of laser processed NiTi alloy.

Science.gov (United States)

Marattukalam, Jithin J; Singh, Amit Kumar; Datta, Susmit; Das, Mitun; Balla, Vamsi Krishna; Bontha, Srikanth; Kalpathy, Sreeram K

2015-12-01

Laser Engineered Net Shaping (LENS™), a commercially available additive manufacturing technology, has been used to fabricate dense equiatomic NiTi alloy components. The primary aim of this work is to study the effect of laser power and scan speed on microstructure, phase constituents, hardness and corrosion behavior of laser processed NiTi alloy. The results showed retention of large amount of high-temperature austenite phase at room temperature due to high cooling rates associated with laser processing. The high amount of austenite in these samples increased the hardness. The grain size and corrosion resistance were found to increase with laser power. The surface energy of NiTi alloy, calculated using contact angles, decreased from 61 mN/m to 56 mN/m with increase in laser energy density from 20 J/mm(2) to 80 J/mm(2). The decrease in surface energy shifted the corrosion potentials to nobler direction and decreased the corrosion current. Under present experimental conditions the laser power found to have strong influence on microstructure, phase constituents and corrosion resistance of NiTi alloy. Copyright © 2015 Elsevier B.V. All rights reserved.

Study on the hot corrosion behavior of a cast Ni-base superalloy

Energy Technology Data Exchange (ETDEWEB)

Wang, W.; Guo, J.T.; Zhang, J.; Yuan, C.; Zhou, L.Z.; Hu, Z.Q. [Chinese Academy of Sciences, Shenyang (China). Inst. of Metal Research

2010-07-01

Hot corrosion behavior of Nickel-base cast superalloy K447 in 90% Na{sub 2}SO{sub 4} + 10% NaCl melting salt at 850 C and 900 C was studied. The hot corrosion kinetic of the alloy follows parabolic rate law under the experimental conditions. The external layer is mainly Cr{sub 2}O{sub 3} scale which is protective to the alloy, the intermediate layer is the Ti-rich phase, and the internal layer is mainly the international oxides and sulfides. With increased corrosion time and temperature, the oxide scales are gradually dissolved in the molten salt and then precipitate as a thick and non-protective scale. Chlorides cause the formation of volatile species, which makes the oxide scale disintegrate and break off. The corrosion kinetics and morphology examinations tend to support the basic dissolution model for hot corrosion mechanisms. (orig.)

Corrosion behavior of niobium coated 304 stainless steel in acid solution

Energy Technology Data Exchange (ETDEWEB)

Pan, T.J., E-mail: tjpan@cczu.edu.cn [School of Material Science and Engineering, Jiangsu Collaborative Innovation Center for Photovolatic Science and Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory of Material Surface Technology, Changzhou 213164 (China); Chen, Y.; Zhang, B. [School of Material Science and Engineering, Jiangsu Collaborative Innovation Center for Photovolatic Science and Engineering, Changzhou University, Changzhou 213164 (China); Hu, J. [School of Material Science and Engineering, Jiangsu Collaborative Innovation Center for Photovolatic Science and Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory of Material Surface Technology, Changzhou 213164 (China); Li, C. [Light Industry College of Liaoning University, Shenyang 110036 (China)

2016-04-30

Highlights: • The Nb coating produced by HEMAA offers good protection for 304SS in acid solution. • The coating increases corrosion potential and induces decrease of corrosion rate. • The protection of coating is ascribed to the stability of Nb in acid solution. - Abstract: The niobium coating is fabricated on the surface of AISI Type 304 stainless steel (304SS) by using a high energy micro arc alloying technique in order to improvecorrosion resistance of the steel against acidic environments. The electrochemical corrosion resistance of the niobium coating in 0.7 M sulfuric acid solutions is evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization and the open circuit potential versus time. Electrochemical measurements indicate that the niobium coating increases the free corrosion potential of the substrate by 110 mV and a reduction in the corrosion rate by two orders of magnitude compared to the substrate alone. The niobium coating maintains large impedance and effectively offers good protection for the substrate during the long-term exposure tests, which is mainly ascribed to the niobium coating acting inhibiting permeation of corrosive species. Finally, the corresponding electrochemical impedance models are proposed to elucidate the corrosion resistance behavior of the niobium coating in acid solutions.

Corrosion behavior of niobium coated 304 stainless steel in acid solution

International Nuclear Information System (INIS)

Pan, T.J.; Chen, Y.; Zhang, B.; Hu, J.; Li, C.

2016-01-01

Highlights: • The Nb coating produced by HEMAA offers good protection for 304SS in acid solution. • The coating increases corrosion potential and induces decrease of corrosion rate. • The protection of coating is ascribed to the stability of Nb in acid solution. - Abstract: The niobium coating is fabricated on the surface of AISI Type 304 stainless steel (304SS) by using a high energy micro arc alloying technique in order to improvecorrosion resistance of the steel against acidic environments. The electrochemical corrosion resistance of the niobium coating in 0.7 M sulfuric acid solutions is evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization and the open circuit potential versus time. Electrochemical measurements indicate that the niobium coating increases the free corrosion potential of the substrate by 110 mV and a reduction in the corrosion rate by two orders of magnitude compared to the substrate alone. The niobium coating maintains large impedance and effectively offers good protection for the substrate during the long-term exposure tests, which is mainly ascribed to the niobium coating acting inhibiting permeation of corrosive species. Finally, the corresponding electrochemical impedance models are proposed to elucidate the corrosion resistance behavior of the niobium coating in acid solutions.

Corrosion behavior of corrosion resistant alloys in stimulation acids

Energy Technology Data Exchange (ETDEWEB)

Cheldi, Tiziana [ENI E and P Division, 20097 San Donato Milanese Milano (Italy); Piccolo, Eugenio Lo; Scoppio, Lucrezia [Centro Sviluppo Materiali, via Castel Romano 100, 00128 Rome (Italy)

2004-07-01

In the oil and gas industry, selection of CRAs for downhole tubulars is generally based on resistance to corrosive species in the production environment containing CO{sub 2}, H{sub 2}S, chloride and in some case elemental sulphur. However, there are non-production environments to which these materials must also be resistant for either short term or prolonged duration; these environments include stimulation acids, brine and completion fluids. This paper reports the main results of a laboratory study performed to evaluate the corrosion and stress corrosion behaviour to the acidizing treatments of the most used CRAs for production tubing and casing. Laboratory tests were performed to simulate both 'active' and 'spent' acids operative phases, selecting various environmental conditions. The selected steel pipes were a low alloyed steel, martensitic, super-martensitic, duplex 22 Cr, superduplex 25 Cr and super-austenitic stainless steels (25 Cr 35 Ni). Results obtained in the 'active' acid environments over the temperature range of 100-140 deg. C, showed that the blend acids with HCl at high concentration and HCl + HF represented too much severe conditions, where preventing high general corrosion and heavy localised corrosion by inhibition package becomes very difficult, especially for duplex steel pipe, where, in some case, the specimens were completely dissolved into the solution. On the contrary, all steels pipes were successfully protected by inhibitor when organic acid solution (HCOOH + CH{sub 3}COOH) were used. Furthermore, different effectiveness on corrosion protection was showed by the tested inhibitors packages: e.g. in the 90% HCl at 12% + 10 CH{sub 3}COOH acid blend. In 'spent' acid environments, all steel pipes showed to be less susceptible to the localised and general corrosion attack. Moreover, no Sulphide Stress Corrosion Cracking (SSC) was observed. Only one super-austenitic stainless steel U-bend specimen showed

Corrosion behavior of aluminum-alumina composites in aerated 3.5 percent chloride solution

Science.gov (United States)

Acevedo Hurtado, Paul Omar

Aluminum based metal matrix composites are finding many applications in engineering. Of these Al-Al2O3 composites appear to have promise in a number of defense applications because of their mechanical properties. However, their corrosion behavior remains suspect, especially in marine environments. While efforts are being made to improve the corrosion resistance of Al-Al2O3 composites, the mechanism of corrosion is not well known. In this study, the corrosion behavior of powder metallurgy processed Al-Cu alloy reinforced with 10, 15, 20 and 25 vol. % Al2O3 particles (XT 1129, XT 2009, XT 2048, XT 2031) was evaluated in aerated 3.5% NaCl solution using microstructural and electrochemical measurements. AA1100-O and AA2024T4 monolithic alloys were also studied for comparison purposes. The composites and unreinforced alloys were subjected to potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) testing. Addition of 25 vol. % Al2O 3 to the base alloys was found to increase its corrosion resistance considerably. Microstructural studies revealed the presence of intermetallic Al2Cu particles in these composites that appeared to play an important role in the observations. Pitting potential for these composites was near corrosion potential values, and repassivation potential was below the corresponding corrosion potential, indicating that these materials begin to corrode spontaneously as soon as they come in contact with the 3.5 % NaCl solution. EIS measurements indicate the occurrence of adsorption/diffusion phenomena at the interface of the composites which ultimately initiate localized or pitting corrosion. Polarization resistance values were extracted from the EIS data for all the materials tested. Electrically equivalent circuits are proposed to describe and substantiate the corrosive processes occurring in these Al-Al2O 3 composite materials.

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.

Comparison of corrosion behavior between fusion cladded and explosive cladded Inconel 625/plain carbon steel bimetal plates

International Nuclear Information System (INIS)

Zareie Rajani, H.R.; Akbari Mousavi, S.A.A.; Madani Sani, F.

2013-01-01

Highlights: ► Both explosive and fusion cladding aggravate the corrosion resistance of Inconel 625. ► Fusion cladding is more detrimental to nonuniform corrosion resistance. ► Single-layered fusion coat does not show any repassivation ability. ► Adding more layers enhance the corrosion resistance of fusion cladding Inconel 625. ► High impact energy spoils the corrosion resistance of explosive cladding Inconel 625. -- Abstract: One of the main concerns in cladding Inconel 625 superalloy on desired substrates is deterioration of corrosion resistance due to cladding process. The present study aims to compare the effect of fusion cladding and explosive cladding procedures on corrosion behavior of Inconel 625 cladding on plain carbon steel as substrate. Also, an attempt has been made to investigate the role of load ratio and numbers of fusion layers in corrosion behavior of explosive and fusion cladding Inconel 625 respectively. In all cases, the cyclic polarization as an electrochemical method has been applied to assess the corrosion behavior. According to the obtained results, both cladding methods aggravate the corrosion resistance of Inconel 625. However, the fusion cladding process is more detrimental to nonuniform corrosion resistance, where the chemical nonuniformity of fusion cladding superalloy issuing from microsegregation, development of secondary phases and contamination of clad through dilution hinders formation of a stable passive layer. Moreover, it is observed that adding more fusion layers can enhance the nonuniform corrosion resistance of fusion cladding Inconel 625, though this resistance still remains weaker than explosive cladding superalloy. Also, the results indicate that raising the impact energy in explosive cladding procedure drops the corrosion resistance of Inconel 625.

The effect of recrystallization on corrosion and electrochemical behavior of 7150 Al alloy

Energy Technology Data Exchange (ETDEWEB)

Peng, G.S.; Chen, K.H.; Fang, H.C.; Chen, S.Y.; Chao, H. [State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

2011-01-15

By weight loss, potentiodynamic polarization, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) techniques complemented by optical and scanning electron microscopy observations, the effect of recrystallization on the corrosion, and electrochemical behavior of 7150 Al alloy was studied. The results indicated that the high recrystallization fraction 7150-1 was worse than the low recrystallization fraction 7150-2 on corrosion resistance. The analysis of EIS indicated that 7150-1 exhibited obvious pitting corrosion at 5 h immersion time, whereas 7150-2 showed no obvious pitting corrosion even at 33 h. The corrosion route developed along the grain boundary of recrystallization grains, not along the grain boundary of unrecrystallization grains. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Effect of free Cr content on corrosion behavior of 3Cr steels in a CO2 environment

Science.gov (United States)

Li, Wei; Xu, Lining; Qiao, Lijie; Li, Jinxu

2017-12-01

The corrosion behavior of 3Cr steels with three microstructures (martensite, bainite, combined ferrite and pearlite) in simulated oil field formation water with a CO2 partial pressure of 0.8 MPa was investigated. The relationships between Cr concentrations in corrosion scales and corrosion rates were studied. The precipitated phases that contained Cr were observed in steels of different microstructures, and free Cr content levels were compared. The results showed that steel with the martensite microstructure had the highest free Cr content, and thus had the highest corrosion resistance. The free Cr content of bainite steel was lower than that of martensite steel, and the corrosion rate of bainite steel was higher than that of martensite steel. Because large masses of Cr were combined in ferrite and pearlite steel, the corrosion rates of ferrite and pearlite steel were the highest. Free Cr content in steel affects its corrosion behavior greatly.

Characterization and corrosion behavior of ceramic coating on magnesium by micro-arc oxidation

International Nuclear Information System (INIS)

Durdu, Salih; Aytac, Aylin; Usta, Metin

2011-01-01

Highlights: · The commercial pure magnesium was coated by micro-arc oxidation method. · The coating is composed of two layers, a porous outer layer and a dense inner layer. · A super corrosion resistance was achieved with MAO coatings. · Coating with Mg 2 SiO 4 is more resistant to corrosion than that containing Mg 3 (PO 4 ) 2 . - Abstract: In this study, the commercial pure magnesium was coated in different aqueous solutions of Na 2 SiO 3 and Na 3 PO 4 by the micro-arc oxidation method (MAO). Coating thickness, phase composition, surface and cross sectional morphology and corrosion resistance of coatings were analyzed by eddy current method, X-ray diffraction (XRD), scanning electron microscope (SEM) and tafel extrapolation method, respectively. The average thickness of the coatings ranged from 52 to 74 μm for sodium silicate solution and from 64 to 88 μm for sodium phosphate solution. The dominant phases on the coatings were detected as spinal Mg 2 SiO 4 (Forsterite) and MgO (Periclase) for sodium silicate solution and Mg 3 (PO 4 ) 2 (Farringtonite) and MgO (Periclase) for sodium phosphate solution. SEM images reveal that the coating is composed of two layers as of a porous outer layer and a dense inner layer. The corrosion results show the coating consisting Mg 2 SiO 4 is more resistant to corrosion than that containing Mg 3 (PO 4 ) 2 .

Long-term corrosion/oxidation studies under controlled humidity conditions

International Nuclear Information System (INIS)

Gdowski, G.

1997-01-01

Independent of thermal loading scenarios, the waste packages at the potential repository at Yucca Mountain, Nevada will be exposed to environmental conditions where there is the possibility of significant water film formation occurring on the waste packages. Water films can cause aggressive aqueous film electrochemical corrosion on susceptible metals or alloys. Water film formation will be facilitated when relative humidities are high, when hygroscopic salts are present on the surfaces, when corrosion products are hygroscopic, and when particles form crevices with the surfaces (capillary effect). Also certain gaseous contaminants, such as, NO x and SO 2 , can facilitate water film formation. It should be noted that water film formation can occur at isolated spots (e.g. surface defects and salt particles) and need not cover the entire surface for electrochemical corrosion to occur. This activity will characterize the long term corrosion of metal specimens at two nominal relative humidities (50 and 85%) and at 80 C. Under the low relative humidity (50%) condition, water film formation is expected to be limited and therefore aqueous film electrochemical corrosion is expected also to be limited. Under the high relative humidity (85%) condition, significant water film formation is expected to occur under some test conditions, and subsequently aqueous film electrochemical corrosion will occur on susceptible materials

Preliminary study on the corrosion behavior of carbon steel in Horonobe groundwater environment

International Nuclear Information System (INIS)

Taniguchi, Naoki; Kogawa, Noritaka; Maeda, Kazuto

2006-08-01

It is necessary to understand the corrosion behavior of candidate overpack materials to plan the in-situ engineered barrier test at underground laboratory constructing at Horonobe and to design the overpacks suitable to Horonobe environment. The preliminary corrosion tests of carbon steel which is a candidate material for overpacks were carried out using artificial groundwater and actual groundwater sampled at Horonobe. As the results of anodic polarization experiments, the anodic polarization curves of carbon steel in buffer material were active dissolution type, and the corrosion type of carbon steel in Horonobe groundwater environment was expected to be general corrosion. The results of immersion test under air equilibrium condition showed that the degrees of corrosion localization were not exceeded the data obtained in previous studies. The trend of corrosion rates in buffer material under anaerobic condition were similar to the data obtained in previous studies. Based on the experimental results, it was confirmed that the corrosion assessment model and assumed corrosion rate in second progress report (H12 report) can be applied to the assessment for Horonobe groundwater condition. (author)

Corrosion behavior of high purity Fe-Cr-Ni alloys in trans-passive condition

International Nuclear Information System (INIS)

Mayuzumi, Masami; Ohta, Jyoji; Kako, Kenji

1998-01-01

The corrosion behavior of high-purity (99.99%) Fe-Cr-Ni alloys was investigated in 13 N nitric acid with/without Ce 4+ ions to clarify the effect of impurities on the trans-passive corrosion of stainless steel. The following results were obtained. (1) Almost no intergranular corrosion was observed in the high-purity alloys, although the corrosion rate of the matrix region was nearly the same as that of a commercial stainless steel with the same Cr and Ni content. (2) Due to the improved intergranular corrosion resistance, the effect of the purification became significant in the corrosion condition with the grain-separation being predominant. (3) The high-purity alloys showed higher susceptivility to intergranular corrosion with aging treatment between 873 K and 1073 K. Although the sulfuric acid/copper sulfate test suggested the formation of Cr-depleted zones, a grain boundary micro-analysis using a FETEM with an EDX did not reveal any change in Cr content or impurity segregain along the grain boundaries. The mechanism of corrosion enhancement resulting from the aging treatment remains nuclear. (author)

Stress Corrosion Cracking Behavior of LD10 Aluminum Alloy in UDMH and N2O4 propellant

Science.gov (United States)

Zhang, Youhong; Chang, Xinlong; Liu, Wanlei

2018-03-01

The LD10 aluminum alloy double cantilever beam specimens were corroded under the conditions of Unsymmetric Uimethyl Hydrazine (UDMH), Dinitrogen Tetroxide (N2O4), and 3.5% NaCl environment. The crack propagation behavior of the aluminum alloy in different corrosion environment was analyzed. The stress corrosion cracking behavior of aluminum alloy in N2O4 is relatively slight and there are not evident stress corrosion phenomenons founded in UDMH.

Long term corrosion behavior of the WAK-HLW glass in salt solutions

International Nuclear Information System (INIS)

Luckscheiter, B.; Nesovic, M.

1998-01-01

The corrosion behavior of the HLW glass GP WAK1 containing simulated HLW oxides from the WAK reprocessing plant in Karlsruhe is investigated in long-term corrosion experiments at high S/V ratios in two reference brines at 110 and 190 C. In case of the MgCl 2 -rich solution the leachate becomes increasingly acid with reaction time up to a final pH of about 3.5 at 190 C. In the NaCl-rich solution the pH rises to about 8.5 after one year of reaction. The release of soluble elements in MgCl 2 solution, under Si-saturated conditions, is proportional to the surface area of the sample and the release increases at 190 C according to a t 1/2 rate law. This time dependence may be an indication of diffusion controlled matrix dissolution. However, at 110 C the release of the mobile elements cannot be described by a t 1/2 rate law as the time exponents are much lower than 0.5. This difference in corrosion behavior may be explained by the higher pH of about 5 at 110 C. In case of NaCl solution under alkaline conditions, the release of soluble elements is not proportional to the surface area of the sample and it increases with time exponents much lower than 0.5. After one year of reaction at 190 C a sharp increase of the release values of some elements was observed. This increase might be explained by the high pH of the solution attained after one year. The corrosion mechanism in NaCl solution, as well as in MgCl 2 solution at 110 C, has not yet been explained. By corrosion experiments in water at constant pH values between 2 and 10, it could be shown that the time exponents of the release of Li and B decrease with increasing pH of the solution. This result can explain qualitatively the differences found in the corrosion behavior of the glass under the various conditions

Corrosion resistance of CrN thin films produced by dc magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Ruden, A. [Laboratorio de Física del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 vía al Magdalena, Manizales (Colombia); Laboratorio de Recubrimientos Duros y Aplicaciones Industriales–RDAI, Universidad del Valle, Calle 13 N° 100-00 Ciudadela Meléndez, Cali (Colombia); Departamento de matemáticas, Universidad Tecnológica de Pereira, Pereira (Colombia); Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Laboratorio de Física del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 vía al Magdalena, Manizales (Colombia); Paladines, A.U.; Sequeda, F. [Laboratorio de Recubrimientos Duros y Aplicaciones Industriales–RDAI, Universidad del Valle, Calle 13 N° 100-00 Ciudadela Meléndez, Cali (Colombia)

2013-04-01

In this study, the electrochemical behavior of chromium nitride (CrN) coatings deposited on two steel substrates, AISI 304 and AISI 1440, was investigated. The CrN coatings were prepared using a reactive d.c. magnetron sputtering deposition technique at two different pressures (P1 = 0.4 Pa and P2 = 4 Pa) with a mixture of N{sub 2}–Ar (1.5-10). The microstructure and crystallinity of the CrN coatings were investigated using X-ray diffraction. The aqueous corrosion behavior of the coatings was evaluated using two methods. The polarization resistance (Tafel curves) and electrochemical impedance spectra (EIS) in a saline (3.5% NaCl solution) environment were measured in terms of the open-circuit potentials and polarization resistance (R{sub p}). The results indicated that the CrN coatings present better corrosion resistance and R{sub p} values than do the uncoated steel substrates, especially for the coatings produced on the AISI 304 substrates, which exhibited a strong enhancement in the corrosion resistance. Furthermore, better behavior was observed for the coatings produced at lower pressures (0.4 Pa) than those grown at 4 Pa.

Influence of Temperature on Corrosion Behavior of 2A02 Al Alloy in Marine Atmospheric Environments

Directory of Open Access Journals (Sweden)

Min Cao

2018-02-01

Full Text Available The corrosion behavior of 2A02 Al alloy under 4 mg/cm2 NaCl deposition at different temperatures (from 30 to 80 °C has been studied. This corrosion behavior was researched using mass-gain, scanning electron microscopy-SEM, laser scanning confocal microscopy-LSCM, X-ray photoelectron spectroscopy-XPS and other techniques. The results showed and revealed that the corrosion was maximal at 60 °C after 200 h of exposure. The increase of temperature not only affected the solubility of oxygen gas in the thin film, but also promoted the transport of ions (such as Cl−, and the formation of protective AlO(OH, which further affects the corrosion speed.

Influence of Temperature on Corrosion Behavior of 2A02 Al Alloy in Marine Atmospheric Environments

Science.gov (United States)

Cao, Min; Liu, Li; Fan, Lei; Yu, Zhongfen; Li, Ying; Oguzie, Emeka E.; Wang, Fuhui

2018-01-01

The corrosion behavior of 2A02 Al alloy under 4 mg/cm2 NaCl deposition at different temperatures (from 30 to 80 °C) has been studied. This corrosion behavior was researched using mass-gain, scanning electron microscopy-SEM, laser scanning confocal microscopy-LSCM, X-ray photoelectron spectroscopy-XPS and other techniques. The results showed and revealed that the corrosion was maximal at 60 °C after 200 h of exposure. The increase of temperature not only affected the solubility of oxygen gas in the thin film, but also promoted the transport of ions (such as Cl−), and the formation of protective AlO(OH), which further affects the corrosion speed. PMID:29401690

Corrosion Behavior of Welded Joints for Cargo Oil Tanks of Crude Oil Carrier

Institute of Scientific and Technical Information of China (English)

Jin-shan WEI; Yan-chang QI; Zhi-ling TIAN; Yun PENG

2016-01-01

E32 grade corrosion resistant steel was welded with welding wires with three different S contents.The mi-crostructure,mechanical properties,inclusions,and corrosion behavior of welded joint were investigated.The joint coupon corrosion test and potentiodynamic polarization test were carried out under the simulated corrosion environ-ment of the inner bottom plates of cargo oil tanks.The pitting initiation and propagation mechanism of the weld metal were studied by scanning electron microscopy and infinite focus.The results indicated that the microstructures of three kinds of weld metals are all composed of acicular ferrite,ferrite side-plate and proeutectoid ferrite.The micro-structure of heat-affected zone is composed predominantly of bainite.Joint welded with low S filler wire has good me-chanical properties.S can decrease free corrosion potential and increase the corrosion tendency.The pitting initiation is oxide inclusion or sulfide-oxide inclusion complex.S can induce the formation of occluded area and promote the corrosion propagation.The chemical compositions of weld metal is similar to base metal,which can limit the galvanic corrosion between weld metal and base metal,and avoid formation of corrosion step.

Effect of niobium element on the electrochemical corrosion behavior of depleted uranium

Energy Technology Data Exchange (ETDEWEB)

Wu, Yanping, E-mail: wuyanping-2@126.com; Wu, Quanwen; Zhu, Shengfa, E-mail: zhushf-306@163.com; Pu, Zhen; Zhang, Yanzhi; Wang, Qinguo; Lang, Dingmu; Zhang, Yuping

2016-09-15

Depleted uranium (DU) has many military and civilian uses. However, its high chemical reactivity limits its application. The effect of Nb content on corrosion behavior of DU is evaluated by scanning Kelvin probe and electrochemical corrosion measurements. The Volta potential value of DU and U-2.5 wt% Nb is about the same level, the Volta potential value of U-5.7 wt% Nb has a rise of 370mV{sub SHE} in comparison with DU. The polarization current of U-5.7 wt% Nb alloy is about an order of magnitude of that of DU. The Nb{sub 2}O{sub 5} is the protective layer for the U-Nb alloys. The negative potential of Nb-depleted α phase is the main reason of the poor corrosion resistance of DU and U-2.5 wt% Nb alloy. - Highlights: • New method (scanning Kelvin probe) was used to study the corrosion property. • Three types of corrosion morphologies were found after potentiodynamic polarization. • The effect of impurity elements on corrosion property was mentioned. • The corrosion mechanism of DU and U-Nb alloys was discussed.

Corrosion and alteration of materials from the nuclear industry; La Corrosion et l'alteration des materiaux du nucleaire

Energy Technology Data Exchange (ETDEWEB)

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.

2010-07-01

The control of the corrosion phenomenon is of prime importance for the nuclear industry. The efficiency and the safety of facilities can be affected by this phenomenon. The nuclear industry has to face corrosion for a large variety of materials submitted to various environments. Metallic corrosion operates in the hot and aqueous environment of water reactors which represent the most common reactor type in the world. Progresses made in the control of the corrosion of the different components of these reactors allow to improve their safety. Corrosion is present in the facilities of the back-end of the fuel cycle as well (corrosion in acid environment in fuel reprocessing plants, corrosion of waste containers in disposal and storage facilities, etc). The future nuclear systems will widen even more the range of materials to be studied and the situations in which they will be placed (corrosion by liquid metals or by helium impurities). Very often, corrosion looks like a patchwork of particular cases in its description. The encountered corrosion problems and their study are presented in this book according to chapters representing the main sectors of the nuclear industry and classified with respect to their phenomenology. This monograph illustrates the researches in progress and presents some results of particular importance obtained recently. Content: 1 - Introduction: context, stakes and goals; definition of corrosion; a complex science; corrosion in the nuclear industry; 2 - corrosion in water reactors - phenomenology, mechanisms, remedies: A - uniform corrosion: mechanisms, uniform corrosion of fuel cladding, in-situ measurement of generalized corrosion rate by electrochemical methods, uniform corrosion of nickel alloys, characterization of the passive layer and growth mechanisms, the PACTOLE code - an integrating tool, influence of water chemistry on corrosion and contamination, radiolysis impact on uniform corrosion; B - stress corrosion: stress corrosion cracking

The Effect of Friction Stir Welding on Corrosion Behavior of Ti-6Al-4V

Science.gov (United States)

Nasresfahani, Ali Reza; Soltanipur, Abdol Reza; Farmanesh, Khosro; Ghasemi, Ali

2017-09-01

Fusion welding can deteriorate corrosion behavior of Ti-6Al-4V alloy. However, the use of friction stir welding leads to a more appropriate corrosion resistance. In this study, the corrosion resistance of welded zones of Ti-6Al-4V alloy using friction stir welding technique is evaluated. For these purposes, the study of structural characteristics using SEM and FESEM equipped with EDS micro-analyses was conducted. Micro-hardness test was also employed to estimate the hardness of welded zones. Corrosion behavior was investigated by a potentiostat instrument. SEM micrographs, EDS and XRD analyses confirmed non-uniformity of chemical composition within the welded zones. The results reveal that the stir zone contains typical alpha and prior beta phases. Nevertheless, thermomechanical zone included equiaxed and bimodal lamellae structure. Furthermore, the presence of different types of phases and microstructure in the thermomechanical zone led to reduced corrosion resistance. The corresponding values of corrosion current density in the stir zone, thermomechanical zone and base metal were 0.048, 0.55 and 0.032 µA, respectively. Corresponding corrosion potential for these zones was estimated as -207, -110 and -157 mV. Evidently, the results show that corrosion resistance of thermomechanical zone is less than that of the stir zone and both zones have lower value than the base metal.

Effect of corrosion and sandblasting on the high cycle fatigue behavior of reinforcing B500C steel bars

Directory of Open Access Journals (Sweden)

Marina C. Vasco

2017-10-01

Full Text Available In a series of applications, steel reinforced concrete structures are subjected to fatigue loads during their service life, what in most cases happens in corrosive environments. Surface treatments have been proved to represent proper processes in order to improve both fatigue and corrosion resistances. In this work, the effect of corrosion and sandblasting on the high cycle fatigue behavior reinforcing steel bars is investigated. The investigated material is the reinforcing steel bar of technical class B500C, of nominal diameter of 12 mm. Steel bars specimens were first exposed to corrosion in alternate salt spray environment for 30 and 60 days and subjected to both tensile and fatigue tests. Then, a series of specimens were subjected to common sandblasting, corroded and mechanically tested. Metallographic investigation and corrosion damage evaluation regarding mass loss and martensitic area reduction were performed. Tensile tests were conducted after each corrosion exposure period prior to the fatigue tests. Fatigue tests were performed at a stress ratio, R, of 0.1 and loading frequency of 20 Hz. All fatigue tests series as well as tensile test were also performed for as received steel bars to obtain the reference behavior. The results have shown that sandblasting hardly affects the tensile behavior of the uncorroded material. The effect of sandblasting on the tensile behavior of pre-corroded specimens seems to be also limited. On the other hand, fatigue results indicate an improved fatigue behavior for the sandblasted material after 60 days of corrosion exposure. Martensitic area reductions, mass loss and depth of the pits were significantly smaller for the case of sandblasted materials, which confirms an increased corrosion resistance

Analysis of the Corrosion Behavior of an A-TIG Welded SS 409 Weld Fusion Zone

Science.gov (United States)

Vidyarthy, R. S.; Dwivedi, D. K.

2017-11-01

AISI 409 (SS 409) ferritic stainless steel is generally used as the thick gauge section in freight train wagons, in ocean containers, and in sugar refinery equipment. Activating the flux tungsten inert gas (A-TIG) welding process can reduce the welding cost during fabrication of thick sections. However, corrosion behavior of the A-TIG weld fusion zone is a prime concern for this type of steel. In the present work, the effect of the A-TIG welding process parameters on the corrosion behavior of a weld fusion zone made of 8-mm-thick AISI 409 ferritic stainless-steel plate has been analyzed. Potentiodynamic polarization tests were performed to evaluate the corrosion behavior. The maximum corrosion potential ( E corr) was shown by the weld made using a welding current of 215 A, a welding speed of 95 mm/min, and a flux coating density of 0.81 mg/cm2. The minimum E corr was observed in the weld made using a welding current of 190 A, a welding speed of 120 mm/min, and a flux coating density of 1.40 mg/cm2. The current study also presents the inclusive microstructure-corrosion property relationships using the collective techniques of scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray diffraction.

Effect of Flow Velocity on Corrosion Rate and Corrosion Protection Current of Marine Material

Energy Technology Data Exchange (ETDEWEB)

Lee, Seong Jong [Kunsan National University, Kunsan (Korea, Republic of); Han, Min Su; Jang, Seok Ki; Kim, Seong Jong [Mokpo National Maritime University, Mokpo (Korea, Republic of)

2015-10-15

In spite of highly advanced paint coating techniques, corrosion damage of marine metal and alloys increase more and more due to inherent micro-cracks and porosities in coatings formed during the coating process. Furthermore, flowing seawater conditions promote the breakdown of the protective oxide of the materials introducing more oxygen into marine environments, leading to the acceleration of corrosion. Various corrosion protection methods are available to prevent steel from marine corrosion. Cathodic protection is one of the useful corrosion protection methods by which the potential of the corroded metal is intentionally lowered to an immune state having the advantage of providing additional protection barriers to steel exposed to aqueous corrosion or soil corrosion, in addition to the coating. In the present investigation, the effect of flow velocity was examined for the determination of the optimum corrosion protection current density in cathodic protection as well as the corrosion rate of the steel. It is demonstrated from the result that the material corrosion under dynamic flowing conditions seems more prone to corrosion than under static conditions.

Corrosion behavior of electrodeposited Co-Fe alloys in aerated solutions

Energy Technology Data Exchange (ETDEWEB)

Chansena, A. [Research Unit on Corrosion, College of Data Storage Innovation, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Sutthiruangwong, S., E-mail: sutha.su@kmitl.ac.th [Department of Chemistry, Faculty of Science, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Research Unit on Corrosion, College of Data Storage Innovation, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand)

2017-05-01

Co-Fe alloy is an important component for reader-writer in hard disk drive. The surface of the alloy is exposed to the environment both in gas phase and in liquid phase during manufacturing process. The study of corrosion behavior of Co-Fe alloys can provide useful fundamental data for reader-writer production planning especially when corrosion becomes a major problem. The corrosion study of electrodeposited Co-Fe alloys from cyclic galvanodynamic polarization was performed using potentiodynamic polarization technique. The composition of electrodeposited Co-Fe alloys was determined by X-ray fluorescence spectrometry. The patterns from X-ray diffractometer showed that the crystal structure of electrodeposited Co-Fe alloys was body-centered cubic. A vibrating sample magnetometer was used for magnetic measurements. The saturation magnetization (M{sub s}) was increased and the intrinsic coercivity (H{sub ci}) was decreased with increasing Fe content. The corrosion rate study was performed in aerated deionized water and aerated acidic solutions at pH 3, 4 and 5. The corrosion rate diagram for Co-Fe alloys was constructed. It was found that the corrosion rate of Co-Fe alloys was increased with increasing Fe content in both aerated deionized water and aerated acidic solutions. In aerated pH 3 solution, the Co-Fe alloy containing 78.8% Fe showed the highest corrosion rate of 7.7 mm yr{sup −1} with the highest M{sub s} of 32.0 A m{sup 2} kg{sup −1}. The corrosion rate of the alloy with 23.8% Fe was at 1.1 mm yr{sup −1} with M{sub s} of 1.2 A m{sup 2} kg{sup −1}. In aerated deionized water, the alloy with the highest Fe content of 78.5% still showed the highest corrosion rate of 0.0059 mm yr{sup −1} while the alloy with the lowest Fe content of 20.4% gave the lowest corrosion rate of 0.0045 mm yr{sup −1}. - Highlights: • The aeration during corrosion measurement simulates reader-writer head production environment. • The corrosion rate diagram for Co-Fe alloys

Solution chemistry of Mo(III) and Mo(IV): Thermodynamic foundation for modeling localized corrosion

International Nuclear Information System (INIS)

Wang Peiming; Wilson, Leslie L.; Wesolowski, David J.; Rosenqvist, Joergen; Anderko, Andrzej

2010-01-01

To investigate the behavior of molybdenum dissolution products in systems that approximate localized corrosion environments, solubility of Mo(III) in equilibrium with solid MoO 2 has been determined at 80 deg. C as a function of solution acidity, chloride concentration and partial pressure of hydrogen. The measurements indicate a strong increase in solubility with acidity and chloride concentration and a weak effect of hydrogen partial pressure. The obtained results have been combined with literature data for systems containing Mo(III), Mo(IV), and Mo(VI) in solutions to develop a comprehensive thermodynamic model of aqueous molybdenum chemistry. The model is based on a previously developed framework for simulating the properties of electrolyte systems ranging from infinite dilution to solid saturation or fused salt limit. To reproduce the measurements, the model assumes the presence of a chloride complex of Mo(III) (i.e., MoCl 2+ ) and hydrolyzed species (MoOH 2+ , Mo(OH) 2 + , and Mo(OH) 3 0 ) in addition to the Mo 3+ ion. The model generally reproduces the experimental data within experimental scattering and provides a tool for predicting the phase behavior and speciation in complex, concentrated aqueous solutions. Thus, it provides a foundation for simulating the behavior of molybdenum species in localized corrosion environments.

RESEARCH OF FRUIT CONSERVES’ CORROSIVE AGGRESSIVENESS

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I. Kuznecova

2017-10-01

Full Text Available Corrosion of metal canning containers is one of the obstacles in spreading its application for packing of food. Particularly aggressive to the metal container is fruit canned medium, containing organic acids.The basic material for the production of metal canning container is white tinplate. The main advantage of white tinplate is the tin compounds are harmless to human organism. For this reason, a white badge is used widely, usually used for production of canning containers, packaging beverages. Despite the fact that recently often used containers made of aluminum badge (foil, the basic material for manufacturing metal canning containers is steel white tinplate.Now applied for coating paints and varnishes do not provide anti-corrosion protection of inner surface of metal containers during storage. Preserving of canned fruit quality in metal containers is largely defined corrosion resistance of the containers. This is due to the fact that the metal transition to canned fruit in due courses of corrosion processes is lowering the nutritional value and deterioration taste of the product, and while allocation of hydrogen is accompanied by swelling and destruction of metal containers.We have investigated a number of anti-corrosion coatings based on Fe-Cr and Fe-Sn-Ti of their behavior in aggressive mediums canned fruit. For the purpose of modeling such mediums the solutions of most widespread organic acids were used. The research allowed conclude, that in surface solid solutions Fe-Sn-Ti increase the corrosion resistance of carbon steel in aqueous solutions of malic, citric and tartaric acids. This implies that the surface solid solutions’ formation can significantly improve corrosion resistance in aggressive canning mediums.

The relative stress-corrosion-cracking susceptibility of candidate aluminum-lithium alloys for aerospace applications

Science.gov (United States)

Pizzo, P. P.

1982-01-01

Stress corrosion tests of Al-Li-Cu powder metallurgy alloys are described. Alloys investigated were Al-2.6% Li-1.4% and Al-2.6% Li-1.4% Cu-1.6% Mg. The base properties of the alloys were characterized. Process, heat treatment, and size/orientational effects on the tensile and fracture behavior were investigated. Metallurgical and electrochemical conditions are identified which provide reproducible and controlled parameters for stress corrosion evaluation. Preliminary stress corrosion test results are reported. Both Al-Li-Cu alloys appear more susceptible to stress corrosion crack initiation than 7075-T6 aluminum, with the magnesium bearing alloy being the most susceptible. Tests to determine the threshold stress intensity for the base and magnesium bearing alloys are underway. Twelve each, bolt loaded DCB type specimens are under test (120 days) and limited crack growth in these precracked specimens has been observed. General corrosion in the aqueous sodium chloride environment is thought to be obscuring results through crack tip blunting.

Synchrotron-based in situ soft X-ray microscopy of Ag corrosion in aqueous chloride solution

International Nuclear Information System (INIS)

Bozzini, B; D'Urzo, L; Gianoncelli, A; Kaulich, B; Kiskinova, M; Prasciolu, M; Tadjeddine, A

2009-01-01

In this paper we report an in situ X-ray microscopy study of a model metal electrochemistry system, incorporating faradaic reactivity: the anodic corrosion and cathodic electrodeposition of Ag in aqueous systems. The information at sub-μm scale about morpho-chemical evolution of the electrified interface, provided by this novel electroanalytical approach fosters fundamental understanding of important issues concerning material fabrication and stability, which are crucial in developing the next generation electrochemical technologies, such as fuel cells and biosensors. The key methodology challenge faced in this pilot electrochemical experiments is combining a three-electrode configuration and wet environment, which required metal electrodes suitable for transmitting soft X-rays and a sealed cell allowing working in high vacuum. This has been solved via lithographic fabrication route fabricating 75 nm thick Ag electrodes and using Si 3 N 4 membranes as X-ray windows and electrode support. Imaging in the STXM mode with phase contrast allowed us to monitor the corrosion morphologies and metal outgrowth features. Localised thickness variation and the build-up of reaction products of electron density different from that of the starting material have been detected with high sensitivity.

Long-term corrosion behaviors of Hastelloy-N and Hastelloy-B3 in moisture-containing molten FLiNaK salt environments

International Nuclear Information System (INIS)

Ouyang, Fan-Yi; Chang, Chi-Hung; Kai, Ji-Jung

2014-01-01

Highlights: •Corrosion behaviors of Hastelloy-N and -B3 in molten FLiNaK salt at 700 °C. •The alleviated corrosion rate of alloys was observed after long-hour immersion. •Long-term corrosion rate was limited by diffusion from matrix to alloy surface. •Corrosion pattern transferred from intergranular corrosion into general corrosion. •Presence of minor H 2 O did not greatly influence the long-term corrosion behavior. -- Abstract: This study investigated long-term corrosion behaviors of Ni-based Hastelloy-N and Hastelloy-B3 under moisture-containing molten alkali fluoride salt (LiF–NaF–KF: 46.5–11.5–42%) environment at an ambient temperature of 700 °C. The Hastelloy-N and Hastelloy-B3 experienced similar weight losses for tested duration of 100–1000 h, which was caused by aggregate dissolution of Cr and Mo into FLiNaK salts. The corrosion rate of both alloys was high initially, but then reduced during the course of the test. The alleviated corrosion rate was due to the depletion of Cr and Mo near surface of the alloys and thus the long-term corrosion rate was controlled by diffusion of Cr and Mo outward to the alloy surface. The results of microstructural characterization revealed that the corrosion pattern for both alloys tended to be intergranular corrosion at early stage of corrosion test, and then transferred to general corrosion for longer immersion hours

Prediction of Corrosion of Alloys in Mixed-Solvent Environments

Energy Technology Data Exchange (ETDEWEB)

Anderko, Andrzej [OLI Systems Inc. Morris Plains (United States); Wang, Peiming [OLI Systems Inc. Morris Plains (United States); Young, Robert D. [OLI Systems Inc. Morris Plains (United States); Riemer, Douglas P. [OLI Systems Inc. Morris Plains (United States); McKenzie, Patrice [OLI Systems Inc. Morris Plains (United States); Lencka, Malgorzata M. [OLI Systems Inc. Morris Plains (United States); Babu, Sudarsanam Suresh [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Angelini, Peter [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2003-06-05

Corrosion is much less predictable in organic or mixed-solvent environments than in aqueous process environments. As a result, US chemical companies face greater uncertainty when selecting process equipment materials to manufacture chemical products using organic or mixed solvents than when the process environments are only aqueous. Chemical companies handle this uncertainty by overdesigning the equipment (wasting money and energy), rather than by accepting increased risks of corrosion failure (personnel hazards and environmental releases). Therefore, it is important to develop simulation tools that would help the chemical process industries to understand and predict corrosion and to develop mitigation measures. To create such tools, we have developed models that predict (1) the chemical composition, speciation, phase equilibria, component activities and transport properties of the bulk (aqueous, nonaqueous or mixed) phase that is in contact with the metal; (2) the phase equilibria and component activities of the alloy phase(s) that may be subject to corrosion and (3) the interfacial phenomena that are responsible for corrosion at the metal/solution or passive film/solution interface. During the course of this project, we have completed the following: (1) Development of thermodynamic modules for calculating the activities of alloy components; (2) Development of software that generates stability diagrams for alloys in aqueous systems; these diagrams make it possible to predict the tendency of metals to corrode; (3) Development and extensive verification of a model for calculating speciation, phase equilibria and thermodynamic properties of mixed-solvent electrolyte systems; (4) Integration of the software for generating stability diagrams with the mixed-solvent electrolyte model, which makes it possible to generate stability diagrams for nonaqueous or mixed-solvent systems; (5) Development of a model for predicting diffusion coefficients in mixed-solvent electrolyte

Effect of Nitrite Inhibitor on the Macrocell Corrosion Behavior of Reinforcing Steel

Directory of Open Access Journals (Sweden)

Zhonglu Cao

2015-01-01

Full Text Available The effect of nitrite ions on the macrocell corrosion behavior of reinforcing steel embedded in cement mortar was investigated by comparing and analyzing the macrocell corrosion current, macrocell polarization ratios, and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was analyzed, and the mechanism of macrocell corrosion affected by nitrite ions was proposed. The results indicated that nitrite ions had significant impact on the macrocell polarization ratios of cathode and anode. The presence of nitrite could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the anode.

Control of corrosion in an aqueous nuclear fuel storage basin

International Nuclear Information System (INIS)

Zimmerman, C.A.

1981-01-01

Observations made during thirty years of experience in operating a nuclear fuel storage basin, used for storing a wide variety of spent nuclear fuels underwater have identified several forms of corrosion such as galvanic, pitting and crevice attack. Examples of some of the forms of corrosion observed and their causes are discussed, along with the measures taken to mitigate the corrosive attack. The paper also describes the procedure used to reduce corrosion by: surveillance of design, selection of materials for application in the basin, and inspection of items in the storage basin

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)

Effects of laser shock peening on stress corrosion behavior of 7075 aluminum alloy laser welded joints

Energy Technology Data Exchange (ETDEWEB)

Wang, J.T., E-mail: jiasqq1225@126.com [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Materials Engineering, Jiangsu University of Technology, Changzhou 213001 (China); Zhang, Y.K. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Mechanical Engineering, Southeast University, Nanjing 211189 (China); Chen, J.F.; Zhou, J.Y.; Ge, M.Z.; Lu, Y.L.; Li, X.L. [School of Materials Engineering, Jiangsu University of Technology, Changzhou 213001 (China)

2015-10-28

7075 aluminum alloy weldments were processed by an intensive process known as laser shock peening (LSP), meanwhile its stress corrosion behaviors were observed by scanning electron microscopy (SEM) and slow strain rate tensile (SSRT) tests. Results showed that the effect of LSP on corrosion behavior of the joint was fairly useful and obvious. With LSP, the elongation, time of fracture and static toughness after the SSRT test were improved by 11.13%, 20% and 100%, respectively. At the same time, the location of the fracture also changed. LSP led to a transition of the fracture type from transgranular to intergranular The reasons for these enhancements of the joint on corrosion behavior were caused by microstructure, residual stress, micro-hardness, and fracture appearance.

Corrosion Behavior of Three Nanoclay Dispersion Methods of Epoxy/Organoclay Nanocomposites

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Wiwat Keyoonwong

2012-01-01

Full Text Available The aims of this study, firstly, to obtain high degree of clay exfoliation in the epoxy matrix by three dispersion methods such as normal mixing, shear mixing, and high-speed mixing and, secondly, to investigate corrosion behavior of epoxy/organoclay nanocomposite, immersion test, weight change, and penetration behavior were conducted. From the three mixing methods, the high-speed mixing method showed larger clay interlayer distance, smaller clay aggregate, and more homogeneity and expectedly resulted in high anticorrosive properties. Penetration depths of these nanocomposites showed a small difference; however, the most noticeable improvements in anticorrosion performance for epoxy/organoclay nanocomposites under high-speed mixing method were found to reduce penetration and weight uptake which are described via the model of nanoparticulate-filled structure and discussed in corrosion protection mechanism against environmental liquid penetration.

Fretting Corrosion Behavior of Experimental Ti-20Cr Compared to Titanium.

Science.gov (United States)

Sawada, Tomofumi; Schille, Christine; Almadani, Atif; Geis-Gerstorfer, Jürgen

2017-02-17

Experimental cast titanium alloys containing 20 mass% chromium (Ti-20Cr) show preferable mechanical properties and a good corrosion resistance. This study evaluated the fretting corrosion behavior of Ti-20Cr. Ti-20Cr ( n = 4) and commercially pure titanium (CP-Ti, n = 6) disk specimens were used. The fretting corrosion test was performed by electrochemical corrosion at 0.3 V in 0.9% saline solution and mechanical damage using 10 scratching cycles with three different scratching speeds (10-40 mm/s) at 10 N. After testing, the activation peak, repassivation time and surface morphology of each specimen were analyzed. The differences between the results were tested by parametric tests (α = 0.05). The average activation peaks were significantly higher in CP-Ti than in Ti-20Cr ( p Ti. Slight differences in the repassivation time were observed between the materials at every scratching speed; faster scratching speeds showed shorter repassivation times in both materials ( p Ti showed severe damage and significantly higher wear depth than Ti-20Cr ( p < 0.05). In conclusion, adding chromium to titanium reduced surface damage and improved the fretting corrosion resistance.

Long-term corrosion studies

International Nuclear Information System (INIS)

Gdowski, G.

1998-01-01

The scope of this activity is to assess the long-term corrosion properties of metallic materials under consideration for fabricating waste package containers. Three classes of metals are to be assessed: corrosion resistant, intermediate corrosion resistant, and corrosion allowance. Corrosion properties to be evaluated are general, pitting and crevice corrosion, stress-corrosion cracking, and galvanic corrosion. The performance of these materials will be investigated under conditions that are considered relevant to the potential emplacement site. Testing in four aqueous solutions, and vapor phases above them, and at two temperatures are planned for this activity. (The environmental conditions, test metals, and matrix are described in detail in Section 3.0.) The purpose and objective of this activity is to obtain the kinetic and mechanistic information on degradation of metallic alloys currently being considered for waste package containers. This information will be used to provide assistance to (1) waste package design (metal barrier selection) (E-20-90 to E-20-92), (2) waste package performance assessment activities (SIP-PA-2), (3) model development (E-20-75 to E-20-89). and (4) repository license application

Effect of Aging Temperature on Corrosion Behavior of Sintered 17-4 PH Stainless Steel in Dilute Sulfuric Acid Solution

Science.gov (United States)

Szewczyk-Nykiel, Aneta; Kazior, Jan

2017-07-01

The general corrosion behavior of sintered 17-4 PH stainless steel processed under different processing conditions in dilute sulfuric acid solution at 25 °C was studied by open-circuit potential measurement and potentiodynamic polarization technique. The corrosion resistance was evaluated based on electrochemical parameters, such as polarization resistance, corrosion potential, corrosion current density as well as corrosion rate. The results showed that the precipitation-hardening treatment could significantly improve the corrosion resistance of the sintered 17-4 PH stainless steel in studied environment. As far as the influence of aging temperature on corrosion behavior of the sintered 17-4 PH stainless steel is concerned, polarization resistance and corrosion rate are reduced with increasing aging temperature from 480 up to 500 °C regardless of the temperature of solution treatment. It can be concluded that the highest corrosion resistance in 0.5 M H2SO4 solution exhibits 17-4 PH after solution treatment at 1040 °C followed by aging at 480 °C.

Corrosion of NdFeB permanent magnet materials

International Nuclear Information System (INIS)

Warren, G.W.; Gao, G.; Li, Q.

1991-01-01

NdFeB is an important class of new magnetic materials, however corrosion resistance is a serious concern and literature on the electrochemical behavior of NdFeB is scarce. This paper reports the results of an electrochemical investigation of the corrosion behavior of sintered NdFeB magnets obtained from three manufacturers. Linear polarization (cyclic voltammetry) experiments were conducted in aqueous solutions ranging in pH from 0.7 to 13.5. A limited degree of passivation was observed in all solutions which is believed to be due to the formation of a complex Fe-Nd oxide and/or hydroxide film. The presence of a small amount of chloride ion, 10 to 100 ppm, shows only a slight effect, but higher concentrations (1000 ppm) cause a total breakdown in passivity and a dramatic increase in anodic current. The cathodic potential sweep shows an abrupt and unusual oxidation process, giving rise to an oxidation peak not commonly seen. This peak may result from dissolution of the film or preferential attack of intergranular phases

Corrosion Behavior of Heat-Treated AlSi10Mg Manufactured by Laser Powder Bed Fusion

Directory of Open Access Journals (Sweden)

Marina Cabrini

2018-06-01

Full Text Available This experimental work is aimed at studying the effect of microstructural modifications induced by post-processing heat treatments on the corrosion behavior of silicon-aluminum alloys produced by means of laser powder bed fusion (LPBF. The manufacturing technique leads to microstructures characterized by the presence of melt pools, which are quite different compared to casting alloys. In this study, the behavior of an AlSi10Mg alloy was evaluated by means of intergranular corrosion tests according to ISO 11846 standard on heat-treated samples ranging from 200 to 500 °C as well as on untreated samples. We found that temperatures above 200 °C reduced microhardness of the alloy, and different corrosion morphologies occurred due to the modification of both size and distribution of silicon precipitates. Selective penetrating attacks occurred at melt pool borders. The intergranular corrosion phenomena were less intense for as-produced specimens without heat treatments compared to the heat-treated specimens at 200 and 300 °C. General corrosion morphologies were noticed for specimens heat treated at temperatures exceeding 400 °C.

Influence of heat treatment on the machinability and corrosion behavior of AZ91 Mg alloy

Directory of Open Access Journals (Sweden)

Swetha Chowdary V

2018-03-01

Full Text Available In the present study, AZ91 Mg alloy was heat treated at 410 °C for 6, 12 and 24 h to investigate the influence of heat treatment on machinability and corrosion behavior. The effect of soaking time on the amount and distribution of Mg17Al12 (β – phase was analyzed under the optical microscope. Microhardness measurements demonstrated the increased hardness with increased heat treatment soaking time, which can be attributed to the solid solution strengthening. The influence of super saturated α-grains on reducing the cutting force (Fz with respect to increased cutting speed was observed as prominent. The corrosion behavior of the heat treated specimens was studied by conducting electrochemical tests. Surprisingly, corrosion rate of heat treated samples was observed as increased compared with the base material. From the results, it is evident that the machinability of AZ91 Mg alloy can be improved by producing super saturated α-grains through heat treatment but at the cost of losing corrosion resistance. Keywords: AZ91 Mg alloy, Solid solution, Turning, Corrosion, Machinability

Electrochemical Corrosion Behavior of Low Carbon I-Beam Steels In Simulated Yucca Mountain Repository Environment

Energy Technology Data Exchange (ETDEWEB)

Arjunan, Venugopal; Lamb, Joshua; Chandra, Dhanesh; Daemen, Jack; Jones, Denny A.; Engelhard, Mark H.; Lea, Alan S.

2005-04-01

The electrochemical corrosion behavior of low carbon steel was examined in a simulated Yucca Mountain (YM) ground water by varying the electrolyte concentration and temperature under aerated and deaerated conditions. The results show that in deaerated conditions, the corrosion rate is low in the order of 0.6 to 4.5mpy, between 25 to 85 C, respectively. However, in aerated conditions the measured rates were expectedly very high, in the order of 3-55mpy in the above mentioned temperature levels. The rates initially increased up to 45 C, and a decreasing trend was observed with further increase in temperature from 65 to 85 C. The maximum corrosion rate was occurred at 45 C (54.5mpy). The low corrosion rates observed in all deaerated conditions, and in aerated solutions at higher temperatures were due to the preferential adsorption of Mg-species on the steel surface, as identified by XPS analyses. The results also indicate possible localized corrosion behavior of carbon steel in aerated conditions up to 45 C.

Electrochemical Corrosion Behavior of Low Carbon I-Beam Steels In Simulated Yucca Mountain Repository Environment

International Nuclear Information System (INIS)

Arjunan, Venugopal; Lamb, Joshua; Chandra, Dhanesh; Daemen, Jack; Jones, Denny A.; Engelhard, Mark H.; Lea, Alan S.

2005-01-01

The electrochemical corrosion behavior of low carbon steel was examined in a simulated Yucca Mountain (YM) ground water by varying the electrolyte concentration and temperature under aerated and deaerated conditions. The results show that in deaerated conditions, the corrosion rate is low in the order of 0.6 to 4.5mpy, between 25 to 85 C, respectively. However, in aerated conditions the measured rates were expectedly very high, in the order of 3-55mpy in the above mentioned temperature levels. The rates initially increased up to 45 C, and a decreasing trend was observed with further increase in temperature from 65 to 85 C. The maximum corrosion rate was occurred at 45 C (54.5mpy). The low corrosion rates observed in all deaerated conditions, and in aerated solutions at higher temperatures were due to the preferential adsorption of Mg-species on the steel surface, as identified by XPS analyses. The results also indicate possible localized corrosion behavior of carbon steel in aerated conditions up to 45 C

Corrosion behavior of CLAM steel weldment in flowing liquid Pb-17Li at 480 °C

International Nuclear Information System (INIS)

Chen Xizhang; Shen Zheng; Chen Xing; Lei Yucheng; Huang Qunying

2011-01-01

Highlights: ► The research shows that the CLAM steel weldment have its own corrosion mechanism in liquid Pb-17Li alloy. The basic rule of the corrosion behaviour of weldments is that the coorosion rate decreases obviously with the increasing of exposed time. ► The weight loss of CLAM steel weldment is far higer than the base metal after exposed to Pb-17Li alloy. Corrosion has little effects on elements of weldment sample surfaces. And an easier corrosion area in the weld joint are found. ► A simple presumably corrosion behavior model is established. The model demonstrate that the easier corroded area will be formed when the direction of martensite laths form small-angle with the specimen surface, The easy corrosion area is the martensite lath area lack of Cr and distributes like laths, the cross-section area is 1 μm 2 to 4 μm 2, the existence of the easier corrosion area is one of the reasons that lead to the difference of the corrosion rate. - Abstract: CLAM (China Low Activation Martensitic) steel is considered as one of the candidate structural materials in liquid LiPb blanket concepts. Welding is one of the essential technologies for its practical application, CLAM steel weldment shows a great difference with base metal due to the effect of welding thermal cycle. In order to investigate the corrosion behavior and mechanism of CLAM weldments in liquid Pb-17Li, the experiments were performed by exposing the TIG weldment samples in flowing LiPb at 480 °C. The weight loss test of exposed specimens show that in 500 h, 1000 h dynamic conditions, corrosion resistance of CLAM steel weldment is poor, SEM analysis shows that the thicker martensite lath in weld area lead to higher corrosion amount, EDS results show that the influence of corrosion on surface elements is small, and surface corrosion is even, EDX analysis shows that the penetration of Pb-17Li does not exist in the joint. With the increasing of exposure time, the corrosion rate decreases

Microbiologically induced corrosion

International Nuclear Information System (INIS)

Stein, A.A.

1988-01-01

Biological attack is a problem that can affect all metallic materials in a variety of environments and systems. In the power industry, corrosion studies have focused on condensers and service water systems where slime, barnacles, clams, and other macro-organisms are easily detected. Efforts have been made to eliminate the effect of these organisms through the use of chlorination, backflushing, organic coating, or thermal shock. The objective is to maintain component performance by eliminating biofouling and reducing metallic corrosion. Recently, corrosion of power plant components by micro-organisms (bacteria) has been identified even in very clean systems. A system's first exposure to microbiologically induced corrosion (MIC) occurs during its first exposure to an aqueous environment, such as during hydrotest or wet layup. Corrosion of buried pipelines by sulfate-reducing bacteria has been studied by the petrochemical industry for years. This paper discusses various methods of diagnosing, monitoring, and controlling MIC in a variety of systems, as well as indicates areas where further study is needed

Hydrogen generation by aluminum corrosion in aqueous alkaline solutions of inorganic promoters: The AlHidrox process

International Nuclear Information System (INIS)

Macanas, Jorge; Soler, Lluis; Candela, Angelica Maria; Munoz, Maria; Casado, Juan

2011-01-01

The research of alternative processes to obtain clean fuels has become a main issue because of the concerns related to the current energy system, both from economical and environmental points of view. Hydrogen storage and production methods are being investigated for stationary and portable applications. Up to now, a significant part of H 2 production on demand was thought to be fulfilled by using chemical hydrides, but recent studies have proved the limitations of this approach. Conversely, H 2 production based in the corrosion of light metals in water solutions is an interesting alternative. Among all of them, Al is probably the most adequate metal for energetic purposes due to its high electron density and oxidation potential. But concerning H 2 production from Al corrosion in water, a major issue remains unsolved: metal passivation due to the formation of Al(OH) 3 inhibits H 2 evolution. In this work we show the last results obtained for the generation of H 2 from water using Al powder using diverse alkaline solutions. It is confirmed that corrosion is not affected solely by the solution pH but also by the nature of the ionic species found in the aqueous medium. Moreover, we describe the AlHidrox process, which minimizes Al passivation under mild conditions by the addition of different inorganic salts as corrosion promoters, allowing 100% yields and flow rates up to 2.9 L/min per gram of Al. The feasibility of the process has been regarded in terms of stability (by conducting several successive runs) and self-initiation without an external heating. -- Highlights: → The AlHidrox process minimizes Al passivation by the addition of inorganic salts. → Al corrosion to produce H 2 greatly depends on the nature of the dissolved species. → The maximum flow achieved was 2.9 dm 3 H 2 min -1 .per gram of Al using Fe 2 (SO 4 ) 3 . → We found conditions to start up H 2 generation without external energy input.

Corrosion behavior of materials selected for FMIT lithium system

International Nuclear Information System (INIS)

Bazinet, G.D.; Down, M.G.; Matlock, D.K.

1983-01-01

The corrosion program consisted of a multi-disciplinary approach utilizing the liquid lithium test resources and capabilities of several laboratories. Specific concerns associated with the overall objective of materials corrosion behavior were evaluated at each laboratory. Testing conditions included: approx. 3700 hours of exposure to flowing lithium at temperatures from 230 0 C to 270 0 C and approx. 6500 hours of exposure to flowing lithium at an isothermal temperature of 270 0 C. Principal areas of investigation, to be discussed here briefly, included lithium corrosion effects on the following: (1) types 304 and 304L austenitic stainless steels, which are specified as reference materials for the FMIT lithium system; (2) type 304 stainless steel weldments (w/type 308 stainless steel filler) typical of specified tube and butt welds in the lithium system design; (3) titanium, zirconium and yttrium, which represent potential hot trap getter materials; (4) BNi4 braze alloy, used as a potential attachement method in the plug/seat fabrication of liquid lithium valves; and (5) type 321 stainless steel bellows, typical of bellows used in potential liquid lithium valve designs

Characterization of the corrosion products formed on mild steel in acidic medium with N-octadecylpyridinium bromide as corrosion inhibitor

Energy Technology Data Exchange (ETDEWEB)

Nava, N., E-mail: tnava@imp.mx; Likhanova, N. V. [Direccion de Investigacion y Posgrado, Instituto Mexicano del Petroleo (Mexico); Olivares-Xometl, O. [Benemerita Universidad Autonoma de Puebla, Facultad de Ingenieria Quimica (Mexico); Flores, E. A. [Direccion de Investigacion y Posgrado, Instituto Mexicano del Petroleo (Mexico); Lijanova, I. V. [CIITEC, Instituto Politecnico Nacional (Mexico)

2011-11-15

The characterization of the corrosion products formed on mild steel SAE 1018 after 2 months exposure in aqueous sulfuric acid with and without corrosion inhibitor N-octadecylpyridinium bromide has been carried out by means of transmission {sup 57}Fe Moessbauer spectroscopy and X-ray powder diffraction (XRD). The major constituent of the rust formed in this environment without corrosion inhibitor is goethite ({alpha}-FeOOH). The samples with N-octadecylpyridinium bromide contain rozenite and large amounts of melanterite in the corrosion layers.

Effects of external stresses on hot corrosion behavior of stainless steel TP347HFG

International Nuclear Information System (INIS)

Fu, Jiapeng; Zhou, Qulan; Li, Na; Liu, Zhuhan; Liu, Taisheng

2016-01-01

Highlights: • Hot corrosion tests of TP347HFG under different stresses were conducted. • The corrosion resistance was strengthened by the exertion of tensile stresses. • External stresses promoted faster formation of the protective Cr_2O_3 layer. • Specimens under critical stress 40 MPa condition present the best resistance. - Abstract: Hot corrosion experiments of alloy TP347HFG under different stresses were conducted. Corroded specimens were examined by means of corrosion products, morphology and compositional changes in corrosion scales. The corrosion behavior was strongly associated with the formation of oxides layers. The corrosion resistance was strengthened by the external stress. It seemed that the exertion of stresses caused many micro cracks and defects, which acted as faster and easier diffusion paths for Cr atoms to diffuse to the surface, and thus, promote faster formation of the protective Cr_2O_3 oxide layer. Critical stress 40 MPa was found, specimens under which present the best resistance.

Corrosion behavior of low energy, high temperature nitrogen ion ...

Indian Academy of Sciences (India)

Corrosion behavior of low energy, high temperature nitrogen ion-implanted AISI 304 stainless steel. M GHORANNEVISS1, A SHOKOUHY1,∗, M M LARIJANI1,2,. S H HAJI HOSSEINI 1, M YARI1, A ANVARI4, M GHOLIPUR SHAHRAKI1,3,. A H SARI1 and M R HANTEHZADEH1. 1Plasma Physics Research Center, Science ...

Influence of the casting processing route on the corrosion behavior of dental alloys.

Science.gov (United States)

Galo, Rodrigo; Rocha, Luis Augusto; Faria, Adriana Claudia; Silveira, Renata Rodrigues; Ribeiro, Ricardo Faria; de Mattos, Maria da Gloria Chiarello

2014-12-01

Casting in the presence of oxygen may result in an improvement of the corrosion performance of most alloys. However, the effect of corrosion on the casting without oxygen for dental materials remains unknown. The aim of this study was to investigate the influence of the casting technique and atmosphere (argon or oxygen) on the corrosion behavior response of six different dental casting alloys. The corrosion behavior was evaluated by electrochemical measurements performed in artificial saliva for the different alloys cast in two different conditions: arc melting in argon and oxygen-gas flame centrifugal casting. A slight decrease in open-circuit potential for most alloys was observed during immersion, meaning that the corrosion tendency of the materials increases due to the contact with the solution. Exceptions were the Co-based alloys prepared by plasma, and the Co-Cr-Mo and Ni-Cr-4Ti alloys processed by oxidized flame, in which an increase in potential was observed. The amount of metallic ions released into the artificial saliva solution during immersion was similar for all specimens. Considering the pitting potential, a parameter of high importance when considering the fluctuating conditions of the oral environment, Co-based alloys show the best performance in comparison with the Ni-based alloys, independent of the processing route. Copyright © 2014 Elsevier B.V. All rights reserved.

Corrosion monitoring of iron, protected by an organic coating, with the aid of impedance measurements

International Nuclear Information System (INIS)

Hubrecht, J.; Piens, M.; Vereecken, J.

1984-01-01

The ac impedance measurement has proved to be a useful electrochemical technique for mainly qualitative studies of electrochemical and corrosion systems. Even for complicated systems such as coated metals in corrosive environments this technique has been used with success. The system chosen for the present study is an ARMCO iron plate, coated with a SrCrO 4 -pigmented styrene acrylic polymer, and immersed for several weeks in an aqueous NaCl solution. Impedance measurements analyze a system under test into its constituting phenomena. The dependence of system parameters on coating layer thickness, NaCl concentration, and pigmentation of the coating during the immersion time provides insight into the corrosion and protection mechanisms at the coating/metal interface, besides the behavior of the coating itself

Investigation of electrochemical corrosion behavior in a 3.5 wt.% NaCl solution of boronized dual-phase steel

International Nuclear Information System (INIS)

Kayali, Yusuf; Anaturk, Bilal

2013-01-01

Highlights: ► Corrosion behaviors in a 3.5% NaCl solution of boronized Dual-Phase (DP) steels were examined. ► The martensite ratio increased with an increase in the intercritical annealing temperature. ► The corrosion resistance decreased with increase of the martensite ratio. ► The boride layer increased the corrosion resistance of DP steel 2–3-fold. ► The superior properties of DP steel as well as poor corrosion properties were improved by the boriding process. - Abstract: In this study, corrosion behaviors of boronized and non-boronized dual-phase steel were investigated with Tafel extrapolation and linear polarization methods in a 3.5 wt.% NaCl solution. Microstructure analyses show that the boride layer on the dual-phase steel surface had a flat and saw smooth morphology. It was detected by X-ray diffraction (XRD) analysis that the boride layer contained FeB and Fe 2 B phases. The amount of martensite increases with an increase in the intercritical annealing temperature. Both the amount of martensite and the morphology of the phase constituents have an influence on the corrosion behavior of dual-phase steel. A higher corrosion tendency was observed with an increased amount of martensite. The corrosion resistance of boronized dual-phase steel is higher compared with that of dual-phase steel

Corrosion of steel tendons in concrete pressure vessels: review of recent literature and experimental investigations

International Nuclear Information System (INIS)

Griess, J.C.

1978-01-01

The fundamentals of localized corrosion are briefly discussed, and the literature concerning corrosion of carbon steel in aqueous environments, in particular the stress-corrosion cracking of carbon steels, is reviewed. The behavior of high strength steels in specific environments, including concrete and organic substances, is also summarized. The available information indicates that the corrosion of steels in correctly formulated concrete is minimal. Even appreciable concentrations of chloride, sulfate, sulfide, and nitrate salts can be tolerated in the concrete or grout without detrimental effects. Adherence to established standards in the preparation and application of grouts in tendon-bearing conduits should guarantee very long tendon lifetimes. Little is reported about the behavior of tendons in proprietary organic greases or waxes, but very good corrosion resistance is expected if the organic material remains intact. Stress-corrosion cracking tests performed with AISI 1080 steel tendon wires, using the constant-strain-rate method, produced results expected from data in the literature. Cracking was observed only in neutral or acid solutions containing hydrogen sulfide, in ammonium nitrate solutions, and possibly in a dilute solution of sodium bisulfite. General corrosion tests in water and in dilute solutions of sodium nitrate, chloride, or sulfate showed that oxygen was an important factor; corrosion was substantially greater when oxygen had free access to the solution than when access to oxygen was restricted. In the tests with oxygen the heaviest attack on the steel tendons was at the waterline of the solution

The effect of molybdenum on the corrosion behaviour of the high-entropy alloys Co1.5CrFeNi1.5Ti0.5Mox in aqueous environments

International Nuclear Information System (INIS)

Chou, Y.L.; Yeh, J.W.; Shih, H.C.

2010-01-01

The purpose of this study is to investigate the electrochemical properties of the Co 1.5 CrFeNi 1.5 Ti 0.5 Mo x high-entropy alloys in three aqueous environments which simulate acidic, marine, and basic environments at ambient temperature (∼25 o C). The potentiodynamic polarisation curves of the Co 1.5 CrFeNi 1.5 Ti 0.5 Mo x alloys, obtained in aqueous solutions of H 2 SO 4 and NaOH, clearly revealed that the corrosion resistance of the Mo-free alloy was superior to that of the Mo-containing alloys. On the other hand, the lack of hysteresis in cyclic polarisation tests and SEM micrographs confirmed that the Mo-containing alloys are not susceptible to pitting corrosion in NaCl solution.

THE CORROSION BEHAVIOR AND WEAR RESISTANCE OF GRAY CAST IRON

Directory of Open Access Journals (Sweden)

Lina F. Kadhim

2018-01-01

Full Text Available Gray cast iron has many applications as pipes , pumps and valve bodies where it has influenced by heat and contact with other solutions . This research has studied the corrosion behavior and Vickers hardness of gray cast iron by immersion in four strong alkaline solutions (NaOH, KOH, Ca(OH2, LiOHwith three concentrations (1%,2%,3% of each solution. Dry sliding wear has carried out before and after the heat treatments (stress relief ,normalizing, hardening and tempering. In this work ,maximum wear strength has obtained at tempered gray cast iron and minimum corrosion rate has obtained in LiOH solution by forming protective white visible oxide layer.

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

Corrosion Behavior of Superalloys in Hot Lithium Molten Salt

International Nuclear Information System (INIS)

Cho, Soo-Haeng; Hur, Jin-Mok; Seo, Chung-Seok; Park, Seoung-Won

2006-01-01

The Li-reduction process involves the chemical reduction of spent fuel oxides by liquid lithium metal in a molten LiCl salt bath at 650 .deg. C followed by a separate electrochemical reduction of lithium oxide (Li 2 O), which builds up in the salt bath. This process requires a high purity inert gas atmosphere inside remote hot cell nuclear facility to prevent unwanted Li oxidation and fires during the handling of chemically active Li metal. In light of the limitations of the Li-reduction process, a direct electrolytic reduction technology is being developed by KAERI to enhance process safety and economic viability. The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. Even so, the electrochemical process vessel must be resilient at ∼ 650 .deg. C in the presence of oxygen to enable high processing rates and an extended service life. But, the mechanism and the rate of the corrosion of metals in LiCl-Li 2 O molten salt under oxidation condition are not clear. In the present work, the corrosion behavior and corrosion mechanism of superalloys have been studied in the molten salt of LiCl-Li 2 O under oxidation condition

Microstructure, Corrosion and Magnetic Behavior of an Aged Dual-Phase Stainless Steel

Science.gov (United States)

Ziouche, A.; Haddad, A.; Badji, R.; Zergoug, M.; Zoubiri, N.; Bedjaoui, W.; Abaidia, S.

2018-03-01

In the present work, the effect of the precipitation phenomena on corrosion and magnetic behavior of an aged dual-phase stainless steel was investigated. Aging treatment caused the precipitation of the σ phase, chromium carbides and secondary austenite, which was accompanied by the shifting of the δ/γ interfaces inside the δ ferrite grains. Aging between 700 and 850 °C strongly deteriorated the pitting corrosion resistance of the studied material. Magnetic investigation of the aged material using the vibration sample magnetic technique revealed the sensitivity of the intrinsic magnetic properties to the smallest microstructural change. This was confirmed by the Eddy current technique that led also to the evaluation of the aging-induced localized corrosion.

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

Effect of Plastic Deformation on the Corrosion Behavior of a Super-Duplex Stainless Steel

Science.gov (United States)

Renton, Neill C.; Elhoud, Abdu M.; Deans, William F.

2011-04-01

The role of plastic deformation on the corrosion behavior of a 25Cr-7Ni super-duplex stainless steel (SDSS) in a 3.5 wt.% sodium chloride solution at 90 °C was investigated. Different levels of plastic strain between 4 and 16% were applied to solution annealed tensile specimens and the effect on the pitting potential measured using potentiodynamic electrochemical techniques. A nonlinear relationship between the pitting potential and the plastic strain was recorded, with 8 and 16% causing a significant reduction in average E p, but 4 and 12% causing no significant change when compared with the solution-annealed specimens. The corrosion morphology revealed galvanic interaction between the anodic ferrite and the cathodic austenite causing preferential dissolution of the ferrite. Mixed potential theory and the changing surface areas of the two phases caused by the plastic deformation structures explain the reductions in pitting potential at certain critical plastic strain levels. End-users and manufacturers should evaluate the corrosion behavior of specific cold-worked duplex and SDSSs using their as-produced surface finishes assessing in-service corrosion performance.

The effect of brazing parameters on corrosion behavior of brazed aluminum joints

Science.gov (United States)

Ghasimakbari, Farzam; Hadian, Ali Mohammad; Ershadrad, Soheil; Omidazad, Amir Mansour

2018-01-01

Fluid transmission pipes made of aluminum are widely used in petrochemical industries. For many applications, they have to be brazed to each other. The brazed joints, in many cases, are encountered with corrosive medias. This paper reports a part of a work to investigate the corrosion behavior of brazed AA6061 using AA4047 as filler metal with and without the use of flux under different brazing atmospheres. The samples brazed under air, vacuum, argon, and hydrogen atmospheres. The interfacial area of the joints was examined to ensure being free of any defects. The sides of each test piece were covered with an insulator and the surface of the joint was encountered to polarization test. The results revealed a significant difference of corrosion resistance. The samples that brazed under argon and hydrogen atmospheres had better corrosion resistance than other samples. The microstructure of the corroded joints revealed that the presence of defects, impurities due to use of flux and depth of filter metal penetration in base metal are crucial variables on the corrosion resistance of the joints.

Aqueous stress-corrosion cracking of high-toughness D6AC steel

Science.gov (United States)

Gilbreath, W. P.; Adamson, M. J.

1976-01-01

The crack growth behavior of D6AC steel as a function of stress intensity, stress and corrosion history, and test technique, under sustained load in filtered natural seawater, 3.3 per cent sodium chloride solution, and distilled water, was investigated. Reported investigations of D6AC were considered in terms of the present study with emphasis on thermal treatment, specimen configuration, fracture toughness, crack-growth rates, initiation period, and threshold. Both threshold and growth kinetics were found to be relatively insensitive to these test parameters. The apparent incubation period was dependent on technique, both detection sensitivity and precracking stress intensity level.

Microstructure and Corrosion Behavior of Laser Synthesized Cobalt Based Powder on Ti-6Al-4V

Science.gov (United States)

Adesina, O. S.; Popoola, A. P. I.; Pityana, S. L.; Oloruntoba, D. T.

2018-05-01

The corrosion behavior of titanium alloys when used for various dynamic offshore components has been a major concern of titanium drilling risers in deepwater energy extraction. A way of achieving specified requirement is the development of coatings suitable to protect the base material against corrosion. In this work, laser cladding technique which is known as a leading edge due to its distinctive properties and outcomes was used in synthesizing Co-based powder on titanium alloy. The processing parameters used were laser power of 900W; scan speed of 0.6 to 1.2 m/min; powderfeedrate1.0g/min;beamspotsize3mm;gasflowrate1.2L/min.The effects of cobalt addition and laser parameters on corrosion behavior of laser clad Ti6AL4V coating in 0.5M sulfuric medium were investigated using linear potentiodynamic polarization. The changes in microstructure and corrosion behavior were analyzed using scanning electron microscopy (SEM) while the X –ray diffraction (XRD) indicates the intermetallics in the coatings. Results showed that the coatings displayed good metallurgical bonding with dendritic formations between the coatings and the substrate. The anodic current density increased with lower scan speed. However, the corrosion current densities of laser-clad samples were lower than Ti6Al4V alloy.

Effect of Cu addition on microstructure and corrosion behavior of spray-deposited Zn–30Al alloy

International Nuclear Information System (INIS)

Wang Feng; Xiong Baiqing; Zhang Yongan; Liu Hongwei; Li Zhihui; Li Xiwu; Qu Chu

2012-01-01

Highlights: ► Zn–30Al–xCu alloys were synthesized by the spray atomization and deposition technique. ► Immersion test and electrochemical measurements have been used to estimate the corrosion rate and the behavior. ► The result indicates that the 1 wt.% Cu addition displays superior corrosion resistance. - Abstract: In this study, one binary Zn–30Al and three ternary Zn–30Al–Cu alloys were synthesized by the spray atomization and deposition technique. The microstructures of the spray-deposited alloys were investigated by means of scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD). Immersion test, potentiodynamic polarization and electrochemical impedance measurements have been used to estimate the corrosion rate and the behavior. The results indicate that the 1 wt.% Cu addition to spray-deposited Zn–30Al alloy does not make significant change in microstructure. However, with the 2, 4 wt.% Cu additions to the alloy, some ε-CuZn 4 compounds with particle or irregular shapes were observed on the grain boundaries in the microstructures. Immersion test and electrochemical measurements confirmed that the 1 wt.% Cu addition displays superior corrosion resistance, whereas the 2, 4 wt.% Cu additions have a baneful effect on the corrosion behavior.

Corrosion behavior of boride layers evaluated by the EIS technique

Energy Technology Data Exchange (ETDEWEB)

Campos, I. [Instituto Politecnico Nacional. SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico)], E-mail: icampos@ipn.mx; Palomar-Pardave, M. [Universidad Autonoma Metropolitana-Azcapotzalco, Materials Department, Avenue San Pablo 180 Col. Reynosa Tamaulipas, Mexico D.F. 02200 (Mexico); Amador, A. [Tecnologico de Monterrey, Campus Ciudad de Mexico, Calle del Puente 222 Col. Ejidos de Huipulco, Mexico D.F. 14380 (Mexico); VillaVelazquez, C. [Instituto Politecnico Nacional. SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico); Hadad, J. [Tecnologico de Monterrey, Campus Ciudad de Mexico, Calle del Puente 222 Col. Ejidos de Huipulco, Mexico D.F. 14380 (Mexico)

2007-09-30

The corrosion behavior of boride layers at the AISI 304 steel surface is evaluated in the present study. Electrochemical impedance spectroscopy (EIS) technique was used for the evaluation of the polarization resistance at the steel surface, with the aid of AUTOLAB potentiostat. Samples were treated with boron paste thickness of 4 and 5 mm, in the range of temperatures 1123 {<=} T {<=} 1273 K and exposed time of 4 and 6 h. The electrochemical technique employed 10 mV AC with a frequency scan range from 8 kHz to 3 mHz in deaerated 0.1 M NaCl solution. Nyquist diagrams show that the highest values of corrosion resistance are present in the samples borided at the temperature of 1273 K, with treatment time of 4 h and 4 mm of boron paste thickness. The values of corrosion resistance on borided steels are compared with the porosity exhibited in the layers.

Effect of cold-rolling on pitting corrosion of 304 austenitic stainless steel

International Nuclear Information System (INIS)

Peguet, L.; Malki, B.; Baroux, B.

2004-01-01

Full text of publication follows: This paper deals with a not very often investigated topic on relation between cold-working and stainless steels localized corrosion resistance. It is devoted to the study of the cold-rolling effects on the pitting corrosion behavior of a 304 stainless steel grade in chloride containing aqueous electrolytes. It focus particularly on the analysis of metastable pitting transients observed at Open Circuit Potential using an experimental protocol including two identical working electrodes connected through a zero-impedance. As received the used specimens were heat-treated at 1100 C for 30 s and cold-rolled at 10%, 20%, 30% up to a final reduction pass of 70% inducing a large amount of α'-martensite. Then, current-potential fluctuations measurements were performed at OCP in NaCl 0.1 M + FeCl 3 2.10 -4 M containing aqueous solution during 24 h from the immersion time. As expected, a detrimental effect on corrosion behavior induced by cold rolling has been confirmed. Surprisingly, this is a nonlinear effect as a function of cold-rolling rate which controverts the hypothesis that strain induced martensite is the principal factor to explain this kind of sensibilizing. In particular, the results show a maximum of the metastable pits initiation frequency at 20% of cold-rolling rate. Moreover, the passive film/electrochemical double layer resistance and capacity deduced from the transients study show an analog nonlinear behavior. So, the transfer resistance show a minimum around 10-20% of cold-rolling rate where one can assume an increase of the electrons transfer kinetics through the interface. Conversely, the interfacial capacity is the highest at 20% of cold-rolling rate. Finally, It is expected a combined effect of the cold-rolled induced martensite and the dislocations arrangement via the mechano-chemical theory discussed by Gutman. (authors)

Potentiodynamic polarization study of the corrosion behavior of palladium-silver dental alloys.

Science.gov (United States)

Sun, Desheng; Brantley, William A; Frankel, Gerald S; Heshmati, Reza H; Johnston, William M

2018-04-01

Although palladium-silver alloys have been marketed for over 3 decades for metal-ceramic restorations, understanding of the corrosion behavior of current alloys is incomplete; this understanding is critical for evaluating biocompatibility and clinical performance. The purpose of this in vitro study was to characterize the corrosion behavior of 3 representative Pd-Ag alloys in simulated body fluid and oral environments and to compare them with a high-noble Au-Pd alloy. The study obtained values of important electrochemical corrosion parameters, with clinical relevance, for the rational selection of casting alloys. The room temperature in vitro corrosion characteristics of the 3 Pd-Ag alloys and the high-noble Au-Pd alloy were evaluated in 0.9% NaCl, 0.09% NaCl, and Fusayama solutions. After simulated porcelain firing heat treatment, 5 specimens of each alloy were immersed in the electrolytes for 24 hours. For each specimen, the open-circuit potential (OCP) was first recorded, and linear polarization was then performed from -20 mV to +20 mV (versus OCP) at a rate of 0.125 mV/s. Cyclic polarization was subsequently performed on 3 specimens of each alloy from -300 mV to +1000 mV and back to -300 mV (versus OCP) at a scanning rate of 1 mV/s. The differences in OCP and corrosion resistance parameters (zero-current potential and polarization resistance) among alloys and electrolyte combinations were compared with the 2-factor ANOVA (maximum-likelihood method) with post hoc Tukey adjustments (α=.05). The 24-hour OCPs and polarization resistance values of the 3 Pd-Ag alloys and the Au-Pd alloy were not significantly different (P=.233 and P=.211, respectively) for the same electrolyte, but significant differences were found for corrosion test results in different electrolytes (Palloy and electrolyte (P=.249 and P=.713, respectively). The 3 Pd-Ag silver alloys appeared to be resistant to chloride ion corrosion, and passivation and de-alloying were identified for these

Development of Advanced In-Situ Techniques for Chemistry Monitoring and Corrosion Mitigation in SCWO Environments

International Nuclear Information System (INIS)

Macdonald, D. D.; Lvov, S. N.

2000-01-01

This project is developing sensing technologies and corrosion monitoring techniques for use in super critical water oxidation (SCWO) systems to reduce the volume of mixed low-level nuclear waste by oxidizing organic components in a closed cycle system where CO2 and other gaseous oxides are produced, leaving the radioactive elements concentrated in ash. The technique uses water at supercritical temperatures under highly oxidized conditions by maintaining a high fugacity of molecular oxygen in the system, which causes high corrosion rates of even the most corrosive resistant reactor materials. This project significantly addresses the high corrosion shortcoming through development of (a) advanced electrodes and sensors for in situ potentiometric monitoring of pH in high subcritical and supercritical aqueous solutions, (b) an approach for evaluating the association constants for 1-1 aqueous electrolytes using a flow-through electrochemical thermocell; (c) an electrochemical noise sensor for the in situ measurement of corrosion rate in subcritical and supercritical aqueous systems; (d) a model for estimating the effect of pressure on reaction rates, including corrosion reactions, in high subcritical and supercritical aqueous systems. The project achieved all objectives, except for installing some of the sensors into a fully operating SCWO system

Development of Advanced In-Situ Techniques for Chemistry Monitoring and Corrosion Mitigation in SCWO Environments

Energy Technology Data Exchange (ETDEWEB)

Macdonald, D. D.; Lvov, S. N.

2000-03-31

This project is developing sensing technologies and corrosion monitoring techniques for use in super critical water oxidation (SCWO) systems to reduce the volume of mixed low-level nuclear waste by oxidizing organic components in a closed cycle system where CO2 and other gaseous oxides are produced, leaving the radioactive elements concentrated in ash. The technique uses water at supercritical temperatures under highly oxidized conditions by maintaining a high fugacity of molecular oxygen in the system, which causes high corrosion rates of even the most corrosive resistant reactor materials. This project significantly addresses the high corrosion shortcoming through development of (a) advanced electrodes and sensors for in situ potentiometric monitoring of pH in high subcritical and supercritical aqueous solutions, (b) an approach for evaluating the association constants for 1-1 aqueous electrolytes using a flow-through electrochemical thermocell; (c) an electrochemical noise sensor for the in situ measurement of corrosion rate in subcritical and supercritical aqueous systems; (d) a model for estimating the effect of pressure on reaction rates, including corrosion reactions, in high subcritical and supercritical aqueous systems. The project achieved all objectives, except for installing some of the sensors into a fully operating SCWO system.

Monitoring Cathodic Shielding and Corrosion under Disbonded Coatings

Energy Technology Data Exchange (ETDEWEB)

Varela, F.; Tan, M. Y. J.; Hinton, B.; Forsyth, M. [Deakin University, Victoria (Australia)

2017-06-15

Monitoring of corrosion is in most cases based on simulation of environmental conditions on a large and complex structure such as a buried pipeline using a small probe, and the measurement of thermodynamics and kinetics of corrosion processes occurring on the probe surface. This paper presents a hybrid corrosion monitoring probe designed for simulating deteriorating conditions wrought by disbonded coatings and for measuring current densities and distribution of such densities on a simulated pipeline surface. The concept of the probe was experimentally evaluated using immersion tests under cathodic protection (CP) in high resistivity aqueous solution. Underneath the disbonded area, anodic currents and cathodic currents were carefully measured. Anodic current densities were used to calculate metal loss according to Faraday’s law. Calculated corrosion patterns were compared with corrosion damage observed at the surface of the probe after a series of stringent tests. The capability of the probe to measure anodic current densities under CP, without requiring interruption, was demonstrated in high resistivity aqueous solution. The pattern of calculated metal loss correlated well with corrosion products distribution observed at the array surface. Working principles of the probe are explained in terms of electrochemistry.

Corrosion and passivation behavior of various stainless steels in libr solution used in absorption-type refrigeration system

International Nuclear Information System (INIS)

Shahid, M.

2007-01-01

Various structural materials have been suggested for the refrigeration units to combat high corrosiveness of the absorbent. The corrosion behavior of three grades of austenitic stainless steels, have been investigated in lithium bromide (LiBr) solutions, using electrochemical techniques. Potentiodynamic E- log-i curves, potential-time scans and polarization resistance diagrams obtained by using three-electrode system connected to a computerized Gamry at the rate framework, have been used to analyze their corrosion and passivation behavior in various concentrations of LiBr i.e. commercial LiBr (850 g/J solution containing chromate inhibitor), 400 g/l LiBr and 700 g/J LiBr solutions, at room temperature. Relatively higher corrosion current was observed in SS304 exposed to inhibitor-free electrolyte compared to inhibited commercial solution. Inhibitor proved to be more efficient in case of AISI 304 as it showed significantly higher corrosion rate in un-inhibited solutions. (author)

Effect of Nano-crystalline Ceramic Coats Produced by Plasma Electrolytic Oxidation on Corrosion Behavior of AA5083 Aluminum Alloy

International Nuclear Information System (INIS)

Thayananth, T.; Muthupandi, V.; Rao, S. R. Koteswara

2010-01-01

High specific strength offered by aluminum and magnesium alloys makes them desirable in modern transportation industries. Often the restrictions imposed on the usage of these alloys are due to their poor tribological and corrosion properties. However, their corrosion properties can be further enhanced by synthesizing ceramic coating on the substrate through Plasma Electrolytic Oxidation (PEO) process. In this study, nano-crystalline alumina coatings were formed on the surface of AA5083 aluminum alloy test coupons using PEO process in aqueous alkali-silicate electrolyte with and without addition of sodium aluminate. X-ray diffraction (XRD) studies showed that the crystallite size varied between 38 and 46 nm and α- and γ- alumina were the dominant phases present in the coatings. Corrosion studies by potentiodynamic polarization tests in 3.5% NaCl revealed that the electrolyte composition has an influence on the corrosion resistance of nano-crystalline oxide layer formed.

Effect of hydrogen on the corrosion behavior of the Mg–xZn alloys

Directory of Open Access Journals (Sweden)

Yingwei Song

2014-09-01

Full Text Available Hydrogen evolution reaction is inevitable during the corrosion of Mg alloys. The effect of hydrogen on the corrosion behavior of the Mg–2Zn and Mg–5Zn alloys is investigated by charging hydrogen treatment. The surface morphologies of the samples after charging hydrogen were observed using a scanning electron microscopy (SEM and the corrosion resistance was evaluated by polarization curves. It is found that there are oxide films formed on the surface of the charged hydrogen samples. The low hydrogen evolution rate is helpful to improve the corrosion resistance of Mg alloys, while the high hydrogen evolution rate can increases the defects in the films and further deteriorates their protection ability. Also, the charging hydrogen effect is greatly associated with the microstructure of Mg substrate.

Effect of Secondary Phase Precipitation on the Corrosion Behavior of Duplex Stainless Steels.

Science.gov (United States)

Chan, Kai Wang; Tjong, Sie Chin

2014-07-22

Duplex stainless steels (DSSs) with austenitic and ferritic phases have been increasingly used for many industrial applications due to their good mechanical properties and corrosion resistance in acidic, caustic and marine environments. However, DSSs are susceptible to intergranular, pitting and stress corrosion in corrosive environments due to the formation of secondary phases. Such phases are induced in DSSs during the fabrication, improper heat treatment, welding process and prolonged exposure to high temperatures during their service lives. These include the precipitation of sigma and chi phases at 700-900 °C and spinodal decomposition of ferritic grains into Cr-rich and Cr-poor phases at 350-550 °C, respectively. This article gives the state-of the-art review on the microstructural evolution of secondary phase formation and their effects on the corrosion behavior of DSSs.

Experimental measurements of U24Py nanocluster behavior in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Flynn, Shannon L.; Szymanowski, Jennifer E.S.; Fein, Jeremy B. [Univ. of Notre Dame, IN (United States). Department of Civil and Environmental Engineering and Earth Sciences; Dembowski, Mateusz [Univ. of Notre Dame, IN (United States). Department of Chemistry and Biochemistry; Burns, Peter C. [Univ. of Notre Dame, IN (United States). Department of Civil and Environmental Engineering and Earth Sciences; Univ. of Notre Dame, IN (United States). Department of Chemistry and Biochemistry

2016-07-01

Uranyl peroxide nanoclusters may impact the mobility and partitioning of uranium at contaminated sites and could be used in the isolation of uranium during the reprocessing of nuclear waste. Their behavior in aqueous systems must be better understood to predict the environmental fate of uranyl peroxide nanoclusters and for their use in engineered systems. The aqueous stability of only one uranyl peroxide nanocluster, U60 (K{sub 16}Li{sub 44}[UO{sub 2}(O{sub 2})OH]{sub 60}), has been studied to date [Flynn, S. L., Szymanowski, J. E. S., Gao, Y., Liu, T., Burns, P. C., Fein, J. B.: Experimental measurements of U60 nanocluster stability in aqueous solution. Geochemica et Cosmochimica Acta 156, 94-105 (2015)]. In this study, we measured the aqueous stability of a second uranyl peroxide nanocluster, U24Py (Na{sub 30}[(UO{sub 2}){sub 24}(O{sub 2}){sub 24}(HP{sub 2}O{sub 7}){sub 6}(H{sub 2}P{sub 2}O{sub 7}){sub 6}]), in batch systems as a function of time, pH, and nanocluster concentration, and then compared the aqueous behavior of U24Py to U60 to determine whether the size and morphology differences result in differences in their aqueous behaviors. Systems containing U24Py nanoclusters took over 30 days to achieve steady-state concentrations of monomeric U, Na, and P, illustrating slower reaction kinetics than parallel U60 systems. Furthermore, U24Py exhibited lower stability in solution than U60, with an average of 72% of the total mass in each nanocluster suspension being associated with the U24Py nanocluster, whereas 97% was associated with the U60 nanocluster in parallel experiments [Flynn, S. L., Szymanowski, J. E. S., Gao, Y., Liu, T., Burns, P. C., Fein, J. B.: Experimental measurements of U60 nanocluster stability in aqueous solution. Geochemica et Cosmochimica Acta 156, 94-105 (2015)]. The measurements from the batch experiments were used to calculate ion activity product (IAP) values for the reaction between the U24Py nanocluster and its constituent monomeric

Grain size effect in corrosion behavior of electrodeposited nanocrystalline Ni coatings in alkaline solution

International Nuclear Information System (INIS)

Wang Liping; Zhang Junyan; Gao Yan; Xue Qunji; Hu Litian; Xu Tao

2006-01-01

Effects of grain size reduction on the electrochemical corrosion behavior of nanocrystalline Ni produced by pulse electrodeposition were characterized using potentiodynamic polarization testing and electrochemical impedance spectroscopy; X-ray photoelectron spectroscopy were used to confirm the electrochemical measurements and the suggested mechanisms. The corrosion resistance of Ni coatings in alkaline solutions considerably increased as the grain size decreased from microcrystalline to nanocrystalline. The higher corrosion resistance of NC Ni may be due to the more rapid formation of continuous Ni(OH) 2 passive films compared with coarse-grained Ni coatings

Influence of processing variables and alloy chemistry on the corrosion behavior of ZIRLO nuclear fuel cladding

International Nuclear Information System (INIS)

Comstock, R.J.; Sabol, G.P.; Schoenberger, G.

1996-01-01

Variations in the thermal heat treatments used during the fabrication of ZIRLO (Zr-1Nb-1Sn-0.1Fe) fuel clad tubing and in ZIRLO alloy chemistry were explored to develop a further understanding of the relationship between processing, microstructure, and cladding corrosion performance. Heat treatment variables included intermediate tube annealing temperatures as well as a beta-phase heat treatment during the latter stages of the tube reduction schedule. Chemistry variables included deviations in niobium and tin content from the nominal composition. The effects of both heat treatment and chemistry on corrosion behavior were assessed by autoclave tests in both pure and lithiated water and high-temperature steam. Analytical electron microscopy demonstrated that the best out-reactor corrosion performance is obtained for microstructures containing a fine distribution of beta-niobium and Zr-Nb-Fe particles. Deviations from this microstructure, such as the presence of beta-zirconium phase, tend to degrade corrosion resistance. ZIRLO fuel cladding was irradiated in four commercial reactors. In all cases, the microstructure in the cladding included beta-niobium and Zr-Nb-Fe particles. ZIRLO fuel cladding processed with a late-stage beta heat treatment to further refine the second-phase particle size exhibited in-reactor corrosion behavior that was similar to reference ZIRLO cladding. Variations of the in-reactor corrosion behavior of ZIRLO were correlated to tin content, with higher oxide thickness observed in the ZIRLO cladding containing higher tin. The results of these studies indicate that optimum corrosion performance of ZIRLO is achieved by maintaining a uniform distribution of fine second-phase particles and controlled levels of tin

Dependence of Crystallographic Orientation on Pitting Corrosion Behavior of Ni-Fe-Cr Alloy 028

Science.gov (United States)

Zhang, LiNa; Szpunar, Jerzy A.; Dong, JianXin; Ojo, Olanrewaju A.; Wang, Xu

2018-03-01

The influence of crystallographic orientation on the pitting corrosion behavior of Ni-Fe-Cr alloy 028 was studied using a combination of X-ray diffraction (XRD), electron backscatter diffraction (EBSD), potentiodynamic polarization technique, and atomic force microscopy (AFM). The results show that there is anisotropy of pitting corrosion that strongly depends on crystallographic orientation of the surface plane. The distribution of pit density in a standard stereographic triangle indicates that the crystallographic planes close to {100} are more prone to pitting corrosion compared to planes {110} and {111}. The surface energy calculation of (001) and (111) shows that the plane with a high atomic packing density has a low surface energy with concomitant strong resistance to pitting corrosion. A correlation function between crystallographic orientation and pitting corrosion susceptibility suggests a method that not only predicts the pitting resistance of known textured materials, but also could help to improve corrosion resistance by controlling material texture.

Influence of sulfide concentration on the corrosion behavior of pure copper in synthetic seawater

International Nuclear Information System (INIS)

Taniguchi, Naoki; Kawasaki, Manabu

2008-01-01

Corrosion rate and stress corrosion cracking (SCC) behavior of pure copper under anaerobic conditions were studied by immersion tests and slow strain rate tests (SSRT) in synthetic seawater containing Na 2 S. The corrosion rate was increased with sulfide concentration both in simple saline solution and in bentnite-sand mixture. The results of SSRT showed that copper was susceptible to intergranular attack; selective dissolution at lower sulfide concentration (less than 0.005 M) and SCC at higher sulfide concentration (0.01 M). It was expected that if the sulfide concentration in groundwater is less than 0.001 M, pure copper is possible to exhibit superior corrosion resistance under anaerobic condition evident by very low corrosion rates and immunity to SCC. In such a low sulfide environment, copper overpack has the potential to achieve super-long lifetimes exceeding several tens of thousands years according to long-term simulations of corrosion based on diffusion of sulfide in buffer material

Corrosion Inhibitors for Aluminum.

Science.gov (United States)

Muller, Bodo

1995-01-01

Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

Corrosion behavior of porous chromium carbide in supercritical water

International Nuclear Information System (INIS)

Dong Ziqiang; Chen Weixing; Zheng Wenyue; Guzonas, Dave

2012-01-01

Highlights: ► Corrosion behavior of porous Cr 3 C 2 in various SCW conditions was investigated. ► Cr 3 C 2 is stable in SCW at temperature below 420–430 °C. ► Cracks and disintegration were observed at elevated testing temperatures. ► Degradation of Cr 3 C 2 is related to the intermediate product CrOOH. - Abstract: The corrosion behavior of highly porous chromium carbide (Cr 3 C 2 ) prepared by a reactive sintering process was characterized at temperatures ranging from 375 °C to 625 °C in a supercritical water environment with a pressure of 25–30 MPa. The test results show that porous chromium carbide is stable in SCW environments at temperatures under 425 °C, above which disintegration occurred. The porous carbide was also tested under hydrothermal conditions of pressures between 12 MPa and 50 MPa at constant temperatures of 400 °C and 415 °C, respectively. The pressure showed little effect on the stability of chromium carbide in the tests at those temperatures. The mechanism of disintegration of chromium carbide in SCW environments is discussed.

Effect of Mucin and Bicarbonate Ion on Corrosion Behavior of AZ31 Magnesium Alloy for Airway Stents.

Science.gov (United States)

Jang, Yongseok; Owuor, Daniel; Waterman, Jenora T; White, Leon; Collins, Boyce; Sankar, Jagannathan; Gilbert, Thomas W; Yun, Yeoheung

2014-08-15

The biodegradable ability of magnesium alloys is an attractive feature for tracheal stents since they can be absorbed by the body through gradual degradation after healing of the airway structure, which can reduce the risk of inflammation caused by long-term implantation and prevent the repetitive surgery for removal of existing stent. In this study, the effects of bicarbonate ion (HCO₃ - ) and mucin in Gamble's solution on the corrosion behavior of AZ31 magnesium alloy were investigated, using immersion and electrochemical tests to systematically identify the biodegradation kinetics of magnesium alloy under in vitro environment, mimicking the epithelial mucus surfaces in a trachea for development of biodegradable airway stents. Analysis of corrosion products after immersion test was performed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS) was used to identify the effects of bicarbonate ions and mucin on the corrosion behavior of AZ31 magnesium alloys with the temporal change of corrosion resistance. The results show that the increase of the bicarbonate ions in Gamble's solution accelerates the dissolution of AZ31 magnesium alloy, while the addition of mucin retards the corrosion. The experimental data in this work is intended to be used as foundational knowledge to predict the corrosion behavior of AZ31 magnesium alloy in the airway environment while providing degradation information for future in vivo studies.

Corrosion behavior of novel imitation-gold copper alloy with rare earth in 3.5% NaCl solution

International Nuclear Information System (INIS)

Chen, J.L.; Li, Z.; Zhu, A.Y.; Luo, L.Y.; Liang, J.

2012-01-01

Highlights: → The design alloy has better anti-tarnish property than that of H7211 alloy during salt-spray test. → The corrosion rate of design alloy is much lower than that of H7211 alloy as immersed in NaCl solution. → In the low frequency region, the capacitive behavior normally faded and diffusion process had a key role. → In the medium frequency region, the Bode pattern showed a capacitive behavior. -- Abstract: A novel imitation-gold copper alloy with rare earth was designed and prepared. The corrosion behavior of the alloy immersed in 3.5% NaCl solution and its anti-tarnish property in the salt spray for different days has been studied. The designed alloy (CuZnAlNiMeRe) has more excellent anti-tarnish property and lower corrosion rate than those of currency coinage materials of H7211 alloy (used in China). A uniform and compact of corrosion film has been formed after the designed alloy immersed in 3.5% NaCl solution. The corrosion current densities I corr of the alloy decreased while the polarization resistance R p increased with time. The capacitance of the corrosion product film C film of the alloy decreased while the charge transfer resistance R ct . The Warburg diffusion impedance W R and the resistance of the equivalent circuit R increased with time.

States and transport of hydrogen in the corrosion process of an AZ91 magnesium alloy in aqueous solution

International Nuclear Information System (INIS)

Chen Jian; Wang Jianqiu; Han Enhou; Dong Junhua; Ke Wei

2008-01-01

Mott-Schottky measurement and secondary ion mass spectroscopy (SIMS) were used to investigate the states and transport of hydrogen during the corrosion behavior of an AZ91 magnesium alloy in 0.1 M sodium sulfate solution. The results showed that when samples were immersed or charged in solution, hydrogen atoms diffused into the film and reacted with vacancy to cause the increases of the carrier concentration (excess electron or hole carrier) and diffusion rate of hydrogen. Some hydrogen atoms diffused to interior of matrix and enriched in β phase while others resorted in the corrosive film. With the increase of immersion or charging time, magnesium hydride would be brittle fractured when the inner stress caused by hydrogen pressure and expansion stress of formation of magnesium hydride was above the fracture strength, which provided the direct experimental evidence of the hydrogen embrittlement (HE) mechanism of magnesium and its alloys. After immersion in solution, the transfer of excess electrons to the interfaces of corrosion film and solution would destroy the charge equilibrium in the film and stimulate the adsorption of SO 4 2- , which resulted in the initiation of localized corrosion; after cathodic charging and then immersion, the enrichment of hydrogen atoms at interior of corrosion film would combine into hydrogen gas to form high pressure and result in the rupture of corrosion film, and localized corrosion initiated and developed at surface. Therefore, localized corrosion nucleated earlier on the charged samples than on the uncharged samples. Hydrogen invasion accelerated the corrosion of matrix

Effect of aging time on intergranular corrosion behavior of a newly developed LDX 2404 lean duplex stainless steel

Energy Technology Data Exchange (ETDEWEB)

Zhao, Hui [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zhang, Ziying, E-mail: zzying@sues.edu.cn [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zhang, Huizhen [School of Management, University of Shanghai for Science and Technology, Shanghai 200093 (China); Hu, Jun [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Li, Jin [Department of Materials Science, Fudan University, Shanghai 200433 (China)

2016-07-05

The effect of aging at 700 °C for various times on the intergranular corrosion behavior of LDX 2404 duplex stainless steel is investigated by morphological observation and electrochemical detection. Scanning electronic microscopy and transmission electronic microscopy analysis reveal that Cr{sub 2}N, M{sub 23}C{sub 6} and the sigma and chi phases nucleate simultaneously at the initial stages of aging. The granular particles of sigma phase grow larger but fewer with the increase of aging time. The electrochemical detection results show that intergranular corrosion become more severe and the corrosion type evolves from intergranular corrosion into general corrosion as the holding time extends to 48 h. - Highlights: • The IGC behavior of aged LDX 2404 is investigated. • Cr{sub 2}N, M{sub 23}C{sub 6} and the σ and χ phases nucleate simultaneously at the initial stages of aging. • IGC resistance decreases with the increase of aging time. • The corrosion type evolves from IGC into general corrosion for longer aging times.

Corrosion inhibition behavior of Ketosulfone for Zinc in acidic medium

African Journals Online (AJOL)

The corrosion inhibition behavior of Ketosulfone for zinc is investigated by polarization and AC-impedance techniques at 303-333K. The Tafel plots indicates that the Ketosulfone is a mixed type inhibitor. The interaction between metal and inhibitor is explained by Langmuir adsorption isotherm. DG0ads andDH0ads value ...

Corrosion behavior of materials selected for FMIT lithium system

Energy Technology Data Exchange (ETDEWEB)

Bazinet, G.D.; Down, M.G.; Matlock, D.K.

1983-01-01

The corrosion program consisted of a multi-disciplinary approach utilizing the liquid lithium test resources and capabilities of several laboratories. Specific concerns associated with the overall objective of materials corrosion behavior were evaluated at each laboratory. Testing conditions included: approx. 3700 hours of exposure to flowing lithium at temperatures from 230/sup 0/C to 270/sup 0/C and approx. 6500 hours of exposure to flowing lithium at an isothermal temperature of 270/sup 0/C. Principal areas of investigation, to be discussed here briefly, included lithium corrosion effects on the following: (1) types 304 and 304L austenitic stainless steels, which are specified as reference materials for the FMIT lithium system; (2) type 304 stainless steel weldments (w/type 308 stainless steel filler) typical of specified tube and butt welds in the lithium system design; (3) titanium, zirconium and yttrium, which represent potential hot trap getter materials; (4) BNi4 braze alloy, used as a potential attachement method in the plug/seat fabrication of liquid lithium valves; and (5) type 321 stainless steel bellows, typical of bellows used in potential liquid lithium valve designs.

Investigation of high temperature corrosion behavior on 304L austenite stainless steel in corrosive environments

Energy Technology Data Exchange (ETDEWEB)

Sahri, M. I.; Othman, N. K.; Samsu, Z.; Daud, A. R. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor (Malaysia)

2014-09-03

In this work, 304L stainless steel samples were exposed at 700 °C for 10hrs in different corrosive environments; dry oxygen, molten salt, and molten salt + dry oxygen. The corrosion behavior of samples was analyzed using weight change measurement technique, optical microscope (OM) and Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray (EDX). The existence phases of corroded sample were determined using X-ray Diffraction (XRD). The lowest corrosion rate was recorded in dry oxygen while the highest was in molten salt + dry oxygen environments with the value of 0.0062 mg/cm{sup 2} and −13.5225 mg/cm{sup 2} respectively. The surface morphology of sample in presence of salt mixture showed scale spallation. Oxide scales of Fe{sub 3}O{sub 4}, Fe{sub 2}O{sub 3} were the main phases developed and detected by XRD technique. Cr{sub 2}O{sub 3} was not developed in every sample as protective layers but chromate-rich oxide was developed. The cross-section analysis found the oxide scales were in porous, thick and non-adherent that would not an effective barrier to prevent from further degradation of alloy. EDX analysis also showed the Cr-element was low compared to Fe-element at the oxide scale region.

Evaluating the effects of hydroxyapatite coating on the corrosion behavior of severely deformed 316Ti SS for surgical implants

International Nuclear Information System (INIS)

Mhaede, Mansour; Ahmed, Aymen; Wollmann, Manfred; Wagner, Lothar

2015-01-01

The present work investigates the effects of severe plastic deformation by cold rolling on the microstructure, the mechanical properties and the corrosion behavior of austenitic stainless steel (SS) 316Ti. Hydroxyapatite coating (HA) was applied on the deformed material to improve their corrosion resistance. The martensitic transformation due to cold rolling was recorded by X-ray diffraction spectra. The effects of cold rolling on the corrosion behavior were studied using potentiodynamic polarization. The electrochemical tests were carried out in Ringer's solution at 37 ± 1 °C. Cold rolling markedly enhanced the mechanical properties while the electrochemical tests referred to a lower corrosion resistance of the deformed material. The best combination of both high strength and good corrosion resistance was achieved after applying hydroxyapatite coating. - Highlights: • Cold rolling markedly increases the hardness of SS 316Ti from 125 to 460 HV10. • Higher deformation degrees lead to lower corrosion resistance. • Application of HA-coating leads to significant improvement of the corrosion resistance

Effect of H2O2 on the corrosion behavior of 304L stainless steel

International Nuclear Information System (INIS)

Song, Taek Hoh; Kim, In Sub; Noh, Sung Kee

1995-01-01

In connection with the safe storage of high level nuclear waste, effect of H 2 O 2 on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H 2 O 2 . The experimental results show that H 2 O 2 increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H 2 O 2 concentration increased, indicating that pitting resistance was decreased by the existence of H 2 O 2 in the electrolyte. These effects of H 2 O 2 on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H 2 O 2 with those of O 2 , cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H 2 O 2 on the corrosion behavior were very similar to those of O 2 such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. In acid and alkaline media, the corrosion potential shifts by H 2 O 2 were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively. 13 figs., 1 tabs., 17 refs. (Author)

The Corrosion Behavior of Nickel and Inconel 600 in Sodium Hydroxide and Hydrochloric Acid Solution at 280 .deg. C

International Nuclear Information System (INIS)

Lee, Ihh Chong; Suk, Tae Won

1980-01-01

The corrosion behavior of nickel and Inconel 600 has been investigated by the weight change measurement method at pH ranges 3∼13 of the solution. The specimens were exposed to aqueous solutions in a static autoclave at 280 .deg. C for 210 hours. The pH of the solutions was adjusted by hydrochloric acid and sodium hydroxide and the dissolved oxygen concentration was fixed as 10 ppb by using pure nitrogen gas. Weight loss of Inconel 600 was much less than that of nickel over the tested pH ranges. At pH 9.5, nickel and Inconel 600 showed the minimum weight loss phenomenon and the values of weight loss were 1.5mg/dm 2 and 0.9mg/dm 2 , respectively. Microscopic examination showed that nickel surface was attacked uniformly, whereas Inconel 600 surface was not greatly

Hot corrosion behavior of magnesia-stabilized ceramic material in a lithium molten salt

Energy Technology Data Exchange (ETDEWEB)

Cho, Soo-Haeng, E-mail: nshcho1@kaeri.re.kr [Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Kim, Sung-Wook [Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Kim, Dae-Young [Graduate School of Energy Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Lee, Jong-Hyeon, E-mail: jonglee@cnu.ac.kr [Graduate School of Energy Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Graduate School of Advanced Materials Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Rapidly Solidified Materials Research Center, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Hur, Jin-Mok [Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of)

2017-07-15

The isothermal and cyclic corrosion behaviors of magnesia-stabilized zirconia in a LiCl-Li{sub 2}O molten salt were investigated at 650 °C in an argon atmosphere. The weights of as-received and corroded specimens were measured and the microstructures, morphologies, and chemical compositions were analyzed by scanning electron microscopy, X-ray energy dispersive spectroscopy, and X-ray diffraction. For processes where Li is formed at the cathode during electrolysis, the corrosion rate was about five times higher than those of isothermal and thermal cycling processes. During isothermal tests, the corrosion product Li{sub 2}ZrO{sub 3} was formed after 216 h. During thermal cycling, Li{sub 2}ZrO{sub 3} was not detected until after the completion of 14 cycles. There was no evidence of cracks, pores, or spallation on the corroded surfaces, except when Li was formed. We demonstrate that magnesia-stabilized zirconia is beneficial for increasing the hot corrosion resistance of structural materials subjected to high temperature molten salts containing Li{sub 2}O. - Highlights: •Corrosion mechanism of MSZin LiCl-Li{sub 2}O molten salt is proposed. •Formation of Li{sub 2}ZrO{sub 3}is main corrosion mechanism. •There were no cracks, pores and spallation after corrosion test. •MSZ shows high corrosion resistance to LiCl-Li{sub 2}O molten salt.

Effect of ion implantation on the corrosion behavior of lead and a lead-antimony alloy

International Nuclear Information System (INIS)

Zhang, S.T.; Kong, F.P.; Muller, R.H.

1994-01-01

Ion implantation of different metals in Pb and Pb-4% Sb has been found to improve the open-circuit corrosion resistance of the two metals in 5M H 2 SO 4 . Titanium ions were implanted under different conditions of ion dose and ion energy. Optimum implantation conditions resulted in an up to 72-fold reduction of corrosion currents. The implantation of V, Cr, Ni, and W has been investigated for one implantation condition and has also resulted in decreased corrosion currents. The corrosion behavior was characterized by the current response to small anodic potential steps. Surface analysis and depth profiles have shown the importance of the spatial distribution of the implanted ions for their effects on the anodic and cathodic parts of the corrosion reactions

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

The control of the corrosion phenomenon is of prime importance for the nuclear industry. The efficiency and the safety of facilities can be affected by this phenomenon. The nuclear industry has to face corrosion for a large variety of materials submitted to various environments. Metallic corrosion operates in the hot and aqueous environment of water reactors which represent the most common reactor type in the world. Progresses made in the control of the corrosion of the different components of these reactors allow to improve their safety. Corrosion is present in the facilities of the back-end of the fuel cycle as well (corrosion in acid environment in fuel reprocessing plants, corrosion of waste containers in disposal and storage facilities, etc). The future nuclear systems will widen even more the range of materials to be studied and the situations in which they will be placed (corrosion by liquid metals or by helium impurities). Very often, corrosion looks like a patchwork of particular cases in its description. The encountered corrosion problems and their study are presented in this book according to chapters representing the main sectors of the nuclear industry and classified with respect to their phenomenology. This monograph illustrates the researches in progress and presents some results of particular importance obtained recently. Content: 1 - Introduction: context, stakes and goals; definition of corrosion; a complex science; corrosion in the nuclear industry; 2 - corrosion in water reactors - phenomenology, mechanisms, remedies: A - uniform corrosion: mechanisms, uniform corrosion of fuel cladding, in-situ measurement of generalized corrosion rate by electrochemical methods, uniform corrosion of nickel alloys, characterization of the passive layer and growth mechanisms, the PACTOLE code - an integrating tool, influence of water chemistry on corrosion and contamination, radiolysis impact on uniform corrosion; B - stress corrosion: stress corrosion cracking

Influence of the microstructure on the corrosion behavior of magnetron sputter-quenched amorphous metallic alloys

Science.gov (United States)

Thakoor, A. P.; Khanna, S. K.; Williams, R. M.; Landel, R. F.

1983-01-01

The microstructure and corrosion behavior of magnetron sputter deposited amorphous metallic films of (Mo6ORu40)82B18 under varying sputtering atmospheres have been investigated. The microstructural details and topology of the films have been studied by scanning electron microscopy and correlated with the deposition conditions. By reducing the pressure of pure argon gas, the characteristic features of rough surface and columnar growth full of vertical voids can be converted into a mirror-smooth finish with very dense deposits. Films deposited in the presence of O2 or N2 exhibit columnar structure with vertical voids. Film deposited in pure argon at low pressure show remarkably high corrosion resistance due to the formation of a uniform passive surface layer. The influence of the microstructure and surface texture on the corrosion behavior is discussed.

Relationships between chemical compositions, microstructure, and corrosion properties in molybdenum ion implanted aluminum

International Nuclear Information System (INIS)

Kim, S.

1986-01-01

This thesis compares the corrosion properties of Al annealed after implantation with selected Mo concentrations to those of as-implanted Al with same Mo level and to pure Al. The principal results in this investigation are the improvement in the pitting corrosion resistance for Al implanted with Mo relative to pure Al in both the as-implanted and as-implanted-annealed state. The corrosion properties were related to the microstructures and chemical profiles in the surface-modified-regions. Potentiodynamic measurements indicate that stability of various species on the surface controls corrosion behavior in the Al-Mo system. Dual energy Mo implant procedure was used to produce a relatively thick ion implanted layer. The processing parameters were selected to produce specimen containing a continuous Al 12 Mo film with two different microstructures in the annealed material. The most improved pitting corrosion resistance was achieved in an as-implanted alloy which was implanted at 95 keV and then at 25 keV. This alloy was very resistant to pitting corrosion in a neutral aqueous solution containing 0.1 M chloride ion. Surface chemical analysis by Auger electron spectroscopy indicates that the role of Mo in inhibiting pitting corrosion is related to the formation of stable Mo oxide film

Effect of Secondary Phase Precipitation on the Corrosion Behavior of Duplex Stainless Steels

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Kai Wang Chan

2014-07-01

Full Text Available Duplex stainless steels (DSSs with austenitic and ferritic phases have been increasingly used for many industrial applications due to their good mechanical properties and corrosion resistance in acidic, caustic and marine environments. However, DSSs are susceptible to intergranular, pitting and stress corrosion in corrosive environments due to the formation of secondary phases. Such phases are induced in DSSs during the fabrication, improper heat treatment, welding process and prolonged exposure to high temperatures during their service lives. These include the precipitation of sigma and chi phases at 700–900 °C and spinodal decomposition of ferritic grains into Cr-rich and Cr-poor phases at 350–550 °C, respectively. This article gives the state-of the-art review on the microstructural evolution of secondary phase formation and their effects on the corrosion behavior of DSSs.

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

Science.gov (United States)

Pech-Canul, M. A.; Guía-Tello, J. C.; Pech-Canul, M. I.; Aguilar, J. C.; Gorocica-Díaz, J. A.; Arana-Guillén, R.; Puch-Bleis, J.

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.

Effects of annealing on the corrosion behavior and mechanical properties of Ti-Al-V alloy

International Nuclear Information System (INIS)

Kim, T. K.; Choi, B. S.; Baek, J. H.; Choi, B. K.; Jeong, Y. H.; Lee, D. J.; Jang, M. H.; Jeong, Y. H.

2002-01-01

In order to determine the annealing condition after cold rolling, the effects of annealing on the corrosion behavior and mechanical properties of Ti-Al-V alloy were evaluated. The results of tensile tests at room temperature showed that the strengths and the ductility were almost independent of the annealing temperature. The results of hardness test also revealed that the hardness was independent of the annealing, However, the results of corrosion test in an ammoniated water of pH 9.98 at 360 .deg. C showed that the corrosion resistance depended on the annealing temperature, and the corrosion rate was accelerated with increasing annealing temperature. Hydrogen contents absorbed during the corrosion test of 120 days also increased with the annealing temperature. It may be attributed to the growth of α' precipitates by annealing. It is thus suggested that the lower annealing temperatures provide the better corrosion properties without degrading the tensile properties

Evaluation of steam corrosion and water quenching behavior of zirconium-silicide coated LWR fuel claddings

Science.gov (United States)

Yeom, Hwasung; Lockhart, Cody; Mariani, Robert; Xu, Peng; Corradini, Michael; Sridharan, Kumar

2018-02-01

This study investigates steam corrosion of bulk ZrSi2, pure Si, and zirconium-silicide coatings as well as water quenching behavior of ZrSi2 coatings to evaluate its feasibility as a potential accident-tolerant fuel cladding coating material in light water nuclear reactor. The ZrSi2 coating and Zr2Si-ZrSi2 coating were deposited on Zircaloy-4 flats, SiC flats, and cylindrical Zircaloy-4 rodlets using magnetron sputter deposition. Bulk ZrSi2 and pure Si samples showed weight loss after the corrosion test in pure steam at 400 °C and 10.3 MPa for 72 h. Silicon depletion on the ZrSi2 surface during the steam test was related to the surface recession observed in the silicon samples. ZrSi2 coating (∼3.9 μm) pre-oxidized in 700 °C air prevented substrate oxidation but thin porous ZrO2 formed on the coating. The only condition which achieved complete silicon immobilization in the oxide scale in aqueous environments was the formation of ZrSiO4 via ZrSi2 coating oxidation in 1400 °C air. In addition, ZrSi2 coatings were beneficial in enhancing quenching heat transfer - the minimum film boiling temperature increased by 6-8% in the three different environmental conditions tested. During repeated thermal cycles (water quenching from 700 °C to 85 °C for 20 s) performed as a part of quench tests, no spallation and cracking was observed and the coating prevented oxidation of the underlying Zircaloy-4 substrate.

Hydrogen assisted cracking and CO2 corrosion behaviors of low-alloy steel with high strength used for armor layer of flexible pipe

Science.gov (United States)

Liu, Zhenguang; Gao, Xiuhua; Du, Linxiu; Li, Jianping; Zhou, Xiaowei; Wang, Xiaonan; Wang, Yuxin; Liu, Chuan; Xu, Guoxiang; Misra, R. D. K.

2018-05-01

In this study, hydrogen induced cracking (HIC), sulfide stress corrosion cracking (SSCC) and hydrogen embrittlement (HE) were carried out to study hydrogen assisted cracking behavior (HIC, SSCC and HE) of high strength pipeline steel used for armor layer of flexible pipe in ocean. The CO2 corrosion behavior of designed steel with high strength was studied by using immersion experiment. The experimental results demonstrate that the corrosion resistance of designed steel with tempered martensite to HIC, SSCC and HE is excellent according to specific standards, which contributes to the low concentration of dislocation and vacancies previously formed in cold rolling process. The corrosion mechanism of hydrogen induced cracking of designed steel, which involves in producing process, microstructure and cracking behavior, is proposed. The designed steel with tempered martensite shows excellent corrosion resistance to CO2 corrosion. Cr-rich compound was first formed on the coupon surface exposed to CO2-saturated brine condition and chlorine, one of the corrosion ions in solution, was rich in the inner layer of corrosion products.

Corrosion behavior of biodegradable material AZ31 coated with beeswax-colophony resin

Science.gov (United States)

Gumelar, Muhammad Dikdik; Putri, Nur Ajrina; Anggaravidya, Mahendra; Anawati, Anawati

2018-05-01

Magnesium (Mg) and its alloys are potential candidates for biodegradable implant materials owing to their ability to degrade spontaneously in a physiological environment. However, the degradation rate is still considered too fast in human body solution. A coating is typically applied to slowdown corrosion rate of Mg alloys. In this work, an organic coating of mixture beeswax-colophony with ratios of 40-60, 50-50, and 60-40 in wt% was synthesized and applied on commercial magnesium alloyAZ31. The coated specimens were then characterized with SEM and XRF. The corrosion behavior of the coated specimens was evaluated by immersion test in 0.9 wt% NaCl solution at 37°C for 14 days. The results indicated that the coating material improved the corrosion resistance of the AZ31 alloy.

Study of Rust Effect on the Corrosion Behavior of Reinforcement Steel Using Impedance Spectroscopy

Science.gov (United States)

Bensabra, Hakim; Azzouz, Noureddine

2013-12-01

Most studies on corrosion of steel reinforcement in concrete are conducted on steel samples with polished surface (free of all oxides) in order to reproduce the same experimental conditions. However, before embedding in concrete, the steel bars are often covered with natural oxides (rust), which are formed during exposure to the atmosphere. The presence of this rust may affect the electrochemical behavior of steel rebar in concrete. In order to understand the effect of rust on the corrosion behavior of reinforcement steel, potentiodynamic and electrochemical impedance spectroscopy (EIS) tests were carried out in a simulated concrete pore solution using steel samples with two different surface conditions: polished and rusted samples. The obtained results have shown that the presence of rust on the steel bar has a negative effect on its corrosion behavior, with or without the presence of chlorides. This detrimental effect can be explained by the fact that the rust provokes a decrease of the electrolyte resistance at the metal-concrete interface and reduces the repassivating ability. In addition, the rust layer acts as a barrier against the hydroxyl ion diffusion, which prevents the realkalinization phenomenon.

Effect of magnesium hydride on the corrosion behavior of an AZ91 magnesium alloy in sodium chloride solution

International Nuclear Information System (INIS)

Chen Jian; Dong Junhua; Wang Jianqiu; Han Enhou; Ke Wei

2008-01-01

The effect of magnesium hydride on the corrosion behavior of an as-cast AZ91 alloy in 3.5 wt.% NaCl solution was investigated using gas collection method and potentiostatic test. The Pourbaix diagram of Mg-H 2 O system was built using thermodynamic calculation. It was possible that magnesium hydride could form in the whole pH range in theory. The experimental results showed that at cathodic region, magnesium hydride formed on surface, which was the controlling process for the corrosion behavior of AZ91 alloy; at anodic region and free corrosion potential, magnesium hydride model and partially protective film model, monovalent magnesium ion model and particle undermining model were responsible for the corrosion process of AZ91 alloy

Effect of Mucin and Bicarbonate Ion on Corrosion Behavior of AZ31 Magnesium Alloy for Airway Stents

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Yongseok Jang

2014-08-01

Full Text Available The biodegradable ability of magnesium alloys is an attractive feature for tracheal stents since they can be absorbed by the body through gradual degradation after healing of the airway structure, which can reduce the risk of inflammation caused by long-term implantation and prevent the repetitive surgery for removal of existing stent. In this study, the effects of bicarbonate ion (HCO3− and mucin in Gamble’s solution on the corrosion behavior of AZ31 magnesium alloy were investigated, using immersion and electrochemical tests to systematically identify the biodegradation kinetics of magnesium alloy under in vitro environment, mimicking the epithelial mucus surfaces in a trachea for development of biodegradable airway stents. Analysis of corrosion products after immersion test was performed using scanning electron microscopy (SEM, energy dispersive X-ray spectroscopy (EDX and X-ray diffraction (XRD. Electrochemical impedance spectroscopy (EIS was used to identify the effects of bicarbonate ions and mucin on the corrosion behavior of AZ31 magnesium alloys with the temporal change of corrosion resistance. The results show that the increase of the bicarbonate ions in Gamble’s solution accelerates the dissolution of AZ31 magnesium alloy, while the addition of mucin retards the corrosion. The experimental data in this work is intended to be used as foundational knowledge to predict the corrosion behavior of AZ31 magnesium alloy in the airway environment while providing degradation information for future in vivo studies.

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.

Studies on the Corrosion Behavior of TiCode-12 with the Variation of Environmental Factors and Heat Treatment Conditions

International Nuclear Information System (INIS)

Yoon, S. R.; Kim, T. Y.; Lee, K. H.

1989-01-01

Corrosion behavior of TiCode-12 (Ti-0.8Ni-0.3Mo) has been studied by means of electrochemical polarization measurements and corrosion morphology examinations in various corrosive environments and different heat treatment conditions of the alloy. 1N H 2 SO 4 at 45 .deg. C was taken as a standard corrosive solution in which Cl - , Fe 3+ and Br - ion were added to investigate their effects. Acid concentration and temperature were also varied. Polarization behaviors of pure Ti, Ni, Mo and Ti 2 Ni were compared with those of heat-treated TiCode-12 specimens to find out how the constituent elements and the intermetallic compound formed during heat treatment of TiCode-12 affect the corrosion of the alloy. Mill-annealed TiCode-12 showed primary and secondary active-passive transition behavior in all the tested H 2 SO 4 solutions. The former behavior was confirmed to be due to Ti and the latter due to Ni and Mo. The passive current densities increased with increased Cl - ion concentration but decreased reversely beyond certain concentration. Fe 3+ ion raised the corrosion potential of TiCode-12 to the passive region, thus reducing the corrosion rate. Br - ion was turned out to be a critical species to induce the pitting of TiCode-12 by some unknown reason. Cathodic polarization behavior of pure Ni and Ti 2 Ni revealed that hydrogen evolution reaction was promoted on these electrodes in acid media. This was ascribed to the cause for sensitization phenomena of TiCode-12 heat-treated in the temperature range in which the eutectoid reaction β→α + Ti 2 Ni occurs. Near pits, observed on a sensitized TiCode-12 specimen immersed in H 2 SO 4 , always found were β crystals in which Ni peak was detected by EDS

The Behavior of Environmentally Friendly Corrosion Preventative Compounds in an Aggressive Coastal Marine Environment

Science.gov (United States)

Montgomery, Eliza L.; Calle, Luz Marina; Curran Jerome C.; Kolody, Mark R.

2013-01-01

The shift to use environmentally friendly technologies throughout future space-related launch programs prompted a study aimed at replacing current petroleum and solvent-based Corrosion Preventive Compounds (CPCs) with environmentally friendly alternatives. The work in this paper focused on the identification and evaluation of environmentally friendly CPCs for use in protecting flight hardware and ground support equipment from atmospheric corrosion. The CPCs, while a temporary protective coating, must survive in the aggressive coastal marine environment that exists throughout the Kennedy Space Center, Florida. The different protection behaviors of fifteen different soft film CPCs, both common petroleum-based and newer environmentally friendly types, were evaluated on various steel and aluminum substrates. The CPC and substrate systems were subjected to atmospheric testing at the Kennedy Space Center's Beachside Atmospheric Corrosion Test Site, as well as cyclic accelerated corrosion testing. Each CPC also underwent physical characterization and launch-related compatibility testing . The initial results for the fifteen CPC systems are reported : Key words: corrosion preventive compound, CPC, spaceport, environmentally friendly, atmospheric exposure, marine, carbon steel, aluminum alloy, galvanic corrosion, wire on bolt.

Elastic and plastic strains and the stress corrosion cracking of austenitic stainless steels. Final report

International Nuclear Information System (INIS)

Vaccaro, F.P.; Hehemann, R.F.; Troiano, A.R.

1979-08-01

The influence of elastic (stress) and plastic (cold work) strains on the stress corrosion cracking of a transformable austenitic stainless steel was studied in several aqueous chloride environments. Initial polarization behavior was active for all deformation conditions as well as for the annealed state. Visual observation, potential-time, and current-time curves indicated the development of a pseudo-passive (flawed) film leading to localized corrosion, occluded cells and SCC. SCC did not initiate during active corrosion regardless of the state of strain unless severe low temperature deformation produced a high percentage of martensite. Both elastic and plastic deformation increased the sensitivity to SCC when examined on the basis of percent yield strength. The corrosion potential, the critical cracking potential, and the potential at which the current changes from anodic to cathodic were essentially unaffected by deformation. It is apparent that the basic electrochemical parameters are independent of the bulk properties of the alloy and totally controlled by surface phenomena

Multilayered Zn-Ni alloy coatings for better corrosion protection of mild steel

Directory of Open Access Journals (Sweden)

Sadananda Rashmi

2017-06-01

Full Text Available A simple aqueous electrolyte for the deposition of anti-corrosive Zn-Ni alloy coatings was optimized using conventional Hull cell method. The corrosion protection value of the electrodeposited coatings at a current density (c.d. range of 2.0–5.0 A dm−2 has been testified in 5 wt% NaCl solution, as representative corrosion medium. The electrochemical behavior of the coatings towards corrosion was related to its surface topography, elemental composition and phase structure using scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS and X-ray diffraction (XRD analyses, respectively. Among the monolithic coatings developed at different c.d.’s, the coating obtained at 3.0 A dm−2 was found to be the best with least corrosion current (icorr value. Further, the corrosion protection efficacy of the monolayer coatings were improved to many folds through multilayer coating approach, by modulating the cyclic cathode current densities (CCCD’s. The composition modulated multilayer (CMM Zn-Ni alloy coating with 60 layers, developed from the combination of CCCD’s 3.0 and 5.0 A dm−2 was found to be the best with 3 fold enhancement in corrosion protection efficiency. The formation of multilayer coatings was confirmed using cross-sectional SEM, and the experimental results are discussed with tables and figures.

Corrosion behavior of 2205 duplex stainless steel.

Science.gov (United States)

Platt, J A; Guzman, A; Zuccari, A; Thornburg, D W; Rhodes, B F; Oshida, Y; Moore, B K

1997-07-01

The corrosion of 2205 duplex stainless steel was compared with that of AISI type 316L stainless steel. The 2205 stainless steel is a potential orthodontic bracket material with low nickel content (4 to 6 wt%), whereas the 316L stainless steel (nickel content: 10 to 14 wt%) is a currently used bracket material. Both stainless steels were subjected to electrochemical and immersion (crevice) corrosion tests in 37 degrees C, 0.9 wt% sodium chloride solution. Electrochemical testing indicates that 2205 has a longer passivation range than 316L. The corrosion rate of 2205 was 0.416 MPY (milli-inch per year), whereas 316L exhibited 0.647 MPY. When 2205 was coupled to 316L with equal surface area ratio, the corrosion rate of 2205 reduced to 0.260 MPY, indicating that 316L stainless steel behaved like a sacrificial anode. When 316L is coupled with NiTi, TMA, or stainless steel arch wire and was subjected to the immersion corrosion test, it was found that 316L suffered from crevice corrosion. On the other hand, 2205 stainless steel did not show any localized crevice corrosion, although the surface of 2205 was covered with corrosion products, formed when coupled to NiTi and stainless steel wires. This study indicates that considering corrosion resistance, 2205 duplex stainless steel is an improved alternative to 316L for orthodontic bracket fabrication when used in conjunction with titanium, its alloys, or stainless steel arch wires.

Corrosion resistance characterization of porous alumina membrane supports

Energy Technology Data Exchange (ETDEWEB)

Dong Yingchao, E-mail: dongyc9@mail.ustc.edu.cn [Materials and Surface Science Institute (MSSI), University of Limerick, Limerick (Ireland); USTC Lab for Solid State Chemistry and Inorganic Membranes, Department of Materials Science and Engineering, University of Science and Technology of China (USTC) (China); Key Lab of Jiangxi Universities for Inorganic Membranes, National Engineering Research Center for Domestic and Building Ceramics, Jingdezhen Ceramic University (JCU) (China); Lin Bin [USTC Lab for Solid State Chemistry and Inorganic Membranes, Department of Materials Science and Engineering, University of Science and Technology of China (USTC) (China); Zhou Jianer [Key Lab of Jiangxi Universities for Inorganic Membranes, National Engineering Research Center for Domestic and Building Ceramics, Jingdezhen Ceramic University (JCU) (China); Zhang Xiaozhen [USTC Lab for Solid State Chemistry and Inorganic Membranes, Department of Materials Science and Engineering, University of Science and Technology of China (USTC) (China); Key Lab of Jiangxi Universities for Inorganic Membranes, National Engineering Research Center for Domestic and Building Ceramics, Jingdezhen Ceramic University (JCU) (China); Ling Yihan; Liu Xingqin; Meng Guangyao [USTC Lab for Solid State Chemistry and Inorganic Membranes, Department of Materials Science and Engineering, University of Science and Technology of China (USTC) (China); Hampshire, Stuart [Materials and Surface Science Institute (MSSI), University of Limerick, Limerick (Ireland)

2011-04-15

Tubular porous alumina ceramic membrane supports were fabricated by an extrusion-drying-sintering process and then characterized in detail in terms of corrosion resistance in both H{sub 2}SO{sub 4} and NaOH aqueous solutions. Variations in the properties of the alumina supports such as mass loss percent, mechanical strength, open porosity and pore size distribution were studied before and after corrosion under different conditions. In addition, the microstructures were analyzed using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction before and after corrosion. The fabricated porous alumina supports offer possibilities for some potential applications as micro-filtration or ultra-filtration membrane supports, as well as in the pre-treatment of strongly acidic industrial waste-liquids. - Research highlights: {yields} Porous alumina membrane supports fabricated by extrusion-drying-sintering process. {yields} Corrosion resistance in 20 wt.% H{sub 2}SO{sub 4} and 1, 5, 10 wt.% NaOH aqueous solutions. {yields} Rapid mass loss and loss of flexural strength occurred in hot NaOH solution. {yields} Resistant to strong acid corrosion with low mass loss, low flexural strength loss. {yields} Porous alumina supports have potential for treatment of strong acid waste liquids.

Microstructure and Corrosion Behavior of Ni-Alloy/CrN Nanolayered Coatings

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Hao-Hsiang Huang

2011-01-01

Full Text Available The Ni-alloy/CrN nanolayered coatings, Ni-Al/CrN and Ni-P/CrN, were deposited on (100 silicon wafer and AISI 420 stainless steel substrates by dual-gun sputtering technique. The influences of the layer microstructure on corrosion behavior of the nanolayered thin films were investigated. The bilayer thickness was controlled approximately 10 nm with a total coating thickness of 1m. The single-layer Ni-alloy and CrN coatings deposited at 350∘C were also evaluated for comparison. Through phase identification, phases of Ni-P and Ni-Al compounds were observed in the single Ni-alloy layers. On the other hand, the nanolayered Ni-P/CrN and Ni-Al/CrN coatings showed an amorphous/nanocrystalline microstructure. The precipitation of Ni-Al and Ni-P intermetallic compounds was suppressed by the nanolayered configuration of Ni-alloy/CrN coatings. Through Tafel analysis, the corr and corr values ranged from –0.64 to –0.33 V and 1.42×10−5 to 1.14×10−6 A/cm2, respectively, were deduced for various coating assemblies. The corrosion mechanisms and related behaviors of the coatings were compared. The coatings with a nanolayered Ni-alloy/CrN configuration exhibited a superior corrosion resistance to single-layer alloy or nitride coatings.

Study of corrosion behavior of carbon steel under seawater film using the wire beam electrode method

International Nuclear Information System (INIS)

Liu, Zaijian; Wang, Wei; Wang, Jia; Peng, Xin; Wang, Yanhua; Zhang, Penghui; Wang, Haijie; Gao, Congjie

2014-01-01

Corrosion behavior of carbon steel under seawater film with various thickness was investigated by the wire beam electrode (WBE) method. It was found that the corrosion rate of carbon steel increased significantly under thin seawater film than it was immersed in seawater. The current variation under seawater film indicated that the thickness of diffusion layer of oxygen was about 500 μm, and the maximal current appeared around 40 μm, at which corrosion rate transited from cathodic control to anodic control. The results suggest that WBE method is helpful to study the corrosion process under thin electrolyte film

Inhibition of intergranular stress corrosion cracking of sensitized type 304 stainless steel. Annual report

International Nuclear Information System (INIS)

Brown, B.F.

1977-01-01

The effectiveness of various inhibitors in mitigating stress corrosion cracking of stainless steel in hot aqueous environment was evaluated. The inhibitors studied were of three types: poly-oxy-anions, organic competitive absorbers, and simple cations; the corrosive medium was 4M NaCl acidified with H 2 SO 4 to ph of about 2.3. The following conclusions were reached: pH does not affect cracking kinetics in a sensitive way; cracking time is highly dependent on chloride concentrations; poly-oxy-anions do not perform well; organics offer some possibilities as inhibitors; cationic additives can have effects varying from trivial to total suppression of cracking--behavior is both cation and concentration dependent. 2 figures, 5 tables

Influence of Short-time Oxidation on Corrosion Properties of Directionally Solidified Superalloys with Different Orientations

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MA Luo-ning

2016-07-01

Full Text Available In order to investigate the corrosion performance on intersecting and longitudinal surfaces of unoxidized and oxidized directionally solidified superalloys, Ni-base directionally solidified superalloy DZ125 and Co-base directionally solidified superalloy DZ40M were selected. Oxidation behavior on both alloys with different orientations was investigated at 1050℃ at different times, simulating the oxidation process of vanes or blades in service; subsequent electrochemical performance in 3.5%NaCl aqueous solution was studied on two orientations of unoxidized and oxidized alloys, simulating the corrosion process of superalloy during downtime. The results show that grain boundaries and sub-boundaries of directionally solidified superalloys are susceptible to corrosion and thus longitudinal surface with lower area fraction of grain boundaries has higher corrosion resistance. Compared to intersecting surface of alloys, the structure of grain boundaries of longitudinal surface is less conducive to diffusion and thus the oxidation rate on longitudinal surface is lower. Formation of oxide layers on alloys after short-time oxidation provides protective effect and enhances the corrosion resistance.

Annealing Effect on Corrosion Behavior of the Beta-Quenched HANA Alloy

International Nuclear Information System (INIS)

Kim, Hyun Gil; Kim, Il Hyun; Choi, Byung Kwan; Park, Sang Yoon; Park, Jeong Yong; Jeong, Yong Hwan

2009-01-01

The advanced fuel cladding materials named as HANA cladding have been developed at KAERI for application of high burn-up and that cladding showed an improved performance in both in-pile and out-of-pile conditions. However, the cladding performance could be changed by the annealing conditions during the tube manufacturing process. Especially, the corrosion resistance is considerably sensitive to their microstructure which is determined by a manufacturing process in the high Nb-containing zirconium alloys. They reported that the corrosion properties of the Nb-containing Zr alloys were considerably affected by the microstructure conditions such as the Nb concentration in the matrix and the second phase types. Therefore, the corrosion behavior of HANA cladding having the high Nb could be considerably affected by the annealing time and temperatures. The purpose of this study is focused on the annealing effect of the beta quenched HANA alloy to obtain the optimum annealing conditions

Influence of 8-hydroxyquinoline addition on the corrosion behavior of commercial Al and Al-HO411 alloys in NaOH aqueous media

International Nuclear Information System (INIS)

Soliman, H.N.

2011-01-01

Highlights: → The corrosion of commercial Al alloy is higher than that of Al-HO411 alloy. → The inhibition efficiency increases with the increasing of 8-hydroxyquinoline (8HQ) concentration. → The inhibition efficiencies of Al-HO411 samples are higher than those of commercial Al. → The 8HQ is promising candidate to be added to the coating systems as active anti-corrosive component for corrosion protection of both alloys. - Abstract: The effect of 8-hydroxyquinoline (8HQ) on the corrosion inhibition of commercial Al and Al-HO411 alloys has been investigated in NaOH solutions. Results showed that the inhibition efficiency was increased with increasing concentration of 8HQ. Al-HO411 alloy exhibited higher corrosion resistance and inhibition efficiency than the commercial Al. Examination of both samples was studied by means of optical microscope as well as energy-dispersive X-ray spectrometer. The crystallographic structure of both samples was analyzed by means of X-ray diffractometry. It was observed that protective films are formed on the surfaces that play an essential role in the corrosion inhibition of the alloys under investigation.

Comparison of the long-time corrosion behavior of certain Zr alloys in PWR, BWR, and laboratory tests

International Nuclear Information System (INIS)

Garzarolli, F.; Broy, Y.; Busch, R.A.

1996-01-01

Laboratory corrosion tests have always been an important tool for Zr alloy development and optimization. However, it must be known whether a test is representative for the application in-reactor. To shed more light on this question, coupons of several Zr alloys were exposed under isothermal conditions in BWR and PWR type environments. For evaluation of the in-PWR tests and for comparison of out-of-pile and in-pile tests, the different temperatures and times were normalized to a temperature-independent normalized time by assuming an activation temperature (Q/R) of 14,200 K. Comparison of in-PWR and out-of-pile corrosion behavior of Zircaloy shows that corrosion deviates to higher values in PWR if a weight gain of about 50 mg/dm 2 is exceeded. In the case of the Zr2.5Nb alloy, a slight deviation of corrosion as compared to laboratory results starts in PWR only above a weight gain of 100 mg/dm 2 . In BWR, corrosion of Zircaloy is enhanced early in time if compared with out-of-pile. Zr2.5Nb exhibits higher corrosion results in BWR than Zircaloy-4. Alloying chemistry and material condition affect corrosion of Zr alloys. However, several of the material parameters have shown a different ranking in the different environments. Nevertheless, several material parameters influencing in-reactor corrosion like the second phase particle (SPP) size of in-PWR behavior as the Sn and Fe content can be optimized by out-of-pile corrosion tests

Polarization and EIS studies to evaluate the effect of aluminum concentration on the corrosion behavior of SAC105 solder alloy

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Liyana N. K.

2018-03-01

Full Text Available This paper presents an investigation on corrosion behavior of Sn-1.0Ag-0.5Cu-XAl (X = 0, 0.1, 0.5, 1.0 by means of polarization and electrochemical impedance spectroscopy (EIS measurements in 3.5 wt.% NaCl solution. The results show that addition of aluminum into SAC105 shifts the corrosion current density and passivation current density towards more positive values. It is also found that with an increase in aluminum concentration in SAC105 solder alloy, the corrosion current density increases and polarization resistance decreases. This suggests that SAC105 with the highest concentration of Al has the lowest corrosion resistance. In this case, the corrosion behavior seems to be attributed to anodic dissolution of aluminum and Sn-matrix.

Properties, weldability and corrosion behavior of supermartensitic stainless steels for on- and offshore applications

Energy Technology Data Exchange (ETDEWEB)

Taban, Emel; Kaluc, Erdinc; Ojo, Olatunji Oladimeji [Kocaeli Univ. (Turkey). Welding Research, Education and Training Center

2016-08-01

Stimulated material-environment interactions inside and around flowlines of deep or ultra deep wells during oil and gas exploration, and fabrication economy of pipelines have been the major challenges facing the oil and gas industries. Presumably, an extensive focus on high integrity, performance and material economy of flowlines have realistically made supermartensitic stainless steels (SMSS) efficient and effective material choices for fabricating onshore and offshore pipelines. Supermartensitic stainless steels exhibit high strength, good low temperature toughness, sufficient corrosion resistance in sweet and mildly sour environments, and good quality weldability with both conventional welding processes and modern welding methods such as laser beam welding, electron beam welding and hybrid welding approaches. In terms of economy, supermartensitic stainless steels are cheaper and they are major replacements for more expensive duplex stainless steels required for tubing applications in the oil and gas industry. However, weld areas of SMSS pipes are exposed to sulphide stress cracking (SSC), so intergranular stress corrosion cracking (IGSCC) or stress corrosion cracking can occur. In order to circumvent this risk of cracking, a post-weld heat treatment (PWHT) for 5 minutes at about 650 C is recommended. This paper provides detailed literature perusal on supermartensitic stainless steels, their weldability and corrosion behaviors. It also highlights a major research area that has not been thoroughly expounded in literature; fatigue loading behaviors of welded SMSS under different corrosive environments have not been thoroughly detailed in literature.

Structural Characteristics and Corrosion Behavior of Bio-Degradable Zn-Li Alloys in Stent Application

Science.gov (United States)

Zhao, Shan

Zinc has begun to be studied as a bio-degradable material in recent years due to its excellent corrosion rate and optimal biocompatibility. Unfortunately, pure Zn's intrinsic ultimate tensile strength (UTS; below 120 MPa) is lower than the benchmark (about 300 MPa) for cardiovascular stent materials, raising concerns about sufficient strength to support the blood vessel. Thus, modifying pure Zn to improve its mechanical properties is an important research topic. In this dissertation project, a new Zn-Li alloy has been developed to retain the outstanding corrosion behavior from Zn while improving the mechanical characteristics and uniform biodegradation once it is implanted into the artery of Sprague-Dawley rats. The completed work includes: Manufactured Zn-Li alloy ingots and sheets via induction vacuum casting, melt spinning, hot rolling deformation, and wire electro discharge machining (wire EDM) technique; processed alloy samples using cross sectioning, mounting, etching and polishing technique; • Characterized alloy ingots, sheets and wires using hardness and tensile test, XRD, BEI imaging, SEM, ESEM, FTIR, ICP-OES and electrochemical test; then selected the optimum composition for in vitro and in vivo experiments; • Mimicked the degradation behavior of the Zn-Li alloy in vitro using simulated body fluid (SBF) and explored the relations between corrosion rate, corrosion products and surface morphology with changing compositions; • Explanted the Zn-Li alloy wire in abdominal aorta of rat over 12 months and studied its degradation mechanism, rate of bioabsorption, cytotoxicity and corrosion product migration from histological analysis.

Properties, weldability and corrosion behavior of supermartensitic stainless steels for on- and offshore applications

International Nuclear Information System (INIS)

Taban, Emel; Kaluc, Erdinc; Ojo, Olatunji Oladimeji

2016-01-01

Stimulated material-environment interactions inside and around flowlines of deep or ultra deep wells during oil and gas exploration, and fabrication economy of pipelines have been the major challenges facing the oil and gas industries. Presumably, an extensive focus on high integrity, performance and material economy of flowlines have realistically made supermartensitic stainless steels (SMSS) efficient and effective material choices for fabricating onshore and offshore pipelines. Supermartensitic stainless steels exhibit high strength, good low temperature toughness, sufficient corrosion resistance in sweet and mildly sour environments, and good quality weldability with both conventional welding processes and modern welding methods such as laser beam welding, electron beam welding and hybrid welding approaches. In terms of economy, supermartensitic stainless steels are cheaper and they are major replacements for more expensive duplex stainless steels required for tubing applications in the oil and gas industry. However, weld areas of SMSS pipes are exposed to sulphide stress cracking (SSC), so intergranular stress corrosion cracking (IGSCC) or stress corrosion cracking can occur. In order to circumvent this risk of cracking, a post-weld heat treatment (PWHT) for 5 minutes at about 650 C is recommended. This paper provides detailed literature perusal on supermartensitic stainless steels, their weldability and corrosion behaviors. It also highlights a major research area that has not been thoroughly expounded in literature; fatigue loading behaviors of welded SMSS under different corrosive environments have not been thoroughly detailed in literature.

Chemically activated nanodiamonds for aluminum alloy corrosion protection and monitoring

Science.gov (United States)

Hannstein, Inga; Adler, Anne-Katrin; Lapina, Victoria; Osipov, Vladimir; Opitz, Jörg; Schreiber, Jürgen; Meyendorf, Norbert

2009-03-01

In the present study, a smart coating for light metal alloys was developed and investigated. Chemically activated nanodiamonds (CANDiT) were electrophoretically deposited onto anodized aluminum alloy AA2024 substrates in order to increase corrosion resistance, enhance bonding properties and establish a means of corrosion monitoring based on the fluorescence behavior of the particles. In order to create stable aqueous CANDiT dispersions suitable for electrophoretic deposition, mechanical milling had to be implemented under specific chemical conditions. The influence of the CANDiT volume fraction and pH of the dispersion on the electrochemical properties of the coated samples was investigated. Linear voltammetry measurements reveal that the chemical characteristics of the CANDiT dispersion have a distinct influence on the quality of the coating. The fluorescence spectra as well as fluorescence excitation spectra of the samples show that corrosion can be easily detected by optical means. Furthermore, an optimization on the basis of "smart" - algorithms for the data processing of a surface analysis by the laser-speckle-method is presented.

Influence of Element Substitution on Corrosion Behavior of Bi2Te3-Based Compounds

Science.gov (United States)

Kohri, Hitoshi; Yagasaki, Takayoshi

2018-02-01

Atmospheric water may condense on the surface of Bi2Te3-based compounds constituting the Peltier module, depending on the operating environment used. In the stage of disposal, Bi2Te3-based compounds may come into contact with water in waste disposal sites. There are very few publications about the influence of condensed water on Peltier modules. Bi2Te3-Sb2Te3 or Bi2Te3-Bi2Se3 pseudo binary system compounds are used as p-type material or n-type material, respectively. The lattice distortion will be induced in the crystal of Bi2Te3-based compounds by element substitution due to the reduction in their thermal conductivity. However, the influence of element substitution on the corrosion behavior of Bi2Te3-based compounds remains unclear. In this study, the influence of element substitution on the corrosion behavior of Bi2Te3-based compounds with practical compositions has been investigated. Bi0.5Sb1.5Te3 or Bi2Te2.85Se0.15 was prepared by the vertical Bridgman method. The electrochemical properties at room temperature were evaluated by cyclic voltammetry in a standard three-electrode cell. The working electrolyte was a naturally aerated 0.6 or 3.0 mass% NaCl solution. From the tendency for corrosion potential for all the samples, the corrosion sensitivity of ternary compounds was slightly higher than that of binary compounds. From the trend of current density, it was found that Bi0.5Sb1.5Te3 had a corrosion resistance intermediate between Bi2Te3 and Sb2Te3. On the other hand, corrosion resistance was affected despite a small amount of Se substitution, and the corrosion resistance of Bi2Te2.85Se0.15 was close to or lower than that of Bi2Se3. From the observation results of the corrosion products, the trends of morphology and composition of corrosion products for Bi0.5Sb1.5Te3 or Bi2Te2.85Se0.15 were consistent with those of Sb2Te3 or Bi2Se3, respectively. From the results of x-ray photoelectron spectroscopy for the electrolyte after testing, the possibility that a

Influence of Element Substitution on Corrosion Behavior of Bi2Te3-Based Compounds

Science.gov (United States)

Kohri, Hitoshi; Yagasaki, Takayoshi

2018-06-01

Atmospheric water may condense on the surface of Bi2Te3-based compounds constituting the Peltier module, depending on the operating environment used. In the stage of disposal, Bi2Te3-based compounds may come into contact with water in waste disposal sites. There are very few publications about the influence of condensed water on Peltier modules. Bi2Te3-Sb2Te3 or Bi2Te3-Bi2Se3 pseudo binary system compounds are used as p-type material or n-type material, respectively. The lattice distortion will be induced in the crystal of Bi2Te3-based compounds by element substitution due to the reduction in their thermal conductivity. However, the influence of element substitution on the corrosion behavior of Bi2Te3-based compounds remains unclear. In this study, the influence of element substitution on the corrosion behavior of Bi2Te3-based compounds with practical compositions has been investigated. Bi0.5Sb1.5Te3 or Bi2Te2.85Se0.15 was prepared by the vertical Bridgman method. The electrochemical properties at room temperature were evaluated by cyclic voltammetry in a standard three-electrode cell. The working electrolyte was a naturally aerated 0.6 or 3.0 mass% NaCl solution. From the tendency for corrosion potential for all the samples, the corrosion sensitivity of ternary compounds was slightly higher than that of binary compounds. From the trend of current density, it was found that Bi0.5Sb1.5Te3 had a corrosion resistance intermediate between Bi2Te3 and Sb2Te3. On the other hand, corrosion resistance was affected despite a small amount of Se substitution, and the corrosion resistance of Bi2Te2.85Se0.15 was close to or lower than that of Bi2Se3. From the observation results of the corrosion products, the trends of morphology and composition of corrosion products for Bi0.5Sb1.5Te3 or Bi2Te2.85Se0.15 were consistent with those of Sb2Te3 or Bi2Se3, respectively. From the results of x-ray photoelectron spectroscopy for the electrolyte after testing, the possibility that a

Effect of Sn addition on the corrosion behavior of Ti-7Cu-Sn cast alloys for biomedical applications.

Science.gov (United States)

Tsao, L C

2015-01-01

The aim of this study was to investigate the effects of Sn content on the microstructure and corrosion resistance of Ti7CuXSn (x=0-5 wt.%) samples. The corrosion tests were carried out in 0.9 wt.% NaCl solution at 25 °C. The electrochemical corrosion behavior of the Ti7CuXSn alloy samples was evaluated using potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), and equivalent circuit analysis. The resulting impedance parameters and polarization curves showed that adding Sn improved the electrochemical corrosion behavior of the Ti7CuXSn alloy. The Ti7CuXSn alloy samples were composed of a dual-layer oxide consisting of an inner barrier layer and an outer porous layer. Copyright © 2014 Elsevier B.V. All rights reserved.

The effect of various deformation processes on the corrosion behavior of casing and tubing carbon steels in sweet environment

Science.gov (United States)

Elramady, Alyaa Gamal

The aim of this research project is to correlate the plastic deformation and mechanical instability of casing steel materials with corrosion behavior and surface change, in order to identify a tolerable degree of deformation for casing steel materials. While the corrosion of pipeline and casing steels has been investigated extensively, corrosion of these steels in sweet environments with respect to plastic deformation due to bending, rolling, autofrettage, or handling needs more investigation. Downhole tubular expansion of pipes (casings) is becoming standard practice in the petroleum industry to repair damaged casings, shutdown perforations, and ultimately achieve mono-diameter wells. Tubular expansion is a cold-drawing metal forming process, which consists of running conical mandrels through casings either mechanically using a piston or hydraulically by applying a back pressure. This mechanism subjects the pipes to large radial plastic deformations of up to 30 pct. of the inner diameter. It is known that cold-working is a way of strengthening materials such as low carbon steel, but given that this material will be subjected to corrosive environments, susceptibility to stress corrosion cracking (SCC) should be investigated. This research studies the effect of cold-work, in the form of cold-rolling and cold-expansion, on the surface behavior of API 5CT steels when it is exposed to a CO2-containing environment. Cold-work has a pronounced influence on the corrosion behavior of both API 5CT K55 and P110 grade steels. The lowest strength grade steel, API 5CT K55, performed poorly in a corrosive environment in the slow strain rate test. The ductile material exhibited the highest loss in strength and highest susceptibility to stress corrosion cracking in a CO 2-containing environment. The loss in strength declined with cold-rolling, which can be ascribed to the surface compressive stresses induced by cold-work. On the other hand, API 5CT P110 grade steels showed higher

Quantitative analysis of hydrogen gas formed by aqueous corrosion of metallic uranium

International Nuclear Information System (INIS)

Fonnesbeck, J.

2000-01-01

Three unirradiated EBR-II blanket fuel samples containing depleted uranium metal were corrosion tested in simulated J-13 well water at 90 C. The corrosion rate of the blanket uranium metal was then determined relative to H 2 formation. Corrosion of one of the samples was interrupted prior to complete oxidation of the uranium metal and the solid corrosion product was analyzed for UO 2 and UH 3

Quantitative analysis of hydrogen gas formed by aqueous corrosion of metallic uranium

Energy Technology Data Exchange (ETDEWEB)

Fonnesbeck, J.

2000-03-20

Three unirradiated EBR-II blanket fuel samples containing depleted uranium metal were corrosion tested in simulated J-13 well water at 90 C. The corrosion rate of the blanket uranium metal was then determined relative to H{sub 2} formation. Corrosion of one of the samples was interrupted prior to complete oxidation of the uranium metal and the solid corrosion product was analyzed for UO{sub 2} and UH{sub 3}.

Strength and corrosion behavior of SiC - based ceramics in hot coal combustion environments

Energy Technology Data Exchange (ETDEWEB)

Breder, K.; Parten, R.J. [Oak Ridge National Lab., TN (United States)

1996-08-01

As part of an effort to evaluate the use of advanced ceramics in a new generation of coal-fired power plants, four SiC-based ceramics have been exposed to corrosive coal slag in a laboratory furnace and two pilot scale combustors. Initial results indicate that the laboratory experiments are valuable additions to more expensive pilot plant experiments. The results show increased corrosive attack with increased temperature, and that only slight changes in temperature may significantly alter the degree of strength degradation due to corrosive attack. The present results are part of a larger experimental matrix evaluating the behavior of ceramics in the coal combustion environment.

Effect of Nb on the Microstructure, Mechanical Properties, Corrosion Behavior, and Cytotoxicity of Ti-Nb Alloys.

Science.gov (United States)

Han, Mi-Kyung; Kim, Jai-Youl; Hwang, Moon-Jin; Song, Ho-Jun; Park, Yeong-Joon

2015-09-09

In this paper, the effects of Nb addition (5-20 wt %) on the microstructure, mechanical properties, corrosion behavior, and cytotoxicity of Ti-Nb alloys were investigated with the aim of understanding the relationship between phase/microstructure and various properties of Ti-xNb alloys. Phase/microstructure was analyzed using X-ray diffraction (XRD), SEM, and TEM. The results indicated that the Ti-xNb alloys (x = 10, 15, and 20 wt %) were mainly composed of α + β phases with precipitation of the isothermal ω phase. The volume percentage of the ω phase increased with increasing Nb content. We also investigated the effects of the alloying element Nb on the mechanical properties (including Vickers hardness and elastic modulus), oxidation protection ability, and corrosion behavior of Ti-xNb binary alloys. The mechanical properties and corrosion behavior of Ti-xNb alloys were found to be sensitive to Nb content. These experimental results indicated that the addition of Nb contributed to the hardening of cp-Ti and to the improvement of its oxidation resistance. Electrochemical experiments showed that the Ti-xNb alloys exhibited superior corrosion resistance to that of cp-Ti. The cytotoxicities of the Ti-xNb alloys were similar to that of pure titanium.

Corrosion behavior of amorphous and crystalline Cu50Ti50 and Cu50Zr50 alloys

International Nuclear Information System (INIS)

Naka, M.; Hoshimoto, K.; Masumoto, T.

1978-01-01

Corrosion rates and anodic polarization curves of amorphous and crystalline Cu 50 Ti 50 and Cu 50 Zr 50 alloys have been examined in various acidic, neutral and alkaline solutions. The amorphous alloys are very stable in acidic and alkaline solutions, but unstable in agressive chloride solutions. The corrosion resistance of these amorphous alloys is higher than that of the crystallized alloys. The high corrosion resistance of amorphous alloys is attributable to the high chemical homogeneity of amorphous alloys without localized crystalline defects such as precipitates, segregates, grain boundaries, etc. Metalloid elements play an important role in the corrosion behavior of amorphous alloys; the addition of phosphorus to amorphous Cu-Ti alloy greatly increases the corrosion resistance, even in 1N HCl. (Auth.)

A Revisit to the Corrosion Inhibition of Aluminum in Aqueous Alkaline Solutions by Water-Soluble Alginates and Pectates as Anionic Polyelectrolyte Inhibitors

Directory of Open Access Journals (Sweden)

Refat Hassan

2013-01-01

Full Text Available The corrosion behavior of aluminum (Al in alkaline media in presence of some natural polymer inhibitors has been reinvestigated. The inhibition action of the tested inhibitors was found to obey both Langmuir and Freundlich isotherms models. The inhibition efficiency was found to increase with increasing the inhibitors concentration and decrease with increasing the temperature, suggesting physical adsorption mechanism. Factors such as the concentration and geometrical structure of the inhibitor, concentration of the corrosive medium, and temperature affecting the corrosion rates were examined. The kinetic parameters were evaluated, and a suitable corrosion mechanism consistent with the kinetic results obtained is suggested and discussed.

Corrosion behavior of a self-sealing pore micro-arc oxidation film on AM60 magnesium alloy

International Nuclear Information System (INIS)

Dong, Kaihui; Song, Yingwei; Shan, Dayong; Han, En-Hou

2015-01-01

Highlights: • Pore sealing constituents fall off and titanium oxides remain during corrosion. • Dark regions of film are corroded by migration of corrosion media through pores. • Light regions of film are corroded by transverse expansion of cracks. • Both outer and inner layers of the film provide effective protection to substrate. - Abstract: The deterioration process of a self-sealing pore micro-arc oxidation (MAO) film was investigated. The surface and cross-section corrosion morphologies were observed by scanning electron microscopy (SEM). Chemical composition was detected by EDS elemental mapping and XRD. The corrosion process was analyzed by electrochemical impedance spectroscopy (EIS). The surface of the film in dark and light regions exhibits different corrosion behavior. In the dark regions, the corrosion process mainly concentrates on the migration of corrosion media through the pores inward. In the light regions, the transverse expansion of cracks plays a key role, accompanying the exfoliation of film constituents.

Corrosion behavior of Si-enriched steels for nuclear applications in liquid lead–bismuth

Energy Technology Data Exchange (ETDEWEB)

Kurata, Yuji, E-mail: kurata.yuji@jaea.go.jp [Japan Atomic Energy Agency, Tokai-mura, Ibaraki-ken 319-1195 (Japan)

2013-06-15

Highlights: ► The corrosion behavior of Si-enriched steels in liquid lead–bismuth was studied. ► The corrosion tests were conducted at the two controlled oxygen levels. ► The Si addition reduces the scale thickness under the high oxygen condition. ► The Si addition has no significant effect under the low oxygen condition. -- Abstract: The corrosion behavior of Si-enriched steels in liquid lead–bismuth was studied in order to develop accelerator driven systems for transmutation of long-lived radioactive wastes and lead–bismuth cooled fast reactors. The corrosion tests of 316SS, Si-enriched 316SS, Mod.9Cr–1Mo steel (T91) and Si-enriched T91 were conducted at 550 °C in liquid lead–bismuth at the two controlled oxygen levels. Both the additions of 2.5 wt.% Si to 316SS and 1.5 wt.% Si to T91 had the effect of reducing the thickness of oxide layer in liquid lead–bismuth at the high oxygen concentration (2.5 × 10{sup −5} wt.%). Although the Si addition to 316SS reduced the depth of ferritization caused by Ni dissolution in liquid lead–bismuth at the low oxygen concentration (4.4 × 10{sup −8} wt.%), it could not suppress the ferritization and the penetration of Pb and Bi completely. The Si addition to T91 did not have the effect of preventing the penetration of Pb and Bi in the liquid lead–bismuth at the low oxygen concentration. The oxide scales formed on both Si-enriched steels did not have sufficient corrosion resistance under the low oxygen condition.

Effect of H2O2 on the corrosion behavior of 304L stainless steel

International Nuclear Information System (INIS)

Song, Taek Ho

1994-02-01

In connection with the safe storage of high level nuclear waste, effect of H 2 O 2 on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H 2 O 2 . The experimental results show that H 2 O 2 increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H 2 O 2 concentration increased, indicating that pitting resistance was decreased by the existence of H 2 O 2 in the electrolyte. These effects of H 2 O 2 on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H 2 O 2 with those of O 2 , cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H 2 O 2 on the corrosion behavior were very similar to those of O 2 such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. Further, H 2 O 2 played much greater role in controlling cathodic reaction rate in neutral water environment. In acid and alkaline media, potential shifts by H 2 O 2 were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively

Corrosion behavior in high heat input welded heat-affected zone of Ni-free high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel

International Nuclear Information System (INIS)

Moon, Joonoh; Ha, Heon-Young; Lee, Tae-Ho

2013-01-01

The pitting corrosion and interphase corrosion behaviors in high heat input welded heat-affected zone (HAZ) of a metastable high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel were explored through electrochemical tests. The HAZs were simulated using Gleeble simulator with high heat input welding condition of 300 kJ/cm and the peak temperature of the HAZs was changed from 1200 °C to 1350 °C, aiming to examine the effect of δ-ferrite formation on corrosion behavior. The electrochemical test results show that both pitting corrosion resistance and interphase corrosion resistance were seriously deteriorated by δ-ferrite formation in the HAZ and their aspects were different with increasing δ-ferrite fraction. The pitting corrosion resistance was decreased by the formation of Cr-depleted zone along δ-ferrite/austenite (γ) interphase resulting from δ-ferrite formation; however it didn't depend on δ-ferrite fraction. The interphase corrosion resistance depends on the total amount of Cr-depleted zone as well as ferrite area and thus continuously decreased with increasing δ-ferrite fraction. The different effects of δ-ferrite fraction on pitting corrosion and interphase corrosion were carefully discussed in terms of alloying elements partitioning in the HAZ based on thermodynamic consideration. - Highlights: • Corrosion behavior in the weld HAZ of high-nitrogen austenitic alloy was studied. • Cr 2 N particle was not precipitated in high heat input welded HAZ of tested alloy. • Pitting corrosion and interphase corrosion show a different behavior. • Pitting corrosion resistance was affected by whether or not δ-ferrite forms. • Interphase corrosion resistance was affected by the total amount of δ-ferrite

Aqueous corrosion of silicate glasses. Analogy between volcanic glasses and the French nuclear waste glass R7T7

International Nuclear Information System (INIS)

Goldschmidt, F.

1991-01-01

The behaviour of borosilicate glasses upon aqueous corrosion is controlled for long periods of time (>10,000 years) by processes which are not directly accessible by means of laboratory experiments. The analogical approach consists here to compare leaching performances between the french nuclear waste glass R7T7 and natural volcanic glasses, basaltic and rhyolitic ones. The three glasses were leached in the same conditions; open system, 90 deg C, initial pH of 9.7. Basaltic and R7T7 glasses having the same kinetic of dissolution, the basaltic glass was chosen as the best analogue. (author). refs., figs., tabs

Influence of turbulent flow on the corrosion kinetics of API X52 pipeline steel in aqueous solutions containing H{sub 2}S

Energy Technology Data Exchange (ETDEWEB)

Galvan-Martinez, Ricardo; Genesca-Llongueras, Juan [Departamento Ingenieria Metalurgica, Facultad Quimica, Universidad Nacional Autonoma de Mexico, UNAM, Ciudad Universitaria, 04510 Mexico D.F. (Mexico); Mendoza-Flores, Juan; Duran-Romero, Ruben [Corrosion, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, 07730 Mexico D.F. (Mexico)

2004-07-01

A corrosion process can be influenced by the relative movement between the corroding environment and the metal. This relative movement could increase the heat transfer and the mass transfer of reactants towards and from the surface of the corroding metal, with a consequent increase in the corrosion rate. Also, if solid particles are present, removal of protective films, erosion and wear can occur on the metallic surface. Many industrial processes involve the movement of corrosive liquids in close contact to metallic structures. Therefore, the influence of flow on the corrosion processes is an important issue to be considered in the design and operation of industrial equipment. This influence is complex and many variables are involved. Several observations of flow-accelerated corrosion problems have been documented, particularly in the oil and gas industries, where the combined effect of flow and dissolved gases, such as hydrogen sulphide (H{sub 2}S) and carbon dioxide (CO{sub 2}), is important. Turbulent flow conditions are commonly found in industrial processes. However, few corrosion studies in controlled turbulent flow conditions are available. With the increasing necessity to describe the corrosion of metals in turbulent flow conditions some laboratory hydrodynamic systems have been used with different degrees of success. The use of the rotating cylinder electrode (RCE), as a laboratory hydrodynamic test system, has gained popularity in corrosion studies. This popularity is due to its characteristics, such as, its operation mainly at turbulent flow conditions; its well understood mass transfer properties and its easiness of construction and operation. The aim of the present work is to explore the effect that turbulent flow conditions have on the electrochemical kinetics of steel samples immersed in aqueous environments containing H{sub 2}S. In order to control the turbulent flow conditions in the laboratory, a rotating cylinder electrode (RCE) was used. In

Study of the corrosion behavior and the corrosion films formed on the surfaces of Mg–xSn alloys in 3.5 wt.% NaCl solution

International Nuclear Information System (INIS)

Wang, Jingfeng; Li, Yang; Huang, Song; Zhou, Xiaoen

2014-01-01

Highlights: • Corrosion of four cast Mg–xSn alloys in 3.5 wt.% NaCl solution was investigated. • Both Mg(OH) 2 /SnO 2 corrosion product film and Mg(OH) 2 /MgSnO 3 clusters formed on Mg–1.5Sn. • Compact Mg(OH) 2 /MgSnO 3 film suppressed the cathodic effect of the impurity inclusions. • Mg–xSn (x = 0.5, 1.0, 2.0 wt.%) alloys only formed loose Mg(OH) 2 /SnO 2 corrosion product film. - Abstract: The corrosion behavior and the corrosion films formed on the surfaces of Mg–xSn (x = 0.5, 1.0, 1.5, and 2.0 wt.%) alloys in 3.5 wt.% NaCl solution were investigated by immersion tests, electrochemical measurements, corrosion morphology observations, and X-ray diffraction analysis. Immersion tests and electrochemical measurements illustrated that the best corrosion resistance was reported for the Mg–1.5Sn alloy. Both Mg(OH) 2 /SnO 2 corrosion product film and Mg(OH) 2 /MgSnO 3 clusters formed on Mg–1.5Sn alloy surface. Mg(OH) 2 /MgSnO 3 clusters were compact and suppressed the cathodic effect of the impurity inclusions greatly. The Mg–xSn (x = 0.5, 1.0, and 2.0 wt.%) alloys only formed loose Mg(OH) 2 /SnO 2 corrosion product film during the corrosion process

Slow positron beam study of corrosion behavior of AM60B magnesium alloy in NaCl solution