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Sample records for aqueous corrosion behavior

  1. Corrosion behavior of bulk metallic glasses in different aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The corrosion behavior of as-cast fully amorphous, structural relaxed amorphous and crystallized Fe65.5Cr4Mo4Ga4P12C5B5.5 bulk metallic glasses (BMGs) in NaCl, HCl and NaOH solutions was investigated by electrochemical polarization and immersion methods. X-ray photoelectron spectroscopy measurements was used to analyze the changes of the elements on the alloy surface before and after immersion in various solutions. The corrosion resistance of the Fe65.5Cr4Mo4Ga4P12C5B5.5 BMG was better than its structural relaxation/crystallization counterparts and common alloys (such as stainless steel, carbonized steel, and steel) in the selected aqueous solutions. The high corrosion resistance of this alloy in corrosive solutions leads to the formation of Fe-, Cr- and Mo-enriched protective thin surface films.

  2. 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)

  3. Effect of silty sand with different sizes on corrosion behavior of 3Cr steel in CO2 aqueous environment

    Science.gov (United States)

    Liu, Wei; Lu, Songle; Zhang, Peng; Dou, Juanjuan; Zhao, Qinghe

    2016-08-01

    Corrosion behavior of 3Cr steel in CO2 aqueous environment containing silty sand was investigated by immersion test. The results show that CO2 corrosion rate and morphology of 3Cr steel were obviously affected by the size of silty sand. 5000 mesh silty sand mixed with corrosion products, forming compact Cr-rich corrosion scale and resulting in low corrosion rate and uniform corrosion. 1000 mesh silty sand mixed with corrosion products, forming porous corrosion scale without Cr enrichment and resulting in high corrosion rate and pitting corrosion. 5000 mesh silty sand enhanced Cr enrichment in corrosion scale, leading to low anodic current. However, 1000 mesh silty sand deteriorated Cr enrichment in corrosion scale, leading to high anodic current. Cathodic current was reduced by silty sand, but was not affected by two sizes of silty sand. Cr enrichment in corrosion scale of 3Cr steel was obviously affected by separation effect of silty sand.

  4. Corrosion behavior of technetium waste forms exposed to various aqueous environments

    Energy Technology Data Exchange (ETDEWEB)

    Kolman, David Gary [Los Alamos National Laboratory; Jarvinen, Gordon [Los Alamos National Laboratory; Mausolf, Edward [UNIV OF NEVADA; Czerwinski, Ken [UNIV OF NEVADA; Poineau, Frederic [UNIV OF NEVADA

    2009-01-01

    Technetium is a long-lived beta emitter produced in high yields from uranium as a waste product in spent nuclear fuel and has a high degree of environmental mobility as pertechnetate. It has been proposed that Tc be immobilized into various metallic waste forms to prevent Tc mobility while producing a material that can withstand corrosion exposed to various aqueous medias to prevent the leachability of Tc to the environment over long periods of time. This study investigates the corrosion behavior of Tc and Tc alloyed with 316 stainless steel and Zr exposed to a variety of aqueous media. To date, there is little investigative work related to Tc corrosion behavior and less related to potential Tc containing waste forms. Results indicate that immobilizing Tc into stainless steel-zirconium alloys can be a promising technique to store Tc for long periods of time while reducing the need to separately store used nuclear fuel cladding. Initial results indicate that metallic Tc and its alloys actively corrode in all media. We present preliminary corrosion rates of 100% Tc, 10% Tc - 90% SS{sub 85%}Zr{sub 15%}, and 2% Tc - 98% SS{sub 85%}Zr{sub 15%} in varying concentrations of nitric acid and pH 10 NaOH using the resistance polarization method while observing the trend that higher concentrations of Tc alloyed to the sample tested lowers the corrosion rate of the proposed waste package.

  5. Aqueous Corrosion Behavior of Micro Arc Oxidation (MAO)-Coated Magnesium Alloys: A Critical Review

    Science.gov (United States)

    Rama Krishna, L.; Sundararajan, G.

    2014-06-01

    Magnesium (Mg) and its alloys, in the current era of persistently growing engineering demands, have become the most promising materials finding widespread industrial applications. Numerous processes are available for surface protection of Mg and its alloys to potentially minimize corrosion damage. The micro arc oxidation (MAO), a fairly recent and eco-friendly coating process, emerged as a novel means to provide an adherent, hard, scratch-resistant, wear-resistant, and corrosion-resistant coatings on Mg alloys. However, the successful utilization of such coatings demands a thorough understanding of the influence of a relatively large number of process parameters such as electrolytic composition, presence of insoluble additives in the electrolyte, electrical parameters employed, and the composition of the Mg alloy substrate on the corrosion resistance. The detailed influence of all the above parameters on the corrosion behavior of Mg alloys is critically reviewed and presented in this article. In addition, this article also reviews the recent trends in terms of duplexing the MAO process using different techniques/processes such that the composite coatings are produced with enhanced corrosion resistance.

  6. Corrosion problems with aqueous coolants, final report

    Energy Technology Data Exchange (ETDEWEB)

    Diegle, R B; Beavers, J A; Clifford, J E

    1980-04-11

    The results of a one year program to characterize corrosion of solar collector alloys in aqueous heat-transfer media are summarized. The program involved a literature review and a laboratory investigation of corrosion in uninhibited solutions. It consisted of three separate tasks, as follows: review of the state-of-the-art of solar collector corrosion processes; study of corrosion in multimetallic systems; and determination of interaction between different waters and chemical antifreeze additives. Task 1 involved a comprehensive review of published literature concerning corrosion under solar collector operating conditions. The reivew also incorporated data from related technologies, specifically, from research performed on automotive cooling systems, cooling towers, and heat exchangers. Task 2 consisted of determining the corrosion behavior of candidate alloys of construction for solar collectors in different types of aqueous coolants containing various concentrations of corrosive ionic species. Task 3 involved measuring the degradation rates of glycol-based heat-transfer media, and also evaluating the effects of degradation on the corrosion behavior of metallic collector materials.

  7. Effect of surface condition on the aqueous corrosion behavior of iron aluminies

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-08-01

    The effects of retained high-temperature surface oxides, produced during thermomechanical processing and/or heat treatment, on the aqueous-corrosion characteristics of Fe-Al-based alloys were evaluated by electrochemical methods. Cyclic anodic polarization evaluations were conducted at room temperature in a mild acid-chloride solution (pH = 4,200 ppm Cl{sup {minus}}) on the Fe{sub 3}Al-based iron aluminides, FA-84 (Fe-28Al-2Cr-0.05B, at %), FA-129 (Fe-28Al-5Cr-0.5Nb-0.2C, at %), and FAL-Mo (Fe-28Al-5Cr-1Mo-0.04B-0.08Zr, at %), on the FeAl-based iron aluminide, FA-385 (Fe-35.65Al-0.20Mo-0.05Zr-0.11C, at %). The surface conditions evaluated were: As received (i.e. with the retained high-temperature oxides), mechanically cleaned (ground through 600-grit SiC paper), and chemically cleaned (10% HNO{sub 3}, 2%HF, at 43 {degree}C). The principal electrochemical parameter of interest was the critical putting potential with lower values indicating less resistance to chloride-induced localized corrosion. For all materials evaluated, the critical pitting potential was found to be significantly lower in the as-received condition than in the mechanically-cleaned and chemically-cleaned conditions. Mechanisms responsible for the detrimental high-temperature-oxide effect are under study.

  8. Aqueous Corrosion Rates for Waste Package Materials

    Energy Technology Data Exchange (ETDEWEB)

    S. Arthur

    2004-10-08

    The purpose of this analysis, as directed by ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]), is to compile applicable corrosion data from the literature (journal articles, engineering documents, materials handbooks, or standards, and national laboratory reports), evaluate the quality of these data, and use these to perform statistical analyses and distributions for aqueous corrosion rates of waste package materials. The purpose of this report is not to describe the performance of engineered barriers for the TSPA-LA. Instead, the analysis provides simple statistics on aqueous corrosion rates of steels and alloys. These rates are limited by various aqueous parameters such as temperature (up to 100 C), water type (i.e., fresh versus saline), and pH. Corrosion data of materials at pH extremes (below 4 and above 9) are not included in this analysis, as materials commonly display different corrosion behaviors under these conditions. The exception is highly corrosion-resistant materials (Inconel Alloys) for which rate data from corrosion tests at a pH of approximately 3 were included. The waste package materials investigated are those from the long and short 5-DHLW waste packages, 2-MCO/2-DHLW waste package, and the 21-PWR commercial waste package. This analysis also contains rate data for some of the materials present inside the fuel canisters for the following fuel types: U-Mo (Fermi U-10%Mo), MOX (FFTF), Thorium Carbide and Th/U Carbide (Fort Saint Vrain [FSVR]), Th/U Oxide (Shippingport LWBR), U-metal (N Reactor), Intact U-Oxide (Shippingport PWR, Commercial), aluminum-based, and U-Zr-H (TRIGA). Analysis of corrosion rates for Alloy 22, spent nuclear fuel, defense high level waste (DHLW) glass, and Titanium Grade 7 can be found in other analysis or model reports.

  9. Aqueous Corrosion Rates for Waste Package Materials

    International Nuclear Information System (INIS)

    The purpose of this analysis, as directed by ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]), is to compile applicable corrosion data from the literature (journal articles, engineering documents, materials handbooks, or standards, and national laboratory reports), evaluate the quality of these data, and use these to perform statistical analyses and distributions for aqueous corrosion rates of waste package materials. The purpose of this report is not to describe the performance of engineered barriers for the TSPA-LA. Instead, the analysis provides simple statistics on aqueous corrosion rates of steels and alloys. These rates are limited by various aqueous parameters such as temperature (up to 100 C), water type (i.e., fresh versus saline), and pH. Corrosion data of materials at pH extremes (below 4 and above 9) are not included in this analysis, as materials commonly display different corrosion behaviors under these conditions. The exception is highly corrosion-resistant materials (Inconel Alloys) for which rate data from corrosion tests at a pH of approximately 3 were included. The waste package materials investigated are those from the long and short 5-DHLW waste packages, 2-MCO/2-DHLW waste package, and the 21-PWR commercial waste package. This analysis also contains rate data for some of the materials present inside the fuel canisters for the following fuel types: U-Mo (Fermi U-10%Mo), MOX (FFTF), Thorium Carbide and Th/U Carbide (Fort Saint Vrain [FSVR]), Th/U Oxide (Shippingport LWBR), U-metal (N Reactor), Intact U-Oxide (Shippingport PWR, Commercial), aluminum-based, and U-Zr-H (TRIGA). Analysis of corrosion rates for Alloy 22, spent nuclear fuel, defense high level waste (DHLW) glass, and Titanium Grade 7 can be found in other analysis or model reports

  10. Aqueous Corrosion Characteristics of Nickel Aluminides

    International Nuclear Information System (INIS)

    The aqueous corrosion characteristics of three nickel aluminides were studied by using (a) immersion corrosion test and (b) cyclic anodic polarization measurements. The immersion tests were conducted in 15 different solutions at 25 .deg. C and 95 .deg. C. The nickel aluminides were found to have good corrosion resistance in inorganic acids, organic acids and basic solutions 25 .deg. C except at a higher concentration of hydrochloric acid in ferric chloride solution at the temperature. All three nickel aluminides were suitably resistant to corrosion in the organic acids (oxalic acid, acetic acid), sodium chloride solution, and bases (sodium hydoxide, ammonium hydroxide) at 95 .deg. C. The cyclic anodic polarization curves were developed in N2-deaerated solution at 25 .deg. C and 95 .deg. C. In addition, open-circuit corrosion potentials were determined for the solutions in the aerated condition at 25 .deg. C to compare with the anodic curves. At 25 .deg. C, although all materials exhibited active-passive behavior in all solutions except the hydrofluoric acid, at Ecorr(aerated), passive corrosion was only indicated for the acetic acid, sodium hydroxide, and sodium chloride solutions. Nevertheless, in all cases, the predicted dissolution rates were consistent with immersion test results. Hysteresis loops indicating susceptibility to localized corrosion were observed in 0.6M sodium chloride(pH=7) solution. At 95 .deg. C, active-passive behavior was demonstrated in the acetic acid, sodium chloride, and to a limited extent in the nitric acid: but only active behavior was shown in the sulfuric and hydrofluoric acids. From the above results, it was noted that anodic dissolution of nickel aluminides significantly increased with increasing temperature and that the Cr-containing compositions had better corrosion resistance in several solutions than the Cr-free composition. Prior manufacturing procedures, i.e., casting and powder metallurgy processes did not appear to

  11. 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.

  12. Corrosion inhibition behavior of propyl phosphonic acid–Zn2+ system for carbon steel in aqueous solution

    International Nuclear Information System (INIS)

    The effectiveness of propyl phosphonic acid (PPA) as a corrosion inhibitor in association with a bivalent cation like Zn2+ has been studied. An eco-friendly inhibitor in controlling corrosion of carbon steel in neutral aqueous medium in the absence and presence of Zn2+ has been evaluated by gravimetric method. Impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the aqueous environment. Potentiodynamic polarization studies showed that the inhibitor is a mixed inhibitor. X-ray photoelectron spectroscopic analysis (XPS) of the protective film exhibited the presence of the elements viz., iron, phosphorus, oxygen, carbon and zinc. The chemical shifts in the binding energies of these elements inferred that the surface film is composed of oxides/hydroxides of iron(III), Zn(OH)2 and [Fe(II)/(III)–Zn(II)–PPA] complex. Further, the surface analysis techniques viz., FT-IR, AFM and SEM studies confirm the formation of an adsorbed protective film on the carbon steel surface. Based on all these results, a plausible mechanism of corrosion inhibition is proposed.

  13. The effect of pure iron in a nanocrystalline grain size on the corrosion inhibitor behavior of sodium benzoate in near-neutral aqueous solution

    International Nuclear Information System (INIS)

    The effect of grain size reduction on the electrochemical and corrosion behavior of iron with different grain sizes (32-750 nm) produced by direct and pulsed current electrodeposition were characterized using Tafel polarization curves and electrochemical impedance spectroscopy. The grain size of deposits was determined by X-ray diffraction analysis and scanning electron microscopy. The tests were carried out in an aqueous electrolyte containing 30 mg L-1 NaCl + 70 mg L-1 Na2SO4. Results obtained suggested that the inhibition effect and corrosion protection of sodium benzoate inhibitor in near-neutral aqueous solutions increased as the grain size decreased from microcrystalline to nanocrystalline. The improvement on the inhibition effect is attributed to the increase of the surface energy.

  14. Aqueous corrosion study on U-Zr alloy

    International Nuclear Information System (INIS)

    In low power or research reactor, U-Zr alloy is a potential candidate for dispersion fuel. Moreover, Zirconium has a low thermal-neutron cross section and uranium alloyed with Zr has excellent corrosion resistance and dimensional stability during thermal cycling. In the present study aqueous corrosion behavior of U-Zr alloy samples was studied in autoclave at 200 deg C temperature. Corrosion rate was determined from weight loss with time. (author)

  15. 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. PMID:21128496

  16. Humid-air and aqueous corrosion models for corrosion-allowance barrier material

    International Nuclear Information System (INIS)

    Humid-air and aqueous general and pitting corrosion models (including their uncertainties) for the carbon steel outer containment barrier were developed using the corrosion data from literature for a suite of cast irons and carbon steels which have similar corrosion behaviors to the outer barrier material. The corrosion data include the potential effects of various chemical species present in the testing environments. The atmospheric corrosion data also embed any effects of cyclic wetting and drying and salts that may form on the corroding specimen surface. The humid-air and aqueous general corrosion models are consistent in that the predicted humid-air general corrosion rates at relative humidities between 85 and 100% RH are close to the predicted aqueous general corrosion rates. Using the expected values of the model parameters, the model predicts that aqueous pitting corrosion is the most likely failure mode for the carbon steel outer barrier, and an earliest failure (or initial pit penetration) of the 100-mm thick barrier may occur as early as about 500 years if it is exposed continuously to an aqueous condition at between 60 and 70 degrees C

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

    OpenAIRE

    Angeliki Lekatou; Athanasios K. Sfikas; Christina Petsa; Alexandros E. Karantzalis

    2016-01-01

    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 ...

  18. The corrosion behavior of Alloy 52 weld metal in cyclic hydrogenated and oxygenated water chemistry in high temperature aqueous environment

    International Nuclear Information System (INIS)

    Highlights: • Ecorr and film resistance in DO and DH periods differ largely. • Oxide film shows two types of semi conductivity in different potential ranges. • Electric and electrochemical properties are changeable during chemical fatigue. • The morphology and composition of the oxide film are unchangeable. - Abstract: The corrosion behavior of Alloy 52 weld metal in cyclic hydrogenated and oxygenated water chemistry in high temperature water is studied by in situ monitoring corrosion potential (Ecorr), contact electric resistance (CER) and electrochemical impedance measurements (EIS), and ex situ scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. The Ecorr and film resistance show large change when the environment is changed from hydrogenated water to oxygenated water and changeable with changing environment while the morphology and composition only show obvious distinction in the first cycle. The main factor controlling the electric/electrochemical properties of the oxide film is Ecorr

  19. Corrosion behavior of aluminum exposed to a biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Ballote, L.; Maldonado-Lopez, L. [Departamento de Fisica Aplicada, CINVESTAV-IPN, Merida Yucatan, 97310 (Mexico); Lopez-Sansores, J.F. [Facultad de Quimica, UADY, Merida Yucatan, 97310 (Mexico); Garfias-Mesias, L.F. [Corrosion and Materials Technology Laboratory, DNV/CCT, Dublin, Ohio, 43017 (United States)

    2009-01-15

    Aluminum was exposed to biodiesel with different levels of contaminants and impurities, and its corrosion behavior was evaluated by conventional electrochemical techniques. It was found that the corrosion behavior of aluminum in biodiesel contaminated with alkalis is similar to the corrosion behavior of aluminum in aqueous solutions. In addition, it was demonstrated that corrosion of aluminum can be used as a quantitative indication of the biodiesel purity. (author)

  20. The corrosion behavior of Alloy 52 weld metal in cyclic hydrogenated and oxygenated water chemistry in high temperature aqueous environment

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jian, E-mail: xujian@fri.niche.tohoku.ac.jp; Shoji, Tetsuo

    2015-06-15

    Highlights: • E{sub corr} and film resistance in DO and DH periods differ largely. • Oxide film shows two types of semi conductivity in different potential ranges. • Electric and electrochemical properties are changeable during chemical fatigue. • The morphology and composition of the oxide film are unchangeable. - Abstract: The corrosion behavior of Alloy 52 weld metal in cyclic hydrogenated and oxygenated water chemistry in high temperature water is studied by in situ monitoring corrosion potential (E{sub corr}), contact electric resistance (CER) and electrochemical impedance measurements (EIS), and ex situ scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. The E{sub corr} and film resistance show large change when the environment is changed from hydrogenated water to oxygenated water and changeable with changing environment while the morphology and composition only show obvious distinction in the first cycle. The main factor controlling the electric/electrochemical properties of the oxide film is E{sub corr}.

  1. Corrosion resistance of amorphous and crystalline Pd40Ni40P20 alloys in aqueous solutions

    DEFF Research Database (Denmark)

    Wu, Y.F.; Chiang, Wen-Chi; Chu, J.; Nieh, T.G.; Kawamura, Y.; Wu, J.K.

    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 Pd40Ni40P...

  2. Electrochemical preparation of NiAl intermetallic compound from solid oxides in molten CaCl2 and its corrosion behaviors in NaCl aqueous solution

    International Nuclear Information System (INIS)

    Highlights: ► Stoichiometric NiAl powder was prepared by one-step electrolysis of solid NiO–NiAl2O4 in molten CaCl2. ► The energy consumption was as low as 6.1 kWh (kg-NiAl)−1. ► Uniform distribution and co-reduction of Ni and Al oxide played key role for Al retaining. ► Electrolytic NiAl powder was made into dense NiAl rod by spark plasma sintering (SPS). ► Obtained NiAl rod was self-passivated in NaCl solution and show very high corrosion resistance. - Abstract: Nickel aluminide powders were prepared by direct electrochemical reduction of solid mixture of NiO–NiAl2O4 (Ni:Al = 1:1 in mol) precursor in molten CaCl2 at 850 °C. The reduction process of the solid oxide cathode was investigated by analyzing the intermediate products using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It reveals that nickel is preferentially reduced and it benefits to prevent aluminum leaving from the cathode. The products obtained at the constant cell voltage electrolysis of 3.0 V for more than 4 h were stoichiometric NiAl. The energy consumption could be as low as 6.1 kWh (kg-NiAl)−1 based on the applied cell voltage and the consumed electrolysis charge. Furthermore, the NiAl powders were made into a dense rod by spark plasma sintering (SPS) technique. The corrosion behaviors of the NiAl rod in 0.5 mol L−1 NaCl aqueous solution at room temperature were investigated by polarization curve and ac impedance measurements. It was found that the NiAl rod had satisfactory anti-corrosion ability in the solution.

  3. Electrochemical preparation of NiAl intermetallic compound from solid oxides in molten CaCl{sub 2} and its corrosion behaviors in NaCl aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Yin Huayi; Yu Tang; Tang Diyong; Ruan Xuefeng; Zhu Hua [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Wang Dihua, E-mail: wangdh@whu.edu.cn [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Stoichiometric NiAl powder was prepared by one-step electrolysis of solid NiO-NiAl{sub 2}O{sub 4} in molten CaCl{sub 2}. Black-Right-Pointing-Pointer The energy consumption was as low as 6.1 kWh (kg-NiAl){sup -1}. Black-Right-Pointing-Pointer Uniform distribution and co-reduction of Ni and Al oxide played key role for Al retaining. Black-Right-Pointing-Pointer Electrolytic NiAl powder was made into dense NiAl rod by spark plasma sintering (SPS). Black-Right-Pointing-Pointer Obtained NiAl rod was self-passivated in NaCl solution and show very high corrosion resistance. - Abstract: Nickel aluminide powders were prepared by direct electrochemical reduction of solid mixture of NiO-NiAl{sub 2}O{sub 4} (Ni:Al = 1:1 in mol) precursor in molten CaCl{sub 2} at 850 Degree-Sign C. The reduction process of the solid oxide cathode was investigated by analyzing the intermediate products using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It reveals that nickel is preferentially reduced and it benefits to prevent aluminum leaving from the cathode. The products obtained at the constant cell voltage electrolysis of 3.0 V for more than 4 h were stoichiometric NiAl. The energy consumption could be as low as 6.1 kWh (kg-NiAl){sup -1} based on the applied cell voltage and the consumed electrolysis charge. Furthermore, the NiAl powders were made into a dense rod by spark plasma sintering (SPS) technique. The corrosion behaviors of the NiAl rod in 0.5 mol L{sup -1} NaCl aqueous solution at room temperature were investigated by polarization curve and ac impedance measurements. It was found that the NiAl rod had satisfactory anti-corrosion ability in the solution.

  4. 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)

    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

  5. Corrosion and Serration Behaviors of TiZr0.5NbCr0.5VxMoy High Entropy Alloys in Aqueous Environments

    OpenAIRE

    Jiemin Li; Xiao Yang; Ruanli Zhu; Yong Zhang

    2014-01-01

    The corrosion and serration behaviors of TiZr0.5NbCr0.5, TiZr0.5NbCr0.5V and TiZr0.5NbCr0.5Mo high entropy alloys (HEAs) in NaCl and H2SO4 solutions were studied by potentiodynamic polarizations (PP) and immersion tests. The results show that all the alloys display excellent corrosion resistance no matter in NaCl solution or in H2SO4 solution. The additions of V and Mo increase the pitting corrosion resistance for the three alloys in NaCl solution slightly and greatly improve the corrosion r...

  6. The Effect of Microwaves on Aqueous Corrosion of Glass

    OpenAIRE

    Lynch, Matthew Earl

    2006-01-01

    Glass corrodes in aqueous environments. The corrosion process is well-understood for many circumstances involving long periods of time at room temperature as well as processes that involve conventional heating, but the effect of microwave energy on glass corrosion has never been fully investigated. It was suspected that microwaves may alter or accelerate the aqueous corrosion processes that occur in glass which contribute to migration into foods or other materials. Lithium disilicate (Li2O...

  7. Corrosion behavior of bulk metallic glass Pr60Fe30-xTM xAl10 in NaCl aqueous solution

    International Nuclear Information System (INIS)

    In this paper, Mn, Ni, Cu and Ti were selected as the partial substitution elements for Fe to produce Pr60Fe30-xTM xAl10 (TM = Mn, Ni, Cu, Ti; x = 0, 5 at.%) quaternary bulk metallic glasses (BMGs) by copper mold casting. The microstructure of samples was characterized by X-ray diffraction (XRD) and the effects of substitution elements on glass forming ability (GFA), electrochemical corrosion behavior in 3.5 wt.% NaCl solution were investigated by differential scanning calorimetry (DSC), potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) techniques. The thermal parameters (e.g. T x/T l, γ, G s, etc.) deduced from DSC indicated that all the samples possessed an amorphous phase and had a high GFA, the GFA of the samples ranks from high to low in the order: Pr60Fe25Mn5Al10 > Pr60Fe30Al10 > Pr60Fe25Ni5Al10 > Pr60Fe25Ti5Al10 > Pr60Fe25Cu5Al10 and the potentiodynamic polarization data analysis shows that the corrosion resistance ability ranks: Pr60Fe25Mn5Al10 60Fe30Al10 60Fe25Ni5Al10 60Fe25Cu5Al10 60Fe25Ti5Al10, which agrees well with that of the EIS data. In the case of the Pr-based BMGs, the GFA has not a correlation with the corrosion resistance, however the chemical composition is the dominating factor controlling the relative corrosion resistance

  8. Corrosion penetration monitoring of advanced ceramics in hot aqueous fluids

    OpenAIRE

    Nickel, Klaus G; Björn Seipel

    2004-01-01

    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...

  9. 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.

  10. Corrosion behaviors and effects of corrosion products of plasma electrolytic oxidation coated AZ31 magnesium alloy under the salt spray corrosion test

    Science.gov (United States)

    Wang, Yan; Huang, Zhiquan; Yan, Qin; Liu, Chen; Liu, Peng; Zhang, Yi; Guo, Changhong; Jiang, Guirong; Shen, Dejiu

    2016-08-01

    The effects of corrosion products on corrosion behaviors of AZ31 magnesium alloy with a plasma electrolytic oxidation (PEO) coating were investigated under the salt spray corrosion test (SSCT). The surface morphology, cross-sectional microstructure, chemical and phase compositions of the PEO coating were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD), respectively. Further, the corrosion process of the samples under the SSCT was examined in a non-aqueous electrolyte (methanol) using electrochemical impedance spectroscopy (EIS) coupled with equivalent circuit. The results show that the inner layer of the coating was destroyed firstly and the corrosion products have significant effects on the corrosion behaviors of the coating. The results above are discussed and an electrochemical corrosion model is proposed in the paper.

  11. Hojalata: Evaluación de su Comportamiento frente a la Corrosión en Medios Acuosos Tinplate: Evaluation of its Corrosion Behavior in Aqueous Media

    Directory of Open Access Journals (Sweden)

    José D Culcasi

    2010-01-01

    Full Text Available Las primeras etapas del deterioro de chapas comerciales de hojalata expuestas a distintas soluciones salinas fueron estudiadas mediante técnicas electroquímicas y de análisis de superficie complementadas por microscopia óptica y electrónica de barrido. Sus resultados fueron analizados e interpretados utilizando modelos capaces de describir adecuadamente la degradación metálica de interfaces tan complejas como reactivas. Se concluyó que: 1 el deterioro de la superficie metálica ocurre mayormente durante las primeras 24 horas de inmersión, alcanzándose luego un comportamiento relativamente estable y reproducible con independencia del medio utilizado; 2 excepto en las soluciones “buffer” basadas en bórax o carbonato donde los escasos productos de corrosión aportaron un efecto protector, en los restantes medios tales productos fueron, en general variantes no protectoras de un oxihidróxido de hierro; y 3 estos resultados coinciden con las velocidades de corrosión determinadas electroquímicamente y, por ende, con el lapso de vida útil del recubrimiento.The first deterioration steps suffered by commercially available tinplate sheets exposed to different saline solutions were studied using electrochemical and surface analysis techniques, as well as optical and electronic scanning microscopy. Their results were analyzed and interpreted utilizing models able to adequately describe the degradation of those as complex as reactive metallic interfaces. It was concluded that: 1 independently of the medium, the main degradation of the metallic surface takes place within the first 24h immersion, but then its behavior is relatively stable and reproducible; 2 except in the buffer solutions based on borax or carbonate where the scarce corrosion products provided a protective effect, in the other electrolyte medium such products were, in general, a variety of non-protective iron oxyhydroxides; and 3 these results are in agreement with the

  12. Aqueous corrosion behaviour of ion-implanted metals

    International Nuclear Information System (INIS)

    We can now look back at 10 years of application of ion beams in corrosion studies. Therefore, after the introduction, we first attempt to give an overview of what has been accomplished during this period in the field of aqueous corrosion, with emphasis on developments in more recent years. Then we present a more detailed discussion of some particular examples of research which make use of different types of corrosion protection mechanism as well as applications of different types of ion beam technique to metal surfaces. These examples include the application of ion beam mixing and ion-beam-assisted vapour deposition to (i) the prevention of localized corrosion, (ii) the reduction of hydrogen uptake by metals (the formation of 'migration barriers'), (iii) corrosion protection by means of ion-beam-mixed monolayers and multilayers of aluminium and boron and (iv) ion-beam-modified carbon layers and their influence on the corrosion of mild steel. Following these examples, we attempt to deduce recommendations for the future application of ion beams in corrosion science. (orig.)

  13. 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)

    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.

  14. Corrosion product behavior in VVER secondary systems

    International Nuclear Information System (INIS)

    Accumulation of corrosion products lead to some problems during long-term operation of VVER plants, such as secondary system component degradation including crud-induced local corrosion and corrosion cracking. Corrosion sludge and deposit removal from steam generators and other equipment is costly and time-consuming and leads to additional waste production. This problem is vital in the case of plant life extension. Appropriate solutions of the problem could be developed based on both Russian and international experience of the VVER fleet. Recommendations on how to mitigate corrosion product accumulation in VVER secondary systems were developed based on comparative analysis of available long-term data on corrosion product behavior in all the operating VVER plants, such as the following: Sludge and deposit accumulation in inner surfaces of secondary piping and components; Corrosion rate measurements using in-situ specimen testing at operated VVER plants; Efficiency of corrosion product removal from secondary system water by means of condensate polishers and steam generator blowdown cleanup systems; Sludge and deposit removal from steam generators during chemical cleaning; Secondary piping and components conservation efficiency during long outages. Comparative data analysis of corrosion product behavior has shown different corrosion product accumulation rates in Novovoronezh, Kola, Kalinin, Balakovo and Rostov NPPs. The said difference is due to different design and operation peculiarities. (author)

  15. Potassium sorbate-A new aqueous copper corrosion inhibitor

    Energy Technology Data Exchange (ETDEWEB)

    Abelev, Esta [Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Starosvetsky, David [Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Ein-Eli, Yair [Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel)]. E-mail: eineli@tx.technion.ac.il

    2007-01-01

    This work presents the novel nature of 2,4-hexadienoic acid potassium salt (potassium sorbate (KCH{sub 3}CH=CHCH=CHCO{sub 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.

  16. Monitoring corrosion and chemistry phenomena in supercritical aqueous systems

    International Nuclear Information System (INIS)

    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

  17. The corrosion of carbon steel in aqueous lithium hydroxide under a hydrogen blanket

    International Nuclear Information System (INIS)

    The corrosion behavior of carbon steel in 3 and 5 mol/L aqueous solutions of lithium hydroxide at 95 degrees C under a hydrogen atmosphere was investigated in immersion tests lasting ten days. Corrosion rates were determined by wight loss, and the corrosion products were characterized by bulk chemical analysis, by light and electron microscopy, and by powder X-ray diffraction. Corrosion was uniform and the corrosion rates were moderately high (0.42 mm/y in 3 mol/L and 0.56 mm/y in 5 mol/L). The corrosion products consisted of a mixture of well-formed, octahedral crystals, and poorly crystallized masses and spherules that formed by precipitation from solution. These products formed a scale on the metal surface that continually sloughed off and afforded only minor protection. Both phases were identified as lithium-iron oxides, each possessing a disordered, non-stoichiometric structure. The predominant phase was a magnetic spinel LiFe508 and the minor phase was LiFe02. A corrosion mechanism is outlined. (2 figs., 5 tabs., 20 refs.)

  18. The corrosion behavior of DWPF glasses

    International Nuclear Information System (INIS)

    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

  19. Effect of silty sand in formation water on CO2 corrosion behavior of carbon steel

    Science.gov (United States)

    Liu, Wei; Dou, Juanjuan; Lu, Songle; Zhang, Peng; Zhao, Qinghe

    2016-03-01

    Corrosion behavior of carbon steel in CO2 aqueous environment containing silty sand was investigated using corrosion mass loss method, scanning electron microscopy (SEM), energy diffraction spectrum (EDS), and various electrochemical measurements. The results show that the corrosion rate of carbon steel was obviously reduced due to the existence of silty sand. Silty sand promoted the rapid heterogeneous nucleation of corrosion product FeCO3 and simultaneously decreased its grains growth. Silty sand mixed with corrosion product to form the outer layer of corrosion scale with high compactness, blocking the transport of ferrous ions and leading to the formation of the inner layer of corrosion scale without silty sand. The existence of silty sand in the outer layer of corrosion scale inhibited anodic and cathodic currents.

  20. Passive Corrosion Behavior of Alloy 22

    International Nuclear Information System (INIS)

    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

  1. 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.

  2. 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. PMID:9713683

  3. Corrosion Behavior of Extruded near Eutectic Al-Si-Mg and 6063 Alloys

    Institute of Scientific and Technical Information of China (English)

    Yuna Wu; Hengcheng Liao

    2013-01-01

    In this work,a comparison study on corrosion behavior of extruded near eutectic Al-12.3%Si-0.26%Mg and 6063 alloys has been carried out by mass loss test in 4% H2SO4 aqueous solution in the open air and potentiodynamic polarization test in 3.5 wt.% NaCl aqueous solution.Results indicate that the corrosion resistance of the near eutectic Al-Si-Mg alloy is less than that of 6063 alloy.Macro/microscopy and scanning electron microscopy results clearly show the difference of the corrosion progress of these two alloys in 4% H2SO4 aqueous solution.The corrosion type of 6063 alloy is pitting corrosion.The Mg2Si and AlFeSi particles and surface defects act as nucleation sites for pitting,and the amount and distribution of them have a significant effect on the pitting behavior.For the near eutectic alloy,there are two types of corrosion cells.One is between the extruded primary α-Al and the eutectic,the other is between the eutectic Al and eutectic Si particles.Combination of these two types of corrosion cells leads to a lower corrosion resistance,a higher mass loss of the near eutectic alloy compared with 6063 alloy,and the formation of the paralleling corroded grooves.

  4. Corrosion behavior of magnesium and magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    I.M.Baghni; WU Yin-shun(吴荫顺); LI Jiu-qing(李久青); ZHANG Wei(张巍)

    2004-01-01

    The automotive industry has crossed the threshold from using magnesium alloys in interior applications such as instrument panels and steering wheels to unprotected environment such as oil pan, cylinder head and wheels. The expanding territory of magnesium leads to new challenges: mainly environmental degradation of the alloys used and how they can be protected. The present critical review is aimed at understanding the corrosion behavior of magnesium and magnesium alloys in industrial and marine environments, and the effect of microstructure, additive elements and inhibitors on the corrosion mechanism.

  5. Corrosion behavior of vanadium alloys in flowing lithium

    International Nuclear Information System (INIS)

    Corrosion data are presented for several vanadium alloys exposed to flowing lithium at 427, 482 and 5380C. The corrosion behavior was evaluated by measuring weight change. Metallographic results and data on the nonmetallic element transfer in lithium-exposed specimens are also presented. The influence of alloy composition and exposure conditions on the corrosion behavior of vanadium alloys is discussed. (orig.)

  6. Corrosion behavior of WE54 magnesium alloy in 3.5%NaCl solution

    Institute of Scientific and Technical Information of China (English)

    LI Zhuo-qun; SHAN Da-yong; CHEN Rong-shi; KE Wei; HAN En-hou

    2006-01-01

    The corrosion behavior of WE54 magnesium alloy was investigated in 3.5%NaCl aqueous solution. The electrochemical study shows that the value of corrosion potential of WE54 magnesium was -1.8V(vs SCE). In the initial stage of immersion, a kind of visible thin film, which has the appearance of artificial conversion coating by microscopy observation, formed on the surface of WE54 alloy. Through the comparison of corrosion behavior between WE54 and AZ91D, it is shown that the value of corrosion potential of WE54 is approximately 200 mV lower than that of AZ91D, and the corrosion rate of WE54 was one order smaller than that of AZ91D. After 72 h constant immersion and corrosion products removal, deeper grooves along grain boundaries was revealed but lighter corrosion was apparent on the matrix of WE54 alloy. As far as AZ91D alloy was concerned, severe localized corrosion was dominant and network-bone-like structure was remained.

  7. 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.

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

    International Nuclear Information System (INIS)

    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

  9. Experimental study on corrosion behavior of carbon steel in buffer material-I. Behavior of corrosion propagation based on the results of immersion tests for 10 years

    International Nuclear Information System (INIS)

    The deep underground environment where overpacks will be emplaced is expected to be anaerobic environment. It is necessary to understand the corrosion behavior of carbon steel in such environment for the assessment of corrosion lifetime of carbon steel overpacks. In this study, immersion tests of carbon steel were carried out in buffer material for 10 years duration in nitrogen atmosphere in which oxygen gas concentration was controlled to less than 1 ppm. Synthetic sea water and aqueous solution containing bicarbonate ion and chloride ion were selected as the test solution. The effects of temperature, bentonite purity and atmosphere on the corrosion behavior were investigated. The amount of corrosion of carbon steel was estimated from the weight loss of the test coupon, and its change with time was investigated. The experimental results were summarised as follows; The corrosion rates were decreased with time in every test case, and as the corrosion rate at early stage of immersion was larger, the corrosion propagation was more suppressed after a long term. The influence of purity of bentonite and the atmosphere of gas phase on the behavior of corrosion propagation was small. The amount of corrosion in high carbonate concentration was smaller than those of other test conditions throughout the test periods. The change of corrosion depth, Y with time, X was approximated by power law equation, Y=AXB. The parameter A and B in synthetic sea water system was expressed as a function of dry density of buffer material, ρ(g/cm3), sand mixing ratio, r(0 ≤ r ≤ 1) and temperature, T(K). The corrosion rates calculated from the gradient of the change of the average corrosion depth between 1 to 10 years were in the range of 0.055 - 1.4 μm/y. It was confirmed that the corrosion rate of 10 μm/y used in the past lifetime assessment of overpack was sufficiently conservative in comparison with laboratory test data for 10 years and natural analogue data. (author)

  10. 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)

  11. Ecological and corrosion behavior of depleted uranium

    Directory of Open Access Journals (Sweden)

    Stojanović Mirjana D.

    2015-01-01

    Full Text Available Environmental pollution with radionuclides, particularly uranium and its decay products is a serious global problem. The current scientific studies estimated that the contamination originating from TENORM, caused by nuclear and non-nuclear technologies, has significantly increased natural level of radioactivity in the last thirty years. During the last decades all the more were talking about the "new pollutant" - depleted uranium (DU, which has been used in anti-tank penetrators because of its high density, penetration and pyrophoric properties. It is estimated that during the Gulf War, the war in Bosnia and Yugoslavia and during the invasion of Iraq, 1.4 million missiles with depleted uranium was fired. During the NATO aggression against the ex Yugoslavia in 1999., 112 locations in Kosovo and Metohija, 12 locations in southern Serbia and two locations in Montenegro were bombed. On this occasion, approximately 10 tons of depleted uranium were entered into the environment, mainly on land, where the degree of contamination ranged from 200 Bq / kg to 235 000 Bq/kg, which is up to 1000 times higher than the natural level. Fourteen years ago there was very little information about the behavior of ecological systems damaged by DU penetrators fired. Today, unfortunately, we are increasingly faced with the ―invisible threat" of depleted uranium, which has a strong radioactive and hemotoxic impact on human health. Present paper provides a detailed overview of the current understanding of corrosion and corrosion behavior of DU and environmental factors that control corrosion, together with indicators of environmental impact in order to highlight areas that need further attention in developing remediation programs.

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

    International Nuclear Information System (INIS)

    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

  13. Evaluation of Corrosion Behavior with Various Corrosion Inhibitors in Closed Cooling Water System

    International Nuclear Information System (INIS)

    The Closed Cooling Water (CCW) piping consists of carbon steel in many CCW systems. CCW can have a falling-off in quality of the system by corrosion, microbial growth, fouling to prevent corrosion, we must accurately evaluate influence of an inhibitor in CCW system. In the case of CCW of some domestic nuclear power plants, during overhaul period, saturation of ion exchange resin caused by an inhibitor which has high conductivity for an increase in radiation exposure and radioactive waste. Corrosion inhibition in recirculated cooling water systems historically depended on the oxidizing inhibitors. In most cases, carbon steel corrosion control in CCW systems is achieved by adding corrosion inhibitor chemicals. In nuclear plants, these inhibitors have included chromates, nitrites, molybdates, hydrazine, and silicate. The objective of this study is to evaluate the corrosion behavior of structural materials according to corrosion inhibitor

  14. Corrosion Behavior of Aluminum-Steel Weld-Brazing Joint

    Science.gov (United States)

    Shi, Yu; Li, Jie; Zhang, Gang; Huang, Jiankang; Gu, Yufen

    2016-05-01

    Dissimilar metals of 1060 aluminum and galvanized steel were joined with a lap joint by pulsed double-electrode gas metal arc weld brazing with aluminum-magnesium and aluminum-silicon filler metals. The corrosion behavior of the weld joints was investigated with immersion corrosion and electrochemical corrosion tests, and the corrosion morphology of the joints was analyzed with scanning electron microscopy (SEM). Galvanic corrosion was found to occur when the samples were immersed in corrosive media, and the corrosion rate of joints was increased with increased heat input of the workpiece. Comparison of the corrosion properties of weld joints with different filler wires indicated that the corrosion rate of weld joints with aluminum-silicon filler wire was larger than that of weld joints with aluminum-magnesium filler wire. Results also showed that the zinc-rich zone of weld joints was prone to corrosion. The corrosion behavior of zinc-rich zone was analyzed with SEM equipped with an energy-dispersive x-ray spectroscopy analysis system based on the test results.

  15. Corrosion Behavior of Aluminum-Steel Weld-Brazing Joint

    Science.gov (United States)

    Shi, Yu; Li, Jie; Zhang, Gang; Huang, Jiankang; Gu, Yufen

    2016-03-01

    Dissimilar metals of 1060 aluminum and galvanized steel were joined with a lap joint by pulsed double-electrode gas metal arc weld brazing with aluminum-magnesium and aluminum-silicon filler metals. The corrosion behavior of the weld joints was investigated with immersion corrosion and electrochemical corrosion tests, and the corrosion morphology of the joints was analyzed with scanning electron microscopy (SEM). Galvanic corrosion was found to occur when the samples were immersed in corrosive media, and the corrosion rate of joints was increased with increased heat input of the workpiece. Comparison of the corrosion properties of weld joints with different filler wires indicated that the corrosion rate of weld joints with aluminum-silicon filler wire was larger than that of weld joints with aluminum-magnesium filler wire. Results also showed that the zinc-rich zone of weld joints was prone to corrosion. The corrosion behavior of zinc-rich zone was analyzed with SEM equipped with an energy-dispersive x-ray spectroscopy analysis system based on the test results.

  16. 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

  17. Effect of extrusion on corrosion behavior and corrosion mechanism of Mg-Y alloy

    Institute of Scientific and Technical Information of China (English)

    XU Hong; ZHANG Xin; ZHANG Kui; SHI Yang; REN Jiping

    2016-01-01

    The influences of the hot extrusion process on the microstructure, corrosion behavior and corrosion mechanism for Mg-Y magnesium alloy were studied by means of the microstructure observation, weight loss test, electrochemical test and corrosion mor-phology test. The results showed that with increasing of the extrusion ratio, the shear flow line on the vertical section of the extruded alloy increased, the shear bands parallel lines became more clearly visible, and a large number of fine equiaxed grains distributed in parallel with the flow lines. The open circuit potential had a certain degree of improvement after extrusion, the open circuit potential increased with increment of extrusion ratio, and the corrosion potential of the vertical section was higher than that of the same alloy in the same compression ratio. The shift rate of the corrosion potential relatively became larger with increasing of the extrusion ratio, and the cathode corrosion current corresponding to the branch migration shifted to the positive direction. The high frequency capaci-tive arc increased with increment of the extrusion ratio, and the radius of capacitive arc of the vertical section was slightly larger than that of the transverse section. The corrosion morphologies of Mg-0.25Y alloy were uniform corrosion, and the corrosion morpholo-gies of Mg-(2.5, 5, 8 and 15) were the pitting corrosion and the small range, deep depth localized corrosion.

  18. Corrosion behavior of carbon steels under tuff repository environmental conditions

    International Nuclear Information System (INIS)

    Carbon steels may be used for borehole liners in a potential high-level nuclear waste repository in tuff in Nevada. Borehole liners are needed to facilitate emplacement of the waste packages and to facilitate retrieval of the packages, if required. Corrosion rates of low carbon structural steels AISI 1020 and ASTM A-36 were determined in J-13 well water and in saturated steam at 1000C. Tests were conducted in air-sparged J-13 water to attain more oxidizing conditions representative of irradiated aqueous environments. A limited number of irradiation corrosion and stress corrosion tests were performed. Chromium-molybdenum alloy steels and cast irons were also tested. These materials showed lower general corrosion but were susceptible to stress corrosion cracking when welded. 4 references, 4 tables

  19. Studies on the aqueous corrosion of zircaloy-2 prefilmed by various methods

    International Nuclear Information System (INIS)

    The aqueous corrosion of zircaloy-2 prefilmed by different methods has been carried out in aqueous media at 350deg C and saturation pressure using autoclaves. The prefilming treatments include, oxidation in steam at 400deg C, oxidation in air at 400deg C, anodization in 1% H2SO4 and 1% KOH at room temperature to weight-gains corresponding to thin film region (2 to 5 mg/dm2). It is seen that prefilming by anodization in 1% KOH resulted in lower corrosion and hydrogen pick-up rates as compared to other prefilming methods as well as to plain zircaloy-2. (auth.)

  20. Corrosion behavior of tantalum and its nitride in alkali solution

    Institute of Scientific and Technical Information of China (English)

    ZHANG Deyuan; LIN Qin; FEI Qinyong; ZHAO Haomin; KANG Guangyu; GENG Man

    2003-01-01

    The corrosion behavior of tantalum and its nitrides in stirring NaOH solutions was researched by potenfiostatic method, cyclic voltammetry and XPS. The results showed that the corrosion products were composed of Ta2O5 and NaTaO3.The corrosion reaction formula of tantalum and its nitrides was written according to cyclic volt-ampere curves. The electric charge transfer coefficient and the electric charge transfer number were calculated.

  1. Plutonium silicate alteration phases produced by aqueous corrosion of borosilicate glass

    International Nuclear Information System (INIS)

    Borosilicate glasses loaded with ∼10 wt % plutonium were found to produce plutonium-silicate alteration phases upon aqueous corrosion under a range of conditions. The phases observed were generally rich in lanthanide (Ln) elements and were related to the lanthanide orthosilicate phases of the monoclinic Ln2SiO5 type. The composition of the phases was variable regarding [Ln]/[Pu] ratio, depending upon type of corrosion test and on the location within the alteration layer. The formation of these phases likely has implications for the incorporation of plutonium into silicate alteration phases during corrosion of titanate ceramics, high-level waste glasses, and spent nuclear fuel

  2. Contact corrosion of aluminum and its alloys in aqueous environment of nuclear facilities

    International Nuclear Information System (INIS)

    The paper presents processes occurring during contact corrosion of structural materials of nuclear facilities, namely aluminium, its alloy SAV-1 with zirconium alloy E110 and stainless steel Cr18ni10ti. The results of electrochemical and autoclave testing of examined contact pairs showed that in all cases the anode is aluminum (or SAV-1), which oxidizes more intensively in comparison with E110 and Cr18ni10ti. During of aluminum and SAV-1 oxidation in an aqueous environment, corrosion products dissolve in the corrosion environment. Pre- oxidation of cathode material (E110) to oxide film thickness 1-1.5 microns virtually eliminates galvanic corrosion component of SAV-1 in the contact pair with E110, which is confirmed by the measurement results of corrosion current density and other indicators characterizing the reliability of the elements and safety of the entire facility

  3. Corrosion behavior of Ti–39Nb alloy for dentistry

    International Nuclear Information System (INIS)

    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

  4. 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.

  5. Corrosion behaviour of aluminium plates in aqueous medium

    International Nuclear Information System (INIS)

    The process of corrosion concerning the aluminium 1050 plate was studied at room temperatures, 45 and 600C 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 600C the samples were covered with bayerita, the quantity of oxide formed at 450C being higher than at 600C. 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)

  6. 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. PMID:9228844

  7. Corrosion effects of the interreaction of 6061 aluminum with aqueous mixtures and solutions of selected HE`s

    Energy Technology Data Exchange (ETDEWEB)

    Clink, G.L. [Sandia Labs., Albuquerque, NM (United States)

    1971-12-31

    The behavior of several selected HE and HE-component materials in aqueous media in contact with 6061 aluminum has been studied via conductance, cathodic tendencies (cell EMF measurements), pH, and visual analysis (photomicrographs) of the 6061 electrodes and media contacts rods. Addition of orthophthalic acid (OPA) to the media was also made to study potential corrosive effects possibly due to some breakdown of the polyphthalate systems in contact with these materials. Overall assessment of data is not made at this time due to the interrelationship of these data with data which should be obtained from unfinished portions of the study.

  8. Corrosion behavior of Cu during graphene growth by CVD

    International Nuclear Information System (INIS)

    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

  9. Corrosion Behavior of Titanium in Artificial Saliva by Lactic Acid

    Directory of Open Access Journals (Sweden)

    Qing Qu

    2014-07-01

    Full Text Available As one of the main products produced by oral microorganisms, the role of lactic acid in the corrosion of titanium is very important. In this study, the corrosion behavior of titanium in artificial saliva with and without lactic acid were investigated by open-circuit potentials (OCPs, polarization curves and electrochemical impedance spectroscopy (EIS. OCP firstly increased with the amount of lactic acid from 0 to 3.2 g/L and then tended to decrease from 3.2 to 5.0 g/L. The corrosion of titanium was distinctly affected by lactic acid, and the corrosion rate increased with increasing the amount of lactic acid. At each concentration of lactic acid, the corrosion rate clearly increased with increasing the immersing time. Results of scanning electron microscopy (SEM also indicated that lactic acid accelerated the pitting corrosion in artificial saliva. A probable mechanism was also proposed to explain the experimental results.

  10. Microbiologically induced corrosion of aluminum alloys in fuel-oil/aqueous system.

    Science.gov (United States)

    Yang, S S; Lin, J Y; Lin, Y T

    1998-09-01

    To investigate the microbiologically induced corrosion of aluminum alloys in fuel-oil/aqueous system, aluminum alloys A356, AA 5052, AA 5083 and AA 6061 were chosen as the test alloys and Cladosporium and several fuel-oil contaminated microbes isolated in Taiwan were used as test organisms. Aluminum alloy AA 5083 in fuel-oil/aqueous system was the most susceptible material for microbial corrosion, then followed by aluminum alloys AA 5052 and A356, and AA 6061 was more resistant to microbial aggression. Mixed culture had high capability of corrosion, then followed by Penicillium sp. AM-F5, Fusarium sp. AM-F1, Pseudomonas aeruginosa AM-B5, Ps. fluorescens AM-B9, C. resinae ATCC 22712, Penicillium sp. AM-F2, Candida sp. AM-Y1 and Ps. aeruginosa AM-B11. From energy dispersive spectrometer analysis, aluminum and magnesium contents decreased in the corrosion area, while chlorine and sulfur contents increased. The major organic acid produced in fuel-oil/aqueous system was acetic acid, and the total organic acids content had a positive correlation with the degree of microbial corrosion. PMID:10496152

  11. Corrosion Behavior of Silicon Carbide/7091 Aluminum Matrix Composites

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Wooseung [Inha Technical College, Incheon (Korea, Republic of)

    2012-04-15

    The effects of volume fraction (15-30%) of SiC particulate reinforcements on the corrosion behavior of SiCp/7091 Al composites in the 3.5% NaCl solution were studied by electrochemical techniques and scanning electron microscopy. The results showed that the amount of SiC particulate reinforcements did not cause much difference in the corrosion behavior of SiCp/7091 Al composites but the corrosion rate was proportional to the amount of SiCp reinforcement. And numerous pits and severe dissolution of the matrix was observed probably due to the discontinuities and galvanic effects between Al matrix and SiC reinforcements.

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

    OpenAIRE

    Mohd Mobin; Hina Shabnam

    2011-01-01

    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 ...

  13. Aqueous chloride stress corrosion cracking of titanium - A comparison with environmental hydrogen embrittlement

    Science.gov (United States)

    Nelson, H. G.

    1974-01-01

    The physical characteristics of stress corrosion cracking of titanium in an aqueous chloride environment are compared with those of embrittlement of titanium by a gaseous hydrogen environment in an effort to help contribute to the understanding of the possible role of hydrogen in the complex stress corrosion cracking process. Based on previous studies, the two forms of embrittlement are shown to be similar at low hydrogen pressures (100 N/sq m) but dissimilar at higher hydrogen pressures. In an effort to quantify this comparison, tests were conducted in an aqueous chloride solution using the same material and test techniques as had previously been employed in a gaseous hydrogen environment. The results of these tests strongly support models based on hydrogen as the embrittling species in an aqueous chloride environment.

  14. Corrosion properties of HVOF cermet coatings with bond coats in an aqueous chloride environment

    International Nuclear Information System (INIS)

    WC-17Co coatings with Ni-5Al bonding layers were deposited on Al-7075 by HVOF spraying. The top-coat consisted of layers comprising tungsten carbide particles embedded in a Co(W,C) matrix of varied composition.The coated specimens were subjected to potentiodynamic polarization in 3.5% aqueous NaCl at 25, 35 and 45 deg. C. The coatings exhibited pseudopassivity caused by the oxidation of tungsten, carbon and possibly cobalt. Chronoamperometric measurements indicated that the inhomogeneous binder composition induced active corrosion processes taking place simultaneously with pseudopassivity. Cyclic polarization suggested that the coatings were not susceptible to pit corrosion in the temperature range of 25-45 deg. C. The likely 'critical pitting' temperature of the coatings was 60 deg. C. Higher testing temperatures led to lower corrosion potentials and faster corrosion kinetics

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

    International Nuclear Information System (INIS)

    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)

  16. Effect of geologic repository parameters on aqueous corrosion of nuclear glass

    International Nuclear Information System (INIS)

    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 (SiO2 + Al2O3), and between the initial rate and the (Na2O + Li2O + B2O3) / (SiO2 + Al2O3) 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

  17. Corrosion Behavior of Commercial Magnetic Refrigerant Gadolinium in Water

    Institute of Scientific and Technical Information of China (English)

    Zhang Zeyu; Long Yi; Wen Da; Ye Rongchang; Wan Farong

    2004-01-01

    Gadolinium(Gd) used as magnetic refrigerant always works in water environment.However, its poor corrosion resistance is serious impediment against wider application of Gd.In this paper, the corrosion behavior of two types of commercial Gd ( A, B both are 98.9 at.% pure) with the same oxygen content has been studied.The results show that the corrosion rate of A is 3.226 times higher than that of B in deionized water and 6.039 times in tap water.According to SEM, the different corrosion rate is because of the different distribution of impurity in matrix.In addition,NaOH solution was chosen as inhibitor to prevent Gd from being corroded successfully.No pitting corrosion and weight loss were observed for commercial Gd even after immersion for nearly 2000 h in NaOH solution.

  18. Effect of different Mo contents on tensile and corrosion behaviors of CD4MCU cast duplex stainless steels

    International Nuclear Information System (INIS)

    In the present study, the effect of Mo contents on the microstructure, tensile and corrosion behaviors of as-solutionized CD4MCU cast duplex stainless steel was examined. The polarization test was conducted in 3.5% NaCl +5% H2SO4 aqueous solution for general corrosion resistance and the slow strain rate tests were also conducted in air and 3.5% NaCl+5% H2SO4 aqueous solution to study the Stress Corrosion Cracking (SCC) of the present alloy. A substantial microstructural evolution of CD4MCU cast duplex stainless steel was observed with different Mo contents, which in turn affected the tensile and corrosion behaviors significantly. The beneficial effect of Mo on improving the corrosion and the SCC resistances was largely overwhelmed by this variation of microstructural characteristics. The relationship between the microstructural evolution and the tensile and corrosion behavior of CD4MCU cast duplex stainless steels with different Mo contents was discussed based on the optical and SEM micrographic and fractographic observations

  19. Corrosion behavior of duplex stainless steel in sulphuric acid

    International Nuclear Information System (INIS)

    Duplex stainless steels are alloyed and processed to develop microstructure of roughly equal amounts of ferrite and austenite. Duplex stainless steel constitute a new class of materials because they have balanced amounts of ferrite and austenite. Since they have high content of chromium and molybdenum present, thus they have good corrosion resistance. Their corrosion resistance is double to that of annealed austenitic stainless steels with regard to pitting, crevice corrosion, sulphide stress corrosion, and chloride stress corrosion environments. The corrosion behavior of duplex stainless steel in various concentrations of sulphuric acid was studied. The reactions were carried out by placing the steel specimen in a beaker containing a known concentration of sulphuric acid at room temperature for a definite period. Pits were initiated in duplex stainless steel specimen and the propagation of pits depends upon the concentration of the acid solution in which the sample is in contact. The weight loss for definite period of time were measured and corrosion rates were calculated in millimetres per year. The corrosion rates increases with an increase in acid concentration at room temperature. A comparison of the results obtained from various concentrations of sulphuric acid with the same concentrations of nitric acid is also discussed. (author)

  20. COMPARATIVE CORROSION BEHAVIOR OF TWO PALLADIUM-CONTAINING TITANIUM ALLOYS

    International Nuclear Information System (INIS)

    The ASTM standard B 265 provides the requirements for the chemical composition of titanium (Ti) alloys. It is planned to use corrosion resistant and high strength titanium alloys to fabricate the drip shield at the proposed Yucca Mountain Repository. Titanium grade (Gr) 7 (R52400) and other Ti alloys are currently being characterized for this application. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance. In this article we report results on the comparative short term corrosion behavior of Ti Gr 7 and a Ruthenium (Ru) containing alloy (Ti Gr 33). Ti Gr 33 also contains a small amount of Pd. Limited electrochemical testing such as polarization resistance and cyclic potentiodynamic curves showed that both alloys have a similar corrosion behavior in the tested environments

  1. Comparative Corrosion Behavior of Two Palladium Containing Titanium Alloys

    International Nuclear Information System (INIS)

    The ASTM standard B 265 provides the requirements for the chemical composition of titanium (Ti) alloys. It is planned to use corrosion resistant and high strength titanium alloys to fabricate the drip shield at the proposed Yucca Mountain Repository. Titanium grade (Gr) 7 (R52400) and other Ti alloys are currently being characterized for this application. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance. In this article we report results on the comparative short term corrosion behavior of Ti Gr 7 and a Ruthenium (Ru) containing alloy (Ti Gr 33). Ti Gr 33 also contains a small amount of Pd. Limited electrochemical testing such as polarization resistance and cyclic potentiodynamic curves showed that both alloys have a similar corrosion behavior in the tested environments

  2. COMPARATIVE CORROSION BEHAVIOR OF TWO PALLADIUM CONTAINING TITANIUM ALLOYS

    Energy Technology Data Exchange (ETDEWEB)

    T. Lian, T. Yashiki, T. Nakayama, T. Nakanishi, R. B. Rebak

    2006-07-23

    The ASTM standard B 265 provides the requirements for the chemical composition of titanium (Ti) alloys. It is planned to use corrosion resistant and high strength titanium alloys to fabricate the drip shield at the proposed Yucca Mountain Repository. Titanium grade (Gr) 7 (R52400) and other Ti alloys are currently being characterized for this application. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance. In this article we report results on the comparative short term corrosion behavior of Ti Gr 7 and a Ruthenium (Ru) containing alloy (Ti Gr 33). Ti Gr 33 also contains a small amount of Pd. Limited electrochemical testing such as polarization resistance and cyclic potentiodynamic curves showed that both alloys have a similar corrosion behavior in the tested environments.

  3. Magnetite dissolution and corrosion behavior in high temperature EDTA solvents

    International Nuclear Information System (INIS)

    The effect of temperature on magnetite dissolution and corrosion behavior was evaluated in ethylenediaminetetraacetic acid (EDTA)-based solvents for iron oxide chemical cleaning of nuclear steam generators at temperatures ranging from 93 to 150 deg. C. Magnetite dissolution was drastically accelerated as the temperature was raised to 150 deg. C, while the amount of corrosion was controlled well within an allowable limit. Periodic venting and excessive EDTA concentration in the solvents were expected to be very effective in dissolving hard tube sheet sludge piles. The linear polarization (LP) method was also suitable to monitor the changes of corrosion rates and process conditions such as venting

  4. Corrosion Behavior of Titanium in Artificial Saliva by Lactic Acid

    OpenAIRE

    Qing Qu; Lei Wang; Yajun Chen; Lei Li; Yue He; Zhongtao Ding

    2014-01-01

    As one of the main products produced by oral microorganisms, the role of lactic acid in the corrosion of titanium is very important. In this study, the corrosion behavior of titanium in artificial saliva with and without lactic acid were investigated by open-circuit potentials (OCPs), polarization curves and electrochemical impedance spectroscopy (EIS). OCP firstly increased with the amount of lactic acid from 0 to 3.2 g/L and then tended to decrease from 3.2 to 5.0 g/L. The corrosion of tita...

  5. In vitro corrosion behavior of lingual orthodontic archwires

    OpenAIRE

    Carlos Suárez; Teresa Vilar; Pablo Sevilla; Javier Gil

    2011-01-01

    Objectives. To investigate the in vitro electrochemical corrosive behavior of archwires used in lingual orthodontics and the effects on the phase transition temperatures. Materials and Methods. Six different types of archwires of stainless steel, titanium-molybdenum, nickel-titanium and nickel-titanium-copper were used. Corrosion tests were performed following ISO-standard 10993-15:2000. Differential scanning calorimetry and scanning electron microscopy were used. Results. The stainless steel...

  6. Contribution to the study of uranium dioxide aqueous corrosion mechanisms

    International Nuclear Information System (INIS)

    The corrosion of uranium dioxide by a synthetical ground water has been studied in order to understand the behaviour of nuclear fuels in the hypothesis of a direct storage. An original leaching unit has been carried out in order to control the parameters occurring in the oxidation-dissolution of the uranium dioxide and to condition the leachate (in particular the temperature and the partial pressure of the carbon dioxide). A ground water in equilibrium with the geological enveloping site has been reconstituted from data acquired on the site. The influence of two parameters has been followed: the carbon dioxide carbon pressure and the redox potential. Each experiment has been carried out at 96 C during one month and the time-history of the solutions and of the solids has been studied. In oxidizing conditions, the uranium concentration in solution has been controlled by an U(VI) complex (one oxide, one hydroxide or a carbonate). The possibility of a control by an U(IV) complex (as coffinite, uraninite or uraninite B) has been confirmed in the case of reducing leaching. An original interpretation of the Rutherford backscattering spectra has allowed to describe the decomposition of the samples in a succession of layers of different densities. A very good agreement between the analyses of the solids and those of the solutions has been obtained in the experiments occurring in reducing conditions. Complementary leaching involving solutions containing stable isotopes (deuterium, O18) have revealed the formation of an hydrated layer and the contribution of grain boundaries to the corrosion phenomenon of uranium dioxide. The results of the current hydro-geochemistry study on the uranium Oklo deposit prove the realism of the experiments that have been carried out in the laboratory. (O.M.)

  7. AFM study of steel corrosion in aqueous solutions in concrete

    Directory of Open Access Journals (Sweden)

    Díaz-Benito, B.

    2011-03-01

    Full Text Available Early corrosion stages are studied in carbon steel by means of a solution simulating that contained in concrete pores. Non-carbonated solution contains 5% NaCl. The atomic force microscopy (AFM technique is used to study material performance after different immersion times (up to 48 h. Obtained data are compared to electrochemical ones (corrosion potential and polarization resistance. Analysis of images and roughness evolution along time shows that steel initially tends to reach passivity, although the passive layer rapidly loses its protective character due to chloride attack.

    Este trabajo estudia los primeros estados de la corrosión de un acero al carbono en una disolución que simula la existente en los poros del hormigón, sin carbonatar, con un 5% de NaCl. Para ello, se ha empleado la técnica de microscopía de fuerza atómica (AFM, estudiando el comportamiento del material tras diferentes tiempos de inmersión, hasta 48 h, en la disolución. Estos datos se comparan con datos electroquímicos (potencial de corrosión y resistencia de polarización. El análisis de las imágenes y la evolución de la rugosidad con el tiempo muestran que el acero tiende inicialmente a pasivarse, pero la capa pasiva pierde rápidamente su carácter protector debido al ataque de los cloruros.

  8. Corrosion and mechanical behavior of materials for coal gasification applications

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1980-05-01

    A state-of-the-art review is presented on the corrosion and mechanical behavior of materials at elevated temperatures in coal-gasification environments. The gas atmosphere in coal-conversion processes are, in general, complex mixtures which contain sulfur-bearing components (H/sub 2/S, SO/sub 2/, and COS) as well as oxidants (CO/sub 2//CO and H/sub 2/O/H/sub 2/). The information developed over the last five years clearly shows sulfidation to be the major mode of material degradation in these environments. The corrosion behavior of structural materials in complex gas environments is examined to evaluate the interrelationships between gas chemistry, alloy chemistry, temperature, and pressure. Thermodynamic aspects of high-temperature corrosion processes that pertain to coal conversion are discussed, and kinetic data are used to compare the behavior of different commercial materials of interest. The influence of complex gas environments on the mechanical properties such as tensile, stress-rupture, and impact on selected alloys is presented. The data have been analyzed, wherever possible, to examine the role of environment on the property variation. The results from ongoing programs on char effects on corrosion and on alloy protection via coatings, cladding, and weld overlay are presented. Areas of additional research with particular emphasis on the development of a better understanding of corrosion processes in complex environments and on alloy design for improved corrosion resistance are discussed. 54 references, 65 figures, 24 tables.

  9. Evaluation of stress corrosion cracking in aqueous solution neutron shield of transport/storage cask for spent fuel

    International Nuclear Information System (INIS)

    Experimental evaluation proved that no chloride induced stress corrosion cracking will occur on the metal cask which utilizes propylene glycol aqueous solution as neutron shield. Crevice corrosion, precursor of cracking, occurs at about 0.4V vs. 0.1M-KCl silver silver-chloride reference electrode in aqueous solution with chloride concentration of more than 5 times higher than limit value. On the other hand, the electrochemical potential (ECP) of cask material was 0.08V in air saturated aqueous solution. Since ECP is much smaller than the crevice corrosion potential below which no crevice corrosion is expected, the possibility is very small for chloride induced stress corrosion cracking to occur on the cask. (author)

  10. Galvanic Corrosion between Alloy 690 and Magnetite in Alkaline Aqueous Solutions

    OpenAIRE

    Soon-Hyeok Jeon; Geun-Dong Song; Do Haeng Hur

    2015-01-01

    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 All...

  11. Study on long-term corrosion behavior of high corrosion resistant metal overpack under reducing condition

    International Nuclear Information System (INIS)

    For repository container material of high-level radioactive wastes, titanium, nickel-based alloys, etc. have been investigated as high corrosion resistant metal. Titanium has excellent corrosion resistance under high chloride and oxidizing conditions and has many applications in general industries. However it has a possibility to absorb hydrogen generated by water reduction and cause hydrogen embrittlement under reducing condition of the repository. In this study, experimental investigation was carried out on hydrogen absorption behavior of titanium and influencing factors under reducing condition. In addition, previous studies were searched on the corrosion resistant material other than titanium. (1) Electrochemical acceleration tests of titanium were carried out to apply cathodic electric charge equivalent to the corrosion for 1000 years under reducing condition. The effects of parameters, processing rate, heat treatment conditions, applied stress and solution pH, on the hydrogen absorption rate were evaluated. (2) Sealed ampoule type immersion tests were conducted under reducing condition. Effects of pH on the hydrogen absorption rate were evaluated and furthermore, the surface hydrogen concentration was analyzed. (3) Hydrogen absorption/embrittlement models of titanium overpack were discussed and hydrogen concentration distribution after 1000 years was predicted. (4) Previous studies on corrosion behavior of high corrosion resistant alloys other than titanium were searched and organized. In addition, an investigation was conducted on the selection of waste package materials in the United States. (author)

  12. The effects of radiolysis on the corrosion and stress corrosion behavior of 316 stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Duquette, D.J.; Steiner, D.

    1993-09-01

    This program is focused on the corrosion, stress corrosion and corrosion fatigue behavior of Type 316 stainless steel (316SS) at 50, 90, and 130 C in high-purity water. Irradiated solution tests are performed using high-energy photon radiation. Purpose of this work is to determine the effects of radiolysis products on the environmental stability of 316SS in support of the ITER first wall/shield/blanket design. Preliminary results suggest that irradiation of pure water at 50 C results in a shift in the electrochemical potential for 316SS of approximately 100mV in the active direction and nearly an order of magnitude increase in the passive current density as compared to non-irradiated conditions. This proposal outlines a three-year program to develop corrosion design criteria for the use of 316SS in an ITER environment.

  13. Aromatic quinoxaline as corrosion inhibitor for bronze in aqueous chloride solution

    Indian Academy of Sciences (India)

    N Saoudi; A Bellaouchou; A Guenbour; A Ben Bachir; E M Essassi; M El Achouri

    2010-06-01

    A new corrosion inhibitor, viz. 3-ethyl-6-méthyl-quinoxalin-2-one, 1-benzyl-6-methyl-quinoxalin- 2-one, 2-benzyloxy-3,6-dimethyl-quinoxaline, 1-benzyl-3-methyl-quinoxalin-2-one, were synthesized in the laboratory. Their influence on the inhibition on corrosion of bronze in aqueous chloride solution (3% NaCl) was studied by electrochemical polarization methods and weight-loss measurements. The impact of temperature on the effectiveness of the substances mentioned above has been determined between 20 and 60°C. The results showed that the corrosion resistance was greatly enhanced in the presence of inhibitor and that the effectiveness depends on some physicochemical properties of the molecule, related to its functional groups. These compounds act through the formation of a protective film on the surface of the alloy.

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

    International Nuclear Information System (INIS)

    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

  15. Influence of aqueous environment pH on the corrosion behaviour of the CANDU steam generator tubing material

    International Nuclear Information System (INIS)

    The generalized corrosion is an undesirable process because it is accompanied by deposition of the corrosion products which affect the steam generator performances. It is very important to understand the generalized corrosion mechanism in order to evaluate the amounts of corrosion products which exist in the steam generator after a determined period of operation. The purpose of the experimental research consists in the assessment of corrosion behavior of the tube material (Incoloy-800) 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 cycloheyilamine (all volatile treatment). The results are presented as micrographs and graphics representing loss of metal by corrosion, corrosion rate, the total corrosion products, the adherent corrosion product, the released corrosion products and the release of the metal. (authors)

  16. Al-MoSi2 Composite Materials: Analysis of Microstructure, Sliding Wear, Solid Particle Erosion, and Aqueous Corrosion

    Science.gov (United States)

    Gousia, V.; Tsioukis, A.; Lekatou, A.; Karantzalis, A. E.

    2016-02-01

    In this effort, AMCs reinforced with new intermetallic phases, were produced through casting and compared as far as their microstructure, sliding wear, solid particle erosion, and aqueous corrosion response. Casting was selected as a production method based on the concept: (a) ease-to-handle and low cost production route and (b) optimum homogeneity of the reinforcing phase distribution. The MoSi2 phase was produced through vacuum arc melting and the resulting drops were milled for 30 h to produce fine powder, the characteristics of which were ascertained through SEM-EDS and XRD analysis. MoSi2 was used as precursor source for the final reinforcing phase. The powder material was incorporated in molten Al1050 alloy to additions of 2, 5 and 10 vol.% respectively. Extensive reactivity between the molten Al and the MoSi2 particles was observed, leading to the formation of new reinforcing phases mainly of the Al-Mo system. In all cases, a uniform particle distribution was observed, mainly characterized by isolated intermetallic phases and few intermetallic phase clusters. Sliding wear showed a beneficial action of the reinforcing phase on the wear of the composites. Surface oxidation, plastic deformation, crack formation, and debris abrasive action were the main degradation features. The results of solid particle erosion showed that the mechanism is different as the impact angle and the vol.% change. Regarding the corrosion, the analysis revealed localized corrosion effects. The composite behavior was not altered significantly compared to that of the monolithic matrix.

  17. Evaluation of alternative descriptions of PWR cladding corrosion behavior

    International Nuclear Information System (INIS)

    A statistical procedure has been used to evaluate several alternative descriptions of pressurized water reactor (PWR) cladding corrosion behavior, using an extensive database of Improved (low tin) Zr-4 cladding corrosion measurements from fuel irradiated in commercial PWRs. The in-reactor corrosion enhancement factors considered in the model development are based on a comprehensive review of the current literature for PWR cladding corrosion phenomenology and models. In addition, because prediction of PWR cladding corrosion behavior is very sensitive to the values used for the oxide surface temperatures, several models for the forced convection and sub-cooled nucleate boiling (SNB) coolant heat transfer under PWR conditions have also been evaluated. This evaluation determined that the choice of the forced convection heat transfer has the greatest impact on the ability to fit the data. In addition, the SNB heat transfer model used must account for a continuous transition from forced convection conditions to fully developed SNB conditions. With these choices for the heat transfer models, the evaluation determined that the significant in-reactor corrosion enhancement factors are related to the formation of a hydride rim at the cladding outer diameter, the coolant lithium concentration, and the fast neutron fluence (author) (ml)

  18. Transport and Corrosion Behavior of Cracked Reinforced Concrete

    DEFF Research Database (Denmark)

    Pease, Bradley Justin

    developed which estimates the ingress of aggressive substances by relating crack parameters and environmental conditions to transport mechanisms. Furthermore, the subsequent corrosion behavior of reinforcing steel will be characterized to determine how cracking influences the corrosion initiation and...... addition, cracks develop in concrete through various physical and chemical processes, which occur at varying periods of the lifetime of a structure, resulting in varying crack parameters (i.e. width, depth, and tortuosity). These cracks provide easy access of aggressive substances from the environment to...... enter the concrete. This is, among others, important in the corrosion of reinforcing steel. When cracks protrude to the depth of reinforcing steel, liquids containing aggressive ions (i.e. chlorides associated with salts and sea water) may rapidly access and initiate corrosion of the reinforcing...

  19. Oxidation and Hot Corrosion Behavior of a Composite Coating System

    Institute of Scientific and Technical Information of China (English)

    Dongbai XIE; Fuhui WANG

    2003-01-01

    The oxidation and hot corrosion behavior of Co-Ni-Cr-Al-Ta-Y coating produced by magnetron sputtering with and without enamel coating has been investigated in air at 900℃ and in molten 75 wt pct NaCl+25 wt pct Na2SO4at 850℃. The results show that the enamel coating possesses good hot corrosion resistance in the molten salts, in comparison with the sputtered Co-Ni-Cr-Al-Ta-Y coating. In the hot corrosion test, breakaway corrosion did not occur on the samples with enamel coating and the composition of enamel coating did not significantly change either. The oxidation resistance of the sputtered coating, which offers good adhesion, can be improved by the enamel coating.

  20. Corrosion behavior of W implanted aluminum

    International Nuclear Information System (INIS)

    Ion implantation is a technique that allows the insertion of various elements in the superficial part of materials, forming surface alloys. Moreover there is the possibility of forming solutions beyond the limits of solubility imposed by the thermodynamic relationships, which is of particular interest when the low solubility of the alloys avoids them to reach the desired level of a certain element in order to improve a certain property. The present investigation looks at the influence of tungsten implanted in aluminum, from the point of view of improved corrosion resistance. Comparative electrochemical results in neutral and alkaline solutions in the presence of chlorides are presented. The results show that for pH's where AlOOH is insoluble the WO3 stabilizes the oxide film, making the alloy less prone to pitting corrosion

  1. Corrosion behavior of superhydrophobic surfaces: A review

    OpenAIRE

    Mohamed, Adel M.A.; Abdullah, Aboubakr M.; Younan, Nathalie A.

    2015-01-01

    Superhydrophobic surfaces have evoked great interest in researchers for both purely academic pursuits and industrial applications. Metal corrosion is a serious problem, both economically and operationally, for engineering systems such as aircraft, automobiles, pipelines, and naval vessels. Due to the broad range of potential applications of superhydrophobic surfaces, there is a need for a deeper understanding of not only how to fabricate such surfaces using simple methods, but also how specif...

  2. Corrosion behavior on aluminum alloy LY12 in simulated atmospheric corrosion process

    Institute of Scientific and Technical Information of China (English)

    WANG Zhen-yao; MA Teng; HAN Wei; YU Guo-cai

    2007-01-01

    The corrosion behavior of typical high-strength aluminum alloy LY12 was studied by accelerated corrosion tests of cyclic wet-dry-immersion containing media of NaHSO3 and NaCl to simulate the corrosion process in different atmosphere environment, and the corrosion mechanism was also discussed. The main experimental techniques include mass loss, morphological check, analysis of corrosion products and electrochemical measurement. The result shows that the mass loss of LY12, with or without cladding, has linear relationship with test time in the three kinds of chemical media, 0.02 mol/L NaHSO3, 0.006 mol/L NaCl and 0.02 mol/L NaHSO3+0.006 mol/L NaCl, respectively. A layer of cladding on high-strength aluminum alloy can raise evidently the resistance of atmospheric corrosion. Cl- can promote pitting generation on the oxide film of LY12 when HOS3- exists, LY12 can react much intensely with HOS3- derived from anions.

  3. Aqueous chloride stress corrosion cracking of titanium: A comparison with environmental hydrogen embrittlement

    Science.gov (United States)

    Nelson, H. G.

    1973-01-01

    The physical characteristics of stress corrosion cracking of titanium in an aqueous chloride environment are compared with those of embrittlement of titanium by a gaseous hydrogen environment in an effort to help contribute to the understanding of the possible role of hydrogen in the complex stress corrosion cracking process. Based on previous studies, the two forms of embrittlement are shown to be similar at low hydrogen pressures (100 N/sqm) but dissimilar at higher hydrogen pressures. In an effort to quantify this comparison, tests were conducted in an aqueous chloride solution using the same material and test techniques as had previously been employed in a gaseous hydrogen environment. The results of these tests strongly support models based on hydrogen as the embrittling species in an aqueous chloride environment. Further, it is shown that if hydrogen is the causal species, the effective hydrogen fugacity at the surface of titanium exposed to an aqueous chloride environment is equivalent to a molecular hydrogen pressure of approximately 10 N/sqm.

  4. Electrochemical corrosion behavior of stainless steel irradiated in FBR

    International Nuclear Information System (INIS)

    A cooperative research on the evaluation of fracture behaviors of neutron irradiated materials has been initiated in 1991 by the Japan Atomic Energy Research Institute (JAERI) and the Power Reactor and Nuclear Fuel Development Corporation (PNC). The research program includes a study of stress corrosion cracking (SCC) of the wrapper tube material of fuel assembly irradiated in the experimental fast reactor 'JOYO'. The program is related with a research activity on the irradiation assisted stress corrosion cracking (IASCC) at JAERI. To investigate the SCC behavior and to pursue its mechanism, knowledges about a corrosion behavior of the material are required. Therefore corrosion tests were performed on the irradiated material by employing electrochemical technique. On the wrapper tube material of type 316 stainless steel irradiated in 'JOYO' up to a neutron fluence of 7 x 1022 n/cm2 (E > 0.2 MeV) at about 400degC, the electrochemical potentiokinetic reactivation (EPR) test and the potentiostatic electrolytic test were carried out in the hot laboratory of JAERI. By EPR test a degradation of corrosion resistance due to the irradiation was detected. By the other test a possibility of grain boundary segregation of impurity elements was shown. (author)

  5. Galvanic Corrosion between Alloy 690 and Magnetite in Alkaline Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    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.

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

    International Nuclear Information System (INIS)

    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

  7. Corrosion behavior of alloy M5TM: experience feedback

    International Nuclear Information System (INIS)

    M5TMis the reference alloy developed by AREVA NP to meet all the demands of today's nuclear market. The excellent corrosion behavior is now clearly demonstrated in a wide range of environment and plant operations ands deeply analyzed up to 7 cycles and a burn up of nearly 80 GWd/tHM. Thus, M5TMis also a good candidate for structure components (guide tube and grid). The corrosion behavior of claddings or guide tube and grids are compared and appears as equivalent. To date he primary water chemistry evolutions (high Li or Zn addition) have no influence on the corrosion of M5TM. Then M5TMpresents all the guarantees to answer to high duty and high burn up demands

  8. N-[Isononylphenoxypoly(ethyleneoxy)carbonylmethyl]ammonium chlorides as inhibitors of metal corrosion. 1. Inhibition of steel corrosion in aqueous hydrochloric media

    International Nuclear Information System (INIS)

    New ammonium compounds of the type N-[isononylphenoxypoly (ethyleneoxy) carbonylmethyl] ammonium chlorides were synthesized. The compounds were studied as inhibitors of steel corrosion in hydrochloric aqueous media. High efficiency of the corrosion inhibitors suggested is shown. Dependence of their inhibiting properties on the type of substituents at nitrogen atom, length of hydrocarbon radicals and number of ethyleneoxide groups in isononylphenoxypoly (ethyleneoxy) carbonylmethyl radical was revealed

  9. Corrosion characteristics of seven metals in three aqueous environments for forensic applications

    Science.gov (United States)

    Tong, Tianqi

    Corrosion characteristics of seven varieties of metals---zinc, brass C260, stainless steel 302, stainless steel 316, stainless steel 420, stainless steel 430, and stainless steel 440---in three aqueous media---Atlantic Ocean, Charles River, and deionized waters---were assessed via mass loss methods over 32 weeks, with supplemental data in the form of photomicrographic records. Concurrently, tests were conducted to determine the degree of measurement error resulting from the analytical scale used during corrosion assessment. This was accomplished by using reference samples of each type of metal and a glass vial as the container that held the metal and water samples. These error tests indicated that while the mass error associated with the metal samples was low, the error in mass associated with the vial displayed error margins two orders of magnitude larger than the error margins for the smaller metal samples. Further, control tests and statistical analysis indicated that this variation was the result of some quality inherent to the vial. The metal samples involved in the corrosion assessment experiment generally displayed corrosion characteristics in agreement with trends reported in the literature. Zinc produced the greatest quantity of corrosion residues out of all the metals studied. Brass C260 also developed visible corrosion. For example, brass C260 developed dark green/brown adherent residue and whitish blue-tinted nonadherent residue in Atlantic Ocean water, faint greenish tarnishing and some dark green spots and dots over time in Charles River water, and only faint greenish tarnish in deionized water. In contrast with zinc and brass C260, the stainless steels did not exhibit signs of significant corrosion rates excepting stainless steel 420 (SS420), which displayed pitted features surrounded by multi-colored rings on all of its Atlantic Ocean immersion samples and 25% of its Charles River immersion samples. Atlantic Ocean water generally caused the greatest

  10. Mechanical Properties and Corrosion Behavior of Low Carbon Steel Weldments

    Directory of Open Access Journals (Sweden)

    Mohamed Mahdy

    2013-01-01

    Full Text Available This research involves studying the mechanical properties and corrosion behavior of “low carbon steel” (0.077wt% C before and after welding using Arc, MIG and TIG welding. The mechanical properties include testing of microhardness, tensile strength, the results indicate that microhardness of TIG, MIG welding is more than arc welding, while tensile strength in arc welding more than TIG and MIG.The corrosion behavior of low carbon weldments was performed by potentiostat at scan rate 3mV.sec-1 in 3.5% NaCl to show the polarization resistance and calculate the corrosion rate from data of linear polarization by “Tafel extrapolation method”. The results indicate that the TIG welding increase the corrosion current density and anodic Tafel slop, while decrease the polarization resistance compared with unwelded low carbon steel. Cyclic polarization were measured to show resistance of specimens to pitting corrosion and to calculate the forward and reveres potentials. The results show shifting the forward, reverse and pitting potentials toward active direction for weldments samples compared with unwelded sample.

  11. Influence of Aluminum Ions Implantation on Corrosion Behavior of Zircaloy-2 Alloy in 1 M H2SO4

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The specimens were implanted with aluminum ions with fluence ranging from 1×1016 to 1×1017 ions/cm2 to study the effect of aluminum ion implantation on the aqueous corrosion behavior of zircaloy-2 by metal vapor vacuum arc source (MEWA) at an extraction voltage of 40 kV. The valence states and depth distributions of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), respectively. Transmission electron microscopy (TEM) was used to examine the microstructure of the aluminum-implanted samples. Glancing angle X-ray diffraction (GAXRD)was employed to examine the phase transformation due to the aluminum ion implantation. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zircaloy-2 in a 1 M H2SO4 solution. It is found that a significant improvement was achieved in the aqueous corrosion resistance of zircaloy-2 implanted with aluminum ions. Finally, the mechanism of the corrosion behavior of aluminum-implanted zircaloy-2 was discussed.

  12. The corrosion behavior of in-situ Zr-based metallic glass matrix composites in different corrosive media

    Science.gov (United States)

    Tian, H. F.; Qiao, J. W.; Yang, H. J.; Wang, Y. S.; Liaw, P. K.; Lan, A. D.

    2016-02-01

    The corrosion behavior of Zr58.5Ti14.3Nb5.2Cu6.1Ni4.9Be11.0 metallic glass matrix composites (MGMCs) in different corrosive media, including 1 M NaCl, 1 M HCl, 0.5 M H2SO4, and 1 M NaOH solutions, was studied. The electrochemical characteristics of the composites were investigated by potentiodynamic-polarization measurements. The results show that the corrosion resistance in NaOH solution is the poorest in terms of the corrosion potential (Ecorr) and corrosion current density (icorr). For comparison, the chemical immersion tests were conducted. The corroded surface morphologies after electrochemical and immersion measurements both show that the amorphous matrix and crystalline dendrites exhibit different corrosion behaviors. The possible interpretation of the observed morphology evolution was proposed. The effect of a very base metallic element of beryllium on the corrosion dynamic process has been emphasized.

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

    International Nuclear Information System (INIS)

    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)

  14. 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.

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

    International Nuclear Information System (INIS)

    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 oC. 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.

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

    International Nuclear Information System (INIS)

    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)

  17. Effects of bicarbonate and sulfate ions on the pitting corrosion behavior of copper

    International Nuclear Information System (INIS)

    The strategy for disposal of high-level radioactive waste in China is to enclose the spent nuclear fuel in sealed metal canisters which are embedded in bentonite clay hundreds meters down in the bed-rock. The choice of container material depends largely on the redox conditions and the aqueous environment of the repository. One of the choices for the fabrication of waste canisters is copper, because it is thermodynamically stable under the saline, anoxic conditions over the large majority of the container lifetime. However, in the early aerobic phase of the geological disposal the corrosion of copper could take place, and the corrosion behavior of copper would be influenced by the complex chemical conditions of groundwater markedly. Pitting corrosion of copper often take place in power plants or air-conditioning condensate water. The corrosion environment usually contains bicarbonate, sulfate and chloride ions. In the early stage of geological disposal, if the aerobic water with bicarbonate, sulfate and chloride ions immersion repository, the pitting corrosion of copper may occur. The content of bicarbonate and sulfate ion in the water chemistry environment, as well as the synergy between them, could affect the behavior of pitting seriously. The content of bicarbonate and chloride ion in the water chemistry environment, as well as the synergy between them, could affect the behavior of pitting seriously. The researchers generally agreed that chloride ions would promote the occurrence of pitting corrosion of copper, and bicarbonate ions will lead to surface passivation and inhibition of pitting. However, there is no systematic work in this area. In our work, the cycle polarization behavior and surface morphology of pitting has been investigated in HCO3- and Cl- mixed solution, respectively by electrochemical cyclic polarization test and scanning electron microscopy. The results show that the circular polarization curves of copper could be divided into four types. The

  18. CO2 Corrosion and Grooving Corrosion Behavior of the ERW Joint of the Q125 Grade Tube Steel

    Institute of Scientific and Technical Information of China (English)

    Li-dong WANG; Feng-lei LIU; Qing-yun ZHAO; Hui-bin WU

    2015-01-01

    In order to investigate the CO2 corrosion behavior and the grooving corrosion susceptibility of electric resistance welded tubes of the Q125 grade, the high temperature and high pressure autoclave was employed to conduct CO2 corrosion experiments for the welded joint. The mechanisms of grooving corrosion and the factors inlfuencing grooving corrosion susceptibility were identiifed by electrochemical measurement, microstructure observation, residual stress examination, micro-region composition and orientation analysis. The CO2 corrosion results show that the corrosion resistance of the base material is the best, followed by heat-affected zone and the welded seam is the worst. The grooving corrosion occurred in the welded seam, and the grooving corrosion susceptibility of welded seam is relativity high. The dominated reason for the grooving corrosion of the electric resistance welded jointis the notable inclusions consisting of MnS as the main content in the welded seam.The proportion of high-angle grain bound-aries in the welding zone is higher than that of base metal and the heat affected zone, which plays an important role in the corrosion behavior of the welded seam.

  19. Failure behavior of protective organic coatings under corrosive conditions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xian-cheng; XU Bin-shi; WANG Hai-dou; WU Yi-xiong

    2004-01-01

    Recent research activities on the formation of micro-defects and porosity in organic coatings were reviewed. The mechanisms of aggressive ionic conduction through organic coatings were analyzed. The micro-mechanisms for the failure behavior of coatings under corrosive environments were discussed in detail. These mechanisms included blistering (i. e. osmotic blistering, anodic blistering and cathodic blistering) in the coating, wet-adhesion loss at the substrate/coating interface, cathodic delamination of coating from the substrate. Based on these researches, it was found that the failure behavior of organic coatings is closely related to the micro-defects in coatings, regardless of the failure mode. Additionally, the general failure mode of a coating system was proposed to interpret the failure behavior of organic in corrosion environments. The topics discussed can provide some insights into the development of a methodology for designing fail-safe coating systems.

  20. Corrosion behavior of leaded-bronze alloys in sea water

    Energy Technology Data Exchange (ETDEWEB)

    Zohdy, K.M., E-mail: khalzohdy@yahoo.com [Higher Technological Institute, 10" t" h of Ramadan City (Egypt); Sadawy, M.M. [Mining and Petroleum Engineering Department, Al-Azhar University, Nasr City, Cairo 11371 (Egypt); Ghanem, M. [Industrial Education, Suez University (Egypt)

    2014-10-15

    The corrosion behavior of leaded-bronze alloys (Cu–5Sn–5Zn–5Pb, Cu–8Sn–8Zn–8Pb and Cu–10Sn–10Zn–10Pb) in sea water was investigated using weight loss method, open-circuit potential measurements (OCP), polarization techniques and electrochemical impedance spectroscopy (EIS). The nature and morphology of the corrosion products were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the corrosion resistance decreases with decreasing copper content. The XRD indicated that the composition of patina depends on the concentration of Cu, Sn, Zn and Pb in each alloy. - Highlights: • The corrosion potential of leaded bronze shifts to more noble potential. • The corrosion resistance increases with increasing amount of copper content in leaded bronze alloys. • The patina formed on Cu–5Sn–5Zn–5Pb is more uniform and protective than other alloys. • The composition of patina formed on leaded bronze depends on the concentration of Cu, Sn, Zn and Pb in the alloy.

  1. Corrosion behavior of β titanium alloys for biomedical applications

    International Nuclear Information System (INIS)

    The corrosion behavior of biocompatible β titanium alloys Ti-13Mo-7Zr-3Fe (TMZF) and Ti-35Nb-7Zr-5Ta (TiOsteum) was investigated in 0.9% NaCl and 5 M HCl solutions. Extra-low-interstitial Ti-6Al-4V, which is also a candidate material for biomedical applications, was studied for comparison. The as-received TiOsteum and TMZF alloys exhibited single-phase β and α + β microstructures, respectively, so the latter was also investigated in the solutionized and quenched condition. In 0.9% NaCl solution, all three alloys exhibited spontaneous passivity and very low corrosion rates. Ti-6Al-4V and the as-received TMZF exhibited active-passive transitions in 5 M HCl whereas TiOsteum and TMZF in the metastable β condition showed spontaneous passivity. Potentiodynamic polarization tests, weight loss and immersion tests revealed that TiOsteum exhibited the best corrosion resistance in 5 M HCl. Analysis of surfaces of the corroded specimens indicated that the α/β phase boundaries were preferential sites for corrosion in Ti-6Al-4V while the β phase was preferentially attacked in the two-phase TMZF. The performance of the alloys in corrosive environment was discussed in terms of the volume fraction of the constituent phases and partitioning of alloying elements between these phases.

  2. Corrosion behavior of leaded-bronze alloys in sea water

    International Nuclear Information System (INIS)

    The corrosion behavior of leaded-bronze alloys (Cu–5Sn–5Zn–5Pb, Cu–8Sn–8Zn–8Pb and Cu–10Sn–10Zn–10Pb) in sea water was investigated using weight loss method, open-circuit potential measurements (OCP), polarization techniques and electrochemical impedance spectroscopy (EIS). The nature and morphology of the corrosion products were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the corrosion resistance decreases with decreasing copper content. The XRD indicated that the composition of patina depends on the concentration of Cu, Sn, Zn and Pb in each alloy. - Highlights: • The corrosion potential of leaded bronze shifts to more noble potential. • The corrosion resistance increases with increasing amount of copper content in leaded bronze alloys. • The patina formed on Cu–5Sn–5Zn–5Pb is more uniform and protective than other alloys. • The composition of patina formed on leaded bronze depends on the concentration of Cu, Sn, Zn and Pb in the alloy

  3. Corrosion behavior of {beta} titanium alloys for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Atapour, M. [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210 (United States); Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Pilchak, A.L. [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210 (United States); Air Force Research Laboratory, Materials and Manufacturing Directorate/RXLM, Wright Patterson Air Force Base, OH 45433 (United States); Universal Technology Corporation, Dayton OH 45432 (United States); Frankel, G.S., E-mail: frankel.10@osu.edu [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210 (United States); Williams, J.C. [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210 (United States)

    2011-07-20

    The corrosion behavior of biocompatible {beta} titanium alloys Ti-13Mo-7Zr-3Fe (TMZF) and Ti-35Nb-7Zr-5Ta (TiOsteum) was investigated in 0.9% NaCl and 5 M HCl solutions. Extra-low-interstitial Ti-6Al-4V, which is also a candidate material for biomedical applications, was studied for comparison. The as-received TiOsteum and TMZF alloys exhibited single-phase {beta} and {alpha} + {beta} microstructures, respectively, so the latter was also investigated in the solutionized and quenched condition. In 0.9% NaCl solution, all three alloys exhibited spontaneous passivity and very low corrosion rates. Ti-6Al-4V and the as-received TMZF exhibited active-passive transitions in 5 M HCl whereas TiOsteum and TMZF in the metastable {beta} condition showed spontaneous passivity. Potentiodynamic polarization tests, weight loss and immersion tests revealed that TiOsteum exhibited the best corrosion resistance in 5 M HCl. Analysis of surfaces of the corroded specimens indicated that the {alpha}/{beta} phase boundaries were preferential sites for corrosion in Ti-6Al-4V while the {beta} phase was preferentially attacked in the two-phase TMZF. The performance of the alloys in corrosive environment was discussed in terms of the volume fraction of the constituent phases and partitioning of alloying elements between these phases.

  4. Corrosion Behaviors of Steel A3 Exposed to Thiobacillus Ferrooxidans

    Institute of Scientific and Technical Information of China (English)

    Jianhua LIU; Xin LIANG; Songmei LI

    2008-01-01

    The corrosion behaviors of steel A3 in synergistic action of Thiobacillus ferrooxidans (T.f) and electrochemically accelerated corrosion were studied by electrochemical, microbiology and surface analysis methods. The open circuit potential (Eocp) and electrochemical impedance spectroscopy (EIS) of the steel A3 electrodes were measured in leathen culture medium without and with T.f (simply called T.f solution in the following paper)in immersion electrode way at the time of the 2nd, 5th, 10th, 20th and 30th days, respectively. It was found that Eocp of the electrode for immersion in leathen culture medium shifted negatively with the immersion time while that for immersion in T.f solutions shifted negatively, then positively and finally negatively. On the 20th day, the corrosion of steel A3 for immersion in culture medium was in pitting initiation stage while that for immersion in T.f solutions was in pitting growth stage. It was found that the corrosion of steel A3 was accelerated by T.f. The morphology of corrosion product of steel A3 immersion in T.f solutions observed through scanning electron microscopy (SEM) transformed from solid globules to tabular plates and to spongy globules and plates.

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

    International Nuclear Information System (INIS)

    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 600C 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)

  6. Stress Corrosion Cracking of ferrito-pearlitic steel in aqueous environment containing dissolved CO2

    OpenAIRE

    Vancostenoble, Alix; Duret-Thual, C.; Bosch, Cédric; Delafosse, David

    2014-01-01

    A confined aqueous environment is defined by a very low water-volume to exposed steel-area ratio. In such media containing dissolved CO2, siderite is formed and acts as a protective film. An addition of applied stress and/or environmental fluctuation can disturb the balance between the steel and this protective film, causing the fracture of the latter and leading to Stress Corrosion Cracking (SCC). The material studied is a cold drawn and rolled high strength steel composed of ferrite and sph...

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

    OpenAIRE

    Zhongyu Cui; Xiaogang Li; Huan Zhang; Kui Xiao; Chaofang Dong; Zhiyong Liu; Liwei Wang

    2015-01-01

    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 ...

  8. Corrosion behavior of zirconia in acidulated phosphate fluoride

    OpenAIRE

    Anie Thomas; Sathyanarayanan Sridhar; Shant Aghyarian; Pilanda Watkins-curry; Chan, Julia Y.; Alessandro Pozzi; Danieli C. Rodrigues

    2016-01-01

    ABSTRACT Objective The corrosion behavior of zirconia in acidulated phosphate fluoride (APF) representing acidic environments and fluoride treatments was studied. Material and Methods Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM). Sample mass and dimensions were measured for mass loss determination. Samples were charac...

  9. Corrosion behavior of zirconia in acidulated phosphate fluoride

    OpenAIRE

    Thomas, Anie; Sridhar, Sathyanarayanan; Aghyarian, Shant; Watkins-Curry, Pilanda; Chan, Julia Y.; Pozzi, Alessandro; Danieli C. Rodrigues

    2016-01-01

    ABSTRACT Objective The corrosion behavior of zirconia in acidulated phosphate fluoride (APF) representing acidic environments and fluoride treatments was studied. Material and Methods Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM). Sample mass and dimensions were measured for mass loss determination. Samples were characteri...

  10. SCC Behavior of Alloy 690 in Leaded Aqueous Solution

    International Nuclear Information System (INIS)

    Alloy 690 (Ni 60wt%, Cr 30wt%, Fe 10wt%) is used and planned to use as a heat exchanger tube of the steam generator (SG) and an alternative of Alloy 600 (Ni 75wt%, Cr 15wt%, Fe 10wt%) due to a relatively high stress corrosion cracking (SCC) susceptibility of Alloy 600 under operating condition of nuclear power plant (NPP). Secondary water pH which affects SCC behavior substantially is widely spanned from acid to alkaline in crevice depending on water chemistry control, water chemistry in crevice, plant specific condition, etc. Especially, specific chemical species are accumulated in the crevice of the sludge leading to a specific condition of crevice chemistry. Among these chemical species, lead is known to be one of the most deleterious species in the reactor coolants that cause SCC of the alloy. Even Alloy 690 is not strong in alkaline solution with lead. Lead has been effectively detected in all tubesheet samples, crevice deposits and surface scales removed from SGs. Typical concentrations are 100 to 500 ppm but in some plants, concentrations as high as 2,000 to 10,000ppm has been detected. The best method to prevent lead induced SCC (PbSCC) is to eliminate the harmful lead from the NPP chemistry, which is not possible and most NPPs are already contaminated by lead. Moreover only a very low level of sub ppm affects PbSCC. Therefore the mechanistic understanding of PbSCC is very crucial to control and mitigate PbSCC. It is expected that an addition of lead into a solution modifies the oxide property considering that a passivity of oxide is directly related to SCC behavior. A finding of the way to avoid this modification can give us a key to control PbSCC such as an inhibitor. In the present work, an SCC susceptibility was investigated in the presence of lead and NiB as an inhibitor as well as in the absence of both impurities by using a slow strain rate tensile (SSRT) test. Moreover the oxides formed on Alloy 690 in aqueous solutions with and without lead were

  11. 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)

    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

  12. Corrosion Behavior of Alloys in Molten Fluoride Salts

    Science.gov (United States)

    Zheng, Guiqiu

    The molten fluoride salt-cooled high-temperature nuclear reactor (FHR) has been proposed as a candidate Generation IV nuclear reactor. This reactor combines the latest nuclear technology with the use of molten fluoride salt as coolant to significantly enhance safety and efficiency. However, an important challenge in FHR development is the corrosion of structural materials in high-temperature molten fluoride salt. The structural alloys' degradation, particularly in terms of chromium depletion, and the molten salt chemistry are key factors that impact the lifetime of nuclear reactors and the development of future FHR designs. In support of materials development for the FHR, the nickel base alloy of Hastelloy N and iron-chromium base alloy 316 stainless steel are being actively considered as critical structural alloys. Enriched 27LiF-BeF2 (named as FLiBe) is a promising coolant for the FHR because of its neutronic properties and heat transfer characteristics while operating at atmospheric pressure. In this study, the corrosion behavior of Ni-5Cr and Ni-20Cr binary model alloys, and Hastelloy N and 316 stainless steel in molten FLiBe with and without graphite were investigated through various microstructural analyses. Based on the understanding of the corrosion behavior and data of above four alloys in molten FLiBe, a long-term corrosion prediction model has been developed that is applicable specifically for these four materials in FLiBe at 700ºC. The model uses Cr concentration profile C(x, t) as a function of corrosion distance in the materials and duration fundamentally derived from the Fick's diffusion laws. This model was validated with reasonable accuracy for the four alloys by fitting the calculated profiles with experimental data and can be applied to evaluate corrosion attack depth over the long-term. The critical constant of the overall diffusion coefficient (Deff) in this model can be quickly calculated from the experimental measurement of alloys' weight

  13. CORROSION AND MECHANICAL BEHAVIOR OF COPPER- NIOBIUM NANO-FILAMENTARY MICRO-COMPOSITES FOR HIGH PERFORMANCE ELECTRICAL CONDUCTOR WIRE

    Institute of Scientific and Technical Information of China (English)

    Y. Choi; T.W. Lim; S.I. Hong

    2002-01-01

    Corrosion behavior of heavily drawn bundled Copper-niobium filamentary micro-composite was studied as a function of niobium content to develop the relationshipbetween microstructure and corrosion behavior in aqueous 30% HCl-FeCl3 solution.TEM observation revealed that niobium filaments were distributed regularly in coppermatrix along the sides of a triangular unit cell in the transverse section and more sub-grain boundaries were absorbed at copper/niobium phase boundaries with increasingniobium content. The corrosion potential and rate in aqueous 30% HCl-10% FeCl3 was-680.3mVSHE and 1.179×10-5A/cra2. The corrosion potential and rate decreasedas increasingniobium content and FeCl3. The yield stress can be described as thesum of the substructure strengthening component due to elongated grains, subgrainsand/or cells, the phase boundary strengthening term associated with the Hall-Petchtype interaction between dislocations and phase boundaries and precipitate strength-ening component.

  14. 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.

  15. The structure and corrosion behavior of electron beam treated austenitic stainless steels

    International Nuclear Information System (INIS)

    The influence of electron beam surface melting of austenitic AISI 304 stainless steel on its microstructure and anodic potentiostatic behavior in 1N sulphuric acid at 25 C has been studied. Delta ferrite formed in the surface melted layer and was found to vary with electron beam current and stainless steel plate thickness. The structure and anodic behavior of AISI 304 specimens conventionally heat treated to provoke ferrite formation were also studied. The length of active region in the anodic potentiostatic curves for both the surface melted and heat treated specimens decreased with increasing ferrite in the austenitic steel. Overall, surface melting using high energy sources has been found to significantly improve the aqueous corrosion resistance of austenitic stainless steel by provoking the formation of duplex microstructures. (author)

  16. 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.

  17. Corrosion behavior of magnetic ferrite coating prepared by plasma spraying

    International Nuclear Information System (INIS)

    Graphical abstract: The saturation magnetization (Ms) of the ferrite coating is 34.417 emu/g while the Ms value of the ferrite powder is 71.916 emu/g. It can be seen that plasma spray process causes deterioration of the room temperature soft magnetic properties. - Highlights: • Spinel ferrite coatings have been prepared by plasma spraying. • The coating consists of nanocrystalline grains. • The saturation magnetization of the ferrite coating is 34.417 emu/g. • Corrosion behavior of the ferrite coating was examined in NaCl solution. - Abstract: In this study, spray dried spinel ferrite powders were deposited on the surface of mild steel substrate through plasma spraying. The structure and morphological studies on the ferrite coatings were carried out using X-ray diffraction, scanning electron microscope and Raman spectroscopy. It was showed that spray dried process was an effective method to prepare thermal spraying powders. The coating showed spinel structure with a second phase of LaFeO3. The magnetic property of the ferrite samples were measured by vibrating sample magnetometer. The saturation magnetization (Ms) of the ferrite coating was 34.417 emu/g. The corrosion behavior of coating samples was examined by electrochemical impedance spectroscopy. EIS diagrams showed three corrosion processes as the coating immersed in 3.5 wt.% NaCl solution. The results suggested that plasma spraying was a promising technology for the production of magnetic ferrite coatings

  18. 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.

  19. Corrosion and electrochemical behaviors of pure aluminum in novel KOH-ionic liquid-water solutions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.M.; Wang, J.B.; Shao, H.B.; Zeng, X.X. [Department of Chemistry, Zhejiang University, Hangzhou 310027, (China); Zhang, J.Q.; Cao, C.N. [Department of Chemistry, Zhejiang University, Hangzhou 310027, (China); State Key Laboratory for Corrosion and Protection of Metal, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016, (China)

    2009-12-15

    The corrosion and electrochemical behaviors of pure aluminum in KOH-ionic liquid-water solutions with variable volume ratios of water and the ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate (BMIMBF{sub 4}) were for the first time investigated by means of hydrogen collection, polarization curve, galvanostatic discharge, and electrochemical impedance spectroscopy (EIS). The results of hydrogen collection experiments showed that aluminum has a low corrosion rate in KOH-BMIMBF{sub 4}-H{sub 2}O solutions, and the corrosion rate decreases with increase in BMIMBF{sub 4} content in the electrolytes. The results of electrochemical experiments revealed that aluminum is electrochemically active over a very wide potential window in the KOH-BMIMBF{sub 4}-H{sub 2}O solutions, and its electrochemically kinetic mechanism is similar to that in the corresponding aqueous solution; the increase in KOH and water contents in the electrolytes may improve the anodic dissolution performance of aluminum. It was found that aluminum presents excellent galvanostatic discharge performance in the 2.0 M KOH BMIMBF{sub 4}-H{sub 2}O mixed solution with 60% water. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  20. Corrosion

    Science.gov (United States)

    Slabaugh, W. H.

    1974-01-01

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

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

    International Nuclear Information System (INIS)

    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/cm2 and −13.5225 mg/cm2 respectively. The surface morphology of sample in presence of salt mixture showed scale spallation. Oxide scales of Fe3O4, Fe2O3 were the main phases developed and detected by XRD technique. Cr2O3 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

  2. Corrosion inhibitors for carbon steel in neutral aqueous media based on the products of sugar cane processing. 3. Combined inhibitors

    International Nuclear Information System (INIS)

    Combined (mixed) inhibitors of metal corrosion in aqueous media are developed on the fasis of mixtures of 5-nitro furancarboxylic acid salts (nitrofuroat) with inorganic passivators (nitrite, phosphate, tetraborate) or with nitrogen-containing derivatives of furfural (furfurine, furfurylamine). Their efficiency is confirmed by electrochemical and weighing investigations carried outn under lamoratory and industrial conditions

  3. Corrosion behavior of novel 3%Cr pipeline steel in CO2 Top-of-Line Corrosion environment

    International Nuclear Information System (INIS)

    Highlights: ► CO2 Top-of-Line Corrosion environment in wet gas pipelines was simulated. ► Compared with X70, the resistance to CO2 TLC of novel 3%Cr pipeline steel is better. ► The effect of Cr enrichment in the corrosion scale on CO2 TLC is confirmed. -- Abstract: CO2 Top-of-Line Corrosion (TLC) of carbon steel pipelines is a serious problem for wet gas transportation. We have studied the corrosion behavior of novel 3%Cr (3Cr) pipeline steel and conventional carbon steel (X70) in the simulated CO2 TLC environment. The composition and morphology of the corrosion scale are characterized by X-ray diffraction, energy dispersive X-ray spectroscopy and scanning electron microscopy analyses. The results indicate that 3Cr pipeline steel shows superior resistance to CO2 TLC, exhibiting uniform corrosion with duplex corrosion layer, while X70 suffers severe localized corrosion. It was suggested that the inner Cr enriched layer enhanced the protective ability of the scale to steel substrate and improved the resistance to localized corrosion in CO2 TLC environment.

  4. Effect of Ca2+ and Mg2+ on CO2 Corrosion Behavior of Tube Steel

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guo-xian; LI Jian-ping; HAO Shi-ming; L(U) Xiang-hong; LI He-lin

    2005-01-01

    Effects of Ca2+ and Mg2+ on the CO2 corrosion behaviors of tube steel were studied in simulated oil-fieldenvironment. The influence of Ca2+ and Mg2+ on the corrosion rate and morphologies of corrosion product layerwas determined by scanning electron microscope and measuring mass loss. Potentiodynamic polarization and im-pedance spectroscopy were used to investigate the change of electrochemical characteristic parameters of corrosionproduct layer and corrosion dynamic process. The results show that with Ca2+ and Mg2+ in electrolyte, the mor-phologies and microstructures of corrosion product layer changed obviously, thus affecting the corrosion process.

  5. Atmosphere corrosion behavior of plasma sprayed and laser remelted coatings on copper

    Institute of Scientific and Technical Information of China (English)

    Gongying Liang; T. T. Wong; Geng An; J. M. K. MacAlpine

    2006-01-01

    Nickel and chromium coatings were produced using plasma spraying and laser remelting on the copper sheet. The corrosion test was carried out in an acidic atmosphere, and the corrosive behaviors of both coatings and original copper samples were investigated by using an impedance comparison method. Experimental results show that nickel and chromium coatings display better corrosion resistance properties relative to the original pure copper sample. The corrosion rate of chromium coating is less than that of nickel coating, and corrosion resistances of laser remelted nickel and chromium samples are better thanthose of plasma sprayed samples. The corrosion deposit film of copper is loose compared with nickel and chromium.

  6. 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.

  7. Exfoliation Corrosion Behavior of 2B06 Aluminum Alloy in a Tropical Marine Atmosphere

    Science.gov (United States)

    Cui, Z. Y.; Li, X. G.; Xiao, K.; Dong, C. F.; Wang, L. W.; Zhang, D. W.; Liu, Z. Y.

    2015-01-01

    In this study, corrosion behavior of 2B06 aluminum alloy was investigated after exposure to a tropical marine atmosphere for up to 4 years. After 6 months, the specimen showed exfoliation corrosion as well as rapid increase in thickness loss and corrosion rate. Exfoliation corrosion was found to initiate from hydrogen-assisted intergranular cracks and propagate extensively due to the wedge effect of the corrosion products. During the exposure test, corrosion on the groundward surface was considerably more severe than that on the skyward surface, which could be attributed to the different exposure conditions on the two surfaces.

  8. Atmosphere corrosion behavior of plasma sprayed and laser remelted coatings on copper

    Science.gov (United States)

    Liang, Gongying; Wong, T. T.; An, Geng; MacAlpine, J. M. K.

    2006-01-01

    Nickel and chromium coatings were produced using plasma spraying and laser remelting on the copper sheet. The corrosion test was carried out in an acidic atmosphere, and the corrosive behaviors of both coatings and original copper samples were investigated by using an impedance comparison method. Experimental results show that nickel and chromium coatings display better corrosion resistance properties relative to the original pure copper sample. The corrosion rate of chromium coating is less than that of nickel coating, and corrosion resistances of laser remelted nickel and chromium samples are better than those of plasma sprayed samples. The corrosion deposit film of copper is loose compared with nickel and chromium.

  9. Corrosion Behavior of Au, Hastelloy C-276 Alloy and Monel 400 Alloy in Molten Lithium Fluoride

    Institute of Scientific and Technical Information of China (English)

    WANG; Chang-shui; GUO; Jun-kang

    2013-01-01

    For searching better corrosion-resistant material in high temperature,we investigated the corrosion behavior of Au,Haynes C-276 alloy and Monel 400 alloy in molten lithium fluoride at 950℃.The corrosion products and fine structures of the corroded specimens were characterized by inductively coupled plasma mass spectrometry(ICP-MS),scanning electron microscope(SEM),energy dispersive

  10. EFFECT OF LASER IRRADIATION ON CORROSION BEHAVIOR OF AS RECEIVED AND NI-DEPOSITED MARAGING STEEL

    OpenAIRE

    Shinde Sambhaji Dagadu

    2015-01-01

    The effect of pulsed LASER irradiation on the corrosion behavior of both the as -received and Ni-deposited maraging steel specimens has been studied using Q-switched Ruby Laser. In order to investigate the beneficial effects of alloying element on the corrosion behavior, Nickel deposition was carried out. Using the potentio-kinetic polarization technique, corrosion behavior of Ni-deposited and laser irradiated samples was studied. The stable passive region was observed and the dissolution mec...

  11. Monte Carlo Simulations of Coupled Diffusion and Surface Reactions during the Aqueous Corrosion of Borosilicate Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kerisit, Sebastien N.; Pierce, Eric M.; Ryan, Joseph V.

    2015-01-01

    Borosilicate nuclear waste glasses develop complex altered layers as a result of coupled processes such as hydrolysis of network species, condensation of Si species, and diffusion. However, diffusion has often been overlooked in Monte Carlo models of the aqueous corrosion of borosilicate glasses. Therefore, three different models for dissolved Si diffusion in the altered layer were implemented in a Monte Carlo model and evaluated for glasses in the compositional range (75-x) mol% SiO2 (12.5+x/2) mol% B2O3 and (12.5+x/2) mol% Na2O, where 0 ≤ x ≤ 20%, and corroded in static conditions at a surface-to-volume ratio of 1000 m-1. The three models considered instantaneous homogenization (M1), linear concentration gradients (M2), and concentration profiles determined by solving Fick’s 2nd law using a finite difference method (M3). Model M3 revealed that concentration profiles in the altered layer are not linear and show changes in shape and magnitude as corrosion progresses, unlike those assumed in model M2. Furthermore, model M3 showed that, for borosilicate glasses with a high forward dissolution rate compared to the diffusion rate, the gradual polymerization and densification of the altered layer is significantly delayed compared to models M1 and M2. Models M1 and M2 were found to be appropriate models only for glasses with high release rates such as simple borosilicate glasses with low ZrO2 content.

  12. Addition versus radiolytic production effects of hydrogen peroxide on aqueous corrosion of UO2

    International Nuclear Information System (INIS)

    The effects of hydrogen peroxide, H2O2, on UO2 corrosion is investigated in aerated deionized water in two types of situations. The H2O2 species is either added to water or produced by radiolysis at UO2/H2O interfaces. The concentrations vary in the range 10-5-10-1 mol l-1. The radiolysis is induced by irradiating the UO2/H2O interfaces with a He2+-beam emerging from the UO2 discs into the solutions. Both the evolution of the aqueous solutions and the UO2 surfaces are characterised. In both types of experiments, the alteration of UO2 results in the formation of the same secondary phase, an hydrated uranium peroxide called studtite (UO2(O)2 . 4H2O). However, the uranium release at the interface differs strikingly. It is much higher when H2O2 is produced by irradiation than when it is simply added. Furthermore, it varies in opposite direction as a function of the H2O2 concentration. This gives evidence that the chemistry at the UO2 interface under irradiation differs significantly from the chemistry induced by simply adding H2O2 to the solution. Rutherford backscattering spectrometry is used to determine the growth rate of the corrosion layer. For H2O2 addition, the layer thickness increases with increasing leaching time, although as time increases, the U release tends towards zero. It is possible to establish the first empirical equation relating the corrosion rates to the added H2O2 concentrations. For H2O2 radiolytic production, the growth is continuous as irradiation time increases but the growth rate seems to decrease as the layer grows and to reach a limit

  13. Comparison of corrosion behavior of ZL104 alloy at as-cast and heat treatment states

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The corrosion behavior of ZL 104 alloy at different states (as-cast and heat treatment) in salt spray corrosion (SSC) was studied. The results show that the sample treated after refinement and modification has the least corrosive resistance compared with the sample bearing as-cast structure at the beginning of the corrosion. As the corrosion process continued, however, the trend reversed itself. After 44 h continuous corrosion, the corrosive rates of all samples tend to be stable. After experiments, the sample bearing as-cast structure had the most corrosive products on the surface whereas the sample being refined and modified had the least products. The Fourier transformation infrared spectroscopy (FTIR)analyses of the corrosion products show that these products are composed of hydroxyl-containing substances.

  14. Corrosion fatigue behavior of zirconium in boiling nitric acid

    International Nuclear Information System (INIS)

    The corrosion fatigue behavior of zirconium in boiling nitric acid has been studied to evaluate the reliability of zirconium used in nuclear fuel reprocessing equipment. An apparatus designed for corrosion fatigue tests in boiling nitric acid was used. The crack growth rate of zirconium was measured as a function of the stress intensity factor using TDCB type specimens. After the tests, the fracture morphology was examined with a scanning electron microscope. The crack growth rate was influenced with the texture of specimens and the test environments. In air at room temperature, the crack growth rate at the longitudinal direction of specimens was faster than that of the transverse direction. Moreover, the crack growth rate in boiling nitric acid was more faster than that in air at room temperature. According to the fractographic examination, X-ray analysis, and so on, the observed results were interpreted with based on the crystal anisotropy on mechanical properties and the susceptibility to stress corrosion cracking in boiling nitric acid of zirconium. (author)

  15. Cathodic behavior of zirconium in aqueous solutions

    International Nuclear Information System (INIS)

    The electrochemical behavior of Zr was studied by polarization measurements. The surface oxide and zirconium hydride formed by cathodic polarization of Zr have been examined by X-ray, SEM, and a hardness tester. Zirconium hydride would form on Zr cathode after the surface oxide is reduced at the potential, which is several hundred mV more noble than the predicted value shown by the Pourbaix diagram. The parameters for the hydrogen evolution reaction on the hydride formed Zr cathode differs from that on the oxide covered surface, which means that hydrogen evolution takes place on both surfaces under a different mechanism, while details are still veiled at present

  16. Laser beam welding of Waspaloy: Characterization and corrosion behavior evaluation

    Science.gov (United States)

    Shoja Razavi, Reza

    2016-08-01

    In this work, a study on Nd:YAG laser welding of Waspaloy sheets has been made. Microstructures, phase changes and hardness of the laser joint were investigated using optical microscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD) and vickers microhardness (HV0.3). Corrosion behavior of the weldment at low temperature in 3.5%wt NaCl solution at room temperature was also investigated using open circuit potential and cyclic potentiodynamic polarization tests. Hot corrosion studies were conducted on samples in the molten salt environment (Na2SO4-60%V2O5) at 900 °C for 50 h. Results indicated that the microstructure of weld zone was mainly dendritic grown epitaxially in the direction perpendicular to the weld boundary and heat transfer. Moreover, the Ti-Mo carbide particles were observed in the structure of the weld zone and base metal. The average size of carbides formed in the base metal (2.97±0.5 μm) was larger than that of the weld zone (0.95±0.2 μm). XRD patterns of the weld zone and base metal showed that the laser welding did not alter the phase structure of the weld zone, being in γ-Ni(Cr) single phase. Microhardness profile showed that the hardness values of the weld zone (210-261 HV) were lower than that of the base metal (323-330 HV). Electrochemical and hot corrosion tests indicated that the corrosion resistance of the weld metal was greater than the base metal in both room and high temperatures.

  17. Panel report on corrosion in energy systems

    International Nuclear Information System (INIS)

    Corrosion problems in high-temperature (non aqueous) energy systems, corrosion in aqueous energy systems and institutional problems inhibiting the development of corrosion science and engineering are discussed

  18. Corrosion behavior of NiCrBSi coatings deposited by HVOF spraying

    Institute of Scientific and Technical Information of China (English)

    赵卫民; 王勇; 吴开源; 薛锦

    2003-01-01

    The corrosion resistance of NiCrBSi coating deposited on steel substrate by HVOF was examined using electrochemical tests and immersion tests so as to offer an experimental basis to expand a promising applied field of HVOF in aqueous medium, comparing with those of coatings deposited by oxyacetylene flame spraying and flame cladding. The results show that the general corrosion rate of HVOF sprayed coatings is quite bigger than that of clad coatings, but it is less sensitive to local corrosion. There is less and smaller porosity in the coatings deposited by HVOF than that in flame sprayed coatings. The effects of porosity on the corrosion current density was indistinctive, but the existence of large amount of defects in the coatings damaged the cohesion of the coatings, causing the metallic particles drop off from the coatings under the influence of corrosive medium. Improving the quality and reducing the porosity of coatings is the key to get the coatings with high corrosion resistance.

  19. 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%.

  20. Corrosion inhibitor activity of 1,3-diketone malonates for mild steel in aqueous hydrochloric acid solution

    International Nuclear Information System (INIS)

    Highlights: ► 1,3-Diketone malonates displayed relatively high corrosion inhibition efficiency. ► Inhibition efficiency is improved when temperature is increased within 25–55 °C. ► Corrosion inhibitor efficiency of diketone malonates is dependent on diketo population tautomer. ► Diketone malonates act as mixed corrosion inhibitors with a Langmuir isotherm. - Abstract: Four 1,3-diketone malonates compounds were synthesized and tested as corrosion inhibitors for mild steel in 1.0 M aqueous hydrochloric acid. Gravimetric and polarization tests showed that inhibitor efficiencies were related to molecular moiety and depended on tautomer concentration, i.e. enol–keto and diketo. Both tautomers displayed relatively high corrosion inhibition efficiency (75–96%) at 100 mg L−1, which increased with temperature (25–55 °C) and dependent on diketo population. Improvement in corrosion resistance was related to the presence of different substituent groups, from which hydrogen substituent contributed the most, apparently due to easiness of electron acceptance as confirmed by quantum chemical calculations.

  1. Corrosion behavior of zirconia in acidulated phosphate fluoride.

    Science.gov (United States)

    Thomas, Anie; Sridhar, Sathyanarayanan; Aghyarian, Shant; Watkins-Curry, Pilanda; Chan, Julia Y; Pozzi, Alessandro; Rodrigues, Danieli C

    2016-02-01

    Objective The corrosion behavior of zirconia in acidulated phosphate fluoride (APF) representing acidic environments and fluoride treatments was studied. Material and Methods Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM). Sample mass and dimensions were measured for mass loss determination. Samples were characterized by powder X-ray diffraction (XRD) to detect changes in crystallinity. A biosensor based on electrochemical impedance spectroscopy (EIS) was used to detect ion dissolution of material into the immersion media. Results Digital microscopy revealed diminishing luster of the materials and SEM showed increased superficial corrosion of zirconia submerged in 1.23% APF. Although no structural change was found, the absorption of salts (sodium phosphate) onto the surface of the materials bathed in 0.123% APF was significant. EIS indicated a greater change of impedance for the immersion solutions with increasing bathing time. Conclusion Immersion of zirconia in APF solutions showed deterioration limited to the surface, not extending to the bulk of the material. Inferences on zirconia performance in acidic oral environment can be elucidated from the study. PMID:27008257

  2. Corrosion behavior of zirconia in acidulated phosphate fluoride

    Science.gov (United States)

    Thomas, Anie; Sridhar, Sathyanarayanan; Aghyarian, Shant; Watkins-curry, Pilanda; Chan, Julia Y.; Pozzi, Alessandro; Rodrigues, Danieli C.

    2016-01-01

    ABSTRACT Objective The corrosion behavior of zirconia in acidulated phosphate fluoride (APF) representing acidic environments and fluoride treatments was studied. Material and Methods Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM). Sample mass and dimensions were measured for mass loss determination. Samples were characterized by powder X-ray diffraction (XRD) to detect changes in crystallinity. A biosensor based on electrochemical impedance spectroscopy (EIS) was used to detect ion dissolution of material into the immersion media. Results Digital microscopy revealed diminishing luster of the materials and SEM showed increased superficial corrosion of zirconia submerged in 1.23% APF. Although no structural change was found, the absorption of salts (sodium phosphate) onto the surface of the materials bathed in 0.123% APF was significant. EIS indicated a greater change of impedance for the immersion solutions with increasing bathing time. Conclusion Immersion of zirconia in APF solutions showed deterioration limited to the surface, not extending to the bulk of the material. Inferences on zirconia performance in acidic oral environment can be elucidated from the study. PMID:27008257

  3. Corrosion behavior of zirconia in acidulated phosphate fluoride

    Directory of Open Access Journals (Sweden)

    Anie Thomas

    2016-02-01

    Full Text Available ABSTRACT Objective The corrosion behavior of zirconia in acidulated phosphate fluoride (APF representing acidic environments and fluoride treatments was studied. Material and Methods Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM. Sample mass and dimensions were measured for mass loss determination. Samples were characterized by powder X-ray diffraction (XRD to detect changes in crystallinity. A biosensor based on electrochemical impedance spectroscopy (EIS was used to detect ion dissolution of material into the immersion media. Results Digital microscopy revealed diminishing luster of the materials and SEM showed increased superficial corrosion of zirconia submerged in 1.23% APF. Although no structural change was found, the absorption of salts (sodium phosphate onto the surface of the materials bathed in 0.123% APF was significant. EIS indicated a greater change of impedance for the immersion solutions with increasing bathing time. Conclusion Immersion of zirconia in APF solutions showed deterioration limited to the surface, not extending to the bulk of the material. Inferences on zirconia performance in acidic oral environment can be elucidated from the study.

  4. Microstructure, Bio-corrosion Behavior, and Corrosion Residual Strength of High Strain Rate Rolled Mg-4Zn Alloy Sheet

    Science.gov (United States)

    Zou, Zhengyang; Chen, Jihua; Yan, Hongge; Su, Bin; Gong, Xiaole

    2016-05-01

    Microstructure, bio-corrosion behavior, and corrosion residual strength in 0.9 wt.% NaCl solution of the fine-grained Mg-4Zn alloy sheet prepared by high strain rate rolling are systematically investigated. The as-rolled alloy has fine homogenous dynamic recrystallization grains with the average grain size of 4.5 μm. It has different bio-corrosion behavior from the as-cast and is the most corrosion resistant except for pure Mg. Its in vitro strength loss is about 19% after 7 days immersion (the as-cast, 62%), and corrosion residual strength after 15 days immersion is 205 MPa. Its in vitro strength loss after 15, 30, and 60 days immersion are 24, 37, and 38% respectively. The as-rolled Mg-4Zn alloy is featured with the slighter in vitro loss of mechanical integrity due to uniform bio-corrosion and is desirable for the usage in the field of bone fixation.

  5. Microstructure, Bio-corrosion Behavior, and Corrosion Residual Strength of High Strain Rate Rolled Mg-4Zn Alloy Sheet

    Science.gov (United States)

    Zou, Zhengyang; Chen, Jihua; Yan, Hongge; Su, Bin; Gong, Xiaole

    2016-04-01

    Microstructure, bio-corrosion behavior, and corrosion residual strength in 0.9 wt.% NaCl solution of the fine-grained Mg-4Zn alloy sheet prepared by high strain rate rolling are systematically investigated. The as-rolled alloy has fine homogenous dynamic recrystallization grains with the average grain size of 4.5 μm. It has different bio-corrosion behavior from the as-cast and is the most corrosion resistant except for pure Mg. Its in vitro strength loss is about 19% after 7 days immersion (the as-cast, 62%), and corrosion residual strength after 15 days immersion is 205 MPa. Its in vitro strength loss after 15, 30, and 60 days immersion are 24, 37, and 38% respectively. The as-rolled Mg-4Zn alloy is featured with the slighter in vitro loss of mechanical integrity due to uniform bio-corrosion and is desirable for the usage in the field of bone fixation.

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

    International Nuclear Information System (INIS)

    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

  7. Corrosion behavior of Hastelloy C-276 in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Qiang [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, P.O. Box 436, Chendu 610041 (China); Tang Rui [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, P.O. Box 436, Chendu 610041 (China)], E-mail: xajttr@163.com; Yin Kaiju; Luo Xin [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, P.O. Box 436, Chendu 610041 (China); Zhang Lefu [College of Nuclear Science and Technology, Shanghai Jiaotong University, Shanghai 200240 (China)

    2009-09-15

    The corrosion behavior of a nickel-based alloy Hastelloy C-276 exposed in supercritical water at 500-600 deg. C/25 MPa was investigated by means of gravimetry, scanning electron microscopy/energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. An oxide scale with dual-layer structure, mainly consisting of an outer NiO layer and an inner Cr{sub 2}O{sub 3}/NiCr{sub 2}O{sub 4}-mixed layer, developed on C-276 after 1000 h exposure. Higher temperature promoted oxidation, resulting in thicker oxide scale, larger weight gain and stronger tendency of oxide spallation. The oxide growth mechanism in SCW seems to be similar to that in high temperature water vapor, namely solid-state growth mechanism.

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

    International Nuclear Information System (INIS)

    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.

  9. Identification of Green Rust Compounds in the Aqueous Corrosion Processes of Steels; the Case of Microbially Induced Corrosion and Use of 78 K CEMS

    Science.gov (United States)

    Génin, J.-M. R.; Refait, Ph.; Olowe, A. A.; Abdelmoula, M.; Fall, I.; Drissi, S. H.

    1998-12-01

    Fe(II)-Fe(III) hydroxy-sulphate Green Rust 2, GR2(SO4 -), is obtained by microbially induced corrosion of steel. Transmission Mössbauer spectroscopy (TMS) was used to characterise the corrosion products of steel sheet piles under the biofilm at low sea-water level in a harbour. To understand the process, iron coupons maintained in aqueous solutions of 4 M NaCl and 0.1 M NaHCO3 of pH 7.4 were studied by X ray diffraction and conversion electron Mössbauer spectroscopy (CEMS) at 78 K. The Fe(II)-Fe(III) hydroxy-carbonate, GR1(CO3 -), covers the surface, as predicted by the Eh-pH diagram.

  10. Corrosion Fatigue Behavior of Duplex Stainless Steel in 3.5% Sodium Chloride Solution

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The corrosion fatigue behavior of duplex stainless steel (DSS) was studied at different cyclic stress levels in 3.5%NaCl (mass fraction, so as the follows) solution (pH=7) at 50℃. The results showed that DSS was susceptible to pitting corrosion and corrosion fatigue. Both intergranluar corrosion cracking and transgranlular corrosion cracking initiated at the bottom of pitting holes. Furthermore, the corrosion fatigue properties of DSS in 3.5%NaCl solution may be relatived to complex electrochemical and mechanical coupling effects between the three phases (austenite, ferrite and martensite), where martensite and ferrite were anodic in the corrosion cell and could be prone to cracking under certain condition.

  11. Behavior of copper corrosion products in water contours of power units

    International Nuclear Information System (INIS)

    Copper corrosion products (CP) solubility under state parameters of actual aqueous chemical regimes (ACR) whose sedimentations in the steam-generating sections (up to 85 % of the total amount) stimulate local corrosion types, is considered. The consideration from the viewpoint of equilibrium thermodynamics of chemical equilibria in multicomponent water-salt systems in their refraction for intracontour corrosion processes and mass transfer permits to obtain the missing information in the quiding materials on ACR and explains technical consequences of variations in the normalized parameters

  12. The Reinforcement Bond Strength Behavior under Different Corrosion Condition

    OpenAIRE

    Yousif A. Mansoor; Zhi Qiang Zhang

    2013-01-01

    The main idea of this study is to evaluate the bond strength for reinforcing concrete with corrosion that it can damage the R.C bond. Pullout tests carried out to evaluate the effects of corrosion on bond, for that purpose a series of specimens with varying reinforcement corrosion levels tested. The acceleration steel corrosion was 4, 6 and 8 days corrosion. The aim of choosing 4, 6 and 8 days that are trying to reflect field condition on test. The test designed to provide the data required t...

  13. Localized Corrosion of Mild Steel in a CO2 Aqueous Environment - a Review

    OpenAIRE

    Nešić, Srdjan

    2015-01-01

    Localized corrosion is a non-uniform loss of metal from the pipe wall which can lead to a loss of containment. Types of CO2 localized corrosion considered here include: pitting corrosion and so called mesa attack. The most common causes have been grouped into four categories, those related to: flow, chemical causes, metallurgical causes and biological causes. Localized CO2 corrosion mechanisms identified here include loss of protective layer, galvanic coupling, local water chemistry changes a...

  14. Effects of concentration of sodium chloride solution on the pitting corrosion behavior of AISI 304L austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Asaduzzaman M.D.

    2011-01-01

    Full Text Available The pitting corrosion behavior of the austenitic stainless steel in aqueous chloride solution was investigated using electrochemical technique. Corrosion potential (Ecorr measurement, potentiodynamic experiments, potential-hold experiments in the passive range, and microscopic examination were used for the evaluation of corrosion characteristics. The experimental parameters were chloride ion concentration, immersion time and anodic-hold potential. Ecorr measurements along with microscopic examinations suggest that in or above 3.5 % NaCl at pH 2 pitting took place on the surface in absence of applied potential after 6 hour immersion. The potentiodynamic experiment reveals that Ecorr and pitting potential (Epit decreased and current density in the passive region increased with the increase of chloride ion concentrations. A linear relationship between Epit and chloride ion concentrations was found in this investigation. The analysis of the results suggests that six chloride ions are involved for the dissolution of iron ion in the pitting corrosion process of austenitic stainless steel.

  15. Corrosion Behavior of Austenitic and Duplex Stainless Steels in Lithium Bromide

    OpenAIRE

    Ayo Samuel AFOLABI; Alaneme, K.K.; Samson Oluwaseyi BADA

    2009-01-01

    The corrosion behavior of austenitic and duplex stainless steels in various concentrations of lithium, bromide solution was investigated by using the conventional weight loss measurement method. The results obtained show that corrosion of these steels occurred due to the aggressive bromide ion in the medium. Duplex stainless steel shows a greater resistance to corrosion than austenitic stainless steel in the medium. This was attributed to equal volume proportion of ferrite and austenite in th...

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

    International Nuclear Information System (INIS)

    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 (Ea, A, ΔHa and ΔSa) 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

  17. Electrochemical corrosion behavior of steam turbine materials for geothermal power plants in simulated geothermal waters

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Haofeng [Shinshu Univ. (Japan). Graduate School; Niu Libin; Oishi, Shuji [Shinshu Univ. (Japan). Faculty of Engineering; Takaku, Hiroshi [Shinshu Univ. (Japan). Faculty of Engineering; Naigai Chemical Products Co. (Japan); Shiokawa, Kunio; Yamashita, Mitsuo; Sakai, Yoshihiro [Fuji Electric Advanced Technology Co., Ltd. (Japan)

    2007-08-15

    In order to evaluate the influence of chloride, sulfate and carbon dioxide in water on the electrochemical corrosion behavior of geothermal steam turbine materials, measurements of the anodic polarization and the pitting corrosion potential were conducted in simulated geothermal waters. The corrosion resistance of all materials tested was lowered by an increasing carbon dioxide content in the simulated geothermal waters. Higher chloride concentrations in the waters induced lower corrosion resistance and also lower pitting corrosion potentials for materials with higher chromium contents, suggesting the corrosion behavior was mainly controlled by the chromium content of the materials. The corrosion resistance of 9CrMoV and 13Cr steels was also influenced by the concentration of sulfate in the water. The improved heat-treated 16Cr-4Ni material for turbine blades showed excellent corrosion resistance. In the presence of sulfate, the corrosion reactions are mitigated due to a decreasing concentration of chloride (due to the presence of sulfate) in corrosion pits. (orig.)

  18. RHEOLOGICAL BEHAVIOR OF ERWINIA GUM IN AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    Li-na Zhang; Mei Zhang; Jing-hua Chen; Hideki Iijima; Hiromichi Tsuchiya

    1999-01-01

    Erwinia (E) gum, an extracellular polysaccharide, is composed of fucose, galatose, glucose and glucuronic acid. Its viscosity behavior was investigated by a low-shear-rate multiball viscometer and a rotational viscometer. Its weight-average molecular weight Mw and intrinsic viscosity [η] in 0.2 mol/L NaCl aqueous solution were measured by light scattering method at 35℃ and viscometry at 25℃ and found to be 1.06 × 106 g/mol and 1050 mL/g, respectively, and its aggregates in aqueous solution were proved by gel permeation chromatography (GPC). These results indicated that E gum in water has exceedingly high viscosity and exhibits Binham fluid behavior, owing to its aggregation. The viscosity of E gum decreased with increasing temperature, and the turning point appeared at 38℃ for dilute solution and 80℃ for concentrated solution suggesting that the aggregates of E gum in water started to disaggregate under these temperatures. In addition, the aggregates can be disrupted by adding either acid or base. The experimental results indicated that the E gum is a good thickening agent, and its fluid behavior is similar to xanthan.

  19. Effect of Heat Treatment on the Corrosion Behavior of Nickel Chromium (Wiron 99) Alloys

    OpenAIRE

    Supreetha SN; Ravindra K.; Murali H

    2010-01-01

    The purpose of this study was to evaluate the corrosion behavior of Nickel chromium alloys (Wiron 99) in the as-cast condition and when subjected to different firing temperatures. This information is important as the firing porcelain on the metal substructure of a restoration may produce changes in corrosion behavior that could influence an alloy behavior during long term use. This study was also designed to study comprehensively the clinical serviceability of these Nickel chromium alloys.

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

    International Nuclear Information System (INIS)

    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 Ag3Sn islands in the Cu-rich matrix which decrease the cathode/anode ratio of microgalvanic cells

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

    Energy Technology Data Exchange (ETDEWEB)

    Salehisaki, Mehdi, E-mail: mehdisasaki@ut.ac.ir [Department of Materials Science and Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Aryana, Maryam, E-mail: maryam.aryana@yahoo.com [AGSP Engineering Company, Biomaterial Research Unit, R.N: 12786 Kerman (Iran, Islamic Republic of)

    2014-04-01

    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{sub 3}Sn islands in the Cu-rich matrix which decrease the cathode/anode ratio of microgalvanic cells.

  2. Effect of N addition on tensile and corrosion behaviors of CD4MCU cast duplex stainless steels

    Science.gov (United States)

    Son, Jinil; Kim, Sangshik; Lee, Jehyun; Choi, Byunghak

    2003-08-01

    The effect of N addition on the microstructure, tensile, and corrosion behaviors of CD4MCU (Fe-25Cr-5Ni-2.8Cu-2Mo) cast duplex stainless steel was examined in the present study. The slow strain rate tests were also conducted at a nominal strain rate of 1 × 10-6/s in air and 3.5 pct NaCl+5 pct H2SO4 solution for studying the stress corrosion cracking (SCC) behavior. It was observed that the volume fraction of austenitic phase in CD4MCU alloy varied from 38 to 59 pct with increasing nitrogen content from 0 to 0.27 wt. pct. The tensile behavior of CD4MCU cast duplex stainless steels, which tended to vary significantly with different N contents, appeared to be strongly related to the volume changes in ferritic and austenitic phases, rather than the intrinsic N effect. The improvement in the resistance to general corrosion in 3.5 pct NaCl+5 pct H2SO4 aqueous solution was notable with 0.13 pct N addition. The further improvement was not significant with further N addition. The resistance to SCC of CD4MCU cast duplex stainless steels in 3.5 pct NaCl+5 pct H2SO4 aqueous solution, however, increased continuously with increasing N content. The enhancement in the SCC resistance was believed to be related to the volume fraction of globular austenitic colonies, which tended to act as barriers for the development of initial pitting cracks in the ferritic phase into the sharp ones.

  3. Solid state and aqueous behavior of uranyl peroxide cage clusters

    Science.gov (United States)

    Pellegrini, Kristi Lynn

    Uranyl peroxide cage clusters include a large family of more than 50 published clusters of a variety of sizes, which can incorporate various ligands including pyrophosphate and oxalate. Previous studies have reported that uranyl clusters can be used as a method to separate uranium from a solid matrix, with potential applications in reprocessing of irradiated nuclear fuel. Because of the potential applications of these novel structures in an advanced nuclear fuel cycle and their likely presence in areas of contamination, it is important to understand their behavior in both solid state and aqueous systems, including complex environments where other ions are present. In this thesis, I examine the aqueous behavior of U24Pp 12, as well as aqueous cluster systems with added mono-, di-, and trivalent cations. The resulting solutions were analyzed using dynamic light scattering and ultra-small angle X-ray scattering to evaluate the species in solution. Precipitates of these systems were analyzed using powder X-ray diffraction, X-ray fluorescence spectrometry, and Raman spectroscopy. The results of these analyses demonstrate the importance of cation size, charge, and concentration of added cations on the aqueous behavior of uranium macroions. Specifically, aggregates of various sizes and shapes form rapidly upon addition of cations, and in some cases these aggregates appear to precipitate into an X-ray amorphous material that still contains U24Pp12 clusters. In addition, I probe aggregation of U24Pp12 and U60, another uranyl peroxide cage cluster, in mixed solvent water-alcohol systems. The aggregation of uranyl clusters in water-alcohol systems is a result of hydrogen bonding with polar organic molecules and the reduction of the dielectric constant of the system. Studies of aggregation of uranyl clusters also allow for comparison between the newer uranyl polyoxometalate family and century-old transition metal polyoxometalates. To complement the solution studies of uranyl

  4. Effect of Sulfate Reduced Bacterium on Corrosion Behavior of 10CrMoAl Steel

    Institute of Scientific and Technical Information of China (English)

    WANG Hua; LIANG Cheng-hao

    2007-01-01

    The effects of sulfate reduced bacterium (SRB) on the corrosion behavior of 10CrMoAl steel in seawater were studied by chemical immersion, potentiodynamic polarization, electrochemical impedance spectroscopy measurement, and scanning electron microscope techniques. The results show that the content of element sulfur in the corrosion product of 10CrMoAl steel in seawater with SRB is up to 9.23%, which is higher than that of the same in sterile seawater. X-ray diffraction demonstrates that the main corrosion product is FeS. SRB increases the corrosion rate by anodic depolarization of the metabolized sulfide product. SEM observation indicates that the corrosion product is not distributed continuously; in addition, bacilliform sulfate-reduced bacterium accumulates on the local surface of 10CrMoAl steel. Hence, SRB enhances sensitivity to the localized corrosion of 10CrMoAl steel in seawater.

  5. Corrosion behavior of carbon steel in wet Na-bentonite medium

    International Nuclear Information System (INIS)

    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)

  6. Effects of aging treatment on the intergranular corrosion behavior of Al–Cu–Mg–Ag alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiao Yan, E-mail: x918y@126.com; Li, Meng Jie; Gao, Fei; Liang, Shun Xing; Zhang, Xi Liang; Cui, Hao Xuan

    2015-08-05

    Highlights: • Corrosion resistance of Al–Cu–Mg–Ag alloy follows: under-aged > peak-aged > over-aged. • The simulated matrix, θ (Al{sub 2}Cu), and the precipitations free zones (PFZ) were prepared. • The self-corrosion potentials satisfy E{sub Matrix} > E{sub θ} > E{sub PFZ}. • The wider PFZ is adverse to the corrosion resistance of Al–Cu–Mg–Ag alloy. - Abstract: The effects of aging treatment on the corrosion behavior of Al–Cu–Mg–Ag alloy were studied by means of intergranular corrosion (IGC) testing, potentiodynamic polarization combined with optical microscopy (OM) and transmission electron microscopy (TEM). Corrosion testing results suggest that, the intergranular corrosion resistance properties of Al–Cu–Mg–Ag alloy decreased with increasing aging time, which is also corroborated by the potentiodynamic polarization test results for under-aged, peak-aged and the over-aged Al–Cu–Mg–Ag alloys. TEM results reveal that precipitations on the grain boundary became coarsened and distributed discontinuously with increasing aging time; widening of precipitation free zones (PFZ) is also observed. The PFZ with the lowest self-corrosion potential is preferentially attacked, and corrosion progresses along the PFZ. The corrosion resistance of over-aged Al–Cu–Mg–Ag alloy decreased because of its wider PFZ in comparison with those in other samples.

  7. Effects of aging treatment on the intergranular corrosion behavior of Al–Cu–Mg–Ag alloy

    International Nuclear Information System (INIS)

    Highlights: • Corrosion resistance of Al–Cu–Mg–Ag alloy follows: under-aged > peak-aged > over-aged. • The simulated matrix, θ (Al2Cu), and the precipitations free zones (PFZ) were prepared. • The self-corrosion potentials satisfy EMatrix > Eθ > EPFZ. • The wider PFZ is adverse to the corrosion resistance of Al–Cu–Mg–Ag alloy. - Abstract: The effects of aging treatment on the corrosion behavior of Al–Cu–Mg–Ag alloy were studied by means of intergranular corrosion (IGC) testing, potentiodynamic polarization combined with optical microscopy (OM) and transmission electron microscopy (TEM). Corrosion testing results suggest that, the intergranular corrosion resistance properties of Al–Cu–Mg–Ag alloy decreased with increasing aging time, which is also corroborated by the potentiodynamic polarization test results for under-aged, peak-aged and the over-aged Al–Cu–Mg–Ag alloys. TEM results reveal that precipitations on the grain boundary became coarsened and distributed discontinuously with increasing aging time; widening of precipitation free zones (PFZ) is also observed. The PFZ with the lowest self-corrosion potential is preferentially attacked, and corrosion progresses along the PFZ. The corrosion resistance of over-aged Al–Cu–Mg–Ag alloy decreased because of its wider PFZ in comparison with those in other samples

  8. Corrosion behavior of oil tube steel in simulant solution with hydrogen sulfide and carbon dioxide

    International Nuclear Information System (INIS)

    Electrochemical measurement techniques, X-ray diffraction and scanning electron microscopy were applied to investigate the corrosion behavior of N80 tube steel in simulant static solution with carbon dioxide (CO2) and hydrogen sulfide (H2S) at a temperature of 100 deg. C. Sweet corrosion occurred when a very small partial pressure of H2S was added. At this condition, uniform corrosion was found. The added H2S only accelerated the general corrosion rate. Sour corrosion was primary as the partial pressure of H2S increased to 0.010 MPa. The general corrosion rate decreased quickly, but severe pitting was found. The corrosion scale, mainly composed of coarse grains of mackinawite (FeS1-x), was loose and brittle. In sour corrosion, general corrosion rate decreased slowly and pitting became slight with increasing partial pressure of H2S because the primary corrosion product, fine grains of pyrrhotite (FeS1+x), made the scale more compact and continuous

  9. Corrosion Inhibition of Aluminum in Acidic Solution by Aqueous Extract of Ajowan Plant as Green Inhibitor

    OpenAIRE

    Aisha M. Al-Turkustani; Mona M. Al-Solmi

    2011-01-01

    The inhibition of aluminum corrosion in 0.5 M hydrochloric acid by Ajowan plant was studied using chemical (weight loss) and ectrochemical (impedance and polarization) methods. The Ajowan plant extract was found to be good inhibitor for aluminum corrosion in 0.5 M hydrochloric acid in the studied concentration range of inhibitor. Corrosion inhibition could be explained by considering an interaction between metal surface and the inhibitor molecules. Electrochemical measurements showed that Ajo...

  10. Preparation and corrosion behavior evaluation of amalgam/titania nano composite

    Directory of Open Access Journals (Sweden)

    Neda Bahremandi Tolou

    2011-01-01

    Conclusion: By adding nano particles of titania and preparing amalgam/titania nano composite as a dental amalgam, corrosion behavior and mercury release during the 2 st h after preparation could be improved.

  11. Corrosion resistance behavior of nitrogen ion-implanted in tantalum

    Science.gov (United States)

    Ramezani, Amir Hoshang; Hantehezadeh, Mohammad Reza; Ghoranneviss, Mahmood; Darabi, Elham

    2016-03-01

    This paper investigates the effect of nitrogen ion implantation on surface structure as well as resistance against tantalum corrosion. In this experiment, nitrogen ions which had energy of 30 keV and were in doses of 1 × 1017 to 9 × 1017 ions/cm2 were used. The X-ray diffraction analysis was applied for both the metallic analysis and the study of new structures having been created through the nitrogen ion implantation. Atomic force microscopy was also used to check the roughness variations prior to and also after the implantation phase. Moreover, the corrosion analysis apparatus was applied in order to compare resistance against tantalum corrosion in advance to and after the ion implantation. The results indicate that nitrogen ion implantation has a significant impact on increasing resistance against tantalum corrosion. After the corrosion test, the surface morphology of samples was analyzed by scanning electron microscopy. Also, the elemental composition is characterized by energy-dispersive X-ray (EDX) analysis. The purpose of this article is to obtain the perfect condition of the formation of tantalum corrosion resistance. The corrosion potential curves and roughness values obviously indicate that corrosion potential variations caused by the different doses of nitrogen ion bombardment are proportional to surface roughness in an inverse manner. The EDX analysis demonstrates the existence of the elemental composition of nitrogen ion implantation in the samples.

  12. Microstructure and corrosion behavior of hot-rolled GCr15 bearing steel

    Science.gov (United States)

    Fu, Junwei

    2016-04-01

    Microstructure, corrosion behavior and evolution of hot-rolled high-carbon-chromium bearing steel were investigated using scanning electron microscopy and energy dispersive spectrometer (EDS). The results show that corrosion initiates adjacent to the network carbide, which is the initial austenite grain boundary. With the further increase in corrosion time, corrosion fraction is increased and extended into the grains. Finally, the whole grain near the network carbide is etched off and the grain boundary is detached from the sample, which forms the corroded holes. Based on the EDS analyses, it is confirmed that this corrosion behavior is resulted from the depletion of Cr as solid solute at the grain boundary. The depletion of Cr is the result of the formation of Cr carbide near the grain boundary.

  13. Evaluating the Hot Corrosion Behavior of High-Temperature Alloys for Gas Turbine Engine Components

    Science.gov (United States)

    Deodeshmukh, V. P.

    2015-11-01

    The hot corrosion behavior of high-temperature alloys is critically important for gas turbine engine components operating near the marine environments. The two test methods—Two-Zone and Burner-Rig—used to evaluate the hot corrosion performance of high-temperature alloys are illustrated by comparing the Type I hot corrosion behavior of selected high-temperature alloys. Although the ranking of the alloys is quite comparable, it is evident that the two-zone hot corrosion test is significantly more aggressive than the burner-rig test. The effect of long-term exposures and the factors that influence the hot corrosion performance of high-temperature alloys are briefly discussed.

  14. Corrosion fatigue behavior of carbon steel in drilling fluids

    Energy Technology Data Exchange (ETDEWEB)

    Chaoyang, F.; Jiashen, Z. [Huazhong Univ. of Science and Technology, Wuhan (China)

    1998-08-01

    Corrosion fatigue of carbon steel (CS) in drilling fluids was studied using a self-made rotary bending corrosion fatigue testing apparatus under simulated drilling conditions. Mechanisms of the effects of cyclic stress, chloride (Cl{sup {minus}}), sulfide (S{sup 2{minus}}), and pH of drilling fluids on corrosion fatigue of CS as well as the inhibiting action of the imidazoline inhibitor and oxygen (O{sub 2}) scavenger sodium sulfite (Na{sub 2}SO{sub 3}) on corrosion fatigue were studied. Results showed Cl{sup {minus}} and S{sup 2{minus}} promoted corrosion fatigue crack initiation and growth. Fatigue life was lengthened after reducing subjected stress, increasing the pH of the drilling fluids, or adding the inhibitor and O{sub 2} scavenger.

  15. Corrosion and Stress Corrosion Behaviors of Low and Medium Carbon Steels in Agro-Fluid Media

    Directory of Open Access Journals (Sweden)

    Ayo Samuel AFOLABI

    2007-01-01

    Full Text Available Investigations were carried out to study critically the corrosion behaviour and Stress Corrosion Cracking (SCC of low and medium carbon steels in cassava and cocoa extracts by weight loss measurement and constant extension to fracture method respectively. The results obtained showed that medium carbon steel is more susceptible to corrosion than low carbon steel in both media. SCC is also more in medium carbon steel than low carbon steel in the two media under study. These deductions are due to higher carbon content in medium carbon steel coupled with various aggressive corrosion constituents contained in these media. Hydrogen embrittlement, as well as carbon cracking, is responsible for SCC of these materials in the agro-fluid media.

  16. Microbially influenced corrosion of stainless steel by marine bacterium Vibrio natriegens: (I) Corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Sha; Tian Jintao [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Chen Shougang, E-mail: sgchen@ouc.edu.cn [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Lei Yanhua; Chang Xueting; Liu Tao [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Yin Yansheng, E-mail: yys2006@ouc.edu.cn [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China)

    2009-04-30

    The microbially influenced corrosion of stainless steel (SS) by marine bacterium Vibrio natriegens (V. natriegens) was investigated using surface analysis (atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDXA)) and electrochemical techniques (the open circuit potential, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization curves ). AFM images corroborated the results from the EIS models which show biofilm attachment and subsequent detachment over time. The SEM images revealed the occurrence of micro-pitting corrosion underneath the biofilms on the metal surface after the biofilm removal. The presence of carbon, oxygen, phosphor and sulfur obtained from EDXA proved the formation of biofilm. The electrochemical results showed that the corrosion of SS was accelerated in the presence of V. natriegens based on the decrease in the resistance of the charge transfer resistance (R{sub ct}) obtained from EIS and the increase in corrosion current densities obtained from potentiodynamic polarization curves.

  17. Microbially influenced corrosion of stainless steel by marine bacterium Vibrio natriegens: (I) Corrosion behavior

    International Nuclear Information System (INIS)

    The microbially influenced corrosion of stainless steel (SS) by marine bacterium Vibrio natriegens (V. natriegens) was investigated using surface analysis (atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDXA)) and electrochemical techniques (the open circuit potential, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization curves ). AFM images corroborated the results from the EIS models which show biofilm attachment and subsequent detachment over time. The SEM images revealed the occurrence of micro-pitting corrosion underneath the biofilms on the metal surface after the biofilm removal. The presence of carbon, oxygen, phosphor and sulfur obtained from EDXA proved the formation of biofilm. The electrochemical results showed that the corrosion of SS was accelerated in the presence of V. natriegens based on the decrease in the resistance of the charge transfer resistance (Rct) obtained from EIS and the increase in corrosion current densities obtained from potentiodynamic polarization curves.

  18. Applications of cathodic protection for the protection of aqueous and soil corrosion of power plant components

    International Nuclear Information System (INIS)

    Power plant components exposed to environments such as water and soil are susceptible to severe corrosion. Many times the effect of corrosion in power plant components can be catastrophic. The problem is aggravated for underground pipelines due to additional factors such as large network of pipelines, proximity to earth mat, high voltage transmission lines, corrosive chemicals, inadequate approach etc. Other components such as condenser water boxes, internals of pipelines, clarifier bridge structures, cooling water inlet gates and pipes etc. which are in continuous contact with water, are subjected to severe corrosion. The nature and locations of all such components are at places which are not accessible for routine maintenance and hence they require long term reliable protection against corrosion. Experience has shown that anti-corrosive coatings are inadequate in preventing corrosion and due to their location regular maintenance coatings are also not feasible. Under such circumstances the applications of cathodic protection provides a long term solution the design of cathodic protection, for such applications differs from the commonly employed cathodic protection for cross-country pipelines and submerged structures due to other complexities in the plant region and maintenance of the applied system. The present paper intends to discuss the applications of cathodic protection with suitable anti-corrosive coatings for protection of various power plant components and the specific features of each type of application. (author)

  19. Aqueous corrosion of silicate glasses. Analogy between volcanic glasses and the French nuclear waste glass R7T7

    International Nuclear Information System (INIS)

    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

  20. NF ISO 10270. Corrosion of metals and alloys. Aqueous corrosion tests of zirconium alloys used in nuclear reactors

    International Nuclear Information System (INIS)

    This international standard prescribes the determination of the mass gain and the superficial control of zirconium and zirconium alloy products after a corrosion test performed in water at 360 deg. C and in steam at 400 deg. C or more. A pressure of 10.3 MPa (1500 psi) is applied during the tests performed in vapor. This standard applies to welded and molded products, to powder metallurgy products and to filler metals for welding application. The method has been widely used in the development of new alloys and new techniques of thermal treatment and in the evaluation of welding techniques. (J.S.)

  1. Corrosion behavior of pure titanium in the presence of Actinomyces naeslundii.

    Science.gov (United States)

    Zhang, Song-Mei; Qiu, Jing; Tian, Fei; Guo, Xiao-Kui; Zhang, Fu-Qiang; Huang, Qing-Feng

    2013-05-01

    It is well known that some microorganisms affect the corrosion of dental metal. Oral bacteria such as Actinomyces naeslundii may alter the corrosion behavior and stability of titanium. In this study, the corrosion behavior of titanium was studied in a nutrient-rich medium both in the presence and the absence of A. naeslundii using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). A. naeslundii was able to colonize the surface of titanium and then form a dense biofilm. The SEM images revealed the occurrence of micropitting corrosion on the metal surface after removal of the biofilm. The electrochemical corrosion results from EIS showed a significant decrease in the corrosion resistant (R(p)) value after immersing the metal in A. naeslundii culture for 3 days. Correspondingly, XPS revealed a reduction in the relative levels of titanium and oxygen and an obvious reduction of dominant titanium dioxide (TiO₂) in the surface oxides after immersion of the metal in A. naeslundii culture. These results suggest that the metabolites produced by A. naeslundii can weaken the integrity and stability of the protective TiO₂ in the surface oxides, which in turn decreases the corrosion resistance of titanium, resulting in increased corrosion of titanium immersed in A. naeslundii solution as a function of time. PMID:23430335

  2. Corrosion-electrochemical behavior of 13% chromium (Cr) martensitic stainless steel in hydrochloric acid (HCl) solutions

    International Nuclear Information System (INIS)

    Corrosion-electrochemical behavior of commercial API5CT grade L80 type tubing made of 13Cr martensitic stainless steel enriched with microalloying elements is studied in 6, 7.5, 9, 12 and 15% HCl solutions by electrochemical methods. The corrosion morphology was examined by means of EDAX scanning electron microscope (SEM) coupled with an ESCA analyzer. The soluble corrosion products were analyzed by atomic absorption spectroscopy and colorimetric methods. General, as well as localized, corrosion is present. The severest general corrosion with a maximum rate of 26 mm/year is obtained at 15% HCl. The localized corrosion which morphologically differs as function of HCl concentrations is revealed by SEM investigation. In all the above HCl solutions, the commercial 13% Cr martensitic stainless steel tubing shows no passive state. Above 6% HCl, the microalloying elements promote forming a discontinuous film of the corrosion products. The corrosion rate slightly decreases in 15% HCl compared to the published data on a conventional 13% Cr martensitic stainless steel tubing. This is due to both the chemical composition (silicon, manganese and vanadium) and microstructural properties. Copper seems to additionally accelerate the corrosion of the alloy

  3. Corrosion Behavior of Pure Cr, Ni, and Fe Exposed to Molten Salts at High Temperature

    Directory of Open Access Journals (Sweden)

    O. Sotelo-Mazón

    2014-01-01

    Full Text Available Corrosion resistance of pure Fe, Cr, and Ni materials exposed in NaVO3 molten salt at 700°C was evaluated in static air during 100 hours. The corrosion resistance was determined using potentiodynamic polarization, open circuit potential, and lineal polarization resistance. The conventional weight loss method (WLM was also used during 100 hours. The electrochemical results showed that Fe and Cr have a poor corrosion resistance, whereas pure Ni showed the best corrosion performance, which was supported by the passive layer of NiO formed on the metallic surface and the formation of Ni3V2O8 during the corrosion processes, which is a refractory compound with a higher melting point than that of NaVO3, which reduces the corrosivity of the molten salt. Also, the behavior of these materials was associated with the way in which their corresponding oxides were dissolved together with their type of corrosion attack. Through this study, it was confirmed that when materials suffer corrosion by a localized processes such as pitting, the WLM is not reliable, since a certain amount of corrosion products can be kept inside the pits. The corroded samples were analyzed through scanning electron microscopy.

  4. Susceptibility of 17-4PH stainless steel to stress corrosion cracking in aqueous environments by electrochemical techniques

    International Nuclear Information System (INIS)

    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 Na2SO4. 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)

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

    International Nuclear Information System (INIS)

    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

  6. Assessment of E110 and E635 alloy corrosion behavior in VVER - 1200 reactors

    International Nuclear Information System (INIS)

    In Russia the work is currently under way to design higher power light water reactors of longer operation (VVER-1200 type) which entails more rigid conditions for the operation of fuel claddings and other Zirconium FA components and, hence, more rigid requirements for their corrosion properties. To validate and predict the corrosion behavior of available and promising Zr alloys in VVER-1200 a comparative analysis has to be carried on of the operation conditions of Zirconium fuel elements of standard VVER-1000 and promising VVER-1200 to elucidate the factors that are responsible for the corrosion behavior of Zirconium alloys as well as of the conditions by those factors into the general corrosion have to be assessed using the results of out- of and in-pile investigations. The paper discusses the results of out- of and in-pile tests studying the corrosion properties of E110 and E635 Zirconium alloy components in light water commercial and research reactors of different types. An empiric dependence of the corrosion behavior of E110 and E635 Zirconium alloys was developed as applied to the conditions of the VVER type reactor operation conditions. Using the signed empiric dependence the E110 and E635 alloy corrosion in the VVER-1200 reactor was pre-assessed. (authors)

  7. The Corrosion Characteristics and Tensile Behavior of Reinforcement under Coupled Carbonation and Static Loading

    Directory of Open Access Journals (Sweden)

    Yidong Xu

    2015-12-01

    Full Text Available This paper describes the non-uniform corrosion characteristics and mechanical properties of reinforcement under coupled action of carbonation and static loading. The two parameters, namely area-box (AB value and arithmetical mean deviation (Ra, are adopted to characterize the corrosion morphology and pitting distribution from experimental observations. The results show that the static loading affects the corrosion characteristics of reinforcement. Local stress concentration in corroded reinforcement caused by tensile stress drives the corrosion pit pattern to be more irregular. The orthogonal test results from finite element simulations show that pit shape and pit depth are the two significant factors affecting the tensile behavior of reinforcement. Under the condition of similar corrosion mass loss ratio, the maximum plastic strain of corroded reinforcement increases with the increase of Ra and load time-history significantly.

  8. Microstructure and Corrosion Behavior of Hot-Deformed and Cold-Strained High-Mn Steels

    Science.gov (United States)

    Grajcar, A.; Kciuk, M.; Topolska, S.; Płachcińska, A.

    2016-06-01

    The electrochemical corrosion properties of 26Mn-3Si-3Al and 27Mn-4Si-2Al austenitic steels in two different states were studied in 0.1 M H2SO4 and 3.5% NaCl using potentiodynamic polarization tests. The effect of cold deformation on the microstructure and corrosion behavior of steels was analyzed. In acid solution, both steels exhibited lower corrosion resistance than in chloride solution independently on the steel state (hot-rolled, cold-worked). Cold deformation decreases the corrosion resistance, though this effect is smaller than the effect of chemical composition related to the combined Al + Si addition. All steels showed the evidence of pitting corrosion. The intensive dissolution of Fe and Mn takes place in the acid medium.

  9. Effects of High Magnetic Field on Solidification and Corrosion Behaviors of Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The solidification behaviors of AZ61 magnesium alloy under a high magnetic field were studied. The corrosion property of AZ61 alloy was investigated in a solution of 3.5 mol/L NaCl by measuring electrochemical polarization. The results show that the high magnetic field can refine microstructure and benefit aluminum transfer.The crystal of α-Mg is induced to orient with their c-axis parallel to the magnetic field. The corrosion studies indicate that different crystal plane of magnesium has different corrosion property. The passivating films on the a- and b-planes have higher corrosion resistance than that on the c-plane. Aligned structure affects the corrosion property of AZ61 magnesium alloy.

  10. 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.)

  11. Corrosion Behavior of Al-Brass in hydrofluoric Acid and Sulphuric Acid

    International Nuclear Information System (INIS)

    The corrosion rate of Al-brass in hydrofluoric acid and sulphuric acid were measured and examined. Mutual interaction of corrosion inhibition was appeared by addition of sulphuric acid to hydrofluoric acid. The inhibition behavior was a function of concentration and temperature. Addition of 60% sulphuric acid to hydrofluoric acid appeared an effective good inhibition of Al-brass corrosion at 30 .deg. - 50 .deg. C. The corrosion activation energy of Al-brass in 47%-HF was obtained as 12.6 Kcal/mol and in 40%-HF + 60% H2SO4 was obtained as 4.6 Kcal/mol from Arrhenius plot. From the value of the apparent activation energy it was indicated that chemical reaction was rate determination step in 47%-HF and physical diffusion was rate determination step in 40% HF + 60% H2SO4. Addition of sulphuric acid to hydrofluoric acid decreased a sensitivity of temperature to corrosion reaction

  12. Erosion-Corrosion Behavior of Power Plant Pipe Caused by Hot Feed Water

    International Nuclear Information System (INIS)

    In this study, we tried to define the erosion-corrosion behavior together with the resulting effects on a pipe that is a part of a feed water circulation system according to the pipe size and hot feed water environment. An erosion corrosion analysis was performed through the Hayduk and Minas model based on the chemical reaction between iron and oxygen, an essential corrosive factor. The erosion-corrosion rate against the pipe diameter and feed water temperature was then evaluated by means of finite element analysis using Abacus. As shown in the results, the feed water temperature was the main factor influencing the erosion-corrosion rate; in particular, it was expected that the thickness of 316 stainless steel would decrease by 2.59 μm every year in a hot water environment at 290 .deg. C

  13. Corrosion behavior of pure aluminum in FeCl3 solution

    Institute of Scientific and Technical Information of China (English)

    QU Jun-e; GUO Xing-peng; WANG Hai-ren; HUANG Jin-ying

    2006-01-01

    The corrosion behavior of pure aluminum in FeCl3 solution was investigated mainly by in-situ AFM (Atomic Force Microscopy). The results of combined researches of AFM, SEM(Scanning Electron Microscopy) and EDAX(Energy Dispersive Analysis of X-ray) show that in addition to uniform attack, pitting corrosion takes place also on pure aluminum surface in FeCl3solution at open-circuit potential, and impurity elements Fe and Cu are found enriched in corrosion product. In-situ AFM was also used to examine the initiation and development of pitting corrosion of pure aluminum induced by potentiodynamic sweep, and the repassivation of an active pit is observed. AFM tip scratching technique was used to produce a physical defect on metal surface,which is traced by in-situ AFM and it is found that the defect is likely to be preferentially attacked and evolve to pitting corrosion.

  14. Corrosion Behavior of Carbon Steel in Synthetically Produced Oil Field Seawater

    Directory of Open Access Journals (Sweden)

    Subir Paul

    2014-01-01

    Full Text Available The life of offshore steel structure in the oil production units is decided by the huge corrosive degradation due to SO42-, S2−, and Cl−, which normally present in the oil field seawater. Variation in pH and temperature further adds to the rate of degradation on steel. Corrosion behavior of mild steel is investigated through polarization, EIS, XRD, and optical and SEM microscopy. The effect of all 3 species is huge material degradation with FeSx and FeCl3 and their complex as corrosion products. EIS data match the model of Randle circuit with Warburg resistance. Addition of more corrosion species decreases impedance and increases capacitance values of the Randle circuit at the interface. The attack is found to be at the grain boundary as well as grain body with very prominent sulphide corrosion crack.

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

    Directory of Open Access Journals (Sweden)

    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.

  16. Corrosion Behavior of Alloy 22 in Chloride Solutions Containing Organic Acids

    Energy Technology Data Exchange (ETDEWEB)

    Carranza, R M; Giordano, C M; Rodr?guez, M A; Rebak, R B

    2005-11-04

    Alloy 22 (N06022) is a nickel based alloy containing alloying elements such as chromium, molybdenum and tungsten. It is highly corrosion resistant both under reducing and under oxidizing conditions. Electrochemical studies such as electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 in 1M NaCl solutions at various pH values from acidic to neutral at 90 C. Tests were also carried out in NaCl solutions containing oxalic acid or acetic acid. It is shown that the corrosion rate of Alloy 22 was higher in a solution containing oxalic acid than in a solution of the same pH acidified with HCl. Acetic acid was not corrosive to Alloy 22. The corrosivity of oxalic acid was attributed to its capacity to form stable complex species with metallic cations from Alloy 22.

  17. Corrosion behavior of niobium coated 304 stainless steel in acid solution

    Science.gov (United States)

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

    2016-04-01

    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.

  18. Microstructure and Corrosion Behavior of Hot-Deformed and Cold-Strained High-Mn Steels

    Science.gov (United States)

    Grajcar, A.; Kciuk, M.; Topolska, S.; Płachcińska, A.

    2016-04-01

    The electrochemical corrosion properties of 26Mn-3Si-3Al and 27Mn-4Si-2Al austenitic steels in two different states were studied in 0.1 M H2SO4 and 3.5% NaCl using potentiodynamic polarization tests. The effect of cold deformation on the microstructure and corrosion behavior of steels was analyzed. In acid solution, both steels exhibited lower corrosion resistance than in chloride solution independently on the steel state (hot-rolled, cold-worked). Cold deformation decreases the corrosion resistance, though this effect is smaller than the effect of chemical composition related to the combined Al + Si addition. All steels showed the evidence of pitting corrosion. The intensive dissolution of Fe and Mn takes place in the acid medium.

  19. Investigation of Electrochemical Charging Behaviors of“Naked” Gold Nanoparticles Ensembles in Aqueous Media

    Institute of Scientific and Technical Information of China (English)

    程文龙; 韩晓军; 彭章泉; 董绍俊; 汪尔康

    2002-01-01

    Gold nanoparticles were imnoobilized onto the electrode surface by simple self-assembly technique.Interestingly,the ensembles of these nanoparticles exhibit quantized charging behaviors in aqueous solution.Possible mechanism for such behaviors was proposed.

  20. Investigation of Electrochemical Charging Behaviors of "Naked" Gold Nanoparticles Ensembles in Aqueous Media

    Institute of Scientific and Technical Information of China (English)

    CHENG,Wen-Long(程文龙); HAN,Xiao-Jun(韩晓军); PENG,Zhang-Quan(彭章泉); DOGN,Shao-Jun(董绍俊); WANG,Er-Kang(汪尔康)

    2002-01-01

    Gold nanoparticles were immobilized onto the electrode surface by simple self-assembly technique. Interestingly, the ensmbles of these nanoparticles exhibit quantized charging behaviors in aqueous solution. Possible mechanism for such behaviors was proposed.

  1. Corrosion Behaviour of Zirconium Alloys in High Temperature Aqueous Environment By Electrochemical Impedance Spectroscopy

    OpenAIRE

    Wang, Peng

    2011-01-01

    The corrosion behaviour of zirconium based alloys has been primarily investigated by electrochemical impedance spectroscopy (EIS). In-situ autoclave EIS experiments were performed in simulated primary coolant conditions in order to study the high temperature water corrosion of zirconium alloys in PWRs. In-situ impedance response of the corroding material was recorded throughout first kinetic transition.A physical model of the zirconium oxide was proposed in accordance with the microstructural...

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

    International Nuclear Information System (INIS)

    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)

  3. Corrosion rate of copper in aqueous lithium bromide concentrated solutions at room temperature by immersion tests

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Portero, M.J.; Garcia-Anton, J.; Guinon-Segura, J.L.; Perez-Herranz, V. [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, P.O. Box 22012, E-46071 Valencia (Spain)

    2004-07-01

    Concentrated solutions of lithium bromide (LiBr) are widely used in absorption refrigeration and heating systems. However, LiBr solutions can cause serious corrosion problems in structural materials (copper, steels, and other metals) in an absorption plant. The aim of the present work was the study of the corrosion rate of copper in 400 and 700 g/L (4.61 and 8.06 M) LiBr solutions pre-nitrogenous or pre-oxygenated at room temperature by immersion tests. The corroded copper concentration was determined with two techniques: weight-loss method and polarographic method. The corrosion curves of copper in LiBr solutions at room temperature as a function of the exposure time showed a similar tendency, and were fitted to a power function such as: C = kt{sup b}, where C was the corroded copper quantity per unit area (mg/cm{sup 2}), t was the exposure time (h), k was the corrosion coefficient, and b was the time exponent. From the corrosion coefficient values (k) it was deduced that the corrosion rate of copper in LiBr solutions at room temperature followed the order: 400 g/L (bubble of O{sub 2}) > 400 g/L (bubble of N{sub 2}) > 700 g/L (bubble of O{sub 2}) > 700 g/L (bubble of N{sub 2}). (authors)

  4. Corrosion Behavior of Medium Carbon Steel in Simulated Concentrated Yucca Mountain Waters

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, A; Chandra, D; Rebak, R B

    2004-04-09

    Medium carbon steel (MCS) is the candidate material for rock bolts to reinforce the borehole liners and emplacement drifts of the proposed Yucca Mountain (YM) high-level nuclear waste repository. Corrosion performance of this structural steel -AISI 1040- was investigated by techniques such as linear polarization, electrochemical impedance spectroscopy (EIS), and laboratory immersion tests in lab simulated concentrated YM ground waters. Corrosion rates of the steel were determined for the temperatures in the range from 25 C to 85 C, for the ionic concentrations of 1 time (1x), 10 times (10x), and hundred times (100x) ground waters. The MCS corroded uniformly at the penetration rates of 35-200 {micro}m/year in the de-aerated YM waters, and 200-1000 {micro}m/year in the aerated waters. Increasing temperatures in the de-aerated waters increased the corrosion rates of the steel. However, increasing ionic concentrations influenced the corrosion rates only slightly. In the aerated 1x and 10x waters, increasing temperatures increased the rates of MCS significantly. Inhibitive precipitates, which formed in the aerated 100x waters at higher temperatures (65 C and up) decreased the corrosion rates to the values that obtained for the de-aerated YM aqueous environments. The steel suffered pitting corrosion in the both de-aerated and aerated hot YM environments after anodic polarization.

  5. Effect of temperature on the corrosion behavior of mild steel upon exposure to palm biodiesel

    International Nuclear Information System (INIS)

    Recently biodiesel, as an alternative fuel is getting more significance to replace diesel fuel completely or partially. However, corrosion of automotive materials in biodiesel is a major concern as this can reduce engine life. This study aims to investigate the corrosion behavior of mild steel at three different temperatures such as room temperature, 50 and 80 oC. Static immersion tests in B0 (diesel), B50 (50% biodiesel in diesel), B100 (biodiesel) were carried out for 1200 h. At the end of the tests, corrosion characteristic was investigated by weight loss measurements and changes of the exposed metal surface. Fuels were analyzed by using TAN analyzer and Fourier transform infrared spectroscopy (FTIR) in order to investigate the change in acidity and oxidation of fuel respectively upon exposure. Surface morphology was examined by optical microscope and scanning electron microscope equipped with energy dispersive spectroscopy. Corrosion products were detected by X-ray diffraction (XRD). Results showed that the corrosion of mild steel increases with increase of temperature. Upon exposure of biodiesel to mild steel at high temperature, the water content and oxidation products are increased. -- Highlights: → Corrosion of mild steel in both diesel and biodiesel increases with increase of temperature. → Degradation of fuel properties also increases with increase of temperature. → Corrosion attacks for metal surfaces are comparatively more in biodiesel than that in diesel fuel. → The constituents of corrosion products are composed of iron carbide and iron oxides.

  6. Corrosion behavior of plasma sprayed ceramic and metallic coatings on carbon steel in simulated seawater

    International Nuclear Information System (INIS)

    Highlights: • Plasma sprayed Ni60 coating can provide corrosion protect for the substrate. • Depositing ceramic coatings on metallic coating can improve the corrosion resistance. • The corrosion resistance of Al2O3 coating was better than that of ZrO2 coating. • The porosity had direct effect on the corrosion rate of the plasma sprayed coatings. • The top layer and the bond layer were treated as one coating in the EIS tests. - Abstract: Al2O3, ZrO2 and Ni60 coatings were produced on carbon steels by plasma spray. Ni60 was used as the bond coat in all the cases. The microstructure of these coatings was analyzed by scanning electron microscopy (SEM). The corrosion behavior of the plasma spray coated samples as well as uncoated samples was evaluated by open circuit potential (OCP) measurements, potentiodynamic polarization tests, and electrochemical impedance spectroscopy (EIS) in simulated seawater. The results showed that Ni60 coating protected carbon steels against the corrosion and plasma spraying ceramic powders on metallic coating improved the corrosion resistance of the coatings further. The corrosion resistance of the Al2O3 coating was superior to that of the ZrO2 coating due to the relatively few defects in Al2O3 coating

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

    International Nuclear Information System (INIS)

    The corrosion behavior of high-purity (99.99%) Fe-Cr-Ni alloys was investigated in 13 N nitric acid with/without Ce4+ 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)

  8. Corrosion Behavior of Carbon Steels in CCTS Environment

    Directory of Open Access Journals (Sweden)

    M. Cabrini

    2016-01-01

    Full Text Available The paper reports the results of an experimental work on the effect of steel microstructures on morphology and protectiveness of the corrosion scale formed in water saturated by supercritical CO2. Two HSLA steels were tested. The microstructures were modified by means of different heat treatments. Weight loss was measured after exposure at CO2 partial pressure of 80 bar and 60°C temperature. The morphology of the scale was analyzed by means of scanning electron microscope (SEM energy-dispersive X-ray spectroscopy (EDX. Cathodic potentiodynamic tests were carried out on precorroded specimens for evaluating the effect of preformed scales on cathodic polarization curves in CO2 saturated sulphuric acid solution at pH 3, which is the value estimated for water saturated by supercritical CO2. The results are discussed in order to evaluate the effect of iron carbide network on scale growth and corrosion rate. Weight loss tests evidenced average corrosion rate values in the range 1–2.5 mm/y after 150-hour exposure. The presence of thick siderite scale significantly reduces the corrosion rate of carbon steel. A slight decrease of the corrosion rate was observed as the scale thickness increases and moving from martensite to microstructures containing carbides.

  9. Microstructure, Cyclic Deformation and Corrosion Behavior of Laser Welded NiTi Shape Memory Wires

    Science.gov (United States)

    Mirshekari, G. R.; Kermanpur, A.; Saatchi, A.; Sadrnezhaad, S. K.; Soleymani, A. P.

    2015-09-01

    The present paper reports the effects of Nd:YAG laser welding on the microstructure, phase transformation, cyclic deformation behavior, and corrosion resistance of Ti-55 wt.% Ni wire. The results showed that the laser welding altered the microstructure of the weld metal which mainly composed of columnar dendrites grown epitaxially from the fusion line. DSC results indicated that the onset of the transformation temperatures of the weld metal differed from that of the base metal. Cyclic stress-strain behavior of laser-welded NiTi wire was comparable to the as-received material; while a little reduction in the pseudo-elastic property was noted. The weld metal exhibited higher corrosion potential, lower corrosion current density, higher breakdown potential and wider passive region than the base metal. The weld metal was therefore more resistant to corrosion than the base metal.

  10. Effect of Surface Stress Mitigation on the Corrosion Behavior of Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    Fix, D V; Yilmaz, A; Wong, L L; Estill, J C; Rebak, R B

    2004-11-10

    When metallic plates are welded, for example using the Gas Tungsten Arc Welding (GTAW) process, residual tensile stresses may develop in the vicinity of the weld seam. Processes such as Low Plasticity Burnishing (LPB) and Laser Shock Peening (LSP) could be applied locally to eliminate the residual stresses produced by welding. In this study, Alloy 22 (N06022) plates were welded and then the above-mentioned surface treatments were applied to eliminate the residual tensile stresses. The aim of the current study was to comparatively test the corrosion behavior of as-welded (ASW) plates with the corrosion behavior of plates with stress mitigated surfaces. Immersion and electrochemical tests were performed. Results from both general and localized corrosion tests show that the corrosion resistance of the mitigated plates was not affected by the surface treatments applied.

  11. Effect of fluorides and chlorides upon corrosion behavior of alloy C-22

    International Nuclear Information System (INIS)

    Alloy C-22 is one of the candidates to fabricate the external wall of the high level nuclear waste containers. These packages are designed to maintain isolation of the waste for a minimum of 10,000 years. During this period they must resist atmospheric corrosion. Electrochemical techniques such as cyclic potentiodynamic polarization, electrochemical impedance spectroscopy and variation of corrosion potential in time and non-electrochemical techniques such as X-ray fluorescence (XRF) and microscopy were applied to determine the effect of fluorides and chlorides upon general and localized corrosion of different microstructures of alloy C-22. The corrosion rates obtained were about 0.1 μm/year. Crevice corrosion was detected only in those solutions where chlorides ions were present. Fluoride ions affected the passivity and trans passivity behavior of the alloy. They produced higher current densities than chlorides in both ranges. There were no differences in corrosion behavior of the different microstructures. Mixtures of chlorides and fluorides seem to be more detrimental than the separated ions regarding to localized corrosion and trans passivity. (author)

  12. Relationship between Heat Treatment and Corrosion Behavior of Mg-15Y Alloy

    Institute of Scientific and Technical Information of China (English)

    XU Hong; DENG Xia; ZHANG Xin; ZHANG Kui; LIU Yanpeng; LI Shaohua

    2015-01-01

    The corrosion behaviors of a basic type of RE-containing magnesium alloy Mg-15Y processed by different heat treatment methods were studied in 3.5% NaCl solution at room temperature. The amount of Mg24Y5phase decreased with the extending of homogenization treatment. The time for achieving dissolving equilibrium of homogenization treatment at 525, 535, and 545℃ was 24, 20, and 8 h, respectively. The corrosion behavior of Mg-15Y alloy was studied using immersion, hydrogen evolution and electrochemical tests. The experimental results revealed that the heat treatment improved the corrosion resistance, and the corrosion resistance became better with increasing the heat treatment time. The corrosion mode of the alloy after heat treatment was microgalvanic corrosion consisting of the cathodic Mg24Y5 phase and anodic α-Mg matrix, and Mg-15Y exhibited favorable uniform corrosion mode in NaCl solution. The volume and increasing tendency of the homogenization treatment samples were both more than those of the as-cast sample.

  13. 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.

  14. Stress corrosion cracks behavior and its protective technique under landfill disposal environment of the radioactive wastes

    International Nuclear Information System (INIS)

    The effects of water and addition of chemicals on the stress corrosion cracks of granite from Oshima, Ehime Prefecture, were studied. The cracking behavior was investigated by in situ observation by SEM. The stress corrosion cracks were affected by anisotropy and it grew quickly in direction of the weakest linkage. The stress corrosion cracking index and cracking velocity under the constant load were changed significantly by ζ potential. It was proved by SEM that the main mode of cracking growth was the intergranular fracture under the dry condition. (S.Y.)

  15. Corrosion behavior of sintered zinc-aluminum coating in NaCl solution

    Institute of Scientific and Technical Information of China (English)

    陈玲; 李宁; 周德瑞

    2002-01-01

    Sintered zinc-aluminum coating (SZAC) was prepared using zinc flakes, aluminum flakes and CrO3 as main raw materials. The corrosion behavior of SZAC in 3.5%NaCl solution was studied by means of SEM, EDS, EIS and so on. Results indicate that aluminum corroded in advance of zinc to produce speculate or spherical substances, which attaches to SZAC and adds mass to it. Corrosion production passivates metal powders in SZAC, causes Ecorr of SZAC to increase gradually, and causes the arising of the third time constant in EIS, which corresponds to the insulation of corrosion production.

  16. Corrosion potential behavior of noble metal-modified alloys in high temperature water

    International Nuclear Information System (INIS)

    Intergranular stress corrosion cracking (IGSCC) of sensitized stainless steel (SS) components in boiling water reactors (BWRs) is known to be a major concern. There the effect of Pd or Pt additions to various alloys on the corrosion potential behavior was investigated in 288 C water containing various amounts of oxygen, hydrogen, and hydrogen peroxide. The data showed that the noble-metal alloying additions to engineering materials improved the catalytic efficiency for the recombination of oxygen and hydrogen on the surface and thereby lowered the corrosion potential for IGSCC protection when the molar ratio of hydrogen to oxygen in water is greater than about 2

  17. Effect of lanthanum addition on microstructure and corrosion behavior of AI-Sn-Bi anodes

    Institute of Scientific and Technical Information of China (English)

    HOU Delong; LI Defu; HAN Li; JI Lianqin

    2011-01-01

    Novel Al-Sn-Bi anodes with and without lanthanum (La) were prepared. To evaluate the corrosion properties of the anodes, constant current and dynamic loop tests were carried out to determine its efficiency and corrosion rote. Optical microscopy (OM), transmission electron microscopy (TEM) and energy spectrum analysis techniques were used to examine and analyze microstructure and corrosion behavior of the specimens. The result showed that the Al-Sn-Bi anodes with La additions revealed higher current efficiency and anticorrosion in artificial environment. Segregation phase of anodes with La additions got more homogenous than that without La additions. Its grains were fined and the amount of segregation Fe-phase was reduced.

  18. Corrosion and Runoff Behavior of Carbon Steel in Simulated Acid Rain

    Institute of Scientific and Technical Information of China (English)

    Baigang AN; Xueyuan ZHANG; Enhou HAN; Honxi LI

    2004-01-01

    Under the condition of simulated rain precipitation in the laboratory, with ElS and SEM observation, the effects of pH value of simulated rain on corrosion and runoff behavior of carbon steel A3 were studied. The corrosion rate of A3 steel increased and runoff action of rain precipitation on A3 steel surface was intensified with decreasing pH value, of simulated rainwater.The runoff and corrosion traces were formed along the flowing direction of rainwater, which appeared more apparently with decreasing pH value.

  19. 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.

  20. Corrosion Behavior of Commercial Aluminum Alloy Processed by Equal Channel Angular Pressing

    OpenAIRE

    Atef Korchef; Abdelkrim Kahoul

    2013-01-01

    A commercial aluminum alloy was subjected to severe plastic deformation through equal channel angular pressing (ECAP). The alloy contains a low volume fraction of α-AlFeSi located essentially at the grain boundaries. The corrosion behavior of the ECAP’ed alloy was investigated in NaCl solution using potentiodynamic polarization and immersion tests. The effects of scan rate and NaCl concentration on the alloy susceptibility to corrosion were also studied. The results obtained were compared wit...

  1. Corrosion-electrochemical behavior of diffusionally chromized carbon steels in aggressive environments

    International Nuclear Information System (INIS)

    One generalized the experimental data of many year investigations into corrosion-electrochemical behavior of diffusionally chromized carbon steels (steel 45) depending on diffusion saturation process factors and on composition of saturating powder mixture. One formulated compositions of saturating powder enabling to improve essentially corrosion resistance of treated carbon steels in the aggressive environments. Resistance is improved due to introduction of calcium hydride into saturating mixture

  2. Corrosion Behavior of Ti-6Al-4V Alloy in Different Media

    OpenAIRE

    Slafa I. Ibrahim; Majid H. Abdulmageed

    2010-01-01

    In this work the corrosion behavior of Ti-6Al-4V alloy was studied by using galvanostatic measurements at room temperature in different media which includ sodium chloride (food salt), sodium tartrate (presence in jellies, margarine, and sausage casings,etc.), sodium oxalate (presence in fruits, vegetables,etc.), acetic acid (presence in vinegar), phosphoric acid (presence in drink), sodium carbonate (presence in 7up drink,etc.), and sodium hydroxide in order to compare. Corrosion parameters w...

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

    OpenAIRE

    Gvozdenović Milica M.; Grgur Branimir N.; Kačarević-Popović Zorica M.; Mišković-Stanković Vesna B.

    2005-01-01

    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 th...

  4. Corrosion Inhibition and Adsorption Behavior of Clove Oil on Iron in Acidic Medium

    OpenAIRE

    Saxena, Archana; Sharma, Anurag; Saxena, Deepti; Jain, Praveen

    2012-01-01

    Corrosion behavior of iron in hydrochloric acid solution was studied using weight loss as well Scanning electron microscopy study without and with clove oil. The percentage inhibition efficiency increases with increasing clove oil concentration. All the data revel that the oil acts as an excellent inhibitor for the corrosion of iron in HCl solution. Thermodynamic, kinetic parameters and equilibrium constant for adsorption process were calculated from the experimental data. The adsorption of c...

  5. Incipient corrosion behavior of Haynes 230 under a controlled reducing atmosphere at high temperatures

    Science.gov (United States)

    Tung, Hsiao-Ming; Stubbins, James F.

    2012-08-01

    In situ thermogravimetry analysis (TGA) was used to investigate the incipient corrosion behavior of alloy 230 exposed under a reducing environment in a temperature range of 850-1000 °C. Both oxidation and loss of alloying elements of alloy 230 were observed to occur concurrently in these conditions. The surface oxide which formed on the substrate does not appear to be as effective in providing a protective layer during the incipient corrosion period.

  6. Lead-bismuth eutectic corrosion behaviors of ferritic/martensitic steels in low oxygen concentration environment

    OpenAIRE

    Liu, Jian; Shi, Quanqiang; Luan, He; Yan, Wei; Sha, Wei; Wang, Wei; Shan, Yiyin; Yang, Ke

    2015-01-01

    In order to investigate the compatibility of candidate structural materials with liquid metals, two kinds of ferritic/martensitic steels were chosen to contact with lead–bismuth eutectic in sealed quartz–glass tubes. The corrosion exposures were for 500 and 3000 h. Results showed that the oxidation layer and carbide dissolution layer on the two steels grew with contact time under oxygen unsaturated condition. Short-term corrosion behavior of a newly developed steel showed better lead–bismuth ...

  7. Corrosion behavior of Co-Sm based magnetic media

    International Nuclear Information System (INIS)

    In this article the long term stability of Co-Sm thin films, both with no overcoat and covered with silicon nitride layers of varying thickness, has been investigated by means of accelerated corrosion tests in vacuum, air, and in a humidity chamber. Bare Co-Sm films exhibit an accelerated decrease in magnetization with respect to reference Co-Pt films, dependent in part on the effective surface area of the magnetic film. X-ray photoelectron spectroscopy depth profiling and corrosion tests demonstrate that silicon nitride layers of about 8 nm should provide adequate protection against degradation of the magnetic properties of Co-Sm thin films

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

    International Nuclear Information System (INIS)

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

  9. Stability and corrosion resistance of superhydrophobic surface on oxidized aluminum in NaCl aqueous solution

    Science.gov (United States)

    Lv, Damei; Ou, Junfei; Xue, Mingshan; Wang, Fajun

    2015-04-01

    Superhydrophobic surface (SHS) was fabricated on aluminum via surface roughening by NaClO and surface passivation by hexadecyltrimethoxysilane. The long-term durability for storing the sample in air and the chemical stability for contacting the sample with NaCl solution were investigated. The short-term corrosion resistance for immersing the sample in NaCl solution for 1 h was investigated by potentiodynamic polarization, and the long-term corrosion resistance for immersing the sample in NaCl solution for 7 days was investigated by variation analyses on surface wettability, surface morphology, and surface chemistry. All experimental results suggested that the so-obtained SHS possessed good stability and good corrosion resistance under the testing conditions.

  10. Investigation of hexagonal boron nitride as an atomically thin corrosion passivation coating in aqueous solution

    Science.gov (United States)

    Zhang, Jing; Yang, Yingchao; Lou, Jun

    2016-09-01

    Hexagonal boron nitride (h-BN) atomic layers were utilized as a passivation coating in this study. A large-area continuous h-BN thin film was grown on nickel foil using a chemical vapor deposition method and then transferred onto sputtered copper as a corrosion passivation coating. The corrosion passivation performance in a Na2SO4 solution of bare and coated copper was investigated by electrochemical methods including cyclic voltammetry (CV), Tafel polarization and electrochemical impedance spectroscopy (EIS). CV and Tafel analysis indicate that the h-BN coating could effectively suppress the anodic dissolution of copper. The EIS fitting result suggests that defects are the dominant leakage source on h-BN films, and improved anti-corrosion performances could be achieved by further passivating these defects.

  11. 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.

  12. Corrosion behavior of construction materials for intermediate temperature steam electrolysers

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey; Petrushina, Irina; Jensen, Jens Oluf;

    2013-01-01

    resistance and the anodic and cathodic limits were for the first time found for the electrolyte. Nickel, niobium, Inconel®625, Hastelloy®C-276 and Ta-coated stainless steel (AISI 316L) demonstrated high corrosion stability and can be recommended as construction materials for bipolar plates. © (2013) Trans...

  13. Galvanic corrosion behavior of titanium implants coupled to dental alloys.

    Science.gov (United States)

    Cortada, M; Giner, L; Costa, S; Gil, F J; Rodríguez, D; Planell, J A

    2000-05-01

    The corrosion of five materials for implant suprastructures (cast-titanium, machined-titanium, gold alloy, silver-palladium alloy and chromium-nickel alloy), was investigated in vitro, the materials being galvanically coupled to a titanium implant. Various electrochemical parameters E(CORR), i(CORR) Evans diagrams, polarization resistance and Tafel slopes) were analyzed. The microstructure of the different dental materials was observed before and after corrosion processes by optical and electron microscopy. Besides, the metallic ions released in the saliva environment were quantified during the corrosion process by means of inductively coupled plasma-mass spectrometry technique (ICP-MS). The cast and machined titanium had the most passive current density at a given potential and chromium-nickel alloy had the most active critical current density values. The high gold content alloys have excellent resistance corrosion, although this decreases when the gold content is lower in the alloy. The palladium alloy had a low critical current density due to the presence of gallium in this composition but a selective dissolution of copper-rich phases was observed through energy dispersive X-ray analysis. PMID:15348025

  14. Laboratory testing of waste glass aqueous corrosion; effects of experimental parameters

    International Nuclear Information System (INIS)

    A literature survey has been performed to assess the effects of the temperature, glass surface area/leachate volume ratio, leachant composition, leachant flow rate, and glass composition (actual radioactive vs. simulated glass) used in laboratory tests on the measured glass reaction rate. The effects of these parameters must be accounted for in mechanistic models used to project glass durability over long times. Test parameters can also be utilized to highlight particular processes in laboratory tests. Waste glass corrosion results as water diffusion, ion-exchange, and hydrolysis reactions occur simultaneously to devitrify the glass and release soluble glass components into solution. The rates of these processes are interrelated by the affects of the solution chemistry and glass alteration phases on each process, and the dominant (fastest) process may change as the reaction progresses. Transport of components from the release sites into solution may also affect the observed corrosion rate. The reaction temperature will affect the rate of each process, while other parameters will affect the solution chemistry and which processes are observed during the test. The early stages of corrosion will be observed under test conditions which maintain dilute leachates and the later stages will be observed under conditions that generate more concentrated leachate solutions. Typically, water diffusion and ion-exchange reactions dominate the observed glass corrosion in dilute solutions while hydrolysis reactions dominant in more concentrated solutions. Which process(es) controls the long-term glass corrosion is not fully understood, and the long-term corrosion rate may be either transport- or reaction-limited

  15. Long-Term Corrosion Behavior of CVD SiC in PWR-Simulating Water

    International Nuclear Information System (INIS)

    SiC ceramics show an outstanding oxidation resistance and a low hydrogen liberation rate in hot steam compared with the current Zr alloys, which promise larger safety margins under severe accident conditions. Moreover, its high temperature strength and stability under high neutron doses also provide high burn-up capability. In spite of the potential benefits of the SiC composite cladding, there are a lot of technical issues that need to be clarified for the LWR application. Especially, the corrosion resistance in the PWR water is an important parameter to insure the cladding performance under normal operating condition. Generally, SiC ceramics are highly corrosion resistant by forming a protective SiO2 layer in an air atmosphere. Long-term corrosion behavior of CVD SiC was investigated under simulated PWR primary water conditions. The dissolved hydrogen of about 2.7 ppm dramatically reduced the corrosion rate of SiC at 360 .deg. C under 20 MPa. The corrosion weight loss of CVD SiC under the dissolved hydrogen-controlled condition was extremely small compared with the condition without controlling the dissolved hydrogen. The oxide layer on the SiC specimen was readily dissolved and the SiC bare surface was exposed at the initial stage of the corrosion test. After the dissolution of the oxide layer, however, further corrosion occurred in a very sluggish way

  16. Corrosion Behavior of Welded Joints of Al-6Mg Alloy with Trace Scandium Addition

    Institute of Scientific and Technical Information of China (English)

    Wang Yue

    2004-01-01

    Al-6Mg alloy with trace Sc addition was prepared by means of melting-casting.The samples of the welded joints of Al-6Mg alloy with trace Sc addition were made by method of manual argon-arc welding.Neutral salt spray test was carried out by referring to GB/T10125-1997 and GB6384-1986 practice.Exfoliation testing was carried out in accordance with the method of Al-Mg alloy exfoliation corrosion test.The corrosion behaviors of the welded joints of AlMg alloy with high level of Mg and trace Sc addition were studied.The microstructures of the welded joints were observed by using optical microscope and transmission electron microscope.The corrosion resistance mechanism of the alloy was also involved.This work intended to determine if the welded joints of Al-6Mgalloy with trace Sc addition can have excellent corrosion resistance, when their strength are clearly improved.The results show that trace content of Sc refines the grains of alloys effectively, raises remarkably the corrosion resistance of the welded joints of Al-6Mg alloy with trace Sc addition.The corrosion resistance mechanisms are that there is free of continuous grain boundary precipitation or network which could be susceptible to corrosion in the microstructure of welded joints.

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

    Directory of Open Access Journals (Sweden)

    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.

  18. Dependence of the corrosion behavior of aluminum alloy 7075 on the thin electrolyte layers

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, H.R. [State Key Laboratory of Environmental Adaption for Industrial Products, China National Electric Apparatus Research Institute, Guangzhou 510663 (China); Corrosion and Protection Center, University of Science and Technology Beijing, Beijing 100083 (China); Li, X.G. [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing 100083 (China)], E-mail: lixiaogang99@263.net; Ma, J. [State Key Laboratory of Environmental Adaption for Industrial Products, China National Electric Apparatus Research Institute, Guangzhou 510663 (China); Dong, C.F. [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing 100083 (China); Huang, Y.Z. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2009-05-15

    The corrosion behavior of aluminum alloy 7075-T6 dependent of the thin electrolyte layers in 1 M sodium sulfate solution has been investigated using cathodic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The oxygen reduction current is measured to be maximum at -1.1 V by cathodic polarization test when the thickness of the electrolyte layer is 110 {mu}m. The EIS results show that the corrosion rate increases with the increase of the immersing time independent of thickness of the electrolyte layer although 110 {mu}m thick electrolyte layer produces the largest corrosion rate over the immersing time between 0 h and 96 h. However, with the longer immersing time, corrosion rate of the sample in bulk solution becomes higher. This result can be explained that the diffusion of the corrosion product and the metal ions from the electrode in the case of the thicker layer is easier. SEM morphologies reveal that corrosion products on the surface of the samples are distributed unhomogenously, with their amount near edges being more than the center area. In addition, XPS analysis demonstrates that corrosion products are mainly composed of Al(OH){sub 3} and Al{sub 2}(SO{sub 4}){sub 3}.

  19. Stress corrosion cracking behavior of Ni28Mo-alloys: Recent research data

    International Nuclear Information System (INIS)

    Nickel-molybdenum alloys of the type Ni28Mo/alloy B-2 may fail in service due to stress corrosion cracking in components, where a high heat input during manufacturing or repair such as repeated welding operations may have occurred. Therefore, various tests in solution annealed and aged condition on different alloy compositions have been done with respect to stress corrosion resistance, uniform and intergranular corrosion and time-temperature-sensitization behavior. Stress corrosion sensitivity of the Ni28Mo materials in the aged condition is dependent on the alloys degree of ordering which is delayed by increasing alloying additions of iron and chromium. Therefore, in order to improve the stress corrosion resistance these alloying additions have to be increased beyond the limits being set for the current alloy B-2 grade. Consequently, a new Ni28Mo alloy type, alloy B-4 is proposed being alloyed with 2--5 wt % Fe and 0.5--1.5 wt % Cr. This new Ni28Mo alloy exhibits a considerably improved resistance to stress corrosion cracking which is achieved without impairing the resistance to overall uniform and to intergranular corrosion. Resistance to sensitization is also improved

  20. Corrosion Behavior of Ti-6Al-4V Alloy in Different Media

    Directory of Open Access Journals (Sweden)

    Slafa I. Ibrahim

    2010-01-01

    Full Text Available In this work the corrosion behavior of Ti-6Al-4V alloy was studied by using galvanostatic measurements at room temperature in different media which includ sodium chloride (food salt, sodium tartrate (presence in jellies, margarine, and sausage casings,etc., sodium oxalate (presence in fruits, vegetables,etc., acetic acid (presence in vinegar, phosphoric acid (presence in drink, sodium carbonate (presence in 7up drink,etc., and sodium hydroxide in order to compare. Corrosion parameters were interpreted in these media which involve corrosion potential( Ecorr and corrosion current density (icorr, since the results of (Ecorr indicate that Oxalate ions are more corrosive than other materials while the results of (icorr indicate that NaCl is more corrosive than other materials. Cathodic and Anodic Tafel slopes that were used to calculate the polarization resistance (Rp to know which materials effect on Ti-6Al-4V alloy uses in dental materials and the results of (Rp were: Na2CO3 >Oxalate >H3PO4 >CH3COOH >NaOH >Tartrate >NaCl. The change in free energy (∆G and rate of corrosion in (mpy were calculated, and the results of rate indicate that increasing in the following sequences: NaCl>Tartrate >NaOH >Oxalate> CH3COOH> H3PO4> Na2CO3.

  1. 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.

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

    International Nuclear Information System (INIS)

    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

  3. Correlation between General Corrosion Behavior and Eddy Current Noise of Alloy 690 Steam Generator Tube

    International Nuclear Information System (INIS)

    Nickel and its oxides are released from the surface of steam generator tubes into the primary water. Released nickel and cobalt is activated to Co-58 and Co-60 in the reactor core by a neutron flux, respectively. These activated corrosion products are the main source of high radiation fields and occupational radiation exposure. In addition, some of the corrosion products redeposit on the fuel cladding, hinder the heat transfer, increase the corrosion rate of the fuel cladding, and finally induce an axial offset anomaly. This phenomenon can decrease core shutdown margin, and thus lead to a down-rating of a plant. Recently, many researchers have reported that the surface states of Alloy 690 tubes affect the corrosion product formation and its release in simulated primary water environments. Meanwhile, the surface states of steam generator tubes affect the noise level of eddy current testing. Noise signals arising from the tubes degrade the probability of detection and sizing accuracy of the defects. The corrosion behavior was closely correlated to the tube noise measured using a rotating probe, while it was not related to the noise measured using a bobbin probe. It is suggested that the tube noise value measured using a rotating pancake coil probe can be a decisive measure to estimate the corrosion behavior of tubing

  4. Stress corrosion cracking behavior of friction stir welded Al 6061-T651

    International Nuclear Information System (INIS)

    In the present study, corrosion behavior of Friction Stir Welded (FSWed) Al 6061-T651 with varying welding parameters, including rotating and welding speeds, were examined. The 4 mm thick Al 6061-T651 alloy plates were friction stir welded. The resistance to corrosion was slightly improved, or at least did not decrease, for FSWed Al 6061-T651 alloy in 3.5% NaCl solution compared to the parent material. The effect of different welding conditions on the corrosion resistance was minimal. The micrographic and fractographic observations strongly suggested that the change in corrosion behavior of FSWed Al 6061-T651 was largely related to the clustering of coarse Mg2Si precipitates, due to the whirling and casting action by severe plastic flow in the weld zone. Low welding speed and/or high rotating speed tended to encourage the plastic flow per unit unit time and consequently the clustering of coarse precipitates. The resistance to SCC in 3.5% NaCl solution was considerably higher for the FSWed Al 6061-T651 compared to that of the PM counterpart. The improved SCC resistance for the FSWed specimen was due to the fast that the stress corrosion cracks were enhanced at the boundary between the DXZ and the HAZ due to the greatest galvanic corrosion potential difference between the two phases, while the tensile fracture occurred at the other area where the strength level was the lowest

  5. Corrosion Behavior of Alloy 22 in Oxalic Acid and Sodium Chloride Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Day, S D; Whalen, M T; King, K J; Hust, G A; Wong, L L; Estill, J C; Rebak, R B

    2003-06-24

    Nickel based Alloy 22 (NO6022) is extensively used in aggressive industrial applications, especially due to its resistance to localized corrosion and stress corrosion cracking in high chloride environments. The purpose of this work was to characterize the anodic behavior of Alloy 22 in oxalic acid solution and to compare its behavior to sodium chloride (NaCl) solutions. Standard electrochemical tests such as polarization resistance and cyclic polarization were used. Results show that the corrosion rate of Alloy 22 in oxalic acid solutions increased rapidly as the temperature and the acid concentration increased. Extrapolation studies show that even at a concentration of 10{sup -4}M oxalic acid, the corrosion rate of Alloy 22 would be higher in oxalic acid than in 1 M NaCl solution. Alloy 22 was not susceptible to localized corrosion in oxalic acid solutions. Cyclic polarization tests in 1 M NaCl showed that Alloy 22 was susceptible to crevice corrosion at 90 C but was not susceptible at 60 C.

  6. Correlation between General Corrosion Behavior and Eddy Current Noise of Alloy 690 Steam Generator Tube

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Do Haeng; Choi, Myung Sik; Lee, Deok Hyun; Shim, Hee-Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Nickel and its oxides are released from the surface of steam generator tubes into the primary water. Released nickel and cobalt is activated to Co-58 and Co-60 in the reactor core by a neutron flux, respectively. These activated corrosion products are the main source of high radiation fields and occupational radiation exposure. In addition, some of the corrosion products redeposit on the fuel cladding, hinder the heat transfer, increase the corrosion rate of the fuel cladding, and finally induce an axial offset anomaly. This phenomenon can decrease core shutdown margin, and thus lead to a down-rating of a plant. Recently, many researchers have reported that the surface states of Alloy 690 tubes affect the corrosion product formation and its release in simulated primary water environments. Meanwhile, the surface states of steam generator tubes affect the noise level of eddy current testing. Noise signals arising from the tubes degrade the probability of detection and sizing accuracy of the defects. The corrosion behavior was closely correlated to the tube noise measured using a rotating probe, while it was not related to the noise measured using a bobbin probe. It is suggested that the tube noise value measured using a rotating pancake coil probe can be a decisive measure to estimate the corrosion behavior of tubing.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. 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.

  9. Corrosion Behavior of Austenitic and Duplex Stainless Steels in Lithium Bromide

    Directory of Open Access Journals (Sweden)

    Ayo Samuel AFOLABI

    2009-07-01

    Full Text Available The corrosion behavior of austenitic and duplex stainless steels in various concentrations of lithium, bromide solution was investigated by using the conventional weight loss measurement method. The results obtained show that corrosion of these steels occurred due to the aggressive bromide ion in the medium. Duplex stainless steel shows a greater resistance to corrosion than austenitic stainless steel in the medium. This was attributed to equal volume proportion of ferrite and austenite in the structure of duplex stainless steel coupled with higher content of chromium in its composition. Both steels produced electrochemical noise at increased concentrations of lithium bromide due to continuous film breakdown and repair caused by reduction in medium concentration by the alkaline corrosion product while surface passivity observed in duplex stainless steel is attributed to film stability on this steel.

  10. Study on Grain Boundary Structure and Corrosion Behavior of Copper Alloys

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The grain boundary structure of Cu alloy was observed and the characteristic of the boundaries was studied,including 70∶30 cupronickel and 7 0∶30 brass. The results show that in the case of the 70∶30 cupronickel thin platelets with nickel and iron e nrichment in it precipitate intergranular so that the alloy was sensitive to sea water corrosion. In the case of 70∶30 brass the situation of grain boundary seg regation of different inclusions made the corrosion resistance of the alloy even worse. All of those were discovered through the corrosion behavior of the two d iff erent copper alloys served in various environments. The experimental methods use d here were, scanning electron microscopy(SEM), transmission electron microscopy(T EM) and energy dispersive of X ray(EDX). The intergranular corrosion morphologie s of those copper alloys served in engineering or exposed to seaw ater for a long term were given.

  11. Initial Corrosion Behavior and Mechanism of PCB-HASL in Typical Outdoor Environments in China

    Science.gov (United States)

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

    2015-11-01

    A long-term (1, 3, and 6 months) outdoor exposure test was performed for lead-free hot air solder leveling printed circuit boards (PCB-HASL) in typical environments in China and the corrosion behavior and mechanism of outdoor PCB-HASL were investigated. In a dry environment PCB-HASL corroded slightly, because of the protective effect of surface oxide films. Corrosion spread from places where dust particles were deposited or mold spores were adsorbed. Under the combined effects of humidity and contamination, large amounts of granular corrosion products with a loose structure were generated, greatly reducing the protective effect of the Sn layer. Furthermore, protection of the edges of the plates was poor, and corrosion products from these regions migrated rapidly on the FR-4 board. When a 12 V electrical bias was applied, Sn and Cu migrated simultaneously. In the electrochemical migration process the effect of humidity was much more critical than that of contamination.

  12. Corrosion Behavior of Zirconium Treated Mild Steel with and Without Organic Coating: a Comparative Study

    Science.gov (United States)

    Ghanbari, Alireza; Attar, Mohammadreza Mohammadzade

    2014-10-01

    In this study, the anti-corrosion performance of phosphated and zirconium treated mild steel (ZTMS) with and without organic coating was evaluated using AC and DC electrochemical techniques. The topography and morphology of the zirconium treated samples were studied using atomic force microscopy (AFM) and field emission scanning electron microscope (FE-SEM) respectively. The results revealed that the anti-corrosion performance of the phosphate layer was superior to the zirconium conversion layer without an organic coating due to very low thickness and porous nature of the ZTMS. Additionally, the corrosion behavior of the organic coated substrates was substantially different. It was found that the corrosion protection performance of the phosphate steel and ZTMS with an organic coating is in the same order.

  13. Corrosion behavior of a high-chromium duplex stainless steel with minor additions of ruthenium in sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Potgieter, J.H. [Pretoria Portland Cement, Johannesburg (South Africa). Technical Services Dept.; Brookes, H.C. [Univ. of Natal, Durban (South Africa). Dept. of Chemistry

    1995-04-01

    The influence of small ruthenium additions on the corrosion behavior of high-chromium duplex stainless steels (DSS) was studied. Ruthenium additions ({le} 0.28%) increased the corrosion resistance of the base alloy by simultaneously improving hydrogen evolution efficiency and inhibiting anodic dissolution. The corrosion behavior of the high-chromium DSS with small ruthenium additions differed somewhat from behavior of similar duplex alloys of the 22%-Cr type. The lowering of hydrogen overpotential, which promotes an elevated corrosion potential leading to passivity, was much more significant in the 29%-Cr duplex alloys than in the 22%-Cr types.

  14. The Corrosion Behavior of Carburized Aluminum Using DC Plasma

    Directory of Open Access Journals (Sweden)

    Somayeh Pirizadhejrandoost

    2012-01-01

    Full Text Available Because of the outstanding properties of aluminum, it is widely used in today's advanced technological world. However, its insufficient wear resistance limits its use for commercial and industrial applications. In this study, we performed DC diode plasma carburizing of aluminum in the gas composition of CH4–H2 (20–80% and at a temperature of about 350°C for 4 and 8 hours. The corrosion properties of the untreated and plasma-carburized samples were evaluated using anodic polarization tests in 3 N HCl solution according to ASTM: G5-94. The metallurgical characteristics were then investigated using XRD and SEM. The results showed that the carburizing process improves the corrosion resistance of treated specimens at low temperature.

  15. [Corrosion behavior of dental alloys coated with titanium niobium oxinitride].

    Science.gov (United States)

    Thull, R

    1991-11-01

    Dental alloys coated with (Ti,Nb)ON using the ion are PVD technique exhibit galvanic corrosion current densities of considerably less than Jg = 1 microA/cm2. These measurements were taken on plane surfaces. The results show no signs of local corrosion, which might impair the long-term intraoral stability of dental constructions or the health of the patients. Irrespective of the dental alloys used, the coatings exhibit pores extending down to the alloy. The alloy thus wetted on the one hand, and the coated areas on the other, act as galvanic elements with high source resistances and very low short circuit currents. It may therefore be concluded that the coating will effectively reduce allergic reactions to the components of the dental alloys. PMID:1817869

  16. Corrosion Behavior of Carbon Steels in CCTS Environment

    OpenAIRE

    Cabrini, M; S. Lorenzi; T. Pastore

    2016-01-01

    The paper reports the results of an experimental work on the effect of steel microstructures on morphology and protectiveness of the corrosion scale formed in water saturated by supercritical CO2. Two HSLA steels were tested. The microstructures were modified by means of different heat treatments. Weight loss was measured after exposure at CO2 partial pressure of 80 bar and 60°C temperature. The morphology of the scale was analyzed by means of scanning electron microscope (SEM) energy-dispers...

  17. Initial corrosion behavior of AZ91 magnesium alloy in simulating acid rain under wet-dry cyclic condition

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Corrosion behavior of AZ91 magnesium alloy in simulating acid rain under wet-dry cyclic condition was investigated.The results show that corrosion potential shifts positively and the corrosion current density decreases at low wet-dry cyclic time.Further increase of the cyclic time results in the negative movement of corrosion potential and the increase of current density.SEM observation indicates that corrosion Occurs only in αphase,βphase is inert in corrosive medium,and the corrosion of AZ91 magnesium appears in uniform characteristic.XPS analysis suggests that the corrosion product is mainly composed of oxide and hydroxide of magnesium and aluminum,and a small amount of sulfate is also contained in the film.

  18. Dependence of Corrosion Behavior of SiC Ceramics on PWR Water Chemistry

    International Nuclear Information System (INIS)

    There have also been efforts on applying the SiCf/SiC composites to the light water reactor (LWR) fuel cladding and guide tubes as well as channel boxes for fuel assembly of the boiling water reactor (BWR). In spite of potential benefits of the SiC composite cladding, there are a lot of technical issues that need to be clarified for the LWR application because the previous research on the SiCf/SiC composite has mostly been focused on high-temperature application. Especially, the corrosion resistance in the PWR water is an important parameter to insure the cladding performance under normal operating condition. Generally, SiC ceramics are highly corrosion resistant by forming a protective SiO2 layer in an air atmosphere. However, the corrosion resistance of SiC is largely dependent on the fabrication route of SiC and the exact environmental condition. For example, in a high-temperature and high-pressure water or a steam environment, the corrosion resistance of SiC is decreased because the protectiveness of the SiO2 layer is deteriorated. Until now, the exact corrosion behavior of SiC in high temperature water is not clear due to the differences in the test samples and conditions. The kinetics of the SiC corrosion in an LWR condition, therefore, needs to be defined to confirm the possibility of a burn-up extension and the cost-benefit effect of the SiC composite cladding. In this study, we evaluated the corrosion behavior of SiC-based ceramics fabricated by various routes. We also examined the effect of PWR water chemistry on the corrosion resistance of SiC

  19. The effect of surface treatment and position of the dental restoration on amalgam corrosion behavior

    International Nuclear Information System (INIS)

    The aim of this research was to evaluate the effect of surface treatment, clinical operations and the condition and position of the dental restoration on amalgam corrosion behavior. Commercial amalgam alloy namely Oralloy was selected. Twenty-one amalgam samples were prepared. After triturating and condensation, the samples were divided into three groups and each group was finished by using one of three surface clinical procedures; carving, carving-burnishing, carving-burnishing-polishing. A special cylindrical mold was used in order to simulation of the interproximal areas and proximal surfaces of the dental restorations. Stainless steel matrix band was laid on the internal mold surfaces and amalgam paste was compacted in the mold. Electrochemical potentiodynamic tests were performed at a temperature of 37±1 oC in physiological solution in order to determine and compare the corrosion behavior of dental amalgam samples, as an indication of biocompatibility. The results showed statistically significant differences between the mean corrosion current density values of three different groups of dental amalgam (P<0.05). The polished group possesses the lowest and the carved group shows the highest corrosion current density. The carved group shows more corrosion resistance in compare with the sample near the matrix band as an index of the proximal surfaces of restorations. It was concluded that even a simple clinical operation could effect on dental amalgam corrosion resistance. The proximal surfaces of the class II restorations are not only susceptible to concentration cell corrosion but also possess less corrosion resistance because dentist could perform no clinical surface treatment. (author)

  20. The effect of surface treatment and position of the dental restoration on amalgam corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Mortazavi, V. [Isfahan Univ. of Medical Sciences, Faculty of Dentistry, Isfahan (Iran, Islamic Republic of); Fathi, M.H. [Isfahan Univ. of Technology, Materials Engineering Dept., Isfahan (Iran, Islamic Republic of)

    2003-07-01

    The aim of this research was to evaluate the effect of surface treatment, clinical operations and the condition and position of the dental restoration on amalgam corrosion behavior. Commercial amalgam alloy namely Oralloy was selected. Twenty-one amalgam samples were prepared. After triturating and condensation, the samples were divided into three groups and each group was finished by using one of three surface clinical procedures; carving, carving-burnishing, carving-burnishing-polishing. A special cylindrical mold was used in order to simulation of the interproximal areas and proximal surfaces of the dental restorations. Stainless steel matrix band was laid on the internal mold surfaces and amalgam paste was compacted in the mold. Electrochemical potentiodynamic tests were performed at a temperature of 37{+-}1 {sup o}C in physiological solution in order to determine and compare the corrosion behavior of dental amalgam samples, as an indication of biocompatibility. The results showed statistically significant differences between the mean corrosion current density values of three different groups of dental amalgam (P<0.05). The polished group possesses the lowest and the carved group shows the highest corrosion current density. The carved group shows more corrosion resistance in compare with the sample near the matrix band as an index of the proximal surfaces of restorations. It was concluded that even a simple clinical operation could effect on dental amalgam corrosion resistance. The proximal surfaces of the class II restorations are not only susceptible to concentration cell corrosion but also possess less corrosion resistance because dentist could perform no clinical surface treatment. (author)

  1. Corrosion of low Si-alloyed steels in aqueous solution at 90 deg. C. Inhibitive action of silicates

    International Nuclear Information System (INIS)

    Low-Si alloyed steels, with Si content ranging from 0.25 to 3.2 wt%, as potential candidate materials for high-level nuclear waste disposal containers, have been studied four the point of view of their corrosion behaviour at 90 deg C in an aqueous solution simulating groundwater (0.1 M NaCl borate-buffered solution with a pH of 8.5) both in reducing and in aerated conditions. The influence of silicate addition to the solution is examined so as to represent the silicon of groundwater, coming from the clay dissolution. When no silicate was added to the solution, silicon as an alloying element was proved to degrade in the first moments the steel ability to passivate. For longer immersion times, protective effects developed most efficiently on the steel containing 3.2 wt% silicon both in reducing an in aerating conditions, Infrared spectroscopy, EDSX, XRD and Raman microprobe were applied to characterise the oxide layer composition, which was found to be a mixture of magnetite and maghemite. In the presence of silicate in the solution, clay-like iron silicates appeared in the corrosion layer. Electrochemical tests results show that adding silicate into solution resulted in increasing the steel ability to passivate. In the short term, the inhibiting effect of silicate was confirmed by mass loss tests, but the tendency was inverse in the long term. Silicate iron layers were eventually less protective than the magnetite layers formed in the absence of silicate. (author)

  2. Tungstate as a synergist to phosphonate-based formulation for corrosion control of carbon steel in nearly neutral aqueous environment

    Indian Academy of Sciences (India)

    B V Appa Rao; M Venkateswara Rao; S Srinivasa Rao; B Sreedhar

    2010-07-01

    Synergistic inhibition of corrosion of carbon steel in low chloride aqueous medium using tungstate as a synergist in combination with ,-(phosphonomethyl) glycine (BPMG) and zinc ions is presented. The synergistic action of tungstate has been established through the present studies. The new ternary inhibitor formulation is effective in neutral and slightly acidic as well as slightly alkaline media. Potentiodynamic polarisation studies inferred that the formulation functions as a mixed inhibitor. Impedance studies of the metal/solution interface revealed that the surface film is highly protective. Characterisation by X-ray photoelectron spectroscopy (XPS) of the surface film formed in presence of the inhibitor revealed the presence of iron, phosphorus, nitrogen, oxygen, carbon, zinc and tungsten in the surface film. The chemical shifts in the binding energies of these elements inferred that the surface film is composed of iron oxides/hydroxides, zinc hydroxide, heteropolynuclear complex [Fe(III), Zn(II)-BPMG] and WO3. Reflection absorption FTIR spectroscopic studies also supported the presence of these compounds in the surface film. Morphological features of the metal surface studied in the absence and presence of the inhibitor by scanning electron microscopy (SEM) are also presented. Based on all these results, a plausible mechanism of corrosion inhibition is proposed.

  3. Contribution to the study to the stress corrosion susceptibility of austenitic stainless steel AISI 304 in aqueous solutions containing chlorides

    International Nuclear Information System (INIS)

    The anodic behaviour of type 304 austenitic stainless steel, stressed in aqueous neutral and acid NaCl solutions, was studied. The experimental technique of the straining electrode, with constant speed and high strain rate, was applied at room temperature and at 900C. The current density on the bare metal, which is exposed to the medium during the straining the specimen, was determined at various potentials for 1N; 0,1N and 0,001N NaCl, at both temperatures, and for 1N H2SO4 + 0,1N NaCl at room temperature. In the 1N NaCl solution, tests were also carried with slightly sensitizes material at 250C and 900C. The possible crack propagation rates were estimated from these data, and parameters related with stress corrosion cracking susceptibility were analised. Potentiodynamic polarization curves were done at several potential scanning rates with and without simultaneous straining of the electrode at the same temperature, in some of the NaCl concentrations, with the aim of comparing the current values with those found in the method described above. These curves were also performed in boiling MgCl2 solutions with and without addition of NaNO3 with the purpose of compare its stress corrosion prognostic capacity in relation of that other types of tests reported. (Author)

  4. Aqueous corrosion of olivine in the Mars meteorite Miller Range (MIL) 03346 during Antarctic weathering: Implications for water on Mars

    Science.gov (United States)

    Velbel, Michael A.

    2016-05-01

    Several nakhlites (clinopyroxenite meteorites from Mars) contain olivine phenocrysts with corrosion features identical in size, shape and distribution to the smaller etch-pits of well-characterized weathered terrestrial olivine. Miller Range (MIL) 03346 is an Antarctic nakhlite find, recovered after long exposure to Antarctic conditions. The distribution of discrete olivine etch-pits almost exclusively within a few hundred microns of allocation MIL 03346,171's documentably exposed surface suggests that they formed by terrestrial weathering in Antarctica. The small size of olivine etch-pits in MIL 03346,171 relative to commonly much larger etch-pits in even incipiently weathered terrestrial examples suggests that the duration of its exposure to weathering conditions was short, or the weathering conditions to which it was exposed did not favor olivine corrosion (in the form of etch-pit formation), or both. Time-scales for the formation of etch-pits, estimated from experimentally determined dissolution rates of olivine over a range of pHs, are comparable to the measured terrestrial age of the meteorite and short relative to the time available for possible similar corrosion on Mars. Etch-pits of the observed size on MIL 03346 olivine phenocrysts would be relatively easy to form supraglacially under brief episodic acidic Antarctic conditions, but the terrestrial age of MIL 03346 is long enough that its olivine might have been weathered to the observed state by englacial films of alkaline Antarctic water. The paucity of similar etch-pits in olivine from the interior of MIL 03346 suggests that olivine in this Mars meteorite was exposed to even less aqueous alteration after iddingsitization during its 1.3 billion years on Mars than its exterior was subjected to during its Pleistocene-Holocene exposure to Antarctic weathering conditions.

  5. Corrosion behavior of titanium in contact with lead in sulphuric acid anodizing bath

    International Nuclear Information System (INIS)

    Titanium, due to its improved corrosion resistance, is frequently used for making Heat Exchangers, Jigs and Fixtures required by Electroplating Industry for anodizing of different components. However, some serious problem may be encountered in practice if titanium comes in contact with others metals. The galvanic corrosion behavior of titanium alloy in contact with pure lead directly or indirectly (i.e., two samples placed apart in the test solution and connected with titanium wire) in standard 15 % sulphuric acid anodizing bath (test solution) has been studied by weight loss method. The Electrochemical Method (ASTM G5 ) was used to supplement weight loss results. The effect of concentration of test solution on corrosion rate was also studied and the behavior of protective oxide film formed on Ti surface discussed. The present study also touched another aspect, which plays an important part in galvanic corrosion i.e., the effect of cathode/anode area ratio. An unfavorable area ratio leading to localize attack is due to formation of a large cathode/small anodic corrosion cell. The cathodic behavior of Pb was also studied to justify corrosion of titanium although it is noble in the Galvanic Series as compared to Pb. Titanium in contact with lead exhibits anodic control and its dissolution as titanium sulphate in turns increases its corrosion rate. The study also revealed that the electrolyte attacks highly at regions very close to contact and also on the welding spots, where welding is done for fabrication of heat exchanger. This is because at this point protective films is less continuous as compared to the polished surface where the films is more continuous and thus more protective. (author)

  6. Corrosion behaviour of Alloy 800 in high temperature aqueous solutions: long term autoclave studies

    Science.gov (United States)

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

    1996-04-01

    Generalized corrosion of Alloy 800 under primary coolant conditions was investigated by measuring the average thickness of oxide layers grown after long isothermal exposures in the autoclaves located out of core in the Embalse Nuclear Power Plant and shorter exposures in laboratory static autoclaves. The films exhibited the familiar double layer structure but after long exposures the inner layer was found to be hidden by the formation of overlayers and/or by the deposition of species inevitably present in high temperature coolant. The samples exposed to the primary coolant showed greater average oxide thickness than those in the static autoclave studies, indicating the deposition of corrosion products from the coolant. Analysis of the films grown in static autoclaves showed the presence of hydrated species at the oxide/solution interface and spinel structures inside the film. Oxidized nickel was found only within few nanometers in the outermost layer of the films whereas elementary nickel predominated in the rest of the oxide.

  7. Dissolution/swelling behavior of cycloolefin polymers in aqueous base

    Science.gov (United States)

    Ito, Hiroshi; Allen, Robert D.; Opitz, Juliann; Wallow, Thomas I.; Truong, Hoa D.; Hofer, Donald C.; Varanasi, Pushkara R.; Jordhamo, George M.; Jayaraman, Saikumar; Vicari, Richard

    2000-06-01

    Polycycloolefins prepared by addition polymerization of norbornene derivatives are quite different from hydroxystyrene-based polymers in terms of their interaction with aqueous base. Their dissolution kinetics monitored on a quartz crystal microbalance is not a smooth function of the ratio of the polar to nonpolar functionalities in polymer but abruptly changes from very fast dissolution to massive swelling within a narrow range of composition. The maximum swelling is a function of thickness and the entire film thickness can swell in a few seconds at > 3,000 angstroms/sec or at immeasurably fast rates. The initial concentration of a pendant carboxylic acid in polymer has to be selected to minimize swelling and the concentration of an acid-labile group to induce fast dissolution in the exposed area. Furthermore, swelling which occurs in the partially- exposed regions must be minimized by incorporating a third monomer unit or by adding a dissolution modifying agent (DMA) such as t-butyl cholate. However, the function of DMA which is also acid-labile is quite complex; depending on the matrix polymer composition and its dissolution/swelling behavior, DMA could function as a swelling suppressor or promoter and a carboxylic acid generated by acidolysis of DMA as a dissolution or swelling promoter. Photochemically generated sulfonic acid could also affect the dissolution/swelling behavior. Base hydrolysis of anhydride during development is controlled by the polarity (carboxylic acid concentration) in polymer film, which has been demonstrated in an unequivocal fashion by IR spectroscopy under the condition strongly mimicking the development process and thus could boost development contrast but could hurt performance as well. Thus, incorporation of carboxylic acid in the form of methacrylic acid, for example, in radical copolymerization of norbornene with maleic anhydride must be handled carefully as it would increase the susceptibility of the anhydride hydrolysis and could

  8. Different immersion periods and aqueous solutions effects upon the corrosion resistance of zinc and aluminium specimens

    Directory of Open Access Journals (Sweden)

    Osório, W. R.

    2005-12-01

    Full Text Available Several metallic materials form spontaneously an oxide film at the surface when is exposed in a corrosive environment. It is well known that the type of corrosive media may develop different results at the material corrosion resistance. The aim of the present paper is to investigate the influence of immersion periods and different solutions upon the corrosion resistance of pure Zn and Al specimens presenting different grain morphologies. The specimens were monitored for several periods in a 3 % NaCl solution at room temperature. Tests were also performed with variations of the 3 % NaCl solution modified by additions of acid and alkaline components. Both the electrochemical impedance spectroscopy (EIS and polarization methods were applied.

    Algunos materiales metálicos, cuando se encuentran en un entorno corrosivo, forman espontáneamente una película de óxido en su superficie. Se sabe que los medios corrosivos pueden dar resultados diferentes, según sea la resistencia a la corrosión del material. El propósito del siguiente trabajo es investigar la influencia de los períodos de inmersión en diferentes soluciones sobre la resistencia a la corrosión de probetas de cinc y aluminio puros, con morfologías de grano diferentes. Las probetas fueron ensayadas durante varios períodos de tiempo en soluciones de NaCl 3 % y también con adiciones de ácidos y bases. Se utilizaron las técnicas de espectrometría de impedancia electroquímica (EIS y de polarización.

  9. A comparative corrosion behavior of Mg, AZ31 and AZ91 alloys in 3.5% NaCl solution

    OpenAIRE

    I.B. Singh; M Singh; Das, S.

    2015-01-01

    The corrosion behavior of Mg, AZ31 and AZ91 has been evaluated in 3.5% NaCl solution using weight loss, electrochemical polarization and impedance measurements. Corrosion rate derived from the weight losses demonstrated the occurrence of steeply fast corrosion reaction on AZ91 alloy after three hours of immersion, indicating the start of galvanic corrosion. An increase of corrosion rate with immersion time was also observed for AZ31 but with lesser extent than AZ91 alloy. Whereas Mg metals sh...

  10. 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.

  11. Nuclear waste package corrosion behavior in the proposed Yucca Mountain repository

    International Nuclear Information System (INIS)

    The corrosion performance of spent nuclear fuel waste packages is becoming increasingly important in establishing the viability of the proposed Yucca Mountain repository system. Current package concepts propose the use of a 2 cm thick nickel-base superalloy (Alloy 22) shell as the main barrier to prevent corrosion penetration over many thousands of years. The expected package service conditions, as well as their variability and uncertainty, are discussed. The electrochemical conditions known to be responsible for passive behavior and its breakdown in Alloy 22 and similar alloys are examined in the light of the predicted repository environment. Durability prediction approaches and their conclusions are considered. Efforts to determine the relative impact of localized modes of failure and uniform passive dissolution on package durability are reviewed, along with open issues in need of resolution and alternative package designs. The basic question of the validity of extrapolating corrosion behavior over many times the duration of the present base of experience is addressed

  12. Corrosion Behavior of Titanium Grade 7 in Fluoride-Containing NaCl Brines

    Energy Technology Data Exchange (ETDEWEB)

    Lian, T; Whalen, M T; Wong, L

    2004-10-25

    The effects of fluoride on the corrosion behavior of Titanium Grade 7 (0.12-0.25% Pd) have been investigated. Up to 0.1 mol/L fluoride was added to the NaCl brines at 95 C, and three pH values of 4, 8, and 11 were selected for studying pH dependence of fluoride effects. It was observed that fluoride significantly altered the anodic polarization behavior, at all three pH values of 4, 8, and 11. Under acidic condition fluoride caused active corrosion. The corrosion of Titanium grade 7 was increased by three orders of magnitude when a 0.1 mol/L fluoride was added to the NaCl brines at pH 4, and the Pd ennoblement effect was not observed in acidic fluoride-containing environments. The effects of fluoride were reduced significantly when pH was increased to 8 and above.

  13. Investigation of Corrosion Behavior of Bioactive Coverings on Commercially Pure Titanium and its Alloys

    Directory of Open Access Journals (Sweden)

    M.Yu. Gazizova

    2015-12-01

    Full Text Available A microporous and macroporous bioactive coatings on boimedical titanium alloys (VT1-0, VT6, Ti-6Al-7Nb were formed by a micro-arc oxidation method. The effect of the phase composition of microporous and macroporous coatings on corrosion behavior titanium and its alloys was investigated. The results show that phase composition of the coatings microporous presented only titanium oxides: anatase and rutile, at that the phase composition macroporous coatings consists of anatase, rutile and calcium phosphate compounds: tricalcium phosphate (TCP α-Ca3(PO42 and calcium deficient hydroxyapatite Ca9HPO4(PO45OH. Corrosion behavior of MAO coatings was investigated in solution 0.9 % NaCl using potentiodynamic polarization tests. The microporous coatings exhibited a more highest corrosion resistance than macroporous coatings, it is connected with containing calcium phosphate compounds in macroporous coatings.

  14. Fission and corrosion products behavior in primary circuits of LMFBR's

    International Nuclear Information System (INIS)

    Most of the 20 presented papers report items belonging to more than one session. The equipment results of primary circuits of LMFBR's relative to corrosion and fission products, release and chemistry of fuel, measurement techniques and analytical procedures of sodium sampling, difficulties with radionuclides and particles, reactor experiences with EBR-II, FFTF, BR10, BOR60, BN350, BN600, JOYO, and KNK-II, DFR, PFR, RAPSODIE, PHENIX, and SUPERPHENIX, and at least the verification of codes for calculation models of radioactive products accumulation and distribution are described. All 20 papers presented at the meeting are separately indexed in the database. (DG)

  15. EFFECT OF CORROSION ON BOND BEHAVIOR AND BENDING STRENGTH OF REINFORCED CONCRETE BEAMS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    There is growing concern for corrosion damage in reinforced concrete structures with several decades' service. Pullout tests and beam tests were carried out to study the effect of reinforcement corrosion on the bond behavior and bending strength of reinforced concrete beams. The bond strength of plain bars and concrete initially increases with increasing corrosion, then declines. The turning point depends on the cracking of the concrete cover. The bond strength of deformed bars and concrete increases with corrosion up to a certain amount, but with progressive increase in corrosion, the bond strength decreases, and the cracking of the concrete cover seems to have no effect on the bond strength. On the basis of test data, the bond strength coefficient recommended here, which, together with the bond strength of uncorroded steel bars and concrete, can be used to easily calculate the bond strength of corroded steel bars and concrete. The bond strength coefficient proposed in this paper can be used to study the bond stress-slip relationship of corroded steel bars and concrete. The bending strength of corroded reinforced concrete beams declines with increasing reinforcement corrosion. Decreased bending strength of corroded RC beam is due to reduction in steel bar cross section, reduction of yield strength of steel bar, and reduction of bond capacity between steel bar and concrete.

  16. 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.

  17. The effect of graphite addition on corrosion behavior of tar bonded dolomite refractories in steelmaking converter

    International Nuclear Information System (INIS)

    Dolomite based refractories are widely used in Iranian steelmaking plants. In the present research, wear and corrosion of refractories used in steel-making converter lining in Esfahan Steel Company was studied. Post-mortem analysis of refractories clarified that the wear started with oxidation of carbon followed by chemical corrosion. Iron oxide from slag reacted with calcia, resulting in formation of low melting phase, and subsequent washout process, caused the refractory corrosion onset from the hut face. In addition, the effect of aluminum as an anti-oxidant and graphite on the corrosion resistance of refractory was investigated Tar-dolomite samples containing different amount of graphite (0, 4, 7, and 10 wt. %) were prepared in order to study their physical properties, before and after coking. Scanning electron microscopy micrographs employed to analyze the microstructures to determine the effect of graphite and antioxidant on corrosion behavior of the refractory. Results showed that oxidation process of carbon in the system was hindered and improved corrosion resistance by introducing graphite and antioxidant into the refractory composition

  18. The effect of Pseudoxanthomonas sp. as manganese oxidizing bacterium on the corrosion behavior of carbon steel

    International Nuclear Information System (INIS)

    The present study investigated the role of manganese oxidizing bacterium (MOB), namely Pseudoxanthomonas sp. on the corrosion behavior of carbon steel. This bacterium was isolated from sewage treatment plants and identified by biochemical and molecular methods. The electrochemical techniques such as open circuit potentiometry, electrochemical impedance spectroscopy, potentiodynamic and cyclic polarization were used to measure the corrosion rate and observe the corrosion mechanism. Also, scanning electron microscopy and X-ray diffraction studies were applied to surface analysis. This study revealed the strong adhesion of the biofilm on the metal surface in the presence of Pseudoxanthomonas sp. that enhanced the corrosion of carbon steel. X-ray diffraction patterns identified a high content of MnO2 deposition within these biofilms. This is the first report that discloses the involvement of Pseudoxanthomonas sp. as manganese oxidizing bacteria on the corrosion of carbon steel. - Highlights: ► A new type of manganese oxidizing bacteria, namely Pseudoxanthomonas sp. was indicated. ► This bacterium can create a biofilm on the part of metal surface and affect localized corrosion. ► In the presence of biofilm, the diffusion of oxygen vacancies and manganese ions has occurred.

  19. Effect of oxide structure on the corrosion behavior of HANA-6 alloys

    International Nuclear Information System (INIS)

    The burn-up extension of the nuclear fuel is desirable in the context with the economy of reactor operation, but it is hard to be realized without an improvement in the corrosion resistance of the Zr fuel claddings. Such a concern has promoted a great number of researches on the Zr fuel cladding which has produced the development of advanced Zr alloys as a substitute for the Zircaloys. In the previous result by the authors, the advanced Zr alloy, Zr-1.1wt.%Nb-0.05wt.%Cu which was named HANA-6 showed a much better corrosion resistance when compared to the Zirclaoy-4 in various corrosion conditions. However, the corrosion mechanism of the Zr alloys has not really been established so far though a number of empirical relations between the corrosion behavior and the microstructures of the alloy and oxide have been reported by many researchers. The purpose of this study is to enhance the understanding of the corrosion mechanism of Nb-containing Zr alloys

  20. Corrosion behavior of prestressing steel in a solution of 20% ammonium thiocyanate

    International Nuclear Information System (INIS)

    1400-MPa class high-strength PC wires are used for pre-stressed concrete structures. One of trusted hydrogen embrittlement tests for steel is a testing method that is provided in the FIP Report and defined in JSCE S 1201 for a test procedure. This test includes a constant load test in a 20% NH4SCN at 50degC for up to 200 hours to measure the rupture time. The test examined corrosion behavior in the early stage of the test when hydrogen concentration in steel would show a rapid increase. It was recognized that dissolved oxygen accelerated a corrosion reaction in pure oxygen atmosphere, but a 6-hour immersion test showed no notable difference in corrosion rate and corrosion potential in air and deaerated atmosphere. Polarization measurements suggested that a cathodic reaction independent of dissolved oxygen exerted a profound effect on a corrosion reaction. The analysis of corrosion products and iron ion led to a presumption that the iron-sulfide and iron oxide would precipitate concurrently in the early stage of immersion in 20% NH4SCN. (author)

  1. Influence of rare earth elements on corrosion behavior of Al-brass in marine water

    Institute of Scientific and Technical Information of China (English)

    LIN Gaoyong; ZHOU Yuxiong; ZENG Juhua; ZOU Yanming; LIU Jian; SUN Liping

    2011-01-01

    The corrosion behaviors of Al-brass in stagnant and flowing marine water as a function of combinative rare earths (Ce and La) addition were investigated by electrochemical techniques,X-ray diffraction (XRD) and scanning electron microscopy (SEM).It was demonstrated that RE elements could make the corrosion product layer more protective and strengthen the cohesion between the film and matrix in stagnant seawater.The electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) analysis confirmed that a duplex layer,which was mainly composed of an inner A12O3 with trace amounts of RE compounds and an outer basic chloride of copper or zinc like (Cu,Zn)2Cl(OH)3,Cu(OH)Cl and CuCl2·3Cu(OH)2 layer was formed on RE-contained Al-brass surface and that the inner layer was responsible for the good corrosion resistance of the alloy.While only a porous and non-protective corrosion product layer was formed on the Al-brass alloy without RE addition,which made small values of the corrosion resistance.Additionally,in flowing marine water with velocity about 2 m/s,pitting corrosion occurred on the M-brass surface and RE addition could availably decrease pitting sensitivity of the alloy.

  2. Initial corrosion behavior of a copper-clad plate in typical outdoor atmospheric environments

    Science.gov (United States)

    Yi, Pan; Xiao, Kui; Ding, Kangkang; Yan, Lidan; Dong, Chaofang; Li, Xiaogang

    2016-01-01

    A copper-clad printed circuit board (PCB-Cu) was subjected to long-term exposure test under typical Chinese atmospheric environments to study corrosion failure mechanisms. The corrosion behavior was investigated by analyzing electrochemical impedance, scanning Kelvin probes, stereo and scanning electron microscopes, and energy-dispersive spectra. Results showed that the initial surface potential was unevenly distributed. The outdoor PCB-Cu samples suffered severe corrosion caused by dust particles, contaminated media, and microorganisms after long-term atmospheric exposure. The initial localized corrosion was exacerbated and progressed to general corrosion for samples in Turpan, Beijing, and Wuhan under prolonged exposure, whereas PCB-Cu in Xishuangbanna was only slightly corroded. The tendency for electrochemical migration (ECM) of PCB-Cu was relatively low when applied with a bias voltage of 12 V. ECM was only observed in the PCB-Cu samples in Beijing. Contaminated medium and high humidity synergistically affected ECM corrosion in PCB-Cu materials. [Figure not available: see fulltext.

  3. Corrosion Embrittlement of Duralumin II Accelerated Corrosion Tests and the Behavior of High-Strength Aluminum Alloys of Different Compositions

    Science.gov (United States)

    Rawdon, Henry S

    1928-01-01

    The permanence, with respect to corrosion, of light aluminum alloy sheets of the duralumin type, that is, heat-treatable alloys containing Cu, Mg, Mn, and Si is discussed. Alloys of this type are subject to surface corrosion and corrosion of the interior by intercrystalline paths. Results are given of accelerated corrosion tests, tensile tests, the effect on corrosion of various alloying elements and heat treatments, electrical resistance measurements, and X-ray examinations.

  4. Corrosion behavior of ceramic structural materials in an electrolytic reduction process

    International Nuclear Information System (INIS)

    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 alloying structural materials. Therefore, the choice of the optimum material for the processing equipment that handles molten salt is critical. We investigated the corrosion behaviors of CaO-stabilized ZrO2 (CSZ) and mullite (Al6Si2O13) at 650degC for 168 h in molten (1, 3) wt% Li2O-LiCl. The as-received and tested specimens were examined by scanning electron microscopy/X-ray energy dispersive spectrometry and X-ray diffraction. CSZ showed a much better hot-corrosion resistance in the presence of Li2O-LiCl molten salt than mullite. The surface corrosion layers of mullite consisted of LiAlSiO4 in 1 wt% Li2O-LiCl, and a LiAlO2 phase appeared as the Li2O concentration increased to 3 wt%. Furthermore, Li2SiO3 was the only corrosion product observed at 3 wt% Li2O-LiCl. The surface corrosion layers of CSZ were composed mainly of tetragonal-ZrO2 with partial monoclinic-ZrO2 in 1 wt% Li2O-LiCl, and a Li2ZrO3 phase appeared at 3 wt% Li2O-LiCl. There was no corrosion product detached from the surface for those specimens. CSZ was beneficial for increasing the hot-corrosion resistance of the structural materials that handle high-temperature molten salts containing Li2O. (author)

  5. Study of the Corrosion Behavior of Nanocrystalline Ni-P Electrodeposited Coating

    NARCIS (Netherlands)

    Lee, H. B.; Wuu, D. S.; Lee, C. Y.; Lin, C. S.

    2010-01-01

    The corrosion behavior of electrodeposited Ni-P coating in 5 pct (in weight) NaCl solution has been studied. The microstructure of the Ni-P electrodeposit displayed a layered structure composed of nanocrystalline grains revealed by transmission electron microscopy (TEM). With the increase in polariz

  6. Modeling corrosion behavior of gas tungsten arc welded titanium alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The pitting corrosion characteristics of pulse TIG welded Ti-6Al-4V titanium alloy in marine environment were explained.Besides the rapid advance of titanium metallurgy, this is also due to the successful solution of problems associated with the development of titanium alloy welding. The preferred welding process of titanium alloy is frequently gas tungsten arc(GTA) welding due to its comparatively easier applicability and better economy. In the case of single pass GTA welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. The benefit of the process is utilized to obtain better quality titanium weldments. Four factors, five levels, central composite, rotatable design matrix are used to optimize the required number of experiments. The mathematical models have been developed by response surface method(RSM). The results reveal that the titanium alloy can form a protective scale in marine environment and is resistant to pitting corrosion. Experimental results are provided to illustrate the proposed approach.

  7. 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.

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

    International Nuclear Information System (INIS)

    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.

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

    International Nuclear Information System (INIS)

    In connection with the safe storage of high level nuclear waste, effect of H2O2 on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H2O2. The experimental results show that H2O2 increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H2O2 concentration increased, indicating that pitting resistance was decreased by the existence of H2O2 in the electrolyte. These effects of H2O2 on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H2O2 with those of O2, 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 H2O2 on the corrosion behavior were very similar to those of O2 such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. Further, H2O2 played much greater role in controlling cathodic reaction rate in neutral water environment. In acid and alkaline media, potential shifts by H2O2 were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively

  10. 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.

  11. Impact of high dose Kr+ ion irradiation on the corrosion behavior and microstructure of Zircaloy-4

    Institute of Scientific and Technical Information of China (English)

    Qian Wan; Xinde Bai; Xiaoyang Liu

    2005-01-01

    In order to investigate the ion irradiation effect on the corrosion behavior and microstructure of Zircaloy-4, the Zircaloy-4 film were prepared by electron beam deposition on the Zircaloy-4 specimen surface and irradiated by Kr ions using an accelerator at an energy of 300 keV with the dose from 1×1015 to 3×1016ions/cm2. The post-irradiation corrosion tests were conducted to rank the corrosion resistance of the resulting specimens by potentiodynamic polarization curve measurements in a 0.5 mol/L H2SO4 water solution at room temperature. Transmission electron microscopy (TEM) was employed to examine the microstructural change in the surface. The potentiodynamic tests show that with the irradiation dose increasing, the passive current density, closely related to the surface corrosion resistance, decreases firstly and increases subsequently. The mechanism of the corrosion behavior transformation is due to the amorphous phase formation firstly and the amorphous phase destruction and the polycrystalline structure formation in the irradiated surface subsequently.

  12. 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. PMID:25491859

  13. Corrosion behavior of each phase in low carbon microalloyed ferrite–bainite dual-phase steel: Experiments and modeling

    International Nuclear Information System (INIS)

    Highlights: •Establishing a model for describing the corrosion behavior of multiphase steel. •Quantitatively assessing the corrosion rate of each phase in multiphase steel. •Establishing a function to predict the surface roughness of corrosion morphology. •Defining an index to assess galvanic corrosion at phase-scale in multiphase steel. •The phase distribution affects the service safety of multiphase steel. -- Abstract: In situ observation of the initial corrosion behavior of a low carbon microalloyed ferrite–bainite dual-phase steel showed that the corrosion originated from the inside of ferrite and ferrite boundary. In addition, a model for describing the corrosion behavior of each phase in multiphase steel was established. Based on this model, a method to quantitatively assess the corrosion rate of each phase was presented by white light interference, and the relationship between the surface roughness and corrosion morphology was also established. Meanwhile, the galvanic corrosion at phase-scale and the influence of phase distribution on service safety of multiphase steel were discussed

  14. Effects of sulfur loading on the corrosion behaviors of metal lithium anode in lithium–sulfur batteries

    International Nuclear Information System (INIS)

    Highlights: • The effects of sulfur loading on the corrosion behaviors were investigated systematically. • The corrosion became severer with increasing sulfur loading or cycle times. • The corrosion films are porous and loose and cannot prevent further reaction between lithium and polysulfides. - Abstract: The corrosion behaviors in rechargeable lithium–sulfur batteries come from the reactions between polysulfides and metal lithium anode, and they are significantly influenced by the sulfur loading. While there are limited papers reported on the effects of sulfur loading on the corrosion behaviors. In this paper, the effects have been investigated systematically. The corrosion films consisted of insulating lithium ion conductors are loose and porous, so that the corrosive reactions cannot be hindered. The thickness of the corrosion layers, consequently, increased along with increasing sulfur loading or cycle times. For instance, the thickness of corrosion layers after 50 cycles was 98 μm in the cell with 5 mg sulfur while it reached up to 518 μm when the loading increased to 15 mg. The continuous deposition of corrosion products gave rise to low active materials utilization and poor cycling performance

  15. Effects of sulfur loading on the corrosion behaviors of metal lithium anode in lithium–sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yamiao; Duan, Xiaobo; Li, Yanbing; Huang, Liwu; Zhu, Ding; Chen, Yungui, E-mail: ygchen60@aliyun.com

    2015-08-15

    Highlights: • The effects of sulfur loading on the corrosion behaviors were investigated systematically. • The corrosion became severer with increasing sulfur loading or cycle times. • The corrosion films are porous and loose and cannot prevent further reaction between lithium and polysulfides. - Abstract: The corrosion behaviors in rechargeable lithium–sulfur batteries come from the reactions between polysulfides and metal lithium anode, and they are significantly influenced by the sulfur loading. While there are limited papers reported on the effects of sulfur loading on the corrosion behaviors. In this paper, the effects have been investigated systematically. The corrosion films consisted of insulating lithium ion conductors are loose and porous, so that the corrosive reactions cannot be hindered. The thickness of the corrosion layers, consequently, increased along with increasing sulfur loading or cycle times. For instance, the thickness of corrosion layers after 50 cycles was 98 μm in the cell with 5 mg sulfur while it reached up to 518 μm when the loading increased to 15 mg. The continuous deposition of corrosion products gave rise to low active materials utilization and poor cycling performance.

  16. Extract of Camellia sinensis as Green Inhibitor for the Corrosion of Mild Steel in Aqueous Solution

    Energy Technology Data Exchange (ETDEWEB)

    Fouda, Abd Elaziz S. [El-Mansoura Univ., El-Mansoura (Egypt); Mekkia, Dina; Badr, Abeer H. [Water and wastewater company, Dakahlia (Egypt)

    2013-04-15

    Corrosion inhibition of mild steel used in water station in 35 ppm aluminum sulfate and 10 ppm chloride solution by Camellia sinensis leaves extract was studied using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy techniques at 30 .deg. C. Results show that the inhibition efficiency increases with increasing concentration of the extract and decreases with increasing temperature. Inhibitive effect was afforded by adsorption of the extract's components which was found to accord with Langmuir adsorption isotherm. Inhibition mechanism is deduced from the temperature dependence of the inhibition efficiency and was further corroborated by the values of activation parameters obtained from the experimental data.

  17. Extract of Camellia sinensis as Green Inhibitor for the Corrosion of Mild Steel in Aqueous Solution

    International Nuclear Information System (INIS)

    Corrosion inhibition of mild steel used in water station in 35 ppm aluminum sulfate and 10 ppm chloride solution by Camellia sinensis leaves extract was studied using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy techniques at 30 .deg. C. Results show that the inhibition efficiency increases with increasing concentration of the extract and decreases with increasing temperature. Inhibitive effect was afforded by adsorption of the extract's components which was found to accord with Langmuir adsorption isotherm. Inhibition mechanism is deduced from the temperature dependence of the inhibition efficiency and was further corroborated by the values of activation parameters obtained from the experimental data

  18. Electrochemical study of aluminum corrosion in boiling high purity water

    Science.gov (United States)

    Draley, J. E.; Legault, R. A.

    1969-01-01

    Electrochemical study of aluminum corrosion in boiling high-purity water includes an equation relating current and electrochemical potential derived on the basis of a physical model of the corrosion process. The work involved an examination of the cathodic polarization behavior of 1100 aluminum during aqueous oxidation.

  19. Corrosion behavior of the friction-stir-welded joints of 2A14-T6 aluminum alloy

    Science.gov (United States)

    Qin, Hai-long; Zhang, Hua; Sun, Da-tong; Zhuang, Qian-yu

    2015-06-01

    The corrosion behavior of friction-stir-welded 2A14-T6 aluminum alloy was investigated by immersion testing in immersion exfoliation corrosion (EXCO) solution. Electrochemical measurements (open circuit potential, potentiodynamic polarization curves, and electrochemical impedance spectroscopy), scanning electron microscopy, and energy dispersive spectroscopy were employed for analyzing the corrosion mechanism. The results show that, compared to the base material, the corrosion resistance of the friction-stir welds is greatly improved, and the weld nugget has the highest corrosion resistance. The pitting susceptibility originates from the edge of Al-Cu-Fe-Mn-Si phase particles as the cathode compared to the matrix due to their high self-corrosion potential. No corrosion activity is observed around the θ phase (Al2Cu) after 2 h of immersion in EXCO solution.

  20. Effect of aging treatment on the exfoliation corrosion and stress corrosion cracking behaviors of 2195 Al–Li alloy

    International Nuclear Information System (INIS)

    Highlights: • The relationship between properties and microstructures of 2195 was discussed. • The optimum heat treatment of 2195 alloy is the aged at 155 °C for 14 h temper. • The EXCO process and susceptibility of 2195 alloy can be well detected by EIS. • The SCC susceptibility of 2195 alloy in 3.5% NaCl solution is low. • Mechanical action takes the dominant part in this SCC system for 2195 alloy. - Abstract: 2195 Al–Li alloy was processed by solid solution heat treatment and then aged at different temperatures, and its microstructure, mechanical properties, inter-granular corrosion (IGC), exfoliation corrosion (EXCO) and stress corrosion cracking (SCC) behaviors were observed and determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), immersion test in IGC and EXCO solutions, electrochemical impedance spectroscopy (EIS) and slow strain rate tensile (SSRT) test. The results reveal that the size and density of T1 precipitates at grain boundary are increased with increasing aging temperature whereas the density of T1 phases in grain is increased firstly and then reduced slightly. The IGC and EXCO susceptibility of 2195 alloy is increased while its SCC susceptibility in 3.5% NaCl solution is low and hardly influenced by the aging temperature. The hardness and tensile strength are increased at first and then decreased, but the elongation and static toughness values are declined with aging temperature. The optimum heat treatment for the practical application of 2195 alloy is the aged at 155 °C for 14 h temper

  1. Lithium uptake and the corrosion of zirconium alloys in aqueous lithium hydroxide solutions

    International Nuclear Information System (INIS)

    This paper reports on corrosion films on zirconium alloys that were analyzed for lithium by Atomic Absorption Spectroscopy (AAS), Secondary Ion Mass Spectrometry (SIMS), and Infrared Reflection Absorption Spectroscopy (IRAS). The oxides grown in reactor in dilute lithium hydroxide solution, specimens cut from Zircaloy, and Zr-2.5Nb alloy pressure tubes removed from CANDU (Canada Deuterium Uranium, Registered Trademark) reactors showed low concentrations of lithium (4 to 50 ppm). The lithium was not leachable in a warm dilute acid. 6Li undergoes transmutation by the 6Li(n,t)4He reaction. However, SIMS profiles for d 7Li were identical through the bulk oxide and the isotopic ratio was close to the natural abundance value. The lithium in the oxide, existing as adsorbed lithium on the surface, has been in dynamic equilibrium with lithium in the coolant, and, in spite of many Effective Full Power Years (EFPY) of operation, lithium added to the CANDU coolant at ∼2.5 ppm is not concentrating in the oxides. On the other hand, corrosion films grown in the laboratory in concentrated lithium hydroxide solutions were very porous and contained hundreds of ppm of lithium in the oxide

  2. Corrosion behavior of structural materials in liquid gallium environments

    International Nuclear Information System (INIS)

    The purpose of this work is to investigate the interaction between austenitic stainless steel such as SS-316L and liquid metals including pure Ga, Ga-14Sn-6Zn and Ga-8Sn-6Zn for the potential application of gallium for fast reactor coolants. As received and pre-oxidized specimens of SS-316L were exposed to static gallium and gallium alloys (Ga-14Sn-6Zn and Ga-8Sn-6Zn) at 500 C. degrees for up to 700 hours in air, vacuum and controlled O2 conditions. The results have shown that pre-oxidized specimens showed higher corrosion resistance than as-received specimens in terms of metal loss. The weight change and metal loss of SS-316L were generally reduced in Ga-14Sn-6Zn and Ga-8Sn-6Zn comparing to those in pure Ga. (authors)

  3. Corrosion Behavior of the Rare Earth Sealing Anodized Coating on Aluminum Alloy LY12

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Technological process of rare earth sealing anodized LY12 (2024) alloy is introduced. Corrosion behavior of the filmwas studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that thecoating remained passivity at the potential range from the open circuit potential (-780 mV) to -250 mV in NaClsolution. When the potential exceeded -200 mV, corrosion reaction happened on the coating. the results of ElSanalysis was consistent with the results of polarization curves.

  4. Corrosion Behavior of Compocasted ZA27/SiCp Composites in Sodium Chloride Solution

    OpenAIRE

    Bobić, B.; I. Bobić; A. Vencl; M. Babić; S. Mitrović

    2016-01-01

    The corrosion behavior of particulate ZA27/SiCp composites in an aerated sodium chloride solution was studied. The composites were synthesized via compocasting with addition of 1, 3 and 5 wt.% SiC particles in the matrix alloy. Composite samples were immersed for 30 days in the 3.5 wt.% NaCl solution open to the atmospheric air. Surface appearance and microstructure of the composites were examined by means of optical microscopy and scanning electron microscopy, while corrosion rates of the co...

  5. Investigation of the corrosion behavior of cooling coil material in a simulated concrete environment

    International Nuclear Information System (INIS)

    Pitting corrosion of the cooling coils embedded in the concrete roof of the waste tanks is one of the suspected causes of the recent cooling coil failures. Cyclic polarization tests were conducted to predict the threshold chloride level above which pitting would initiate. The threshold chloride level was determined to be 9000 ppM. Although these tests predict the electrochemical or corrosion behavior of the metal, they may not predict the severity of attack. Further tests which investigate the effect of the permeability of the concrete matrix on the transport of water and oxygen to the metal surface are planned to assess the severity of attack

  6. Evaluation of the corrosion behavior of the al-356 alloy in NaCl solutions

    Directory of Open Access Journals (Sweden)

    Mauricio Vásquez Rendón

    2011-01-01

    Full Text Available Cellular metals are a new class of materials with promising applications and a unique combination of physical, chemical and mechanical properties. The Al-356 alloy is used to manufacture metal foams from NaCl preforms. Despite the usefulness of these materials, their performance may be affected by corrosion due to residual salt. This paper reports the study of the behavior of the Al-356 alloy in chloride solutions by electrochemical techniques in rotating disk electrode. The cathodic reaction of oxygen reduction is the crucial stage of process dissolution of the material, which shows that is the oxygen transport which limits the corrosion process.

  7. Panel report on corrosion in energy systems

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-06-01

    Corrosion problems in high-temperature (non aqueous) energy systems, corrosion in aqueous energy systems and institutional problems inhibiting the development of corrosion science and engineering are discussed. (FS)

  8. Stress Corrosion Cracking Behavior of Cast Stainless Steels

    International Nuclear Information System (INIS)

    Casting of austenitic stainless steels offers the possibility of directly producing large and/or relatively complex structures, such as the first wall shield modules or the diverter cassette for the ITER fusion reactor. Casting offers major cost savings when compared to fabrication via welding of quarter modules machined from large forgings. However, the strength properties of such cast components are typically considered inferior to those of conventionally forged and annealed components. To improve and validate cast stainless steel as a substitute for wrought stainless steel, a development and testing program was initiated, utilizing nitrogen and manganese additions to promote improved performance. This paper focuses on the response of the first set of developmental alloys to neutron-irradiation and susceptibility to stress corrosion cracking. These cast materials may also have applications for different components in light water reactors. Results showed that all steels exhibited irradiation-induced hardening and a corresponding drop in ductility, as expected, although there is still considerable ductility in the irradiated samples. The cast steels all exhibited reduced hardening in comparison to a wrought reference steels, which may be related to a larger grain size. Higher nitrogen contents did not negatively influence irradiation performance. Regarding stress corrosion cracking susceptibility, the large difference in grain size limits the comparison between wrought and cast materials, and inclusions in a reference and archive cast alloy tests complicate analysis of these samples. Results suggest that the irradiated archive heat was more susceptible to cracking than the modified alloys, which may be related to the more complex microstructure. Further, the results suggest that the modified cast steel is at least as SCC resistant as wrought 316LN. The beneficial effect of nitrogen on the mechanical properties of the alloys remains after irradiation and is not

  9. Corrosion behavior and mechanical properties of TREX in manufacturing process of K1 and K2 cladding tube

    International Nuclear Information System (INIS)

    Corrosion behavior and mechanical properties were investigated for TREX in manufacturing process of K1 and K2 cladding tubes. K2 TREX showed better corrosion resistance than K1 TREX irrespective of annealing temperatures ranged from 580 .deg. C to 640 .deg. C. This is caused by that the cumulative annealing parameter of K1 TREX is higher than that of K2 TREX. The hardness of TREX increased by increasing annealing temperature although K1 and K2 TREXs showed the similar hardness. The effect of crystallographic orientation on the corrosion of K1 and K2 TREXs was examined. It was found that the corrosion behavior of Zr alloy depended on the crystallographic orientation of corroded plane. The plane with higher fn parameter showed better corrosion resistance, suggesting that the excellent corrosion resistance could be achieved by controlling process parameter to manufacture the cladding tube with high fn parameter

  10. Effects of Cerium and Lanthanum on the Corrosion Behavior of Al-3.0 wt.%Mg Alloy

    Science.gov (United States)

    Zhang, Xin; Wang, Zehua; Zhou, Zehua; Xu, Jianming

    2016-03-01

    Effects of rare earth elements (RE: cerium and lanthanum) on the corrosion behavior of Al-3.0 wt.%Mg alloy were investigated by electrochemical measurement and immersion test in 3.5 wt.% NaCl solution. The results indicated that a proper amount of rare earth (about 0.2 wt.%) could improve the corrosion resistance of Al-3.0 wt.%Mg alloy effectively, whereas that excessive rare earth addition would increase the corrosion rate and reduce the corrosion resistance. The corrosion behavior of Al-3.0 wt.%Mg alloys in 3.5 wt.% NaCl solution showed typical characteristics of pitting corrosion at the position of second phases. The more and the bigger the second phases, the more and the larger the pitting holes.

  11. Electrochemical corrosion behavior of ZrO2 nanocontainer incorporated PEDOT coating over 316L SS in simulated body fluid solution

    International Nuclear Information System (INIS)

    Conducting polymer coating over orthopaedic implants is given more attention in recent research scenario to enhance the biocompatibility and corrosion resistance of the implant material. In the present investigation electrochemical polymerization of 3,4 ethylenedioxy thiophene (EDOT) had been earned out over 316L SS from aqueous solution using cyclic voltammetry (CV). The formation of poly 3,4 ethylenedioxy thiophene (PEDOT) was confirmed from the appearance of characteristic stretching bands in ATR-IR studies. Scanning electron microscopic (SEM) surface morphological studies also revealed the existence of intact PEDOT film over the surface without any cracks. ZrO2 nanocontainer: (SNC-Zr) prepared via sol gel technique was incorporated into the PEDOT matrix (PEDOT/ZrO2 NC) during electrochemical polymerization to enhance the corrosion resistance. The appearance of Zr peak in energy dispersive X-ray analysis (EDAX) further confirmed the inclusion of ZrO2 nanocontainer into the PEDOl matrix. Electrochemical corrosion behavior of the PEDOT and PEDOT/ZrO2 NC was evaluated in SBF solution using potentiodynamic polarization and electrochemical impedance spectroscopy. Effect of ZrO2 inclusion in the PEDOT matrix had been studied to explore the corrosion resistance of coated alloy with respect to ZrO2 concentration. (author)

  12. New generation super alloy candidates for medical applications: corrosion behavior, cation release and biological evaluation.

    Science.gov (United States)

    Reclaru, L; Ziegenhagen, R; Unger, R E; Eschler, P Y; Constantin, F

    2014-12-01

    Three super alloy candidates (X1 CrNiMoMnW 24-22-6-3-2 N, NiCr21 MoNbFe 8-3-5 AlTi, CoNiCr 35-20 Mo 10 BTi) for a prolonged contact with skin are evaluated in comparison with two reference austenitic stainless steels 316L and 904L. Several electrochemical parameters were measured and determined (E(oc), E(corr), i(corr), b(a), b(c), E(b), R(p), E(crev) and coulometric analysis) in order to compare the corrosion behavior. The cation release evaluation and in vitro biological characterization also were performed. In terms of corrosion, the results reveal that the 904L steels presented the best behavior followed by the super austenitic steel X1 CrNiMoMnW 24-22-6-3-2 N. For the other two super alloys (NiCr and CoNiCr types alloys) tested in different conditions (annealed, work hardened and work hardened+age hardened) it was found that their behavior to corrosion was weak and close to the other reference stainless steel, 316L. Regarding the extraction a mixture of cations in relatively high concentrations was noted and therefore a cocktail effect was not excluded. The results obtained in the biological assays WST-1 and TNF-alpha were in correlation with the corrosion and extraction evaluation. PMID:25491846

  13. Effect of zirconium content on the microstructure, physical properties and corrosion behavior of Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Han, Mi-Kyung; Hwang, Moon-Jin [Department of Dental Materials and MRC for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Yang, Min-Soo; Yang, Hong-So [Department of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Song, Ho-Jun [Department of Dental Materials and MRC for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Park, Yeong-Joon, E-mail: yjpark@jnu.ac.kr [Department of Dental Materials and MRC for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 500-757 (Korea, Republic of)

    2014-10-20

    A series of Ti–xZr alloys with Zr contents ranging from 5 to 20 wt% was prepared and the effects of Zr addition on the microstructure, physical properties, and corrosion behavior of Ti alloys were investigated. The phase and microstructures were characterized using X-ray diffractometry (XRD), optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The Ti–xZr alloys exhibited α-Ti structure at Zr content of 20 wt% or below. Commercially pure titanium (cp-Ti) was used as a control. We also investigated the effects of alloying element Zr on the mechanical property, oxidation protection ability, and corrosion behavior of Ti–xZr binary alloys. The physical properties and corrosion behavior of Ti–xZr alloys were sensitive to the Zr content. The addition of Zr did contribute to the hardening of cp-Ti due to solid-solution strengthening of α-Ti. Ti–xZr alloys containing up to 10 wt% Zr resulted in good oxidation resistance, while Ti–xZr alloys with above 10 wt% Zr demonstrated higher oxidation weight gain than cp-Ti. Electrochemical experiments showed that the Ti–xZr alloys exhibited better corrosion resistance compared to that of cp-Ti.

  14. Effect of zirconium content on the microstructure, physical properties and corrosion behavior of Ti alloys

    International Nuclear Information System (INIS)

    A series of Ti–xZr alloys with Zr contents ranging from 5 to 20 wt% was prepared and the effects of Zr addition on the microstructure, physical properties, and corrosion behavior of Ti alloys were investigated. The phase and microstructures were characterized using X-ray diffractometry (XRD), optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The Ti–xZr alloys exhibited α-Ti structure at Zr content of 20 wt% or below. Commercially pure titanium (cp-Ti) was used as a control. We also investigated the effects of alloying element Zr on the mechanical property, oxidation protection ability, and corrosion behavior of Ti–xZr binary alloys. The physical properties and corrosion behavior of Ti–xZr alloys were sensitive to the Zr content. The addition of Zr did contribute to the hardening of cp-Ti due to solid-solution strengthening of α-Ti. Ti–xZr alloys containing up to 10 wt% Zr resulted in good oxidation resistance, while Ti–xZr alloys with above 10 wt% Zr demonstrated higher oxidation weight gain than cp-Ti. Electrochemical experiments showed that the Ti–xZr alloys exhibited better corrosion resistance compared to that of cp-Ti

  15. Hot corrosion behavior of platinum-modified nickel- and cobalt-based alloys and coatings

    Science.gov (United States)

    Deodeshmukh, Vinay Prakash

    High temperature degradation by hot corrosion (650-1000°C) and/or oxidation (>1000°C) can severely reduce the longevity of advanced gas turbine engine components. The protection of high-temperature components against hot corrosion or oxidation is typically conferred by the application of either a diffusion or overlay metallic coating that is able to form a continuous, adherent, and slow-growing oxide scale. There are currently no coatings that provide adequate protection to both hot corrosion and oxidation. Indeed, there is a particular need for such protective coatings because many advanced aero, marine, and industrial gas-turbines operate in both hot corrosion and oxidation regimes in their duty cycle. Recent work at Iowa State University (ISU) has showed that a wide range Pt+Hf-modified gamma'-Ni3Al + gamma-Ni alloy compositions form a very adherent and slow-growing Al 2O3 scale. In fact, the results reported suggest that Pt+Hf-modified gamma' + gamma coatings offer a viable superior alternative to beta-NiAl(Pt)-based coatings. The main thrust of this study was to assess and establish optimum target gamma' + gamma coating compositions for extending the service life of high-temperature gas turbine components exposed to hot corrosion and oxidation conditions. Both high temperature hot-corrosion (HTHC-900°C) and low temperature hot-corrosion (LTHC-705°C) behaviors of the Pt+Hf-modified gamma' + gamma alloys were assessed. The salt used to bring about hot corrosion was Na 2SO4. Quite interestingly, it was found that the HTHC resistance of gamma' + gamma alloys improved with up to about 10 at.% Pt addition, but then decreased significantly with increasing Pt content up to 30 at.% (the maximum level studied); however, under LTHC conditions the resistance of gamma' + gamma alloys improved with increasing Pt content up to 30 at.%. To further improve hot corrosion resistance of Pt+Hf-modified gamma' + gamma alloys, the effects of systematic additions of Cr, Si, and

  16. Corrosion Behavior of Commercial Aluminum Alloy Processed by Equal Channel Angular Pressing

    Directory of Open Access Journals (Sweden)

    Atef Korchef

    2013-01-01

    Full Text Available A commercial aluminum alloy was subjected to severe plastic deformation through equal channel angular pressing (ECAP. The alloy contains a low volume fraction of α-AlFeSi located essentially at the grain boundaries. The corrosion behavior of the ECAP’ed alloy was investigated in NaCl solution using potentiodynamic polarization and immersion tests. The effects of scan rate and NaCl concentration on the alloy susceptibility to corrosion were also studied. The results obtained were compared with those of the nonpressed alloy. ECAP leads to an intensive grain refinement accompanied by an increased dislocation density. All electrochemical tests confirm that corrosion resistance of the alloy remarkably diminished with increasing the ECAP number of passes. This is presumably due to the breakdown of the α-AlFeSi after ECAP leading to higher number of galvanic cells and enhanced dissolution of the aluminum matrix.

  17. Study of Pitting Corrosion Behavior of FSW weldments of AA6101- T6 Aluminium Alloy

    Directory of Open Access Journals (Sweden)

    L.V. Kamble

    2015-09-01

    Full Text Available Friction Stir Welding (FSW is a promising solid state joining process widely used generally for Al alloys, especially in aerospace, marine and automobile applications. In present work, the microstructure and corrosion behavior of friction stir welded AA6101 T6 Al alloy is studied. The friction stir welding was carried using vertical milling machine with different tool rotational speeds and welding speeds. The microstructure at weld nugget or stir zone (SN, thermo-mechanically affected zone (TMAZ, heat affected zone (HAZ and base metal were observed using optical microscopy. The corrosion tests of base alloy and welded joints were carried out in 3.5% NaCl solution at temperature of 30º C. Corrosion rate and emf were determined using cyclic polarization measurement.

  18. Corrosion behavior of CuCrNiAl alloy in HCl solutions

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The corrosion behavior of a CuCrNiAl alloy in HCl solutions was studied by means of metallograph, XRD, SEM/EDX and TEM methods. The results show that in low concentration of HCl solutions, Cu of CuCrNiAl alloy is more easily subject to corrsion than Cr; the dechromisation of the CuCrNiAl alloy occurs at a certain concentration of HCl solutions, at the same time Al of CuCrNiAl alloy is subject to corrosion also. The dechromisation corrosion occurs initially at the interface between Cr phase and Cu phase, then it gradually extends Cr phase until Cr phase is dissolved completely. It is also revealed that the tendency of dechromisaion of the CuCrNiAl alloy increases with the increase in concentration and temperature of HCl solutions.

  19. Electrochemical synthesis and corrosion behavior of thin polyaniline film on mild steel, copper and aluminum

    Directory of Open Access Journals (Sweden)

    Elkais Ali Ramadan

    2011-01-01

    Full Text Available The electrochemical synthesis of polyaniline (PANI on mild steel, aluminum and copper from the sodium benzoate solutions has been investigated. It has been shown that thin, highly adherent, polyaniline films on the investigated metals could be obtained by anodic oxidation with current densities in the range of 0.5 and 1.5 mA cm-2. The corrosion behavior of mild steel, aluminum and copper with polyaniline coating in 0.5 mol dm3 NaCl (pH 3 solutions, has been investigated by polarization technique. The corrosion current densities, porosity and protection efficiency was determined. It has been shown that polyaniline coating provided corrosion protection of all mentioned metals.

  20. Study of corrosion behavior for nitrocarburized sintered Astaloy CrM + C

    International Nuclear Information System (INIS)

    Salt bath nitriding/nitrocarburizing is a surface treatment developed to improve tribological and corrosion properties of ferrous materials. In this research, sintered Astaloy CrM + 0.3% C samples were nitrocarburized at 580 deg. C for 1, 1.5, 2 and 2.5 h. The microstructure and phase composition of the surface layer was investigated by optical and scanning microscopy and X-ray diffraction. Corrosion behavior of samples was evaluated using both potentiodynamic polarization technique and electrochemical impedance spectroscopy in 3.5% sodium chloride solution. XRD analyses indicate that the surface layer in nitrocarburized samples is mainly composed of ε-iron carbonitride (Fe2-3(CN)). The results reveal that salt bath nitrocarburizing for at least 2 h can improve significantly corrosion resistance of sintered Astaloy CrM + C.

  1. CORROSION BEHAVIOR OF A CONVERSION COATING BASED ON ZIRCONIUM AND COLORANTS ON GALVANIZED STEEL BY ELECTRODEPOSITION

    Directory of Open Access Journals (Sweden)

    Josiane Soares Costa

    2015-06-01

    Full Text Available Corrosion performance of Zr-based coating on substrates obtained by zinc electrodeposition in an alkaline bath is compared to chromate coatings (Cr III and Cr VI. The “nano Zr” is a conversion coating formed by immersion in a hexafluorozirconic acid solution. Since the “nano Zr” coating is transparent, the addiction of a colorant provides color to the surface. In this case, the colorant, when applied after the conversion coating, conferred the yellow color to the surface. The coating produced improves the corrosion protection of the substrate. For this study the samples were analyzed by electrochemical impedance spectroscopy (EIS and accelerated corrosion test in a humidity chamber. The results showed similar behaviors between the “nano Zr”, colorant and the chromate (Cr III coating. Therefore this kind of conversion coating is a promising substitute for chromate coatings.

  2. Corrosion behavior of alloy 600 coupled with electrodeposited magnetite in simulated secondary water of PWRs

    International Nuclear Information System (INIS)

    The corrosion behavior of Alloy 600 coupled with magnetite was investigated in simulated secondary water of pressurized water reactors using a potentiodynamic polarization test and zero-resistance ammeter. Passive film formed on the surface of Alloy 600 was also analyzed using X-ray photoelectron spectroscopy. Alloy 600 was the anodic element of the galvanic pair since its corrosion potential was less noble than that of the magnetite. Galvanic coupling increased the corrosion current density of Alloy 600 due to the shifting of the potential of Alloy 600 to the positive value. The passive film of coupled Alloy 600 was more slowly stabilized and was thinner and less protective than that of non-coupled Alloy 600. (author)

  3. An aqueous, polymer-based redox-flow battery using non-corrosive, safe, and low-cost materials

    Science.gov (United States)

    Janoschka, Tobias; Martin, Norbert; Martin, Udo; Friebe, Christian; Morgenstern, Sabine; Hiller, Hannes; Hager, Martin D.; Schubert, Ulrich S.

    2015-11-01

    For renewable energy sources such as solar, wind, and hydroelectric to be effectively used in the grid of the future, flexible and scalable energy-storage solutions are necessary to mitigate output fluctuations. Redox-flow batteries (RFBs) were first built in the 1940s and are considered a promising large-scale energy-storage technology. A limited number of redox-active materials--mainly metal salts, corrosive halogens, and low-molar-mass organic compounds--have been investigated as active materials, and only a few membrane materials, such as Nafion, have been considered for RFBs. However, for systems that are intended for both domestic and large-scale use, safety and cost must be taken into account as well as energy density and capacity, particularly regarding long-term access to metal resources, which places limits on the lithium-ion-based and vanadium-based RFB development. Here we describe an affordable, safe, and scalable battery system, which uses organic polymers as the charge-storage material in combination with inexpensive dialysis membranes, which separate the anode and the cathode by the retention of the non-metallic, active (macro-molecular) species, and an aqueous sodium chloride solution as the electrolyte. This water- and polymer-based RFB has an energy density of 10 watt hours per litre, current densities of up to 100 milliamperes per square centimetre, and stable long-term cycling capability. The polymer-based RFB we present uses an environmentally benign sodium chloride solution and cheap, commercially available filter membranes instead of highly corrosive acid electrolytes and expensive membrane materials.

  4. An aqueous, polymer-based redox-flow battery using non-corrosive, safe, and low-cost materials.

    Science.gov (United States)

    Janoschka, Tobias; Martin, Norbert; Martin, Udo; Friebe, Christian; Morgenstern, Sabine; Hiller, Hannes; Hager, Martin D; Schubert, Ulrich S

    2015-11-01

    For renewable energy sources such as solar, wind, and hydroelectric to be effectively used in the grid of the future, flexible and scalable energy-storage solutions are necessary to mitigate output fluctuations. Redox-flow batteries (RFBs) were first built in the 1940s and are considered a promising large-scale energy-storage technology. A limited number of redox-active materials--mainly metal salts, corrosive halogens, and low-molar-mass organic compounds--have been investigated as active materials, and only a few membrane materials, such as Nafion, have been considered for RFBs. However, for systems that are intended for both domestic and large-scale use, safety and cost must be taken into account as well as energy density and capacity, particularly regarding long-term access to metal resources, which places limits on the lithium-ion-based and vanadium-based RFB development. Here we describe an affordable, safe, and scalable battery system, which uses organic polymers as the charge-storage material in combination with inexpensive dialysis membranes, which separate the anode and the cathode by the retention of the non-metallic, active (macro-molecular) species, and an aqueous sodium chloride solution as the electrolyte. This water- and polymer-based RFB has an energy density of 10 watt hours per litre, current densities of up to 100 milliamperes per square centimetre, and stable long-term cycling capability. The polymer-based RFB we present uses an environmentally benign sodium chloride solution and cheap, commercially available filter membranes instead of highly corrosive acid electrolytes and expensive membrane materials. PMID:26503039

  5. Study of the corrosion behavior and the corrosion films formed on the surfaces of Mg–xSn alloys in 3.5 wt.% NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jingfeng, E-mail: jfwang@cqu.edu.cn; Li, Yang; Huang, Song; Zhou, Xiaoen

    2014-10-30

    Highlights: • Corrosion of four cast Mg–xSn alloys in 3.5 wt.% NaCl solution was investigated. • Both Mg(OH){sub 2}/SnO{sub 2} corrosion product film and Mg(OH){sub 2}/MgSnO{sub 3} clusters formed on Mg–1.5Sn. • Compact Mg(OH){sub 2}/MgSnO{sub 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){sub 2}/SnO{sub 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){sub 2}/SnO{sub 2} corrosion product film and Mg(OH){sub 2}/MgSnO{sub 3} clusters formed on Mg–1.5Sn alloy surface. Mg(OH){sub 2}/MgSnO{sub 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){sub 2}/SnO{sub 2} corrosion product film during the corrosion process.

  6. Nanoscale surface characterization of aqueous copper corrosion: Effects of immersion interval and orthophosphate concentration

    International Nuclear Information System (INIS)

    Morphology changes for copper surfaces exposed to different water parameters were investigated at the nanoscale with atomic force microscopy (AFM), as influenced by changes in pH and the levels of orthophosphate ions. Synthetic water samples were designed to mimic physiological chemistries for drinking water, both with and without addition of orthophosphate over a pH range 6.5–9. Copper surfaces treated with orthophosphate as a corrosion inhibitor after 6 and 24 h were evaluated. Tapping mode AFM images revealed dosing of the water with 6 mg/L of orthophosphate was beneficial in retarding the growth of copper by-products. The chemical composition and oxidation state of the surface deposits were characterized with X-ray diffraction (XRD), near edge X-ray absorption fine structure (NEXAFS) spectroscopy and Fourier transform infrared spectroscopy (FTIR).

  7. Effect of tritium on corrosion behavior of chromium in 0.01 N sulfuric acid solution

    International Nuclear Information System (INIS)

    The effects of tritium on the corrosion behavior of chromium in 0.01 N sulfuric solution have been investigated in the present study. Electrochemical experiments have been carried our for pure chromium. At first, the concentration dependence of sulfuric acid solution on anodic polarization behavior of chromium was experimented, resulting in that 0.01 N one was found appropriate. The dependence of both dissolved oxygen and tritium concentration on anodic behavior of chromium were performed. It was found from that the self-passivation of chromium induced by dissolved oxygen was inhibited in tritiated solution resulting in the enhancement of the corrosion. As a consequence it is highly likely that the elution of chromium by highly oxidative radiolysis products would explain the passivation inhibitory effect of SUS304 stainless steel observed in tritiated solutions

  8. Corrosion behavior of Zircaloy-4 sheets produced under various hot-rolling and annealing conditions

    International Nuclear Information System (INIS)

    The uniform corrosion resistance of Zircaloy-4 sheets produced under various hot-rolling and annealing conditions was investigated. The uniform corrosion resistance in static steam at 673 K improved with an increasing cumulative annealing parameter (ΣA). However, to clarify the physical meaning of the annealing parameter and the different combinations of various heating stages, the effects of individual manufacturing conditions that influence the corrosion behavior and ripening behavior of the precipitates were investigated. As a result, the annealing temperature after hot-rolling influenced the uniform corrosion more significantly than the intermediate annealing and the final annealing temperatures. Size distributions of the intermetallic compound precipitates that were observed by means of a scanning electron microscope (SEM) with an image analyzer were examined for a correlation with weight gain. The percentage of small precipitates below 100 nm in size was important in determining corrosion resistance and had a good correlation with the annealing parameter; that is, if the percentage was lower than 30%, the corrosion resistance was satisfactory. Also, the frequency of precipitates under 100 nm in size decreased sharply with increasing annealing temperature after hot-rolling. The intermetallic compounds that were incorporated into the ZrO2 oxide scale and the scale/metal interface were observed by a transmission electron microscope (TEM). The incorporated intermetallic precipitates were observed to have changed their composition; that is, the iron content decreased and the iron/chromium (Fe/Cr) ratio for the zirconium-chromium-iron intermetallic precipitate was approximately 1 compared to approximately 2 in the Zircaloy matrix. During oxidation, iron from the intermetallic compound precipitates scattered more into the oxide than chromium

  9. Corrosion behavior of Zr modified CrN coatings using metal vapor vacuum arc ion implantation

    International Nuclear Information System (INIS)

    In recent years, attention has focused on the use of alternative metal nitride coatings as replacements for TiN for not only improved wear resistance and surface hardness but also for increased corrosion resistance in selected environments. While these coatings display excellent wear resistance and surface hardness, like many nitride coatings, their corrosion behavior is determined to a large extent by the presence of defects such as pinholes within the coating. Improved corrosion resistance is expected through minimizing the porosity/number of pinholes within the coating, through postdeposition surface modification. The aim of this study was to modify the surface of CrN coatings using metal vapor vacuum arc ion implantation. CrN coatings were deposited on AISI 316 stainless steel and AISI 1020 mild steel substrates using physical vapor deposition technology, followed by implantation of Zr ions into the coating at doses varying from 6x1016 to 2x1017 ions/cm2. The corrosion behavior was assessed in saline environments using linear polarization techniques and the corroded surface of the coatings was characterized using x-ray photoelectron spectroscopy and scanning electron microscopy. The results of the study showed that implantation of Zr ions into CrN resulted in a lowering of the corrosion current density, suggesting improved corrosion resistance. This was though to be associated with two factors. Firstly, partial closure of the pinholes as a result of the implantation process and secondly, the formation of ZrN, CrZrN, and various oxynitrides/oxides at the surface

  10. 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. PMID:26354269

  11. Electrochemical corrosion behavior of the carburized porous TiAl alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Cuijiao [Hunan University of Technology, Zhuzhou, Hunan 412000 (China); Yang, Junsheng [Wuhan Polytechnic University, Wuhan, Hubei 430023 (China); He, Yuehui, E-mail: yuehui@mail.csu.edu.cn [State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Ming, XingZu [Hunan University of Technology, Zhuzhou, Hunan 412000 (China)

    2015-01-15

    Highlights: • Ti{sub 2}AlC phase forms on porous TiAl alloy in a carburizing atmosphere. • The carburized sample at 1203 K for 10 h has continuous carburized layers. • Carburization can improve corrosion resistance of the porous TiAl alloy. • The passive film of the carburized sample at 1203 K for 10 h is very stable. - Abstract: Carburization was carried out to improve corrosion resistance of porous Ti–46.5 Al (at.%) intermetallic compound. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) were applied to analyze the carburized layers. Electrochemical corrosion behavior of the untreated and the carburized samples were investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and open circuit potential. The results reveal that the continuous and thick carburized layers form after carburization treatment at 1203 K for 10 h, whose main phase is a functional complex ceramic phase, Ti{sub 2}AlC. Carburization can improve corrosion resistance of the porous TiAl alloy. Among the carburized samples, the carburized one at 1203 K for 10 h presents the highest corrosion resistance and has the most stable oxide film.

  12. Corrosion behavior of Zr(Fe, Cr)2 metallic compounds in 500 degree C superheated steam

    International Nuclear Information System (INIS)

    Zr(Fe, Cr)2 metallic compounds with different Fe/Cr ratio of 1.75 and 4.50 were prepared by non-consumable arc melting. X-ray diffraction, electron microprobe and transmission electron microscopy were employed for analyzing the corrosion products, the composition distribution and structure morphology after corrosion test of Zr(Fe, Cr)2 metallic compound powder at 500 degree C superheated steam with different exposure time. The corrosion products are the same for Zr(Fe, Cr)2 with different Fe/Cr ratio, but the corrosion resistant is better for Fe/Cr ratio of 1.75 than that of 4.50. Cubic ZrO2 and alpha Fe(Cr) are formed at the beginning of Zr(Fe, Cr)2 oxidation, then monoclinic ZrO2 transformed from cubic ZrO2 and (Fe, Cr)3O4 are observed at the late stage of oxidation. When the segregation of iron and chromium atoms occurs during the oxidation of Zr(Fe, Cr)2 metallic compounds, the diffusion rate of iron atoms is faster than that of chromium atoms. Based on the results obtained in present work, the effect of second phase particles on the corrosion behavior of Zircaloy-4 has been discussed

  13. Corrosion behavior of TiN coated type 316 stainless steel in simulated PEMFC environments

    International Nuclear Information System (INIS)

    The corrosion behavior of TiN coated type 316 stainless steel (SS) was investigated in simulated proton exchange membrane fuel cell environments, i.e. 0.01 M HCl + 0.01 M Na2SO4 solutions bubbled with pure oxygen and hydrogen gases, respectively, by using electrochemical measurement techniques. 316SS substrate can passivate spontaneously in simulated cathode environment, while it is in active state at the corrosion potential in simulated anode environment. TiN coatings have much better corrosion resistance and passivity under both simulated conditions. No significant degradation takes place in TiN coatings under the typical load conditions of fuel cell for 4 h. The loss of small part of coatings occurs during the immersion tests of TiN coatings in the oxygen environment for 1000 h and in the hydrogen environment for 240 h, respectively, but the exposed substrate areas are passivated in both environments. The results reveal that TiN coating can offer 316SS higher corrosion resistance and electric conductivity, and that further effort to improve the coating quality and to evaluate the long-term stability of 316SS/TiN coating systems under simulated conditions are deserved. In addition, the characteristics of corrosion process for TiN coatings on passivatable substrate were discussed in detail

  14. Surface properties and corrosion behavior of Co-Cr alloy fabricated with selective laser melting technique.

    Science.gov (United States)

    Xin, Xian-zhen; Chen, Jie; Xiang, Nan; Wei, Bin

    2013-01-01

    We sought to study the corrosion behavior and surface properties of a commercial cobalt-chromium (Co-Cr) alloy which was fabricated with selective laser melting (SLM) technique. For this purpose, specimens were fabricated using different techniques, such as SLM system and casting methods. Surface hardness testing, microstructure observation, surface analysis using X-ray photoelectron spectroscopy (XPS) and electrochemical corrosion test were carried out to evaluate the corrosion properties and surface properties of the specimens. We found that microstructure of SLM specimens was more homogeneous than that of cast specimens. The mean surface hardness values of SLM and cast specimens were 458.3 and 384.8, respectively; SLM specimens showed higher values than cast ones in hardness. Both specimens exhibited no differences in their electrochemical corrosion properties in the artificial saliva through potentiodynamic curves and EIS, and no significant difference via XPS. Therefore, we concluded that within the scope of this study, SLM-fabricated restorations revealed good surface properties, such as proper hardness, homogeneous microstructure, and also showed sufficient corrosion resistance which could meet the needs of dental clinics. PMID:23553145

  15. In vitro corrosion behavior and cellular response of thermally oxidized Zr-3Sn alloy

    Science.gov (United States)

    Zhou, F. Y.; Wang, B. L.; Qiu, K. J.; Li, H. F.; Li, L.; Zheng, Y. F.; Han, Y.

    2013-01-01

    In this study, ZrSn alloy was thermally oxidized at 600 °C for 3 h and its morphological and structural characteristics, corrosion behavior, ion release and in vitro cytocompatibility were studied to evaluate the feasibility of applying it as dental implant. After oxidation, a dense black oxide layer formed on ZrSn alloy surface, which consisted of predominant monoclinic zirconia and a few non-stoichiometric oxides. The scratching and water contact angle test results demonstrated that the oxide layer exhibited good adhesion strength and similar hydrophilicity to zirconia. The oxidized ZrSn alloy showed higher corrosion resistance, as indicated by far lower corrosion current density and passive current density compared to pure Ti and untreated ZrSn alloy in artificial saliva with and without H2O2. The amount of ions released from the oxidized ZrSn alloy was much lower than that dissolved from pure Ti in simulated corrosive oral mediums. Moreover, the oxidized ZrSn alloy did not present any significant toxic effect to both osteoblast-like cells and fibroblast cells, and osteoblast-like cells could adhere well onto the surface and exhibited a good proliferative pattern. The combination of improved surface properties, superior corrosion resistance and good biocompatibility made the oxidized ZrSn alloy promising for oral implantology application.

  16. Corrosion behavior of pristine and added MgB2 in Phosphate Buffered Saline Solution

    International Nuclear Information System (INIS)

    We have obtained by Spark Plasma Sintering (SPS), dense samples of MgB2 added with Ho2O3. Starting composition was (MgB2)0.975(HoO1.5)0.025 and we used addition powders with an average particle size below and above 100 nm. For Mg, pristine and added MgB2 samples we measured potentiodynamic polarization curves in Phosphate Buffered Saline (PBS) solution media at room temperature. MgB2 based composites show corrosion/ degradation effects. This behavior is in principle similar to Mg based alloys in the same media. Our work suggests that the different morphologies and phase compositions of the SPS-ed samples influence the interaction with corrosion medium; hence additions can play an important role in controlling the corrosion rate. Pristine MgB2 show a significant improvement of the corrosion resistance, if compared with Mg. The best corrosion resistance is obtained for pristine MgB2, followed by MgB2 with nano-Ho2O3 and μ-Ho2O3 additions.

  17. In situ ellipsometric investigation of stainless steel corrosion behavior in buffered solutions with amino acids

    Science.gov (United States)

    Vinnichenko, M. V.; Pham, M. T.; Chevolleau, T.; Poperenko, L. V.; Maitz, M. F.

    2003-02-01

    The corrosion of metals is associated both with a release of ions and changes in optical surface properties. In this study, these two effects were correlated by a potentiodynamic corrosion test and in situ probing of the surface by ellipsometry. The studies were carried out with stainless steel (SS) AISI 304 and 316 in phosphate buffered saline (PBS) and in Dulbecco's modified minimal essential medium (DMEM) at pH 7.4. In both media, 304 steel is more susceptible to corrosion than 316 grade. The 316 steel shows a higher corrosion potential and higher corrosion current density in PBS than in DMEM, for 304 steel this behavior is vice versa. Ellipsometry demonstrated a higher sensitivity than potentiodynamics to surface modification in the cathodic area. In DMEM the removal of a surface layer at negative potential and a further repassivation with increasing potential was characteristic. In PBS a surface layer started to grow immediately. X-ray photoelectron spectra of this layer formed in PBS are consistent with iron phosphate. Its formation is inhibited in DMEM; the presence of amino acids is discussed as the reason.

  18. Predicted Fracture Behavior of Shaft Steels with Improved Corrosion Resistance

    Directory of Open Access Journals (Sweden)

    Goran Vukelic

    2016-02-01

    Full Text Available One of the crucial steps in the shaft design process is the optimal selection of the material. Two types of shaft steels with improved corrosion resistances, 1.4305 and 1.7225, were investigated experimentally and numerically in this paper in order to determine some of the material characteristics important for material selection in the engineering design process. Ultimate tensile strength and yield strength have been experimentally obtained, proving that steel 1.4305 has higher values of both. In addition, J-integral is numerically determined as a measure of crack driving force for finite element models of standardized fracture specimens (single-edge notched bend and disc compact tension. Obtained J values are plotted versus specimen crack growth size (Δa for different specimen geometries (a/W. Higher resulting values of J-integral for steel 1.4305 as opposed to 1.7225 can be noted. Results can be useful as a fracture parameter in fracture toughness assessment, although this procedure differs from experimental analysis.

  19. Microstructure and corrosion behavior of Mg-Zn-Ag alloys

    International Nuclear Information System (INIS)

    The majority of Mg components currently in use in the automotive and electronic industries are produced by conventional casting processes. However, there is a strong need to develop new high strength wrought alloys for wide-spread application of Mg alloys in near future. In the present study, new Mg-Zn-Ag alloys were developed and characterized. In order to evaluate the effects of Ag addition on the mechanical properties of the extruded Mg-Zn alloys, the age hardening response and mechanical properties were examined with different amounts of alloying element. The microstructures of the specimens were examined with optical microscopy and transmission electron microscopy. The grain sizes of the alloys in as-extruded condition were markedly reduced with the addition of Ag. The hardness was found to increase more rapidly in the alloys with double aging treatment compared to those with single aging treatment. The peak hardness was also found to be higher in the alloys with double aging treatment. In all heat treatment conditions, the hardnesses of the Mg-Zn-Ag alloys were found to be higher than those of the Mg-Zn alloys. Moreover, the addition of Ag to the Mg-Zn alloys increased the corrosion rate measured by immersion test

  20. High Temperature Corrosion Behavior of Iron Aluminide Alloys and Coatings

    International Nuclear Information System (INIS)

    A multi-year effort has been focused on optimizing the long-term oxidation performance of ingot-processed (IP) and oxide-dispersion strengthened (ODS) Fe(sub 3)Al and iron aluminide-based coatings. Based on results from several composition iterations, a Hf-doped alloy (Fe-28Al-2Cr-0.05at.%Hf) has been developed with significantly better high temperature oxidation resistance than other iron aluminides. The scale adhesion is not significantly better; however, the(alpha)-Al(sub 2)O(sub 3) scale grows at a slower rate, approximately a factor of 10 less than undoped iron aluminide. The benefit of Hf is greatest at 1100-1200 C. Long-term oxidation resistance of commercially fabricated ODS Fe(sub 3)Al has been determined and compared to commercially available ODS FeCrAl. Scale spallation rates for ODS Fe(sub 3)Al are higher than for ODS FeCrAl. To complement studies of iron-aluminide weld-overlay coatings, carbon steel was coated with Fe-Al-Cr by thermal spraying. These specimens were then exposed in air at 900 and 1000 C and in air-1%SO(sub 2) at 800 C. Most likely due to an inadequate aluminum concentration in the coatings, continuous protective Al(sub 2)O(sub 3) could not be maintained and, consequently, the corrosion performance was significantly worse than what is normally observed for Fe(sub 3)Al

  1. Corrosion/95 conference papers

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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.

  3. Study of the aqueous corrosion mechanisms and kinetics of the AlFeNi aluminium based alloy used for the fuel cladding in the Jules Horowitz research reactor

    International Nuclear Information System (INIS)

    For the Jules Horowitz new material-testing reactor (JHR), an aluminium base alloy, called AlFeNi, will be used for the cladding of the fuel plates. This alloy (Al - 1% Fe - 1% Ni - 1 % Mg), which is already used as fuel cladding, was developed for its good corrosion resistance in water at high temperatures. However, few studies dealing with the alteration process in water and the relationships with irradiation effects have been performed on this alloy. The conception of the JHR fuel requires a better knowledge of the corrosion mechanisms. Corrosion tests were performed in autoclaves at 70 C, 165 C and 250 C on AlFeNi plates representative of the fuel cladding. Several techniques were used to characterize the corrosion scale: SEM, TEM, EPMA, XRD, Raman spectroscopy. Our observations show that the corrosion scale is made of two main layers: a dense amorphous scale close to the metal and a porous crystalline scale in contact with the water. More than the morphology, the chemical compositions of both layers are different. This duplex structure results from a mixed growth mechanism: an anionic growth to develop the inner oxide and a cationic diffusion followed by a dissolution-precipitation process to form the outer one. Dynamic experiments at 70 C and corrosion kinetics measurements have demonstrated that the oxide growth process is controlled by a diffusion step associated to a dissolution/precipitation process. A corrosion mechanism of the AlFeNi alloy in aqueous media has been proposed. Then post-irradiation exams performed on irradiated fuel plates were used to investigate the effects of the irradiation on the corrosion behaviour in the reactor core. (author)

  4. An investigation of the corrosion of WC-Co cermets in CN--containing aqueous solutions. Part II: Synchrotron-based high lateral-resolution XPS study

    International Nuclear Information System (INIS)

    In the literature on the corrosion behaviour of WC-Co hardmetal grades, it has been pointed out that - typically - corrosion resistance in several aqueous environments relies on the formation of pseudo-passivating layers on top of the two-phase material. So far, no detailed space-dependent study has been performed of the local structure and chemistry of such peculiar corrosion-product layers. In this paper, we propose a detailed chemical analysis - performed with a remarkably advanced synchrotron-based photo-electron microscope - of samples whose electrochemical (CV) and spectroelectrochemical (in situ SFG and ERS) characterisation has been published in a companion paper [B. Bozzini, B. Busson, G.P. De Gaudenzi, L. D'Urzo, C. Mele, A. Tadjeddine, Corros. Sci. 49 (2007) 2392-2405].

  5. An investigation of the corrosion of WC-Co cermets in CN{sup -}-containing aqueous solutions. Part II: Synchrotron-based high lateral-resolution XPS study

    Energy Technology Data Exchange (ETDEWEB)

    Bozzini, Benedetto [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, via Monteroni, 73100 Lecce (Italy)], E-mail: benedetto.bozzini@unile.it; Dalmiglio, Matteo [Sincrotrone Trieste SCpA, SS14-Km163.5 in Area Science Park, I-34012 Trieste (Italy); De Gaudenzi, Gian Pietro [Films S.p.a., v. Megolo 2, I-28877, Anzola d' Ossola (Italy); D' Urzo, Lucia [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, via Monteroni, 73100 Lecce (Italy); Gregoratti, Luca [Sincrotrone Trieste SCpA, SS14-Km163.5 in Area Science Park, I-34012 Trieste (Italy)

    2009-08-15

    In the literature on the corrosion behaviour of WC-Co hardmetal grades, it has been pointed out that - typically - corrosion resistance in several aqueous environments relies on the formation of pseudo-passivating layers on top of the two-phase material. So far, no detailed space-dependent study has been performed of the local structure and chemistry of such peculiar corrosion-product layers. In this paper, we propose a detailed chemical analysis - performed with a remarkably advanced synchrotron-based photo-electron microscope - of samples whose electrochemical (CV) and spectroelectrochemical (in situ SFG and ERS) characterisation has been published in a companion paper [B. Bozzini, B. Busson, G.P. De Gaudenzi, L. D'Urzo, C. Mele, A. Tadjeddine, Corros. Sci. 49 (2007) 2392-2405].

  6. Electrochemical corrosion behavior of AZ91D alloy in ethylene glycol

    International Nuclear Information System (INIS)

    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.

  7. Microstructure and corrosion behavior of multipass gas tungsten arc welded 304L stainless steel

    International Nuclear Information System (INIS)

    Highlights: • Multipass gas tungsten arc welding of 304L stainless steel was successfully done. • All welds were austenitic with the presence of a small amount of δ-ferrite. • The morphology of δ-ferrite showed the lathy and skeletal δ-ferrite in the welds. • Hardness and corrosion resistance were improved by multipass welding. • The best joint properties were obtained after three passes welding. - Abstract: The purpose of this study was to discuss the effect of single pass and multipass (double and triple pass) gas tungsten arc welding (GTAW) on microstructure, hardness and corrosion behavior of 304L stainless steel. In this investigation, 308 stainless steel filler metal was used. Microstructures and hardness of the weldments were investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD) and Vickers microhardness (HV0.5). A ferritescope was also used in the non-destructive evaluation to observe the ferrite content on the weldments. Corrosion behavior of weldments in 1 M H2SO4 solution at 25 ± 1 °C was investigated using potentiodynamic polarization and immersion tests. Results indicated that the microstructure of fusion zones exhibited dendritic structure contained lathy and skeletal δ-ferrite. The contents of δ-ferrite in the weld zone increased by increasing the number of passes. Therefore, as the number of passes increased, the hardness and corrosion resistance increased

  8. Corrosion fatigue behavior of fastening hole structure and virtual crack propagation tests

    Institute of Scientific and Technical Information of China (English)

    Youhong Zhang; Xinlong Chang; Guozhi Lv; Hui Wang; Zhong Li; Yueliang Cheng

    2008-01-01

    The fatigue crack propagation behavior of the LY12CZ aluminum alloy fastener involving a central hole in air or in 3.5wt% NaC1 solution was investigated. The experimental results indicated that the corrosion fatigue crack growth rate decreased with the increasing loading frequency, and in a corrosive environment, the crack growth rate was slightly larger than that in air.Based on the experimental results, the virtual corrosion fatigue crack propagation tests were investigated and the stochastic process method and the AFGROW simulation method were presented. The normal process and lognormal process were considered for the stochastic process method based on the numerically fitted Paris equation. The distribution of crack size and the corresponding prob-abilistic model of crack length distribution for a given number of cycles can be found by integrating the stochastic process over time.Using the AFGROW software, the virtual simulation was carried out to analyze the corrosion fatigue crack growth behavior and the predicted crack growth curve was in good agreement with the experimental results.

  9. Corrosion Behavior of Surface-treated Ferritic/Martensitic Steel in Liquid Sodium Environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, JeongHyeon; Lee, Jung Ki; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of); Shin, Sang Hun [KAERI, Daejeon (Korea, Republic of)

    2015-10-15

    Their compatibility with sodium is one of issues especially dissolution, chemical reaction, and carbon transfer with impurities, which degraded the mechanical properties. The compatibility of cladding and structural materials with sodium has to be carefully investigated, as sodium could promote corrosion of cladding and structural materials in two ways. One is produced by the dissolution of alloy constituents into the sodium, and the other is produced through a chemical reaction with impurities (especially oxygen and carbon) in the sodium environment. Gr.92 is known as compatible in sodium environment because this steel possesses excellent properties. For instance, Gr.92 has high creep and tensile strength, low thermal expansion coefficient. In the Ultra-long Cycle Fast Reactor (UCFR) which is developed in UNIST, however, cladding is exposed long-term in high temperature liquid sodium environment. So, it is very important to investigate the corrosion-related behavior such as surface corrosion rate, carburization, decarburization and mechanical properties for its operation time. In this study, as-received and surface-treated Gr.92 specimen in the oxygen-saturated liquid sodium were examined at high temperature for 300h. The impedance results reveal the information for the corrosion behavior in liquid sodium. Also, microstructure results reveal the information for the maintenance of coating and role of coating.

  10. 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.

  11. The corrosion behavior of Cr-(C,N) PVD hard coatings deposited on various substrates

    International Nuclear Information System (INIS)

    A comparison was made between the electrochemical corrosion behavior of chromium carbonitride (Cr-(C,N)) and chromium nitride (Cr-N) coatings produced by evaporation in a thermionic-arc ion-plating apparatus at 450 deg. C. These coatings were deposited on substrates in the form of discs of mild-steel (CK 45) and stainless-steel (SS 304). Potentiodynamic polarization tests, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) were the techniques used to characterize the corrosion behavior. The potentiodynamic tests revealed the current density versus potential for the coated and uncoated substrates and the difference in their corrosion potentials (Ecorr). In all cases the Ecorr shifted to a more positive potential after the coatings were applied. The electrochemical impedance spectroscopy measurements as a function of immersion time were carried out in a 0.5 M NaCl solution at the Ecorr. The corrosion properties, lower current density, and higher polarization resistance were found to be two to six times better than the uncoated substrate for the Cr-(C,N) coatings and two orders of magnitude better for the Cr-N coatings

  12. Effect of aging on mechanical properties and localized corrosion behaviors of Al-Cu-Li alloy

    Institute of Scientific and Technical Information of China (English)

    JIANG Na; LI Jin-feng; ZHENG Zi-qiao; WEI Xiu-yu; LI Yan-fen

    2005-01-01

    The effects of aging on mechanical properties,intergranular corrosion and exfoliation corrosion behaviors of a 2197 type A1-Li alloy were investigated,and the mechanisms were studied through microstructure observation and electrochemical measurement of simulated bulk phase.The main strengthening precipitates of the alloy aged at175 ℃ and 160 ℃ are δ' and T1.T1 precipitation in the alloy aged at 160 ℃ is delayed,which results in its slower age strengthening and over-aging behavior than the alloy aged at 175 ℃.Meanwhile,aging temperature of 160 ℃causes more uniform distribution and finer size of T1,resulting in its better strengthening effect.As aging time and aging temperature are increased,the size of T1 at grain boundaries and the width of PFZ along grain boundaries are increased,leading to an increase in the susceptibility to intergranular corrosion and exfoliation corrosion.It is suggested that better comprehensive properties can be obtained when the alloy is aged at 160 ℃.

  13. Transgranular stress corrosion cracking of X-80 and X-52 pipeline steels in dilute aqueous solution with near-neutral pH

    Energy Technology Data Exchange (ETDEWEB)

    Gu, B.; Yu, W.Z.; Mao, X. [Univ. of Calgary, Alberta (Canada). Dept. of Mechanical Engineering; Luo, J.L. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical and Materials Engineering

    1999-03-01

    Slow strain rate tests (SSRT) and fractographic examination of X-80 and X-52 pipeline steels showed transgranular stress corrosion cracking (TGSCC) could occur in a dilute aqueous solution with near-neutral pH. SCC intensity increased as the applied electrochemical potential and strain rates decreased. Hydrogen precharging or addition of carbon dioxide (CO{sub 2}) facilitated the process of SCC, suggesting that dissolution and hydrogen ingress were involved in the cracking process.

  14. GILDES model studies of aqueous chemistry. 5: Initial SO{sub 2}-induced atmospheric corrosion of nickel

    Energy Technology Data Exchange (ETDEWEB)

    Tidblad, J.; Graedel, T.E. [Lucent Technologies, Murray Hill, NJ (United States). Bell Labs.

    1997-08-01

    The authors report in this paper the first theoretical treatment of kinetic and equilibrium chemical processes of the atmospheric corrosion of nickel performed with the multiregime GILDES model. The formulation for exposure of nickel to sulfur dioxide in humidified air involves 67 reactions for 35 species and includes a representation of the protective properties of corrosion products. Two protective mechanisms are investigated: transport through the corrosion products of corrosive agents and blocking of the active surface area. The latter appears to dominate. Results for corrosion products and corrosion rate are compared with those for laboratory exposures at 210 ppb SO{sub 2}, and agreement is excellent.

  15. Corrosion behavior of steels in liquid lead-bismuth with low oxygen concentrations

    International Nuclear Information System (INIS)

    Corrosion tests in pots for various steels were conducted in liquid lead-bismuth with low oxygen concentrations to elucidate corrosion behavior of steels in liquid lead-bismuth that is expected to be used for accelerator driven systems and fast reactors. The corrosion tests were performed for 3000 h under the condition of an oxygen concentration of 5x10-8 wt% at 450degC and an oxygen concentration of 3x10-9 wt% at 550degC, respectively. At 450degC, the corrosion rate of 316SS was 0.23 mm/y while it was below 0.1 mm/y for F82H, Mod.9Cr-1Mo steel, JPCA(14Cr-16Ni-2Mo), 410SS, 430SS, 2.25Cr-1Mo steel, pure iron and SX(18Cr-19Ni-5Si). Dissolution of Ni and Cr, and penetration of Pb and Bi occurred in 316SS and JPCA. Dissolution of iron and grain boundary corrosion were observed in pure iron and 2.25Cr-1Mo steel, respectively. At 550degC, the corrosion rate of 316SS reached 1.02mm/y and the corrosion rates of F82H, Mod.9Cr-1Mo steel, JPCA, 410SS, 2.25Cr-1Mo steel and pure iron were in the range between 0.1 and 1 mm/y. It was lower than 0.1 mm/y for 430SS and SX. Significant dissolution attach occurs for pure iron. Grain boundary corrosion and detachment of grains were observed in ferritic/martensitic steels. Ferritization and penetration of Pb and Bi occur over a wide range in 316SS and JPCA. It is difficult to prevent the grain boundary corrosion caused by Pb and Bi, and selective dissolution of Ni and Cr by using oxide films such as (Mn, Cr)-O and (Mn, Cr, Fe)-O formed under the condition of the low oxygen concentration at 550degC. (author)

  16. Corrosiveness of wet residential building thermal insulation---Mechanisms and evaluation of electrochemical methods for assessing corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Stansbury, E.E. (Stansbury (E.E.), Knoxville, TN (United States))

    1991-10-01

    An evaluation has been made of the corrosiveness of selected wet residential building thermal insulation materials in contact with low carbon steel. Investigations were conducted both in wet insulations and in filtered leachates from insulations derived from thirteen cellulosic, three mineral fiber and four foam products. Potentiodynamic polarization measurements are reported from which the overall corrosion response was assessed and then the techniques of Tafel and polarization resistance analysis applied to estimate corrosion rates. Corrosion rates were also estimated electrochemically using a direct reading instrument which performs the rate calculation based on the polarization resistance principle. Direct determinations of corrosion rate were based on weight loss measurements.

  17. 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...

  18. Corrosion Inhibition of Aluminum in 0.5 M HCl by Garlic aqueous extract

    Directory of Open Access Journals (Sweden)

    Saedah R. Al-Mhyawi

    2014-06-01

    Full Text Available The inhibition efficiency of extract of Garlic on aluminium in hydrochloric acid solutions has been evaluated by weight loss techniques. Values of inhibition efficiency obtained are dependent upon the concentration of inhibitor and temperature. Generally, inhibition was found to increase with inhibitor concentration, half-life, activation energy but decrease with temperature and first-order rate constant at the temperatures studied. Physical adsorption mechanism has been proposed for the inhibition and Langmuir , Temkin adsorption isotherm was obeyed. Garlic is an inhibitor of aluminium corrosion in 0.5 M hydrochloric acid solution.The values of standard free energy of adsorption suggest that the adsorption of inhibitor on aluminium surface occurred by physisorption mechanism. the negative sign of the Free Energy of adsorption indicates that the adsorption of the inhibitors on the aluminum surface was a spontaneous process.the negative values of enthalpy of adsorption (ΔH suggest that the chemical reaction involved in the adsorption of the inhibitors on the metal surface is an exothermic process, hence increase in the reaction temperature of the medium will decrease the inhibition efficiency.

  19. Chromium in aqueous nitrate plutonium process streams: Corrosion of 316 stainless steel and chromium speciation

    International Nuclear Information System (INIS)

    This study was undertaken to determine if chromium(+6) could exist in plutonium process solutions under normal operating conditions. Four individual reactions were studied: the rate of dissolution of stainless steel, which is the principal source of chromium in process solutions; the rate of oxidation of chromium(+3) to chromium(+6) by nitric acid; and the reduction of chromium(+6) back to chromium(+3) by reaction with stainless steel and with oxalic acid. The stainless steel corrosion rate was found to increase with increasing nitric acid concentration, increasing hydrofluoric acid concentration, and increasing temperature. Oxidation of chromium(+3) to chromium(+6) was negligible at room temperature and only became significant in hot concentrated nitric acid. The rate of reduction of chromium(+6) back to chromium(+3) by reaction with stainless steel or oxalic acid was found to be much greater than the rate of the reverse oxidation reaction. Based on these findings and taking into account normal operating conditions, it was determined that although there would be considerable chromium in plutonium process streams it would rarely be found in the (+6) oxidation state and would not exist in the (+6) state in the final process waste solutions

  20. Microstructure analysis and corrosion behavior of biodegradable Mg-Ca implant alloys

    International Nuclear Information System (INIS)

    Highlights: → Evaluation of corrosion mechanism and solidification behavior of Mg-xCa. → Microstructure of Mg-xCa alloys were characterized by XRD, OM, SEM and EDS. → Thermal analysis of alloys was carried out by computer aided cooling curve analysis. → The addition of Ca content increase Mg2Ca lead to increasing corrosion rate. -- Abstract: The calcium content in binary Mg-xCa alloys affects the microstructure, corrosion and solidification behavior of the alloys. In this study, binary Mg-xCa alloys with various Ca contents from 0.5 to 10 wt.% were produced by casting process. Microstructural evolutions were characterized by optical microscopy, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. Solidification behavior was assessed via two thermocouple thermal analysis method. The corrosion resistance was examined in vitro by potentiodynamic polarization and immersion test in Kokubo solution at room temperature. The results revealed that the grain size and dendrite cell size decreased significantly with rising Ca content, whilst the content of Mg2Ca intermetallic phase in grain boundaries increased with increasing Ca content. Potentiodynamic polarization tests in simulated body fluid (SBF) indicated that corrosion rates of Mg-xCa alloy increased significantly with rising Ca content. Immersion tests in Kokubo solution also showed that dissolution rate of Mg-xCa alloy increased with increasing Mg2Ca content which lead to an increase in pH value. It was observed that corrosion damage in specimens with lower Ca content was more moderate and uniform than higher Ca content. Thermal analysis results showed that the fraction of primary α-Mg at dendrite coherency point (fαDCP) decreased with increasing Ca content but the liquid fraction fL increased causing the rise in eutectic Mg2Ca intermetallic phase in grain boundaries, thus increasing the corrosion rate. Our analyses showed that Mg-0.5Ca alloy is a promising alloy to be

  1. Corrosion Behavior of Electrodepositing Ni/Al2O3 Composite Coatings under the Presence of NaCl Deposit

    Institute of Scientific and Technical Information of China (English)

    Xie Danyang; Liu Lin

    2007-01-01

    The morphology and corrosion behavior of Ni/Al2O3 composite coatings prepared using double-pulsed electrodepositing technique after oxidized under 800℃ NaCl deposit in air environment were analyzed by scanning electrical microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrum (EDS). The results showed that the corrosion of all composite coatings was accelerated under NaCl deposits, and the corrosion products were rather porous with poor adherence to the matrix. Al2)O3 particles in the coatings can refine the grain size and improve the high temperature corrosion resistance of the coatings. Within the test scope, the more Al2O3 particles in the coatings, the lower corrosion rates could be obtained, and the corrosion mechanism was also discussed.

  2. In vitro corrosion behavior and cellular response of thermally oxidized Zr-3Sn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, F.Y.; Wang, B.L.; Qiu, K.J. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Li, H.F. [Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Li, L. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Zheng, Y.F., E-mail: yfzheng@pku.edu.cn [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Han, Y. [State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, Xian 710049 (China)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer A main monoclinic ZrO{sub 2} layer formed on ZrSn alloy after thermal oxidation. Black-Right-Pointing-Pointer Corrosion resistance of ZrSn alloy was improved with thermal oxidation. Black-Right-Pointing-Pointer The oxide layer inhibited the release of the ions into the mediums. Black-Right-Pointing-Pointer Oxidized ZrSn alloy exhibited an excellent in vitro biocompatibility. - Abstract: In this study, ZrSn alloy was thermally oxidized at 600 Degree-Sign C for 3 h and its morphological and structural characteristics, corrosion behavior, ion release and in vitro cytocompatibility were studied to evaluate the feasibility of applying it as dental implant. After oxidation, a dense black oxide layer formed on ZrSn alloy surface, which consisted of predominant monoclinic zirconia and a few non-stoichiometric oxides. The scratching and water contact angle test results demonstrated that the oxide layer exhibited good adhesion strength and similar hydrophilicity to zirconia. The oxidized ZrSn alloy showed higher corrosion resistance, as indicated by far lower corrosion current density and passive current density compared to pure Ti and untreated ZrSn alloy in artificial saliva with and without H{sub 2}O{sub 2}. The amount of ions released from the oxidized ZrSn alloy was much lower than that dissolved from pure Ti in simulated corrosive oral mediums. Moreover, the oxidized ZrSn alloy did not present any significant toxic effect to both osteoblast-like cells and fibroblast cells, and osteoblast-like cells could adhere well onto the surface and exhibited a good proliferative pattern. The combination of improved surface properties, superior corrosion resistance and good biocompatibility made the oxidized ZrSn alloy promising for oral implantology application.

  3. Corrosion behavior of the tube - tubular plate joint zone in the presence of sediments

    International Nuclear Information System (INIS)

    The corrosion is a very important problem which concerns the safe operation of steam generators. The predominant part of corrosion problems is related to the local concentration of aggressive species and/or to the impurities from the slow-flow regions, like those created by cracks in tube - tubular plate joint zones. The consequences of such local concentrations are very important and as such entail interest in the design and utilization of steam generators. This study presents the results of the corrosion tests performed under specific operation conditions of the secondary circuit in NPP (temperature, 260 o C; pressure, 5.1 MPa) on a crack simulating device made of carbon steel SA 508 cl.2 (forming the tubular plate) and Incoloy-800 (forming the tubes). The chemical medium of these tests was the following: solution of NaCl, 25g/l (pH=10.5); solution of NaCl, 50 g/l (pH=10.5); solution of NaCl, 75g/l (pH=10.5); solution of NaCl, 75g/l + solution of Na2 SO4, 10 g/l (pH=10.5). The behavior of these two materials to corrosion was studied by metallographic investigations. The results are presented as microphotographs evidencing the occurrence of pitting corrosion first on material of the tubular plate, in the presence of medium particularly aggressive and on the material of the tubes. The aim of this study is to establish the corrosion mechanism as well as the formation of the oxide layer on the carbon steel in crack simulating devices. (authors)

  4. Corrosion behavior of Ni-based structural materials for electrolytic reduction in lithium molten salt

    Science.gov (United States)

    Cho, Soo Haeng; Park, Sung Bin; Lee, Jong Hyeon; Hur, Jin Mok; Lee, Han Soo

    2011-05-01

    In this study, the corrosion behavior of new Ni-based structural materials was studied for electrolytic reduction after exposure to LiCl-Li 2O molten salt at 650 °C for 24-216 h under an oxidizing atmosphere. The new alloys with Ni, Cr, Al, Si, and Nb as the major components were melted at 1700 °C under an inert atmosphere. The melt was poured into a preheated metallic mold to prepare an as-cast alloy. The corrosion products and fine structures of the corroded specimens were characterized by scanning electron microscope (SEM), Energy Dispersive X-ray Spectroscope (EDS), and X-ray diffraction (XRD). The corrosion products of as cast and heat treated low Si/high Ti alloys were Cr 2O 3, NiCr 2O 4, Ni, NiO, and (Al,Nb,Ti)O 2; those of as cast and heat treated high Si/low Ti alloys were Cr 2O 3, NiCr 2O 4, Ni, and NiO. The corrosion layers of as cast and heat treated low Si/high Ti alloys were continuous and dense. However, those of as cast and heat treated high Si/low Ti alloys were discontinuous and cracked. Heat treated low Si/high Ti alloy showed the highest corrosion resistance among the examined alloys. The superior corrosion resistance of the heat treated low Si/high Ti alloy was attributed to the addition of an appropriate amount of Si, and the metallurgical evaluations were performed systematically.

  5. Effect of trace Sn on corrosion behaviors of high voltage anode aluminum foil

    Institute of Scientific and Technical Information of China (English)

    SONG Jing-bo; MAO Wei-min; YANG Hong; FENG Hui-ping

    2008-01-01

    The cube texture and the surface corrosion structure of aluminum anode foil for high voltage electrolytic capacitor containing trace Sn were investigated based on quantitative texture analysis and microstructure observation under SEM. High volume fraction of cube texture over 95% and obviously higher specific capacity are obtained in the foils with less than 0.002% Sn. It is indicated that the corrosion behavior of trace Sn on aluminum surface is similar with that of Pb. Higher content of Sn over 0.002% reduces the cube texture component and therefore the specific capacity. Sn, as an eco-friendly microelement, can be applied to replace Pb in improving the homogenous pitting behaviors of high voltage aluminum foils.

  6. Environmental factors affecting the corrosion behavior of reinforcing steel III. Measurement of pitting corrosion currents of steel in Ca(OH)2 solutions under natural corrosion conditions

    International Nuclear Information System (INIS)

    Using a simple electrolytic cell, the pitting corrosion current of reinforcing steel is measured in Ca(OH)2 solutions in presence of chloride and sulfate as aggressive ions. Pitting corrosion current starts to flow after an induction period which depends on the concentration of both the aggressive and the passivating anions. The pitting corrosion current densities reach steady-state values which depend also on the type and concentration of the corrosive and passivating anions. The corrosive action of the aggressive species decreased in the order: SO42- > Cl-. Corrosion of the steel is found to be governed by a single electron transfer reaction. Raising the temperature decreases the induction period associated with pit initiation and increases the corrosion current associated with pit propagation. From Arrhenius plots, the activation energies for both pit initiation and pit propagation in presence of chloride and sulfate ions are calculated.

  7. Preparation and corrosion behavior evaluation of amalgam/titania nano composite

    OpenAIRE

    Neda Bahremandi Tolou; Mohammadhossein Fathi; Ahmad Monshi; Vajihesadat Mortazavi; Farzaneh Shirani

    2011-01-01

    Background: Many attempts have been performed and continued for improvement of dental amalgam properties during last decades. The aim of present research was fabrication and characterization of amalgam/titania nano composite and evaluation of its corrosion behavior. Materials and Methods: In this experimental research, nano particles of titania were added to initial amalgam alloy powder and then, dental amalgam was prepared. In order to investigate the effect of nano particle amounts on p...

  8. Corrosion Behavior of Duplex Stainless Steels in Acidic-Chloride Solutions Studied with Micrometer Resolution

    OpenAIRE

    Femenia, Marc

    2003-01-01

    The local corrosion behavior of duplex stainless steel (DSS)is affected by a wide variety of factors. Localized corrosionof DSS frequently starts at micrometer scale inclusions orprecipitates, which are often segregated in theaustenite-ferrite boundary regions. Moreover, due to thepartitioning of the key alloying elements of ferrite (Cr andMo) and austenite (N and Ni), the local interactions betweenthe phases must also be considered. The aim of this doctoral study was to increase the knowledg...

  9. Corrosion behavior of silver-palladium dental casting alloys in artificial saliva

    Science.gov (United States)

    Krajewski, Katherine Mary

    Ag-Pd dental casting alloys have been used as alternatives to high gold alloys in restorative dentistry since the 1980s. These alloys exhibited mechanical properties superior to gold alloys and excellent adherence to porcelain in porcelain fused to metal (PFM) restorations, such as dental crowns. However, later increases in the price of palladium along with concerns regarding possible allergic reactions and palladium's cytotoxicity have limited the use of these alloys. Evaluation of the biocompatibility concern requires a better understanding of the interaction of Ag-Pd alloys with the oral environment, and the cost problem would be lessened if the palladium content could be reduced without lowering the corrosion resistance. Previous studies have shown differences in the corrosion behavior between Pd-rich and Ag-rich alloys, but the mechanisms of the two behaviors are not well understood. The purpose of this study was to characterize the electrochemical behavior of binary Ag-Pd alloys under conditions simulating the exposure in the oral cavity. Electrochemical measurements, surface and solution analysis were performed with alloy composition, electrolyte composition, and exposure time as variables. Results showed the corrosion behavior for all alloys was governed by the formation of an insoluble thiocyanate salt combined with selective dissolution of Ag for the Pd-rich alloys. The tendency to form thiocyanate was found to dominate over the tendency to form chloride, the formation of which was suggested in other studies. The electrode behavior has been explained on the basis of the theory of behavior of electrodes of the second kind. The difference in behavior of Ag-rich and Pd-rich alloys has been related to the difference in the solubility of the salts and difference in bonding of thiocyanate with Pd and Ag.

  10. 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.

  11. Comparative study on the corrosion behavior of milled and unmilled magnesium by electrochemical impedance spectroscopy

    International Nuclear Information System (INIS)

    The corrosion behavior of milled Mg prepared by high-energy ball milling for 10 h has been investigated in alkaline solutions by electrochemical impedance spectroscopy and compared with that of unmilled Mg. X-ray powder diffraction indicates a crystallite size of 34 nm for the milled Mg compared to >100 nm for the unmilled powder. Chemical analyses show no significant iron contamination in milled Mg powder, indicating the absence of tools erosion during the milling procedure. In contrast, significant MgO enrichment in the milled powder is observed (6.5 wt.% after 10 h milling compared to 1.0 wt.% before milling). The oxygen contamination is mainly attributed to the powder oxidation occurring during milling. From XPS analyses, no MgO enrichment is detected on milled Mg electrode surface, confirming that MgO is dispersed homogeneously in the bulk of the material rather than to segregate on its surface. Electrochemical impedance spectroscopy demonstrates clearly the better corrosion resistance of milled Mg compared to unmilled Mg in passive conditions (KOH solution, pH=14) and in more active corrosion conditions (borate solution, pH=8.4). This is illustrated by a nobler corrosion potential and by a significant increase of the interfacial resistance related to the film and charge-transfer reaction. Moreover, the variation of the different electrochemical parameters (corrosion potential, interfacial resistance and capacitance) with immersion time is less accentuated and tends more rapidly to a steady state with milled Mg, suggesting an enhancement of the Mg(OH)2 formation kinetic. The origin of the distinctive passivation behavior of ball-milled Mg is discussed

  12. Corrosion Behavior of Ti-Based In Situ Dendrite-Reinforced Metallic Glass Matrix Composites in Various Solutions

    Science.gov (United States)

    Yang, F.; Tian, H. F.; Lan, A. D.; Zhou, H. F.; Wang, B. C.; Yang, H. J.; Qiao, J. W.

    2015-06-01

    The electrochemical corrosion behaviors of Ti40Zr24V12Cu5Be19 in situ dendrite-reinforced metallic glass matrix composites (MGMCs) were investigated by potentiodynamic polarization experiments and electrochemical impedance spectroscopy in acidic, salty, and alkaline solutions. Ti40Zr24V12Cu5Be19 in situ dendrite-reinforced MGMCs have an impressive corrosion resistance in strong acidic environment, while their performance was not so great in strong alkaline environment. Further immersion test in same solutions revealed similar chemical corrosion behaviors. XRD and SEM examinations were conducted to check the structure and surface modification of the material during the corrosion process. EDS test indicated that the amorphous matrices, which show excellent corrosion resistance, have a considerable composition variation from its crystalline dendrites counterpart.

  13. Corrosion behavior of aluminum alloys in Na2SO4 solution using the scanning electrochemical microscopy technique

    Institute of Scientific and Technical Information of China (English)

    He-rong Zhou; Xiao-gang Li; Chao-fang Dong; Kui Xiao; Tai Li

    2009-01-01

    The corrosion behavior of aluminum alloys 1060 and 2A12 in a 10 mM Na2SO4+5 mM KI solution was investigated by scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM).The potential topography and corrosion morphology results show that the potential of the sample surface over the same area changes with the increase of immersion time.The corrosion area becomes large,and the potential becomes more negative.The corrosion potential of the 2A12 alloy surface is lower than that of 1060 aluminum,and 2A12 alloy becomes easily corrosive.This is the reason that preferential dissolution in the boundary region of some intermetaUic particles (IMPs) occurs and different dissolution behaviors are associated with different types of IMPs because of different potentials.

  14. Assessing the effect of cement-steel interface on well casing corrosion in aqueous CO2 environments

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jiabin [Los Alamos National Laboratory; Carey, James W [Los Alamos National Laboratory; Zhang, Jinsuo [Los Alamos National Laboratory

    2010-01-01

    CO{sub 2} leakage is a critical safety concern for geologic storage. In wellbore environments, important leakage paths include the rock-cement and cement-casing interfaces. If the cement-casing interface is filled with escaping CO{sub 2}, the well casing directly contacts the CO{sub 2}. This can cause severe corrosion in the presence of water. This paper studies the effect of steel-cement interface gaps, ranging from 1 mm to 0 um, on casing corrosion. Corrosion kinetics were measured employing electrochemical techniques including linear polarization resistance, open circuit potential and electrochemical impedance spectroscopy. The experimental results showed that the corrosion of steel is not significant where the gap between steel and cement is small ({le} 100 {micro}m). Corrosion rates are controlled by the diffusion of corrosive species (H{sub 2}CO{sub 3} and H{sup +}) along the interface. In contrast, steel corrosion is severe in a broad gap where the corrosion process is limited only by the reaction kinetics of steel and corrosive species. The threshold leading to severe corrosion in terms of the cement-steel interface size (100 {micro}m) was determined. Our research clarifies a corrosion scenario at the cement-steel interface. Casing steel corrosion is initiated when attacked by corrosive species at the cement-steel interface. For relatively tight interfaces, this results in a slow thinning of the casing and expansion of the interface width. If the gap increases beyond the critical threshold size, the corrosion rate increases significantly, and a potentially damaging cycle of corrosion and interface expansion is developed.

  15. Corrosion behavior of cold-worked austenitic stainless steels in liquid lead–bismuth eutectic

    Energy Technology Data Exchange (ETDEWEB)

    Kurata, Yuji, E-mail: kurata.yuji@jaea.go.jp

    2014-05-01

    Highlights: • Austenitic stainless steels cold-worked up to 50% were exposed to lead–bismuth. • Lead–bismuth with the low oxygen concentration caused deep ferritization at 550 °C. • Ferritization also occurred at 550 °C during 3000 h under the high oxygen condition. • Cold working accelerated ferritization and Pb–Bi penetration without a protective film. • Attention should be also focused on the cold-working effect on corrosion behavior. - Abstract: The effect of cold working on the corrosion behavior of austenitic stainless steels in liquid lead–bismuth eutectic (LBE) was studied to develop accelerator-driven systems for the transmutation of long-lived radioactive wastes and lead–bismuth cooled fast reactors. Corrosion tests on solution-treated, 20% cold-worked and 50% cold-worked 316SS and JPCA (15Cr–15Ni–Ti) were conducted in oxygen-controlled LBE. Slight ferritization caused by Ni dissolution and Pb–Bi penetration were observed for all specimens in the corrosion test conducted at 500 °C for 1000 h in liquid LBE with an intermediate oxygen concentration (1.4 × 10{sup −7} wt.%). In the corrosion test performed at 550 °C for 1000 h in liquid LBE with a low oxygen concentration (4.2 × 10{sup −9} wt.%), the depth of the ferritization of 316SS and JPCA increased with the extent of cold working. Only oxidation was observed in the corrosion test that was performed at 550 °C for 1000 h in liquid LBE with a high oxygen concentration (approximately 10{sup −5} wt.%). Cold working accelerated the formation of the double layer oxide and increased the thickness of the oxide layer slightly. In contrast, the ferritization accompanied by Pb–Bi penetration was widely observed with oxidation for all specimens corrosion tested at 550 °C for 3000 h under the high-oxygen condition. Cold working increased the depth of the ferritization of 316SS and JPCA. It is considered that cold working accelerated the ferritization and Pb–Bi penetration

  16. Effects of Cl- and SO2-4 Ions on Corrosion Behavior of X70 Steel

    Institute of Scientific and Technical Information of China (English)

    Junwei WU; Xiaogang LI; Cuiwei DU; Song WANG; Yiquan SONG

    2005-01-01

    Corrosion behaviors of X70 steel were studied by means of electrochemical experiments and morphology observation.First, through potentiodynamic polarization in solution of various Cl- ions concentration, it was found that Epit began to appear in solution of Cl- concentration above 0.1 mol/L, and there was a critical point of Cl- concentration between 0.05 mol/L and 0.1 mol/L, below which the extent of pitting and general corrosion were trivial, while in solution of Cl- concentration above 0.1 mol/L, general and pitting corrosion became greater as the increasing of Cl- concentration. All of them were confirmed by the SEM observations after anodic polarization. Second, via the potentiodynamic polarization curves of X70 steel in 0.5 mol/L Cl- solution with 0, 0.05, 0.5 and 1 mol/L SO42-ions, it was found SO42- ions were able to inhibit corrosion aroused from Cl- ions, accordingly a model was set up to describe the process. In addition, to further explore the inhibited effect of SO42- ions, EIS was used in solutions of different Cl- and SO42- concentrations, the results revealed that the e(ectrochemical resistance has a relation with the [SO42-]/[Cl-], that was, the bigger the value of [SO42-]/[Cl-], the greater the electrochemical resistance.

  17. Formation and corrosion behavior of glassy Ni-Nb-Ti-Zr-Co(-Cu) alloys

    International Nuclear Information System (INIS)

    Bulk glassy Ni55Nb20Ti10Zr8Co7 alloy with a critical diameter of 2 mm was synthesized by copper-mold casting and the glass transition temperature, crystallization temperature and supercooled liquid region are 858 K, 911 K and 52 K, respectively. High corrosion resistance in 1N HCl and H2SO4 solutions was recognized for the glassy alloys Ni55Nb20Ti10Zr8Co7 together with Ni53Nb20Ti10Zr8Co6Cu3 which possesses higher glass-forming ability. They are spontaneously passivated with low passive current densities of the order of 10-2 A/m2 and their corrosion rate was less than 10-3 mm/year in the solutions. A small amount addition of Cu (3 at.%) in the Ni-Nb-Ti-Zr-Co glassy alloy system has little effect on corrosion behavior and surface film composition. Niobium-rich passive films form on the glassy Ni-Nb-Ti-Zr-Co(-Cu) alloys, which could be responsible for the high corrosion resistance

  18. Microstructure and corrosion behavior of electroless deposited Ni-P/CeO2 coating

    Institute of Scientific and Technical Information of China (English)

    Hui Ming Jin; Shi Hang Jiang; Lin Nan Zhang

    2008-01-01

    Electroless Ni-P/nano-CeO2 composite coating was prepared in acidic condition,and its microstructure and corrosive property were compared with its CeO2-free counterpart.Scanning electronic microscopy (SEM) and X-ray diffraction (XRD) spectrometer were used to examine surface morphology and structure of the as-plated coating.Differential scanning calorimeter (DSC) and transmission electronic microscopy (TEM) were used to study the coating's phase change at high temperature.The coating's corrosive behavior in 3%NaCI + 5%H2SO4 solution was also investigated.The results showed that Ni-P coating had partial amorphous structure mixed with nano-crystals,while the Ni-P/CeO2 coating had perfect amorphous structure.In high-temperature condition,Ni3P precipitation and Ni crystallization took place in both coatings but at different temperatures,while the Ni-P/CeO2 coating had sintered phase of NiCe2O4 spinels.The anti-corrosion property was better in the CeO2-containing coating,and this was due to its less liability to undergo local-cell corrosion than its CeO2-free counterpart.Ni-P/CeO2 coating's pure amorphous structure was the result of Ni's hindered crystal-typed deposition and P's promoted deposition.

  19. Corrosion Behavior of the Stressed Sensitized Austenitic Stainless Steels of High Nitrogen Content in Seawater

    Directory of Open Access Journals (Sweden)

    A. Almubarak

    2013-01-01

    Full Text Available The purpose of this paper is to study the effect of high nitrogen content on corrosion behavior of austenitic stainless steels in seawater under severe conditions such as tensile stresses and existence of sensitization in the structure. A constant tensile stress has been applied to sensitized specimens types 304, 316L, 304LN, 304NH, and 316NH stainless steels. Microstructure investigation revealed various degrees of stress corrosion cracking. SCC was severe in type 304, moderate in types 316L and 304LN, and very slight in types 304NH and 316NH. The electrochemical polarization curves showed an obvious second current peak for the sensitized alloys which indicated the existence of second phase in the structure and the presence of intergranular stress corrosion cracking. EPR test provided a rapid and efficient nondestructive testing method for showing passivity, degree of sensitization and determining IGSCC for stainless steels in seawater. A significant conclusion was obtained that austenitic stainless steels of high nitrogen content corrode at a much slower rate increase pitting resistance and offer an excellent resistance to stress corrosion cracking in seawater.

  20. Influence of surface roughness on the corrosion behavior of Alloy 690TT in PWR primary water

    International Nuclear Information System (INIS)

    Highlights: • Surface roughness effect on the corrosion rate of Alloy 690 is provided. • Surface micro-hardness decreased as the roughness value decreased. • Cr-enriched polyhedral oxide particles were formed on the ground surfaces. • Ni-enriched strip-like oxides were formed on the polished surfaces. • Corrosion rate decreased with a decrease in the roughness value. - Abstract: The purpose of this work is to investigate the effect of surface roughness on the corrosion behavior of Alloy 690TT steam generator tube material in simulated primary water at 330 °C. The surface roughness was controlled in the range of 710–25 nm by mechanical grinding and polishing method. Surface hardness gradually decreased with a decrease in the roughness value. Polyhedral oxide particles were formed on the ground surfaces, whereas the mixed oxides of a polyhedral and strip-like type were observed on the polished surface. The corrosion rate decreased by about 64% as the roughness values decreased from 710 to 150 nm. However, no further changes were observed in the range of 150–25 nm

  1. Mechanical properties and corrosion behavior of materials exposed to an experimental, atmospheric fluidized-bed combustor

    International Nuclear Information System (INIS)

    A joint materials test program developed by the Institute for Mining and Minerals Research (IMMR) and the Tennessee Valley Authority (TVA) involved the postexposure mechanical properties and corrosion behavior of candidate structural materials in an experimental, atmospheric fluidized-bed combustor (AFBC). This combustor was operated by Accurex Corporation at Research Triangle Park, North Carolina, under the direction of TVA. The materials studied were Type 304, Type 310, and INCOLOY alloy 800 in the form of disc coupons with and without crevice configurations. Type 304 was also used for mechanical property measurements. The alloys were exposed to the combustor environment at about8400C for approximately 330 hours. The ranking in terms of decreasing weight loss was: (1) Type 304, (2) Type 310, and (3) INCOLOY alloy 800. The presence of tight crevices did not enhance the corrosion rate. In addition, the corrosion rates, based on the weight loss (typically 1 to 6 mpy), indicated that the alloys performed reasonably well when considering materials wastage. However, optical microscopy observations showed intergranular corrosion penetration in INCOLOY alloy 800 and Type 304. The mechanical properties of Type 304 were inferior to the unexposed alloy. A comparison of the data obtained from the combustor-exposed 304ss tensile samples with data from control samples exposed in vacuum to a similar thermal history indicated that the chemistry of the AFBC environment did not play a major role in the observed degradation of the mechanical properties

  2. Preliminary study on electrochemical corrosion behavior of F82H steel

    International Nuclear Information System (INIS)

    A study on the corrosion behavior of F82H steel and the effects of tritium on it using the electrochemical techniques of Tafel extrapolation and anodic polarization has just been started and the preliminary results without the use of tritiated water were introduced in the present report. Using Tafel extraporation, the corrosion rate of F82H steel in 5w% H2SO4/H2O could be estimated as approximately 2 cm year-1, which was approximately 2 orders of magnitude larger than that of SUS 304. In anodic polarization curve, the regions of passivation, passive layer sustention and transpassivation could be observed under the same circumstance as Tafel extrapolation experiment and the quantum of electricity for F82H steel to passivate was approximately 100 C cm-2, which was approximately 3 orders of magnitude larger than that of SUS304. Therefore it was expected that the corrosion rate of F82H steel could far higher than that of SUS304, even though only a preliminary experiments under the highly corrosive circumstance has been performed. (author)

  3. Corrosion behavior of titanium alloy Beta-21S coated with diamond like carbon in Hank's solution

    Science.gov (United States)

    Mohan, L.; Anandan, C.; Grips, V. K. William

    2012-06-01

    Diamond like carbon (DLC) coatings posses high hardness and low friction coefficient and also biocompatible, hence, they are of interest for enhancing the wear and corrosion resistance of bio-implant materials. Beta stabilized titanium alloys are attractive for biomedical applications because of their high specific strength and low modulus. In this work Beta-21S alloy (Ti-15Mo-3Nb-3Al-0.2Si) was implanted with carbon ions by plasma immersion ion implantation using methane and hydrogen gas mixture followed by DLC deposition by plasma enhanced chemical vapour deposition (PECVD). The implanted layers enabled deposition of adherent diamond-like carbon coatings on the titanium alloy which was otherwise not possible. The corrosion behavior of the treated and untreated samples was investigated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies in simulated body fluid (Hank's solution). XPS, micro Raman and EDAX investigation of the samples showed the formation of a thin oxide layer on the treated samples after corrosion experiments. Corrosion resistance of the DLC coated sample is comparable with that of the untreated samples. Electrochemical impedance data of the substrate and implanted samples were fitted with two time constant equivalent circuits and that of DLC coated samples with two-layer model.

  4. Corrosion Behavior of Ultra-high Strength Steel 300M in Different Simulated Marine Environments

    Institute of Scientific and Technical Information of China (English)

    GUO Qiang; LIU Jianhua; YU Mei; LI Songmei

    2016-01-01

    Corrosion behavior of 300M in neutral corrosion environments containing NaCl simulated by total immersion (TI), salt spraying (SS) and periodic immersion (PI), was investigated by surface analysis techniques, corrosion weight-loss method, and electrochemical measurements. In total immersion environment, rust on the steel consisted of a porous outer rust layer with main constituent ofγ-FeOOH, and an inner rust layer of dense Fe3O4 iflm with network broad cracks. In salt spraying environment, outer rust with main composition ofγ-FeOOH/α-FeOOH/Fe3O4 was compact, and inner rust showed dense Fe3O4 iflm. Rust formed by periodic immersion exhibited a compact outer rust layer with constituent ofα-FeOOH/γ-FeOOH/Fe3O4 and an inner rust layer with composition ofα-FeOOH/α-Fe2O3; inner rust showed a ultra-dense iflm adherent to the steel. The corrosion rate showed a rule ofvs(salt spraying)>vti(total immersion)>>vpi(periodic immersion) in 0-240 h, andvss≈vti»vpiin 240-720 h. The rust formed by periodic immersion was dense and compact, with stable electrochemical properties, and had excellent protection on the steel. Humidity and oxygen concentration in all the environments played major roles in rust formation.

  5. Hot corrosion behavior of Yttria and ceria stabilized zirconia thermal barrier coatings

    International Nuclear Information System (INIS)

    Thermal Barrier Coating(TBC) is generally applied to turbine engines in order to protect metallic components from high temperatures, and thus, to increase the combustion efficiency. Most widely used Yttria Stabilized Zirconia(YSZ; ZrO2-8 wt.%Y2O3) have the poor resistance to hot corrosion under the operating conditions of low quality fuel and sea or desert environments. In order to overcome this problem, Ceria Stabilized Zirconia (CSZ; ZrO2-25 wt.%CeO2-2.5 wt.%Y2O3) has been suggested as a new protective materials for the TBC. In this study, duplex type YSZ-and CSZ-TBCs with similar microstructure were fabricated by detonation gun spraying. High temperature corrosion tests of the TBC specimens, on which NaVO3 salt were pasted, were performed at 900 .deg. C. Results showed that CSZ TBCs is more resistant to NaVO3 salt than YSZ TBCs in terms of phase stability and overall damage by salt. Studies in effects of microstructure indicate that YSZ and CSZ TBCs are degraded by different behavior of stabilizer during the tests and microstructure of TBCs, such as pores, micro cracks and splat boundaries, plays an important role in hot corrosion. From the results stepwise microscopic degradation mechanism of zirconia based TBCs by hot corrosion was discussed

  6. Cf Corrosion-fatigue crack growth behavior of piping and reactor pressure vessel steels

    International Nuclear Information System (INIS)

    As test materials, the nuclear-grade steels were selected such as carbon steel 20 (similar to steel C1020) and 22Κ (similar to steels Κ01701 and Κ02401), alloyed steel 15Χ2ΗΜΦΑ (similar to steel Α543), including the metal of the welded joint, as well as stainless steel 08Χ18Η12Τ (similar to steel 321) with the welded joint. The experimental investigations of the regularities of the crack propagation in steels were carried out on two types of specimens: compact tension and flat bending specimens. The report describes special experimental equipment, test methods and results. The experimental complex includes test facilities with the forced circulation and natural circulation loops, as well as 100 degree aqueous medium test facilities using for comparing the results. The effect of basic load variables (load ratio and frequency), temperature (from 80 degree C to 280 degrees) and aqueous medium chemical composition on the nature of fatigue crack propagation was studied. The selection of the aqueous medium was defined by the conventional water-chemistry conditions of WR and WR with due account for the solution pH value and the electrode potential at the propagating crack tip. The comparison is given of the test results with the effective normative specifications. Based on the analysis of test results the generalized characteristics of the corrosion crack resistance of various structural steels are given. (authors)

  7. Aqueous corrosion of borosilicate glasses: experiments, modeling and Monte-Carlo simulations; Alteration par l'eau des verres borosilicates: experiences, modelisation et simulations Monte-Carlo

    Energy Technology Data Exchange (ETDEWEB)

    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

  8. 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)

    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

  9. 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

  10. Relationships between mechanical behavior in neutral environment and stress corrosion behavior for austenitic stainless steels

    International Nuclear Information System (INIS)

    Stress corrosion of two austenitic steels: Z2CN18-10 and Z6CN18-09 is studied by means of the conventional test: MgCl2-44%-1530C. Results obtained by three methods: mechanical tests, electrochemical methods, metallographic examination are compared. Mechanical studies reveal three stress regions: elastic range, uniform plastic deformation range, strong strain hardening. Stress corrosion test results are in good agreement with those obtained by mechanical tests. However, the crack propagation mechanisms seems to depend on the anodic dissolution rather than on stress range

  11. Adsorption behavior of caffeine as a green corrosion inhibitor for copper

    International Nuclear Information System (INIS)

    Electrochemical and impedance experiments were carried out to evaluate the corrosion behavior of copper in aerated 0.1 mol L−1 H2SO4 solutions in the presence of three xanthine derivatives with similar chemical structures. The corrosion rate of copper was found to increase in the presence of theophylline and theobromine and decrease in the presence of caffeine. The adsorption and inhibitory effect of caffeine on copper surfaces in aerated 0.1 mol L−1 H2SO4 solutions were then investigated in detail by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), contact angle measurements, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and fluorescence experiments. The data obtained indicate that caffeine behaves as a cathodic-type inhibitor adsorbing onto the copper surface according to the Temkin isotherm, with the negative ∆G°ads value of − 31.1 kJ mol−1 signifying a spontaneous adsorption process. The corrosion inhibition efficiency increased with caffeine concentration in the range of 1.0–10.0 mmol L−1. Furthermore, the EIS results obtained at the open-circuit potential and surface analysis (SEM, EDS and fluorescence) clearly demonstrated the adsorption of the organic compound onto the copper electrode. The contact angle measurements revealed the formation of a hydrophobic protective film. This film covers up to 72% of the total active surface, acts as a protective barrier and prevents interaction between the metal, water and oxygen molecules. - Highlights: ► We have investigated the adsorption and corrosion inhibition of caffeine on copper surfaces. ► Caffeine behaves as a cathodic-type inhibitor. ► Caffeine adsorbs onto copper surface according to Temkin isotherm. ► There exists the formation of a hydrophobic film that acts as a protective barrier. ► This corrosion inhibitor covers up to 72% of the total active surface of copper.

  12. Wear and corrosion behavior of W/WC bilayers deposited by magnetron sputtering

    International Nuclear Information System (INIS)

    WC/W coatings were deposited by reactive magnetron sputtering using 40%, 60% and 80% methane CH4 in the gas mixture. The bilayers were grown on to AISI 420 stainless-steel substrates in order to study the wear and corrosion behavior. Before growing the bilayers, one Ti monolayer was grown to improve the adherence of the coatings to the substrate. The wear resistance and the friction coefficient of the coatings were determined using a pin-on-disk tribometer. All coatings had a friction coefficient of about 0.5. The measured weight lost of the bilayers from each probe allowed the qualitative analysis of wear behavior all coatings. The bilayers grown with 80% methane showed the best abrasive wear resistance and adhesion without failure through the coating in the wear track for dry pin-on-disk sliding. Electrochemical corrosion test showed that the bilayers grown with 80% methane were more resistant to corrosion than the ones uncoated. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Corrosion behavior of mesoporous bioglass-ceramic coated magnesium alloy under applied forces.

    Science.gov (United States)

    Zhang, Feiyang; Cai, Shu; Xu, Guohua; Shen, Sibo; Li, Yan; Zhang, Min; Wu, Xiaodong

    2016-03-01

    In order to research the corrosion behavior of bioglass-ceramic coated magnesium alloys under applied forces, mesoporous 45S5 bioactive glass-ceramic (45S5 MBGC) coatings were successfully prepared on AZ31 substrates using a sol-gel dip-coating technique followed by a heat treatment at the temperature of 400°C. In this work, corrosion behavior of the coated samples under applied forces was characterized by electrochemical tests and immersion tests in simulated body fluid. Results showed that the glass-ceramic coatings lost the protective effects to the magnesium substrate in a short time when the applied compressive stress was greater than 25MPa, and no crystallized apatite was formed on the surface due to the high Mg(2+) releasing and the peeling off of the coatings. Whereas, under low applied forces, apatite deposition and crystallization on the coating surface repaired cracks to some extent, thus improving the corrosion resistance of the coated magnesium during the long-term immersion period. PMID:26703229

  14. Corrosion behavior of surface treated steel in liquid sodium negative electrode of liquid metal battery

    Science.gov (United States)

    Lee, Jeonghyeon; Shin, Sang Hun; Lee, Jung Ki; Choi, Sungyeol; Kim, Ji Hyun

    2016-03-01

    While liquid metal batteries are attractive options for grid-scale energy storage applications as they have flexible siting capacities and small footprints, the compatibility between structural materials such as current collectors and negative electrode such as sodium is one of major issues for liquid metal batteries. Non-metallic elements such as carbon, oxygen, and nitrogen in the liquid sodium influence the material behaviors of the cell construction materials in the battery system. In this study, the compatibility of structural materials with sodium is investigated in high temperature liquid sodium, and electrochemical impedance spectroscopy (EIS) is used to monitor in-situ the corrosion behavior at the surface of materials in sodium. Chemical vapor deposition (CVD) coatings of SiC and Si3N4 are applied as protective barriers against dissolution and corrosion on the steel surface. The results show that CVD coating of Si compounds can delay corrosion of steel in high temperature liquid sodium comparing to the result of as-received specimens, while SiC coating is more durable than Si3N4 coating in high temperature liquid sodium.

  15. Erosion and Corrosion Behavior of Laser Cladded Stainless Steels with Tungsten Carbide

    Science.gov (United States)

    Singh, Raghuvir; Kumar, Mukesh; Kumar, Deepak; Mishra, Suman K.

    2012-11-01

    Laser cladding of tungsten carbide (WC) on stainless steels 13Cr-4Ni and AISI 304 substrates has been performed using high power diode laser. The cladded stainless steels were characterized for microstructural changes, hardness, solid particle erosion resistance and corrosion behavior. Resistance of the clad to solid particle erosion was evaluated using alumina particles according to ASTM G76 and corrosion behavior was studied by employing the anodic polarization and open circuit potential measurement in 3.5% NaCl solution and tap water. The hardness of laser cladded AISI 304 and 13Cr-4Ni stainless steel was increased up to 815 and 725Hv100 g, respectively. The erosion resistance of the modified surface was improved significantly such that the erosion rate of cladded AISI 304 (at 114 W/mm2) was observed ~0.74 mg/cm2/h as compared to ~1.16 and 0.97 mg/cm2/h for untreated AISI 304 and 13Cr-4Ni, respectively. Laser cladding of both the stainless steels, however, reduced the corrosion resistance in both NaCl and tap water.

  16. Microstructure and Corrosion Behavior of Ni-Alloy/ CrN Nano layered Coatings

    International Nuclear Information System (INIS)

    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 1μ m. 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 Ecorr and Icorr values ranged from 10.64 to 10.33 V and 1.42 x10-5 to 1.14 x10-6 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.

  17. Influence aqueous solutions on the mechanical behavior of argillaceous rocks

    International Nuclear Information System (INIS)

    The hydration of the shale with an aqueous solution induces a swelling deformation which plays an important role in the behaviour of the structures excavated in this type of grounds. This deformation is marked by a three-dimensional and anisotropic character and involves several mechanisms like adsorption, osmosis or capillarity. Several researches were dedicated to swelling and were often much debated due to the complexity of the implied phenomena. The goal of this thesis is therefore to contribute to a better understanding of shale swelling when the rock is confined and hydrated with an aqueous solution. The main part of the work accomplished was related to the Lorraine shale and to the Tournemire shale. To characterize swelling and to identify the main governing parameters, it was necessary to start the issue with an experimental approach. Many apparatus were then developed to carry out tests under various conditions of swelling. In order to facilitate the interpretation of the tests and thereafter the modelling of the behaviour, the experimental procedure adopted consisted of studying first the mechanical aspect and then the chemical aspect of swelling. In the mechanical part, swelling was studied by imposing on the sample a mechanical loading while maintaining during the tests the same aqueous solution. The principal parameters which were studied are the effect of the lateral conditions on axial swelling (impeded strain or constant stress) as well as the influence of the axial stress on radial swelling. The anisotropy of swelling was studied by carrying out, for different orientations of the sample, tests of free swelling, impeded swelling and uniaxial swelling. These various mechanical tests allowed to study the three-dimensional anisotropic swelling in all the conditions and to select the most appropriate test to be used in the second phase of the research. The precise analysis performed to explain the mechanisms behind the swelling of an argillaceous rock

  18. Corrosion behavior of Ti-13Nb-13Zr alloy used as a biomaterial

    International Nuclear Information System (INIS)

    Titanium alloys were developed as an alternative to stainless steels and have been extensively used as biomaterials ever since. One of these alloys is Ti-13Nb-13Zr (TNZ), a near-beta phase alloy containing elements with excellent biocompatibility. The main advantage of the TNZ alloy, compared to other titanium alloys, such as Ti-6Al-4V and Ti-6Al-7Nb, widely used as biomaterials, is its low elasticity modulus, closer to that of bone, and the absence of aluminum and vanadium, which have been reported to cause long-term adverse effects. In this paper, the corrosion and electrochemical behavior of TNZ alloy (as cast and after oxygen charge) was studied in a PBS solution. The results showed that, with the oxygen load, there is a significant reduction of the anodic current in almost the whole potential spam explored in this work, meaning that the corrosion rate decreases when the doping is performed.

  19. High temperature corrosion behavior of arc-sprayed aluminum coatings on steel

    Institute of Scientific and Technical Information of China (English)

    SUN Jian-bo; WANG Yong; DONG Li-xian

    2004-01-01

    Aluminum coatings were sprayed on the substrate of steel Q235 by arc spraying. The test samples of Q235, Al coatings and Al coatings with seal coat were placed in box type electric resistance furnace at 400, 500,600, 650 ℃ when their oxidation behaviors were studied. And their oxidation kinetics curves were protracted. Microstructure, microhardness, bond strength and distribution of section elements were investigated by optical microscope(OM), Vickers microhardness instrument, electric tensile test machine and EPMA. Al coatings and Al coatings with seal coat can enhance the oxidation-resistance of substrate under 500 ℃. The latter has the best corrosion resistance. The coatings can't protect the substrate against oxidation above 600 ℃. After a long time corrosion there is enriched oxygen element at interface.

  20. Study on corrosion behavior of candidate materials in 650℃ supercritical water

    International Nuclear Information System (INIS)

    The general corrosion behavior of three candidate materials (347, HR3C and In-718) was investigated in 650 ℃/25 MPa deionized water. Morphology and composition of the surface oxide film with different exposure time were observed through FEG-SEM and EDS. The phase constitute was analyzed by GIXRD. For all the test materials, the weight loss follows typical parabolic law and the weight loss of 347 shows more than 40 times higher than that of HR3C and In-718. The oxide film of three alloys mainly consists of Ni(Cr, Fe)2O4. In-718 shows severe pitting and the oxide film of 347 appears significant spalling, while HR3C has compact oxide film. In the high temperature supercritical water, the high Cr content may enhance the general corrosion property of the alloys, while addition of Nb may be detrimental to the pitting resistance of alloys. (authors)

  1. Studies on the corrosion and wear behavior of the laser nitrided biomedical titanium and its alloys

    International Nuclear Information System (INIS)

    The effects of laser nitriding on surface hardness, corrosion and wear behavior of the conventional biomedical implants such as commercially available pure titanium and Ti-13Nb-13Zr alloy is reported. The influence of alloying elements such as Zr and Nb on nitride formation was also studied by nitriding the newly developed alloy (Ti-13Nb-13Zr). The surface modified samples were characterized using optical microscope (OM), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) techniques. Corrosion rate, wear rate and coefficient of friction were made under simulated body condition for commercially available pure titanium and Ti-13Nb-13Zr alloy. The high speed processing of these alloys enabled smooth and crack free surface.

  2. Reference electrodes behavior in the monitoring of corrosion potential at high temperature

    International Nuclear Information System (INIS)

    A fundamental difficulty, on electrochemical potential (ECP) measurements, arises in the development of high temperature reference electrode. The requirements, to get reliable data with a reference electrode, are chemical stability, potential independent of the environment, and calculability electrode potential on a thermodynamic scale (SHE). In this study, three types of high temperature reference electrodes have been developed for the use in a BWR type reactor work operating conditions. The reference electrodes were cooper/cooper (I) oxide with Yttria-Stabilized Zirconia (YSZ) membrane; a silver/silver chloride couple and Platinum. The application to corrosion potential monitoring is illustrated with several examples of measurements at different types environments. Such measurements were needed for studying the thermodynamics behavior and stability of these sensors and for determining the correlations between corrosion potential and water chemistry. (authors). 2 figs., 6 refs

  3. Structure and phase behavior of aqueous methylcellulose solutions

    Science.gov (United States)

    McAllister, John; Schmidt, Peter; Lodge, Timothy; Bates, Frank

    2015-03-01

    Cellulose ethers (CE) constitute a multi-billion dollar industry, and have found end uses in a broad array of applications from construction materials, food products, personal care products, and pharmaceuticals for more than 80 years. Methylcellulose (MC, with the trade name METHOCEL™) is a CE in which there is a partial substitution of -OH groups with -OCH3 groups. This results in a polymer that is water-soluble at low temperatures, and aqueous solutions of MC display gelation and phase separation at higher temperatures. The nature of MC gelation has been debated for many years, and this project has made significant advances in the understanding of the solution properties of CEs. We have characterized a fibrillar structure of MC gels by cryogenic transmission electron microscopy (cryo-TEM) and small angle neutron scattering (SANS). Using light scattering, turbidity measurements, and dynamic mechanical spectroscopy (DMS) we report that MC microphase separates by nucleation and growth of fibril aggregates, and is a different process from LCST phase separation.

  4. Wetting Behavior and Heat Transfer of Aqueous Graphene Nanofluids

    Science.gov (United States)

    Nayak, Vignesh U.; Prabhu, Narayan K.

    2016-04-01

    Aqueous graphene nanofluids having concentrations 0.01, 0.1, and 0.3 vol.% were used as heat transfer media during quenching of ISO 9950 inconel alloy probe. Contact angle measurements were carried out to assess the wettability of graphene nanofluids. Nanofluids showed better wettability compared to base water with over 16% reduction in their contact angles. The cooling performance of the quench media was assessed by cooling curve analysis during quenching of an instrumented inconel probe from 860 °C into the quench medium. Recorded temperature readings showed longer vapor phase stage during quenching with nanofluids. The severity of nanofluids was found to be lower relative to water. During quenching with nanofluids, the estimated spatiotemporal heat flux transients at the metal/quenchant interface showed that more heat was removed during the vapor phase stage of cooling. The present study brings out the possibility of using stable water-graphene nanoplatelet suspensions for quench heat treatment of steel components requiring cooling severity between water and oil/polymer quenchants.

  5. Effect of heat treatment on the Mechanical Properties and Corrosion Behavior of Duplex Stainless Steel Pipeline Weldments

    International Nuclear Information System (INIS)

    Duplex stainless steel (DSS) is a relatively new class of alloys characterized by a low - carbon content (< 0.03 wt %). body centered cubic ferrite . face centered cubic austenite microstructure, and additions of molybdenum, nitrogen, tungsten nd copper. the typical chromium and nickel contents are 20 to 30% and 5 to 10% respectively. the specific advantages offered by DSS over conventional 300 series stainless steel are strength (about twice that of austenitic stainless steels), chloride-stress corrosion cracking resistance and pitting corrosion resistance. these materials are used in the intermediate temperature range about-60 to 300 C where resistance to acids and aqueous chloride is required

  6. Microstructural Characterization and Corrosion Behavior of Al 7075 Alloys Using X-ray Synchrotron Tomography

    Science.gov (United States)

    Singh, Sudhanshu Shekhar

    Al 7075 alloys are used in a variety of structural applications, such as aircraft wings, automotive components, fuselage, spacecraft, missiles, etc. The mechanical and corrosion behavior of these alloys are dependent on their microstructure and the environment. Therefore, a comprehensive study on microstructural characterization and stress-environment interaction is necessary. Traditionally, 2D techniques have been used to characterize microstructure, which are inaccurate and inadequate since the research has shown that the results obtained in the bulk are different from those obtained on the surface. There now exist several techniques in 3D, which can be used to characterize the microstructure. Al 7075 alloys contain second phase particles which can be classified as Fe-bearing inclusions, Si-bearing inclusions and precipitates. The variation in mechanical and corrosion properties of aluminum alloys has been attributed to the size, shape, distribution, corrosion properties and mechanical behavior of these precipitates and constituent particles. Therefore, in order to understand the performance of Al 7075 alloys, it is critical to investigate the size and distribution of inclusions and precipitates in the alloys along with their mechanical properties, such as Young's modulus, hardness and stress-strain behavior. X-ray tomography and FIB tomography were used to visualize and quantify the microstructure of constituent particles (inclusions) and precipitates, respectively. Microscale mechanical characterization techniques, such as nanoindentation and micropillar compression, were used to obtain mechanical properties of inclusions. Over the years, studies have used surface measurements to understand corrosion behavior of materials. More recently, in situ mechanical testing has become more attractive and advantageous, as it enables visualization and quantification of microstructural changes as a function of time (4D). In this study, in situ X-ray synchrotron tomography

  7. Study on the transport behavior of uranyl nitrate in aqueous and non-aqueous systems

    International Nuclear Information System (INIS)

    The analytical ultracentrifuge has proven itself through diffusion measurements to be well suited for studying radioactive compounds. In the framework of this paper the extent to which the UV and schlieren optics of an analytical ultracentrifuge can be used for extraction-kinetic tests was tested. With this method there is also the possibility of determining the distribution coefficients right at the phase boundary. The results show the good possibility of application of the absorption and schlieren optics to the study of the transport behavior of uranyl nitrate in practice oriented solutions. (orig.)

  8. Corrosion behavior of Hastelloy-N alloys in molten salt fluoride in Ar gas or in air

    International Nuclear Information System (INIS)

    The effects of air on the corrosion of Hastelloy-N alloys in molten salt coolant containing fission product elements were investigated to determine the safety of structural materials in high-temperature reactors cooled with fluoride salt. Corrosion tests of Hastelloy-N in the molten fluoride salt FLiNaK in an alumina crucible and a graphite crucible under argon gas or air were performed at 773–923 K for 100 h. The depth of corrosive attack, as well as the extent of chromium and molybdenum depletion, increased with increasing temperature. The extent of Hastelloy-N corrosion in molten salt under air was significantly greater than under argon gas. The effect of adding the impurity cesium iodide to molten salt containing nuclear waste fuel on the corrosion behavior was negligible. (author)

  9. The corrosion inhibition and adsorption behavior of Uncaria gambir extract on mild steel in 1 M HCl

    International Nuclear Information System (INIS)

    The inhibitive effect of the ethyl acetate extract of Uncaria gambir on the corrosion of mild steel in 1 M HCl solution has been investigated by weight loss measurement as well as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The presence of this catechin-containing extract reduces remarkably the corrosion rate of mild steel in acidic solution. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 303-333 K. The results from this corrosion test clearly reveal that the extract behaves as a mixed type corrosion inhibitor with the highest inhibition at 1000 ppm. Surface analyses via scanning electron microscope (SEM) shows a significant improvement on the surface morphology of the mild steel plate. Linearity of Langmuir isotherm adsorptions indicated the monolayer formation of inhibitor on mild steel surface.

  10. Corrosion behavior of tantalum-coated cobalt-chromium modular necks compared to titanium modular necks in a simulator test.

    Science.gov (United States)

    Dorn, Ulrich; Neumann, Daniel; Frank, Mario

    2014-04-01

    This study compared the corrosion behavior of tantalum-coated cobalt-chromium modular necks with that of titanium alloy modular necks at their junction to titanium-alloy femoral stem. Tests were performed in a dry assembly and two wet assemblies, one contaminated with calf serum and the other contaminated with calf serum and bone particles. Whereas the titanium modular neck tested in the dry assembly showed no signs of corrosion, the titanium modular necks tested in both wet assemblies showed marked depositions and corrosive attacks. By contrast, the tantalum-coated cobalt-chromium modular necks showed no traces of corrosion or chemical attack in any of the three assemblies. This study confirms the protective effect of tantalum coating the taper region of cobalt-chromium modular neck components, suggesting that the use of tantalum may reduce the risk of implant failure due to corrosion. PMID:24099841

  11. A Comparison of Corrosion Behavior of Copper and Its Alloy in Pongamia pinnata Oil at Different Conditions

    Directory of Open Access Journals (Sweden)

    Meenakshi H. N. Parameswaran

    2013-01-01

    Full Text Available Vegetable oils are promising substitutes for petrodiesel as they can be produced from numerous oil seed crops that can be cultivated anywhere and have high energy contents, exhibiting clean combustion behavior with zero CO2 emission and negligible SO2 generation. The impact of biofuel on the corrosion of various industrial metals is a challenge for using biofuel as automotive fuel. Fuel comes in contact with a wide variety of metallic materials under different temperatures, velocities, and loads thereby causing corrosion during storage and flow of fuel. Hence, the present investigation compares the corrosion rates of copper and brass in Pongamia pinnata oil (O100, 3% NaCl, and oil blend with NaCl (O99 obtained by static immersion test and using rotating cage. The corrosivity and conductivity of the test media are positively correlated. This study suggested that the corrosivity of copper is higher than brass in Pongamia pinnata oil (PO.

  12. Corrosion behavior of sputter-deposited W-Nb alloys in NaCl and NaOH solutions

    Energy Technology Data Exchange (ETDEWEB)

    Jha, Himendra [Graduate School of Engineering, Hokkaido University, N13 W8, Kita-Ku, Sapporo 060-8628 (Japan); Central Department of Chemistry, Tribhuvan University, GPO Box-2040 Kathmandu (Nepal)], E-mail: himendra@elechem1-mc.eng.hokudai.ac.jp; Bhattarai, Jagadeesh [Central Department of Chemistry, Tribhuvan University, GPO Box-2040 Kathmandu (Nepal)

    2008-05-29

    The corrosion behavior of the sputter-deposited amorphous or nanocrystalline W-Nb alloys is studied in 10% NaCl, 0.1 and 1 M NaOH solutions at 24 deg. C, open to air using immersion tests and electrochemical measurements. Niobium metal acts synergistically with tungsten in enhancing the corrosion resistance of the W-Nb alloys so as to show lower corrosion rates than the corrosion rates of the alloy-constituting elements in almost all examined solutions. Corrosion rates of W-Nb alloys are about more than one order of magnitude less than that of the sputter-deposited tungsten and even lower than that of sputter-deposited niobium. The stability of the anodic passive films formed on the W-Nb alloys increase with niobium content.

  13. Corrosion behavior of sputter-deposited W-Nb alloys in NaCl and NaOH solutions

    International Nuclear Information System (INIS)

    The corrosion behavior of the sputter-deposited amorphous or nanocrystalline W-Nb alloys is studied in 10% NaCl, 0.1 and 1 M NaOH solutions at 24 deg. C, open to air using immersion tests and electrochemical measurements. Niobium metal acts synergistically with tungsten in enhancing the corrosion resistance of the W-Nb alloys so as to show lower corrosion rates than the corrosion rates of the alloy-constituting elements in almost all examined solutions. Corrosion rates of W-Nb alloys are about more than one order of magnitude less than that of the sputter-deposited tungsten and even lower than that of sputter-deposited niobium. The stability of the anodic passive films formed on the W-Nb alloys increase with niobium content

  14. Corrosion behavior of laser-clad Mo2NiB2 cermet coating on low carbon steel substrate

    International Nuclear Information System (INIS)

    A Mo2NiB2 cermet coating on low carbon steel substrate was fabricated by laser cladding technique. The coating consisted of γ-(Fe, Ni) as a metallic matrix binder and Mo2NiB2 particles as a reinforced phase distributed uniformly in the microstructure. Corrosion behavior of the coating was investigated and the commercial 1Cr, 304SS, and G3 were used for comparison. G3 exhibited the highest corrosion resistance and 1Cr the lowest corrosion resistance, whereas 304SS and the coating exhibited the intermediate and similar corrosion resistance. However, the severe pitting corrosion which was observed in 304SS did not exist for the coating. (author)

  15. The corrosion inhibition and adsorption behavior of Uncaria gambir extract on mild steel in 1 M HCl

    Energy Technology Data Exchange (ETDEWEB)

    Hussin, M. Hazwan [Material and Corrosion Chemistry Laboratory, School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang (Malaysia); Kassim, M. Jain, E-mail: mjain@usm.my [Material and Corrosion Chemistry Laboratory, School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2011-02-15

    The inhibitive effect of the ethyl acetate extract of Uncaria gambir on the corrosion of mild steel in 1 M HCl solution has been investigated by weight loss measurement as well as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The presence of this catechin-containing extract reduces remarkably the corrosion rate of mild steel in acidic solution. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 303-333 K. The results from this corrosion test clearly reveal that the extract behaves as a mixed type corrosion inhibitor with the highest inhibition at 1000 ppm. Surface analyses via scanning electron microscope (SEM) shows a significant improvement on the surface morphology of the mild steel plate. Linearity of Langmuir isotherm adsorptions indicated the monolayer formation of inhibitor on mild steel surface.

  16. Corrosion behavior of Zn and Zn-Al alloy coated steels under cyclic wet-dry environments

    International Nuclear Information System (INIS)

    Atmospheric corrosion behaviors of Zn, Zn-5%Al and Zn-55%Al coated steels have been investigated under cyclic wet-dry environments containing chloride ions. The wet-dry cycle was carried out by alternate exposure to immersion in 0.5 M (or 0.05 M) NaCl solutions and drying at 25 .deg. C and 60 %RH. The polarization resistance Rp and solution resistance Rs were monitored by AC impedance technique. From the obtained 1/Rp and 1/Rs and values, the corrosion rate of the coatings and the Time of Wetness (TOW) were estimated, respectively. Effects of chloride ions and TOW on the corrosion rates of Zn, Zn-5%Al and Zn-55%Al coatings and appearance of red rust (onset of underlying steel corrosion) under wet-dry cycles are discussed on the basis of the corrosion monitoring data

  17. Detecting the Biopolymer Behavior of Graphene Nanoribbons in Aqueous Solution.

    Science.gov (United States)

    Wijeratne, Sithara S; Penev, Evgeni S; Lu, Wei; Li, Jingqiang; Duque, Amanda L; Yakobson, Boris I; Tour, James M; Kiang, Ching-Hwa

    2016-01-01

    Graphene nanoribbons (GNR), can be prepared in bulk quantities for large-area applications by reducing the product from the lengthwise oxidative unzipping of multiwalled carbon nanotubes (MWNT). Recently, the biomaterials application of GNR has been explored, for example, in the pore to be used for DNA sequencing. Therefore, understanding the polymer behavior of GNR in solution is essential in predicting GNR interaction with biomaterials. Here, we report experimental studies of the solution-based mechanical properties of GNR and their parent products, graphene oxide nanoribbons (GONR). We used atomic force microscopy (AFM) to study their mechanical properties in solution and showed that GNR and GONR have similar force-extension behavior as in biopolymers such as proteins and DNA. The rigidity increases with reducing chemical functionalities. The similarities in rigidity and tunability between nanoribbons and biomolecules might enable the design and fabrication of GNR-biomimetic interfaces. PMID:27503635

  18. The Unusual Conformational Behavior of Polyzwitterionic Brushes in Aqueous Solutions

    Science.gov (United States)

    Mao, Jun; Chen, Wei; Yuan, Guangcui; Yu, Jing; Tirrell, Matthew

    Polyzwitterions constitute a peculiar class of polyelectrolytes, which are electrically neutral polymers containing both a positive and a negative charge on each repeating unit. Surfaces coated with polyzwitterionic brushes are resistant to the nonspecific accumulation of proteins and microorganisms, making them excellent candidates for a wide range of antifouling applications, from biocompatible medical devices to marine coatings. The surrounding environment can dramatically influence the conformational behavior of polyzwitterionic brushes. High-density polyzwitterionic brushes poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) were synthesized using surface initiated atom-transfer radical polymerization, and neutron reflectivity (NR) measurements were performed to investigate the ionic strength dependence of the conformational behaviors of PMPC brushes in monovalent salt solutions. Despite the numerous observations of normal pure polyelectrolyte brushes, NR results showed that both the densely concentrated layer near the substrate surface and the relatively swollen layer into the solution have been observed in different q range in a single neutron reflectivity profile. These results will definitely help us to better understand the relationship between the solution behaviors of zwitterionic polymer brushes and their antifouling properties.

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

    Energy Technology Data Exchange (ETDEWEB)

    Leiva-Garcia, R.; Munoz-Portero, M.J. [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, E-46071 Valencia (Spain); Garcia-Anton, J. [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, E-46071 Valencia (Spain)], E-mail: jgarciaa@iqn.upv.es

    2010-03-15

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  1. Influence of the interface composition on the corrosion behavior of unbalanced magnetron grown niobium coatings on steel

    International Nuclear Information System (INIS)

    Niobium is well known as a chemically extremely stable material. However, the corrosion performance of 0.3 to 1.3 μm thick, unbalanced magnetron (UBM) grown niobium coatings on stainless steel substrates depends not only on the deposition parameters, but also significantly on the in vacuo etching pretreatment of the substrates prior to coating. Corrosion tests, transmission electron microscopy, and scanning transmission electron microscopy analyses have shown, that a dense fine grained, partially implanted, 5-10 nm thick niobium interface layer formed during the metal ion etching pretreatment is paramount to protect stainless steel substrates thoroughly against corrosion in chlorine containing aqueous electrolytes, whereas the pretreatment with Ar and Cr ions leads to comparably inferior corrosion results. Moreover the energy of the impinging Nb ions used during the etching process plays an important role. For 0.3 μm thick Nb coatings, maximum pitting potentials (+1000 mV) and minimum corrosion currents (-6 A cm-2) were found for bias voltages between -600 and -1000 V. In summary, the results suggest that the UBM deposited Nb coatings are not completely dense and that the major justification for niobium as corrosion barrier depends on the existence of the thin interface layer generated by high-energy ion bombardment during the etching step. The UBM deposited coating (US=75 V) acts therefore as itself a chemically stable mechanical spacer protecting the thin interface layer against mechanical damage

  2. Effect of surface roughness on corrosion behavior of Alloy 690TT in simulated primary coolant of PWRs

    International Nuclear Information System (INIS)

    The corrosion products transported into the primary coolant may be activated in the core or re-deposited on the surface of components in primary coolant system including fuel cladding. Nickel cations released from the steam generator tubes cause the serious problems in PWRs, for instance, radiation exposure during maintenance operation, occurrence of axial offset anomaly (AOA) and reduction in plant operation. Some studies have been carried out to characterize the oxide layer grown on a Ni-base alloy in primary water chemical condition, especially on morphology and chemical composition. The oxide layer was deemed to a duplex structure composed to an inner Cr rich layer and an outer spinel layer rich in iron or nickel. The composition and morphology of oxide layer are affected by surface finish, operating condition, and water chemistry. Above all, surface roughness, which is one of the commercial requirements for steam generator tube of PWRs, is extremely important in terms of corrosion degradation and corrosion products. In this study, we report the effect of surface roughness on corrosion behavior in simulated primary water at 330 .deg. C and at 150 bar. The surface roughness was controlled to evaluate its difference in corrosion property using mechanical grinding and polishing method. It was measured using a surface profiler and morphology of oxide layer was investigated with FESEM. The corrosion rate of Alloy 690TT samples was calculated by descale-gravimetric analysis. We investigate the effect of surface roughness on corrosion behavior of Alloy 690TT in the simulated primary coolant environments of a pressurized water reactor. Surface roughness of samples were controlled from 716 nm to 25 nm to evaluate for the effect of surface roughness on corrosion behavior Polyhedral oxide particles were formed on the grounded surfaces, whereas the mixed oxides of polyhedral and needle-like structure formed on the polished surface. The corrosion rate of samples was

  3. Phase Behavior of Light Gases in Hydrocarbon and Aqueous Solvents.

    Energy Technology Data Exchange (ETDEWEB)

    Gasem, K.A.M.; Robinson, R.L., Jr.; Gao, W.; Ratzalff, D.W.

    1997-10-01

    Under previous support from the Department of Energy, an experimental facility has been established and operated to measure valuable vapor-liquid equilibrium data for systems of interest in the production and processing of coal fluids. To facilitate the development and testing of models for prediction of the phase behavior for such systems, we have acquired substantial amounts of data on the equilibrium phase compositions for binary mixtures of heavy hydrocarbon solvents with a variety of supercritical solutes, including hydrogen, methane, ethane, carbon monoxide, and carbon dioxide. The present project focuses on measuring the phase behavior of light gases and water in Fischer-Tropsch (F-T) type solvents at conditions encountered in indirect liquefaction processes and evaluating and developing theoretically-based correlating frameworks to predict the phase behavior of such systems. Specific goals of the proposed work include (a) developing a state-of-the-art experimental facility to permit highly accurate measurements of equilibrium phase compositions (solubilities) of challenging F-T systems, (b) measuring these properties for systematically-selected binary, ternary and molten F-T wax mixtures to provide critically needed input data for correlation development, (c) developing and testing models suitable for describing the phase behavior of such mixtures, and (d) presenting the modeling results in generalized, practical formats suitable for use in process engineering calculations. During the present reporting period, the solubility of carbon monoxide, hydrogen, and nitrogen in n-dodecane were measured using a static equilibrium cell over the temperature range from 344.3 to 410.9 K and pressures to 13.2 MPa. The uncertainty in these new solubility measurements is estimated to be less than 0.001 in mole fraction. The data were analyzed using the Peng-Robinson (PR) equation of state (EOS). In general, the PR EOS represents the experimental data well when two

  4. Effects of cold work, sensitization treatment and its combination on corrosion behavior of stainless steels in nitric acid

    International Nuclear Information System (INIS)

    In the Purex reprocessing process, the spent nuclear fuels from light water reactors are dissolved in nitric acid to separate and recover the fissile materials such as Uranium and Plutonium from the radioactive fission products. To ensure safety and reliable operation of the reprocessing plant, superior corrosion resistance is required to the structural materials of the plant, and stainless steels have been used as one of the main structural materials because of its very good performance in a nitric acid environment. Corrosion behavior of stainless steels was investigated in nitric acid for the effect of cold work, sensitization heat treatment and its combination. Corrosion rate of solution-treated Type 304 with extra low carbon (304 ELC) increased with time and reached constant values after 1,000 h of immersion time. Constant corrosion rates, however, were obtained for 25Cr-20Ni-Nb (310 Nb) from the initial stage of immersion. Cold work mitigated corrosion of the solution-treated stainless steels. The effect of cold work was different on the two stainless steels with sensitization heat treatment, showing accelerated corrosion for 304 ELC. The corrosion resistance of 310 Nb was superior to 304ELC after all the treatments. Chromium concentration of the sensitization treated 304 ELC was lower in the grain-boundary region than that of the solution-treated one, although no chromium carbide precipitation was observed. This might be the cause of corrosion enhancement by sensitization treatment

  5. A comparative corrosion behavior of Mg, AZ31 and AZ91 alloys in 3.5% NaCl solution

    Directory of Open Access Journals (Sweden)

    I.B. Singh

    2015-06-01

    Full Text Available The corrosion behavior of Mg, AZ31 and AZ91 has been evaluated in 3.5% NaCl solution using weight loss, electrochemical polarization and impedance measurements. Corrosion rate derived from the weight losses demonstrated the occurrence of steeply fast corrosion reaction on AZ91 alloy after three hours of immersion, indicating the start of galvanic corrosion. An increase of corrosion rate with immersion time was also observed for AZ31 but with lesser extent than AZ91 alloy. Whereas Mg metals showed a decrease of corrosion rate with immersion time, suggesting the formation of a protective layer on their surfaces. In contrast, the corrosion current density (Icorr derived from the Tafel plots, exhibited their corrosion resistances in order of Mg > AZ91 > AZ31. Electrochemical charge transfer resistance (Rct and double layer capacitance measured by electrochemical impedance spectroscopy (EIS, are well in accordance with the measured Icorr. EIS measurements with time and microstructural examination of the corroded and uncorroded samples are helpful in elucidation of results measured by electrochemical polarization.

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

    International Nuclear Information System (INIS)

    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

  7. Influence of Dispersoids on Corrosion Behavior of Oxide Dispersion-Strengthened 18Cr Steels made by High-Energy Milling

    Science.gov (United States)

    Nagini, M.; Jyothirmayi, A.; Vijay, R.; Rao, Tata N.; Reddy, A. V.; Rajulapati, Koteswararao V.; Sundararajan, G.

    2016-02-01

    Corrosion behavior of 18Cr ferritic steel with and without yttria produced by high-energy milling followed by hot extrusion was studied in 3.5% NaCl solution using electrochemical and immersion techniques. The cyclic polarization study showed that pitting corrosion is predominant in all the materials. The pitting rate is higher in yttria dispersed steels and also increases with milling time. Impedance analysis revealed the formation of better corrosion resistance film on the surface of the steel without yttria. Potentiodynamic polarization studies indicated that the corrosion rate decreased up to 48 h of exposure time and increased beyond 48 h. The increase in corrosion rate beyond 48 h is due to the porous passive film. The corrosion behavior of all the materials in immersion studies followed the same trend as observed in electrochemical studies. Even though the corrosion rate of yttria dispersed 18Cr ferritic steel is less than that of the base material, the difference is marginal. The presence of dispersoids appears to promote nucleation of pits when compared to the steel without the dispersoids.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mhaede, Mansour, E-mail: mansour.mhaede@yahoo.com [Institute of Materials Science and Engineering, Clausthal University of Engineering, Agicolastr.6, 38678 Clausthal-Zellerfeld (Germany); Faculty of Engineering, Zagazig University, 44519 Zagazig (Egypt); Ahmed, Aymen; Wollmann, Manfred; Wagner, Lothar [Institute of Materials Science and Engineering, Clausthal University of Engineering, Agicolastr.6, 38678 Clausthal-Zellerfeld (Germany)

    2015-05-01

    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.

  9. SEM examination of the oxide-metal interface formed during the aqueous corrosion of a Zr-2.5 wt%Nb alloy

    International Nuclear Information System (INIS)

    The oxide-metal interface formed during the aqueous corrosion of a Zr-2.5 wt% Nb alloy has been studied by scanning electron microscopy, using a specimen preparation method which also has potential application to other materials containing an oxide-metal interface. The oxidation of cold-worked Zr-2.5 wt% Nb pressure tubing in pressurized lithiated water proceeds first along grain boundaries at which there is β-zirconium or its decomposition products, and then continues on the α-zirconium grains. Oxides at the oxide-metal interface formed in an aqueous environment were mainly extended along grain boundaries, and were characterized by long filaments which consisted of many fine zirconia grains. This oxidation behaviour is attributed to short-circuit diffusion at the grain boundaries which is caused by the nature of the crystallite boundaries of the oxide, the flaws arising from the oxidation of the grain boundary phases (β-Zr, its decomposition products as well as impurities), and cracking of the oxide due to phase transformations in ZrO2. When different plane section of the tubing are corroded, there are different corrosion rates, with the sections containing a higher area fraction of the grain boundaries with β-zirconium exhibiting higher corrosion rates. The formation of long 'fingers' of oxide made up of longer filaments of oxide, together with the higher corrosion rates in the post-transition specimens, result in the destruction of the barrier oxide layer and an increase in the oxide rate. (author)

  10. Effect of alloying elements Zr,Cr,V on corrosion behavior of Ti-Ni-Nb shape memory alloy

    International Nuclear Information System (INIS)

    In this paper, by testing anodic polarization curves of Ti-Ni-Nb based shape memory alloys, the stability of passive film was investigated after alloying with elements Zr,Cr,V. In artificial sea water (3.5%NaCl) and physiological solution (5%NaCl+0.1%H2O2), the results show that the alloying elements influence the corrosion behavior of Ti-Ni-Nb alloy. Generally, Zr improves the corrosion resistance of Ti-Ni-Nb alloy, Cr reduces its corrosion resistance and V does not change the property. (orig.)

  11. Corrosion and environment-assisted cracking behavior of friction stir welded Al 2195 and Al 2219 alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hu Wusheng; Meletis, E.I. [Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Mechanical Engineering

    2000-07-01

    The friction stir welding (FSW) process has been evaluated for application on the Al 2195 cryogenic tank of the space transportation system. In the present study, the general corrosion, pitting and stress corrosion cracking (SCC) resistance of 2195 plates joined by FSW was investigated. Plates of Al 2219 joined by FSW were also tested for comparison purposes along with Al 2195 and Al 2219 plates joined by the variable polarity plasma arc welding method. The general corrosion, SCC and pitting behavior of FSW Al 2195 and Al 2219 is presented and discussed. (orig.)

  12. Corrosion Behavior in 3.5% NaCl Solutions of γ-TiAl Processed by Electron Beam Melting Process

    Directory of Open Access Journals (Sweden)

    Asiful Hossain Seikh

    2015-12-01

    Full Text Available In this work, the corrosion behavior of γ-TiAl alloy produced by electron beam melting (EBM process in 3.5% NaCl solution was reported. The study has been performed using potentiodynamic polarization resistance and electrochemical impedance spectroscopy techniques and complemented by scanning electron microscopy investigations. All measurements were carried out after different periods of alloy exposure in the chloride solutions and at different temperatures. The results showed that the EBM produced γ-TiAl alloy has excellent corrosion resistance confirmed by the high values of polarization resistance and the low values of corrosion current and corrosion rate. With increase in immersion time, the corrosion potential moved to a higher positive value with a decrease in corrosion current and corrosion rate, which suggests an improvement in corrosion resistance. On the other hand, the increase of temperature was found to significantly increase the corrosion of the processed γ-TiAl alloy.

  13. Corrosion behavior of Alloy 690 and Alloy 693 in simulated nuclear high level waste medium

    Energy Technology Data Exchange (ETDEWEB)

    Samantaroy, Pradeep Kumar; Suresh, Girija; Paul, Ranita [Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Kamachi Mudali, U., E-mail: kamachi@igcar.gov.in [Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Raj, Baldev [Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2011-11-15

    Highlights: > Alloy 690 and Alloy 693, both possess good corrosion resistance in simulated HLW. > SEM and EDS confirms the presence of Cr rich precipitates for both the alloys. > Passive film stability of Alloy 690 was found to be higher than Alloy 693. > Both alloys possess few micro pits even at a concentration of 100 ppm Cl{sup -} ion. - Abstract: Nickel based alloys are candidate materials for the storage of high level waste (HLW) generated from reprocessing of spent nuclear fuel. In the present investigation Alloy 690 and Alloy 693 are assessed by potentiodynamic anodic polarization technique for their corrosion behavior in 3 M HNO{sub 3}, 3 M HNO{sub 3} containing simulated HLW and in chloride medium. Both the alloys were found to possess good corrosion resistance in both the media at ambient condition. Microstructural examination was carried out by SEM for both the alloys after electrolytic etching. Compositional analysis of the passive film formed on the alloys in 3 M HNO{sub 3} and 3 M HNO{sub 3} with HLW was carried out by XPS. The surface of Alloy 690 and Alloy 693, both consists of a thin layer of oxide of Ni, Cr, and Fe under passivation in both the media. The results of investigation are presented in the paper.

  14. In vitro corrosion behavior and cytotoxicity property of magnesium matrix composite with chitosan coating

    Institute of Scientific and Technical Information of China (English)

    戴翌龙; 余琨; 陈良建; 陈畅; 乔雪岩; 颜阳

    2015-01-01

    Mg-6%Zn-10%β-Ca3(PO4)2 composite was prepared through powder metallurgy methods with different chitosan coatings on its surface. The properties of the chitosan coatings on the surface of Mg-6%Zn-10%β-Ca3(PO4)2 composite, such as the adhesion ability, the corrosion behavior and the cytotoxicity properties, were investigated, and the microstructure of the chitosan coating was observed by scanning electron microscope (SEM). The results show that chitosan coating improves the corrosion resistance of the magnesium composite specimens significantly. Mg-6%Zn-10%β-Ca3(PO4)2 composite specimens exhibit good corrosion resistance and low pH values in simulated body fluid (SBF) at 37 °C in the immersion test with 7-layer chitosan coating whose relative molecular mass is 30×104 Da. The cytotoxicity tests indicate that Mg-6%Zn-10%β-Ca3(PO4)2 with chitosan coating is nontoxic with a cytotoxicity grade of zero against L-929 cells, which is better than that of uncoated composites.

  15. Effect of Carbide Distribution on Corrosion Behavior of the Deep Cryogenically Treated 1.2080 Steel

    Science.gov (United States)

    Amini, Kamran; Akhbarizadeh, Amin; Javadpour, Sirus

    2016-02-01

    Deep cryogenic heat treatment is a supplementary process performed on steels specifically tool steels before tempering to improve the wear resistance and hardness of these materials. The carbide distribution changes via the electric current flow or the application of a magnetic field during the deep cryogenic heat treatment. Hence, the electric current and the magnetic field were applied to the samples to investigate the corrosion behavior of the deep cryogenically treated samples by electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The results showed that increasing the carbide percentage and achieving a more homogenous carbide distribution during the deep cryogenic heat treatment will remarkably decrease the corrosion resistance due to a decrease in the solutionized chromium atoms in the structure as well as the increase in the martensite-carbide grain boundaries (the galvanic cell areas). Moreover, it was clarified that the electric current flow and magnetic fields reduce the carbide percentage, which leads to an increase in the corrosion resistance of these samples in comparison with the deep cryogenically treated samples.

  16. Corrosion behavior of modified nano carbon black/epoxy coating in accelerated conditions

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • By using SDS as a surfactant, nano particles of CB were uniformly dispersed. • CB nanoparticle in the epoxy coating improved the corrosion resistance of the coating. • By addition of CB nanoparticles to the epoxy diffusion ions and water became limited. • The dominance of barrier mechanism was proved by calculation of the diffusion coefficients. - Abstract: The electrochemical behavior and anticorrosion properties of modified carbon black (CB) nanoparticles in epoxy coatings were investigated in accelerated conditions. Nanoparticles of CB were modified by sodium dodecyl sulfate (SDS) as surfactant. Dispersion of nanoparticles into epoxy was confirmed by Transmission Electron Microscopy (TEM). The accelerated condition was prepared at 65 °C. CB nanoparticles improved corrosion resistance of the epoxy coating. The optimum concentration of CB in the epoxy coating was 0.75 wt%. Results showed that the CB hinder the corrosion due to its barrier properties. CB can decrease the diffusion coefficient of water in the coating with filling the micropores

  17. Corrosion behavior of modified nano carbon black/epoxy coating in accelerated conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemi-Kahrizsangi, Ahmad; Shariatpanahi, Homeira, E-mail: shariatpanahih@ripi.ir; Neshati, Jaber; Akbarinezhad, Esmaeil

    2015-03-15

    Graphical abstract: - Highlights: • By using SDS as a surfactant, nano particles of CB were uniformly dispersed. • CB nanoparticle in the epoxy coating improved the corrosion resistance of the coating. • By addition of CB nanoparticles to the epoxy diffusion ions and water became limited. • The dominance of barrier mechanism was proved by calculation of the diffusion coefficients. - Abstract: The electrochemical behavior and anticorrosion properties of modified carbon black (CB) nanoparticles in epoxy coatings were investigated in accelerated conditions. Nanoparticles of CB were modified by sodium dodecyl sulfate (SDS) as surfactant. Dispersion of nanoparticles into epoxy was confirmed by Transmission Electron Microscopy (TEM). The accelerated condition was prepared at 65 °C. CB nanoparticles improved corrosion resistance of the epoxy coating. The optimum concentration of CB in the epoxy coating was 0.75 wt%. Results showed that the CB hinder the corrosion due to its barrier properties. CB can decrease the diffusion coefficient of water in the coating with filling the micropores.

  18. Study on Microstructure and Electrochemical Corrosion Behavior of PEO Coatings Formed on Aluminum Alloy

    Science.gov (United States)

    Xiang, N.; Song, R. G.; Li, H.; Wang, C.; Mao, Q. Z.; Xiong, Y.

    2015-12-01

    Plasma electrolytic oxidation (PEO) treated 6063 aluminum alloy was applied in a silicate- and borate-based alkaline solution. The microstructure and electrochemical corrosion behavior were studied by scanning electron microscopy, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization techniques. The results showed that the silicate-based PEO coating was of a denser structure compared with that of borate-based PEO coating. In addition, the silicate-based PEO coating was composed of more phased (Al9Si) than borate-based PEO coating. The results of corrosion test indicated that the silicate-based PEO coating provided a superior protection to 6063 aluminum alloy substrate, while borate-based PEO coating with a porous structure showed an inferior conservancy against corrosive electrolyte. Furthermore, the EIS tests proved that both coatings were capable to resist the aggressive erosion in 0.5 M NaCl solution after 72 h of immersion. However, the borate-based PEO coating could not provide sufficient protection to the substrate after 72-h immersion in 1 M NaCl solution.

  19. Influence of Ga and Hg on microstructure and electrochemical corrosion behavior of Mg alloy anode materials

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effects of Hg and Ga on the electrochemical corrosion behavior of Mg-5%Hg (molar fraction) alloys were investigated by the measurement of polarization curves and galvanostatic test. The microstructure of the alloys and the corroded surface of the specimens were investigated by scanning electron microscopy, X-ray diffractometry and emission spectrum analysis. It can be concluded that the addition of 1%Ga (molar fraction) reduces corrosion current density from 26.98 mA/cm2 to 2.34 mA/cm2;while the addition of 1%Hg (molar fraction) increases corrosion current density. The addition of Ga and Hg both promotes the electrochemical activity of the alloys and the influence of Ga is more effective than Hg. Mg-5%Hg-1%Ga alloy has the best electrochemical activity, showing mean potential of-1.992 V. The activation mechanism of the magnesium alloy produced by Hg and Ga was put forward. Magnesium atoms are dissolved in liquid Hg and Ga to form amalgam and undergo severe oxidation at the amalgam/electrolyte interface.

  20. Behavior of tritium permeation induced by water corrosion of alpha iron around room temperature

    International Nuclear Information System (INIS)

    Tritium (T) permeation leakage to surroundings is a great safety concern in fission and fusion reactor systems. T permeation potentially occurs from T contaminated water through cooling tubes or storage tank made of metals which dissolve some T evolved by water corrosion. In order to understand behaviors of hydrogen uptake and permeation in pure α-iron (αFe) during water corrosion around room temperature, hydrogen permeation experiments for an αFe membrane have been conducted by means of tritium tracer techniques. The present study suggests that hydrogen produced by water corrosion of αFe is trapped in product oxide layers to delay hydrogen uptake in αFe for a moment. However, the oxide layers do not work as a sufficient barrier for hydrogen uptake. Some of hydrogen dissolved in αFe normally diffuses and permeates through the bulk in the early stage of permeation. In a later stage, hydrogen permeation could be apparently stopped by the disappearance of concentration difference of tritium. Hydrogen partial pressure at the water/αFe interface could be ranged from 0.7 to 9.5 kPa around room temperature

  1. Influence of residual stresses and loading frequencies on corrosion fatigue crack growth behavior of weldments

    Science.gov (United States)

    Kitsunai, Y.; Tanaka, M.; Yoshihisa, E.

    1998-04-01

    The effect of residual stresses and loading frequencies on corrosion fatigue crack growth behavior under synthetic seawater with a free corrosion potential was examined using center-cracked tension (CCT) and single edge-cracked tension (SECT) specimens machined from mild steel butt-welded joints and the parent material. A series of fatigue crack growth tests were carried out with a sinusoidal loading wave form at a stress ratio of 0.05 with a loading frequency of 0.017 to 6.7 Hz. The results show that the crack growth resistance of a weld metal in the SECT specimen is higher than that in the CCT specimen regardless of testing conditions. The discrepancy is attributed to the differences in residual stress distribution at the crack tip in the two specimen geometries. The crack growth rate of the weld metal in the CCT specimen in seawater increased with decreasing loading frequency. The acceleration of the crack growth rate may be related to the occurrence of brittle striation or cleavage due to hydrogen embrittlement. It was found that the corrosion fatigue crack growth rate of a welded joint with tensile residual stress can be predicted using the effective stress intensity factor range, which takes into account both the residual stress and the loading frequency effects.

  2. Corrosion behavior of dental alloys used for retention elements in prosthodontics.

    Science.gov (United States)

    Nierlich, Judith; Papageorgiou, Spyridon N; Bourauel, Christoph; Hültenschmidt, Robert; Bayer, Stefan; Stark, Helmut; Keilig, Ludger

    2016-06-01

    The purpose of this study was to investigate the corrosion behavior of 10 different high noble gold-based dental alloys, used for prosthodontic retention elements, according to ISO 10271. Samples of 10 high-noble and noble gold-based dental alloys were subjected to: (i) static immersion tests with subsequent analysis of ion release for eight different elements using mass spectrometry; (ii) electrochemical tests, including open-circuit potential and potentiodynamic scans; and (iii) scanning electron microscopy, followed by energy-dispersive X-ray microscopy. The results were analyzed using one-way ANOVA and Sidak multiple-comparisons post-hoc test at a level of significance of α = 0.05. Significant differences were found among the 10 alloys studied for all ions (P corrosion defects, whilst the energy-dispersive X-ray analysis found no significant alteration in the elemental composition of the alloys. The results of this study reveal the variability in the corrosive resistance among the materials used for retention elements in prosthodontics. PMID:27061513

  3. Corrosion behavior of as-cast binary Mg-Bi alloys in Hank's solution

    Directory of Open Access Journals (Sweden)

    Wei-li Cheng

    2015-11-01

    Full Text Available Biodegradable Mg-xBi (x = 3, 6 and 9wt.% alloys were fabricated by ingot casting, and the change of corrosion behavior of the alloys in the Hank's solution was analyzed with respect to the microstructure using optical micrograph (OM, X-ray diffraction (XRD, scanning electron microscope (SEM equipped with an energy dispersive X-ray spectrometer (EDS, electrochemical and immersion tests. The results show that the microstructures of the as-cast Mg-Bi alloys mainly consisted of dendritic ?Mg grains and Mg3Bi2 phase in common, with the secondary dendrite arm spacing (SDAS decreasing significantly from 41.2 靘 to 25.4 靘 and the fraction of Mg3Bi2 increasing from 3.1% to 10.7%. Furthermore, the corrosion rate increasing from 1.32 mm昦-1 to 8.07 mm昦-1 as the Bi content was increased from 3wt.% to 9wt.%. The reduced corrosion resistance was mainly ascribed to the increasing fraction of the second phase particles, which bring positive effects on the development of pitting.

  4. Corrosion Behavior of Ni3(Si,Ti + 2Mo in Hydrochloric Acid Solution

    Directory of Open Access Journals (Sweden)

    Gadang Priyotomo

    2013-10-01

    Full Text Available The corrosion behavior of Ni3(Si,Ti + 2Mo intermetallic compound (L12 and (L12 + Niss mixture region has been investigated using an immersion test, polarization method and surface analytical method (scanning electron microscope and energy-dispersive X-Ray spectrometry in 0.5 kmol/m3 hydrochloric acid (HCl solution at 303 K.  In addition, the results obtained were compared to those of the L12 single-phase Ni3(Si,Ti intermetallic compound and C 276 alloy.  It was found that Ni3(Si,Ti + 2Mo had the preferential dissolution of L12 with a lower Mo concentration compared to (L12 + Niss mixture region.  From the immersion test and polarization curves, Ni3(Si,Ti + 2Mo and C276 showed the lowest corrosion resistance and the highest corrosion resistance in the solution, respectively.  From this work, It implied that unlike C276, Ni3(Si,Ti +2Mo intermetallic compound was difficult to form a stable passive film in HCl solution as well as Ni3(Si,Ti in the same solution.

  5. Determination of benzotriazole corrosion inhibitors from aqueous environmental samples by liquid chromatography-electrospray ionization-tandem mass spectrometry.

    Science.gov (United States)

    Weiss, Stefan; Reemtsma, Thorsten

    2005-11-15

    The first method for the determination of commonly used corrosion inhibitors in environmental water samples by liquid chromatography-electrospray ionization-tandem mass spectrometry is presented. Benzotriazole (BTri) and the two isomers of tolyltriazole (5- and 4-TTri) are separated in an isocratic run. By gradient elution, BTri, 4-TTri, 5-TTri, and xylyltriazole can be determined simultaneously with three benzothiazoles, but here TTri isomers coelute. The instrumental detection limit of 2 pg allows the determination of the three most important benzotriazoles from municipal wastewater and most surface waters by direct injection into the HPLC system without previous enrichment. When solid-phase extraction is employed with mean recovery rates of 95-113%, the limit of quantification for benzotriazoles range from 10 ng/L in groundwater to 25 ng/L in untreated wastewater. BTri and TTri were determined in municipal wastewater in microgram per liter concentrations. Elimination in wastewater treatment appears to be poor, and BTri and TTri can be followed through a water cycle from treated municipal wastewater through surface water to bank filtrate used for drinking water production. The TTri isomers show markedly different biodegradation behavior with 4-TTri being more stable. PMID:16285694

  6. Corrosion behavior of environmental assessment glass in product consistency tests of extended duration

    International Nuclear Information System (INIS)

    We have conducted static dissolution tests to study the corrosion behavior of the Environmental Assessment (EA) glass, which is the benchmark glass for high-level waste glasses being produced at US Department of Energy facilities. These tests were conducted to evaluate the behavior of the EA glass under the same long-term and accelerated test conditions that are being used to evaluate the corrosion of waste glasses. Tests were conducted at 90 C in a tuff groundwater solution at glass surface area/solution volume (WV) ratios of about 2000 and 20,000 m-1. The glass dissolved at three distinct dissolution rates in tests conducted at 2000 m-1. Based on the release of boron, dissolution within the first seven days occurred at a rate of about 0.65 g/(m2 · d). The rate between seven and 70 days decreased to 0.009 g/(m2 · d). An increase in the dissolution rate occurred at longer times after the precipitation of zeolite phases analcime, gmelinite, and an aluminum silicate base. The dissolution rate after phase formation was about 0.18 g/(m2 · d). The formation of the same zeolite alteration phases occurred after about 20 days in tests at 20,000 m-. The average dissolution rate over the first 20 days was 0.5 g/(m2 · d) and the rate after phase formation was about 0.20 g/(m2 · d). An intermediate stage with a lower rate was not observed in tests at 20,000 m-1. The corrosion behavior of EA glass is similar to that observed for other high-level waste glasses reacted under the same test conditions. The dissolution rate of EA glass is higher than that of other high-level waste glasses both in 7-day tests and after alteration phases form

  7. Some features of beryllium corrosion behavior in Be-liquid Li-V-4Ti-4Cr alloy system

    International Nuclear Information System (INIS)

    Recent experimental results on beryllium corrosion behavior in a V-4Ti-4Cr alloy, liquid lithium static system during testing for 200-500 h at temperatures from 600 to 800 deg. C are presented. The influence of test conditions (temperature, duration and lithium purity) and beryllium characteristics (microstructure, grain size and chemical composition) on weight loss of beryllium and penetration of lithium into beryllium are discussed. Results of compressive tests for beryllium specimens before and after corrosion testing are also introduced

  8. PHASE BEHAVIOR OF LIGHT GASES IN HYDROGEN AND AQUEOUS SOLVENTS

    Energy Technology Data Exchange (ETDEWEB)

    KHALED A.M. GASEM; ROBERT L. ROBINSON, JR.

    1999-03-31

    Under previous support from the US Department of Energy, an experimental facility has been established and operated to measure valuable vapor-liquid equilibrium data for systems of interest in the production and processing of coal fluids. To facilitate the development and testing of models for prediction of the phase behavior for such systems, we have acquired substantial amounts of data on the equilibrium phase compositions for binary mixtures of heavy hydrocarbon solvents with a variety of supercritical solutes, including hydrogen, methane, ethane, carbon monoxide, and carbon dioxide. The present project focuses on measuring the phase behavior of light gases and water in Fischer-Tropsch (F-T) type solvents at conditions encountered in indirect liquefaction processes and evaluating and developing theoretically-based correlating frameworks to predict the phase behavior of such systems. Specific goals of the proposed work include (a) developing a state-of-the-art experimental facility to permit highly accurate measurements of equilibrium phase compositions (solubilities) of challenging F-T systems, (b) measuring these properties for systematically-selected binary, ternary and molten F-T wax mixtures to provide critically needed input data for correlation development, (c) developing and testing models suitable for describing the phase behavior of such mixtures, and (d) presenting the modeling results in generalized, practical formats suitable for use in process engineering calculations. During the present reporting period, the solubilities of hydrogen in n-hexane, carbon monoxide in cyclohexane, and nitrogen in phenanthrene and pyrene were measured using a static equilibrium cell over the temperature range from 344.3 to 433.2 K and pressures to 22.8 MPa. The uncertainty in these new solubility measurements is estimated to be less than 0.001 in mole fraction. The data were analyzed using the Peng-Robinson (PR) equation of state (EOS). In general, the PR EOS represents

  9. Corrosion behaviour of an AlZnSnSrGa alloy in aqueous solutions of NaCl and Na2SO4

    OpenAIRE

    S. MENTUS; P. ZIVKOVIC; J. PJESCIC

    2000-01-01

    The alloy composed of Al(95.53%), Zn(2.85%), Sn(0.515%), Ga(0.1%) and Sr(0.009%), with the weight percents in the parentheses, was prepared by melting, using Al(99.84%), a product of the Aluminium Plant-Podgorica, as the base material. The corrosion behaviour of this alloy was tested in relation to the behaviour of the base metals, by both open curcuit potential and polarization resistance methods, in aqueous solutions of both NaCl and Na2SO4, the concentration of which varied within the rang...

  10. Correlation between Corrosion Potential and Pitting Potential for AISI 304L Austenitic Stainless Steel in 3.5% NaCl Aqueous Solution

    OpenAIRE

    Neusa Alonso-Falleiros; Stephan Wolynec

    2002-01-01

    We investigated the effect of surface finish of two AISI 304L (UNS S30403) stainless steels on the corrosion potential (Ecorr) in 3.5% NaCl aqueous solution and its value was compared with the pitting potential (Ep) value and the type of anodic potentiodynamic curve obtained for determination of Ep in this solution. Five different surface finishes were examined. Ecorr and its standard deviation are strongly affected by the type of surface finish. Moreover, there are evidences of a linear corr...

  11. Effect of Indium Content on the Microstructure, Mechanical Properties and Corrosion Behavior of Titanium Alloys

    OpenAIRE

    Mi-Kyung Han; Jae-Bong Im; Moon-Jin Hwang; Bong-Jun Kim; Hae-Young Kim; Yeong-Joon Park

    2015-01-01

    Ti-xIn (x = 0, 5, 10, 15 and 20 wt%) alloys were prepared to investigate the effect of indium on the microstructure, mechanical properties, and corrosion behavior of titanium with the aim of understanding the relationship between phase/microstructure and various properties of Ti-xIn alloys. The Ti-xIn alloys exhibited a lamellar α-Ti structure at an indium content of up to 20 wt%. High-resolution TEM images of the Ti-xIn alloys revealed that all the systems contained a fine, acicular martensi...

  12. Corrosion Behavior of TiN Coated AISI D2 Steel

    OpenAIRE

    ÇEĞİL, Özkan; Şen, Şaduman

    2014-01-01

    In this study, the corrosion behaviors of nitride and titanium nitride (TiN) layers deposited on AISI D2 steel samples are reported. Steel was at first nitrided in a nitrogen and ammonia atmosphere at 575 °C for 8 h and then titanium nitride coating treatment was performed in the powder mixture consisting of ferro-titanium, ammonium chloride and alumina at 1000°C for 2h by pack diffusion coating. TiN coating layer thickness realized on the AISI D2 steel is 6,71 ± 0,9 μm. The hardness of TiN l...

  13. Steel Corrosion Inhibition by Acid Garlic Essential Oil as a Green Corrosion Inhibitor a nd Sorption Behavior

    OpenAIRE

    Afia, L.; Benali, O.; Salghi, R.; Ebenso, Eno E.; Jodeh, S.; Zougagh, M.; Hammouti, B.

    2014-01-01

    The aim of this work was to investigate the inhibition effect of acid garlic essential oil (GO oil) as an inhibitor on the corrosion of carbon steel in a 1M HCl solution at different temperatures by weight loss,electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. The GO oil acts as an effective corrosion inhibitor for carbon steel in a hydrochloric acid medium. The inhibition process is attributed to the formatio...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    International Nuclear Information System (INIS)

    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 H2SO4 at 45 .deg. C was taken as a standard corrosive solution in which Cl-, Fe3+ and Br- ion were added to investigate their effects. Acid concentration and temperature were also varied. Polarization behaviors of pure Ti, Ni, Mo and Ti2Ni 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 H2SO4 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. Fe3+ 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 Ti2Ni 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 + Ti2Ni occurs. Near pits, observed on a sensitized TiCode-12 specimen immersed in H2SO4, always found were β crystals in which Ni peak was detected by EDS

  16. Electrochemical Behavior of Spherical LiFePO4/C Nanomaterial in Aqueous Electrolyte, and Novel Aqueous Rechargeable Lithium Battery with LiFePO4/C anode

    International Nuclear Information System (INIS)

    We designed a novel aqueous rechargeable lithium battery with LiFePO4/C (LFP) and LiMn2O4/C (LMO) as the anode and cathode, respectively; then investigated the battery in Li2SO4 aqueous electrolyte. We also studied the electrochemical behavior of LFP in aqueous electrolyte using cyclic voltammetry (CV). The material exhibited excellent electrochemical performance in the aqueous electrolyte, including good oxidation/reduction reversibility and cycling stability; almost no decays were observable after 200CV cycles. The diffusion coefficients of Li ions through the interface between the liquid electrolyte and the solid LiFePO4 in terms of intercalation and deintercalation were 1.22 × 10−14 and 9.97 × 10−15 cm2/s, respectively. The material could be completely intercalated/deintercalated with Li ions in the aqueous electrolyte, indicating the excellent performance of LFP in an aqueous solution. Further, an aqueous rechargeable lithium battery (ARLB), which we fabricated using LFP as the anode and LMO as the cathode, also exhibited quite good performance in aqueous Li2SO4 solution: after 1,000 charge–discharge cycles at 2 C, the capacity loss was less than 30%, indicating that this type of ARLB has excellent cycling stability and may be promising for future research and application

  17. Prediction of Swelling Behavior of N-Isopropylacrylamide Hydrogels in Aqueous Solution of Sodium Chloride

    Institute of Scientific and Technical Information of China (English)

    许小平; 李忠琴; 黄兴华; 王绪绪; 付贤; HiitherAndreas; MaurerGerd

    2004-01-01

    In this paper, a model is presented to correlate and predict the swelling behavior of hydrogels in aqueous solutions of electrolytes. The model is a combination of VERS-model, "phantom network" theory and "free-volume" contribution. The VERS-model is used to calculate Gibbs excess energy; "phantom network" theory to describe the elastic properties of polymer network, and "free-volume" contribution to account for additional difference in the size of the species. To test the model, a series of N-isopropylacrylamide based hydrogels are synthesized by free radical polymerization in oxygen-free, deionized water at 25~C under nitrogen atmosphere. Then, the degree of swelling of all investigated gels as well as the partition of the solute between the gel phase and the surrounding coexisting liquid phase are measured in aqueous solution of sodium chloride. The model test demonstrates that the swelling behavior correlated and predicted by the model agrees with the experimental data within the experimental uncertainty. The phase transition appeared in the experiment, and the influences of the total mass fraction of polymerizable materials ξgel as well as the mole fraction of the crosslinking agent YCR on the swelling behavior of IPAAm-gels can also be predicted correctly. All these show the potential of such model for correlation and prediction of the swelling behavior of hydrogels in aqueous solutions of electrolytes.

  18. Crevice corrosion behaviour of titanium grades-2 and -12 in hot aqueous chloride solution - the effect of chloride concentration

    International Nuclear Information System (INIS)

    The crevice corrosion of Grades-2 (Ti-2) and -12 titanium (Ti-12) has been studied at a temperature of 150oC in solutions ranging in sodium chloride concentration from 0.27 mol·L-1 to 5.0 mol·L-1. A technique in which an artificially creviced electrode was coupled through a zero resistance ammeter to a large counter electrode was used to follow the potential of the crevice specimen and the coupled current due to oxygen reduction on the coupled electrode. The total amount of crevice corrosion which occurred on the specimen was estimated from weight change measurements. The depth of penetration due to crevice corrosion was measured using a combination of metallographic and image analysis techniques. Crevice corrosion of Ti-2 continued, without repassivation, until all the oxygen within the sealed pressure vessel system was exhausted. The weight change was proportional to the maximum depth of penetration and corrosion was observed to be quite generally distributed throughout the creviced area. Corrosion profiles (i.e., percentage of the creviced area corroded versus the depth of penetration) show a localized corrosion process preceding a more general corrosion front. The extent and rate of crevice propagation and the depth of maximum penetration, all decrease with increasing chloride concentration, but their dependence on this concentration is not major. By comparison, both the extent and rate of crevice corrosion of Ti-12 are dependent on chloride concentration increasing substantially for concentrations >0.5 mol·L-1 but decreasing again for concentrations >3.0 mol·L-1. However, at all chloride concentrations, the crevice repassivated before all the available oxygen was depleted; i.e., the extent of crevice corrosion is severely limited. Measurements of the depths of corrosion penetration show that, for Ti-12, penetration within the crevice occurs much more locally than for Ti-2. In fact, if a general corrosion front can be discerned at all, it is ∼10

  19. Magnetically induced electrodeposition of Zn–Ni alloy coatings and their corrosion behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Vaishaka R. [Electrochemistry Research Laboratory, Department of Chemistry, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar 575025, Mangalore, Karnataka (India); Bangera, Kasturi V. [Electrochemistry Research Laboratory, Department of Chemistry, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar 575025, Mangalore, Karnataka (India); Electrochemistry Research Laboratory, Department of Physics, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar, 575025, Mangalore, Karnataka (India); Hegde, A. Chitharanjan, E-mail: hegdeac@rediffmail.com [Electrochemistry Research Laboratory, Department of Chemistry, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar 575025, Mangalore, Karnataka (India)

    2013-11-15

    The less magnetic features of Zn–Ni alloy compared to Fe–Ni and Fe–Co alloys made it interesting to develop them under the influence of applied magnetic field. In this regard, the effects of a magnetic field (B) applied in a direction parallel and perpendicular to the nominal current, during electrodeposition process of Zn–Ni alloy have been investigated by means of X-ray diffraction and EDX analysis. The modification of crystal orientation by superimposition of a varying magnetic field is studied for alloys of constant nickel content (8 a %.), deposited at optimal current density (j) of 3.0 A dm{sup −2}. The effect of magnetic field on crystallographic orientation and hence the corrosion behaviors of the coatings were studied. The preferential orientations (101) and (002) of the zinc phase and (330) γ-Ni{sub 5}Zn{sub 21} phase are always favored to exist with parallel and perpendicular magnetic field. The preferential (321) γ-Ni{sub 5}Zn{sub 21} orientation is found to be the characteristic of perpendicular magnetic field. Further, Zn (100) orientation is found to be non-responsive to the effect of parallel magnetic field. The coatings developed using perpendicular magnetic field is more corrosion resistant compare to that for parallel magnetic field. This is attributed to the additional (321) γ-Ni{sub 5}Zn{sub 21} orientations. The changes in the phase structure of the coatings deposited at different magnetic field are attributed to the effect caused by the magnetic convection induced in the electrolytic solution, called MHD effect (magneto-hydrodynamic effect). The chemical composition of the alloy was found to be same in both natural and magnetically induced deposition due to constant Ni content in the bath. The variation in the surface morphology of the coatings was studied by scanning electron microscopy (SEM). The Zn–Ni alloy coating deposited at 0.8 T perpendicular B showed the highest corrosion resistance (with corrosion rate=0.26×10{sup

  20. The effect of fluoride ions on the corrosion behavior of pure titanium in 0.05 M sulfuric acid

    International Nuclear Information System (INIS)

    The corrosion behavior of pure titanium was investigated in 0.05 M H2SO4 solution with fluoride ions using various electrochemical techniques, such as open circuit potential (OCP), potentiodynamic polarization, electrochemical impedance measurements (EIS) and surface analyses via X-ray photoelectron spectroscopy (XPS). The results showed that titanium exhibited spontaneous passivation behavior in solutions with 0 M and 0.0005 M fluoride ions, compared with the active-passive behavior with 0.002 M ∼ 0.005 M. A critical value of the fluoride concentration was defined between 0.0005 M and 0.002 M. Multiple corrosion potentials were found under the conditions with fluoride ions higher than 0.002 M. The fluoride ion accelerated the corrosion of titanium via changing the structure of the film formed at OCP and destroying the protectiveness of the film, while it had few effects on cathodic hydrogen evolution reaction and passivation process at OCP. A corrosion mechanism associated with the fluoride ion was proposed. The corrosion behavior was well interpreted using the proposed mechanism and a criteria for the critical value of the fluoride concentration was also proposed

  1. Corrosion behavior of simulated high-level waste glass in the presence of calcium ion or metallic iron

    International Nuclear Information System (INIS)

    Static leach tests were conducted for simulated high-level waste (HLW) glass in CaCl2/Ca(OH)2 solutions to investigate the corrosion behavior of HLW glass under calcium-rich environments induced by cement based materials in geological repositories. Another series of leach tests were conducted in deionized water in the presence of iron to investigate the effects of iron over-pack on the glass corrosion. In CaCl2/Ca(OH)2 solutions, corrosion of the glass was inhibited during the test period compared to that in deionized water at the pH range of 6 - 11, while higher corrosion rate was observed in the initial stage of the test in Ca(OH)2 solution at the initial pH of 12. However, the corrosion rate dropped due to a formation of calcium silicates that covered the surface of the glass. Under the condition that iron exists in the vicinity of the glass, glass corrosion was enhanced compared to that without iron throughout the testing period. In addition, an alteration layer including iron and silicon was observed at the interface between the glass surface and the iron after the leach tests, and thermodynamic calculation showed that formation of an iron silicate was favored under the chemical compositions of the leachate during the period. The enhancement of the glass corrosion was assumed to be accompanied with transformation of silica, a glass network former, into iron silicates. (author)

  2. Influence of oxide scales on the corrosion behaviors of B510L hot-rolled steel strips

    Science.gov (United States)

    Man, Cheng; Dong, Chao-fang; Xue, Hui-bin; Xiao, Kui; Li, Xiao-gang; Qi, Hui-bin

    2016-07-01

    The influence of oxide scales on the corrosion behaviors of B510L hot-rolled steel strips was investigated in this study. Focused ion beams and scanning electron microscopy were used to observe the morphologies of oxide scales on the surface and cross sections of the hot-rolled steel. Raman spectroscopy and X-ray diffraction were used for the phase analysis of the oxide scales and corrosion products. The corrosion potential and impedance were measured by anodic polarization and electrochemical impedance spectroscopy. According to the results, oxide scales on the hot-rolled strips mainly comprise iron and iron oxides. The correlation between mass gain and test time follows a power exponential rule in the damp-heat test. The corrosion products are found to be mainly composed of γ-FeOOH, Fe3O4, α-FeOOH, and γ-Fe2O3. The contents of the corrosion products are different on the surfaces of the steels with and without oxide scales. The steel with oxide scales is found to show a higher corrosion resistance and lower corrosion rate.

  3. Adsorption behavior of caffeine as a green corrosion inhibitor for copper

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Fernando Silvio de [Grupo de Estudos de Processos Eletroquimicos e Eletroanaliticos, Departamento de Quimica, Universidade Federal de Santa Catarina, 88040-900, Florianopolis, SC (Brazil); Giacomelli, Cristiano [Departamento de Quimica, Universidade Federal de Santa Maria, Av. Roraima 1000, 97119-900, Santa Maria, RS (Brazil); Goncalves, Reinaldo Simoes [Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, 91501-970, Porto Alegre, RS (Brazil); Spinelli, Almir, E-mail: almir.spinelli@ufsc.br [Grupo de Estudos de Processos Eletroquimicos e Eletroanaliticos, Departamento de Quimica, Universidade Federal de Santa Catarina, 88040-900, Florianopolis, SC (Brazil)

    2012-12-01

    Electrochemical and impedance experiments were carried out to evaluate the corrosion behavior of copper in aerated 0.1 mol L{sup -1} H{sub 2}SO{sub 4} solutions in the presence of three xanthine derivatives with similar chemical structures. The corrosion rate of copper was found to increase in the presence of theophylline and theobromine and decrease in the presence of caffeine. The adsorption and inhibitory effect of caffeine on copper surfaces in aerated 0.1 mol L{sup -1} H{sub 2}SO{sub 4} solutions were then investigated in detail by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), contact angle measurements, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and fluorescence experiments. The data obtained indicate that caffeine behaves as a cathodic-type inhibitor adsorbing onto the copper surface according to the Temkin isotherm, with the negative Increment G Degree-Sign {sub ads} value of - 31.1 kJ mol{sup -1} signifying a spontaneous adsorption process. The corrosion inhibition efficiency increased with caffeine concentration in the range of 1.0-10.0 mmol L{sup -1}. Furthermore, the EIS results obtained at the open-circuit potential and surface analysis (SEM, EDS and fluorescence) clearly demonstrated the adsorption of the organic compound onto the copper electrode. The contact angle measurements revealed the formation of a hydrophobic protective film. This film covers up to 72% of the total active surface, acts as a protective barrier and prevents interaction between the metal, water and oxygen molecules. - Highlights: Black-Right-Pointing-Pointer We have investigated the adsorption and corrosion inhibition of caffeine on copper surfaces. Black-Right-Pointing-Pointer Caffeine behaves as a cathodic-type inhibitor. Black-Right-Pointing-Pointer Caffeine adsorbs onto copper surface according to Temkin isotherm. Black-Right-Pointing-Pointer There exists the formation of a hydrophobic film that acts as a

  4. Monte Carlo simulation of micro crack propagation behavior for stress corrosion cracking

    International Nuclear Information System (INIS)

    A calculation code of Monte Carlo simulation for micro crack propagation behavior of stress corrosion cracking has been developed. Improvements for micro crack growth rate treatments and stress distributions have been made. Calculated crack depth distributions were compared with the CBB test results for sensitized stainless steels and low carbon stainless steels with hardened layer. For sensitized stainless steels, the calculated crack depth distribution could well reproduce the CBB test results by taking into account crack growth rates obtained from experiments. For low carbon stainless steels, although considering stress distributions improved the overestimation of crack depths, the calculated crack depth distribution could not well reproduce the CBB test result. The results revealed that the effects of the crack growth rate and the stress distribution on micro crack propagation behaviors. (author)

  5. Corrosion of lined steel pressure equipment in aqueous H2SO4 service in a water treatment plant

    International Nuclear Information System (INIS)

    This paper details corrosion that occurred in two identical process pressure vessels during the first 4 years of operation. Corrosion occurred at branch nozzles, shell sections and structural attachments, which resulted in unplanned shutdowns and subsequent repairs. In situ vessel modifications were completed in order to reduce the number and frequency of corrosion sites. Design and fabrication considerations that should be assessed in detail during the initial design phase are presented. Issues that can increase the shutdown frequency while decreasing availability and the inspection interval are discussed. Recommendations are made that are intended to alert designers, fabricators, owner/operators and inspectors to fundamental issues associated with lined steel pressure equipment to be considered where such equipment is proposed in a corrosive process environment

  6. Comparative study on the corrosion behavior of Ti-Nb and TMA alloys for dental application in various artificial solutions

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Y.J. [The Affiliated Hospital of Stomatology, Chongqing Medical University, Chongqing 400015 (China); Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Wang, Y.B. [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Cheng, Y. [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Deng, F., E-mail: deng63@263.net [The Affiliated Hospital of Stomatology, Chongqing Medical University, Chongqing 400015 (China); Zheng, Y.F., E-mail: yfzheng@pku.edu.cn [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Wei, S.C. [The Affiliated Hospital of Stomatology, Chongqing Medical University, Chongqing 400015 (China); Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); School and Hospital of Stomatology, Peking University, Beijing 100081 (China)

    2011-04-08

    The corrosion behavior of Ti-Nb dental alloy in artificial saliva with and without the addition of lactic acid and sodium fluoride was investigated by electrochemical techniques, with the commercial Titanium-molybdenum alloy (TMA) as a comparison. The chemical composition, microstructure and constitutional phase were characterized via energy dispersive spectrometry, optical microscope and X-ray diffraction, meanwhile the open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization measurements were carried out to study the corrosion resistance of experimental alloys, with the corroded surface being further characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that the corrosion behavior of Ti-Nb alloy was similar to those TMA alloy samples in both artificial and acidified saliva solutions, whereas statistical analysis of the electrochemical impedance spectroscopy and polarization parameters showed Ti-Nb alloy exhibited better corrosion resistance in fluoridated saliva and fluoridated acidified saliva. SEM observation indicated that TMA alloy corroded heavily than Ti-Nb alloy in fluoride containing saliva. XPS surface analysis suggested that Nb{sub 2}O{sub 5} played an important role in anti-corrosion from the attack of fluoride ion. Based on the above finding, Ti-Nb alloy is believed to be suitable for the usage in certain fluoride treated dental works with excellent corrosion resistance in fluoride-containing oral media.

  7. Comparative study on the corrosion behavior of Ti-Nb and TMA alloys for dental application in various artificial solutions

    International Nuclear Information System (INIS)

    The corrosion behavior of Ti-Nb dental alloy in artificial saliva with and without the addition of lactic acid and sodium fluoride was investigated by electrochemical techniques, with the commercial Titanium-molybdenum alloy (TMA) as a comparison. The chemical composition, microstructure and constitutional phase were characterized via energy dispersive spectrometry, optical microscope and X-ray diffraction, meanwhile the open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization measurements were carried out to study the corrosion resistance of experimental alloys, with the corroded surface being further characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that the corrosion behavior of Ti-Nb alloy was similar to those TMA alloy samples in both artificial and acidified saliva solutions, whereas statistical analysis of the electrochemical impedance spectroscopy and polarization parameters showed Ti-Nb alloy exhibited better corrosion resistance in fluoridated saliva and fluoridated acidified saliva. SEM observation indicated that TMA alloy corroded heavily than Ti-Nb alloy in fluoride containing saliva. XPS surface analysis suggested that Nb2O5 played an important role in anti-corrosion from the attack of fluoride ion. Based on the above finding, Ti-Nb alloy is believed to be suitable for the usage in certain fluoride treated dental works with excellent corrosion resistance in fluoride-containing oral media.

  8. Corrosion behaviors of electroless plating Ni-P coatings deposited on magnesium alloys in artificial sweat solution

    International Nuclear Information System (INIS)

    Magnesium alloys are the optimum shell materials for electronic products. These electronic products inevitably contact with the hands of users, and then are corroded by the sweat solution mainly consisting of 0.1% urea, 0.5% NaCl and 0.5% lactic acid. Electroless plating Ni-P coatings can provide protection to the magnesium alloys shell. The corrosion behaviors of Ni-P coatings deposited on AZ91D magnesium alloys in artificial sweat solution were investigated by electrochemical tests and SEM observations. The results indicated that urea acted as corrosion inhibitor. The inhibiting effect of urea was reduced in NaCl solution or lactic acid solution. NaCl and lactic acid were the main corrosive mediums, and their synergistic effect can significantly accelerate the corrosion of Ni-P coatings

  9. Effect of Silica Ratio on the Corrosion Behavior of Nano-silica Potassium Silicate Coatings on Aluminum Alloy 2024

    Science.gov (United States)

    Bahri, H.; Danaee, I.; Rashed, G. R.; Zaarei, D.

    2015-02-01

    Nano-silica modified potassium silicate conversion coating was deposited in different nano-silica/potassium silicate ratios on the surface of 2024 aluminum alloy. The corrosion behavior of coatings was studied by electrochemical impedance spectroscopy, current transient, potentiodynamic polarization, and surface techniques. The ratio of nano-silica/potassium silicate was optimized in order to obtain higher corrosion protection. The experimental results indicated that with increasing nano-silica/potassium silicate ratio, the corrosion resistance of aluminum increases. Furthermore, the pitting corrosion probability of potassium silicate conversion coating decreased with increasing silica ratio. This can be related to the size of nano-silica particles and the ability to fill the pores in potassium silicate coating and reinforce the created siloxane bridges.

  10. Effect of Minor Alloying Elements on the Corrosion Behavior of Fe40Al in NaCl-KCl Molten Salts

    Directory of Open Access Journals (Sweden)

    G. Salinas

    2012-01-01

    Full Text Available The hot corrosion behavior of Fe40Al intermetallic alloyed with Ag, Cu, Li, and Ni (1–5 at.% in NaCl-KCl (1 : 1 M at 670°C, typical of waste gasification environments, has been evaluated by using polarization curves and weight loss techniques and compared with a 304-type stainless steel. Both gravimetric and electrochemical techniques showed that all different Fe40Al-base alloys have a much higher corrosion resistance than that for stainless steel. Among the different Fe40Al-based alloys, the corrosion rate was very similar among each other, but it was evident that the addition of Li decreased their corrosion rate whereas all the other elements increased it. Results have been explained in terms of the formation and stability of an external, protective Al2O3 layer.

  11. The effect of quench rate on the microstructure, mechanical properties, and corrosion behavior of U-6 Wt Pct Nb

    International Nuclear Information System (INIS)

    The effect of cooling rate on microstructure, mechanical behavior, corrosion resistance, and subsequent age hardenability is discussed. Cooling rates in excess of 20 Ks-1 cause the parent γ-phase to transform martensitically to a niobium supersaturated variant of the α-phase. This phase exhibits low hardness and strength, high ductility, good corrosion resistance, and age hardenability. As cooling rate decreases from 10 Ks-1 to 0.2 Ks-1, microstructural changes (consistent with spinodal decomposition) occur to an increasing extent. These changes produce increases in hardness and strength and decreases in ductility, corrosion resistance, and age hardenability. At cooling rates less than 0.2 Ks-1 the parent phase undergoes cellular decomposition to a coarse two-phase lamellar microstructure which exhibits intermediate strength and ductility, reduced corrosion resistance, and no age hardenability. An analysis of the cooling rates indicates that fully martensitic microstructures can be obtained in plates as thick as 50 mm

  12. On the Stress Corrosion Cracking and Hydrogen Embrittlement Behavior of Austenitic Stainless Steels in Boiling Saturated Magnesium Chloride Solutions

    OpenAIRE

    Alyousif, Osama M.; Rokuro Nishimura

    2012-01-01

    The stress corrosion cracking (SCC) and hydrogen embrittlement (HE) behaviors for types 304, 310, and 316 austenitic stainless steels were investigated in boiling saturated magnesium chloride solutions using a constant load method under different conditions including test temperature, applied stress, and sensitization. Both of type 304 and type 316 stainless steels showed quite similar behavior characteristics, whereas type 310 stainless steel showed a different behavior. The time to failure ...

  13. Effect of annealing treatment on microstructure evolution and the associated corrosion behavior of a super-duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Deng, B.; Jiang, Y.M.; Gao, J. [Department of Materials Science, Fudan University, Handan Street, Shanghai 200433 (China); Li, J., E-mail: jinli@fudan.edu.c [Department of Materials Science, Fudan University, Handan Street, Shanghai 200433 (China)

    2010-03-18

    The influence of annealing temperature on the pitting corrosion of a super-duplex stainless steel (SDSS) with mischmetal addition was investigated in chloride solution by critical pitting temperature (CPT) measurement. The corrosion behavior is strongly dependent on the microstructure, namely the presence of secondary phases, elemental partitioning behavior and volume fractions of ferrite and austenite. Based on CPT results and alloying rules, the optimal annealing temperature is determined as 1070 {sup o}C and a guideline for further development of improved SDSS is formulated.

  14. Studies on anodic corrosion of the electroplated CdSe in aqueous and non-aqueous media for photoelectrochemical cells and characterization of the electrode/electrolyte interface

    International Nuclear Information System (INIS)

    Polycrystalline n-CdSe thin films were prepared by electrodeposition at controlled current density on conducting substrates. The optical characteristics were determined through transmittance spectra. Scanning electron microscopy and atomic force microscopy were employed to study the morphology of the semiconductor (SC) surfaces. Chemical composition of the SC film was established by EDAX analysis. The n-CdSe/electrolyte junctions in water and non-aqueous solvents like acetonitrile (ACN), dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and propylene carbonate (PC) were characterized by Mott-Schottky analysis using frequency response analyzer. The stability of CdSe layers in water and in non-aqueous solvents was determined through anodic polarization studies. Anodic stripping voltammetry was employed to find out the dissoluted Cd2+ in solution. Photovoltage was measured under illuminated conditions using ferrocene-ferricenium couple in aqueous and non-aqueous solvents throughout the temperature range of 20-70 deg. C. The results are indicative of the potential use of the electrodeposited n-CdSe in selected non-aqueous medium for solar energy conversion by photoelectrochemical (PEC) devices

  15. Zinc Treatment Effects on Corrosion Behavior of Alloy 600 in High Temperature, Hydrogenated Water

    International Nuclear Information System (INIS)

    Trace levels of soluble zinc(II) ions (30 ppb) maintained in mildly alkaline, hydrogenated water at 260 C were found to reduce the corrosion rate of Alloy 600 (UNS N06600) by about 40% relative to a non-zinc baseline test [2]. Characterizations of the corrosion oxide layer via SEM/TEM and grazing incidence X-ray diffraction confirmed the presence of a chromite-rich oxide phase and recrystallized nickel. The oxide crystals had an approximate surface density of 3500 (micro)m-2 and an average size of 11 ± 5 nm. Application of X-ray photoelectron spectroscopy with argon ion milling, followed by target factor analyses, permitted speciated composition vs. depth profiles to be obtained. Numerical integration of the profiles revealed that: (1) alloy oxidation occurred non-selectively and (2) zinc(II) ions were incorporated into the chromite-rich spinel: (Zn0.55Ni0.3Fe0.15)(Fe0.25Cr0.75)2O4. Spinel stoichiometry places the trivalent ion composition in the single phase oxide region, consistent with the absence of the usual outer, ferrite-rich solvus layer. By comparison with compositions of the chromite-rich spinel obtained in the non-zinc baseline test, it is hypothesized that zinc(II) ion incorporation was controlled by the equilibrium for 0.55 Zn2+(aq) + (Ni0.7Fe0.3)(Fe0.3Cr0.7)2O4(s) (requilibrium) 0.40 Ni2+(aq) + 0.15 Fe2+(aq) + (Zn0.55Ni0.3Fe0.15)(Fe0.3Cr0.7)2O4(s). It is estimated that only 8% of the Ni(II) ions generated during non-selective oxidation of the alloy were retained as Ni(II) in the corrosion layer; the remainder either recrystallized to Ni(0) (38%) or were released to the aqueous phase (54%)

  16. Poly(ether imide)-silica hybrid coatings for tunable corrosion behavior and improved biocompatibility of magnesium implants.

    Science.gov (United States)

    Kang, Min-Ho; Jang, Tae-Sik; Jung, Hyun-Do; Kim, Sae-Mi; Kim, Hyoun-Ee; Koh, Young-Hag; Song, Juha

    2016-01-01

    Magnesium (Mg) and its alloys have gained considerable attention as a promising biomaterial for bioresorbable orthopedic implants, but the corrosion behavior of Mg-based implants is still the major issue for clinical use. In order to improve the corrosion stability and implant-tissue interfaces of these implants, methods for coating Mg have been actively investigated. In this study, poly(ether imide) (PEI)-silica hybrid material was coated on Mg, for the tunable degradation and enhanced biological behavior. Homogeneous PEI-silica hybrid materials with various silica contents were coated on Mg substrates without any cracks, where silica nanoparticles were well dispersed in the PEI matrix without significant particle agglomeration up the 30 vol% silica. The hybrid coatings maintained good adhesion strength of PEI to Mg. The corrosion rate of hybrid-coated Mg was increased along with the increment of the silica content, due to improved hydrophilicity of the hybrid coating layers. Moreover, the biocompatibility of the hybrid-coated Mg specimens was significantly improved, mainly due to the higher Mg ion concentrations associated with faster corrosion, compared to PEI-coated Mg. Therefore, PEI-silica hybrid systems have significant potential as a coating material of Mg for load-bearing orthopedic applications by providing tunable corrosion behavior and enhanced biological performance. PMID:27147643

  17. Effects of methane concentration on the controlled-impurity helium corrosion behavior of selected HTGR structural materials

    International Nuclear Information System (INIS)

    The corrosion behavior of candidate structural alloys in a series of three simulated advanced gas-cooled reactor environments at 9000C (16520F), with methane concentration varied, is discussed. The alloys investigated include three wrought alloys, Hastelloy X, Inconel 617, and Incoloy 800H; two cast superalloys, Rene 100 and IN 713; one centrifugally cast alloy, HK 40; and an oxide-dispersion-strengthened alloy, MA 754. Corrosion behavior was found to be strongly dependent upon both the alloy chemistry and the environment. Oxidation, carburization, and/or mixed behavior was observed depending upon the specific conditions. An equilibrium thermodynamics approach has been used to predict alloy behavior and explain observations relevant to the understanding of gas/metal interactions in reactor helium, which inherently contains small amounts of reactive impurity species. Carburization was identified as the primary corrosion phenomenon of concern, and detailed analyses were performed to determine the susceptibility and control of carburization reactions. The presence of alumina scales, containing small amounts of titanium, was found to be particularly effective in inhibiting carburization. Small variations in methane concentration have been shown to have a dramatic effect upon the oxidation potential and subsequent corrosion behavior of the alloy systems

  18. The role of microstructure and environment on the stress corrosion cracking behavior of structural materials in nuclear power plant environments

    International Nuclear Information System (INIS)

    Structural materials such as austenitic stainless steel and nickel base alloys can be susceptible to intergranular stress corrosion cracking (IGSCC) in high temperature, high purity water environments found in nuclear power plants. Both wrought and weld metal materials have been susceptible depending on the alloy composition and the microstructure present if conducive environmental conditions exist. This work focuses on the behavior of austenitic stainless steel in oxygenated high purity high temperature water environments. The susceptibility of both wrought and weld metals to the initiation of IGSCC is discussed. The recent efforts to quantify crack growth behavior of these materials is reviewed. Weld Metal toughness issues are discussed, as they pertain to continued operation with components containing stress corrosion cracks. The background behind materials and environmental solutions to stress corrosion cracking of power plant piping is presented

  19. Comparison of the corrosion behaviors of the glass-bonded sodalite ceramic waste form and reference HLW glasses

    International Nuclear Information System (INIS)

    A glass-bonded sodalite ceramic waste form is being developed for the long-term immobilization of salt wastes that are generated during spent nuclear fuel conditioning activities. A durable waste form is prepared by hot isostatic pressing (HIP) a mixture of salt-loaded zeolite powders and glass frit. A mechanistic description of the corrosion processes is being developed to support qualification of the CWF for disposal. The initial set of characterization tests included two standard tests that have been used extensively to study the corrosion behavior of high level waste (HLW) glasses: the Material Characterization Center-1 (MCC-1) Test and the Product Consistency Test (PCT). Direct comparison of the results of tests with the reference CWF and HLW glasses indicate that the corrosion behaviors of the CWF and HLW glasses are very similar

  20. Corrosion Behavior of Steel Reinforcement in Concrete with Recycled Aggregates, Fly Ash and Spent Cracking Catalyst

    Directory of Open Access Journals (Sweden)

    Hebé Gurdián

    2014-04-01

    Full Text Available The main strategy to reduce the environmental impact of the concrete industry is to reuse the waste materials. This research has considered the combination of cement replacement by industrial by-products, and natural coarse aggregate substitution by recycled aggregate. The aim is to evaluate the behavior of concretes with a reduced impact on the environment by replacing a 50% of cement by industrial by-products (15% of spent fluid catalytic cracking catalyst and 35% of fly ash and a 100% of natural coarse aggregate by recycled aggregate. The concretes prepared according to these considerations have been tested in terms of mechanical strengths and the protection offered against steel reinforcement corrosion under carbonation attack and chloride-contaminated environments. The proposed concrete combinations reduced the mechanical performance of concretes in terms of elastic modulus, compressive strength, and flexural strength. In addition, an increase in open porosity due to the presence of recycled aggregate was observed, which is coherent with the changes observed in mechanical tests. Regarding corrosion tests, no significant differences were observed in the case of the resistance of these types of concretes under a natural chloride attack. In the case of carbonation attack, although all concretes did not stand the highly aggressive conditions, those concretes with cement replacement behaved worse than Portland cement concretes.