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Sample records for temperature aqueous corrosion

  1. 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.

  2. 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)

  3. 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.

  4. 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.

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

    Directory of Open Access Journals (Sweden)

    H. Medhashree

    2017-03-01

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

  6. High temperature corrosion in gasifiers

    Directory of Open Access Journals (Sweden)

    Wate Bakker

    2004-03-01

    Full Text Available Several commercial scale coal gasification combined cycle power plants have been built and successfully operated during the last 5-10 years. Supporting research on materials of construction has been carried out for the last 20 years by EPRI and others. Emphasis was on metallic alloys for heat exchangers and other components in contact with hot corrosive gases at high temperatures. In this paper major high temperature corrosion mechanisms, materials performance in presently operating gasifiers and future research needs will be discussed.

  7. PULSED LASER DEPASSIVATION OF METALLIC ELECTRODES IN AQUEOUS CORROSIVE MEDIA

    OpenAIRE

    Oltra, R.; Indrianjafy, G.; Boquillon, J.

    1991-01-01

    A large amount of metallic materials in aqueous media (e.g. stainless steels, Nickel alloys ...) are protected from localized aqueous corrosion by thin oxide films grown in situ which passivate the metallic surfaces. The passivity can be disturbed by ionic breakdown or imposed mechanical breakdown of the protective film. In the conventional corrosion studies, a lot of techniques have been developed to simulate a local damage of the passive film which don't allow to reach the electrochemistry ...

  8. Generalized corrosion of nickel base alloys in high temperature aqueous media: a contribution to the comprehension of the mechanisms; Corrosion generalisee des alliages a base nickel en milieu aqueux a haute temperature: apport a la comprehension des mecanismes

    Energy Technology Data Exchange (ETDEWEB)

    Marchetti-Sillans, L

    2007-11-15

    In France, nickel base alloys, such as alloy 600 and alloy 690, are the materials constituting steam generators (SG) tubes of pressurized water reactors (PWR). The generalized corrosion resulting from the interaction between these alloys and the PWR primary media leads, on the one hand, to the formation of a thin protective oxide scale ({approx} 10 nm), and on the other hand, to the release of cations in the primary circuit, which entails an increase of the global radioactivity of this circuit. The goal of this work is to supply some new comprehension elements about nickel base alloys corrosion phenomena in PWR primary media, taking up with underlining the effects of metallurgical and physico-chemical parameters on the nature and the growth mechanisms of the protective oxide scale. In this context, the passive film formed during the exposition of alloys 600, 690 and Ni-30Cr, in conditions simulating the PWR primary media, has been analyzed by a set of characterization techniques (SEM, TEM, PEC and MPEC, XPS). The coupling of these methods leads to a fine description, in terms of nature and structure, of the multilayered oxide forming during the exposition of nickel base alloys in primary media. Thus, the protective part of the oxide scale is composed of a continuous layer of iron and nickel mixed chromite, and Cr{sub 2}O{sub 3} nodules dispersed at the alloy / mixed chromite interface. The study of protective scale growth mechanisms by tracers and markers experiments reveals that the formation of the mixed chromite is the consequence of an anionic mechanism, resulting from short circuits like grain boundaries diffusion. Besides, the impact of alloy surface defects has also been studied, underlining a double effect of this parameter, which influences the short circuits diffusion density in oxide and the formation rate of Cr{sub 2}O{sub 3} nodules. The sum of these results leads to suggest a description of the nickel base alloys corrosion mechanisms in PWR primary

  9. 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)

  10. 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.

  11. Low temperature corrosion in bark fuelled, small boilers

    Energy Technology Data Exchange (ETDEWEB)

    Lindau, Leif; Goldschmidt, Barbara

    2008-05-15

    A number of small (3-12 MW), new biofuel boiler plants in southern Sweden, and (at least) in Austria, have suffered a high (wastage of mm/yrs) corrosion rate on the low temperature boiler side. This problem has been investigated with respect to its occurrence and its character by contacts with operators, by plant inspections, and by analysis of cold-side deposits. The plants affected have low feed water temperatures (< 100 deg C). The plants fire most types of Swedish biofuel: chips, bark, hog fuel, and 'GROT' (=twigs and tops). The results found give basis for a hypothesis that the corrosion results from the presence of an aqueous phase in the deposits, this phase being stabilized by dissolved salts having high solubility. It then follows that for each salt, there is a critical relative humidity (calculated from the flue gas water partial pressure and the cooling surface temperature as is common practice among boiler engineers) for both the presence of the aqueous phase and the corrosion. Some critical single salts, ZnCl{sub 2} and CaCl{sub 2} have been identified, and they give critical 'relative humidities' of 5% and 18% respectively. These figures are a lower bound. The corresponding figure, derived from the practical experience and the reported plant operational data, is between 20 and 30%. Corrosion tests have been carried out by exposing an air-cooled probe in the flue gases at a 12 MW boiler at Saevelundsverket in Alingsaas, and the material wastage at different temperatures has been measured with a profilometer. The high corrosion rates were reproduced in the tests for high relative humidities. The corrosion rate was small and not measurable (<0.1 mm/year) for relative humidity <22%. The work shows by means of indirect evidence that the corrosion critical components are ZnCl{sub 2} and possibly CaCl{sub 2} as well. The practical engineering design criterion derived from the work is that the relative humidity (calculated from the flue

  12. Corrosion Inhibition of Mild Steel in Citric Acid by Aqueous Extract of Piper Nigrum L.

    Directory of Open Access Journals (Sweden)

    P. Matheswaran

    2012-01-01

    Full Text Available The inhibition efficiency (IE of an aqueous extract of Piper Nigrum L. in controlling corrosion of mild steel at pH 12 has been evaluated by weight loss method in the absence and presence of inhibitor in citric acid medium at different concentration. The result showed that the corrosion inhibition efficiency of these compounds was found to vary with the different concentration at two hour time interval at room temperature. Also, it was found that the corrosion inhibition behaviour of Piper Nigrum L. is greater in 2 N Citric acid than 1 N Citric acid medium. So Piper Nigrum L. can be used has a good inhibitor for preventing mild steel material which is used in many construction purpose.

  13. High Temperature Corrosion in Biomass Incineration Plants

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Maahn, Ernst emanuel; Gotthjælp, K.

    1997-01-01

    The aim of the project is to study the role of ash deposits in high temperature corrosion of superheater materials in biomass and refuse fire combined heat and power plants. The project has included the two main activities: a) A chemical characterisation of ash deposits collected from a major...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1964-07-01

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

  15. Fundamental aspects of high-temperature corrosion

    OpenAIRE

    Rapp, Robert

    1993-01-01

    Some recent considerations in three widely different aspects of high-temperature corrosion are summarized: 1) reactions at the metal/scale interface in support of scale growth; 2) mass transfer effects in the control of evaporation of volatile reaction products; and 3) the codeposition of multiple elements for diffusion coatings using halide-activated cementation packs. The climb of misfit edge dislocations from the metal/scale interface can achieve the annihilation of vacancies associated wi...

  16. Fe sub 3 Al-type iron aluminides: Aqueous corrosion properties in a range of electrolytes and slow-strain-rate ductilities during aqueous corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Buchanan, R.A.; Kim, J.G. (Tennessee Univ., Knoxville, TN (United States). Dept. of Materials Science and Engineering)

    1992-08-01

    The Fe{sub 3}Al-type iron aluminides have undergone continued development at the Oak Ridge National Laboratory for enhancement of mechanical and corrosion properties. Improved alloys and thermomechanical processing methods have evolved. The overall purpose of the project herein described was to evaluate the aqueous corrosion properties of the most recent alloy compositions in a wide range of possibly-aggressive solutions and under several different types of corrosion-test conditions. The work supplements previous aqueous-corrosion studies on iron aluminides by the present authors. Four stages of this one-year aqueous-corrosion investigation are described. First the corrosion properties of selected iron aluminides were evaluated by means of electrochemical tests and longer-time immersion tests in a range of acidic, basic and chloride solutions. Theses tests were performed under non-crevice conditions, i.e. the specimens were not designed to contain crevice geometries. Second, the iron-aluminide alloy that proved most resistance to chloride-induced localized corrosion under non-crevice conditions was further evaluated under more-severe crevice conditions by electrochemical and immersion testing. Third, in order to study the relative roles of Fe, Al, Cr and Mo in the formation of passive films, the chemical compositions of passive films were determined by X-ray photoelectron spectroscopy (XPS). And fourth, in order to study aqueous-corrosion effects on the ductilities of iron aluminides as related to hydrogen embrittlement and/or stress-corrosion cracking, slow-strain-rate corrosion (SSRC) tests were conducted over a range of electrochemical potentials.

  17. Fe{sub 3}Al-type iron aluminides: Aqueous corrosion properties in a range of electrolytes and slow-strain-rate ductilities during aqueous corrosion

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-08-01

    The Fe{sub 3}Al-type iron aluminides have undergone continued development at the Oak Ridge National Laboratory for enhancement of mechanical and corrosion properties. Improved alloys and thermomechanical processing methods have evolved. The overall purpose of the project herein described was to evaluate the aqueous corrosion properties of the most recent alloy compositions in a wide range of possibly-aggressive solutions and under several different types of corrosion-test conditions. The work supplements previous aqueous-corrosion studies on iron aluminides by the present authors. Four stages of this one-year aqueous-corrosion investigation are described. First the corrosion properties of selected iron aluminides were evaluated by means of electrochemical tests and longer-time immersion tests in a range of acidic, basic and chloride solutions. Theses tests were performed under non-crevice conditions, i.e. the specimens were not designed to contain crevice geometries. Second, the iron-aluminide alloy that proved most resistance to chloride-induced localized corrosion under non-crevice conditions was further evaluated under more-severe crevice conditions by electrochemical and immersion testing. Third, in order to study the relative roles of Fe, Al, Cr and Mo in the formation of passive films, the chemical compositions of passive films were determined by X-ray photoelectron spectroscopy (XPS). And fourth, in order to study aqueous-corrosion effects on the ductilities of iron aluminides as related to hydrogen embrittlement and/or stress-corrosion cracking, slow-strain-rate corrosion (SSRC) tests were conducted over a range of electrochemical potentials.

  18. Corrosion behavior of a superduplex stainless steel in chloride aqueous solution

    Science.gov (United States)

    Dabalà, Manuele; Calliari, Irene; Variola, Alessandra

    2004-04-01

    Super duplex stainless steels (SDSS) have been widely used as structural materials for chemical plants (especially in those engaged in phosphoric acid production), in the hydrometallurgy industries, and as materials for offshore applications due to their excellent corrosion resistance in chloride environments, compared with other commercial types of ferritic stainless steels. These alloys also possess superior weldability and better mechanical properties than austenitic stainless steels. However, due to their two-phase structure, the nature of which is very dependent on their composition and thermal history, the behavior of SDSS regarding localized corrosion appears difficult to predict, especially in chloride environments. To improve their final properties, the effect of the partition of the alloying elements between the two phases, and the composition and microstructure of each phase are the key to understanding the localized corrosion phenomena of SDSS. This paper concerns the effects of the SDSS microstructure and heat treatment on the SDSS corrosion resistance in aqueous solutions, containing different amounts of NaCl at room temperature.

  19. Effect of temperature on structure and corrosion resistance for ...

    Indian Academy of Sciences (India)

    Moreover, cracks were observed by SEM in coating surface and interface at the plating temperature of 90 ∘ C. Coating corrosion resistance is highly dependent on temperature according to polarization curves. The optimum temperature isfound to be 80 ∘ C and the possible reasons of corrosion resistance for NiWP coating ...

  20. Erosion–corrosion and corrosion properties of DLC coated low temperature Erosion–corrosion and corrosion properties of DLC coated low temperature

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Christiansen, Thomas; Hilbert, Lisbeth Rischel

    2009-01-01

    of AISI 316 as substrate for DLC coatings are investigated. Corrosion and erosion–corrosion measurements were carried out on low temperature nitrided stainless steel AISI 316 and on low temperature nitrided stainless steel AISI 316 with a top layer of DLC. The combination of DLC and low temperature...... nitriding dramatically reduces the amount of erosion–corrosion of stainless steel under impingement of particles in a corrosive medium.......Lowtemperature nitriding of stainless steel leads to the formation of a surface zone of so-called expanded austenite, i.e. by dissolution of large amounts of nitrogen in solid solution. In the present work the possibility of using nitrogen expanded austenite “layers” obtained by gaseous nitriding...

  1. High Temperature Corrosion in Biomass-Fired Boilers

    DEFF Research Database (Denmark)

    Henriksen, Niels; Montgomery, Melanie; Hede Larsen, Ole

    2002-01-01

    condense on superheater components. This gives rise to specific corrosion problems not previously encountered in coal-fired power plants. The type of corrosion attack can be directly ascribed to the composition of the deposit and the metal surface temperature. To avoid such high corrosion rates, woodchip...... has also been utilised as a fuel. Combustion of woodchip results in a smaller amount of ash, and potassium and chlorine are present in lesser amounts. However, significant corrosion rates were still seen. A case study of a woodchip fired boiler is described. The corrosion mechanisms in both straw...

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

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  3. Effect of temperature on structure and corrosion resistance for ...

    Indian Academy of Sciences (India)

    corrosion resistance becomes lower. Probably, there is. Figure 6. Relationship between temperature and the natural cor- rosion potential of NiWP coating in the 3.5% NaCl solution. With the increase in the bath temperature, natural corrosion potential showed parabola change, increased first and then decreased, natural.

  4. Corrosion behavior of Mg/graphene composite in aqueous electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Selvam, M. [Centre for Nano Science and Technology, KS Rangasamy College of Technology, Tiruchengode, 637215, Tamil Nadu (India); Saminathan, K., E-mail: ksaminath@gmail.com [Centre for Nano Science and Technology, KS Rangasamy College of Technology, Tiruchengode, 637215, Tamil Nadu (India); Siva, P. [Centre for Nano Science and Technology, KS Rangasamy College of Technology, Tiruchengode, 637215, Tamil Nadu (India); Saha, P. [Department of Ceramic Engineering, National Institute of Technology, Rourkela, India-769008 (India); Rajendran, V. [Centre for Nano Science and Technology, KS Rangasamy College of Technology, Tiruchengode, 637215, Tamil Nadu (India)

    2016-04-01

    In the present work, the electrochemical corrosion behavior of magnesium (Mg) and thin layer graphene coated Mg (Mg/graphene) are studied in different salt electrolyte such as NaCl, KCl and Na{sub 2}SO{sub 4}. The phase structure, crystallinity, and surface morphology of the samples are investigated using X-ray diffraction (XRD) analysis, scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDAX), and Raman spectroscopy techniques. The electrochemical corrosion behavior of the Mg and graphene coated Mg are also investigated using Electrochemical Impedance Spectroscopy (EIS) analysis. The tafel plot reveals that the corrosion of Mg drastically drops when coated with thin layer graphene (Mg/graphene) compared to Mg in KCl electrolyte. Moreover, the EIS confirms that Mg/graphene sample shows improve corrosion resistance and lower corrosion rate in KCl solution compare to all other electrolytes studied in the present system. - Highlights: • The corrosion behavior of magnesium alloy (AZ91) was investigated in three different electrolyte solution. • To study the anti-corrosion behavior of graphene coated with magnesium alloy. • To improve the corrosion resistance for magnesium alloy. • Nyquist plots confirms that MgG shows better corrosion resistance and lower corrosion rate in KCl solution.

  5. High Temperature Corrosion on Biodust Firing

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi

    The high content of alkali metals and chlorine in biomass gives rise to fouling/slagging and corrosion of heat exchange components, such as superheaters, in biomass fired power plants. Increasing the lifetime of these components, and in addition, preventing unwarranted plant shutdowns due...... to their failure, requires understanding of the complex corrosion mechanisms, as well as development of materials that are resistant to corrosion under biomass firing conditions, thereby motivating the current work. To understand the mechanisms of corrosion attack, comprehensive analysis of corrosion products...... was necessary. In the present work, two complementary methodologies based on analysis of cross sections and plan views were applied to achieve comprehensive characterization of corrosion products. The suitability of these methods for both laboratory scale and full scale corrosion investigations was demonstrated...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-06-15

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

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

    Directory of Open Access Journals (Sweden)

    Jee-Hyung Sim

    2017-06-01

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

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

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey; Petrushina, Irina; Christensen, Erik

    2011-01-01

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

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    Different corrosion resistant stainless steels, nickel-based alloys, pure nickel, Ta-coated stainless steel (AISI 316L), niobium, platinum and gold rods were evaluated as possible materials for use in the intermediate temperature (200-400 °C) acidic water electrolysers. The corrosion resistance w...

  10. A system for characterizing Mg corrosion in aqueous solutions using electrochemical sensors and impedance spectroscopy.

    Science.gov (United States)

    Doepke, Amos; Kuhlmann, Julia; Guo, Xuefei; Voorhees, Robert T; Heineman, William R

    2013-11-01

    Understanding Mg corrosion is important to the development of biomedical implants made from Mg alloys. Mg corrodes readily in aqueous environments, producing H2, OH- and Mg2+. The rate of formation of these corrosion products is especially important in biomedical applications where they can affect cells and tissue near the implant. We have developed a corrosion characterization system (CCS) that allows realtime monitoring of the solution soluble corrosion products OH-, Mg2+, and H2 during immersion tests commonly used to study the corrosion of Mg materials. Instrumentation was developed to allow the system to also record electrochemical impedance spectra simultaneously in the same solution to monitor changes in the Mg samples. We demonstrated application of the CCS by observing the corrosion of Mg (99.9%) in three different corrosion solutions: NaCl, HEPES buffer, and HEPES buffer with NaCl at 37°C for 48 h. The solution concentrations of the corrosion products measured by sensors correlated with the results using standard weight loss measurements to obtain corrosion rates. This novel approach gives a better understanding of the dynamics of the corrosion process in realtime during immersion tests, rather than just providing a corrosion rate at the end of the test, and goes well beyond the immersion tests that are commonly used to study the corrosion of Mg materials. The system has the potential to be useful in systematically testing and comparing the corrosion behavior of different Mg alloys, as well as protective coatings. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  11. 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.

  12. High temperature corrosion during biomass firing: improved understanding by depth resolved characterisation of corrosion products

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2015-01-01

    The high temperature corrosion of an austenitic stainless steel (TP 347H FG), widely utilised as a superheater tube material in Danish power stations, was investigated to verify the corrosion mechanisms related to biomass firing. KCl coated samples were exposed isothermally to 560 degrees C...... changes within the near surface region (covering both the deposit and the steel surface). Such cross-section analysis was further complemented by plan view investigations (additionally involving X-ray diffraction) combined with removal of the corrosion products. Improved insights into the nature...... of the corrosion products as a function of distance from the deposit surface were revealed through this comprehensive characterisation. Corrosion attack during simulated straw-firing conditions was observed to occur through both active oxidation and sulphidation mechanisms....

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

    Indian Academy of Sciences (India)

    Administrator

    Keywords. Bronze; inhibitors; quinoxalin compounds; chloride solution; electrochemical studies. 1. Introduction. Heterocyclic organic compounds containing nitrogen, sulphur or oxygen atoms are often used to protect copper and copper alloy metals from corrosion. Among them, azoles compounds like triazoles, imidazoles ...

  14. The aqueous corrosion behavior of technetium - Alloy and composite materials

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-01

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

  15. Deposition and high temperature corrosion in a 10 MW straw

    DEFF Research Database (Denmark)

    Michelsen, Hanne Philbert; Frandsen, Flemming; Dam-Johansen, Kim

    1998-01-01

    Deposition and corrosion measurements were conducted at a 10 MW wheat straw fired stoker boiler used for combined power and heat production. The plant experiences major problems with deposits on the heat transfer surfaces, and test probes have shown enhanced corrosion due to selective corrosion...... for metal temperatures above 520 C. Deposition measurements carried out at a position equal to the secondary superheater showed deposits rich in potassium and chlorine and to a lesser extent in silicon, calcium, and sulfur. Potassium and chlorine make up 40-80 wt% of the deposits. Mechanisms of deposit...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-12-31

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

  17. 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.

  18. High temperature and stress corrosion cracking of 310S austenitic stainless steel in wet chloride corrosive environment

    Directory of Open Access Journals (Sweden)

    T. Pornpibunsompop

    2018-01-01

    Full Text Available High temperature corrosion and stress corrosion cracking of 310S austenitic stainless steel in wet chloride environment at a high temperature was investigated. The result showed that high temperature corrosion products mostly consisted of ferrous oxides and chromium oxides. Chloride ions attacked a chromium passive film and strongly reacted with iron and chromium. As a result of metal chlorides being volatized, tunnel of pores inside corrosion layer existed. Intergranular stress corrosion cracking was observed. The oxide originated on surface could act as a crack initiator and a crack propagation would progress along grain boundaries and particularly along tunnel of pores.

  19. Temperature dependence of the surface enhanced raman spectroelectrochemistry of iron in aqueous solutions.

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, L. J.; Melendres, C. A.; Chemical Engineering

    1996-06-01

    The effect of temperature on the composition of the corrosion film on iron in aqueous sodium hydroxide and borate solutions was investigated using surface enhanced Raman spectroelectrochemistry (SERS). Fe(OH){sub 2} and Fe{sub 3}O{sub 4} were observed in the prepassivation region, while Fe{sub 3}O{sub 4} and FeOOH accounted for most of the passivated film at 25, 60 and 95 C. Fe(OH){sub 2} was found to be a stable component of the corrosion film on iron at 95 C, which is contrary to recently published theoretical calculations.

  20. 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.

  1. Low temperature corrosion in bark fuelled, small boilers; Laagtemperaturkorrosion i barkeldade, mindre pannor

    Energy Technology Data Exchange (ETDEWEB)

    Lindau, Leif; Goldschmidt, Barbara [Sycon Energikonsult AB, Malmoe (Sweden)

    2002-04-01

    A number of small (3-12 MW), new biofuel boiler plants in South Sweden, and (at least) in Austria, have suffered a high (wastage of mm/yrs.) corrosion rate on the low temperature boiler side. This problem has been investigated with respect to its occurrence and its character by contacts with operators, by plant inspections, and by analysis of cold side deposits. The plants affected have low feed water temperatures (< 100 deg C ). The plants fire most types of Swedish biofuel: chips, bark, hog fuel, and 'GROT'(=twigs and tops). The results found give basis for a hypothesis that the corrosion results from the presence of an aqueous phase in the deposits, this phase being stabilized by dissolved salts having high solubility. It then follows that for each salt, there is a critical relative humidity (calculated from the flue gas water partial pressure and the cooling surface temperature as is common practice among boiler engineers) for both the presence of the aqueous phase and the corrosion. Some critical single salts, ZnC12 and CaC12 have been identified, and they give critical 'relative humidities' of 5% and 18% respectively. These figures are a lower bound. The corresponding figure, derived from the practical experience and the reported plant operational data, is between 20 and 30%. Corrosion tests have been carried out by exposing an air-cooled probe in the fluegases at a 12 MW boiler at Saevelundsverket in Alingsaas, and the material wastage at different temperatures has been measured with a profilometer. The high corrosion rates were reproduced in the tests for high relative humidities. The corrosion rate was small and not measurable (<0.1 mm/yr) for relative humidity < 22%. The work shows by means of indirect evidence that the corrosion critical components are ZnCl{sub 2} and possibly CaCl{sub 2} as well. The practical engineering design criterion derived from the work is that the relative humidity (calculated from the flue gas water partial

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

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey

    2010-01-01

    Different types of corrosion resistant stainless steels, Ni-based alloys as well as titanium and tantalum were evaluated as a possible metallic bipolar plate and construction material with respect to corrosion resistance under simulated conditions corresponding to the conditions in high temperature...... proton exchange membrane (PEM) water electrolysers (HTPEMWE). All samples were exposed to anodic polarisation in 85% phosphoric acid electrolyte solution. Platinum and gold plates were tested for the valid comparison. Steady-state voltammetry was used in combination with scanning electron microscopy...... and energy-dispersive X-ray spectroscopy. Results show that stainless steels are the most inclined to corrosion under high anodic polarization. Among alloys, Ni-based showed the highest corrosion resistance under conditions, simulating HTPEMWE. In particular, Inconel625 is the most promising alloy...

  3. Corrosion behaviour of iron and AISI 304 stainless steel in tungstate aqueous solutions containing chloride

    Directory of Open Access Journals (Sweden)

    Azambuja Denise S.

    2003-01-01

    Full Text Available The corrosion behavior of iron and AISI 304 stainless steel in aqueous tungstate solutions containing chloride ion was investigated by cyclic voltammetry, open circuit measurements and impedance spectroscopy. The obtained results point out that the inhibitive performance of tungstate depends on the presence of dissolved oxygen, being strongly related to the adsorption of this anion on the surface of the electrode. Under anodic polarization, at low sweep rate and electrode rotation the passive film is more stable and the corrosion rate decreases. At the open circuit potential, the EIS data have clearly demonstrated that for longer immersion times the tungstate inhibitive action is considerably improved.

  4. Corrosion of High Chromium Ferritic/Martensitic Steels in High Temperature Water. a Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, P.; Lapena, J.; Blazquez, F. [Ciemat, Madrid (Spain)

    2000-07-01

    Available literature concerning corrosion of high-chromium ferritic/martensitic steels in high temperature water has been reviewed. The subjects considered are general corrosion, effect of irradiation on corrosion, stress corrosion cracking (SCC) and irradiation-assisted stress corrosion cracking (IASCC). In addition some investigations about radiation induced segregation (RIS) are shown in order to know the compositional changes at grain boundaries of these alloys and their influence on corrosion properties. The data on general corrosion indicate moderate corrosion rates in high temperature water up to 350 degree centigree. Considerably larger corrosion rates were observed under neutron irradiation. The works concerning to the behaviour of these alloys to stress corrosion cracking seem to conclude that in these materials is necessary to optimize the temper temperature and to carry out the post-weld heat treatments properly in order to avoid stress corrosion cracking. (Author) 40 refs.

  5. High temperature corrosion in straw-fired power plants: Influence of steam/metal temperature on corrosion rates for TP347H

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Biede, O; Larsen, OH

    2002-01-01

    The corrosion in straw-fired boilers has been investigated at various straw-fired power plants in Denmark. Water/air-cooled probes, a test superheater and test sections removed from the actual superheater have been utilised to characterise corrosion and corrosion rates. This paper describes...... the corrosion rates measured for the TP347H type steel. The corrosion morphology at high temperature consists of grain boundary attack and selective attack of chromium. The corrosion rate increases with calculated metal temperature (based on steam temperature), however there is great variation within...... these results. In individual superheaters, there are significant temperature variations i.e. higher temperature in middle banks compared to the outer banks, higher temperature in leading tubes, which have a high impact on corrosion. In a single loop the assumption that heat uptake (and heat flux) is linear...

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

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Oxidation and hot corrosion are serious problems in aircraft, marine, industrial, and land-base gas turbines. It is because of the usage of wide range of fuels coupled with increased operating temperatures, which leads to the degradation of turbine engines. To obviate these problems, superalloys, viz. Superni 75,.

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

    Indian Academy of Sciences (India)

    Oxidation and hot corrosion are serious problems in aircraft, marine, industrial, and land-base gas turbines. It is because of the usage of wide range of fuels coupled with increased operating temperatures, which leads to the degradation of turbine engines. To obviate these problems, superalloys, viz. Superni 75, Superni ...

  8. High-temperature corrosion resistance of ceramics and ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.

    1996-06-01

    Ceramics and ceramic composites offer the potential to operate fossil energy systems at the higher temperatures necessary for improved energy efficiency and better environmental control. However, because many fossil fuel-derived processes contain sulfur, chlorine, and carbon, as well as oxygen, degradation from high-temperature corrosion and environmental effects arising from reactions of solids with gases and condensable products is a common life-determining factor in operating systems. Ceramic-based products are not immune to such degradation; adequate corrosion resistance must be assured to exploit the technical and economic potential of such materials. This is normally accomplished by using stable, sound oxides that exist in their bulk form, that naturally grow as surface layers upon exposure to an oxidizing environment, or that are deposited as a coating on a susceptible material. It is therefore important to examine the critical issues with respect to more environmental stability of ceramics that have the potential to be corrosion resistant in particular fossil environments. Key aspects include not only chemical compatibility, but the influence of the environment on the mechanical behavior of the ceramic materials. In addition, for coatings, the mechanical reliability of the ceramic is a key issue in that an otherwise corrosion-resistant surface layer must remain sound and adherent in order to provide protection to the underlying substrate. The purpose of this work is to support the development of advanced ceramics and ceramic composites for applications in fossil environments by examining critical issues related to high-temperature corrosion resistance. More specifically, the overall objective of this task is to examine the chemical compatibility and reliability of potentially corrosion-resistant ceramics being developed as protective overcoats and/or structural materials as parts of other work elements funded by the AR&TD Program.

  9. Corrosion Behavior of L80Steel in Different Temperature and Sulfur Content

    Science.gov (United States)

    Qiu, Zhichao; Xiong, Chunming; Yi, Ran; Ye, Zhengrong

    2017-10-01

    To understand the corrosion behavior of L80 steel in different temperature and sulfur content, the experiment which simulated the downhole corrosive environment was conducted. From the experiment result, when other factors were constant, the lowest corrosion rate was appeared when the temperature was 90°C. The influence of sulfur was complex. When temperature was low, the corrosion rate was decreased with the increase of sulfur content and the experimental result was opposite when temperature was high.

  10. 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.

  11. Effects of Temperature and Corrosion Potential on SCC

    Science.gov (United States)

    Andresen, Peter L.; Seeman, Russell A.

    This study reinforces the expectation that a consistent benefit of low corrosion potential is achievable at intermediate temperatures associated with BWR start up. Such low corrosion potentials can probably only be achieved using NobleChem™ and injection of H2 or other reductants such as hydrazine or carbohydrazide because very low residual levels of O2 can elevate the corrosion potential. The high growth rates that occur during start up merit mitigation, although this study did not find growth rates that were orders of magnitude higher than at 288 °C. However, this study did not attempt to simulate all aspects of start up, especially the sources of dynamic strain such as differential thermal expansion, which can be estimated by are not known.

  12. 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.

  13. High temperature corrosion of separator materials for MCFC

    Energy Technology Data Exchange (ETDEWEB)

    Yanagida, Masahiro; Tanimoto, Kazumi; Kojima, Toshikatsu [Osaka National Research Institute (Japan)] [and others

    1996-12-31

    The Molten Carbonate Fuel Cell (MCFC) is one of promising high efficiency power generation devices with low emission. Molten carbonate used for its electrolyte plays an important role in MCFC. It separates between anode and cathode gas environment and provides ionic conductivity on MCFC operation. Stainless steel is conventionally used as separator/current collector materials in MCFC cathode environment. As corrosion of the components of MCFC caused by the electrolyte proceeds with the electrolyte consumption, the corrosion in the MCFC is related to its performance and life. To understand and inhibit the corrosion in the MCFC is important to realize MCFC power generation system. We have studied the effect of alkaline earth carbonate addition into carbonate on corrosion of type 316L stainless steel. In this paper, we describe the effect of the temperature on corrosion behavior of type 316L stainless steel with carbonate mixture, (Li{sub 0.62}K{sub 0.38}){sub 2}CO{sub 3}, under the cathode environment in out-of-cell test.

  14. 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

  15. Aromatic quinoxaline as corrosion inhibitor for bronze in aqueous ...

    Indian Academy of Sciences (India)

    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 ... BP 1014, Avenue Ibn Battouta, Rabat, Morocco; Laboratoire de Chimie Organique et d'Etudes Physico-chimiques, Ecole Normale Supérieure de Takaddoum, BP ...

  16. 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)

  17. Corrosion resistant coatings suitable for elevated temperature application

    Science.gov (United States)

    Chan, Kwai S [San Antonio, TX; Cheruvu, Narayana Sastry [San Antonio, TX; Liang, Wuwei [Austin, TX

    2012-07-31

    The present invention relates to corrosion resistance coatings suitable for elevated temperature applications, which employ compositions of iron (Fe), chromium (Cr), nickel (Ni) and/or aluminum (Al). The compositions may be configured to regulate the diffusion of metals between a coating and a substrate, which may then influence coating performance, via the formation of an inter-diffusion barrier layer. The inter-diffusion barrier layer may comprise a face-centered cubic phase.

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

    Science.gov (United States)

    Xu, Wenlong; Hu, Yuanyuan; Bao, Wenda; Xie, Xiaoyu; Liu, Yiran; Song, Aixin; Hao, Jingcheng

    2017-03-01

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

  19. Potential high temperature corrosion problems due to co-firing of biomass and fossil fuels

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Vilhelmsen, T.; Jensen, S.A.

    2008-01-01

    Over the past few years, considerable high temperature corrosion problems have been encountered when firing biomass in power plants due to the high content of potassium chloride in the deposits. Therefore, to combat chloride corrosion problems cofiring of biomass with a fossil fuel has been....... However, the most significant corrosion attack was sulphidation attack at the grain boundaries of 18-8 steel after 3 years exposure. The corrosion mechanisms and corrosion rates are compared with biomass firing and coal firing. Potential corrosion problems due to co-firing biomass and fossil fuels...

  20. Potential high temperature corrosion problems due to co-firing of biomass and fossil fuels

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Vilhelmsen, T.; Jensen, S.A.

    2007-01-01

    Over the past years, considerable high temperature corrosion problems have been encountered when firing biomass in power plants due to the high content of potassium chloride in the deposits. Therefore to combat chloride corrosion problems co-firing of biomass with a fossil fuel has been undertaken...... significant corrosion attack was due to sulphidation attack at the grain boundaries of 18-8 steel after 3 years exposure. The corrosion mechanisms and corrosion rates are compared with biomass firing and coal firing. Potential corrosion problems due to co-firing biomass and fossil fuels are discussed....

  1. Stress Corrosion Cracking of Zircaloy-4 in Halide Solutions: Effect of Temperature

    Directory of Open Access Journals (Sweden)

    Farina S.B.

    2002-01-01

    Full Text Available Zircaloy-4 was found to be susceptible to stress corrosion cracking in 1 M NaCl, 1 M KBr and 1 M KI aqueous solutions at potentials above the pitting potential. In all the solutions tested crack propagation was initially intergranular and then changed to transgranular. The effect of strain rate and temperature on the SCC propagation was investigated. An increase in the strain rate was found to lead to an increase in the crack propagation rate. The crack propagation rate increases in the three solutions tested as the temperatures increases between 20 and 90 °C. The Surface-Mobility SCC mechanism accounts for the observation made in the present work, and the activation energy predicted in iodide solutions is similar to that found in the literature.

  2. Corrosion of Alloy 617 in high-temperature gas environments

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Tsung-Kuang [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Chang, Hao-Ping [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Wang, Mei-Ya, E-mail: meywang@mx.nthu.edu.tw [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 300, Taiwan (China); Yuan, Trai [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Kai, Ji-Jung [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan (China)

    2014-05-01

    High-temperature gas-cooled reactors (HTGRs) with helium gas as the primary coolant have been considered as one type of the Generation IV nuclear power reactor systems. Several nickel-based superalloys, including Alloy 617, are potential structural materials to serve as pressure boundary components, such as the intermediate heat exchanger (IHX) in an HTGR. Impurities in a helium coolant, such as H{sub 2}O and O{sub 2}, can interact with structural materials at working temperatures of >900 °C, leading to serious degradation on these materials. In addition, defects in IHX surface coatings would allow these species to reach and interact with the external surfaces of these components, leading to similar or even more serious degradation. In this study we investigated the oxidation behavior of Alloy 617 in high-temperature, gaseous environments with various levels of O{sub 2} and H{sub 2}O. A series of general corrosion tests were conducted at test temperatures of 650 °C, 750 °C, 850 °C and 950 °C under various coolant compositions of dry air, 1% O{sub 2}, 10% relative humidity (RH), and 50% RH. Preliminary results showed that the surface morphologies of the Alloy 617 samples exhibited distinct evidence of intergranular corrosion. Compact chromium oxide layers were observed on the sample surfaces. The oxidation mechanisms of this alloy in the designated environments are discussed.

  3. Phase Stability Diagrams for High Temperature Corrosion Processes

    Directory of Open Access Journals (Sweden)

    J. J. Ramos-Hernandez

    2013-01-01

    Full Text Available Corrosion phenomena of metals by fused salts depend on chemical composition of the melt and environmental conditions of the system. Detail knowledge of chemistry and thermodynamic of aggressive species formed during the corrosion process is essential for a better understanding of materials degradation exposed to high temperature. When there is a lack of kinetic data for the corrosion processes, an alternative to understand the thermodynamic behavior of chemical species is to utilize phase stability diagrams. Nowadays, there are several specialized software programs to calculate phase stability diagrams. These programs are based on thermodynamics of chemical reactions. Using a thermodynamic data base allows the calculation of different types of phase diagrams. However, sometimes it is difficult to have access to such data bases. In this work, an alternative way to calculate phase stability diagrams is presented. The work is exemplified in the Na-V-S-O and Al-Na-V-S-O systems. This system was chosen because vanadium salts is one of the more aggressive system for all engineering alloys, especially in those processes where fossil fuels are used.

  4. High temperature corrosion under conditions simulating biomass firing: depth-resolved phase identification

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2014-01-01

    Both cross-sectional and plan view, ‘top-down’ characterization methods were employed , for a depth-resolved characterization of corrosion products resulting from high temperature corrosion under laboratory conditions simulating biomass firing. Samples of an austenitic stainless steel (TP 347H FG...... of the corrosion product. Results from this comprehensive characterization revealed more details on the morphology and composition of the corrosion product....

  5. 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.

  6. Study of the high-temperature corrosion of heat-resisting alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wada, K.

    1986-01-01

    An experimental study is reported of the corrosion resistance of the heat-resistant materials which play such an important role in the development of high-efficiency coal gasification combined-cycle power generation. Specifically, a study was made of the high-temperature and molten salt corrosion of nickel base alloys in coal combustion gas environments. The authors outline various types of high-temperature corrosion which occur: oxidation, sulfidation, decarburization and carburizing, nitridation, hot corrosion and halogenation. The mechanisms involved in molten salt corrosion are explained with reference to various models and currently available data. Finally, a study of electro-chemical measuring methods is reported. The authors conclude that future work on corrosion in coal gasification combined cycle power generation systems should concentrate on the following items: 1) elucidating the conditions under which molten salts form; 2) developing methods for predicting the quantity of molten salts which will form, and for assessing their contribution to corrosion; 3) evaluating the corrosion resistance of specific alloys to molten salts of given composition; 4) clarifying the effect of alloy surface temperature on corrosion resistance and local corrosion; and 5) developing techniques for predicting the amount of corrosion. 24 references, 28 figures, 7 tables.

  7. High-temperature metal corrosion tests for HI decomposer

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jin Young; Kim, Young Soo; Sah, In Jin; No, Hee Cheon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2012-05-15

    The Sulfur-Iodine thermochemical Nuclear hydrogen production process is composed of three parts, Bunsen reaction, sulfuric acid decomposition reaction and hydriodic acid decomposition reaction. Among them, hydriodic acid decomposition reaction has low kinetics and equilibrium yield is poor, being an efficiency-determining step.1) Thus, many efforts are tried to raise the reaction rate and yield, such as extractive/reactive distillation or EED method. High temperature decomposition process,2) another candidate of HI decomposition method nowadays, has a simple process but due to highly corrosive environment, a material problem is one of crucial obstacles. In this paper, a number of structure material candidates are tested at high temperature for HI decomposition process

  8. 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.

  9. High Temperature Corrosion under Laboratory Conditions Simulating Biomass-Firing: A Comprehensive Characterization of Corrosion Products

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2014-01-01

    characterization of the corrosion products. The corrosion products consisted of three layers: i) the outermost layer consisting of a mixed layer of K2SO4 and FexOy on a partly molten layer of the initial deposit, ii) the middle layer consists of spinel (FeCr2O4) and Fe2O3, and iii) the innermost layer is a sponge......-like Ni3S2 containing layer. At the corrosion front, Cl-rich protrusions were observed. Results indicate that selective corrosion of Fe and Cr by Cl, active oxidation and sulphidation attack of Ni are possible corrosion mechanisms....

  10. High temperature corrosion issues in energy-related systems

    Directory of Open Access Journals (Sweden)

    Stringer John

    2004-01-01

    Full Text Available The large majority of electric power that is generated world-wide involves heat engines of one kind or another. The significant exceptions are hydroelectric generation; wind; and photovoltaics. The thermal sources for the heat engines include: fossil fuels, nuclear fission, biomass, geothermal sources, and solar radiation. There has been a progressive move to higher overall cycle efficiencies for at least one hundred years, and in the case of fossil fuels this has accelerated recently in part because of concerns about greenhouse gas emissions, notably CO2. For a heat engine, the overall efficiency is closely related to the difference between the highest temperature in the cycle and the lowest temperature. In most cases, this has resulted in an increase in the high temperature, and this in turn has led to increasing demands on the materials of construction used in the high temperature end of the systems. One of the issues is the chemical degradation because of reactions between the materials of construction and the environments to which they are exposed: this is high temperature corrosion. This paper will describe the issues for a range of current heat engines.

  11. 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.

  12. Corrosion inhibition in drinking water. Effect of temperature. Part 2. Copper. Inhibicion de la corrosion en agua potable. Efecto de la temperature. Parte II Cobre

    Energy Technology Data Exchange (ETDEWEB)

    Royuela, J.J.; Otero, E. (CENIM.CSIC. (Spain))

    1994-01-01

    The corrosivity of several drinking waters, with and without addition of sodium silicate and sodium polyphosphate as inhibitor, in contact with copper, is studied in the range, is the range 20-65 degree centigree. The corrosion rate in the course of time was followed by means of the polarization resistance method. Linearity between potential and intensity of current is observed in the range- 30 to + 40 mV in relation with corrosion potential, E[sub 0]. Polarization curves were also drawn with the aim to obtain the Tafel slopes. E[sub 0] values are more active when inhibitor is present. With temperature increases corrosion rate. Inhibitor addition to the drinking water tested means a reduction of copper corrosion of about 50%. (Author) 31 refs.

  13. Deposition and High-Temperature Corrosion in Biomass-Fired Boilers

    DEFF Research Database (Denmark)

    Michelsen, Hanne Philbert

    This thesis describes the fate of potassium, chlorine, and sulfur in regard to deposition and corrosion problems in straw-fired boilers. Full-scale deposition studies at Rudkøbing CHP, Kyndby Power Station and Masnedø CHP revealed that straw may form massive deposits in the convective pass...... has only been detected in insignificant amounts in mature deposits in straw-fired boilers formed over months of operation.The corrosion of superheater tubes is closely connected to the material which are deposited on the surface and deposits containing potassium chloride can cause severe high......-temperature corrosion at elevated metal temperatures. Lab-scale corrosion experiments, where metal test elements were covered with synthetic potassium salts and real deposits and exposed to a simulated flue gas containing HCl(g) and SO2(g), provided information about the corrosion rate and corrosion mechanisms...

  14. Standard guide for corrosion tests in high temperature or high pressure environment, or both

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This guide covers procedures, specimens, and equipment for conducting laboratory corrosion tests on metallic materials under conditions of high pressure (HP) or the combination of high temperature and high pressure (HTHP). See for definitions of high pressure and temperature. 1.2 Tests conducted under HP or HTHP by their nature have special requirements. This guide establishes the basic considerations that are necessary when these conditions must be incorporated into laboratory corrosion tests. 1.3 The procedures and methods in this guide are applicable for conducting mass loss corrosion, localized corrosion, and electrochemical tests as well as for use in environmentally induced cracking tests that need to be conducted under HP or HTHP conditions. 1.4 The primary purpose for this guide is to promote consistency of corrosion test results. Furthermore, this guide will aid in the comparison of corrosion data between laboratories or testing organizations that utilize different equipment. 1.5 The values s...

  15. Evaluation of Iron Nickel Oxide Nanopowder as Corrosion Inhibitor: Effect of Metallic Cations on Carbon Steel in Aqueous NaCl

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhry, A. U.; Mishra, Brajendra [Colorado School of Mines, Denver (United States); Mittal, Vikas [The Petroleum Institute, Abu Dhabi (United Arab Emirates)

    2016-01-15

    The aim of this study was to evaluate the use of iron-nickel oxide (Fe{sub 2}O{sub 3}.NiO) nanopowder (FeNi) as an anti-corrosion pigment for a different application. The corrosion protection ability and the mechanism involved was determined using aqueous solution of FeNi prepared in a corrosive solution containing 3.5 wt.% NaCl. Anti-corrosion abilities of aqueous solution were determined using electrochemical impedance spectroscopy (EIS) on line pipe steel (API 5L X-80). The protection mechanism involved the adsorption of metallic cations on the steel surface forming a protective film. Analysis of EIS spectra revealed that corrosion inhibition occurred at low concentration, whereas higher concentration of aqueous solution produced induction behavior.

  16. Laboratory Investigation of High Temperature Corrosion in Straw fired Power Plants

    DEFF Research Database (Denmark)

    Montgomery, Melanie

    1998-01-01

    Corrosion in straw-fired power plants has been studied in the laboratory for Sandvik 8LR30 and Sanicro 28. The influence of HCl and SO2 was investigated at 600C metal temperature for upto 300 hours.In addition the corrosion behaviour of the same materials was examined in ash taken from a straw......-fired boiler. The corrosive potential of the individual components were thus evaluated...

  17. The effects of cold rolling temperature on corrosion resistance of pure iron

    Science.gov (United States)

    Jinlong, Lv; Hongyun, Luo

    2014-10-01

    The effects of cold rolling temperature on grain size and grain orientation of pure iron were investigated. Comparing with sample rolled at room temperature, the grain refinement was facilitated in sample obtained by cryogenic cold rolling at liquid-nitrogen temperature. However, the grain orientation changed little for two samples. It was shown that cathodic hydrogen evolution reaction could govern the corrosion reaction for pure iron in sulfuric acid solution. The grain refinement obtained by rolling improved the corrosion resistance of iron in sulfuric acid solution, borate buffer solution and borate buffer solution with chloride ion. However, comparing with iron rolled at room temperature, the corrosion resistance of iron obtained by cryogenic temperature rolling was lower. Comparing with iron rolled at room temperature, higher dislocation density in iron rolled at cryogenic temperature reduced its corrosion resistance.

  18. The effect of alloy composition on the mechanism of stress-corrosion cracking of titanium alloys in aqueous environments

    Science.gov (United States)

    Wood, R. A.; Boyd, J. D.; Williams, D. N.; Jaffee, R. I.

    1972-01-01

    A detailed study was made of the relation between the size distribution of Ti3Al particles in a Ti-8Al alloy and the tensile properties measured in air and in saltwater. The size distribution of Ti3Al was varied by isothermal aging for various times at temperatures in the range 770 to 970 K (930 to 1290 F). The aging kinetics were found to be relatively slow. Quantitative measurements of the particle coarsening rate at 920 K (1200 F) showed good agreement with the predicted behavior for coarsening controlled by matrix diffusion, and suggested that the specific free energy of the Ti3Al alpha interface in negligible small. In all cases, the Ti3Al particles were sheared by the glide dislocations. It was concluded that there is a definite correlation between the presence of deformable Ti3Al particles and an alloy's susceptibility to aqueous stress corrosion cracking. Furthermore, the appearance of the surface slip lines and the dislocation substructure in deformed specimens suggest that the specific effect of the Ti3Al particles is to cause a nonhomogeneous planar slip character and an enhanced chemical potential of the slip bands.

  19. High temperature corrosion investigation in an oxyfuel combustion test rig

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Bjurman, M.; Hjörnhede, A

    2014-01-01

    Oxyfuel firing and subsequent capture of CO2 is a way to reduce CO2 emissions from coal‐fired boilers. Literature is summarized highlighting results which may contribute to understanding of the corrosion processes in an oxyfuel boiler.Tests were conducted in a 500 kWth oxyfuel test facility...... constructed by Brandenburg Technical University to gain understanding into oxyfuel firing. Two air‐cooled corrosion probes were exposed in this oxyfuel combustion chamber where the fuel was lignite. Gas composition was measured at the location of testing. Various alloys from a 2½ Cr steel, austenitic steels...... (perhaps carburized) zone was used as a measure of corrosion rates. The lowest alloyed steel had the highest corrosion rate, and the other austenitic and nickel alloys had much lower corrosion rates. Precipitates in the alloy adjacent the corrosion front were revealed for both Sanicro 28 and C‐276. However...

  20. Influence of incubation temperature on biofilm formation and corrosion of carbon steel by Serratia marcescens

    Science.gov (United States)

    Harimawan, Ardiyan; Devianto, Hary; Kurniawan, Ignatius Chandra; Utomo, Josephine Christine

    2017-01-01

    Microbial induced corrosion (MIC) or biocorrosion is one type of corrosion, directly or indirectly influenced by microbial activities, by forming biofilm and adhering on the metal surface. When forming biofilm, the microorganisms can produce extracellular products which influence the cathodic and anodic reactions on metal surfaces. This will result in electrochemical changes in the interface between the biofilm and the metal surface, leading to corrosion and deterioration of the metal. MIC might be caused by various types of microorganism which leads to different corrosion mechanism and reaction kinetics. Furthermore, this process will also be influenced by various environmental conditions, such as pH and temperature. This research is aimed to determine the effect of incubation temperature on corrosion of carbon steel caused by Serratia marcescens in a mixture solution of synthetic seawater with Luria Bertani medium with a ratio of 4:1. The incubation was performed for 19 days with incubation temperature of 30, 37, and 50°C. The analyses of biofilm were conducted by total plate count (TPC), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Biofilm was found to be evenly growth on the surface and increasing with increasing incubation temperature. It consists of functional group of alcohol, alkane, amine, nitro, sulfate, carboxylic acid, and polysulfide. The analyses of the corrosion were conducted by gravimetric and X-ray diffraction (XRD). Higher incubation temperature was found to increase the corrosion rate. However, the corrosion products were not detected by XRD analysis.

  1. Corrosion of metallic materials by uranium hexafluoride at high temperatures (1963); Corrosion de materiaux metalliques par l'hexafluorure d'uranium a haute temperature (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Langlois, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    The corrosion of the following metals or alloys by UF{sub 6}: nickel, monel, Inconel, gold, platinum, stainless steel, is studied in the temperature range from 300 to 1000 deg. C. The test method, designed to avoid heating the apparatus containing the corrosive fluid to a high temperature, consists in using threadlike samples heated by the Joule effect, the rest of the apparatus being maintained close to room temperature. This technique makes it possible also to determine continuously the penetration of the corrosion by measuring the electrical resistance of the sample with a double Thomson bridge. A series of rapid comparison tests shows that stainless steel, precious metals and Inconel are attacked far too rapidly to be used above 500 deg. C; only monel and especially nickel appear capable of resisting at high temperatures. The detailed examination of the behaviour of nickel shows that the metallic fluoride is volatilized and that this influences the corrosion rate. It shows also the existence of a temperature zone situated between 550 and 700 deg. C in which occurs A strong intergranular corrosion the cause of which appears to be the presence of impurities in the metal. (author) [French] La corrosion par l'UF{sub 6} des metaux ou alliages suivants: lickel, monel, inconel, or, platine, acier inoxydable, est etudiee dans le un domaine de temperature compris entre 300 et 1000 deg. C. La methode d'essai, destinee a eviter le chauffage de l'enceinte contenant le fluide corrosif a temperature elevee, consiste a utiliser des eprouvettes filiformes, echauffees par effet Joule, le reste de l'appareillage etant maintenu a une temperature proche de l'ambiance. Cette technique permet en outre de determiner en continu la penetration de la corrosion, par mesure de la resistance electrique de l'eprouvette, au moyen d'un pont double de Thomson. Une serie d'essais comparatifs, assez sommaires, montre que l'acier inoxydable, les metaux

  2. Transitions in aqueous solutions of sucrose at subzero temperatures

    Czech Academy of Sciences Publication Activity Database

    Sikora, Antonín; Dupanov, V. O.; Kratochvíl, Jaroslav; Zámečník, J.

    2007-01-01

    Roč. 46, č. 1 (2007), s. 71-85 ISSN 0022-2348 R&D Projects: GA ČR(CZ) GA522/04/0384 Institutional research plan: CEZ:AV0Z40500505 Keywords : aqueous sucrose solutions * subzero temperature * glass transitions Subject RIV: BJ - Thermodynamics Impact factor: 0.809, year: 2007

  3. SUSCEPTIBILITY OF ALLOY 690 TO STRESS CORROSION CRACKING IN CAUSTIC AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    DONG-JIN KIM

    2013-02-01

    Full Text Available Stress corrosion cracking (SCC behaviors of Alloy 690 were studied in lead-containing aqueous alkaline solutions using the slow strain rate tension (SSRT tests in 0.1M and 2.5M NaOH with and without PbO at 315°C. The side and fracture surfaces of the alloy were then examined using scanning electron microscopy after the SSRT test. Microstructure and composition of the surface oxide layer were analyzed by using a field emission transmission electron microscopy, equipped with an energy dispersive X-ray spectroscopy. Even though Alloy 690 was almost immune to SCC in 0.1M NaOH solution, irrespective of PbO addition, the SCC resistance of Alloy 690 decreased in a 2.5M NaOH solution and further decreased by the addition of PbO. Based on thermodynamic stability and solubility of oxide, high Cr of 30wt% in the Alloy 690 is favorable to SCC in mild alkaline and acidic solutions whereas the SCC resistance of high Cr Alloy 690 is weakened drastically in the strong alkaline solution where the oxide is not stable any longer and solubility is too high to form a passive oxide locally.

  4. Passivation and corrosion of the high performance materials alloy 33, alloy 31 and nickel in LiBr solution at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-07-01

    Aqueous solutions containing high concentrations of Lithium Bromide are employed as absorbent solutions for almost all types of heating and refrigerating absorption systems that use natural gas or steam as energy sources. LiBr solutions can cause serious corrosion problems in common metallic components. The objective of the present work was to study the corrosion resistance of new high alloyed materials in commercial LiBr heavy brine solution (which contains chromate as inhibitor), at different temperatures (25, 30, 40, 50, 60, 70 and 80 deg. C). The materials tested were stainless steels Alloy 33 (UNS R20033), a new corrosion resistant austenitic material alloyed with nominally (wt%) 33 Cr, 32 Fe, 31 Ni; Nicrofer 3127 hMo-alloy 31 (UNS N08031), an iron-nickel-chromium-molybdenum alloy with nitrogen; and pure Nickel. Corrosion resistance was estimated from the cyclic potentiodynamic polarization curves, comparing OCP values, calculating corrosion potentials and current rates from Tafel analysis; in order to characterize the passivating behaviour of the alloys the study was completed with the analysis of the pitting potentials, passivating current and re-passivating properties at the temperatures under study. Passivating properties are well observed in all the samples in commercial LiBr solution at all temperatures. In these cases, passivation properties decrease with temperature. (authors)

  5. Temperature factors effect on occurrence of stress corrosion cracking of main gas pipeline

    Science.gov (United States)

    Nazarova, M. N.; Akhmetov, R. R.; Krainov, S. A.

    2017-10-01

    The purpose of the article is to analyze and compare the data in order to contribute to the formation of an objective opinion on the issue of the growth of stress corrosion defects of the main gas pipeline. According to available data, a histogram of the dependence of defects due to stress corrosion on the distance from the compressor station was constructed, and graphs of the dependence of the accident density due to stress corrosion in the winter and summer were also plotted. Data on activation energy were collected and analyzed in which occurrence of stress corrosion is most likely constructed, a plot of activation energy versus temperature is plotted, and the process of occurrence of stress corrosion by the example of two different grades of steels under the action of different temperatures was analyzed.

  6. Influence of yttria surface modification on high temperature corrosion of porous Ni22Cr alloy

    DEFF Research Database (Denmark)

    Karczewski, Jakub; Dunst, Katarzyna; Jasinski, Piotr

    2017-01-01

    Protective coatings for porous alloys for high temperature use are relatively new materials. Their main drawback is high temperature corrosion. In this work protective coatings based the on Y-precursor infiltrated into the sintered Ni22Cr alloys are studied at 700°C. Effects of the amount...... of the protective phase on the resulting corrosion properties are evaluated in air and humidified hydrogen. Weight gain of the samples, their open porosities and microstructures are analyzed and compared. Results show, that by the addition of even a minor amount of the Y-precursor corrosion rates can be decreased...

  7. Electrodeposition of r-GO/SiC nano-composites on Magnesium and its Corrosion Behavior in Aqueous Electrolyte

    Science.gov (United States)

    Kavimani, V.; K, Soorya Prakash; R, Rajesh; Rammasamy, Devaraj; Selvaraj, Nivas Babu; Yang, Tao; Prabakaran, Balasubramanian; Jothi, Sathiskumar

    2017-12-01

    In this paper a detailed investigation for corrosion behavior of magnesium substrate electrodeposited differently by nanoparticles like Reduced Graphene Oxide (r-GO synthesized through Modified Hummer's Method), Silicon Carbide (SiCsbnd mechanically alloyed) and also r-GO/SiC nanocomposites (dispersed through ultrasonication process) as coating materials for varying time period was done. Synthesized nanocomposite was characterized through various physio-chemical techniques and confirmation of the same was carried out. Surface morphology of the developed set of specimens was scrutinized through SEM and EDAX which establishes a clean surface coating with minimal defects attainment through electro deposition technique. Electrochemical corrosion behavior for the magnesium substrates coated with r-GO, SiC, r-GO/SiC for 5 and 10 min coating time period was conceded over in 0.1 M of NaCl and Na2SO4 aqueous solution using Tafel polarization and then compared with a pure magnesium substrate. r-GO/SiC nanocomposite coated magnesium substrate showcased a drastic breakthrough in corrosion resistance when compared with other set of specimens in aqueous medium. Delamination behavior for the same set of specimens was carried and the r-GO/SiC nanocomposite coated magnesium exposed a minimum delamination area accounting to the hydrophobic property of graphene and the binding effect of SiC nano particles.

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

    Science.gov (United States)

    Wall, Douglas; Stoner, Glenn E.

    1991-01-01

    Summary information is included for electrochemical aspects of stress corrosion cracking in alloy 2090 and an introduction to the work to be initiated on the new X2095 (Weldalite) alloy system. Stress corrosion cracking (SCC) was studied in both S-T and L-T orientations in alloy 2090. A constant load TTF test was performed in several environments with a potentiostatically applied potential. In the same environments the electrochemical behavior of phases found along subgrain boundaries was assessed. It was found that rapid failure due to SCC occurred when the following criteria was met: E(sub BR,T1) is less than E(sub applied) is less than E(sub Br, matrix phase). Although the L-T orientation is usually considered more resistant to SCC, failures in this orientation occurred when the stated criteria was met. This may be due to the relatively isotropic geometry of the subgrains which measure approximately 12 to 25 microns in diameters. Initial studies of alloy X2095 includes electrochemical characterization of three compositional variations each at three temperatures. The role of T(sub 1) dissolution in SCC behavior is addressed using techniques similar to those used in the research of 2090 described. SCC susceptibility is also studied using alternate immersion facilities at Reynolds Metals Corporation. Pitting is investigated in terms of stability, role of precipitate phases and constituent particles, and as initiation sites for SCC. In all research endeavors, attempts are made to link electrochemistry to microstructure. Previous work on 2090 provides a convenient basis for comparison since both alloys contain T(sub 1) precipitates but with different distributions. In 2090 T(sub 1) forms preferentially on subgrain boundaries whereas in X2095 the microstructure appears to be more homogeneous with finer T(sub 1) particles. Another point for comparison is the delta prime strengthening phase found in 2090 but absent in X2095.

  9. Aqueous Geochemistry at High Pressures and High Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Bass, Jay D. [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2015-05-21

    This project is aimed at experimental characterization of the sound velocities, equations of state (EOS), and derived physical and chemical properties of aqueous solutions and carbon dioxide at extreme pressure and temperature conditions relevant to processes occurring in the interior of the Earth. Chemical transport, phase changes (including melting), fluid-solid reactions, and formation of magmatic liquids at convergent plat boundaries are a key motivation for this project. Research in this area has long been limited by the extreme experimental challenges and lack of data under the appropriate pressure-temperature (P-T) conditions. The vast majority of studies of aqueous geochemistry relevant to terrestrial problems of fluid-rock interactions have been conducted at 0.3 GPa or less, and the widely used Helgeson-Kirkham-Flowers equation of state for aqueous species is applicable only at ~ < 0.5 GPa. These limits are unfortunate because fluid flow and reactions plays a central role in many deeper environments. Recent efforts including our own, have resulted in new experimental techniques that now make it possible to investigate properties of homogeneous and heterogeneous equilibria involving aqueous species and minerals over a much broader range of pressure and temperature appropriate for deep crustal and upper mantle processes involving water-rich fluids. We carried out 1) Brillouin scattering measurements of the equations of state and molar volume of water and carbon dioxide to over 10 GPa and 870K using precise resistance heating of samples under pressure in the diamond anvil cell, and 2) the phase diagrams of the water and CO2, and 3) Exploring new experimental approaches, including CO2 laser heating of samples in a diamond cell, to measurements of sound velocities, EOS, and phase relations by Brillouin scattering to far greater pressures and temperatures.

  10. Corrosion-resistant coating for GTE compressor parts made of steels with low tempering temperatures

    Science.gov (United States)

    Muboyadzhyan, S. A.; Egorova, L. P.; Gorlov, D. S.; Bulavintseva, E. E.

    2017-01-01

    The corrosion resistance of an Ni-Co-Cr-Al-Si-Y + SPh (SPh is silicophosphate impregnation) alloy coating on 30Kh13, 38Kh2MYuA, VKS5, and VKS7 structural steels with low tempering temperatures has been studied. The steel-coating compositions have been tested to determine the accelerated cyclic corrosion resistance, the corrosion resistance under tropic climate chamber conditions and in salt fog, the stress corrosion resistance, and the corrosion resistance in an industrial atmosphere. The heat stability of coated samples is studied, metallographic studies of the samples before and after the tests are performed, and the influence of the coating on the strength characteristics of the structural steels is studied.

  11. Inhibiting properties and adsorption of an amine based fatty acid corrosion inhibitor on carbon steel in aqueous carbon dioxide solutions

    Energy Technology Data Exchange (ETDEWEB)

    Buchweishaija, Joseph

    1997-12-31

    Carbon dioxide corrosion is a major corrosion problem in oil and gas production systems and many organic inhibitors have been tested and used to protect the substrate from corrosion. This thesis studies the mechanism of interaction of the inhibitor molecule with the metallic substrate and how this affects the dissolution rate of the metal. The performance of a commercial amine based fatty acid corrosion inhibitor has been investigated using rotating cylinder electrodes and carbon steel electrodes in CO{sub 2} saturated formation water in the temperature range between 35 to 80{sup o}C. The corrosion process was monitored by electrochemical impedance measurements, and at the end of each experiment full polarization curves were recorded. When the inhibitor was applied on noncorroded electrodes, high inhibitor performance, over 99.7%, was observed independent of temperature. On precorroded electrodes inhibitor performance was found to depend on temperature and time of precorrosion. Above 60{sup o}C, the inhibitor performance decreased with increasing time of precorrosion, presumably because of the formation of a corrosion film of either iron carbonate or a combination of iron carbonate and iron carbide which prevent the inhibitor from reaching the surface. The inhibitor protection efficiency was assumed to be associated with the degree of inhibitor coverage at the material surface, and adsorption isotherms have been calculated in the concentration range between 0.1 ppm and 100 ppm. A Langmuir isotherm was found to give the best fit. The inhibitor performance on a 2 days precorroded rotating electrode was investigated at different solution pH ranging between 4.5 and 6.5 at 35{sup o}C. 130 refs., 80 figs., 22 tabs.

  12. Experimental investigation on the short-term impact of temperature and moisture on reinforcement corrosion

    DEFF Research Database (Denmark)

    Michel, A.; Nygaard, P.V.; Geiker, M.R.

    2013-01-01

    In this study, reinforced concrete specimens with and without mixed-in chlorides were conditioned at different relative humidities and subsequently subjected to varying temperatures. Results of the study confirmed that neither temperature nor moisture content have a major impact on the corrosion...... state and rate of passively corroding reinforcement. For actively corroding reinforcement, a temperature and moisture dependent corrosion rate was observed. The temperature dependency could be described by the Arrhenius equation with moisture dependent activation energies of approximately 10kJ/mol at 75...

  13. Peculiar high temperature corrosion of martensite alloy under impact of Estonian oil shale fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Tallermo, H.; Klevtsov, I. [Thermal Engineering Department of Tallinn Technical University, Tallinn (Estonia)

    1998-12-31

    The superheaters` surfaces of oil shale steam boiler made of pearlitic and austenitic alloys, are subject to intensive corrosion, mainly due to presence of chlorine in external deposits. The applicability of martensitic alloys X1OCrMoVNb91 and X20CrMoV121 for superheaters is examined here and empirical equations allowing to predict alloys` corrosion resistance in the range of operational temperatures are established. Alloy X1OCrMoVNb91 is found been most perspective for superheaters of boilers firing fossil fuel that contain alkaline metals and chlorine. The abnormal dependence of corrosion resistance of martensitic alloys on temperature is revealed, namely, corrosion at 580 deg C in presence of oil shale fly ash is more intensive than at 620 deg C. (orig.) 2 refs.

  14. A Corrosion Investigation of Solder Candidates for High-Temperature Applications

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Ambat, Rajan

    2009-01-01

    , corrosion investigation was carried out on potential ternary lead-free candidate alloys based on these binary alloys for high temperature applications. These promising ternary candidate alloys were determined by the CALPHAD approach based on the solidification criterion and the nature of the phases...... predicted in the bulk solder. This work reveals that the Au-Sn based candidate alloys close to the eutectic composition (20 wt. % Sn) are more corrosion resistant than the Au-Ge based ones....

  15. High temperature, low expansion, corrosion resistant ceramic and gas turbine

    Science.gov (United States)

    Rauch, Sr., Harry W.

    1981-01-01

    The present invention relates to ZrO.sub.2 -MgO-Al.sub.2 O.sub.3 -SiO.sub.2 ceramic materials having improved thermal stability and corrosion resistant properties. The utilization of these ceramic materials as heat exchangers for gas turbine engines is also disclosed.

  16. Corrosion behavior of Mg–Gd–Zn based alloys in aqueous NaCl solution

    Directory of Open Access Journals (Sweden)

    A. Srinivasan

    2014-09-01

    Full Text Available The corrosion behavior of Mg-10Gd–xZn (x = 2, 6 wt.% alloys in 0.5 wt.% NaCl solution was investigated. Microstructures of both the alloys consisted of (Mg,Zn3Gd phase and lamellar long period stacking ordered (LPSO phase. The morphology of the second phase at the grain boundary differed in both alloys: it was a continuous network structure in Mg–10Gd–6Zn, whereas it was relatively discrete in Mg–10Gd–2Zn. The dendrites were finer in size and highly branched in Mg–10Gd–6Zn. The corrosion results indicated that the increase in Zn content increased the corrosion rate in Mg–10Gd–xZn alloys. Micro-galvanic corrosion occurred near the grain boundary in both alloys initially as the grain boundary phase was stable and acted as a cathode, however, filiform corrosion dominated in the later stage, which was facilitated by the LPSO phase in the matrix. Severe micro-galvanic corrosion occurred in Mg–10Gd–6Zn due to the higher volume of second phase. The stability of the second phase at the grain boundary was altered and dissolved after the long immersion times. Probably the NaCl solution chemically reacted with the grain boundary phase and de-stabilized it during the long immersion times, and was removed by the chromic acid used for the corrosion product removal.

  17. Effect of temperature on the application of Myrmecodia Pendans extract for environmentally friendly corrosion inhibitor

    Science.gov (United States)

    Pradityana, Atria; Sulistijono, Winarto, Widiyono, Eddy; Luwar, Budi; Mursid, Mahirul

    2017-05-01

    One of the efforts to control the corrosion rate used is to add inhibitors. Corrosion is a a decrease in the quality of a material (metal) caused by a chemical reaction between the metal and its environment. The purpose of this study is to analyze the effect of temperature on the corrosive medium in the presence of plant, Myrmecodia Pendans extracts as an organic inhibitor. This study used a type of carbon steel APT 5L Grade B with temperature 30°C, 40°C, 50°C. Corrosive medium used was 1M HCl with varying concentrations of plant extracts Myrmecodia Pendans 100 to 500 mg I L. Maceration method is a method used for extracting plants, Myrmecodia Pendans. The effectiveness of the use of organic inhibitors Myrmecodia Pendans in acid known by some measurements. There are ETS and FTTR. From the results of of measurements carried out, the Myrmecodia Pendans extract able to reduce corrosion rate. The resulting best inhibition efficiency of 82,88% at 30°C temperature conditions and extract the addition of 500 mg I L. Protection system that occurs is an Myrmecodia Pendans extract form a passive film on the surface of the material so as to reduce the corrosive attack.

  18. Corrosion behavior of HA-316L SS biocomposites in aqueous solutions

    OpenAIRE

    Robin, Alain; Silva,Gilbert; Rosa, Jorge Luiz

    2013-01-01

    316L stainless steel and Hydroxyapatite (5, 20 and 50 wt. (%) HA)-316L stainless steel composites were fabricated by mechanical alloying technique, pressing and sintering from 316L and HA powders. The corrosion behavior of both sintered 316L and HA-316L composites was evaluated by electrochemical techniques in simulated body fluid (Ringer's solution) and in 0.1M HCl solution which simulates occluded cell corrosion conditions. The results indicate that 316L stainless steel and HA-316L composit...

  19. 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.

  20. The effect of tempering temperature on pitting corrosion resistance of 420 stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Anwar, Moch Syaiful, E-mail: moch026@lipi.go.id; Prifiharni, Siska, E-mail: sisk002@lipi.go.id; Mabruri, Efendi, E-mail: effe004@lipi.go.id [Research Center for Metallurgy and Materials – Indonesian Institute of Sciences (LIPI) Kawasan PUSPIPTEK Building 470 – South of Tangerang – Banten – 15314 (Indonesia)

    2016-04-19

    The AISI Type 420 stainless steels are commonly used to steam generators, mixer blades, etc. These stainless steels are most prone to pitting in dissolved Cl{sup −} containing environments. In this paper, the effect of tempering temperature on pitting corrosion resistance of AISI Type 420 stainless steels was studied. The AISI Type 420 stainless steels specimens were heat treated at the temperature of 1050°C for 1 hour to reach austenite stabilization and then quench in the oil. After that, the specimens were tempered at the temperature of 150, 250, 350 and 450°C for 30 minutes and then air cooled to the room temperature. The electrochemical potentiodynamic polarization test was conducted at 3.5% sodium chloride solution to evaluate corrosion rate and pitting corrosion behaviour. The Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) were used to evaluate the pitting corrosion product. The result have shown that highest pitting potential was found in the sample tempered at 250°C and corrosion pits were found to initiate preferentially around chromium carbides.

  1. The effect of tempering temperature on pitting corrosion resistance of 420 stainless steels

    Science.gov (United States)

    Anwar, Moch. Syaiful; Prifiharni, Siska; Mabruri, Efendi

    2016-04-01

    The AISI Type 420 stainless steels are commonly used to steam generators, mixer blades, etc. These stainless steels are most prone to pitting in dissolved Cl- containing environments. In this paper, the effect of tempering temperature on pitting corrosion resistance of AISI Type 420 stainless steels was studied. The AISI Type 420 stainless steels specimens were heat treated at the temperature of 1050°C for 1 hour to reach austenite stabilization and then quench in the oil. After that, the specimens were tempered at the temperature of 150, 250, 350 and 450°C for 30 minutes and then air cooled to the room temperature. The electrochemical potentiodynamic polarization test was conducted at 3.5% sodium chloride solution to evaluate corrosion rate and pitting corrosion behaviour. The Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) were used to evaluate the pitting corrosion product. The result have shown that highest pitting potential was found in the sample tempered at 250°C and corrosion pits were found to initiate preferentially around chromium carbides.

  2. High temperature corrosion of superheater materials for power production through biomass

    Energy Technology Data Exchange (ETDEWEB)

    Gotthjaelp, K.; Broendsted, P. [Forskningscenter Risoe (Denmark); Jansen, P. [FORCE Institute (Denmark); Montgomery, M.; Nielsen, K.; Maahn, E. [Technical Univ. of Denmark, Corrosion and Surface Techn. Inst. of Manufacturing Engineering (Denmark)

    1996-08-01

    The aim of the present study has been to establish a fundamental knowledge of the corrosion mechanisms acting on materials for use in biomass fired power plants. The knowledge is created based on laboratory exposures of selected materials in well-defined corrosive gas environments. The experiments using this facility includes corrosion studies of two types of high temperature resistant steels, Sanvik 8LR30 (18Cr 10Ni Ti) and Sanicro 28 (27Cr 31Ni 4Mo), investigated at 600 deg. C in time intervals up to 300 hours. The influence of HCl (200 ppm) and of SO{sub 2} (300 ppm) on the corrosion progress has been investigated. In addition the corrosion behaviour of the same materials was investigated after having been exposed under a cover of ash in air in a furnace at temperatures of 525 deg. C, 600 deg. C, and 700 deg. C. The ashes utilised are from a straw fired power plant and a synthetic ash composed of potassium chloride (KCl) and potassium sulphate (K{sub 2}SO{sub 4}). Different analysis techniques to characterise the composition of the ash coatings have been investigated in order to judge the reliability and accuracy of the SEM-EDX method. The results are considered as an important step towards a better understanding of the high temperature corrosion under the conditions found in biomass fired power plants. One of the problems to solve in a suggested subsequent project is to combine the effect of the aggressive gases (SO{sub 2} and HCl) and the active ash coatings on high temperature corrosion of materials. (EG) 20 refs.

  3. Polymer concrete composites for the production of high strength pipe and linings in high temperature corrosive environments

    Science.gov (United States)

    Zeldin, A.; Carciello, N.; Fontana, J.; Kukacka, L.

    High temperature corrosive resistant, non-aqueous polymer concrete composites are described. They comprise about 12 to 20% by weight of a water-insoluble polymer binder polymerized in situ from a liquid monomer mixture consisting essentially of about 40 to 70% by weight of styrene, about 25 to 45% by weight acrylonitrile and about 2.5 to 7.5% by weight acrylamide or methacrylamide and about 1 to 10% by weight of a crosslinking agent. This agent is selected from the group consisting of trimethylolpropane trimethacrylate and divinyl benzene; and about 80 to 88% by weight of an inert inorganic filler system containing silica sand and portland cement, and optionally Fe/sub 2/O/sub 3/ or carbon black or mica. A free radical initiator such as di-tert-butyl peroxide, azobisisobutyronitrile, benzoyl peroxide, lauryl peroxide, other organic peroxides and combinations thereof to initiate crosspolymerization of the monomer mixture in the presence of said inorganic filler.

  4. Radiolysis of Aqueous Benzene Solutions at higher temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, H.

    1964-07-15

    Aqueous solutions of benzene have been irradiated with Co {gamma}-rays with doses of up to 2.3 Mrad in the temperature region 100 - 200 C. At 100 C a linear relationship between the phenol concentration and the absorbed dose was obtained, but at 150 C and at higher temperatures the rate of the phenol formation increased significantly after an initial constant period. With higher doses the rate decreased again, falling almost to zero at 200 C after a dose of 2.2 Mrad. The G value of phenol in the initial linear period increased from 2.8 at 100 C to 8.0 at 200 C. The reaction mechanism is discussed and reactions constituting a chain reaction are suggested. The result of the addition of iron ions and of a few inorganic oxides to the system is presented and briefly discussed.

  5. Application of the aqueous coating suspension for the protection of Gas Turbine Engine parts from corrosion

    Directory of Open Access Journals (Sweden)

    E. G. Ivanov

    2015-01-01

    Full Text Available The article considers the physical nature of receiving diffusion coatings from aqueous suspensions of various alloys for various conditions and their further exploitation. Structure of coatings, advantages and features of the production of coatings from aqueous suspensions are shown. Based on the analysis of thermodynamic reactions in the systems of elements formulations of aqueous suspensions were developed and practical recommendations for their application to the parts of gas turbine engine were given.

  6. The stress corrosion resistance and the cryogenic temperature mechanical properties of annealed Nitronic 60 bar material

    Science.gov (United States)

    Montano, J. W. L.

    1977-01-01

    Ambient and cryogenic temperature mechanical properties and the ambient temperature stress corrosion properties of annealed, straightened, and centerless ground Nitronic 60 stainless steel alloy bar material are presented. The mechanical properties of longitudinal specimens were evaluated at test temperatures from ambient to liquid hydrogen. The tensile test data indicated increasing strength with decreasing temperature to -196 C. Below liquid nitrogen temperature the smooth tensile and notched tensile strengths decreased slightly while the elongation and reduction of area decreased drastically. The Charpy V-notched impact energy decreased steadily with decreasing test temperature. Stress corrosion tests were performed on longitudinal tensile specimens and transverse C-ring specimens exposed to: alternate immersion in a 3.5% NaCl bath; humidity cabinet; and a 5% salt spray atmosphere. The longitudinal tensile specimens experienced no corrosive attack. Approximately 3/4 of the transverse C-rings exposed to alternate immersion and to salt spray experienced a pitting attack on the top and bottom ends. Additional stress corrosion tests were performed on transverse tensile specimens. No failures occurred in the 90% stressed specimens exposed for 90 days in the alternate immersion and salt spray environments

  7. Corrosion inhibition in drinking water: Effect of temperature. Part I. Galvanized steel. Inhibicion de la corrosion en agua potable. Efecto de la temperatura. I parte. Acero galvanizado

    Energy Technology Data Exchange (ETDEWEB)

    Royuela, J.J.

    1994-01-01

    The corrosivity of several drinking waters, with and without addition of sodium silicate and sodium polyphosphate as inhibitor, in contact with galvanized steel, is studied in the range 20-65 degree centigree. The corrosion rate in the course of time was followed by means of the polarization resistance method. Linearity between potential and intensity of current is observed in the range-20 to + 30 mV from corrosion potential E[sub 0]. Polarization curves were also drawn with the aim to obtain the Tafel slopes. E[sub 0] values are more active when inhibitor is present. With temperature increases corrosion rate. Inhibitor addition to the waters tested means a reduction of galvanized steel corrosion of about 40%. (Author) 30 refs.

  8. Coal-fired power plants and the causes of high temperature corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Oakey, J.E.; Simms, N.J. [British Coal Corporation, Coal Technology Development Div., Cheltenham, Glos (United Kingdom); Tomkings, A.B. [ERA Technology Ltd., Leatherhead, Surrey (United Kingdom)

    1996-12-01

    The heat exchangers in all types of coal-fired power plant operate in aggressive, high temperature environments where high temperature corrosion can severely limit their service lives. The extent of this corrosion is governed by the combined effects of the operating conditions of the heat exchanger and the presence of corrosive species released from the coal during operation. This paper reviews the coal-related factors, such as ash deposition, which influence the operating environments of heat exchangers in three types of coal-fired power plant - conventional pulverized coal boilers, fluidized bed boilers and coal gasification systems. The effects on the performance of the materials used for these heat exchangers are then compared. (au) 35 refs.

  9. Material Solutions to Mitigate the Alkali Chloride-Induced High Temperature Corrosion

    DEFF Research Database (Denmark)

    Kiamehr, Saeed

    in the course of corrosion as well as the role of potassium chloride vapor. Results showed that while the majority of the alloys formed protective slow-growing oxides in the absence of KCl, they all suffered from significant attack when KCl was present. Thereby the inability of Cr to form a protective oxide......High temperature corrosion induced by potassium chloride (KCl) is a major challenge for biomass-based power plants. The current study aims at identification or development of alloys or coatings that can yield a better performance at a target metal temperature of 600oC compared to austenitic...... of metals. This was aimed at identifying the constituent elements of a corrosion resistant alloy. Calculations suggested Al, Si, Cr, Ti, Y, Ce, Ta, Hf and Zr as suitable oxide-forming elements as well as Mo, Ni and Co as suitable matrix-forming elements. However, the presence of potassium in the environment...

  10. Laboratory Study of High Temperature Corrosion in Straw-fired Power Plants

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Maahn, Ernst emanuel

    1997-01-01

    The components contributing to corrosion, HCl(g)SO2(g), KCl and K2SO4 were studied in the laboratory for Sandvik 8LR30 and Sanicro 28. The influence of HCl and SO2 was investigated at 600C material temperature and 600/800C flue gas temperature at time intervals up to 300 hours. The influence of ash...... deposits in air was examined at 525C-700C. Finally exposures were undertaken combining the aforementioned aggressive gas environment with the ash deposits. Thus the corrosion potential of individual components were evaluated and also whether they had a synergistic, antagonistic or additive effect on one...... another to influence the overall corrosion rate....

  11. Optimization of Oxidation Temperature for Commercially Pure Titanium to Achieve Improved Corrosion Resistance

    Science.gov (United States)

    Bansal, Rajesh; Singh, J. K.; Singh, Vakil; Singh, D. D. N.; Das, Parimal

    2017-03-01

    Thermal oxidation of commercially pure titanium (cp-Ti) was carried out at different temperatures, ranging from 200 to 900 °C to achieve optimum corrosion resistance of the thermally treated surface in simulated body fluid. Scanning electron microscopy, x-ray diffraction, Raman spectroscopy and electrochemical impedance spectroscopy techniques were used to characterize the oxides and assess their protective properties exposed in the test electrolyte. Maximum resistance toward corrosion was observed for samples oxidized at 500 °C. This was attributed to the formation of a composite layer of oxides at this temperature comprising Ti2O3 (titanium sesquioxide), anatase and rutile phases of TiO2 on the surface of cp-Ti. Formation of an intact and pore-free oxide-substrate interface also improved its corrosion resistance.

  12. The role of chelating agents on the corrosion mechanisms of aluminium in alkaline aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Mercier, D. [Centre d' Etudes de Chimie Metallurgique, CNRS, 15 rue Georges Urbain, 94407 Vitry Cedex (France); Barthes-Labrousse, M.-G. [Centre d' Etudes de Chimie Metallurgique, CNRS, 15 rue Georges Urbain, 94407 Vitry Cedex (France)], E-mail: marie-genevieve.barthes@u-psud.fr

    2009-02-15

    The influence of 1,2-diaminoethane (DAE) on the mechanism of aluminium corrosion in KOH solutions at pH 13 was investigated by combining time-resolved inductively coupled plasma optical emission spectrocopy, open-circuit potential measurements and X-ray photoelectron spectroscopy. In pure KOH solutions, a very slow corrosion rate is initially observed, corresponding to the dissolution of the native oxide layer. Following this incubation stage, the corrosion rate is increasing due to the formation and oxidation of Al hydride, until a steady state is reached. DAE behaves as a strong initial corrosion accelerator, due to synergistic effects with hydroxyl ions and a dissolution mechanism in three successive steps has been proposed: (i) a rapid initial dissolution induced by the formation and detachment from the surface of bidentate (chelate) Al-DAE metal bound surface complexes; (ii) a slower step ascribed to the formation and release of monodentate Al-DAE metal bound surface complexes and (iii) a final step dominated by direct oxidation of surface aluminium hydride by hydroxyl species as in pure KOH.

  13. ZM-21 magnesium alloy corrosion properties and cryogenic to elevated temperature mechanical properties

    Science.gov (United States)

    Montana, J. W.; Nelson, E. E.

    1972-01-01

    The mechanical properties of bare ZM-21 magnesium alloy flat tensile specimens were determined for test temperatures of +400 F, +300 F, +200 F, +80 F, 0 F, -100 F, -200 F, and -320 F. The ultimate tensile and yield strengths of the material increased with decreasing temperature with a corresponding reduction in elongation values. Stress corrosion tests performed under: (1) MSFC atmospheric conditions; (2) 95% relative humidity; and (3) submerged in 100 ppm chloride solution for 8 weeks indicated that the alloy is not susceptible to stress corrosion. The corrosion tests indicated that the material is susceptible to attack by crevice corrosion in high humidity and chemical type attack by chloride solution. Atmospheric conditions at MSFC did not produce any adverse effects on the material, probably due to the rapid formation of a protective oxide coating. In both the mechanical properties and the stress corrosion evaluations the test specimens which were cut transverse to the rolling direction had superior properties when compared to the longitudinal properties.

  14. Ash deposition and high temperature corrosion at combustion of aggressive fuels

    Energy Technology Data Exchange (ETDEWEB)

    Hede Larsen, O. [I/S Fynsvaerket, Faelleskemikerne, Odense (Denmark); Henriksen, N. [Elsamprojekt A/S, Faelleskemikerne, Fredericia (Denmark)

    1996-12-01

    In order to reduce CO{sub 2} emission, ELSAM is investigating the possibilities of using biomass - mainly straw - for combustion in high efficiency power plants. As straw has very high contents of chlorine and potassium, a fuel with high corrosion and ash deposition propensities has been introduced. ELSAM has investigated 3 ultra supercritical boiler concepts for combustion of straw alone or together with coal: (1) PF boilers with a relatively low share of straw, (2) CFB boilers with low to high share of straw and (3) vibrating grate boilers with 100% straw. These investigations has mainly been full-scale tests with straw fed into existing boilers. Corrosion tests have been performed in these boilers using temperature regulated probes and in-plant test tubes in existing superheaters. The corrosion has been determined by detailed measurements of wall thickness reduction and light optical microscopic measurements of the material degradation due to high temperature corrosion. Corrosion mechanisms have been evaluated using SEM/EDX together with thermodynamical considerations based on measurements of the chemical environment in the flue gas. Ash deposition is problematic in CFB boilers and in straw fired boilers, especially in years with high potassium and chlorine content of the straw. This ash deposition also is related to condensation of KCl and can probably only be handled by improved cleaning devices. (EG)

  15. Corrosion of high temperature alloys in solar salt at 400, 500, and 680ÀC.

    Energy Technology Data Exchange (ETDEWEB)

    Kruizenga, Alan Michael; Gill, David Dennis; LaFord, Marianne Elizabeth

    2013-09-01

    Corrosion tests at 400, 500, and 680ÀC were performed using four high temperature alloys; 347SS, 321SS In625, and HA230. Molten salt chemistry was monitored over time through analysis of nitrite, carbonate, and dissolved metals. Metallography was performed on alloys at 500 and 680ÀC, due to the relatively thin oxide scale observed at 400ÀC. At 500ÀC, corrosion of iron based alloys took the form of chromium depletion and iron oxides, while nickel based alloys also had chromium depletion and formation of NiO. Chromium was detected in relatively low concentrations at this temperature. At 680ÀC, significant surface corrosion occurred with metal losses greater than 450microns/year after 1025hours of exposure. Iron based alloys formed complex iron, sodium, and chromium oxides. Some data suggests grain boundary chromium depletion of 321SS. Nickel alloys formed NiO and metallic nickel corrosion morphologies, with HA230 displaying significant internal oxidation in the form of chromia. Nickel alloys both exhibited worse corrosion than iron based alloys likely due to preferential dissolution of chromium, molybdenum, and tungsten.

  16. High temperature corrosion performance of FeAl intermetallic alloys in molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, M.; Espinosa-Medina, M.A.; Porcayo-Calderon, J.; Martinez, L.; Gonzalez-Rodriguez, J.G

    2003-05-25

    The corrosion performance of FeAl base intermetallic alloys fabricated by spray-atomization and deposition during their immersion in molten sodium metavanadate (NaVO{sub 3}), 80% (wt.%) sodium pentoxide (V{sub 2}O{sub 5}) +20% sodium sulfate (Na{sub 2}SO{sub 4}) and pure Na{sub 2}SO{sub 4} in the temperature range of 600-1000 deg. C during 200 h was investigated. The experiments were realized by the weight loss method in the intermetallic alloys of composition FeAl40(at.%), FeAl40+0.1B and FeAl40+0.1B+10Al{sub 2}O{sub 3}. In all cases, the FeAl40+0.1B+10Al{sub 2}O{sub 3} alloy showed the best corrosion resistance in the temperatures interval studied here. This behavior was discussed in terms of the formation of a protective Al{sub 2}O{sub 3} layer and its dissolution by vanadate phases and internal sulfidation in the case of experiments carried out in pure Na{sub 2}SO{sub 4}. The morphology of the external layers and the corrosion products formed during the tests revealed that the corrosion rate of this type alloy depends on the corrosion compounds that are formed and the development of protective alumina scales.

  17. Thermal Spray Coatings for High-Temperature Corrosion Protection in Biomass Co-Fired Boilers

    Science.gov (United States)

    Oksa, M.; Metsäjoki, J.; Kärki, J.

    2015-01-01

    There are over 1000 biomass boilers and about 500 plants using waste as fuel in Europe, and the numbers are increasing. Many of them encounter serious problems with high-temperature corrosion due to detrimental elements such as chlorides, alkali metals, and heavy metals. By HVOF spraying, it is possible to produce very dense and well-adhered coatings, which can be applied for corrosion protection of heat exchanger surfaces in biomass and waste-to-energy power plant boilers. Four HVOF coatings and one arc sprayed coating were exposed to actual biomass co-fired boiler conditions in superheater area with a probe measurement installation for 5900 h at 550 and 750 °C. The coating materials were Ni-Cr, IN625, Fe-Cr-W-Nb-Mo, and Ni-Cr-Ti. CJS and DJ Hybrid spray guns were used for HVOF spraying to compare the corrosion resistance of Ni-Cr coating structures. Reference materials were ferritic steel T92 and nickel super alloy A263. The circulating fluidized bed boiler burnt a mixture of wood, peat and coal. The coatings showed excellent corrosion resistance at 550 °C compared to the ferritic steel. At higher temperature, NiCr sprayed with CJS had the best corrosion resistance. IN625 was consumed almost completely during the exposure at 750 °C.

  18. High Temperature Corrosion of Superheater Materials for Power Production through Biomass

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Maahn, Ernst emanuel; Nielsen, Karsten agersted

    The aim of the present study has been to establish a fundamental knowledge of the corrosion mechanisms acting on materials for use in biomass fired power plants. The knowledge is created based on laboratory exposures on selected materials in well-defined corrosive gas environments. An experimental...... plant boiler. The experiments using this facility includes corrosion studies of two types of high temperature resistant steels, Sandvik 8LR30 (18Cr 10Ni Ti) and Sanicro 28 (27Cr 31Ni 4Mo)investigated at 600Cin time intervals up to 300 hours. The influence of HCl (200ppm) and of SO2 (300 ppm......) on the corrosion progress has been investigated.In addition the corrosion behaviour of the same materials was investigated after having been exposed under a cover of ash in air in a furnace at temperatures of 525C, 600C and 700C. The ashes utilised are from a straw-fired power plant and a synthetic ash composed...

  19. Green corrosion inhibition of mild steel to aqueous sulfuric acid by the extract of Corchorus olitorius stems

    Science.gov (United States)

    Gobara, Mohamed; Zaghloul, Basem; Baraka, Ahmad; Elsayed, Mohamed; Zorainy, Mahmoud; Mokhtar Kotb, Mohamed; Elnabarawy, Hany

    2017-04-01

    Extract of Corchorus olitorius stems (ECS) was used as a green inhibitor for the inhibition of mild steel corrosion in 0.5 M H2SO4 solution. GC/MS was used for both qualitative and quantitative analysis of the extract. The corrosion performance of the extract was evaluated using electrochemical impedance spectroscopy, potentiodynamic polarization and weight loss. The results showed that ECS is a mixed-type inhibitor which reduces both anodic and cathodic reactions and the inhibition efficiency was reached up to 93%. Adsorption isotherm data was recorded at different temperatures and analyzed by selected adsorption isotherm models to reveal characteristics of inhibition. Thermodynamic calculations showed that the inhibition efficiency increases with increasing inhibitor concentration, and decreases with increasing temperature. Adsorption of ECS on the mild steel surface was found to be spontaneous and exothermic. Adsorption is suggested to be physisorption according to El-Awady isotherm model. Also, the scanning electron microscopy (SEM) was used to investigate the surface morphology to confirm the corrosion results.

  20. Effect of mold temperature on the microstructure and corrosion properties of a 14-karat gold alloy.

    Science.gov (United States)

    Koiso, Kazuo; Saito, Takahiro; Kawashima, Isao

    2012-01-01

    The objective of this research was to investigate the effect of mold temperature on grain interior and grain boundary reactions in a14-karat gold alloy. The alloy (Au-15%Ag-3%Pd-24 mass%Cu) was cast into an investment with different mold temperatures (22, 250,400, and 700°C) and then analyzed using SEM, X-ray diffraction, and potentiodynamic polarization tests. Lower mold temperatures(22 and 250°C) retarded a grain boundary reaction evidently present when using higher mold temperatures (400 and 700°C). Phase separation, which was manifested as a dual phase grain boundary nodular formation, was observed at a higher degree at 400°C mold temperature than at 700°C. The corrosion potentials of alloys cast at lower mold temperatures were more noble than those cast at higher mold temperatures, suggesting improved corrosion properties. Results of this study showed that the microstructure, crystalline phases present, and corrosion properties of 14-karat gold alloy were keenly influenced by the mold temperature, which controls and influences the cooling rate.

  1. High temperature corrosion control and monitoring for processing acidic crudes

    Energy Technology Data Exchange (ETDEWEB)

    Cross, C. [Betz/GE Water and Process Technologies, Woodlands, TX (United States)

    2009-07-01

    The challenge of processing heavy crudes and bitumen in a reliable and economical way was discussed. Many refiners use a conservative approach regarding the rate at which they use discounted crudes or depend upon capital-intensive upgrades to equipment. New strategies based on data-driven decisions are needed in order to obtain the greatest benefit from heavy feedstock. The feasibility of successfully processing more challenging feed can be estimated more accurately by better understanding the interactions between a particular feed and a particular crude unit. This presentation reviewed newly developed techniques that refiners can use to determine the feeds corrosion potential and the probability for this potential to manifest itself in a given crude unit. tabs., figs.

  2. Corrosion of Ferritic Steels in High Temperature Molten Salt Coolants for Nuclear Applications

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J; El-Dasher, B; de Caro, M S; Ferreira, J

    2008-11-25

    Corrosion of ferritic steels in high temperature molten fluoride salts may limit the life of advanced reactors, including some hybrid systems that are now under consideration. In some cases, the steel may be protected through galvanic coupling with other less noble materials with special neutronic properties such a beryllium. This paper reports the development of a model for predicting corrosion rates for various ferritic steels, with and without oxide dispersion strengthening, in FLiBe (Li{sub 2}BeF{sub 4}) and FLiNaK (Li-Na-K-F) coolants at temperatures up to 800 C. Mixed potential theory is used to account for the protection of steel by beryllium, Tafel kinetics are used to predict rates of dissolution as a function of temperature and potential, and the thinning of the mass-transfer boundary layer with increasing Reynolds number is accounted for with dimensionless correlations. The model also accounts for the deceleration of corrosion as the coolants become saturated with dissolved chromium and iron. This paper also reports electrochemical impedance spectroscopy of steels at their corrosion potentials in high-temperature molten salt environments, with the complex impedance spectra interpreted in terms of the interfacial charge transfer resistance and capacitance, as well as the electrolyte conductivity. Such in situ measurement techniques provide valuable insight into the degradation of materials under realistic conditions.

  3. Effect of Temperature on the Corrosion Behavior of API X120 Pipeline Steel in H2S Environment

    Science.gov (United States)

    Okonkwo, Paul C.; Sliem, Mostafa H.; Shakoor, R. A.; Mohamed, A. M. A.; Abdullah, Aboubakr M.

    2017-08-01

    The corrosion behavior of newly developed API X120 C-steel that is commenced to be used for oil pipelines was studied in a H2S saturated 3.5 wt.% NaCl solution between 20 and 60 °C using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The corrosion products formed on the surface of the alloy were characterized using x-ray diffraction and scanning electron microscopy. It has been noticed that the formation of corrosion product layer takes place at both lower and higher temperatures which is mainly comprised of iron oxides and sulfides. The electrochemical results confirmed that the corrosion rate decreases with increasing temperature up to 60 °C. This decrease in corrosion rate with increasing temperature can be attributed to the formation of a protective layer of mackinawite layer. However, cracking in the formed mackinawite layer may not be responsible for the increase in the corrosion rate. More specifically, developed pourbaix diagrams at different temperatures showed that the formed protective layer belongs to mackinawite (FeS), a group of classified polymorphous iron sulfide, which is in good agreement with the experimental results. It is also noticed that the thickness of corrosion products layer increases significantly with decrease in the corrosion rate of API X120 steel exposed to H2S environment. These findings indicate that API X120 C-steel is susceptible to sour corrosion under the above stated experimental conditions.

  4. Development of a new test method of high temperature corrosion in gas turbines based on thermodynamic modelling

    Energy Technology Data Exchange (ETDEWEB)

    Bordenet, B.; Bossmann, H.P. [ALSTOM (Switzerland) Ltd., Baden (Switzerland)

    2004-07-01

    The hot corrosion risk in stationary gas turbines is re-evaluated for the new material combinations and the changed fuel quality. Hot corrosion can only be induced, if the condensation of corrosive species, e.g. sulphates, is possible. The risk of sulphate-induced hot corrosion is directly dependent on the total amount of impurities in the hot gas and the pressure. The evaluation of the risk is done based on thermodynamic modelling of the dew point of the corrosive salts. Based on the theoretical approach a laboratory corrosion test was designed. The test method is based on a salt-spraying test. The exposure is performed in dry air with 300vppm SO{sub 2} and 10vol% H{sub 2}O, with the main test temperatures 700 C and 850 C. The hot corrosion behaviour of three base materials, IN738, CM247 and CMSX-4, and the NiCrAlY-coating SV20 were investigated with the new test method. IN738 exhibited the best corrosion resistance of the base materials, but was also attacked after 500h. The base materials, especially CM247 and CMSX-4, have to be protected by an oxidation- and corrosion-resistant overlay coating in a corrosive environment. They can only be used without a protective coating, when a clean environment can be guaranteed. SV20 has exhibited an excellent corrosion resistance with negligible degradation after 1000 h at 700 and 850 C. (orig.)

  5. Impact of glycolate anion on aqueous corrosion in DWPF and downstream facilities

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J. I. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-12-15

    Glycolic acid is being evaluated as an alternate reductant in the preparation of high level waste for the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS). During processing, the glycolic acid may not be completely consumed with small quantities of the glycolate anion being carried forward to other high level waste (HLW) facilities. The impact of the glycolate anion on the corrosion of the materials of construction (MoC) throughout the waste processing system has not been previously evaluated. A literature review had revealed that corrosion data were not available for the MoCs in glycolic-bearing solutions applicable to SRS systems. Data on the material compatibility with only glycolic acid or its derivative products were identified; however, data were limited for solutions containing glycolic acid or the glycolate anion.

  6. The effect of Co-firing with Straw and Coal on High Temperature Corrosion

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Frandsen, Flemming; Larsen, OH

    2001-01-01

    chloride from the deposit thus chlorination is not a corrosion form that is seen. An increase in straw share from 10 % to 20 % (% energy basis) gave a higher amount of potassium sulphate in the ash and consequently greater amount of sulphidation. At high metal and flue gas temperatures, low temperature hot...... chloride deposited onto superheater sections which causes accelerated corrosion by chlorination. A field investigation at Midtkraft Studstrupværket in Denmark has been undertaken where coal with 10% straw and 20% straw (% energy basis) has been used as fuel for up to 3000 hours. The study was undertaken by......: a) the exposure of metal rings on water/air cooled probes, and b) the exposure of a range of materials built into the existing superheaters. A range of austenitic and ferritic steels was exposed in the steam temperature region of 520-580°C. The flue gas temperature ranged from 925-1100°C...

  7. THE EFFECT OF THE ANNEALING TEMPERATURE ON THE CORROSION RESISTANCE OF WELD JOINT OF AISI 310 STEEL - SHORT COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Pavel Kovačócy

    2011-10-01

    Full Text Available The article presents samples of weld joint of AISI 310 austenitic steel which were subjected to solution annealing at various temperature - time exposures. The objective of the experiment was to determine the annealing temperature so that the steel should not be sensitized. Tendency to intercrystalline corrosion was analysed by means of a corrosion test in 10 % oxalic acid according to ASTM A 262. At the temperatures of 1000 and 1100°C held for 15 min. the steel was not sensitized. At the temperature of 850°C the steel was sensitized, i.e. susceptible to intercrystalline corrosion.

  8. THE EFFECT OF THE ANNEALING TEMPERATURE ON THE CORROSION RESISTANCE OF WELD JOINT OF AISI 310 STEEL - SHORT COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Martina Nerádová

    2012-02-01

    Full Text Available The article presents samples of weld joint of AISI 310 austenitic steel which were subjected to solution annealing at various temperature - time exposures. The objective of the experiment was to determine the annealing temperature so that the steel should not be sensitized. Tendency to intercrystalline corrosion was analysed by means of a corrosion test in 10 % oxalic acid according to ASTM A 262. At the temperatures of 1000 and 1100°C held for 15 min. the steel was not sensitized. At the temperature of 850°C the steel was sensitized, i.e. susceptible to intercrystalline corrosion.

  9. Materials corrosion of high temperature alloys immersed in 600C binary nitrate salt.

    Energy Technology Data Exchange (ETDEWEB)

    Kruizenga, Alan Michael; Gill, David Dennis; LaFord, Marianne Elizabeth

    2013-03-01

    Thirteen high temperature alloys were immersion tested in a 60/40 binary nitrate salt. Samples were interval tested up to 3000 hours at 600ÀC with air as the ullage gas. Chemical analysis of the molten salt indicated lower nitrite concentrations present in the salt, as predicted by the equilibrium equation. Corrosion rates were generally low for all alloys. Corrosion products were identified using x-ray diffraction and electron microprobe analysis. Fe-Cr based alloys tended to form mixtures of sodium and iron oxides, while Fe-Ni/Cr alloys had similar corrosion products plus oxides of nickel and chromium. Nickel based alloys primarily formed NiO, with chromium oxides near the oxide/base alloy interface. In625 exhibited similar corrosion performance in relation to previous tests, lending confidence in comparisons between past and present experiments. HA230 exhibited internal oxidation that consisted of a nickel/chromium oxide. Alloys with significant aluminum alloying tended to exhibit superior performance, due formation of a thin alumina layer. Soluble corrosion products of chromium, molybdenum, and tungsten were also formed and are thought to be a significant factor in alloy performance.

  10. Determining the long-term effects of H₂S concentration, relative humidity and air temperature on concrete sewer corrosion.

    Science.gov (United States)

    Jiang, Guangming; Keller, Jurg; Bond, Philip L

    2014-11-15

    Many studies of sewer corrosion are performed in accelerated conditions that are not representing the actual corrosion processes. This study investigated the effects of various factors over 3.5 years under controlled conditions simulating the sewer environment. Concrete coupons prepared from precorroded sewers were exposed, both in the gas phase and partially submerged in wastewater, in laboratory controlled corrosion chambers. Over the 45 month exposure period, three environmental factors of H2S concentration, relative humidity and air temperature were controlled at different levels in the corrosion chambers. A total of 36 exposure conditions were investigated to determine the long term effects of these factors by regular retrieval of concrete coupons for detailed analysis of surface pH, corrosion layer sulfate levels and concrete loss. Corrosion rates were also determined for different exposure periods. It was found that the corrosion rate of both gas-phase and partially-submerged coupons was positively correlated with the H2S concentration in the gas phase. Relative humidity played also a role for the corrosion activity of the gas-phase coupons. However, the partially-submerged coupons were not affected by humidity as the surfaces of these coupons were saturated due to capillary suction of sewage on the coupon surface. The effect of temperature on corrosion activity varied and possibly the acclimation of corrosion-inducing microbes to temperature mitigated effects of that factor. It was apparent that biological sulfide oxidation was not the limiting step of the overall corrosion process. These findings provide real insights into the long-term effects of these key environmental factors on the sewer corrosion processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Experiences with high temperature corrosion at straw‐firing power plants in Denmark

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Jensen, S. A.; Borg, U.

    2011-01-01

    By the end of 2009, there will be eight biomass and five biomass co‐firing plants in Denmark. Due to the steep increase of corrosion rate with respect to temperature in biomass plants, it is not viable to have similar steam data as fossil fuel plants. Thus for the newer plants, Maribo Sakskøbing...... to enable better lifetime prediction of vulnerable components in straw‐firing plants since the corrosion rates are so much faster than in coal firing plants. Therefore, there are continued investigations in recently commissioned plants with test tubes installed into actual superheaters. In addition...... rates at higher temperatures to assess if there is a possibility to increase the outlet temperature of the plant, thus making the plant more cost effective. For this purpose Avedøre 2 biomass boiler has a test superheater loop fabricated in TP347H FG (the same material as the final superheaters). Some...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-03-31

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

  13. Corrosion of cermet anodes during low temperature electrolysis of alumina. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kozarek, R.L.; Ray, S.P.; Dawless, R.K.; LaCamera, A.F.

    1997-09-26

    Successful development of inert anodes to replace carbon anodes in Hall cells has the potential benefits of lower energy consumption,lower operating costs, and reduced CO{sub 2} and CO emissions. Using inert anodes at reduced current density and reduced operating temperature (800 C) has potential for decreasing the corrosion rate of inert anodes. It may also permit the use of new materials for containment and insulation. This report describes the fabrication characteristics and the corrosion performance of 5324-17% Cu Cermet anodes in 100 hour tests. Although some good results were achieved, the corrosion rate at low temperature (800 C) is varied and not significantly lower than typical results at high temperature ({approximately} 960 C). This report also describes several attempts at 200 hour tests, with one anode achieving 177 hours of continuous operation and another achieving a total of 235 hours but requiring three separate tests of the same anode. The longest run did show a lower wear rate in the last test; but a high resistance layer developed on the anode surface and forced an unacceptably low current density. It is recommended that intermediate temperatures be explored as a more optimal environment for inert anodes. Other electrolyte chemistries and anode compositions (especially high conductivity anodes) should be considered to alleviate problems associated with lower temperature operation.

  14. Pitting corrosion of inconel 600 in chloride and sulfate solutions at low temperature

    Science.gov (United States)

    Chang, Ming-Yu; Yu, Ge-Ping

    1993-06-01

    Pitting corrosion of Inconel 600 was examined in chloride and sulfate solutions through usage of potentiodynamic polarization techniques. The effects of chloride and sulfate concentration were investigated in the range of 0.0001 to 0.1M. Increasing chloride concentrations resulted in active shifts of the pit nucleation potential. Immunity to pitting corrosion was evident at a chloride level below 0.005M. Increasing sulfate concentrations resulted in improved pitting resistance of Inconel 600 in chloride solutions. Detrimental effects associated with pitting were evident with low-level sulfate being added to dilute chloride media. The density of pits increased with increasing chloride concentrations or temperature between room temperature and 70°C. Systematic trends for the depth of pits were not evident. The observations of pitting corrosion in open immersion were consistent with those in polarization methods. Corrosion products contained in the pits were enriched in nickel, chromium and iron with a small amount of titanium and silicon. The enrichment of chlorine or sulfur was still, however, not found.

  15. Effect of temperature on the corrosion inhibition of iron in liquid lead using oxygen inhibitor: studied by MD simulation

    Science.gov (United States)

    Arkundato, Artoto; Monado, Fiber; Su'ud, Zaki

    2017-05-01

    For corrosion mitigation of steels used in a fast nuclear reactor power plant, oxygen gas is one of promising candidates of inhibitors. Many experiments have been conducted to reveal the mechanism of corrosion and mechanism of how to overcome the corrosion. In the previous work, we had shown computationally that the oxygen atom can be used to reduce the corrosion and we had predicted the oxygen contents. In the current work, not only to explore deeeper the ability of oxygen gas to reduce the corrosion, but also to include the variation of used temperature. We still used iron material to represent a real steels. Using MD (molecular dynamics) simulation based on the Lennard-Jones interaction potential, we sought to understand the concentration of oxygen gas as variation of temperature used in the reactor for the best corrosion mitigation. From this work, we conclude that the temperature does not give effect in related with how concentration of injected oxygen. The temparature merely affects to rise the diffusion coefficient of iron in liquid lead, yet it does not influence how much oxygen needed for corrosion mitigation. In this work, all simulations on different series of temperatures (1023°K, 1073°K, 1123°K, 1173°K) reveals that oxygen content of 0.1151wt% will cause the lowest corrosion level of iron in liquid lead.

  16. Aqueous stress-corrosion cracking of high-toughness D6AC steel

    Science.gov (United States)

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

    1976-01-01

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

  17. Dissolution and Protection of Aluminium Oxide in Corrosive Aqueous Media - An Ellipsometry and Reflectometry Study

    NARCIS (Netherlands)

    Karlsson, P.M.; Postmus, B.R.; Palmqvist, A.E.C.

    2009-01-01

    Dissolution of alumina has been studied from wafers in aqueous solution by means of ellipsometry and reflectometry. It was discovered that the dissolution of aluminium oxide is promoted by ethanol amines like N,N-bis(2-hydroxyethyl)glycine and triethanolamine, and that this dissolution is retarded

  18. Effect of Temperature on the Galvanic Corrosion of Cu-Ni Alloy/High Strength Steel in Seawater

    Directory of Open Access Journals (Sweden)

    Wang Chun Li

    2016-01-01

    Full Text Available The galvanic corrosion behavior of Cu-Ni Alloy(B10/high strength steel (921A has been studied using a zero-resistance ammeter (ZRA in seawater at different temperatures. As well as it was systemically investigated by weight loss measurements, electrochemical methods and scanning electron microscope.Results showed 921A acts as the anode and B10 act as the cathodes. The effect of temperature on the galvanic corrosion is important, the corrosion rate became higher with the temperature increased.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-15

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

  20. Corrosion Behavior of NiCrFe Alloy 600 in High Temperature, Hydrogenated Water

    Energy Technology Data Exchange (ETDEWEB)

    SE Ziemniak; ME Hanson

    2004-11-02

    The corrosion behavior of Alloy 600 (UNS N06600) is investigated in hydrogenated water at 260 C. The corrosion kinetics are observed to be parabolic, the parabolic rate constant being determined by chemical descaling to be 0.055 mg dm{sup -2} hr{sup -1/2}. A combination of scanning and transmission electron microscopy, supplemented by energy dispersive X-ray spectroscopy and grazing incidence X-ray diffraction, are used to identify the oxide phases present (i.e., spinel) and to characterize their morphology and thickness. Two oxide layers are identified: an outer, ferrite-rich layer and an inner, chromite-rich layer. X-ray photoelectron spectroscopy with argon ion milling and target factor analysis is applied to determine spinel stoichiometry; the inner layer is (Ni{sub 0.7}Fe{sub 0.3})(Fe{sub 0.3}Cr{sub 0.7}){sub 2}O{sub 4}, while the outer layer is (Ni{sub 0.9}Fe{sub 0.1})(Fe{sub 0.85}Cr{sub 0.15}){sub 2}O{sub 4}. The distribution of trivalent iron and chromium cations in the inner and outer oxide layers is essentially the same as that found previously in stainless steel corrosion oxides, thus confirming their invariant nature as solvi in the immiscible spinel binary Fe{sub 3}O{sub 4}-FeCr{sub 2}O{sub 4} (or NiFe{sub 2}O{sub 4}-NiCr{sub 2}O{sub 4}). Although oxidation occurred non-selectively, excess quantities of nickel(II) oxide were not found. Instead, the excess nickel was accounted for as recrystallized nickel metal in the inner layer, as additional nickel ferrite in the outer layer, formed by pickup of iron ions from the aqueous phase, and by selective release to the aqueous phase.

  1. Impact of Glycolate Anion on Aqueous Corrosion in DWPF and Downstream Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-07-12

    Glycolic acid is being evaluated as an alternate reductant in the preparation of high level waste for the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS). During processing, the glycolic acid may not be completely consumed with small quantities of the glycolate anion being carried forward to other high level waste (HLW) facilities. The SRS liquid waste contractor requested an assessment of the impact of the glycolate anion on the corrosion of the materials of construction (MoC) throughout the waste processing system since this impact had not been previously evaluated. A literature review revealed that corrosion data were not available for the MoCs in glycolic-bearing solutions applicable to SRS systems. Data on the material compatibility with only glycolic acid or its derivative products were identified; however, data were limited for solutions containing glycolic acid or the glycolate anion. For the proprietary coating systems applied to the DWPF concrete, glycolic acid was deemed compatible since the coatings were resistant to more aggressive chemistries than glycolic acid. Additionally similar coating resins showed acceptable resistance to glycolic acid.

  2. Impact of Glycolate Anion on Aqueous Corrosion in DWPF and Downstream Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-11-20

    Glycolic acid is being evaluated as an alternate reductant in the preparation of high level waste for the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS). During processing, the glycolic acid may not be completely consumed with small quantities of the glycolate anion being carried forward to other high level waste (HLW) facilities. The SRS liquid waste contractor requested an assessment of the impact of the glycolate anion on the corrosion of the materials of construction (MoC) throughout the waste processing system since this impact had not been previously evaluated. A literature review revealed that corrosion data were not available for the MoCs in glycolic-bearing solutions applicable to SRS systems. Data on the material compatibility with only glycolic acid or its derivative products were identified; however, data were limited for solutions containing glycolic acid or the glycolate anion. For the proprietary coating systems applied to the DWPF concrete, glycolic acid was deemed compatible since the coatings were resistant to more aggressive chemistries than glycolic acid. Additionally, similar coating resins showed acceptable resistance to glycolic acid.

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

    OpenAIRE

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

    2012-01-01

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

  4. Lifetime evaluation of superheater tubes exposed to steam oxidation, high temperature corrosion and creep

    Energy Technology Data Exchange (ETDEWEB)

    Henriksen, N. [Elsamprojekt A/S, Faelleskemikerne, Fredericia (Denmark); Hede Larsen, O.; Blum, R. [I/S Fynsvaerket, Faelleskemikerne, Odense (Denmark)

    1996-12-01

    Advanced fossil fired plants operating at high steam temperatures require careful design of the superheaters. The German TRD design code normally used in Denmark is not precise enough for the design of superheaters with long lifetimes. The authors have developed a computer program to be used in the evaluation of superheater tube lifetime based on input related to tube dimensions, material, pressure, steam temperature, mass flux, heat flux and estimated corrosion rates. The program is described in the paper. As far as practically feasible, the model seems to give a true picture of the reality. For superheaters exposed to high heat fluxes or low internal heat transfer coefficients as is the case for superheaters located in fluidized bed environments or radiant environments, the program has been extremely useful for evaluation of surface temperature, oxide formation and lifetime. The total uncertainty of the method is mainly influenced by the uncertainty of the determination of the corrosion rate. More precise models describing the corrosion rate as a function of tube surface temperature, fuel parameters and boiler parameters need to be developed. (au) 21 refs.

  5. A study on structural analysis of highly corrosive melts at high temperature

    CERN Document Server

    Ohtori, N

    2002-01-01

    When sodium is burned at high temperature in the atmosphere, it reacts simultaneously with H sub 2 O in the atmosphere so that it can produce high temperature melt of sodium hydroxide as a solvent. If this melt includes peroxide ion (O sub 2 sup 2 sup -), it will be a considerably active and corrosive for iron so that several sodium iron double oxides will be produced as corrosion products after the reaction with steel structures. The present study was carried out in order to investigate the ability of presence of peroxide ion in sodium hydroxide solvent at high temperature and that of identification of the several corrosion products using laser Raman spectroscopy. The measurement system with ultraviolet laser was developed simultaneously in the present work to improve the ability of the measurement at high temperature. As results from the measurements, the possibility of the presence of peroxide ion was shown up to 823K in sodium peroxide and 823K in the melt of sodium hydroxide mixed with sodium peroxide. A...

  6. Influence of turbulent flow on the corrosion kinetics of API X52 pipeline steel in aqueous solutions containing H{sub 2}S

    Energy Technology Data Exchange (ETDEWEB)

    Galvan-Martinez, Ricardo; Genesca-Llongueras, Juan [Departamento Ingenieria Metalurgica, Facultad Quimica, Universidad Nacional Autonoma de Mexico, UNAM, Ciudad Universitaria, 04510 Mexico D.F. (Mexico); Mendoza-Flores, Juan; Duran-Romero, Ruben [Corrosion, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, 07730 Mexico D.F. (Mexico)

    2004-07-01

    A corrosion process can be influenced by the relative movement between the corroding environment and the metal. This relative movement could increase the heat transfer and the mass transfer of reactants towards and from the surface of the corroding metal, with a consequent increase in the corrosion rate. Also, if solid particles are present, removal of protective films, erosion and wear can occur on the metallic surface. Many industrial processes involve the movement of corrosive liquids in close contact to metallic structures. Therefore, the influence of flow on the corrosion processes is an important issue to be considered in the design and operation of industrial equipment. This influence is complex and many variables are involved. Several observations of flow-accelerated corrosion problems have been documented, particularly in the oil and gas industries, where the combined effect of flow and dissolved gases, such as hydrogen sulphide (H{sub 2}S) and carbon dioxide (CO{sub 2}), is important. Turbulent flow conditions are commonly found in industrial processes. However, few corrosion studies in controlled turbulent flow conditions are available. With the increasing necessity to describe the corrosion of metals in turbulent flow conditions some laboratory hydrodynamic systems have been used with different degrees of success. The use of the rotating cylinder electrode (RCE), as a laboratory hydrodynamic test system, has gained popularity in corrosion studies. This popularity is due to its characteristics, such as, its operation mainly at turbulent flow conditions; its well understood mass transfer properties and its easiness of construction and operation. The aim of the present work is to explore the effect that turbulent flow conditions have on the electrochemical kinetics of steel samples immersed in aqueous environments containing H{sub 2}S. In order to control the turbulent flow conditions in the laboratory, a rotating cylinder electrode (RCE) was used. In

  7. 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.

  8. Literature Survey on the Stress Corrosion Cracking of Low-Alloy Steels in High Temperature Water

    Energy Technology Data Exchange (ETDEWEB)

    Seifert, H.P

    2002-02-01

    The present report is a summary of a literature survey on the stress corrosion cracking (SCC) behaviour/ mechanisms in low-alloy steels (LAS) in high-temperature water with special emphasis to primary-pressure-boundary components of boiling water reactors (BWR). A brief overview on the current state of knowledge concerning SCC of low-alloy reactor pressure vessel and piping steels under BWR conditions is given. After a short introduction on general aspects of SCC, the main influence parameter and available quantitative literature data concerning SCC of LAS in high-temperature water are discussed on a phenomenological basis followed by a summary of the most popular SCC models for this corrosion system. The BWR operating experience and service cracking incidents are discussed with respect to the existing laboratory data and background knowledge. Finally, the most important open questions and topics for further experimental investigations are outlined. (author)

  9. Effect of Mn Content and Solution Annealing Temperature on the Corrosion Resistance of Stainless Steel Alloys

    Directory of Open Access Journals (Sweden)

    Ihsan-ul-Haq Toor

    2014-01-01

    Full Text Available The corrosion behavior of two specially designed austenitic stainless steels (SSs having different Nickel (Ni and Manganese (Mn contents was investigated. Prior to electrochemical tests, SS alloys were solution-annealed at two different temperatures, that is, at 1030°C for 2 h and 1050°C for 0.5 h. Potentiodynamic polarization (PD tests were carried out in chloride and acidic chloride, whereas linear polarization resistance (LPR and electrochemical impedance spectroscopy (EIS was performed in 0.5 M NaCl solution at room temperature. SEM/EDS investigations were carried out to study the microstructure and types of inclusions present in these alloys. Experimental results suggested that the alloy with highest Ni content and annealed at 1050°C/0.5 hr has the highest corrosion resistance.

  10. Duplex Al-based thermal spray coatings for corrosion protection in high temperature refinery applications

    Directory of Open Access Journals (Sweden)

    Adriana da Cunha Rocha

    2004-03-01

    Full Text Available The application of thermal spray coatings has been effective in preventing corrosion of steel and iron products. It has been used in a wide range of applications spreading from the petroleum to the food industry. In this work, the performance and effectiveness of a two-layered aluminum-based thermal spray coating applied to an ASTM A387 G11 steel was evaluated. The coating structure was comprised of an inner Al-Fe-Cr layer and an outer layer of aluminum. Coated samples were tested in the reactor zone of a fluid catalytic cracking unit (FCCU of a petrochemical plant for 2.5 years. The reactor zone temperature was about 793 K (520 °C and the environment was a mixed gas containing sulfur, oxygen and carbon. Laboratory-scale tests were also conducted on the coated samples in order to gain a better understanding of the corrosive effect of the gaseous species present in the FCCU atmosphere. Porosity present in the thermal spray coatings allowed the penetration of the atmosphere corrodents, which instigated intergranular corrosion of the steel substrate. The presence of an inner Al-Fe-Cr layer did not prevent coating spallation, which further contributed to the internal corrosion process.

  11. High temperature corrosion of advanced ceramic materials for hot-gas filters and heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Kupp, E.R.; Trubelja, M.F.; Spear, K.E.; Tressler, R.E. [Pennsylvania State Univ., University Park, PA (United States)

    1995-08-01

    Experimental corrosion studies of hot gas filter materials and heat exchanger materials in oxidizing combustion environments have been initiated. Filter materials from 3M Co. and DuPont Lanxide Composites Inc. are being tested over a range of temperatures, times and gas flows. It has been demonstrated that morphological and phase changes due to corrosive effects occur after exposure of the 3M material to a combustion environment for as little as 25 hours at 800{degrees}C. The study of heat exchanger materials has focused on enhancing the corrosion resistance of DuPont Lanxide Dimox{trademark} composite tubes by adding chromium to its surfaces by (1) heat treatments in a Cr{sub 2}O{sub 3} powder bed, or (2) infiltrating surface porosity with molten chromium nitrate. Each process is followed by a surface homogenization at 1500{degrees}C. The powder bed method has been most successful, producing continuous Cr-rich layers with thicknesses ranging from 20 to 250 {mu}m. As-received and Cr-modified DuPont Lanxide Dimox{trademark} samples will be reacted with commonly encountered coal-ash slags to determine the Cr effects on corrosion resistance.

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

    Energy Technology Data Exchange (ETDEWEB)

    Afshari, V., E-mail: vafshari@ut.ac.ir [School of Metallurgy and Materials Engineering, University College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Dehghanian, C. [School of Metallurgy and Materials Engineering, University College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of)

    2010-11-01

    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{sup -1} NaCl + 70 mg L{sup -1} Na{sub 2}SO{sub 4}. 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.

  13. Effect of the deposition temperature on corrosion resistance and biocompatibility of the hydroxyapatite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Vladescu, A., E-mail: alinava@inoe.ro [National Institute for Optoelectronics, 409 Atomistilor Str., Magurele (Romania); Braic, M. [National Institute for Optoelectronics, 409 Atomistilor Str., Magurele (Romania); Azem, F. Ak [Dokuz Eylul University, Engineering Faculty, Metallurgical and Materials Engineering Department, Buca-Izmir (Turkey); Titorencu, I. [Institute of Cellular Biology and Pathology Nicolae Simionescu of the Romanian Academy, 8 B.P.Hasdeu, Bucharest (Romania); Braic, V. [National Institute for Optoelectronics, 409 Atomistilor Str., Magurele (Romania); Pruna, V. [Institute of Cellular Biology and Pathology Nicolae Simionescu of the Romanian Academy, 8 B.P.Hasdeu, Bucharest (Romania); Kiss, A. [National Institute for Optoelectronics, 409 Atomistilor Str., Magurele (Romania); Parau, A.C.; Birlik, I. [Dokuz Eylul University, Engineering Faculty, Metallurgical and Materials Engineering Department, Buca-Izmir (Turkey)

    2015-11-01

    Highlights: • Hydroxyapatite has been produced at temperature from 400 to 800 °C by magnetron sputtering. • Hydroxyapatite crystallinity is improved by increasing substrate temperature. • The increase of substrate temperature resulted in corrosion resistance increasing. • The coating shows high growth of the osteosarcoma cells over a wide temperature range. - Abstract: Hydroxyapatite (HAP) ceramics belong to a class of calcium phosphate-based materials, which have been widely used as coatings on titanium medical implants in order to improve bone fixation and thus to increase the lifetime of the implant. In this study, HAP coatings were deposited from pure HAP targets on Ti6Al4V substrates using the radio-frequency magnetron sputtering technique at substrate temperatures ranging from 400 to 800 °C. The surface morphology and the crystallographic structure of the films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion resistance of the coatings in saliva solution at 37 °C was evaluated by potentiodynamic polarization. Additionally, the human osteosarcoma cell line (MG-63) was used to test the biocompatibility of the coatings. The results showed that all of the coatings grown uniformly and that the increasing substrate temperature induced an increase in their crystallinity. Corrosion performance of the coatings was improved with the increase of the substrate temperature from 400 °C to 800 °C. Furthermore, all the coatings support the attachment and growth of the osteosarcoma cells with regard to the in vitro test findings.

  14. Kinetics of Corrosion Process in H2SO4 and HNO3 Aqueous Solutions of Lead Free Sn-Ag-Cu Solder Alloys

    Directory of Open Access Journals (Sweden)

    Guśpiel J.

    2016-06-01

    Full Text Available This paper presents the results of the corrosion resistance of Sn-Ag-Cu alloys in air-saturated aqueous solutions containing NO3-, SO42- ions, whose concentration was equivalent to their contents in acid rains and in concentrations 10 - 100 times higher. The Ag, Cu and Sn concentrations in the corrosive media were determined using the Atomic Absorption Spectrometry. The specific dissolution rate and corrosion current were derived using the a rotating disc technique. The corrosion rate of Sn- Ag-Cu alloys depends on pH of the examined solutions and on the concentration of oxygen near the phase boundary. In the whole range of concentrations of the applied H2SO4 + HNO3 mixtures of acids, the pure Sn was more corrosion resistant than eutectic alloy as well as the near eutectic one, following the sequence: Sn>Sn3.66Ag0.91Cu>3.8Ag0.7Cu.

  15. Stress Corrosion Behavior of Low-temperature Liquid-Nitrided 316 Austenitic Stainless Steel in a Sour Environment

    Science.gov (United States)

    Zhang, Xiangfeng; Wang, Jun; Fan, Hongyuan; Yan, Jing; Duan, Lian; Gu, Tan; Xian, Guang; Sun, Lan; Wang, Danqi

    2017-10-01

    Low-temperature nitridation is a widely used surface heat treatment. Low-temperature liquid nitridation was applied to 316 austenitic stainless steel and an S-phase (expanded austenite) layer was achieved on the alloy surface. The effect of the S-phase layer on corrosion resistance and stress corrosion cracking was investigated in a sour environment. When a bending stress of 164 MPa (80 pct yield stress, YS) was applied, no macroscopic corrosion cracking and pits were observed on the nitrided samples and the S-phase layer stayed intact. Although no macroscopic corrosion cracking was observed on the non-nitrided samples under 205 MPa (100 pct YS), some pits were formed on the alloy surface. This could be attributed to the high stresses and hardness, and the excellent corrosion resistance of the S-phase layer introduced by low-temperature nitridation. Supersaturated nitrogen atoms in the S-phase layer can effectively prevent the decrease in pH of the corrosive medium and accelerate the alloy repassivation kinetics. However, when the bending stress was increased to 205 and 246 MPa (100 pct YS, 120 pct YS), macroscopic cracks were observed in the presence of both tensile stress and a corrosive medium.

  16. Stress Corrosion Behavior of Low-temperature Liquid-Nitrided 316 Austenitic Stainless Steel in a Sour Environment

    Science.gov (United States)

    Zhang, Xiangfeng; Wang, Jun; Fan, Hongyuan; Yan, Jing; Duan, Lian; Gu, Tan; Xian, Guang; Sun, Lan; Wang, Danqi

    2018-01-01

    Low-temperature nitridation is a widely used surface heat treatment. Low-temperature liquid nitridation was applied to 316 austenitic stainless steel and an S-phase (expanded austenite) layer was achieved on the alloy surface. The effect of the S-phase layer on corrosion resistance and stress corrosion cracking was investigated in a sour environment. When a bending stress of 164 MPa (80 pct yield stress, YS) was applied, no macroscopic corrosion cracking and pits were observed on the nitrided samples and the S-phase layer stayed intact. Although no macroscopic corrosion cracking was observed on the non-nitrided samples under 205 MPa (100 pct YS), some pits were formed on the alloy surface. This could be attributed to the high stresses and hardness, and the excellent corrosion resistance of the S-phase layer introduced by low-temperature nitridation. Supersaturated nitrogen atoms in the S-phase layer can effectively prevent the decrease in pH of the corrosive medium and accelerate the alloy repassivation kinetics. However, when the bending stress was increased to 205 and 246 MPa (100 pct YS, 120 pct YS), macroscopic cracks were observed in the presence of both tensile stress and a corrosive medium.

  17. Improved corrosion protection of aluminum alloys by low-temperature plasma interface engineering

    Science.gov (United States)

    Reddy, Chandra Mudupu

    The System Approach Interface Engineering (SAIE) concept was employed to develop corrosion protection processes for aluminum (Al) alloys by application of a low temperature plasma interface engineering technique with a cathodic electrocoat (E-coat) as the primary layer coating. The SAIE concept emphasizes that the corrosion protection property of the coated system for Al alloys depends on the total system rather than any good corrosion protection component of the system. The cathodic E-coated SAIE plasma pretreatments on Alclad 2024-T3, 2024-T3 bare and 7075-T6 bare alloys showed excellent corrosion resistance property when tested by SO2 and Prohesion salt spray tests. These systems out performed the conventional conversion coated controls, chromate conversion coated then Deft primer coated (CC Deft) and chromate conversion coated then cathodic E-coated (CC E-coat) in both the corrosion testes. The corrosion protection by SAIE systems depends on three major factors; (1) improved barrier characteristics of E-coat, (2) water insensitive adhesion of E-coat to plasma polymers deposited in a DC discharge and (3) creating a stable surface oxide layer by plasma treatment or chemical cleaning. Different chemical pretreatments were employed to create a stable barrier type aluminum oxide layer on the surfaces of the substrates prior to plasma polymer deposition. The surface analysis showed that these pretreatments depend on the type of alloy and surface chemistry. As received surfaces with acetone wipe and plasma cleaning of the organic contaminants was found to be best for Alclad 2024-T3 alloy. Chemical alkaline cleaning for 2024-T3 bare and alkaline cleaning followed by deoxidization for 7075-T6 bare alloy were necessary. The adhesion of the cathodic E-coat was improved by surface energy matching techniques by deposition of various plasma polymer films of trimethylsilane (TMS) and mixtures of TMS with O2, H2, and N2. The adhesion performance evaluated by the N

  18. A new architecture for a factual materials database on coatings and high temperature corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Streiff, R.; Vaugelade, S. [Univ. de Provence, Marseille (France); Komornicki, S. [Akademia Gorniczo-Hutnicza, Cracow (Poland); Boone, D.H. [Boone and Associates, Walnut Creek, CA (United States)

    1997-12-31

    C and HTC-DATA a data bank on coatings and high temperature corrosion, has been created to help in choosing coatings for specific applications, knowing their fabrication process characteristics and their protectivity characteristics. This relational data bank will include five databases, viz. (1) a bibliographic reference data base, (2) a directory of addresses of companies and researchers involved in the field, (3) a numerical database on alloy composition, (4) a factual coatings database, and (5) a factual corrosion database. Building of these factual databases first followed the classical MERISE analytical treatment for data organisation. However, the variety of coating characteristics has resulted in a very complex database structure with a very large number of tables and fields. Therefore, a new approach for the architecture of the coating database based upon a thesaurus to describe the data has been perfected which is presented in this paper. (orig.) 13 refs.

  19. High Temperature Corrosion of Inconel 600 in NaCl-KCl Molten Salts

    Directory of Open Access Journals (Sweden)

    G. Salinas-Solano

    2014-01-01

    Full Text Available In this work the corrosion resistance of a high content nickel alloy, Inconel 600, was investigated in mixed NaCl-KCl salts at 700, 800, and 900°C for 100 hours in static air. Investigation was carried out using electrochemical techniques such as polarization curves, rest potential measurements, linear polarization resistance, and electrochemical impedance spectroscopy. Corroded specimens were analyzed by scanning electron microscopy (SEM and energy-dispersive X-ray spectroscopy (EDS. Electrochemical measurements showed an increased degradation rate of Inconel 600 with increasing test temperature. SEM and EDS analysis show that the damage experienced by Inconel 600 is greater than that determined by electrochemical measurements. This damage was identified as internal corrosion due to the reaction of Cl2 with the alloying elements (Cr and Fe; however, at 900°C the internal damage was minor and it was associated with the nickel content in the alloy.

  20. Effect of Water Vapor on High-Temperature Corrosion under Conditions Mimicking Biomass Firing

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2015-01-01

    The variable flue gas composition in biomass-fired plants, among other parameters, contributes to the complexityof high-temperature corrosion of materials. Systematic parameter studies are thus necessary to understand the underlyingcorrosion mechanisms. This paper investigates the effect of water...... atmospherecontaining either 3 or 13 vol % H2O vapor. Comprehensive characterization of the corrosion products was carried out by thecomplementary use of microscopic, spectroscopic, and diffraction-based techniques. To evaluate the effect of the exposure time,results were compared to previous results with longer...... isothermal exposure over 168 h and indicated that the development of aNi-rich layer as a result of selective attack was time-dependent. The increase in the water vapor decreased the measurablecorrosion attack, and in addition, decreased sulfation was observed. Results from the current investigation and from...

  1. 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.

  2. The effects of temperature and aeration on the corrosion of A508III low alloy steel in boric acid solutions at 25–95 °C

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Qian [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Mailbox 269, 149 Yanchang Road, Shanghai, 200072 (China); State Key Laboratory of Advanced Special Steel, Shanghai University, 149 Yanchang Road, Shanghai, 200072 (China); Lu, Zhanpeng, E-mail: zplu@t.shu.edu.cn [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Mailbox 269, 149 Yanchang Road, Shanghai, 200072 (China); State Key Laboratory of Advanced Special Steel, Shanghai University, 149 Yanchang Road, Shanghai, 200072 (China); Shanghai Key Laboratory of Advanced Ferrometallurgy, Shanghai University, 149 Yanchang Road, Shanghai, 200072 (China); Chen, Junjie [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Mailbox 269, 149 Yanchang Road, Shanghai, 200072 (China); State Key Laboratory of Advanced Special Steel, Shanghai University, 149 Yanchang Road, Shanghai, 200072 (China); Yao, Meiyi [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Mailbox 269, 149 Yanchang Road, Shanghai, 200072 (China); State Key Laboratory of Advanced Special Steel, Shanghai University, 149 Yanchang Road, Shanghai, 200072 (China); Shanghai Key Laboratory of Advanced Ferrometallurgy, Shanghai University, 149 Yanchang Road, Shanghai, 200072 (China); Chen, Zhen; Ejaz, Ahsan [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Mailbox 269, 149 Yanchang Road, Shanghai, 200072 (China)

    2016-11-15

    The effects of temperature, solution composition and dissolved oxygen on the corrosion rate and electrochemical behavior of an A508III low alloy steel in boric acid solution with lithium hydroxide at 25–95 °C are investigated. In aerated solutions, increasing the boric acid concentration increases the corrosion rate and the anodic current density. The corrosion rate in deaerated solutions increases with increasing temperature. A corrosion rate peak value is found at approximately 75 °C in aerated solutions. Increasing temperature increases the oxygen diffusion coefficient, decreases the dissolved oxygen concentration, accelerates the hydrogen evolution reaction, and accelerates both the active dissolution and the film forming reactions. Increasing dissolved oxygen concentration does not significantly affect the corrosion rate at 50 and 60 °C, increases the corrosion rate at 70 and 80 °C, and decreases the corrosion rate at 87.5 and 95 °C in a high concentration boric acid solution with lithium hydroxide. - Highlights: • Effects of temperature on the corrosion of LAS in simulated PWR water are studied. • Increase of corrosion rate with increasing temperature in deaerated solution is observed. • Corrosion rate peaks at approximately 75 °C in aerated solution. • Deaeration decreases the corrosion rate in concentrated PWR water at 70–80 °C. • Deaeration increases the corrosion rate in concentrated PWR water at 87.5–95 °C.

  3. 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

  4. Effects of temperature and pressure on stress corrosion cracking behavior of 310S stainless steel in chloride solution

    Science.gov (United States)

    Zhong, Yunpan; Zhou, Cheng; Chen, Songying; Wang, Ruiyan

    2017-01-01

    310S is an austenitic stainless steel for high temperature applications, having strong resistance of oxidation, hydrogen embrittlement and corrosion. Stress corrosion cracking(SCC) is the main corrosion failure mode for 310S stainless steel. Past researched about SCC of 310S primarily focus on the corrosion mechanism and influence of temperature and corrosive media, but few studies concern the combined influence of temperature, pressure and chloride. For a better understanding of temperature and pressure's effects on SCC of 310S stainless steel, prepared samples are investigated via slow strain rate tensile test(SSRT) in different temperature and pressure in NACE A solution. The result shows that the SCC sensibility indexes of 310S stainless steel increase with the rise of temperature and reach maximum at 10MPa and 160°C, increasing by 22.3% compared with that at 10 MPa and 80 °C. Instead, the sensibility decreases with the pressure up. Besides, the fractures begin to transform from the ductile fracture to the brittle fracture with the increase of temperature. 310S stainless steel has an obvious tendency of stress corrosion at 10MPa and 160°C and the fracture surface exists cleavage steps, river patterns and some local secondary cracks, having obvious brittle fracture characteristics. The SCC cracks initiate from inclusions and tiny pits in the matrix and propagate into the matrix along the cross section gradually until rupture. In particular, the oxygen and chloride play an important role on the SCC of 310S stainless steel in NACE A solution. The chloride damages passivating film, causing pitting corrosion, concentrating in the cracks and accelerated SSC ultimately. The research reveals the combined influence of temperature, pressure and chloride on the SCC of 310S, which can be a guide to the application of 310S stainless steel in super-heater tube.

  5. Mechanism of Na2SO4-induced corrosion of molybdenum containing nickel-base superalloys at high temperatures. I - Corrosion in atmospheres containing O2 only. II - Corrosion in O2 + SO2 atmospheres

    Science.gov (United States)

    Misra, A. K.

    1986-01-01

    Kinetics of the Na2SO4-induced corrosion of the molybdenum-containing nickel-base superalloys, B-1900 and Udimet 700, coated with Na2MoO4, has been studied in oxygen atmosphere at temperatures ranging from 750 to 950 C. Because the gas turbine atmosphere always contains some SO2 and SO3, the effect of atmospheric SO2 content on corrosion of Udimet-700 has also been studied. It was found that in the O2 atmosphere the melt in the catastrophic corrosion phase consists of Na2MoO4 plus MoO3, with the onset of the catastrophic corrosion coinciding with the appearance of MoO3. In the presence of low levels of atmospheric SO2 (below 0.24 percent), the melt during catastrophic corrosion contains, in addition to Na2MoO4 and MoO3, some quantities of Na2SO4. At the levels of SO2 above 1 percent, no catastrophic corrosion was observed. At these SO2 levels, internal sulfidation appears to be the primary mode of degradation.

  6. Thermal Cycling and High-Temperature Corrosion Tests of Rare Earth Silicate Environmental Barrier Coatings

    Science.gov (United States)

    Darthout, Émilien; Gitzhofer, François

    2017-12-01

    Lutetium and yttrium silicates, enriched with an additional secondary zirconia phase, environmental barrier coatings were synthesized by the solution precursor plasma spraying process on silicon carbide substrates. A custom-made oven was designed for thermal cycling and water vapor corrosion testing. The oven can test four specimens simultaneously and allows to evaluate environmental barrier performances under similar corrosion kinetics compared to turbine engines. Coatings structural evolution has been observed by SEM on the polished cross sections, and phase composition has been analyzed by XRD. All coatings have been thermally cycled between 1300 °C and the ambient temperature, without spallation, due to their porosity and the presence of additional secondary phase which increases the thermal cycling resistance. During water vapor exposure at 1200 °C, rare earth disilicates showed a good stability, which is contradictory with the literature, due to impurities—such as Si- and Al-hydroxides—in the water vapor jets. The presence of vertical cracks allowed the water vapor to reach the substrate and then to corrode it. It has been observed that thin vertical cracks induced some spallation after 24 h of corrosion.

  7. Thermal Cycling and High-Temperature Corrosion Tests of Rare Earth Silicate Environmental Barrier Coatings

    Science.gov (United States)

    Darthout, Émilien; Gitzhofer, François

    2017-09-01

    Lutetium and yttrium silicates, enriched with an additional secondary zirconia phase, environmental barrier coatings were synthesized by the solution precursor plasma spraying process on silicon carbide substrates. A custom-made oven was designed for thermal cycling and water vapor corrosion testing. The oven can test four specimens simultaneously and allows to evaluate environmental barrier performances under similar corrosion kinetics compared to turbine engines. Coatings structural evolution has been observed by SEM on the polished cross sections, and phase composition has been analyzed by XRD. All coatings have been thermally cycled between 1300 °C and the ambient temperature, without spallation, due to their porosity and the presence of additional secondary phase which increases the thermal cycling resistance. During water vapor exposure at 1200 °C, rare earth disilicates showed a good stability, which is contradictory with the literature, due to impurities—such as Si- and Al-hydroxides—in the water vapor jets. The presence of vertical cracks allowed the water vapor to reach the substrate and then to corrode it. It has been observed that thin vertical cracks induced some spallation after 24 h of corrosion.

  8. Influence of the solution temperature on the corrosion behavior of an austenitic stainless steel in phosphoric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez-Ferrandiz, M.V.; Blasco-Tamarit, E.; Garcia-Garcia, D.M.; Garcia-Anton, J. [Valencia Univ. Politecnica, Dept. de Ingenieria Quimica y Nuclear. ETSI Industriales, Valencia (Spain); Guenbour, A.; Bakour, S.; Benckokroun, A. [University Mohammed V-Agdal, Lab. Corrosion-Electrochimie, Faculty of Sciences, Rabat (Morocco)

    2009-07-01

    The objective of the present work is to study the effect of the solution temperature on the corrosion resistance of a highly alloyed austenitic stainless steel (UNS N08031) used as base metal, the welded metal obtained by TIG (Tungsten Inert Gas) welding using a Nickel-base alloy (UNS N06059) as filler metal, and the Heat Affected Zone (HAZ) of the base metal. The materials were tested in 5.5 M phosphoric acid solution at 25 C, 40 C, 60 C and 80 C. Open Circuit Potential tests and potentiodynamic anodic polarization curves have been carried out to obtain information about the electrochemical behavior of the materials. Corrosion potentials and corrosion current densities were obtained from Tafel analysis. The critic potentials and passivation current densities of the studied materials were also analyzed. The galvanic corrosion generated by the electrical contact between the welded metal, the base metal and the HAZ, was estimated from the polarisation diagrams according to the Mixed Potential Theory. The samples were etched to study their microstructure by Optical Microscopy. Results demonstrated that the corrosion potential values shift to more anodic potentials as temperature increases. The corrosion current densities and the passive current densities increased with temperature. Open circuit potential values were located in the passive zone of the potentiodynamic curves, which means that the materials passivated spontaneously. (authors)

  9. High temperature alkali corrosion of ceramics in coal gas: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Pickrell, G.R.; Sun, T.; Brown, J.J. Jr.

    1994-12-31

    There are several ceramic materials which are currently being considered for use as structural elements in coal combustion and coal conversion systems because of their thermal and mechanical properties. These include alumina (refractories, membranes, heat engines); silicon carbide and silicon nitride (turbine engines, internal combustion engines, heat exchangers, particulate filters); zirconia (internal combustion engines, turbine engines, refractories); and mullite and cordierite (particulate filters, refractories, heat exchangers). High temperature alkali corrosion has been known to cause premature failure of ceramic components used in advanced high temperature coal combustion systems such as coal gasification and clean-up, coal fired gas turbines, and high efficiency heat engines. The objective of this research is to systematically evaluate the alkali corrosion resistance of the most commonly used structural ceramics including silicon carbide, silicon nitride, cordierite, mullite, alumina, aluminum titanate, and zirconia. The study consists of identification of the alkali reaction products and determination of the kinetics of the alkali reactions as a function of temperature and time. 145 refs., 29 figs., 12 tabs.

  10. Erosion-Corrosion of Iron and Nickel Alloys at Elevated Temperature in a Combustion Gas Environment

    Energy Technology Data Exchange (ETDEWEB)

    Tylczak, Joseph [National Energy Technology Lab. (NETL), Albany, OR (United States)

    2014-05-02

    This paper reports on the results of a study that compares the erosion-corrosion behavior of a variety of alloys (Fe- 2¼Cr 1Mo, 304 SS, 310 SS, Incoloy 800, Haynes 230 and a Fe3Al) in a combustion environment. Advanced coal combustion environments, with higher temperatures, are driving re-examination of traditional and examination of new alloys in these hostile environments. In order to simulate conditions in advanced coal combustion boilers, a special erosion apparatus was used to allow for impingement of particles under a low abrasive flux in a gaseous environment comprised of 20 % CO2, 0.05 % HCl, 77 % N2, 3 % O2, and 0.1 % SO2. Tests were conducted at room temperature and 700 °C with ~ 270 μm silica, using an impact velocity of 20 m/s in both air and the simulated combustion gas environment. The erosion-corrosion behavior was characterized by gravimetric measurements and by examination of the degraded surfaces optically and by scanning electron microscopy (SEM). At room temperature most of the alloys had similar loss rates. Not surprisingly, at 700 °C the lower chrome-iron alloy had a very high loss rate. The nickel alloys tended to have higher loss rates than the high chrome austenitic alloys.

  11. The development of an adsorbent for corrosion products in high-temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Ik; Sung, Ki Woung; Kim, Kwang Rag; Kim, Yu Hwan; Koo, Jae Hyoo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-08-01

    In order to use as adsorbent for removal of the soluble corrosion products, mainly Co{sup 60} under PWR reactor coolant conditions (300 deg C, 160 kg/cm{sup 2}), stable ZrO{sub 2} adsorbent was prepared using sol-gel process from zirconyl nitrate, AlO adsorbent was prepared by hydrolysis of aluminum isopropoxide, and titanium tetraisopropoxide, respectively. The prepared adsorbents were calcined at various temperature and analyzed by physical properties and the Co{sup 2+} adsorption capacity. And it was shown that the Co{sup 2+} adsorption capacity of the TiO{sub 2}-Al{sub 2}O{sub 3} adsorbents were found to have larger than that of ZrO{sub 2} and Al{sub 2}O{sub 3} adsorbents in high-temperature water. ZrO{sub 2}, Al{sub 2}O{sub 3} and TiO{sub 2}-Al{sub 2}O{sub 3} adsorbents were found to be suitable high-temperature adsorbents for the removal of dissolved corrosion products, mainly Co in PWR reactor coolant conditions. 15 tabs., 51 figs., 55 refs. (Author).

  12. Selected durability studies of geopolymer concrete with respect to carbonation, elevated temperature, and microbial induced corrosion

    Science.gov (United States)

    Badar, Mohammad Sufian

    This thesis reports a comprehensive study related to the experimental evaluation of carbonation in reinforced geopolymer concrete, the evaluation of geopolymer concretes at elevated temperature, and the resistance of geopolymer concrete to microbial induced corrosion (MIC). Carbonation: Reinforced concretes, made of geopolymer, prepared from two class F fly ashes and one class C fly ash, were subjected to accelerated carbonation treatment for a period of 450 days. Electrochemical, microstructure and pore structure examinations were performed to evaluate the effect of corrosion caused due to carbonation. GPC specimens prepared from class F fly ash exhibited lower corrosion rates by a factor of 21, and higher pH values (pH>12) when compared with concrete specimens prepared from class C Fly ash (GPCMN). Microstructure and pore characterization of GPC prepared using class F fly ash revealed lower porosity by a factor of 2.5 as compared with thier counterparts made using GPC-MN. The superior performace of GPC prepared with the class F fly ash could be attributed to the dense pore structure and formation of the protective layer of calcium and sodium alumino silicate hydrates (C/N-A-S-H) geopolymeric gels around the steel reinforcement. Elevated Temperature: Geopolymers are an emerging class of cementitious binders which possess a potential for high temperature resistance that could possibly be utilized in applications such as nozzles, aspirators and refractory linings. This study reports on the results of an investigation into the performance of a fly ash based geopolymer binder in high temperature environments. Geopolymer concrete (GPC) was prepared using eleven types of fly ashes obtained from four countries. High content alumina and silica sand was used in the mix for preparing GPC. GPC was subjected to thermal shock tests following ASTM C 1100-88. The GPC samples prepared with tabular alumina were kept at 1093° C and immediately quenched in water. GPC specimens

  13. Surface properties of magnetite in high temperature aqueous electrolyte solutions: A review.

    Science.gov (United States)

    Vidojkovic, Sonja M; Rakin, Marko P

    2017-07-01

    Deposits and scales formed on heat transfer surfaces in power plant water/steam circuits have a significant negative impact on plant reliability, availability and performance, causing tremendous economic consequences and subsequent increases in electricity cost. Consequently, the improvement of the understanding of deposition mechanisms on power generating surfaces is defined as a high priority in the power industry. The deposits consist principally of iron oxides, which are steel corrosion products and usually present in colloidal form. Magnetite (Fe3O4) is the predominant and most abundant compound found in water/steam cycles of all types of power plants. The crucial factor that governs the deposition process and influences the deposition rate of magnetite is the electrostatic interaction between the metal wall surfaces and the suspended colloidal particles. However, there is scarcity of data on magnetite surface properties at elevated temperatures due to difficulties in their experimental measurement. In this paper a generalized overview of existing experimental data on surface characteristics of magnetite at high temperatures is presented with particular emphasis on possible application in the power industry. A thorough analysis of experimental techniques, mathematical models and results has been performed and directions for future investigations have been considered. The state-of-the-art assessment showed that for the characterization of magnetite/aqueous electrolyte solution interface at high temperatures acid-base potentiometric titrations and electrophoresis were the most beneficial and dependable techniques which yielded results up to 290 and 200°C, respectively. Mass titrations provided data on magnetite surface charge up to 320°C, however, this technique is highly sensitive to the minor concentrations of impurities present on the surface of particle. Generally, fairly good correlation between the isoelectric point (pHiep) and point of zero charge (p

  14. Effects of sintering temperature on the corrosion behavior of AZ31 alloy with Ca–P sol–gel coating

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Bo [School of Materials Science and Engineering, Liaoning University of Technology, Jinzhou, Liaoning Province, 121001 (China); Shi, Ping, E-mail: p_shi@sohu.com [School of Materials Science and Engineering, Liaoning University of Technology, Jinzhou, Liaoning Province, 121001 (China); Wei, Donghua [School of Materials Science and Engineering, Liaoning University of Technology, Jinzhou, Liaoning Province, 121001 (China); E, Shanshan [School of Mathematics and Physics, Bohai University, Jinzhou, Liaoning Province, 121013 (China); Li, Qiang; Chen, Yang [School of Materials Science and Engineering, Liaoning University of Technology, Jinzhou, Liaoning Province, 121001 (China)

    2016-04-25

    To slow down the initial biodegradation rate of magnesium alloy, calcium phosphate (Ca–P) coatings were prepared on AZ31 magnesium alloy by a sol–gel technique. To study the effects of sintering temperature on microstructure, bonding strength and corrosion behavior of the coatings, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and an adhesive strength test were used to characterize the coatings. The corrosion resistance of the coatings was investigated by immersion test and electrochemical corrosion techniques in simulated body fluid (SBF) solution. It shows that the sol–gel coatings consist of Ca{sub 2}P{sub 2}O{sub 7}, mixture of Ca{sub 2}P{sub 2}O{sub 7}, Ca{sub 3}(PO{sub 4}){sub 2} and hydroxyapatite, and hydroxyapatite, by sintering respectively at 300 °C, 400 °C and 500 °C. There are major cracks on the coatings. The crack area portion on the coating and the bonding strength at the interface between the calcium phosphate coating and the bare AZ31 increases, and the corrosion resistance of the coated AZ31 in SBF decreases with increasing sintering temperatures from 300 °C to 500 °C. Based on our investigations, the corrosion resistance of the coated AZ31 in SBF depends mainly on the crack area portion on the coatings, rather than on the coating phase stability. - Highlights: • Ca–P coating was prepared on AZ31 alloy by a sol–gel technique. • Crack area portion in the coating increases with temperatures. • Bonding strength between Ca–P coating and substrate increases with temperatures. • Corrosion resistance of the coated AZ31 in SBF decreases with temperatures. • Corrosion resistance of the coated AZ31 depends mainly on the crack area portion.

  15. Corrosion studies of UNS N08031 in a heavy brine LiBr solution at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Garcia, D.M.; Blasco-Tamarit, E.; Igual-Munoz, A.; Garcia-Anton, J. [Valencia Univ. Politecnica, Dept. de Ingenieria Quimica y Nuclear. ETSI Industriales, Valencia (Spain)

    2009-07-01

    Lithium Bromide heavy brine solutions are used as absorbent in LiBr absorption machines. These machines are an alternative to refrigeration compression systems. The double effect absorption machines are more efficient than those of single effect, but they reach higher temperatures and they use higher LiBr concentrations. These conditions aggravate the corrosion problems on the metallic components of these systems. Therefore, it is necessary to study the corrosion resistance of the construction materials of the LiBr absorption machines, like UNS N08031, under these aggressive conditions. The objective of the present work is to study the pitting corrosion resistance and the re-passivation behaviour of a highly alloyed austenitic stainless steel (N08031) in a 1080 g/l heavy brine LiBr solution at 75 C, 100 C, 125 C and 150 C. Open Circuit Potential tests and Potentiodynamic Cyclic curves were carried out to obtain information about the electrochemical behaviour of UNS N08031 alloy. Corrosion potentials and corrosion current densities were obtained from the Tafel Analysis. The pitting corrosion resistance was evaluated from the passivation current density and the pitting potential values. The re-passivation potential and the re-passivation current density provided information about the re-passivation behaviour of UNS N08031. The samples were etched to study the microstructure by Scanning Electron Microscopy (SEM). The results showed that the potentiodynamic curves were typical of a passive material at all temperatures. Pitting corrosion resistance decreased with temperature, as the decrease in pitting potential and the increase in passivation current density evidenced. However, the re-passivation capability increased with temperature, since the width of the hysteresis loop diminished as temperature increased. (authors)

  16. High temperature corrosion of nickel-base alloys in environments containing alkali sulphate

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, Rachel; Flyg, Jesper; Caddeo, Sophie [Corrosion and Metals Research Institute, KIMAB, Stockholm (Sweden); Karlsson, Fredrik [Siemens Industrial Turbomachinery, Finspong (Sweden)

    2007-02-15

    This work is directed towards producing data to assist in lifetime assessment of components in gas turbines run in severely polluted industrial environments where the main corrosive species is SO{sub 2}, which can condense to form alkali sulphates. Corrosion rates have been measured for the base materials, in order to assess the worst-case scenario, in which cracks or other damage has occurred to the protective coating. The information is expected to be of value to manufacturers, owners and inspectors of gas turbines. Six nickel-base superalloys were subject to thermal cycles of 160 hours duration, and 0.8mg/cm{sup 2} of 20 mol % Na{sub 2}SO{sub 4} + 80mol% K{sub 2}SO{sub 4} was applied before each cycle. The test temperatures were 850 deg C and 900 deg C, with maximum test durations of 24 cycles and 12 cycles respectively. The metal loss was assessed by metallography of cross sections and the sulphidation attack was found to be very uneven. Mass change data indicated that the corrosion process was largely linear in character, and probability plots and estimations of the propagation rate of corrosion based on the linear growth assumption were produced. The performance of the alloys increased with increasing chromium content. The single crystal materials CMSX4 and MD2 showed such high corrosion rates that their use in severely contaminated industrial environments is considered inadvisable. The best performance was shown by Inconel 939 and Inconel 6203, so that even if cracks occur in the protective coating, a reasonable remaining lifetime can be expected for these materials. Sulphide formation occurred at the reaction front in all cases and mixed sulphides such as Ta-Ni or Ti-Nb sulphides were often present. The work has news value since very little long-term data is currently available for materials performance in severely sulphidising environments. The project goals in terms of exposures and metrology have been fully realised. Contributions have been made to the

  17. Corrosion of metals by hydrazine

    Science.gov (United States)

    Lawton, E. A.; Moran, C. M.; Distefano, S.

    1985-01-01

    The mechanism of corrosion of metals by hydrazine has been studied by means of coupons in sealed ampoules and by electrochemical techniques. The variables considered were temperature, CO2 impurity level, alloy composition and microcrystalline structure. The coupon studies, to date, verify that increasng temperature and the presence of CO2 does increase the corrosion rate as expected. The presence of molybdenum in stainless steels to the 3 percent level is not necessarily deleterious, contrary to published reports. The influence of microcrystalline structure and surface characteristics are more dominant effects. However, with Ti-6Al-4V, two different microcrystalline structures showed no significant differences. Corrosion rates of CRES 304 L in hydrazine have also been measured by several electrochemical techniques such as Tafel plots, polarization resistance and A. C. Impedance. This is the first documented work to show that A. C. Impedance can be used with non-aqueous solvents. Preliminary data correlated satisfactorily with the results of the coupon studies.

  18. 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.

  19. High-temperature corrosion and applications of nickel and iron aluminides in coal-conversion power systems

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K. [Argonne National Lab., IL (United States); Tortorelli, P.F. [Oak Ridge National Lab., TN (United States)

    1996-10-01

    Nickel and iron aluminide intermetallics are being developed for use as structural materials and/or as cladding for conventional engineering alloys. In addition to strength advantages, these materials exhibit excellent resistance to corrosion in single- and multioxidant environments at elevated temperatures by the formation of slow-growing, adherent alumina scales. Corrosion resistance in a given environment is strongly dependent on the composition of the alloy and on the nature of the corrosive species prevalent in the service environment. This paper presents a comprehensive review of the current status of the corrosion performance of these intermetallics in oxidizing, sulfidizing, and multicomponent gas environments of typical coal-conversion systems. Mechanisms of scale development/breakdown, performance envelopes for long-term usage of these materials, approaches to modifying the surfaces of engineering alloys by cladding or coating them with intermetallics, and in-service experience with these materials are emphasized.

  20. Oxidation/Corrosion Behaviour of ODS Ferritic/Martensitic Steels in Pb Melt at Elevated Temperature

    Directory of Open Access Journals (Sweden)

    O. I. Yaskiv

    2014-01-01

    Full Text Available Lead-based melts (Pb, Pb-Bi are considered as candidate coolants and spallation neutron targets due to their excellent thermophysical and nuclear properties. However, the corrosion of structural materials remains a major issue. Oxide dispersion strengthened (ODS ferritic/martensitic steels are considered for high temperature application for both fission and fusion reactor concepts. The oxidation/corrosion kinetics in a static oxygen-saturated Pb melt at temperature of 550°C as well as the morphology and composition of scales formed on ferritic/martensitic Fe-9Cr-1.5W and ferritic Fe-14Cr-1.5W ODS steels have been investigated. Both materials showed homogeneous multiple, dense scales that consisted of typical combination of Fe3O4 as outer sublayer and (Fe,Cr3O4 as inner sublayer. A nonuniform growth of inner oxide sublayers into the metal matrix as well as a good adhesion to the metal substrate is observed. With the prolongation of exposure from 240 to 1000 h, observed scales grow from 35 µm to 45 µm for ODS Fe-9Cr steel and from 40 µm to 60 µm for ODS Fe-14Cr steel with the thinning rates of 0,22 and 0,31 mm/year correspondingly. The mechanism of scales formation is discussed.

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

    Directory of Open Access Journals (Sweden)

    Jiemin Li

    2014-12-01

    Full Text Available 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 resistance in H2SO4 solution. The corrosion behaviors of TiZr0.5NbCr0.5 and TiZr0.5NbCr0.5Mo alloys are more sensitive to temperature than that of TiZr0.5NbCr0.5V alloy. After immersion, the surface of TiZr0.5NbCr0.5 alloy appears some pitting holes, this may be related to the electrochemical noise and serration behavior on PP curves; localized corrosion initiates mainly on the boundaries of the BCC and Cr2Zr Laves phase for TiZr0.5NbCr0.5V alloy; while for the TiZr0.5NbCr0.5Mo alloy, the dendrites with Mo element rich region exhibit poor corrosion resistance.

  2. Corrosion of high temperature resisting alloys exposed to heavy fuel ash; Corrosion de aleaciones resistentes a altas temperaturas expuestas a ceniza de combustoleo pesado

    Energy Technology Data Exchange (ETDEWEB)

    Wong Moreno, Adriana del Carmen

    1998-03-01

    The objective of the performed research was to study the degradation process by high temperature corrosion of alloys exposed to heavy fuel oil ashes through a comparative experimental evaluation of its performance that allowed to establish the mechanisms involved in the phenomenon. The experimentation carried out involved the determination of the resistance to the corrosion of 14 alloys of different type (low and medium alloy steels, ferritic and austenitic stainless steels, nickel base alloys and a FeCrAl alloy of type ODS) exposed to high temperatures (580 Celsius degrees - 900 Celsius degrees) in 15 ash deposits with different corrosive potential, which were collected in the high temperature zone of boilers of thermoelectric power stations. The later studies to the corrosion tests consisted of the analysis by sweeping electron microscopy supported by microanalysis of the corroded probes, with the purpose of determining the effect of Na, V and S on the corrosivity of the ash deposits and the effect of the main alloying elements on the corrosion resistance of the alloys. Such effects are widely documented to support the proposed mechanisms of degradation that are occurring. The global analysis of the generated results has allowed to propose a model to explain the global mechanism of corrosion of alloys exposed to the high temperatures of ash deposits. The proposed model, complements the processed one by Wilson, widely accepted for fused vanadates, as far as on one hand, it considers the effect of the sodium sulfate presence (in addition to the vanadium compounds) in the deposits, and on the other hand, it extends it to temperatures higher than the point of fusion of constituent vanadium compounds of the deposits. Both aspects involve considering the roll that the process of diffusion of species has on the degradation and the capacity of protection of the alloy. The research performed allowed to confirm what the Wilson model had established for deposits with high

  3. 9% Cr steel high temperature oxidation. Solutions investigated for improving corrosion resistance of the steel

    Energy Technology Data Exchange (ETDEWEB)

    Evin, Harold Nicolas; Heintz, Olivier; Chevalier, Sebastien [UMR 5209 CNRS-Bourgogne Univ. (France). Lab. Interdisciplinaire Carnot de Bourgogne; Foejer, Cecilia; Jakani, Saad; Dhont, Annick; Claessens, Serge [OCAS N.V. ArcelorMittal Global R and D, Gent (Belgium)

    2010-07-01

    The improvement of high temperature oxidation resistance of low chromium content steels, such as T/P91, is of great interest in regards with their application in thermal power generating plants. Indeed, they possess good creep properties, but are facing their limits of use at temperature higher than 600 C, due to accelerated corrosion phenomena. Good knowledge of the mechanisms involved during their oxidation process is needed to prevent the degradation of the materials and to extend life time of the power plants components. Oxide layers thermally grown, on 9% Cr steels (provided by OCAS N.V), during isothermal tests between 600 C and 750 C in laboratory air under atmospheric pressure were investigated, by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The oxidation behaviour appeared very limited at 750 C, due to the presence of a breakaway, which can be linked to iron porous oxide grown over the surface of the samples. ''In situ'' X-ray Photoelectron spectroscopy (XPS) analyses were performed in air at 600 C after short exposures (between 5 min and 25 h). A complex mixture of iron oxide, Cr{sub 2}O{sub 3} and Cr (VI) species were characterized in the scales. The in-situ analyses were compared and related to XPS analyses performed on thick oxide scales formed on samples oxidized in air at 600 C for 100h. An oxidation mechanism is then proposed to understand the oxide scale growth in the temperature range 600 - 750 C. The second step of this study consists in improving the high temperature corrosion resistance of these steels without modifying their mechanical properties. Thus several solutions were investigated such as MOCVD coatings, pack cementation coatings, and tested in cycle conditions prior. (orig.)

  4. High-temperature corrosion behavior of coatings and ODS alloys based on Fe{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.; Pint, B.A.; Wright, I.G.

    1996-06-01

    Iron aluminides containing greater than about 20-25 @ % Al have oxidation/sulfidation resistance at temperatures well above those at which these alloys have adequate mechanical strength. In addition to alloying modifications for improved creep resistance of wrought material, this strength limitation is being addressed by development of oxide-dispersion- strengthened (ODS) iron aluminides and by evaluation of Fe{sub 3}Al alloy compositions as coatings or claddings on higher-strength, less corrosion-resistant materials. As part of these efforts, the high-temperature corrosion behavior of iron-aluminide weld overlays and ODS alloys is being characterized and compared to previous results for ingot-processed material.

  5. An evaluation of mechanical and high-temperature corrosion properties of Ni-Cr alloy with composition of alloying elements

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Sujin; Kim, Dongjin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Helium is used as a coolant in a VHTR owing to its high thermal conductivity, inertness, and low neutron absorption. However, helium inevitably includes impurities that create an imbalance in the surface reactivity at the interface of the coolant and the exposed materials. As the Alloy 617 has been exposed to high temperatures at 950 .deg. C in the impure helium environment of a VHTR, degradation of material is accelerated and mechanical properties decreased. An alloy superior to alloy 617 should be developed. In this study, the mechanical and high-temperature corrosion properties for Ni-Cr alloys fabricated in laboratory were evaluated as a function of the grain boundary strengthening and alloying element composition. The mechanical property and corrosion property for Ni-Cr alloys fabricated in a laboratory were evaluated as a function of the main element composition. The ductility was increased and decreased by increasing the amount of Mo and Cr, respectively. Surface oxide was detached during the corrosion test, because there was not aluminum element in the alloy. Aluminum seems to act as an anti-corrosive role in Ni-based alloy. In conclusion, the addition of Al into the alloy is required to improvement of high temperature corrosion resistance.

  6. TEM studies of high temperature corrosion behaviour of TiAl intermetallics with surface modifications

    Energy Technology Data Exchange (ETDEWEB)

    Du, H.L.; Rose, S.R.; Xiang, Z.D.; Datta, P.K. [University of Northumbria, Advanced Materials Research Institute, Ellison Building, Ellison Place, NE1 8 ST Newcastle upon Tyne (United Kingdom); Li, X.Y. [Ion Engieneering Research Institute Corporation, 2-8-1, Tsudayamate, Hirakata, Osaka 513-0128 (Japan)

    2003-04-01

    The oxidation/sulphidation behaviour of a Ti-46.7Al-1.9W-0.5Si alloy with a TiAl{sub 3} diffusion coating was studied in an environment of H{sub 2}/H{sub 2}S/H{sub 2}O at 850{sup o}C. The kinetic results demonstrate that the TiAl{sub 3} coating significantly increased the high temperature corrosion resistance of Ti-46.7Al-1.9W-0.5Si. The SEM, EDX, XRD and TEM analysis reveals that the formation of an Al{sub 2}O{sub 3} scale on the surface of the TiAl{sub 3}-coated sample was responsible for the enhancement of the corrosion resistance. The Ti-46.7Al-1.9W-0.5Si alloy was also modified by Nb ion implantation. The Nb ion implanted and as received samples were subjected to cyclic oxidation in an open air at 800{sup o}C. The Nb ion implantation not only increased the oxidation resistance but also substantially improved the adhesion of scale to the substrate. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  7. KCl-induced high temperature corrosion of selected commercial alloys. Part I: chromia-formers

    DEFF Research Database (Denmark)

    Kiamehr, Saeed; Dahl, Kristian Vinter; Montgomery, Melanie

    2015-01-01

    Laboratory testing of selected chromia-forming alloys was performed to rank the materials and gain further knowledge on the mechanism of KCl-induced high temperature corrosion. The investigated alloys were stainless steels EN1.4021, EN1.4057, EN1.4521, TP347H (coarse-grained), TP347HFG (fine......-grained), Sanicro 28 and the nickel-based alloys 625, 263 and C276. Exposure was performed at 600 °C for 168 h in flowing N2(g)+5%O2(g)+15% H2O(g) (vol.%). Samples were covered with KCl powder prior to exposure. A salt-free exposure was also performed for comparison. Corrosion morphology and products were studied...... with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). It was observed that in the salt-free exposure, stainless steels TP347H (coarse-grained) and EN1.4521 failed to form a thin protective oxide layer compared to the oxide formed on the other alloys...

  8. Osmotic potential calculations of inorganic and organic aqueous solutions over wide solute concentration levels and temperatures.

    Science.gov (United States)

    Cochrane, T T; Cochrane, T A

    2016-01-01

    To demonstrate that the authors' new "aqueous solution vs pure water" equation to calculate osmotic potential may be used to calculate the osmotic potentials of inorganic and organic aqueous solutions over wide ranges of solute concentrations and temperatures. Currently, the osmotic potentials of solutions used for medical purposes are calculated from equations based on the thermodynamics of the gas laws which are only accurate at low temperature and solute concentration levels. Some solutions used in medicine may need their osmotic potentials calculated more accurately to take into account solute concentrations and temperatures. The authors experimented with their new equation for calculating the osmotic potentials of inorganic and organic aqueous solutions up to and beyond body temperatures by adjusting three of its factors; (a) the volume property of pure water, (b) the number of "free" water molecules per unit volume of solution, "Nf," and (c) the "t" factor expressing the cooperative structural relaxation time of pure water at given temperatures. Adequate information on the volume property of pure water at different temperatures is available in the literature. However, as little information on the relative densities of inorganic and organic solutions, respectively, at varying temperatures needed to calculate Nf was available, provisional equations were formulated to approximate values. Those values together with tentative t values for different temperatures chosen from values calculated by different workers were substituted into the authors' equation to demonstrate how osmotic potentials could be estimated over temperatures up to and beyond bodily temperatures. The provisional equations formulated to calculate Nf, the number of free water molecules per unit volume of inorganic and organic solute solutions, respectively, over wide concentration ranges compared well with the calculations of Nf using recorded relative density data at 20 °C. They were

  9. The Effect of Temperature and Acid Concentration on Corrosion of Low Carbon Steel in Hydrochloric Acid Media

    OpenAIRE

    Anees A. Khadom; Aprael S. Yaro; Abdul A.H. Kadum; Ahmed S. AlTaie; Ahmed Y. Musa

    2009-01-01

    Problem statement: The effect of different temperatures and acid concentrations on the corrosion of low carbon steel in hydrochloric acid were addressed in this study. Approach: The effect of temperature was explained by application of Arrhenius equation and transition state theory, while the acid concentration effect was explained using reaction kinetic equations. The combined effect of temperature and acid concentration then modeled using a nonlinear regression method. Results: A detail of ...

  10. Corrosion in supercritical fluids

    Energy Technology Data Exchange (ETDEWEB)

    Propp, W.A.; Carleson, T.E.; Wai, Chen M.; Taylor, P.R.; Daehling, K.W.; Huang, Shaoping; Abdel-Latif, M.

    1996-05-01

    Integrated studies were carried out in the areas of corrosion, thermodynamic modeling, and electrochemistry under pressure and temperature conditions appropriate for potential applications of supercritical fluid (SCF) extractive metallurgy. Carbon dioxide and water were the primary fluids studied. Modifiers were used in some tests; these consisted of 1 wt% water and 10 wt% methanol for carbon dioxide and of sulfuric acid, sodium sulfate, ammonium sulfate, and ammonium nitrate at concentrations ranging from 0.00517 to 0.010 M for the aqueous fluids. The materials studied were Types 304 and 316 (UNS S30400 and S31600) stainless steel, iron, and AISI-SAE 1080 (UNS G10800) carbon steel. The thermodynamic modeling consisted of development of a personal computer-based program for generating Pourbaix diagrams at supercritical conditions in aqueous systems. As part of the model, a general method for extrapolating entropies and related thermodynamic properties from ambient to SCF conditions was developed. The experimental work was used as a tool to evaluate the predictions of the model for these systems. The model predicted a general loss of passivation in iron-based alloys at SCF conditions that was consistent with experimentally measured corrosion rates and open circuit potentials. For carbon-dioxide-based SCFs, measured corrosion rates were low, indicating that carbon steel would be suitable for use with unmodified carbon dioxide, while Type 304 stainless steel would be suitable for use with water or methanol as modifiers.

  11. Sustainable Gel Electrolyte Containing Pyrazole as Corrosion Inhibitor and Dendrite Suppressor for Aqueous Zn/LiMn2 O4 Battery.

    Science.gov (United States)

    Hoang, Tuan K A; Doan, The Nam Long; Cho, Julie Hyeonjoo; Su, Jane Ying Jun; Lee, Christine; Lu, Changyu; Chen, P

    2017-07-10

    The Zn anode in secondary aqueous batteries suffers from dendrite formation and corrosion. In this work, dendrite formation was suppressed by using a simple but new gel electrolyte containing fumed silica and an additive. The dendrite suppression was evidenced by chronoamperometry and ex situ scanning electron microscopy examinations. Pyrazole was implemented as the additive in the electrolyte. It was found that the presence of 0.2 wt % pyrazole in the electrolyte helped minimize both corrosion and dendrite formation. The Zn/LiMn2 O4 battery using pyrazole-containing gel electrolytes exhibited high cyclability up to 85 % capacity retention after 500 charge-discharge cycles at 4C. This was 8 % higher than the performance of the reference battery (using aqueous electrolyte containing 2 m Li2 SO4 and 1 m ZnSO4 ). Furthermore, self-discharge of the battery with the pyrazole-containing gel electrolyte was suppressed, as evidenced by an open-circuit voltage loss that was 20 % lower than for the reference battery after 24 h monitoring. Float-charge current density under constant voltage (2.1 V) also significantly decreased from approximately 8.0 to 3-6 μA. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Corrosion Protection of Phenolic-Epoxy/Tetraglycidyl Metaxylediamine Composite Coatings in a Temperature-Controlled Borax Environment

    Science.gov (United States)

    Xu, Wenhua; Wang, Zhenyu; Han, En-Hou; Liu, Chunbo

    2017-12-01

    The failure behavior for two kinds of phenolic-epoxy/tetraglycidyl metaxylediamine composite coatings in 60 °C borax aqueous solution was evaluated using electrochemical methods (EIS) combined with scanning electron microscopy, confocal laser scanning microscope, water immersion test, and Raman spectrum. The main focus was on the effect of curing agent on the corrosion protection of coatings. Results revealed that the coating cured by phenolic modified aromatic amine possessed more compact cross-linked structure, better wet adhesion, lower water absorption (0.064 mg h-1 cm-2) and its impedance values was closed to 108 Ω cm2 after immersion for 576 h, while the coating cured by modified aromatic ring aliphatic amine was lower than 105 Ω cm2. The corrosion mechanism of the two coatings is discussed.

  13. High temperature degradation by erosion-corrosion in bubbling fluidized bed combustors

    Directory of Open Access Journals (Sweden)

    Hou Peggy

    2004-01-01

    Full Text Available Heat-exchanger tubes in fluidized bed combustors (FBCs often suffer material loss due to combined corrosion and erosion. Most severe damage is believed to be caused by the impact of dense packets of bed material on the lower parts of the tubes. In order to understand this phenomenon, a unique laboratory test rig at Berkeley was designed to simulate the particle hammering interactions between in-bed particles and tubes in bubbling fluidized bed combustors. In this design, a rod shaped specimen is actuated a short distance within a partially fluidized bed. The downward specimen motion is controlled to produce similar frequencies, velocities and impact forces as those experienced by the impacting particle aggregates in practical systems. Room temperature studies have shown that the degradation mechanism is a three-body abrasion process. This paper describes the characteristics of this test rig, reviews results at elevated temperatures and compares them to field experience. At higher temperatures, deposits of the bed material on tube surfaces can act as a protective layer. The deposition depended strongly on the type of bed material, the degree of tube surface oxidation and the tube and bed temperatures. With HCl present in the bed, wastage was increased due to enhanced oxidation and reduced oxide scale adherence.

  14. Application of aluminum diffusion coatings to mitigate the KCl-induced high-temperature corrosion

    DEFF Research Database (Denmark)

    Kiamehr, Saeed; Lomholt, T. N.; Dahl, Kristian Vinter

    2017-01-01

    Pack cementation was used to produce Fe1−xAl and Fe2Al5 diffusion coatings on ferritic-martensitic steel P91 and a Ni2Al3 diffusion coating on pure nickel. The performance of diffusion coatings against high-temperature corrosion induced by potassium chloride (KCl) was evaluated by exposing......-ray diffractometry (XRD) before and after the exposures. It was found that all the diffusion coatings formed protective oxides under salt-free exposure in air. Under the salt deposit, Fe1−xAl showed local failure while on large parts of the sample a protective layer had formed. Fe2Al5 was attacked over the entire...

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

    Science.gov (United States)

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

    2015-03-01

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

  16. Na2SO4 induced corrosion of nickel at high temperature

    Science.gov (United States)

    Misra, A. K.

    1985-01-01

    Sodium sulfate-induced corrosion of nickel was studied at 900 C as a function of oxygen partial pressure. For high O2 partial pressures, accelerated corrosion during the first few minutes occurred by rapid penetration of the melt along the metal grain boundaries. A mechanism is proposed to explain this phenomenon. Repetitive scale metal detachment was observed for corrosion in lower O2 partial pressures and during the later period of corrosion in higher O2 partial pressures. The effect of preoxidation on the hot corrosion has also been studied. An induction period is observed before the onset of rapid corrosion for the preoxidized samples; the onset of rapid corrosion is associated with sudden cracking of the scale. The length of the induction period for the preoxidized samples is a function of the length of preoxidation, and appears to be related to the structure of the oxide scale after the preoxidation treatment.

  17. High temperature corrosion of advanced ceramic materials for hot gas filters and heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Crossland, C.E.; Shelleman, D.L.; Spear, K.E. [Pennsylvania State Univ., University Park, PA (United States)] [and others

    1996-08-01

    A vertical flow-through furnace has been built to study the effect of corrosion on the morphology and mechanical properties of ceramic hot gas filters. Sections of 3M Type 203 and DuPont Lanxide SiC-SiC filter tubes were sealed at one end and suspended in the furnace while being subjected to a simulated coal combustion environment at 870{degrees}C. X-ray diffraction and electron microscopy is used to identify phase and morphology changes due to corrosion while burst testing determines the loss of mechanical strength after exposure to the combustion gases. Additionally, a thermodynamic database of gaseous silicon compounds is currently being established so that calculations can be made to predict important products of the reaction of the environment with the ceramics. These thermodynamic calculations provide useful information concerning the regimes where the ceramic may be degraded by material vaporization. To verify the durability and predict lifetime performance of ceramic heat exchangers in coal combustion environments, long-term exposure testing of stressed (internally pressurized) tubes must be performed in actual coal combustion environments. The authors have designed a system that will internally pressurize 2 inch OD by 48 inch long ceramic heat exchanger tubes to a maximum pressure of 200 psi while exposing the outer surface of the tubes to coal combustion gas at the Combustion and Environmental Research Facility (CERF) at the Pittsburgh Energy and Technology Center. Water-cooled, internal o-ring pressure seals were designed to accommodate the existing 6 inch by 6 inch access panels of the CERF. Tubes will be exposed for up to a maximum of 500 hours at temperatures of 2500 and 2600{degrees}F with an internal pressure of 200 psi. If the tubes survive, their retained strength will be measured using the high temperature tube burst test facility at Penn State University. Fractographic analysis will be performed to identify the failure source(s) for the tubes.

  18. Corrosion behaviour of an AlZnSnSrGa alloy in aqueous solutions of NaCl and Na2SO4

    Directory of Open Access Journals (Sweden)

    S. MENTUS

    2000-01-01

    Full Text Available 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 range 0.00051- 0.51 mol dm-3. Over the whole salt concentration ranges, the corrosion parameters indicate that the corrosion rate of the alloy is significantly higher than the rate of the base material. For instance, for the concentration range 0.00051- 0.51 mol dm-3, the stationary open circuit potentials, related to SCE, in NaCl solutions were -1.200 to -1.460 V for the alloy and - 0.693 to - 0.920 V for Al, while in Na2SO4 solutions, the stationary open circuit potentials were - 1.190 to - 1.465 V for the alloy and - 0.780 to - 0.860 V for Al. At the same time, the corrosion current density in NaCl solutions varied within 11- 89 mA cm-2 for the alloy and 0.35- 0.80 for Al, while in Na2SO4 solutions it amounted to 5.7-52 mA cm-2 for the alloy and 0.28 - 0.88 mA cm-2 for Al.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-07-01

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

  20. High temperature corrosion in gas turbines: fuel model and experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Bordenet, B.; Bossmann, H.P. [ALSTOM (Schweiz) AG, Baden (Switzerland)

    2002-07-01

    The corrosion in gas turbines is caused by the interaction of the combustion gas and the materials. The risk of sulfate-induced hot corrosion arises if impurities of fuel, air and water can form corrosive compounds and condense on the materials. The compositions and the dewpoints of such deposits depend on the pressure and on the amount of impurities, e. g. Na, K, S. Thermodynamical modelling of the dewpoints was performed to determine the zones in the gas turbine with a risk of hot corrosion. Beside the theoretical approach, corrosion experiments were done with blading materials and protective coatings. The hot corrosion behaviour of three base materials, IN738 trademark, CM247 trademark and CMSX-4 trademark, and SV20, a NiCrAlY-coating material, was studied in a salt-spraying test. For each material, specimens coated with Na{sub 2}SO{sub 4} and Na{sub 2}SO{sub 4}/K{sub 2}SO{sub 4} were exposed between 750 and 950 C in air with 300 ppm SO{sub 2}. The present investigation has established that the addition of K{sub 2}SO{sub 4} to Na{sub 2}SO{sub 4} causes shorter incubation periods and higher corrosion rates. IN738 has shown a good resistance against hot corrosion. The corrosion resistance of CM247 and CMSX-4 was very poor. In a corrosive environment, both alloys have to be protected by an oxidation- and corrosion-resistant coating. SV20 has exhibited an excellent corrosion resistance with incubation times >1000 h at 800 C. The present study has shown that the combination of thermodynamical modelling and corrosion experiments is a suitable approach to assess the risk of hot corrosion in gas turbines. (orig.)

  1. High temperature corrosion of advanced ceramic materials for hot gas filters. Topical report for part 1 of high temperature corrosion of advanced ceramic materials for hot gas filters and heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Spear, K.E.; Crossland, C.E.; Shelleman, D.L.; Tressler, R.E. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering

    1997-12-11

    This program consists of two separate research areas. Part 1, for which this report is written, studied the high temperature corrosion of advanced ceramic hot gas filters, while Part 2 studied the long-term durability of ceramic heat exchangers to coal combustion environments. The objectives of Part 1 were to select two candidate ceramic filter materials for flow-through hot corrosion studies and subsequent corrosion and mechanical properties characterization. In addition, a thermodynamic database was developed so that thermochemical modeling studies could be performed to simulate operating conditions of laboratory reactors and existing coal combustion power plants, and to predict the reactions of new filter materials with coal combustion environments. The latter would make it possible to gain insight into problems that could develop during actual operation of filters in coal combustion power plants so that potential problems could be addressed before they arise.

  2. Effect of Annealing Temperature on the Corrosion Protection of Hot Swaged Ti-54M Alloy in 2 M HCl Pickling Solutions

    Directory of Open Access Journals (Sweden)

    El-Sayed M. Sherif

    2017-01-01

    Full Text Available The corrosion of Ti-54M titanium alloy processed by hot rotary swaging and post-annealed to yield different grain sizes, in 2 M HCl solutions is reported. Two annealing temperatures of 800 °C and 940 °C, followed by air cooling and furnace cooling were used to give homogeneous grain structures of 1.5 and 5 μm, respectively. It has been found that annealing the alloy at 800 °C decreased the corrosion of the alloy, with respect to the hot swaged condition, through increasing its corrosion resistance and decreasing the corrosion current and corrosion rate. Increasing the annealing temperature to 940 °C further decreased the corrosion of the alloy.

  3. The stress corrosion resistance and the cryogenic temperature mechanical properties of hot rolled Nitronic 32 bar material

    Science.gov (United States)

    Montano, J. W. L.

    1977-01-01

    The ambient and cryogenic temperature mechanical properties and the ambient temperature stress corrosion properties of hot rolled and centerless ground Nitronic 32 stainless steel bar material are presented. The mechanical properties of longitudinal specimens were evaluated at test temperatures from ambient to liquid hydrogen. The tensile test data indicated increasing smooth tensile strength with decreasing temperature to liquid hydrogen temperature. However, below -200 F (-129.0 C) the notched tensile strength decreased slightly and below -320 F (-196.0 C) the decrease was significant. The elongation and reduction of area decreased drastically at temperatures below -200 F (-129.0 C). The Charpy V-notched impact energy decreased steadily with decreasing test temperature. Stress corrosion tests were performed on longitudinal tensile specimens stressed to 0, 75, and 90 percent of the 0.2 percent yield strength and on transverse 'C'-ring specimens stressed to 75 and 90 percent of the yield strength and exposed to: alternate immersion in a 3.5 percent NaCl bath, humidity cabinet environment, and a 5 percent salt spray atmosphere. The longitudinal tensile specimens experienced no corrosive attack; however, the 'C'-rings exposed to the alternate immersion and to the salt spray experienced some shallow etching and pitting, respectively. Small cracks appeared in two of the 'C'-rings after one month exposure to the salt spray.

  4. Effect of temperature and salting-out agents on the sorption of nitrophenols from aqueous solutions

    Directory of Open Access Journals (Sweden)

    E. V. Churilina

    2013-01-01

    Full Text Available Sorption of nitrophenols from aqueous media by сrosslinked N-vinylpyrrolidone-based polymer in static conditions are studied depending on the pH of the solution and the nature of the nitrophenols. It has been established that a temperature and the introduction of salting-out agents influence on the sorption of nitrophenols.

  5. Aqueous synthesis of porous platinum nanotubes at room temperature and their intrinsic peroxidase-like activity.

    Science.gov (United States)

    Cai, Kai; Lv, Zhicheng; Chen, Kun; Huang, Liang; Wang, Jing; Shao, Feng; Wang, Yanjun; Han, Heyou

    2013-07-11

    Platinum nanotubes (PtNTs) exhibiting high porosity were constructed by sacrificing the exterior of tellurium nanowires (TeNWs) and disintegrating the inner part spontaneously in aqueous solution at room temperature, in which the Kirkendall effect may play an important role. The present PtNTs exhibited intrinsic peroxidase-like activity in the presence of H2O2.

  6. Investigation of the Effects of Solution Temperature on the Corrosion Behavior of Austenitic Low-Nickel Stainless Steels in Citric Acid using Impedance and Polarization Measurements

    Directory of Open Access Journals (Sweden)

    Mulimbayan Francis M.

    2015-01-01

    Full Text Available Stainless steels may be classified according to alloy microstructure – ferritic, austenitic, martensitic, duplex, and precipitation hardening grades. Among these, austenitic grade has the largest contribution to market due to the alloy’s numerous industrial and domestic applications. In this study, the corrosion behavior of low-Nickel stainless steel in citric acid was investigated using potentiodynamic polarization techniques and Electrochemical Impedance Spectroscopy (EIS. The corrosion current density which is directly related to corrosion rate was extracted from the generated anodic polarization curve. Increasing the temperature of the citric acid resulted to increased corrosion current densities indicating higher corrosion rates at initial corrosion condition. EIS was performed to generate Nyquist plots whose shape and size depicts the corrosion mechanism and corrosion resistance of the alloy in citric acid, respectively. All the generated Nyquist plots have depressed semi-circle shapes implying that corrosion process takes place with charge-transfer as the rate-determining step. Based from the extracted values of polarization resistance (Rp, the temperature of the solution has negative correlation with the corrosion resistance of the studied alloy.

  7. Corrosion behavior of shape memory, superelastic, and nonsuperelastic nickel-titanium-based orthodontic wires at various temperatures.

    Science.gov (United States)

    Pun, Deo K; Berzins, David W

    2008-02-01

    Nickel-titanium orthodontic wires have various temperature-dependent phases. The purpose of this study was to investigate temperature-dependent corrosion characteristics of shape memory, superelastic, and nonsuperelastic orthodontic wires. Four orthodontic wires were investigated: 27 and 40 degrees C copper Ni-Ti (superelastic and shape memory, respectively), superelastic Ni-Ti, and nonsuperelastic Nitinol Classic. Differential scanning calorimetry (DSC) was used to confirm phase/temperature behavior of the wires. Sectioned halves of as-received archwires were assessed electrochemically in artificial saliva at 5, 24, 37, and 45 degrees C. Open circuit potential (OCP) was monitored for 2h followed by polarization resistance and cyclic polarization tests. DSC results showed Nitinol was primarily martensitic-stable whereas NiTi, 27 degrees C CuNiTi, and 40 degrees C CuNiTi possessed austenite-finish temperatures of approximately 19, 21, and 38 degrees C. The OCP of the CuNiTi wires was significantly greater than NiTi and Nitinol but no apparent trend in values was apparent with regard to temperature or phases present. Corrosion current density (i(corr)) increased with temperature for all wires, but not all were equally influenced. The two lowest austenite-finish temperature wires (27 degrees C CuNiTi and NiTi) approximately tripled in i(corr) from 37 to 45 degrees C. Greater incidence of pitting was observed in the CuNiTi wires. This study showed the corrosion rate of various nickel-titanium wires increase with temperature and different phases present may influence corrosion rate trends.

  8. KCl-Induced High-Temperature Corrosion Behavior of HVAF-Sprayed Ni-Based Coatings in Ambient Air

    Science.gov (United States)

    Jafari, Reza; Sadeghimeresht, Esmaeil; Farahani, Taghi Shahrabi; Huhtakangas, Matti; Markocsan, Nicolaie; Joshi, Shrikant

    2018-01-01

    KCl-induced high-temperature corrosion behavior of four HVAF-sprayed Ni-based coatings (Ni21Cr, Ni5Al, Ni21Cr7Al1Y and Ni21Cr9Mo) under KCl deposit has been investigated in ambient air at 600 °C up to 168 h. The coatings were deposited onto 16Mo3 steel—a widely used boiler tube material. Uncoated substrate, 304L and Sanicro 25 were used as reference materials in the test environment. SEM/EDS and XRD techniques were utilized to characterize the as-sprayed and exposed samples. The results showed that the small addition of KCl significantly accelerated degradation to the coatings. All coatings provided better corrosion resistance compared to the reference materials. The alumina-forming Ni5Al coating under KCl deposit was capable of forming a more protective oxide scale compared to the chromia-forming coatings as penetration of Cl through diffusion paths was hindered. Both active corrosion and chromate formation mechanisms were found to be responsible for the corrosion damages. The corrosion resistance of the coatings based on the microstructure analysis and kinetics had the following ranking (from the best to worst): Ni5Al > Ni21Cr > Ni21Cr7Al1Y > Ni21Cr9Mo.

  9. The effect of heat treatment and test parameters on the aqueous stress corrosion cracking of D6AC steel

    Science.gov (United States)

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

    1974-01-01

    The crack growth behavior of D6AC steel as a function of stress intensity, stress and corrosion history and test technique, under sustained load in natural seawater, 3.3 percent NaCl solution, distilled water, and high humidity air was investigated. Reported investigations of D6AC were considered with emphasis on thermal treatment, specimen configuration, fracture toughness, crack-growth rates, initiation period, threshold, and the extension of corrosion fatigue data to sustained load conditions. Stress history effects were found to be most important in that they controlled incubation period, initial crack growth rates, and apparent threshold.

  10. Corrosion of low Si-alloyed steels in aqueous solution at 90 deg. C. Inhibitive action of silicates; Corrosion d'aciers faiblement allies au silicium en solution aqueuse a 90 deg. C. Action inhibitrice des silicates

    Energy Technology Data Exchange (ETDEWEB)

    Giordana, S

    2002-02-01

    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)

  11. Monitoring corrosion and corrosion control of iron in HCl by non-ionic surfactants of the TRITON-X series - Part II. Temperature effect, activation energies and thermodynamics of adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Amin, Mohammed A., E-mail: maaismail@yahoo.co [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia); Department of Chemistry, Faculty of Science, Ain shams University, 11566 Abbassia, Cairo (Egypt); Ahmed, M.A. [Physics Department, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia); Arida, H.A. [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia); Arslan, Taner [Department of Chemistry, Eskisehir Osmangazi University, 26480 Eskisehir (Turkey); Saracoglu, Murat [Faculty of Education, Erciyes University, 38039 Kayseri (Turkey); Kandemirli, Fatma [Department of Chemistry, Nigde University, 41000 Nigde (Turkey)

    2011-02-15

    Research highlights: TX-305 exhibits inhibiting properties for iron corrosion more than TX-165 and TX 100. Inhibition efficiency increases with temperature, suggesting chemical adsorption. The three tested surfactants act as mixed-type inhibitors with cathodic predominance. Validation of corrosion rates measured by Tafel extrapolation method is confirmed. - Abstract: The inhibition characteristics of non-ionic surfactants of the TRITON-X series, namely TRITON-X-100 (TX-100), TRITON-X-165 (TX-165) and TRITON-X-305 (TX-305), on the corrosion of iron was studied in 1.0 M HCl solutions as a function of inhibitor concentration (0.005-0.075 g L{sup -1}) and solution temperature (278-338 K). Measurements were conducted based on Tafel extrapolation method. Electrochemical frequency modulation (EFM), a non-destructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, is also presented. Experimental corrosion rates determined by the Tafel extrapolation method were compared with corrosion rates obtained by the EFM technique and an independent method of chemical analysis. The chemical method of confirmation of the corrosion rates involved determination of the dissolved cation, using ICP-AES (inductively coupled plasma atomic emission spectrometry). The aim was to confirm validation of corrosion rates measured by the Tafel extrapolation method. Results obtained showed that, in all cases, the inhibition efficiency increased with increase in temperature, suggesting that chemical adsorption occurs. The adsorptive behaviour of the three surfactants followed Temkin-type isotherm. The standard free energies of adsorption decreased with temperature, reflecting better inhibition performance. These findings confirm chemisorption of the tested inhibitors. Thermodynamic activation functions of the dissolution process were also calculated as a function of each inhibitor concentration. All the results obtained from

  12. Oxygen sensor development and low temperature corrosion study in lead-alloy coolant loop

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Il Soon; Bahn, Chi Bum; Lee, Seung Gi; Jeong, Seung Ho; Nam, Hyo On; Lim, Jun [Seoul National University, Seoul (Korea, Republic of)

    2007-07-15

    Oxygen sensor to measure dissolved oxygen concentration at liquid lead-bismuth eutectic environments have been developed. Developed oxygen sensor for application in lead-bismuth eutectic (LBE) system was based on the oxygen ion conductor made of YSZ ceramic having Bi/Bi2O3 reference joined by electro-magnetic swaging. Leakage problem, which was major problem of existing sensors, can be solved by using electro-magnetic swaging method. A new calibration strategy combining the oxygen titration with electrochemical impedance spectroscopy (EIS) was performed to increase the reliability of sensor. Another calibration was also conducted by controlling the oxygen concentration using OCS (oxygen control system). Materials corrosion tests of various metals (SS316, EP823, T91 and HT9) were conducted for up to 1,000 hours with specimen inspection after every 333hours at 450 .deg. C in HELIOS. Oxygen concentration was controlled at 10{sup -6} wt% by using the direct gas bubbling of Ar+4%H{sub 2}, Ar+5%O{sub 2} and pure Ar. The dissolved oxygen concentration in LBE was also monitored by two calibrated YSZ oxygen sensors located at different places under different temperatures within HELIOS. It shows a good performance during 1000 hours. Liquid metal embrittlement (LME) test of SS316L specimen in the LBE was performed at various temperature and strain rate. The result shows that the liquid metal embrittlement effect is not crucial at tested conditions.

  13. Temperature, stress, and corrosive sensing apparatus utilizing harmonic response of magnetically soft sensor element (s)

    Science.gov (United States)

    Grimes, Craig A. (Inventor); Ong, Keat Ghee (Inventor)

    2003-01-01

    A temperature sensing apparatus including a sensor element made of a magnetically soft material operatively arranged within a first and second time-varying interrogation magnetic field, the first time-varying magnetic field being generated at a frequency higher than that for the second magnetic field. A receiver, remote from the sensor element, is engaged to measure intensity of electromagnetic emissions from the sensor element to identify a relative maximum amplitude value for each of a plurality of higher-order harmonic frequency amplitudes so measured. A unit then determines a value for temperature (or other parameter of interst) using the relative maximum harmonic amplitude values identified. In other aspects of the invention, the focus is on an apparatus and technique for determining a value for of stress condition of a solid analyte and for determining a value for corrosion, using the relative maximum harmonic amplitude values identified. A magnetically hard element supporting a biasing field adjacent the magnetically soft sensor element can be included.

  14. Effect of dissolved hydrogen on corrosion of 316NG stainless steel in high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Lijin [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang City 110819 (China); Peng, Qunjia, E-mail: qunjiapeng@imr.ac.cn [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Zhang, Zhiming [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Shoji, Tetsuo [Frontier Research Initiative, New Industry Creation Hatchery Center, Tohoku University, 6-6-10, Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Han, En-Hou; Ke, Wei [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Wang, Lei [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang City 110819 (China)

    2015-12-15

    Highlights: • Dissolved hydrogen (DH) effect on corrosion of stainless steel in high temperature water. • Increasing DH caused decrease of Cr- but increase of Fe-concentrations in the inner oxide layer. • Concentration gradient of Cr and Fe in the inner oxide layer. • DH effect was attributed to the accelerated diffusion of Fe ion in the inner oxide layer. - Abstract: Characterizations of oxide films formed on 316 stainless steel in high temperature, hydrogenated water were conducted. The results show the oxide film consists of an outer layer with oxide particles of Fe–Ni spinel and hematite, and an inner continuous layer of Fe–Cr–Ni spinel. Increasing dissolved hydrogen (DH) concentrations causes decrease of Cr- and increase of Fe-concentrations in the inner layer. A continuous decrease of Cr- and increase of Fe-concentrations was observed from the surface of the inner layer to the oxide/substrate interface. The DH effect is attributed to the enhanced diffusion of Fe ions in the oxide film by hydrogen.

  15. Detection and evaluation of corrosion zones at high temperature in steam generators; Deteccion y evaluacion de zonas de corrosion en alta temperatura de generadoras de vapor

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Villafane, Alberto; Chacon Nava, Jose G.; Huerta Espino, Mario; Mojica Calderon, Cecilio; Castillo Viveros, Antonio [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1990-12-31

    This paper presents the methodology for the detection and evaluation of high corrosion zones at high temperature. The results found up to now, show a critical zone in the Babcock Hitachi design, specifically in the high temperature reheater in the zone nearby the outlet header. In the normalized design CE (Mitsubishi) of 300 MW and CE (Canada) of 300 MW, the results found in recent years show small thickness reduction, therefore a good operation of these steam generators is recognized. [Espanol] En este trabajo se presenta la metodologia para la deteccion y evaluacion de zonas de corrosion en alta temperatura. Los resultados encontrados hasta el momento muestran una zona critica en el diseno Babcock Hitachi, especificamente en el recalentador de alta temperatura en la zona cercana al cabezal de salida. En el diseno normalizado CE (Mitsubishi) de 300 MW y CE (Canada) de 300 MW, los resultados encontrados en anos recientes muestran poca disminucion de espesor, por lo que se considera una buena operacion de estos generadores de vapor.

  16. MULTISYS: Computer code for calculating multicomponent equilibria in high-temperature subcritical and supercritical aqueous systems; MULTISYS: Ein Programm zur Berechnung von Mehrkomponenten-Gleichgewichten in unterkritischen und ueberkritischen waessrigen Systemen

    Energy Technology Data Exchange (ETDEWEB)

    Lvov, S.N.; Akinfiev, N.N.; Bandura, A.V.; Sigon, F.; Perboni, G.

    1999-12-01

    The studies of the corrosion and deposition processes on the structural materials of power plants in high temperature aqueous environments have aroused considerable interest. To understand these processes, it is required to develop a detailed knowledge of thermodynamics that control the solution chemistry, phase relations, kinetics, and mass and heat transport. By knowing the equilibrium composition of the high temperature aqueous solution and by accessing the thermodynamic properties of the corrosion products, it is possible to predict the initial stage of the corrosion processes or oxides deposition, in order to protect plant equipment against damages. (orig.) [German] Studien zur Korrosion und zu Ablagerungsprozessen auf den Komponentenwerkstoffen in Kraftwerken in einer waessrigen Hochtemperaturumgebung sind von betraechtlichem Interesse. Um solche Prozesse zu verstehen, muss ein detailliertes Verstaendnis der Thermodynamik vorhanden sein, welches die Loesungschemie, Phasenbeziehungen, Kinetik sowie Masse- und Waermetransport kontrolliert. Mit dem Wissen um die Gleichgewichtszusammensetzung der waessrigen Hochtemperaturloesung und unter Zugriff auf die thermodynamischen Eigenschaften der Korrosionsprodukte ist es moeglich, die einleitende Stufe von Korrosionsprozessen oder Oxidablagerungen vorherzusagen, um so Anlagenkomponenten vor Schaeden zu schuetzen. (orig.)

  17. Effect of Annealing Temperature on the Mechanical and Corrosion Behavior of a Newly Developed Novel Lean Duplex Stainless Steel

    Science.gov (United States)

    Guo, Yanjun; Hu, Jincheng; Li, Jin; Jiang, Laizhu; Liu, Tianwei; Wu, Yanping

    2014-01-01

    The effect of annealing temperature (1000–1150 °C) on the microstructure evolution, mechanical properties, and pitting corrosion behavior of a newly developed novel lean duplex stainless steel with 20.53Cr-3.45Mn-2.08Ni-0.17N-0.31Mo was studied by means of optical metallographic microscopy (OMM), scanning electron microscopy (SEM), magnetic force microscopy (MFM), scanning Kelvin probe force microscopy (SKPFM), energy dispersive X-ray spectroscopy (EDS), uniaxial tensile tests (UTT), and potentiostatic critical pitting temperature (CPT). The results showed that tensile and yield strength, as well as the pitting corrosion resistance, could be degraded with annealing temperature increasing from 1000 up to 1150 °C. Meanwhile, the elongation at break reached the maximum of 52.7% after annealing at 1050 °C due to the effect of martensite transformation induced plasticity (TRIP). The localized pitting attack preferentially occurred at ferrite phase, indicating that the ferrite phase had inferior pitting corrosion resistance as compared to the austenite phase. With increasing annealing temperature, the pitting resistance equivalent number (PREN) of ferrite phase dropped, while that of the austenite phase rose. Additionally, it was found that ferrite possessed a lower Volta potential than austenite phase. Moreover, the Volta potential difference between ferrite and austenite increased with the annealing temperature, which was well consistent with the difference of PREN. PMID:28788201

  18. Effect of Annealing Temperature on the Mechanical and Corrosion Behavior of a Newly Developed Novel Lean Duplex Stainless Steel

    Directory of Open Access Journals (Sweden)

    Yanjun Guo

    2014-09-01

    Full Text Available The effect of annealing temperature (1000–1150 °C on the microstructure evolution, mechanical properties, and pitting corrosion behavior of a newly developed novel lean duplex stainless steel with 20.53Cr-3.45Mn-2.08Ni-0.17N-0.31Mo was studied by means of optical metallographic microscopy (OMM, scanning electron microscopy (SEM, magnetic force microscopy (MFM, scanning Kelvin probe force microscopy (SKPFM, energy dispersive X-ray spectroscopy (EDS, uniaxial tensile tests (UTT, and potentiostatic critical pitting temperature (CPT. The results showed that tensile and yield strength, as well as the pitting corrosion resistance, could be degraded with annealing temperature increasing from 1000 up to 1150 °C. Meanwhile, the elongation at break reached the maximum of 52.7% after annealing at 1050 °C due to the effect of martensite transformation induced plasticity (TRIP. The localized pitting attack preferentially occurred at ferrite phase, indicating that the ferrite phase had inferior pitting corrosion resistance as compared to the austenite phase. With increasing annealing temperature, the pitting resistance equivalent number (PREN of ferrite phase dropped, while that of the austenite phase rose. Additionally, it was found that ferrite possessed a lower Volta potential than austenite phase. Moreover, the Volta potential difference between ferrite and austenite increased with the annealing temperature, which was well consistent with the difference of PREN.

  19. Effect of Annealing Temperature on the Mechanical and Corrosion Behavior of a Newly Developed Novel Lean Duplex Stainless Steel.

    Science.gov (United States)

    Guo, Yanjun; Hu, Jincheng; Li, Jin; Jiang, Laizhu; Liu, Tianwei; Wu, Yanping

    2014-09-12

    The effect of annealing temperature (1000-1150 °C) on the microstructure evolution, mechanical properties, and pitting corrosion behavior of a newly developed novel lean duplex stainless steel with 20.53Cr-3.45Mn-2.08Ni-0.17N-0.31Mo was studied by means of optical metallographic microscopy (OMM), scanning electron microscopy (SEM), magnetic force microscopy (MFM), scanning Kelvin probe force microscopy (SKPFM), energy dispersive X-ray spectroscopy (EDS), uniaxial tensile tests (UTT), and potentiostatic critical pitting temperature (CPT). The results showed that tensile and yield strength, as well as the pitting corrosion resistance, could be degraded with annealing temperature increasing from 1000 up to 1150 °C. Meanwhile, the elongation at break reached the maximum of 52.7% after annealing at 1050 °C due to the effect of martensite transformation induced plasticity (TRIP). The localized pitting attack preferentially occurred at ferrite phase, indicating that the ferrite phase had inferior pitting corrosion resistance as compared to the austenite phase. With increasing annealing temperature, the pitting resistance equivalent number (PREN) of ferrite phase dropped, while that of the austenite phase rose. Additionally, it was found that ferrite possessed a lower Volta potential than austenite phase. Moreover, the Volta potential difference between ferrite and austenite increased with the annealing temperature, which was well consistent with the difference of PREN.

  20. Effect of contents oil temperature and flow rate in the electrochemical corrosion of the AISI-SAE1020-steel

    Science.gov (United States)

    Cedeño, M. L.; L, E. Vera; Pineda T, Y.

    2017-01-01

    Primary causes of corrosion in components and equipment used in the petroleum industry are due to the density differences present in the multiphase system Water/Hydrocarbon/CO2 as well as the presence of weak particles of carbonic acid. The present research is focus on the study of the corrosion rate of the steel AISI-SAE 1020 under a saturated CO2 multiphase system. The effects of fluid speed, temperature and oil content on the steel corrosion were carried out in an electrode of rotator cylinder and also using electrochemical impedance spectroscopy, and potentiodynamic polarization measurements. The results show that the effect of oil content in the rate of steel corrosion is inversely proportional with the speed of the rotor. Our observations indicate that increasing the rotor speed in systems containing 60% oil or higher produce a simultaneous increase in the degradation rate of materials. Similarly, temperatures higher than 60°C generate layers of siderite that reduce the electrochemical effect.

  1. Influence of relative humidity and temperature on-site corrosion rates

    Directory of Open Access Journals (Sweden)

    Andrade, C.

    1998-09-01

    Full Text Available When the steel rebar depassivates, the corrosion starts to develop at a rate which mainly depends upon the moisture content in the concrete pores. In natural outdoor exposure conditions, the moisture content will depend not only on the relative humidity of the atmosphere but also upon the temperature cycling occurring from day to night. In order to progress in the understanding of the influence of the climatic variables on the corrosion rate of real size structures, several experiments have been performed. Thus the corrosion is measured in solutions simulating the concrete pore solution and simultaneous measurement of oxygen content, Cl-/OH- ratio and conductivity were made. As well measurements in concrete specimens submitted to outdoor conditions was made. The results enable to deduce that the variation of temperature has a multiple simultaneous effect on different parameters which may counter-balance each-other. Thus the oxygen content and the pH decrease and the Cl- increase when temperature rises. The best fit of Icorr is found with resistivity.

    Cuando el acero se despasiva, la corrosión se empieza a desarrollar a una velocidad que depende principalmente de la cantidad de humedad contenida en los poros del hormigón. En estructuras expuestas a la atmósfera, este contenido de humedad dependerá, no sólo de la humedad relativa del ambiente, sino también de las variaciones de temperatura que se producen con los ciclos día-noche. Para avanzar en el conocimiento de la influencia de las variables climáticas en la velocidad de corrosión de estructuras reales, se han llevado a cabo diversos experimentos. Primero se han realizado medidas de corrosión de barras de acero sumergidas en soluciones que simulan la solución de los poros del hormigón sometidas a varias temperaturas y se han registrado sus variaciones de contenido en oxígeno, de la relación Cl-/OH- y de su

  2. Firing technology in practice - temperature, residence time, corrosion; Feuerungstechnik in der Praxis - Temperatur, Verweilzeit, Korrosion

    Energy Technology Data Exchange (ETDEWEB)

    Freimann, P.; Holl, D. [Muellheizkraftwerk Betriebsgesellschaft mbH, Burgkirchen/Alz (Germany)

    1998-09-01

    In a circular dated 1st Sept. 1994, i.e., after the issue of the pertinent planning decision, the Federal Environmental Ministry, BMU, laid down uniform standards on measurements and the parameterisation of the evaluation system for different operation states and loads. Subsequently, TUeV, the German Technical Control Board, prepared the parameterisation curves on the basis of these specifications. The implementation of the BMU paper of 1st Sept. 1994 did not result in any advantage, nor did it lead to a reduction of plant emissions, nor to advantages in the operation of the waste-fuelled cogeneration plant. On the contrary, elevated gas consumption and operating trouble due to frequent feed stops worsened the operating state of the plant. Elevated crude gas temperature in the boiler reduced the lifetime of the two boilers to a critical degree. An operating temperature of 850 C and a residence time of approx. 1 sec. in Burgkirchen waste-fuelled cogeneration plant have not worsened emission values while rendering the plant operable again. [Deutsch] Durch Rundschreiben d. BMU vom 01.09.1994 - also nach Erlass des Planfeststellungsbeschlusses - wurden einheitliche Vorgaben ueber Messungen und Parametrierung des Auswertesystems fuer die verschiedenen Betriebs- bzw. Lastzustaende erlassen. Unter Beruecksichtigung dieser Vorgaben wurden vom TUeV die Parametrierungskurven erstellt. Die Umsetzung des BMU-Papieres vom 01.09.1994 ergab keinerlei Vorteile, weder gab es eine Verringerung der anlagenbedingten Emissionen noch Vorteile fuer den Betrieb des MHKW`s. Im Gegenteil, erhoehte Gasverbraeuche und Betriebsstoerungen durch oftmalige Beschickungsstops verschlechterten den Betriebszustand. Erhoehte Rohgastemperatur im Kessel reduzierten die Lebensdauer der beiden Kessel kritisch. Der Betrieb mit 850 C und mit einer Verweilzeit von ca. 1 sec. fuehrt im MHKW Burgkirchen zu keiner Verschlechterung der Emissionswerte, macht aber die Anlagen wieder betreibbar. (orig./SR)

  3. Tests on dynamic corrosion by water. Influence of the passage of a heat flux on the corrosion kinetics. pH measurement in water at high temperature; Essais de corrosion dynamique par l'eau. Influence du passage d'un flux thermique sur la cinetique de corrosion. Mesure du pH dans l'eau a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Coriou, H.; Grall, L.; Hure, J.; Saint-James, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Berthod [Societe Grenobloise d' Etudes et d' Applications Hydrauliques, 38 (France); Le peintre [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France)

    1958-07-01

    The passage of a heat flux through the surface of a metal placed in a corrosive medium influences the rate of corrosion, these being higher than under adiabatic conditions. The apparatus developed for corrosion tests is described, it is possible to obtain with this equipment: 1) Heat fluxes greater than 200 W/cm{sup 2}, across aluminium canning, which is cooled by water (temperature 50 deg. C), circulating with flow rates of the order of 5 to 6 m/s. 2) Heat fluxes which can go up to 150 W/cm{sup 2}, across canning of zircaloy or stainless steel. The cooling fluid is pressurized water at a temperature around 280 deg. C, the flow-rate of circulation reaching 6 m/s. The results obtained on aluminium canning are studied from the viewpoint of corrosion, paying particular attention to cavitation phenomena which can cause serious damage in certain special circumstances. After developing a glass electrode system capable of supporting high pressures, the authors have investigated materials capable of functioning as a hydrogen electrode and of resisting satisfactorily corrosion by water at 200 deg. C. Various possibilities have been examined: electrodes of special glasses, quartz, metals, with a membrane etc... The results of the various tests and the practical limits of utilisation are given. (author)Fren. [French] Le passage d'un flux thermique a travers la surface d'un metal place dans un milieu corrosif influence les vitesses de corrosion, celles-ci etant plus elevees que dans des conditions adiabatiques. On decrit les appareils mis au point, pour essais de corrosion. Ils permettent d'obtenir: 1) A travers des gaine aluminium des flux thermiques depassant 200 W /cm{sup 2}. Les gaines sont refroidies par l'eau (temperature 50 deg. C), circulant a des vitesses de l'ordre de 5 a 6 m/s. 2) A travers des gaines en zircaloy ou acier inoxydable des flux thermiques pouvant s'elever a 150 W/cm{sup 2}. Le fluide de refroidissement est de l

  4. Correlation between Corrosion Potential and Pitting Potential for AISI 304L Austenitic Stainless Steel in 3.5% NaCl Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Alonso-Falleiros Neusa

    2002-01-01

    Full Text Available 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 correlation between Ecorr and Ep, as well as between the percentage of anodic curves with a well-defined pitting potential and the uncertainty in the determination of Ecorr.

  5. Low Temperature Curing of Hydrogen Silsesquioxane Surface Coatings for Corrosion Protection of Aluminum

    DEFF Research Database (Denmark)

    Lampert, Felix; Jensen, Annemette Hindhede; Møller, Per

    2016-01-01

    Hydrogen Silsesquioxane (HSQ) has shown to be a promising precursor for corrosion protective glass coatings for metallic substrates due to the excellent barrier properties of the films, especially in the application of protective coatings for aluminum in the automotive industry where high chemical...... on aluminum substrates to evaluate the adhesion and corrosion resistance of the films....

  6. Synergistic Effect of Polypyrrole-Intercalated Graphene for Enhanced Corrosion Protection of Aqueous Coating in 3.5% NaCl Solution.

    Science.gov (United States)

    Qiu, Shihui; Li, Wei; Zheng, Wenru; Zhao, Haichao; Wang, Liping

    2017-10-04

    Dispersion of graphene in water and its incorporation into waterborne resin have been rarely researched and hardly achieved owing to its hydrophobicity. Furthermore, it has largely been reported that graphene with impermeability contributed to the improved anticorrosion property. Here, we show that highly concentrated graphene aqueous solution up to 5 mg/mL can be obtained by synthesizing hydrophilic polypyrrole (PPy) nanocolloids as intercalators and ultrasonic vibration. On the basis of π-π interaction between PPy and graphene, stacked graphene sheets are exfoliated to the thickness of three to five layers without increasing defects. The corrosion performance of coatings without and with PPy and graphene is obtained by potential and impedance measurements, Tafel curves, and fitted pore resistance by immersing in a 3.5 wt % NaCl solution. It turns out that composite coating with 0.5 wt % graphene additive exhibits superior anticorrosive ability. The mechanism of intercalated graphene-based coating is interpreted as the synergistic protection of impermeable graphene sheets and self-healing PPy and proved by the identification of corrosion products and the scanning vibrating electrode technique.

  7. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pyatina, T. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-11-01

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  8. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pyatina, T. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-11-14

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  9. Effect of Chromium on Corrosion Behavior of P110 Steels in CO2-H2S Environment with High Pressure and High Temperature

    Science.gov (United States)

    Sun, Jianbo; Sun, Chong; Lin, Xueqiang; Cheng, Xiangkun; Liu, Huifeng

    2016-01-01

    The novel Cr-containing low alloy steels have exhibited good corrosion resistance in CO2 environment, mainly owing to the formation of Cr-enriched corrosion film. In order to evaluate whether it is applicable to the CO2 and H2S coexistence conditions, the corrosion behavior of low-chromium steels in CO2-H2S environment with high pressure and high temperature was investigated using weight loss measurement and surface characterization. The results showed that P110 steel suffered localized corrosion and both 3Cr-P110 and 5Cr-P110 steels exhibited general corrosion. However, the corrosion rate of 5Cr-P110 was the highest among them. The corrosion process of the steels was simultaneously governed by CO2 and H2S. The outer scales on the three steels mainly consisted of FeS1−x crystals, whereas the inner scales on Cr-containing steels comprised of amorphous FeS1−x, Cr(OH)3 and FeCO3, in contrast with the amorphous FeS1−x and FeCO3 mixture film of P110 steel. The more chromium the steel contains, the more chromium compounds the corrosion products contain. The addition of chromium in steels increases the uniformity of the Cr-enriched corrosion scales, eliminates the localized corrosion, but cannot decrease the general corrosion rates. The formation of FeS1−x may interfere with Cr-enriched corrosion scales and lowering the corrosion performance of 3Cr-P110 and 5Cr-P110 steels. PMID:28773328

  10. Effect of Chromium on Corrosion Behavior of P110 Steels in CO2-H2S Environment with High Pressure and High Temperature

    Directory of Open Access Journals (Sweden)

    Jianbo Sun

    2016-03-01

    Full Text Available The novel Cr-containing low alloy steels have exhibited good corrosion resistance in CO2 environment, mainly owing to the formation of Cr-enriched corrosion film. In order to evaluate whether it is applicable to the CO2 and H2S coexistence conditions, the corrosion behavior of low-chromium steels in CO2-H2S environment with high pressure and high temperature was investigated using weight loss measurement and surface characterization. The results showed that P110 steel suffered localized corrosion and both 3Cr-P110 and 5Cr-P110 steels exhibited general corrosion. However, the corrosion rate of 5Cr-P110 was the highest among them. The corrosion process of the steels was simultaneously governed by CO2 and H2S. The outer scales on the three steels mainly consisted of FeS1−x crystals, whereas the inner scales on Cr-containing steels comprised of amorphous FeS1−x, Cr(OH3 and FeCO3, in contrast with the amorphous FeS1−x and FeCO3 mixture film of P110 steel. The more chromium the steel contains, the more chromium compounds the corrosion products contain. The addition of chromium in steels increases the uniformity of the Cr-enriched corrosion scales, eliminates the localized corrosion, but cannot decrease the general corrosion rates. The formation of FeS1−x may interfere with Cr-enriched corrosion scales and lowering the corrosion performance of 3Cr-P110 and 5Cr-P110 steels.

  11. Responses of Microbial Community Composition to Temperature Gradient and Carbon Steel Corrosion in Production Water of Petroleum Reservoir

    Directory of Open Access Journals (Sweden)

    Xiao-Xiao Li

    2017-12-01

    Full Text Available Oil reservoir production systems are usually associated with a temperature gradient and oil production facilities frequently suffer from pipeline corrosion failures. Both bacteria and archaea potentially contribute to biocorrosion of the oil production equipment. Here the response of microbial populations from the petroleum reservoir to temperature gradient and corrosion of carbon steel coupons were investigated under laboratory condition. Carbon steel coupons were exposed to production water from a depth of 1809 m of Jiangsu petroleum reservoir (China and incubated for periods of 160 and 300 days. The incubation temperatures were set at 37, 55, and 65°C to monitoring mesophilic, thermophilic and hyperthermophilic microorganisms associated with anaerobic carbon steel corrosion. The results showed that corrosion rate at 55°C (0.162 ± 0.013 mm year-1 and 37°C (0.138 ± 0.008 mm year-1 were higher than that at 65°C (0.105 ± 0.007 mm year-1, and a dense biofilm was observed on the surface of coupons under all biotic incubations. The microbial community analysis suggests a high frequency of bacterial taxa associated with families Porphyromonadaceae, Enterobacteriaceae, and Spirochaetaceae at all three temperatures. While the majority of known sulfate-reducing bacteria, in particular Desulfotignum, Desulfobulbus and Desulfovibrio spp., were predominantly observed at 37°C; Desulfotomaculum spp., Thermotoga spp. and Thermanaeromonas spp. as well as archaeal members closely related to Thermococcus and Archaeoglobus spp. were substantially enriched at 65°C. Hydrogenotrophic methanogens of the family Methanobacteriaceae were dominant at both 37 and 55°C; acetoclastic Methanosaeta spp. and methyltrophic Methanolobus spp. were enriched at 37°C. These observations show that temperature changes significantly alter the microbial community structure in production fluids and also affected the biocorrosion of carbon steel under anaerobic conditions.

  12. Ceiling temperature and photothermalsensitivity of aqueous MSA-CdTe quantum dots thermometers

    Science.gov (United States)

    Jiang, Xinbing; Shao, Jinyou; Li, Ben Q.

    2017-02-01

    Ceiling temperature, photothermal sensitivity and size effects of aqueous mercaptosuccinic acid modified CdTe quantum dots (MSA-CdTe QDs) are determined from experimental measurements for temperature sensing applications. Measured data show that the ceiling temperature of MSA-CdTe prepared by the hydrothermal process is 60 °C, better than that of CdTe QDs modified by thioglycolic acid (TGA). Aqueous MSA-CdTe QDs exhibit a reversible PL spectral peak wavelength shift within the temperature range from room temperature up to the ceiling temperature 60 °C. With the size of the QDs increasing from 1.9 nm to 3.1 nm, the photothermal sensitivity remains unchanged and a stable linear correlation with a slope of 0.16 nm/ °C exists between the PL spectral peak wavelength position and the temperature. The morphology of QDs was examined under transmission electron microscopy (TEM). The measured emission photoluminescence data by QDs further show that the thermal sensitivity is independent of the size of the QDs for the size range studied. Theoretical analysis is presented to substantiate the experiment results.

  13. Microstructural and aqueous corrosion aspects of laser-surface-melted type 304 SS plasma-coated mild steel

    Science.gov (United States)

    Pujar, M. G.; Dayal, R. K.; Singh Raman, R. K.

    1994-06-01

    Plasma spray deposition of metals, ceramics, or plastics onto base metals to produce wear- and corrosion-resistant surfaces is a promising technique whereby base metal performance can be considerably im-proved. Because these coatings invariably contain pores, voids, and cracks, laser surface melting may be employed to improve their homogeneity. This study focuses on the corrosion performance of laser- sur-face- melted type 304 SS plasma- coated mild steel specimens. Mild steel strips were plasma coated with an approximately 100 to 200 μm thick layer of type 304 by transferred plasma jet. These specimens were sub-sequently laser irradiated using a 3 kW continuous- wave CO2 gas laser. Eight different sets of specimens were selected based on different laser beam travel speeds. Scanning electron microscopic studies of the plasma- coated specimens revealed both pancake and flowery types of deposited particles. Optical micro-scopic studies followed by anodic polarization experiments were carried out on these specimens in IN H2SO4 medium. It was observed that specimens with laser beam interaction times ranging from 30 to 120 ms showed relatively better general corrosion performance than specimens with interaction times of from 15 to 24 ms.

  14. Optical windows for a flow cell to contain aqueous solutions at high pressure and temperature

    Science.gov (United States)

    Bowers, W. J., Jr.; Bean, V. E.; Hurst, W. S.

    1995-02-01

    A flow cell to contain aqueous solutions at pressures up to 40 MPa and temperatures up to 600 °C that is equipped with sapphire windows for the transmission of visible light is described. There are four windows, two for the entrance and exit of a laser beam, and two located at 90° that feature f/1 (53° included angle) collection apertures with a 9 mm diameter unobstructed view for Raman spectroscopy, absorption measurements, or studies using full-field back illumination. The window-to-metal seals are gold o-rings; the metal-to-metal seals are gaskets prepared by pressing a gold o-ring onto a gold foil washer. This cell has been used for two years for Raman studies of aqueous solutions at high pressures and temperatures both below and above the supercritical point of water.

  15. Automated Methods Of Corrosion Measurements

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers; Andersen, Jens Enevold Thaulov; Reeve, John Ch

    1997-01-01

    The chapter describes the following automated measurements: Corrosion Measurements by Titration, Imaging Corrosion by Scanning Probe Microscopy, Critical Pitting Temperature and Application of the Electrochemical Hydrogen Permeation Cell.......The chapter describes the following automated measurements: Corrosion Measurements by Titration, Imaging Corrosion by Scanning Probe Microscopy, Critical Pitting Temperature and Application of the Electrochemical Hydrogen Permeation Cell....

  16. Mechanical, Corrosion and Biological Properties of Room-Temperature Sputtered Aluminum Nitride Films with Dissimilar Nanostructure.

    Science.gov (United States)

    Besleaga, Cristina; Dumitru, Viorel; Trinca, Liliana Marinela; Popa, Adrian-Claudiu; Negrila, Constantin-Catalin; Kołodziejczyk, Łukasz; Luculescu, Catalin-Romeo; Ionescu, Gabriela-Cristina; Ripeanu, Razvan-George; Vladescu, Alina; Stan, George E

    2017-11-17

    Aluminum Nitride (AlN) has been long time being regarded as highly interesting material for developing sensing applications (including biosensors and implantable sensors). AlN, due to its appealing electronic properties, is envisaged lately to serve as a multi-functional biosensing platform. Although generally exploited for its intrinsic piezoelectricity, its surface morphology and mechanical performance (elastic modulus, hardness, wear, scratch and tensile resistance to delamination, adherence to the substrate), corrosion resistance and cytocompatibility are also essential features for high performance sustainable biosensor devices. However, information about AlN suitability for such applications is rather scarce or at best scattered and incomplete. Here, we aim to deliver a comprehensive evaluation of the morpho-structural, compositional, mechanical, electrochemical and biological properties of reactive radio-frequency magnetron sputtered AlN nanostructured thin films with various degrees of c -axis texturing, deposited at a low temperature (~50 °C) on Si (100) substrates. The inter-conditionality elicited between the base pressure level attained in the reactor chamber and crystalline quality of AlN films is highlighted. The potential suitability of nanostructured AlN (in form of thin films) for the realization of various type of sensors (with emphasis on bio-sensors) is thoroughly probed, thus unveiling its advantages and limitations, as well as suggesting paths to safely exploit the remarkable prospects of this type of materials.

  17. Mechanical, Corrosion and Biological Properties of Room-Temperature Sputtered Aluminum Nitride Films with Dissimilar Nanostructure

    Directory of Open Access Journals (Sweden)

    Cristina Besleaga

    2017-11-01

    Full Text Available Aluminum Nitride (AlN has been long time being regarded as highly interesting material for developing sensing applications (including biosensors and implantable sensors. AlN, due to its appealing electronic properties, is envisaged lately to serve as a multi-functional biosensing platform. Although generally exploited for its intrinsic piezoelectricity, its surface morphology and mechanical performance (elastic modulus, hardness, wear, scratch and tensile resistance to delamination, adherence to the substrate, corrosion resistance and cytocompatibility are also essential features for high performance sustainable biosensor devices. However, information about AlN suitability for such applications is rather scarce or at best scattered and incomplete. Here, we aim to deliver a comprehensive evaluation of the morpho-structural, compositional, mechanical, electrochemical and biological properties of reactive radio-frequency magnetron sputtered AlN nanostructured thin films with various degrees of c-axis texturing, deposited at a low temperature (~50 °C on Si (100 substrates. The inter-conditionality elicited between the base pressure level attained in the reactor chamber and crystalline quality of AlN films is highlighted. The potential suitability of nanostructured AlN (in form of thin films for the realization of various type of sensors (with emphasis on bio-sensors is thoroughly probed, thus unveiling its advantages and limitations, as well as suggesting paths to safely exploit the remarkable prospects of this type of materials.

  18. Continuous flowing micro-reactor for aqueous reaction at temperature higher than 100 °C

    OpenAIRE

    Xie, Fei; Wang, Baojun; Wang, Wei; Dong, Tian; Tong, Jianhua; Xia, Shanhong; Wu, Wengang; Li, Zhihong

    2013-01-01

    Some aqueous reactions in biological or chemical fields are accomplished at a high temperature. When the reaction temperature is higher than 100 °C, an autoclave reactor is usually required to elevate the boiling point of the water by creating a high-pressure environment in a closed system. This work presented an alternative continuous flowing microfluidic solution for aqueous reaction with a reaction temperature higher than 100 °C. The pressure regulating function was successfully fulfilled ...

  19. KCl-induced high temperature corrosion of selected commercial alloys. Part II: alumina and silica-formers

    DEFF Research Database (Denmark)

    Kiamehr, Saeed; Dahl, Kristian Vinter; Montgomery, Melanie

    2016-01-01

    -chromium-silicon-oxygen containing layer forms as the innermost corrosion product. The layer was uniformly distributed over the surface and appears to render some protection as this alloy exhibited the best performance among the investigated alloys. To reveal further aspects of the corrosion mechanism, Nimonic 80A was exposed......Laboratory testing on selected alumina and silica-forming alloys was performed to evaluate their performance against high temperature corrosion induced by potassium chloride (KCl). The alloys studied were FeCrAlY, Kanthal APM, Nimonic 80A, 214, 153MA and HR160. Exposure was conducted at 600 °C...... for 168 h in flowing N2(g)+5%O2(g)+15%H2O(g) (vol.%) with samples covered under KCl powder. A KCl-free exposure was also performed for comparison.Corrosion morphology and products were studied with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD...

  20. Temperature and concentration calibration of aqueous polyvinylpyrrolidone (PVP solutions for isotropic diffusion MRI phantoms.

    Directory of Open Access Journals (Sweden)

    Friedrich Wagner

    Full Text Available To use the "apparent diffusion coefficient" (Dapp as a quantitative imaging parameter, well-suited test fluids are essential. In this study, the previously proposed aqueous solutions of polyvinylpyrrolidone (PVP were examined and temperature calibrations were obtained. For example, at a temperature of 20°C, Dapp ranged from 1.594 (95% CI: 1.593, 1.595 μm2/ms to 0.3326 (95% CI: 0. 3304, 0.3348 μm2/ms for PVP-concentrations ranging from 10% (w/w to 50% (w/w using K30 polymer lengths. The temperature dependence of Dapp was found to be so strong that a negligence seems not advisable. The temperature dependence is descriptively modelled by an exponential function exp(c2 (T - 20°C and the determined c2 values are reported, which can be used for temperature calibration. For example, we find the value 0.02952 K-1 for 30% (w/w PVP-concentration and K30 polymer length. In general, aqueous PVP solutions were found to be suitable to produce easily applicable and reliable Dapp-phantoms.

  1. Temperature and concentration calibration of aqueous polyvinylpyrrolidone (PVP) solutions for isotropic diffusion MRI phantoms.

    Science.gov (United States)

    Wagner, Friedrich; Laun, Frederik B; Kuder, Tristan A; Mlynarska, Anna; Maier, Florian; Faust, Jonas; Demberg, Kerstin; Lindemann, Linus; Rivkin, Boris; Nagel, Armin M; Ladd, Mark E; Maier-Hein, Klaus; Bickelhaupt, Sebastian; Bach, Michael

    2017-01-01

    To use the "apparent diffusion coefficient" (Dapp) as a quantitative imaging parameter, well-suited test fluids are essential. In this study, the previously proposed aqueous solutions of polyvinylpyrrolidone (PVP) were examined and temperature calibrations were obtained. For example, at a temperature of 20°C, Dapp ranged from 1.594 (95% CI: 1.593, 1.595) μm2/ms to 0.3326 (95% CI: 0. 3304, 0.3348) μm2/ms for PVP-concentrations ranging from 10% (w/w) to 50% (w/w) using K30 polymer lengths. The temperature dependence of Dapp was found to be so strong that a negligence seems not advisable. The temperature dependence is descriptively modelled by an exponential function exp(c2 (T - 20°C)) and the determined c2 values are reported, which can be used for temperature calibration. For example, we find the value 0.02952 K-1 for 30% (w/w) PVP-concentration and K30 polymer length. In general, aqueous PVP solutions were found to be suitable to produce easily applicable and reliable Dapp-phantoms.

  2. Influence of water quality and temperature on the corrosion of brass; Einfluss der Wasserqualitaet und der Temperatur auf das Korrosionsverhalten von Messing

    Energy Technology Data Exchange (ETDEWEB)

    Donner, J.; Fischer, R. [TU Dresden (Germany). Inst. fuer Wasserchemie; Reissig, H. [Ingenieurbuero fuer Wasserguetefragen, Dresden (Germany); Rahner, D. [TU Dresden (Germany). Inst. fuer Physikalische Chemie und Elektrochemie

    2003-07-01

    In the contribution on correlation between the water quality and the short circuit current in the couple brass and copper are investigated. The examined water quality parameters are temperatures, chloride, sulphate and hydrogencarbonate concentration as well as the pH value. These parameters were varied in experiments and analysed. Predictions about the corrosion tendency can be made from the short circuit current, particularly the corrosion of the investigated brass, and its dependence on investigated water quality parameters. While hydrogencarbonate reduces the short-circuit current, it becomes larger during temperature rise. In the case of chloride and sulphate, changes of the short circuit current depend on the other examined parameters, too. However, chloride has the strongest influence. (orig.)

  3. Enhanced High Temperature Corrosion Resistance in Advanced Fossil Energy Systems by Nano-Passive Layer Formation

    Energy Technology Data Exchange (ETDEWEB)

    Arnold R. Marder

    2007-06-14

    Due to their excellent corrosion resistance, iron aluminum alloys are currently being considered for use as weld claddings in fossil fuel fired power plants. The susceptibility to hydrogen cracking of these alloys at higher aluminum concentrations has highlighted the need for research into the effect of chromium additions on the corrosion resistance of lower aluminum alloys. In the present work, three iron aluminum alloys were exposed to simulated coal combustion environments at 500 C and 700 C for both short (100 hours) and long (5,000 hours) isothermal durations. Scanning electron microscopy was used to analyze the corrosion products. All alloys exhibited excellent corrosion resistance in the short term tests. For longer exposures, increasing the aluminum concentration was beneficial to the corrosion resistance. The addition of chromium to the binary iron aluminum alloy prevented the formation iron sulfide and resulted in lower corrosion kinetics. A classification of the corrosion products that developed on these alloys is presented. Scanning transmission electron microscopy (STEM) of the as-corroded coupons revealed that chromium was able to form chromium sulfides only on the higher aluminum alloy, thereby preventing the formation of deleterious iron sulfides. When the aluminum concentration was too low to permit selective oxidation of only aluminum (upon initial exposure to the corrosion environment), the formation of chromium oxide alongside the aluminum oxide led to depletion of chromium beneath the oxide layer. Upon penetration of sulfur through the oxide into this depletion layer, iron sulfides (rather than chromium sulfides) were found to form on the low aluminum alloy. Thus, it was found in this work that the role of chromium on alloy corrosion resistance was strongly effected by the aluminum concentration of the alloy. STEM analysis also revealed the encapsulation of external iron sulfide products with a thin layer of aluminum oxide, which may provide a

  4. Improvement of erosion and erosion corrosion resistance of AISI420 stainless steel by low temperature plasma nitriding

    Science.gov (United States)

    Xi, Yun-tao; Liu, Dao-xin; Han, Dong

    2008-07-01

    Plasma nitriding experiments were carried out with DC-pulsed plasma in 25% N 2 + 75% H 2 atmosphere at low temperature (350 °C) and normal temperature (550 °C) for 15 h. The composition, microstructure, microhardness profiles, residual stress profiles and electrochemical impedance spectrum analyses of the nitrided samples were examined. The influence of plasma nitriding on the erosion and erosion-corrosion resistance of AISI 420 martensitic stainless steel was investigated using a jet solid particle erosion tester and a slurry erosion-corrosion tester. Results showed that the 350 °C nitriding layer was dominated by ɛ-Fe 3N and α N phase, a supersaturated nitrogen solid solution. However, nitrogen would react with Cr in the steel to form CrN precipitates directly during 550 °C nitriding, which would lead to the depletion of Cr in the solid solution phase of the nitrided layer. Both 350 and 550 °C plasma nitriding could improve the erosion resistance of AISI420 stainless steel under dry erosion, but the former showed better results. In both neutral and acid environment, while the erosion-corrosion resistance of AISI 420 was improved by means of 350 °C nitriding, it was decreased through 550 °C nitriding.

  5. The effects of temperature and aeration on the corrosion of A508III low alloy steel in boric acid solutions at 25-95 °C

    Science.gov (United States)

    Xiao, Qian; Lu, Zhanpeng; Chen, Junjie; Yao, Meiyi; Chen, Zhen; Ejaz, Ahsan

    2016-11-01

    The effects of temperature, solution composition and dissolved oxygen on the corrosion rate and electrochemical behavior of an A508III low alloy steel in boric acid solution with lithium hydroxide at 25-95 °C are investigated. In aerated solutions, increasing the boric acid concentration increases the corrosion rate and the anodic current density. The corrosion rate in deaerated solutions increases with increasing temperature. A corrosion rate peak value is found at approximately 75 °C in aerated solutions. Increasing temperature increases the oxygen diffusion coefficient, decreases the dissolved oxygen concentration, accelerates the hydrogen evolution reaction, and accelerates both the active dissolution and the film forming reactions. Increasing dissolved oxygen concentration does not significantly affect the corrosion rate at 50 and 60 °C, increases the corrosion rate at 70 and 80 °C, and decreases the corrosion rate at 87.5 and 95 °C in a high concentration boric acid solution with lithium hydroxide.

  6. Low temperature growth and optical properties of ZnO nanowires using an aqueous solution method.

    Science.gov (United States)

    Chu, Manh-Hung; Lee, Joon-Hyung; Kim, Jeong-Joo; Kim, Kyeong-Won; Norton, D P; Heo, Young-Woo

    2012-02-01

    ZnO nanowires were grown on indium tin oxide (ITO) coated glass substrates at a low temperature of 90 degrees C using an aqueous solution method. The ZnO seeds were coated on the ITO thin films by using a spin coater. ZnO nanowires were formed in an aqueous solution containing zinc nitrate hexahydrate (Zn(NO3)2 x 6H2O) and hexamethylenetetramine (C6H12N4). The pH value and concentration of the solution play an important role in the growth and morphologies of ZnO nanowires. The size of ZnO naonowires increased as the concentration of the solution increased. It was formed with a top surface of hexagonal and tapered shape at low and high pH values respectively. Additionally, the single crystalline structure and optical property of the ZnO nanowires were investigated using high-resolution transmission electron microscopy and photoluminescence spectroscopy.

  7. The effect of temperature on radiolysis of iodide ion diluted aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gorbovitskaya, T.; Tiliks, J. [Latvia Univ., Lab. of Radiation Chemistry, Riga (Latvia)

    1996-12-01

    To investigate the radiolysis of iodine containing aqueous solutions a flow type facility (ITF) has a possibility to irradiate aqueous solutions in the steel vessel with {sup 60}Co {gamma}-rays and continuously (on line) to analyze the products of radiolysis both in liquid and in gaseous phases. By means of ITF the formation of I{sub ox} (I{sub 2} + I{sub 3}{sup -} + HOI), IO{sub 3}{sup -}, H{sub 2}O{sub 2} was studied in 10{sup -5} - 10{sup -3} mol/dm{sup 3} CsI aqueous solutions by their radiolysis at dose rate 4.5 kGv/h for six hours in region of temperatures from 313 to 404 K. Some experiments in glass ampoules were also performed. The steady-state concentrations of I{sub ox} and IO{sub 3}{sup -} decreased with increasing temperature as linear function of inverted temperature. The effect decreased with decreasing concentration of iodide ion. As the result, at high temperatures (T{>=}380 K) the steady-state concentration of I{sub ox} does not depend essentially on the iodide ion initial concentration. Molecular iodine (I{sub 2}) released from the solution was the main radiolysis product in gaseous phase. Its steady-state concentration increased with increasing temperature because of iodine solubility in the water and decreased at the same time because the radiolytic iodine concentrations decreased. Therefore the most volatility of irradiated 10{sup -3} and 10{sup -4}M CsI solutions was observed at the temperature about 350 K. The volatility of 10{sup -5}M solutions gradually decreased with increasing temperature. The experimental data were explained on the base of the hypothesis that the reaction between I{sub 2} and radiolytic H{sub 2}O{sub 2} was the limit one determining the temperature dependence of I{sub ox} and IO{sub 3}{sup -}steady-state concentrations. Its activation energy was estimated to be 27,5 kcal.mol{sup -1}. The temperature dependence for reaction (IO{sup -} + H{sub 2}O{sub 2}) was also estimated. (author) 8 figs., 1 tab., 17 refs.

  8. High-temperature Corrosion Resistance of Composite Coating Prepared by Micro-arc Oxidation Combined with Pack Cementation Aluminizing

    Directory of Open Access Journals (Sweden)

    HUANG Zu-jiang

    2018-01-01

    Full Text Available Al2O3 ceramic film was obtained by micro-arc oxidation (MAO process on Al/C103 specimen, which was prepared by pack cementation aluminizing technology on C103 niobium alloy. With the aid of XRD and SEM equipped with EDS, chemical compositions and microstructures of the composite coatings before and after high-temperature corrosion were analyzed. The behavior and mechanism of the composite coatings in high-temperature oxidation and hot corrosion were also investigated. The results indicate that oxidation mass gain at 1000℃ for 10h of the Al/C103 specimen is 6.98mg/cm2, and it is 2.89mg/cm2 of the MAO/Al/C103 specimen. However, the mass gain of MAO/Al/C103 specimen (57.52mg/cm2 is higher than that of Al/C103 specimen (28.08mg/cm2 after oxidation 20h. After hot corrosion in 75%Na2SO4 and 25%NaCl at 900℃ for 50h, the mass gain of Al/C103 and MAO/Al/C103 specimens are 70.54mg/cm2 and 55.71mg/cm2 respectively, Al2O3 and perovskite NaNbO3 phases are formed on the surface; the diffusion of molten salt is suppressed, due to part of NaNbO3 accumulated in the MAO micropores. Therefore, MAO/Al/C103 specimen exhibits better hot corrosion resistance.

  9. Influence of pre-deformation, sensitization and oxidation in high temperature water on corrosion resistance of AISI 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Jinlong, E-mail: ljltsinghua@126.com [Beijing Key Laboratory of Fine Ceramics, Institute of Nuclear and New Energy Technology, Tsinghua University, Zhongguancun Street, Haidian District, Beijing 100084 (China); State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China); Liang, Tongxiang [Beijing Key Laboratory of Fine Ceramics, Institute of Nuclear and New Energy Technology, Tsinghua University, Zhongguancun Street, Haidian District, Beijing 100084 (China); State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China); Luo, Hongyun [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Xueyuan Road 37, Beijing 100191 (China)

    2016-12-01

    Highlights: • The pre-strain accelerated desensitization and sensitization for austenitic stainless steels. • Low temperature sensitization (carbide precipitation) induced α′-martensite. • The sensitization level could affect directly corrosion resistance of the oxide film. - Abstract: The effects of pre-deformation on sensitization of AISI 304 stainless steel were investigated by the double loop electrochemical potentiokinetic reactivation test. The effects of pre-deformation and sensitization on high temperature oxidized film formed in high temperature water were analyzed by a XRD and SEM. The electrochemical impedance spectroscopy at room temperature was used to study corrosion resistance of oxidized film. The point defect density of oxidized film was calculated by Mott–Schottky plots. The results showed that the value of the degree of sensitization first decreased and then slight increased with the increasing of engineering strain. Moreover, low temperature promoted to form sensitization induced “secondary” α′-martensite. The sample with 20% engineering strain had higher impedance value than other samples. The result was supported by further Mott–Schottky experiments. Considering increased α′-martensite with the increasing of strain, the results of the impedance were more consistent with values of the degree of sensitization.

  10. Large-Scale Synthesis of Silver Nanoparticles by Aqueous Reduction for Low-Temperature Sintering Bonding

    Directory of Open Access Journals (Sweden)

    Qiu Xiliang

    2014-01-01

    Full Text Available Silver nanoparticles with average diameter of 22.4 nm were prepared by aqueous reduction method for low-temperature sintering bonding application. The reaction temperature and PVP concentration, which are the influential factors of nanoparticle characteristics, were investigated during reduction process. In our research, monodispersity of nanoparticles was remarkably improved while unfavorable agglomeration was avoided with the AgNO3/PVP mass ratio of 1 : 4 at the reaction temperature 30°C. Besides, copper pads were successfully bonded using sintering paste employing fresh silver nanoparticles with diameter of 20~35 nm at 200°C. In addition, after morphology of the bonding joint was analysed by scanning electron microscope (SEM, the porous sintering characteristics were confirmed.

  11. Center of Competence in High Temperature Corrosion, HTC. Report of activities during stage 3, 2000-10-01--2003-12-31

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Lars-Gunnar [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Inorganic Chemistry

    2004-09-01

    HTC, the Swedish High Temperature Corrosion Centre, is a Swedish national competence centre jointly financed by the Swedish National Energy Agency, Chalmers Univ. of Technology and twelve member companies. HTC research has the following objectives: Improved materials performance resulting in increased service life of installations leading to lower maintenance and repair costs. Improved process performance resulting in improved energy efficiency and decreased emissions to the environment To achieve this, HTC aims to establish new and fundamental knowledge on High-Temperature Corrosion. The following research themes are pursued: High temperature corrosion in combustion gases and under deposits; Interaction of corrosion and mechanical factors such as erosion and fatigue. Main achievements during stage 3: HTC is at the cutting edge of science in certain areas of high temperature corrosion research. e.g., on the effect of water vapor on the corrosion of FeCr alloys, on the oxidation of platinum aluminide coatings and on the kinetics of the reactions at the oxide-gas interface.

  12. Corrosion of oxide nuclear fuels in high-temperature water (LWBR Development Program

    Energy Technology Data Exchange (ETDEWEB)

    Markowitz, J M; Clayton, J C

    1970-02-01

    The corrosion behavior of a group of nuclear fuel oxides including urania, thoria, urania-zirconia, urania-calcia-zirconia, and urania-thoria has been studied in 360/sup 0/C, pH 10 flowing water, both degassed and oxygenated (5 and 100 ppM). Weight gains of the specimens, which were of plate or cylindrical pellet shape, were determined periodically during the corrosion exposures, some of which were as long as 500 days; in addition, ceramographic examinations, x-ray diffraction measurements, and chemical analyses were carried out on selected specimens. The results are summarized and discussed. (NSA 24: 25764)

  13. Electropolymerization of phenol on a vitreous carbon electrode in alkaline aqueous solution at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Belhadj Tahar, Noureddine [Departement de Chimie, Faculte des Sciences de Monastir, Universite de Monastir, Route de Kairouan, 5000 Monastir (Tunisia); Savall, Andre, E-mail: savall@chimie.ups-tlse.f [Laboratoire de Genie Chimique, CNRS, Universite Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse (France)

    2009-12-30

    Electrochemical oxidation of phenol in basic aqueous solution has been studied on a vitreous carbon electrode at different temperatures in the range of 25-85 deg. C by cyclic voltammetry and chronoamperometry techniques. The electrochemical oxidation of phenol led to a complete deactivation of the electrode, whatever the temperature used, as a result of the deposition of an adhesive and insulating polymeric film. The electrochemical activity of the electrode was progressively restored by repeated potential scans in the range of water stability only when conducted at high temperatures; electrode reactivation was explained by an increase in the polymeric film permeability for both electrons (electron tunneling) and phenol molecules (diffusion). Chronoamperometric measurements carried out in the potential region of water stability have shown that electrode passivation was reduced or prevented at high temperatures. For chronoamperometry performed at the onset of oxygen evolution, the electrode remained active even at low temperatures because the discharge of water involved the production of hydroxyl radicals that destructively oxidized the polymeric film. The effect of temperature on electrode reactivation was determined by the measurement of current at an electrolysis time of 300 s; an increase of the temperature from 25 to 85 deg. C amplified the current from 0.212 to 5.373 mA.

  14. Probing Ionic Liquid Aqueous Solutions Using Temperature of Maximum Density Isotope Effects

    Directory of Open Access Journals (Sweden)

    Mohammad Tariq

    2013-03-01

    Full Text Available This work is a new development of an extensive research program that is investigating for the first time shifts in the temperature of maximum density (TMD of aqueous solutions caused by ionic liquid solutes. In the present case we have compared the shifts caused by three ionic liquid solutes with a common cation—1-ethyl-3-methylimidazolium coupled with acetate, ethylsulfate and tetracyanoborate anions—in normal and deuterated water solutions. The observed differences are discussed in terms of the nature of the corresponding anion-water interactions.

  15. Improved AIOMFAC model parameterisation of the temperature dependence of activity coefficients for aqueous organic mixtures

    Science.gov (United States)

    Ganbavale, G.; Zuend, A.; Marcolli, C.; Peter, T.

    2015-01-01

    This study presents a new, improved parameterisation of the temperature dependence of activity coefficients in the AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) model applicable for aqueous as well as water-free organic solutions. For electrolyte-free organic and organic-water mixtures the AIOMFAC model uses a group-contribution approach based on UNIFAC (UNIversal quasi-chemical Functional-group Activity Coefficients). This group-contribution approach explicitly accounts for interactions among organic functional groups and between organic functional groups and water. The previous AIOMFAC version uses a simple parameterisation of the temperature dependence of activity coefficients, aimed to be applicable in the temperature range from ~ 275 to ~ 400 K. With the goal to improve the description of a wide variety of organic compounds found in atmospheric aerosols, we extend the AIOMFAC parameterisation for the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon to atmospherically relevant low temperatures. To this end we introduce a new parameterisation for the temperature dependence. The improved temperature dependence parameterisation is derived from classical thermodynamic theory by describing effects from changes in molar enthalpy and heat capacity of a multi-component system. Thermodynamic equilibrium data of aqueous organic and water-free organic mixtures from the literature are carefully assessed and complemented with new measurements to establish a comprehensive database, covering a wide temperature range (~ 190 to ~ 440 K) for many of the functional group combinations considered. Different experimental data types and their processing for the estimation of AIOMFAC model parameters are discussed. The new AIOMFAC parameterisation for the temperature dependence of activity coefficients from low to high temperatures shows an overall improvement of 28% in

  16. Effect of High Temperature Hot Corrosion on the Compression Creep Behavior of 12Cr1MoV Alloys

    Science.gov (United States)

    He, Jianjun; Xiong, Weizhou

    2017-10-01

    This paper highlights the effect of 70 %NaCl-30 %KCl salt mixture on compression creep properties of 12Cr1MoV alloys at 100 MPa (948.15 K, 973.15 K and 998.15 K) in air using bare specimens and specimens in corrosive environment. The corrosive specimens were also tested at 923.15 K (150 MPa, 175 MPa and 200 MPa). Experimental results showed that the specimen in chloride mixture showed relatively high compression creep strain and steady-state creep rates compared with the bare specimen, and this effect accelerated with the increased temperature, especially when it was above 973.15 K. The creep mechanisms of the specimen in chloride mixture were inferred from gliding and climbing of dislocations of the stress exponent. Damage of hot corrosion in creep deformation was found to be associated with the layer fracture attributing to the initiation and propagation from the intergranular cracks and reduction of the bare area caused by the internal transgranular attack of chloride mixture.

  17. Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

    Science.gov (United States)

    Lee, Jung Gu; Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku

    2017-05-01

    The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments.

  18. High temperature solution-nitriding and low-temperature nitriding of AISI 316: Effect on pitting potential and crevice corrosion performance

    DEFF Research Database (Denmark)

    Bottoli, Federico; Jellesen, Morten Stendahl; Christiansen, Thomas Lundin

    2018-01-01

    Stainless steels grade AISI 316 was subjected to high temperature solution nitriding and low-temperature nitriding in order to dissolve various amounts of nitrogen in the bulk (up to approx. 0.45wt%) and in a surface layer (up to approx. 13wt%), respectively. Potentiodynamic polarization tests in...... at the material surface through low-temperature nitriding resulted in a considerable improvement of the pitting potential and the crevice corrosion performance of the steels.......Stainless steels grade AISI 316 was subjected to high temperature solution nitriding and low-temperature nitriding in order to dissolve various amounts of nitrogen in the bulk (up to approx. 0.45wt%) and in a surface layer (up to approx. 13wt%), respectively. Potentiodynamic polarization tests...... in a 0.1M NaCl solution and crevice corrosion immersion tests in 3wt% FeCl3 solution were studied before and after the bulk and surface treatments.Nitrogen addition in the bulk proved to have a beneficial effect on the pitting resistance of the alloy. The formation of a zone of expanded austenite...

  19. Electrochemical Studies of Corrosion in Liquid Electrolytes for Energy Conversion Applications at Elevated Temperatures

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey Valerievich; Petrushina, Irina; Bjerrum, Niels J.

    2016-01-01

    Stainless steels (AISI 316, 321 and 347), high-nickel alloys (Hasteloy®C-276 and Inconel®625), tantalum, nickel, titanium, tungsten, molybdenum, niobium, platinum, and gold were tested for corrosion resistance in molten KH2PO4 (or KH2PO4-K2H2P2O7) as a promising electrolyte for the intermediate-t...

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

    Directory of Open Access Journals (Sweden)

    Esmaeil Sadeghimeresht

    2017-09-01

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

  1. Cr(III) solubility in aqueous fluids at high pressures and temperatures

    Science.gov (United States)

    Watenphul, Anke; Schmidt, Christian; Jahn, Sandro

    2014-02-01

    Trivalent chromium is generally considered relatively insoluble in aqueous fluids and melts. However, numerous counterexamples in nature indicate Cr(III) mobilization by aqueous fluids during metamorphism or hydrothermal alteration of chromite-bearing rocks, or by pegmatite melts. So far, very little is known about the chromium concentrations and speciation in such fluids. In this study, the solubility of eskolaite (Cr2O3) in 1.6-4.2 m aqueous HCl solutions was determined in situ at elevated pressures up to 1 GPa and temperatures ranging between 400 and 700 °C using synchrotron micro-X-ray fluorescence spectroscopy (μ-XRF). Determined concentrations of dissolved Cr ranged between about 900-18,000 ppm, with the highest concentrations found at 500 °C and 861 MPa. The Cr(III) solubility in aqueous HCl fluids is retrograde in the studied temperature range and increases with pressure. In addition, Cr(III) complexation in these fluids was explored by Raman spectroscopy on a 12.3 mass% HCl fluid in equilibrium with eskolaite at 400 and 600 °C, 0.3-1.6 GPa. All spectra show two prominent Cr-Cl stretching bands at about 275 and 325 cm-1, which display some fine structure, and in some spectra weak bands in the region between 380 and 500 cm-1. The sum of the integrated intensities of the two dominant bands reveals qualitatively the same changes with temperature along an isochore, with pressure at constant temperature, and with the time required for equilibration as the Cr(III) concentrations in the fluid determined by μ-XRF. Complementary ab initio molecular dynamics simulations of a 4 m HCl solution at two different densities (0.8 and 0.97 g/cm3) and temperatures (427 and 727 °C) were performed to investigate the vibrational properties of various(O)y3-x and (O)y(OH)z3-x-z complexes with 3⩽x+z⩽4 and 0⩽y⩽2. Quasi-normal mode analysis reveals that both the tetrahedral symmetric and antisymmetric Cr-Cl stretching vibrations of CrCl4(H2O)0-2- have characteristic

  2. Effect of Carbide Dissolution on Chlorine Induced High Temperature Corrosion of HVOF and HVAF Sprayed Cr3C2-NiCrMoNb Coatings

    Science.gov (United States)

    Fantozzi, D.; Matikainen, V.; Uusitalo, M.; Koivuluoto, H.; Vuoristo, P.

    2018-01-01

    Highly corrosion- and wear-resistant thermally sprayed chromium carbide (Cr3C2)-based cermet coatings are nowadays a potential highly durable solution to allow traditional fluidized bed combustors (FBC) to be operated with ecological waste and biomass fuels. However, the heat input of thermal spray causes carbide dissolution in the metal binder. This results in the formation of carbon saturated metastable phases, which can affect the behavior of the materials during exposure. This study analyses the effect of carbide dissolution in the metal matrix of Cr3C2-50NiCrMoNb coatings and its effect on chlorine-induced high-temperature corrosion. Four coatings were thermally sprayed with HVAF and HVOF techniques in order to obtain microstructures with increasing amount of carbide dissolution in the metal matrix. The coatings were heat-treated in an inert argon atmosphere to induce secondary carbide precipitation. As-sprayed and heat-treated self-standing coatings were covered with KCl, and their corrosion resistance was investigated with thermogravimetric analysis (TGA) and ordinary high-temperature corrosion test at 550 °C for 4 and 72 h, respectively. High carbon dissolution in the metal matrix appeared to be detrimental against chlorine-induced high-temperature corrosion. The microstructural changes induced by the heat treatment hindered the corrosion onset in the coatings.

  3. Temperature effect on corrosion fatigue strength of coated ship structural steel; Zosen`yoko tosozai no fushoku hiro kyodo ni okeru ondo no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Takanashi, M.; Fuji, A.; Kojima, M.; Kitagawa, M. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan); Kobayashi, Y. [Ship Research Inst., Tokyo (Japan); Kumakura, Y.

    1997-08-01

    The corrosion fatigue life was obtained using uncoated and tar epoxy resin specimens to clarify the temperature effect. The life curve for corrosion fatigue of machined and uncoated steel in the air and sea was obtained. The fatigue strength of uncoated steel largely decreases in the sea and breaks even in the nominal stress range of less than 1/2 of the fatigue limit in the air. The effect of temperature on the coated steel is represented by a corrosion coefficient. The steel coated at 25{degree}C is 1/1.03 to 1/1.13 at 40 to 60{degree}C. This showed that the fatigue strength decreases when the temperature exceeds 25{degree}C. However, it has not such tendency and significance that are represented quantitatively. There is a slight difference in the short-life area between the crack generation life and breaking life. However, the long-life area has no significance that influences the whole evaluation. In the long-life corrosion fatigue, the crack occurs from the corrosion pit due to the exposure below the coated film and progresses in the base material before the coated film is destroyed. The effect of the corrosion pit remarkably appears at a low-stress level. 14 refs., 14 figs., 4 tabs.

  4. Sputter-ion plating of coatings for protection of gas-turbine blades against high-temperature oxidation and corrosion

    Science.gov (United States)

    Coad, J. P.; Restall, J. E.

    1982-01-01

    Considerable effort is being devoted to the development of overlay coatings for protecting critical components such as turbine blades against high-temperature oxidation, corrosion, and erosion damage in service. The most commercially advanced methods for depositing coatings are electron-beam evaporation and plasma spraying. Sputter-ion plating (SIP) offers a potentially cheaper and simpler alternative method for depositing overlays. Experimental work on SIP of Co-Cr-Al-Y and Ni-Cr-Al-Ti alloy coatings is described. Results are presented of metallographic assessment of these coatings, and of the results obtained from high-velocity testing using a gas-turbine simulator rig.

  5. Catalytic Palladium Film Deposited by Scalable Low-Temperature Aqueous Combustion.

    Science.gov (United States)

    Voskanyan, Albert A; Li, Chi-Ying Vanessa; Chan, Kwong-Yu

    2017-09-27

    This article describes a novel method for depositing a dense, high quality palladium thin film via a one-step aqueous combustion process which can be easily scaled up. Film deposition of Pd from aqueous solutions by conventional chemical or electrochemical methods is inhibited by hydrogen embrittlement, thus resulting in a brittle palladium film. The method outlined in this work allows a direct aqueous solution deposition of a mirror-bright, durable Pd film on substrates including glass and glassy carbon. This simple procedure has many advantages including a very high deposition rate (>10 cm 2 min -1 ) and a relatively low deposition temperature (250 °C), which makes it suitable for large-scale industrial applications. Although preparation of various high-quality oxide films has been successfully accomplished via solution combustion synthesis (SCS) before, this article presents the first report on direct SCS production of a metallic film. The mechanism of Pd film formation is discussed with the identification of a complex formed between palladium nitrate and glycine at low temperature. The catalytic properties and stability of films are successfully tested in alcohol electrooxidation and electrochemical oxygen reduction reaction. It was observed that combustion deposited Pd film on a glassy carbon electrode showed excellent catalytic activity in ethanol oxidation without using any binder or additive. We also report for the first time the concept of a reusable "catalytic flask" as illustrated by the Suzuki-Miyaura cross-coupling reaction. The Pd film uniformly covers the inner walls of the flask and eliminates the catalyst separation step. We believe the innovative concept of a reusable catalytic flask is very promising and has the required features to become a commercial product in the future.

  6. Novel enhanced applications of QSPR models: Temperature dependence of aqueous solubility.

    Science.gov (United States)

    Klimenko, Kyrylo; Kuz'min, Victor; Ognichenko, Liudmila; Gorb, Leonid; Shukla, Manoj; Vinas, Natalia; Perkins, Edward; Polishchuk, Pavel; Artemenko, Anatoly; Leszczynski, Jerzy

    2016-08-15

    A model developed to predict aqueous solubility at different temperatures has been proposed based on quantitative structure-property relationships (QSPR) methodology. The prediction consists of two steps. The first one predicts the value of k parameter in the linear equation lgSw=kT+c, where Sw is the value of solubility and T is the value of temperature. The second step uses Random Forest technique to create high-efficiency QSPR model. The performance of the model is assessed using cross-validation and external test set prediction. Predictive capacity of developed model is compared with COSMO-RS approximation, which has quantum chemical and thermodynamic foundations. The comparison shows slightly better prediction ability for the QSPR model presented in this publication. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  7. Dependences of the osmotic coefficients of aqueous calcium chloride solutions on concentration at different temperatures

    Science.gov (United States)

    Rudakov, A. M.; Sergievskii, V. V.; Nagovitsyna, O. A.

    2017-12-01

    A model that considers the contributions from hydration, ion association, and electrostatic interactions to the nonideality of 2‒1 electrolyte solutions is substantiated. The parameters of the model's equations are the mean ion hydration number, the spread of the distribution of hydrated ion stoichiometric coefficients in the standard state, and the number of association. The model is successfully used to describe literature experimental data on the concentration dependence of osmotic coefficients of aqueous CaCl2 solutions at temperatures ranging from 0 to 100°C. The modeling of the above systems shows that as the temperature rises, the hydration number falls slightly, the distribution of the hydration number broadens, and the ion paring of the salt rises by the first degree.

  8. Effect of temperature and heat fluxes on the corrosion's damage nature for mild and stainless steels in neutral chloride solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kaluzhina, S.A. [Voronezh State University, University Sq.1, 394006 Voronezh (Russian Federation); Malygin, A.V. [JSC Voronezhsynthezkauchuk, Leninsky Av. 2, 394014 Voronezh (Russian Federation); Vigdorovitch, V.V. [Derzhavin State University, International St. 33, 392622 Tambov (Russian Federation)

    2004-07-01

    The detail research of the corrosion-electrochemical behavior of two types steels - mild steel (0.1%C) and stainless steel 12FeCr18Ni10Ti in series chloride solutions under elevated temperature and heat flux on interface has been carried out in the present work using the special plant and the complex electrochemical and microscopic methods. The comparative data has shown that the temperature increase is stimulating as the active alloy's corrosion (mild steel), so the passive alloy's corrosion (12FeCr18Ni10Ti).However at the last case the temperature effect is being higher because the thermal de-passivation of the stainless steel which undergoes pit corrosion under t > 50 deg C. The heat-transfer role in the studied systems is ambiguous. The corrosion rate of heat-transferring electrode from mild steel exceeds the thermo-equilibrium with solution electrode's corrosion rate because of intensification of the oxygen reduction cathodic process. The opposite effect has been established for steel 12FeCr18Ni10Ti where the oxygen flux's strengthening from cold solution to the heated surface transfers the alloy to the most stable passive state and increases its resistance to general and local corrosion. The experimental results demonstrates that the thermal condition's influence on the nature and corrosion intensity of the investigated steels is being commensurable by effect's degree with their composition and showing strictly individually. (authors)

  9. Development of models and online diagnostic monitors of the high-temperature corrosion of refractories in oxy/fuel glass furnaces : final project report.

    Energy Technology Data Exchange (ETDEWEB)

    Griffiths, Stewart K.; Gupta, Amul (Monofrax Inc., Falconer, NY); Walsh, Peter M.; Rice, Steven F.; Velez, Mariano (University of Missouri, Rolla, MO); Allendorf, Mark D.; Pecoraro, George A. (PPG Industries, Inc., Pittsburgh, PA); Nilson, Robert H.; Wolfe, H. Edward (ANH Refractories, Pittsburgh, PA); Yang, Nancy Y. C.; Bugeat, Benjamin () American Air Liquide, Countryside, IL); Spear, Karl E. (Pennsylvania State University, University Park, PA); Marin, Ovidiu () American Air Liquide, Countryside, IL); Ghani, M. Usman (American Air Liquide, Countryside, IL)

    2005-02-01

    This report summarizes the results of a five-year effort to understand the mechanisms and develop models that predict the corrosion of refractories in oxygen-fuel glass-melting furnaces. Thermodynamic data for the Si-O-(Na or K) and Al-O-(Na or K) systems are reported, allowing equilibrium calculations to be performed to evaluate corrosion of silica- and alumina-based refractories under typical furnace operating conditions. A detailed analysis of processes contributing to corrosion is also presented. Using this analysis, a model of the corrosion process was developed and used to predict corrosion rates in an actual industrial glass furnace. The rate-limiting process is most likely the transport of NaOH(gas) through the mass-transport boundary layer from the furnace atmosphere to the crown surface. Corrosion rates predicted on this basis are in better agreement with observation than those produced by any other mechanism, although the absolute values are highly sensitive to the crown temperature and the NaOH(gas) concentration at equilibrium and at the edge of the boundary layer. Finally, the project explored the development of excimer laser induced fragmentation (ELIF) fluorescence spectroscopy for the detection of gas-phase alkali hydroxides (e.g., NaOH) that are predicted to be the key species causing accelerated corrosion in these furnaces. The development of ELIF and the construction of field-portable instrumentation for glass furnace applications are reported and the method is shown to be effective in industrial settings.

  10. Efficient inverted polymer solar cells using low-temperature zinc oxide interlayer processed from aqueous solution

    Science.gov (United States)

    Chen, Dazheng; Zhang, Chunfu; Heng, Ting; Wei, Wei; Wang, Zhizhe; Han, Genquan; Feng, Qian; Hao, Yue; Zhang, Jincheng

    2015-04-01

    In this work, an aqueous solution method that entails processing at low temperatures is utilized to deposit a ZnO interlayer in poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl C61 butyric acid methyl ester-based inverted polymer solar cells (PSCs). The effect of ZnO annealing temperature from 50 to 150 °C on PSC performance is systemically studied and it is found that the transition point is approximately 80 °C. When the ZnO annealing temperature is higher than 80 °C, PSCs show similar current density-voltage (J-V) characteristics and achieve a power conversion efficiency higher than 3.5%. Transmittance spectrum, PL spectrum, and surface morphology studies show that an annealing temperature above 80 °C is sufficient for ZnO to achieve a relatively good quality, and that a higher temperature only slightly improves ZnO quality, which is confirmed from statistical results. Furthermore, flexible PSCs based on PET substrates show a comparable power conversion efficiency and good flexibility.

  11. Characterization and corrosion behavior of F6NM stainless steel treated in high temperature water

    Science.gov (United States)

    Li, Zheng-yang; Cai, Zhen-bing; Yang, Wen-jin; Shen, Xiao-yao; Xue, Guo-hong; Zhu, Min-hao

    2018-03-01

    F6NM martensitic stainless steel was exposed to 350 °C water condition for 500, 1500, and 2500 h to simulate pressurized water reactor (PWR) condition. The characterization and corrosion behavior of the oxide film were investigated. Results indicate that the exposed steel surface formed a double-layer oxide film. The outer oxide film is Fe-rich and contains two type oxide particles. However, the inner oxide film is Cr-rich, and two oxide films, whose thicknesses increase with increasing exposure time. The oxide film reduces the corrosion behavior because the outer oxide film has many crack and pores. Finally, the mechanism and factors affecting the formation of the oxide film were investigated.

  12. Influence of high temperature on corrosion behavior of 304 stainless steel in chloride solutions

    Directory of Open Access Journals (Sweden)

    Saad R. Ahmed

    2016-11-01

    Full Text Available Despite the excellent performance of stainless steel in diverse application, there are media of exposure may accelerate failure of several stainless steel alloys. The possibility of this failure has to be examined by measuring the effective parameters that may result in corrosion at different rates. The present study has been conducted to examine the effect of exposing specimens of 304 stainless steel to 0.5, 1.0, 1.5 and 2.0 M chloride concentration and 70, 80, and 90 °C. Electrochemical technique of measuring the potentials and currency of the examined system has been used to collect the corrosion data. Microstructure of the specimens is examined using Scanning Electron Microscopy and X- Ray Diffraction. Both of these tests revealed no serious phase change due to exposure even at severe conditions. The potentials gained show significant effect of the operation conditions.

  13. Anti-corrosive Conversion Coating on Aluminium Alloys Using High Temperature Steam

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    and heterogeneity of native oxide layer does not provide long time corrosion resistance and adhesion of organic coating for a particular function in different environments. In order to enhance the corrosion resistance and adhesion of organic coating, the aluminium native oxide layer is treated to transform...... or convert to a functional conversion coating. In the last several decades chromate conversion coating (CrCCs) have been the most common conversion coatings used for aluminium alloys. Due to the toxicity of the hexavalent chrome, however, environmental friendly alternatives to CrCCs have been investigated...... extensively. Despite the intense research no equivalent substitute for (CrCCs) has been found. For these reasons, alternative conversion coatings are sought for substituting existing ones. Aluminium alloys AA 1090, Peraluman 706, and AA 6060 were subjected to high pressure steam treatment and various...

  14. Long-term stability and corrosion of high temperature alloys in HTR test helium

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, J.P.; Glaze, F.J.; Ali-Khan, I.

    1977-02-15

    Since the first test station was started up, about 60 long-time experiments have been completed within 2 years. Their running times lay between 100 and 9,000 hours. With these relatively short experimental times, the effect of strongly contaminated helium (simulation of the start-up phase of an HTR) on the long-time strength of the test materials could not be ascertained. Several results are graphically plotted. The micrographs below show several results from metallographic studies on long-time specimens in lengthwise section. The type and depth of corrosion attack by the HTR helium atmosphere varies considerably with the materials being studied. Specimens which were exposed to various helium contaminations in long-time test stations were subjected to metallographic study (KFA Juelich--CIIR Oslo). These studies showed that the corrosion behavior of the materials is more strongly influenced by the composition of the alloy than by the concentration of the helium contaminants.

  15. Corrosion of inconel in high-temperature borosilicate glass melts containing simulant nuclear waste

    Science.gov (United States)

    Mao, Xianhe; Yuan, Xiaoning; Brigden, Clive T.; Tao, Jun; Hyatt, Neil C.; Miekina, Michal

    2017-10-01

    The corrosion behaviors of Inconel 601 in the borosilicate glass (MW glass) containing 25 wt.% of simulant Magnox waste, and in ZnO, Mn2O3 and Fe2O3 modified Mg/Ca borosilicate glasses (MZMF and CZMF glasses) containing 15 wt.% of simulant POCO waste, were evaluated by dimensional changes, the formation of internal defects and changes in alloy composition near corrosion surfaces. In all three kinds of glass melts, Cr at the inconel surface forms a protective Cr2O3 scale between the metal surface and the glass, and alumina precipitates penetrate from the metal surface or formed in-situ. The corrosion depths of inconel 601 in MW waste glass melt are greater than those in the other two glass melts. In MW glass, the Cr2O3 layer between inconel and glass is fragmented because of the reaction between MgO and Cr2O3, which forms the crystal phase MgCr2O4. In MZMF and CZMF waste glasses the layers are continuous and a thin (Zn, Fe, Ni, B)-containing layer forms on the surface of the chromium oxide layer and prevents Cr2O3 from reacting with MgO or other constituents. MgCr2O4 was observed in the XRD analysis of the bulk MW waste glass after the corrosion test, and ZrSiO4 in the MZMF waste glass, and ZrSiO4 and CaMoO4 in the CZMF waste glass.

  16. 120 DEG C Cure, Durable, Corrosion Protection Powder Coatings for Temperature Sensitive Substrates

    Science.gov (United States)

    2005-01-28

    functional acrylics •Phenol functional resins Crosslinkers •Blocked isocyanates •Uretidiones Catalysts •Lewis Acids • Bismuth carboxylates •N,N...inhibitor, (1-benzothiazol-2-ylthio) succinic acid (Irgacor 252LD) were also tested. 72 Table 5.2 Eight corrosion...2-ylthio) Succinic Acid F Zinc Phosphate Zinc Phosphate G CW-491 Calcium Phosphosilicate H Test Substrates Chromated and untreated aluminum

  17. Radiolysis driven changes to oxide stability during irradiation-corrosion of 316L stainless steel in high temperature water

    Science.gov (United States)

    Raiman, Stephen S.; Bartels, David M.; Was, Gary S.

    2017-09-01

    316L stainless steel samples were irradiated with a proton beam while simultaneously exposed to high temperature water with hydrogen (320 °C, 3 wppm H2, neutral pH) to study the effect of radiation on corrosion. The inner oxides on irradiated samples were found to be depleted in chromium when compared to the inner oxides on unirradiated samples exposed to the same conditions. Additionally, hematite was found on the oxide surfaces of irradiated samples, but not on unirradiated samples. Sample areas which were not directly irradiated but were exposed to the flow of irradiated water also exhibited chromium-deficient inner oxides and had hematite on their surfaces, so it is concluded that water radiolysis is the primary driver of both effects. Thermodynamic calculations and radiolysis modeling were used to show that radiolytic production of hydrogen peroxide was sufficient to raise corrosion potential high enough to cause the dissolution of chromium-rich spinel oxides which make up the inner oxide layer on stainless steel in high temperature water.

  18. Low-temperature aqueous-phase methanol dehydrogenation to hydrogen and carbon dioxide.

    Science.gov (United States)

    Nielsen, Martin; Alberico, Elisabetta; Baumann, Wolfgang; Drexler, Hans-Joachim; Junge, Henrik; Gladiali, Serafino; Beller, Matthias

    2013-03-07

    Hydrogen produced from renewable resources is a promising potential source of clean energy. With the help of low-temperature proton-exchange membrane fuel cells, molecular hydrogen can be converted efficiently to produce electricity. The implementation of sustainable hydrogen production and subsequent hydrogen conversion to energy is called "hydrogen economy". Unfortunately, its physical properties make the transport and handling of hydrogen gas difficult. To overcome this, methanol can be used as a material for the storage of hydrogen, because it is a liquid at room temperature and contains 12.6 per cent hydrogen. However, the state-of-the-art method for the production of hydrogen from methanol (methanol reforming) is conducted at high temperatures (over 200 degrees Celsius) and high pressures (25-50 bar), which limits its potential applications. Here we describe an efficient low-temperature aqueous-phase methanol dehydrogenation process, which is facilitated by ruthenium complexes. Hydrogen generation by this method proceeds at 65-95 degrees Celsius and ambient pressure with excellent catalyst turnover frequencies (4,700 per hour) and turnover numbers (exceeding 350,000). This would make the delivery of hydrogen on mobile devices--and hence the use of methanol as a practical hydrogen carrier--feasible.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-03-31

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

  20. High temperature corrosion in biomass- and waste fired boilers. A status report; Kunskapslaeget betraeffande hoegtemperaturkorrosion i aangpannor foer biobraensle och avfall

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, P.; Ifwer, K.; Staalenheim, A.; Montgomery, M.; Hoegberg, J.; Hjoernhede, A.

    2006-12-15

    Many biomass- or waste-fired plants have problems with high temperature corrosion on the furnace walls or at the superheaters, especially if the steam temperature is greater than 500 deg C. An increase in the combustion of waste fuels means that an increasing number of boilers have had problems. Therefore, there is great interest from plant owners to reduce the costs associated with high temperature corrosion. At the same time there exists a considerable driving force towards improving the electrical efficiency of a plant by the use of more advanced steam data. The purpose of the work presented here was to answer three main questions: What can be done to reduce high temperature corrosion with current fuel blends and steam temperatures? How can more waste fuels be burnt without an increased risk for corrosion? What needs to be done to reach higher steam temperatures in the future? The level of knowledge of high temperature corrosion in biomass- and waste-fired boilers has been described and summarised. The following measures are recommended to reduce corrosion in existing plant: Make sure that the fuel is well mixed and improve fuel feeding to obtain a more even spread of the fuel over the cross-section of the boiler. Use combustion technology methods to stabilize the oxygen content of the flue gases near the membrane walls and other heat transfer surfaces. Experiment with additives and/or supplementary fuels which contain sulphur in some form, for example peat. Reduce the flue gas temperature at the superheaters. Review soot-blowing procedures or protect heat transfer surfaces from soot blowers. Evaluate coated membrane wall panels in parts of the furnace that experience the worst corrosion. Test more highly alloyed steels suitable for superheaters and when replacing a superheater change to a more highly alloyed steel. For the future, the following should be considered: The role of sulphur needs to be investigated more and other additives should be investigated

  1. Quantitative effect of temperature to the absorbance of aqueous glucose in wavelength range from 1200nm to 1700nm.

    Science.gov (United States)

    Cui, Houxin; An, Lin; Chen, Wenliang; Xu, Kexin

    2005-09-05

    In this paper, to find the quantitative errors of aqueous glucose induced by the temperature change at every wave point ranging from 1200nm to 1700nm, the calibration curve is calculated and shown. During the measurement the temperature varies from 30 degrees to 40 degrees , at a 2 degrees interval, and aqueous glucose concentration ranges from 100mg/dL to 500mg/dL, at a interval of 100mg/dL. The absorption of aqueous glucose decreases with the increasing of temperature, also the absorbance decreases. In addition, only 1 degrees change in the temperature induces about -7x10-3 and -4x10-3 errors in the absorbance of the aqueous glucose at the wavelength of 1550nm, 1610nm respectively. So the examined result should be correct according to the data read from the calibration curve if the temperatures of modeling and measuring are not uniform. Using this method, the error caused by the temperature change can be reduced even eliminated.

  2. Salting-out effects in aqueous ionic liquid solutions: cloud-point temperature shifts.

    Science.gov (United States)

    Trindade, Joana R; Visak, Zoran P; Blesic, Marijana; Marrucho, Isabel M; Coutinho, João A P; Lopes, José N Canongia; Rebelo, Luis P N

    2007-05-10

    The effects of the addition of three inorganic salts, namely, NaCl, Na(2)SO(4), and Na(3)PO(4), on the liquid-liquid (L-L) phase diagram of aqueous solutions containing the model ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF(4)], were investigated. All three inorganic salts trigger salting-out effects, leading to significant upward shifts of the L-L demixing temperatures of the systems. The magnitude of the shifts depends on both the water-structuring nature of the salt and its concentration; that is, the effects are correlated with the ionic strength of the solution and the Gibbs free energy of hydration of the inorganic salt. The pH effect and the occurrence of salt precipitation in concentrated solutions are also discussed.

  3. Shifts in the temperature of maximum density (TMD) of ionic liquid aqueous solutions.

    Science.gov (United States)

    Tariq, M; Esperança, J M S S; Soromenho, M R C; Rebelo, L P N; Lopes, J N Canongia

    2013-07-14

    This work investigates for the first time shifts in the temperature of maximum density (TMD) of water caused by ionic liquid solutes. A vast amount of high-precision volumetric data--more than 6000 equilibrated (static) high-precision density determination corresponding to ∼90 distinct ionic liquid aqueous solutions of 28 different types of ionic liquid--allowed us to analyze the TMD shifts for different homologous series or similar sets of ionic solutes and explain the overall effects in terms of hydrophobic, electrostatic and hydrogen-bonding contributions. The differences between the observed TMD shifts in the -2 liquids and are consistent with previous results that established hydrophobic and hydrophilic scales for ionic liquid ions based on their specific interactions with water and other probe molecules.

  4. Thermodynamic and transport properties of some biologically active compounds in aqueous solutions at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Dhondge, Sudhakar S., E-mail: s_dhondge@hotmail.co [P.G. Department of Chemistry, S.K. Porwal College, Kamptee, Nagpur 441 002 (India); Zodape, Sangesh P.; Parwate, Dilip V. [Department of Chemistry, R.T.M. Nagpur University, Nagpur 440 033 (India)

    2011-01-15

    The experimental data of density and viscosity have been obtained for aqueous solutions of biologically active compounds like salbutamol sulphate (SS), diethylcarbamazine citrate (DEC), and chlorpheniramine maleate (CPM) in the concentration range (0 to 0.15) mol . kg{sup -1} at three different temperatures. The derived parameters, such as apparent molar volume of solute ({phi}{sub V})), limiting apparent molar volume of solute ({phi}{sub V}{sup 0}), limiting apparent molar expansivity ({phi}{sub E}{sup 0}), thermal expansion coefficient ({alpha}*) and Jones-Dole equation viscosity A and B coefficients, were obtained using the density and viscosity results. It has been observed that the electrolyte-salt (SS) as well as adducts exhibit a positive viscosity B coefficient having negative ((dB)/(dT)). These results are interpreted in the light of possible solute-solute and solute-solvent interactions.

  5. High-temperature temporal stability of selected oxidizers as solids and in aqueous solutions. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Pellenbarg, R.E.; Smiroldo

    1986-08-08

    Various potential decontamination agents were examined as solids and in aqueous solutions for long-term stability at high temperatures. The following oxidizers were assayed iodometrically: the hypochlorite salts of calcium and lithium, sodium dischloroisocyanurate (PACE) and the preoxygen compounds sodium perborate, sodium peroxydisulfate, sodium percarbonate, and magnesium monoperoxyphthalate (H-48). The inorganic peroxide solids and the solid sodium dischloroisoyanurate were stable at 80 C, while the organic peroxide solids and the hypochlorite salts deteriorated markedly within 72 hours. In freshwater solutions of 0.01 N or less, the inorganic hypochlorite and peroxide salts decomposed slowly at 60 c. Conversely, the sodium dischloroisocyanurate, magnesium monoperoxyphthalate, and sodium percarbonate solutions exhibited near complete decomposition in 24 hours.

  6. The effect of zinc bath temperature on the morphology, texture and corrosion behaviour of industrially produced hot-dip galvanized coatings

    Directory of Open Access Journals (Sweden)

    A. Bakhtiari

    2014-03-01

    Full Text Available The purpose of this work is to identify the influence of zinc bath temperature on the morphology, texture and corrosion behavior of hot-dip galvanized coatings. Hot-dip galvanized samples were prepared at temperature in the range of 450-480 °C in steps of 10 °C, which is the conventional galvanizing temperature range in the galvanizing industries. The morphology of coatings was examined with optical microscopy and scanning electron microscopy (SEM. The composition of the coating layers was determined using energy dispersive spectroscopy (EDS analysis. The texture of the coatings was evaluated using X-ray diffraction. Corrosion behavior was performed using salt spray cabinet test and Tafel extrapolation test. From the experimental results, it was found that increasing the zinc bath temperature affects the morphology of the galvanized coatings provoking the appearance of cracks in the coating structure. These cracks prevent formation of a compact structure. In addition, it was concluded that (00.2 basal plane texture component was weakened by increasing the zinc bath temperature and, conversely, appearance of (10.1 prism component, (20.1 high angle pyramidal component and low angle component prevailed. Besides, coatings with strong (00.2 texture component and weaker (20.1 components have better corrosion resistance than the coatings with weak (00.2 and strong (20.1 texture components. Furthermore, corrosion resistance of the galvanized coatings was decreased by increasing the zinc bath temperature.

  7. phytochemicals as green corrosion inhibitors in various corrosive ...

    African Journals Online (AJOL)

    Mgina

    replace toxic inhibitors used for mitigation of corrosion of various metals and alloys in aqueous solutions. Plants represent a class of ... structures causing economic consequences in terms of repair, replacement, product ... Buchweishaija – Physicochemicals as green corrosion inhibitors … 78 rather complex molecular ...

  8. Phytochemicals as Green Corrosion Inhibitors in Various Corrosive ...

    African Journals Online (AJOL)

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

  9. Room-temperature aqueous plasma electrolyzing Al2O3 nano-coating on carbon fiber

    Science.gov (United States)

    Zhang, Yuping; Meng, Yang; Shen, Yonghua; Chen, Weiwei; Cheng, Huanwu; Wang, Lu

    2017-10-01

    A novel room-temperature aqueous plasma electrolysis technique has been developed in order to prepared Al2O3 nano-coating on each fiber within a carbon fiber bundle. The microstructure and formation mechanism of the Al2O3 nano-coating were systematically investigated. The oxidation resistance and tensile strength of the Al2O3-coated carbon fiber was measured at elevated temperatures. It showed that the dense Al2O3 nano-coating was relatively uniformly deposited with 80-120 nm in thickness. The Al2O3 nano-coating effectively protected the carbon fiber, evidenced by the slower oxidation rate and significant increase of the burn-out temperature from 800 °C to 950 °C. Although the bare carbon fiber remained ∼25 wt.% after oxidation at 700 °C for 20 min, a full destruction was observed, evidenced by the ∼0 GPa of the tensile strength, compared to ∼1.3 GPa of the Al2O3-coated carbon fiber due to the effective protection from the Al2O3 nano-coating. The formation mechanism of the Al2O3 nano-coating on carbon fiber was schematically established mainly based on the physic-chemical effect in the cathodic plasma arc zone.

  10. Anomalous dissolution of metals and chemical corrosion

    Directory of Open Access Journals (Sweden)

    DRAGUTIN M. DRAZIC

    2005-03-01

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

  11. Atomic Layer Deposited Coatings on Nanowires for High Temperature Water Corrosion Protection.

    Science.gov (United States)

    Yersak, Alexander S; Lewis, Ryan J; Liew, Li-Anne; Wen, Rongfu; Yang, Ronggui; Lee, Yung-Cheng

    2016-11-30

    Two-phase liquid-cooling technologies incorporating micro/nanostructured copper or silicon surfaces have been established as a promising thermal management solution to keep up with the increasing power demands of high power electronics. However, the reliability of nanometer-scale features of copper and silicon in these devices has not been well investigated. In this work, accelerated corrosion testing reveals that copper nanowires are not immune to corrosion in deaerated pure hot water. To solve this problem, we investigate atomic layer deposition (ALD) TiO 2 coatings grown at 150 and 175 °C. We measured no difference in coating thickness for a duration of 12 days. Using a core/shell approach, we grow ALD TiO 2 /Al 2 O 3 protective coatings on copper nanowires and demonstrate a preservation of nanoengineered copper features. These studies have identified a critical reliability problem of nanoscale copper and silicon surfaces in deaerated, pure, hot water and have successfully demonstrated a reliable solution using ALD TiO 2 /Al 2 O 3 protective coatings.

  12. Effects of temperature on stress corrosion cracking behavior of stainless steel and outer oxide distribution in cracks due to exposure to high-temperature water containing hydrogen peroxide

    Science.gov (United States)

    Nakano, Junichi; Sato, Tomonori; Kato, Chiaki; Yamamoto, Masahiro; Tsukada, Takashi; Kaji, Yoshiyuki

    2014-01-01

    Cracking growth tests were conducted in high-temperature water containing hydrogen peroxide (H2O2) at 561-423 K to evaluate the effects of H2O2 on stress corrosion cracking (SCC) of stainless steel (SS) at temperature lower than the boiling water reactor (BWR) operating temperature. Small compact tension (CT) specimens were prepared from thermally sensitized type 304 SS. Despite the observation of only a small portion intergranular SCC (IGSCC) near the side groove of the CT specimen at 561 K in high-temperature water containing 100 ppb H2O2, the IGSCC area expanded to the central region of the CT specimens at 423 and 453 K. Effects of H2O2 on SCC appeared intensely at temperature lower than the BWR operating temperature because of a reduction in the thermal decomposition of H2O2. To estimate the environment in the cracks, outer oxide distribution on the fracture surface and the fatigue pre-crack were examined by laser Raman spectroscopy and thermal equilibrium calculation was performed.

  13. Uptake of hypobromous acid (HOBr by aqueous sulfuric acid solutions: low-temperature solubility and reaction

    Directory of Open Access Journals (Sweden)

    L. T. Iraci

    2005-01-01

    Full Text Available Hypobromous acid (HOBr is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45-70wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201-252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H*=104-107mol L-1atm-1. H* is inversely dependent on temperature, with ΔH=-45.0±5.4 kJ mol-1 and ΔS=-101±24 J mol-1K-1 for 55-70wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into 55-70wt% H2SO4, the solubility is described by log H*=(2349±280/T-(5.27±1.24. At temperatures colder than ~213K, the solubility of HOBr in 45wt% H2SO4 is at least a factor of five larger than in 70wt% H2SO4, with log H*=(3665±270/T-(10.63±1.23. The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Upon uptake of HOBr into aqueous sulfuric acid in the presence of other brominated gases, particularly for 70wt% H2SO4 solution, our measurements demonstrate chemical reaction of HOBr followed by evolution of gaseous products including Br2O and Br2.

  14. Continuous flowing micro-reactor for aqueous reaction at temperature higher than 100 °C.

    Science.gov (United States)

    Xie, Fei; Wang, Baojun; Wang, Wei; Dong, Tian; Tong, Jianhua; Xia, Shanhong; Wu, Wengang; Li, Zhihong

    2013-01-01

    Some aqueous reactions in biological or chemical fields are accomplished at a high temperature. When the reaction temperature is higher than 100 °C, an autoclave reactor is usually required to elevate the boiling point of the water by creating a high-pressure environment in a closed system. This work presented an alternative continuous flowing microfluidic solution for aqueous reaction with a reaction temperature higher than 100 °C. The pressure regulating function was successfully fulfilled by a small microchannel based on a delicate hydrodynamic design. Combined with micro heater and temperature sensor that integrated in a single chip by utilizing silicon-based microfabrication techniques, this pressure regulating microchannel generated a high-pressure/high-temperature environment in the upstream reaction zone when the reagents continuously flow through the chip. As a preliminary demonstration, thermal digestion of aqueous total phosphorus sample was achieved in this continuous flowing micro-reactor at a working pressure of 990 kPa (under the working flow rate of 20 nl/s) along with a reaction temperature of 145 °C. This continuous flowing microfluidic solution for high-temperature reaction may find applications in various micro total analysis systems.

  15. Temperature of maximum density and excess thermodynamics of aqueous mixtures of methanol

    Energy Technology Data Exchange (ETDEWEB)

    González-Salgado, D.; Zemánková, K. [Departamento de Física Aplicada, Universidad de Vigo, Campus del Agua, Edificio Manuel Martínez-Risco, E-32004 Ourense (Spain); Noya, E. G.; Lomba, E. [Instituto de Química Física Rocasolano, CSIC, Calle Serrano 119, E-28006 Madrid (Spain)

    2016-05-14

    In this work, we present a study of representative excess thermodynamic properties of aqueous mixtures of methanol over the complete concentration range, based on extensive computer simulation calculations. In addition to test various existing united atom model potentials, we have developed a new force-field which accurately reproduces the excess thermodynamics of this system. Moreover, we have paid particular attention to the behavior of the temperature of maximum density (TMD) in dilute methanol mixtures. The presence of a temperature of maximum density is one of the essential anomalies exhibited by water. This anomalous behavior is modified in a non-monotonous fashion by the presence of fully miscible solutes that partly disrupt the hydrogen bond network of water, such as methanol (and other short chain alcohols). In order to obtain a better insight into the phenomenology of the changes in the TMD of water induced by small amounts of methanol, we have performed a new series of experimental measurements and computer simulations using various force fields. We observe that none of the force-fields tested capture the non-monotonous concentration dependence of the TMD for highly diluted methanol solutions.

  16. Platinum-modulated cobalt nanocatalysts for low-temperature aqueous-phase Fischer-Tropsch synthesis.

    Science.gov (United States)

    Wang, Hang; Zhou, Wu; Liu, Jin-Xun; Si, Rui; Sun, Geng; Zhong, Meng-Qi; Su, Hai-Yan; Zhao, Hua-Bo; Rodriguez, Jose A; Pennycook, Stephen J; Idrobo, Juan-Carlos; Li, Wei-Xue; Kou, Yuan; Ma, Ding

    2013-03-13

    Fischer-Tropsch synthesis (FTS) is an important catalytic process for liquid fuel generation, which converts coal/shale gas/biomass-derived syngas (a mixture of CO and H2) to oil. While FTS is thermodynamically favored at low temperature, it is desirable to develop a new catalytic system that could allow working at a relatively low reaction temperature. In this article, we present a one-step hydrogenation-reduction route for the synthesis of Pt-Co nanoparticles (NPs) which were found to be excellent catalysts for aqueous-phase FTS at 433 K. Coupling with atomic-resolution scanning transmission electron microscopy (STEM) and theoretical calculations, the outstanding activity is rationalized by the formation of Co overlayer structures on Pt NPs or Pt-Co alloy NPs. The improved energetics and kinetics from the change of the transition states imposed by the lattice mismatch between the two metals are concluded to be the key factors responsible for the dramatically improved FTS performance.

  17. Temperature and pH driven association in uranyl aqueous solutions

    Directory of Open Access Journals (Sweden)

    M. Druchok

    2012-12-01

    Full Text Available An association behavior of uranyl ions in aqueous solutions is explored. For this purpose a set of all-atom molecular dynamics simulations is performed. During the simulation, the fractions of uranyl ions involved in dimer and trimer formations were monitored. To accompany the fraction statistics one also collected distributions characterizing average times of the dimer and trimer associates. Two factors effecting the uranyl association were considered: temperature and pH. As one can expect, an increase of the temperature decreases an uranyl capability of forming the associates, thus lowering bound fractions/times and vice versa. The effect of pH was modeled by adding H+ or OH- ions to a "neutral" solution. The addition of hydroxide ions OH- favors the formation of the associates, thus increasing bound times and fractions. The extra H+ ions in a solution produce an opposite effect, thus lowering the uranyl association capability. We also made a structural analysis for all the observed associates to reveal the mutual orientation of the uranyl ions.

  18. Corrosion protection of Arctic offshore structures: Final report. [Effects of temperature and salinity on required cathodic protection current

    Energy Technology Data Exchange (ETDEWEB)

    Sackinger, W.M.; Rogers, J.C.; Feyk, C.; Theuveny, B.

    1985-10-01

    Results are presented for a research program on corrosion prevention for Arctic offshore structures which are in contact with sea ice for a significant portion of the year. The electrical method most adaptable for structure protection involves the injection of impressed current from several remote anodes buried just beneath the sea floor. The electrical resistivity of annual sea ice as a function of temperature and salinity is presented. Details of the interface layers formed between sea ice and steel in the presence of current injection are shown. A computer program was developed to enable the calculation of protective current density into the structure, in the presence of ice rubble and ridges around the structure. The program and the results of an example calculation are given for a caisson- retained island structure. 81 refs., 103 figs., 3 tabs.

  19. Corrosion testing of spent nuclear fuel performed at Argonne National Laboratory for repository acceptance

    Energy Technology Data Exchange (ETDEWEB)

    Goldberg, M. M.

    2000-07-20

    Corrosion tests of DOE-owned spent nuclear fuel are performed at Argonne National Laboratory to support the license application for the Yucca Mountain Repository. The tests are designed to determine corrosion rates and degradation products formed when fuel is reacted at elevated temperature in different aqueous environments, including vapor, dripping water, submersion, and liquid film contact. Corrosion rates are determined from the quantity of radionuclides released from wetted fuel and from the weight loss of the test fuel specimen as a function of time. Degradation products include secondary mineral phases and dissolved, adsorbed, and colloidal species. Solid phase examinations determine fuel/mineral interface relationships, characterize radionuclide incorporation into secondary phases, and determine corrosion mechanisms at grain interfaces within the fuel. Leachate solution analyses quantify released radionuclides and determine the size and charge distribution of colloids. This paper presents selected results from corrosion tests on metallic fuels.

  20. Temperature-induced aggregation in aqueous solutions of pluronic F68 triblock copolymer containing small amount of o-xylene

    DEFF Research Database (Denmark)

    Borbely, S.; Pedersen, J.S.

    2000-01-01

    The temperature- and concentration-dependent aggregation of EO(78)PO(30)EO(78) triblock copolymer in aqueous solutions has been studied in the concentration range from 5 to 200 g/dm(3) at 25 degrees C, 45 degrees C and 60 degrees C. The influence of o-xylene on the micellization was measured...

  1. Ambient temperature aqueous synthesis of ultrasmall copper doped ceria nanocrystals for the water gas shift and carbon monoxide oxidation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Curran, Christopher D. [Department of Chemical and Biomolecular Engineering; Lehigh University; Bethlehem; USA; Lu, Li [Department of Materials Science and Engineering; Lehigh University; Bethlehem; USA; Kiely, Christopher J. [Department of Chemical and Biomolecular Engineering; Lehigh University; Bethlehem; USA; Department of Materials Science and Engineering; McIntosh, Steven [Department of Chemical and Biomolecular Engineering; Lehigh University; Bethlehem; USA

    2018-01-01

    Ultra-small CuxCe1-xO2-δnanocrystals were prepared through a room temperature, aqueous synthesis method, achieving high copper doping and low water gas shift activation energy.

  2. Protein remains stable at unusually high temperatures when solvated in aqueous mixtures of amino acid based ionic liquids

    DEFF Research Database (Denmark)

    Chevrot, Guillaume; Fileti, Eudes Eterno; Chaban, Vitaly V.

    2016-01-01

    [EMIM][TRP] (5 mol% in water). Upon analyzing the radius of gyration, the solvent-accessible surface area, root-mean-squared deviations, and inter- and intramolecular hydrogen bonds, we found that the mini-protein remains stable at 30–40 K higher temperatures in aqueous amino acid based ionic liquids...

  3. Influence of preoxidation on high temperature corrosion of a Ni-based alloy under conditions relevant to biomass firing

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2017-01-01

    . Complementary characterization methods were employed to study samples after preoxidation as well as after corrosion exposure. The oxides obtained by the preoxidation treatments protected the alloy during corrosion exposure at 560 °C for a period of 168 h. In contrast, non-preoxidized samples suffered corrosion...... attack and formed porous non-protective oxides containing the alloying elements, Ni, Cr, Ti and Al. The influence of the preoxidation layers on the corrosion mechanism is discussed.......Development of corrosion resistant materials in biomass fired power plants demands specific attention since the condensation of deposits rich in KCl on heat exchanger surfaces induces severe corrosion attack, which is different from corrosion in traditional coal fired plants. Therefore, the ability...

  4. Pre-oxidation and its effect on reducing high-temperature corrosion of superheater tubes during biomass firing

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Kvisgaard, M.; Montgomery, Melanie

    2017-01-01

    Superheater tubes in biomass-fired power plants experience high corrosion rates due to condensation of corrosive alkali chloride-rich deposits. To explore the possibility of reducing the corrosion attack by the formation of an initial protective oxide layer, the corrosion resistance of pre......-oxidised Nimonic 80A remained unaffected suggesting protection of the alloy from the corrosive environment....... with a synthetic deposit of KCl and exposed at 560°C for 1 week to a gas mixture typical of biomass firing. Results show that pre-oxidation could hinder the corrosion attack; however, the relative success was different for the two alloys. While corrosion attack was observed on the pre-oxidised Kanthal APM, the pre...

  5. Influence of temperature on water and aqueous glucose absorption spectra in the near- and mid-infrared regions at physiologically relevant temperatures

    DEFF Research Database (Denmark)

    Jensen, P.S.; Bak, J.; Andersson-Engels, S.

    2003-01-01

    Near- and mid-infrared absorption spectra of pure water and aqueous 1.0 g/dL glucose solutions in the wavenumber range 8000-950 cm(-1) were measured in the temperature range 30-42 C in steps of 2 degreesC. Measurements were carried out with an FT-IR spectrometer and a variable pathlength transmis...

  6. Ocular surface temperature in patients with evaporative and aqueous-deficient dry eyes: a thermographic approach.

    Science.gov (United States)

    Matteoli, S; Favuzza, E; Mazzantini, L; Aragona, P; Cappelli, S; Corvi, A; Mencucci, R

    2017-07-26

    In recent decades infrared thermography (IRT) has facilitated accurate quantitative measurements of the ocular surface temperature (OST), applying a non-invasive procedure. The objective of this work was to develop a procedure based on IRT, which allows characterizing of the cooling of the ocular surface of patients suffering from dry eye syndrome, and distinguishing among patients suffering from aqueous deficient dry eye (ADDE) and evaporative dry eyes (EDE). All patients examined (34 females and 4 males, 23-84 years) were divided into two groups according to their Schirmer I result (⩽ 7 mm for ADDE and  >  7 mm for EDE), and the OST was recorded for 7 s at 30 Hz. For each acquisition, the temperatures of the central cornea (CC) as well as those of both temporal and nasal canthi were investigated. Findings showed that the maximum temperature variation (up to 0.75  ±  0.29 °C) was at the CC for both groups. Furthermore, patients suffering from EDE tended to have a higher initial OST than those with ADDE, explained by the greater quantity of the tear film, evenly distributed over the entire ocular surface, keeping the OST higher initially. Results also showed that EDE patients had an average cooling rate higher than those suffering from ADDE, confirming the excessive evaporation of the tear film. Ocular thermography paves the way to become an effective tool for differentiating between the two different etiologies of dry eye syndrome.

  7. Protection against corrosion to high temperature by means of rich silicon coatings; Proteccion contra corrosion a alta temperatura por medio de recubrimientos ricos en silicio

    Energy Technology Data Exchange (ETDEWEB)

    Porcayo Calderon, Jesus [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)

    1999-07-01

    In this research work the study of the process of corrosion by molten salts of sodium sulphate-vanadium pentoxide and its prevention by means of metallic coatings rich in silicon was contemplated. The research encompassed the development of the coating system, the chemical and thermochemical analysis of the system sodium sulphate - vanadium pentoxide, the evaluation of the resistance to the corrosion of the coating system by gravimetric and electrochemistry techniques, and the study of the stability of the coating system - substrate. [Spanish] En este trabajo de investigacion se contempla el estudio del proceso de corrosion por sales fundidas de sulfato de sodio - pentoxido de vanadio y su prevencion por medio de recubrimientos metalicos ricos en silicio. La investigacion abarca el desarrollo del sistema de recubrimientos, el analisis quimico y termoquimico del sistema sulfato de sodio - pentoxido de vanadio, la evaluacion de la resistencia a la corrosion del sistema de recubrimientos por tecnicas gravimetricas y electroquimicas, y el estudio de la estabilidad del sistema recubrimiento - sustrato.

  8. Survival of salmonella on dried fruits and in aqueous dried fruit homogenates as affected by temperature.

    Science.gov (United States)

    Beuchat, Larry R; Mann, David A

    2014-07-01

    A study was done to determine the ability of Salmonella to survive on dried cranberries, raisins, and strawberries and in date paste, as affected by storage temperature. Acid-adapted Salmonella, initially at 6.57 to 7.01 log CFU/g, was recovered from mist-inoculated cranberries (water activity [aw] 0.47) and raisins (aw 0.46) stored at 25°C for 21 days but not 42 days, strawberries (aw 0.21) for 42 days but not 84 days, and date paste (aw 0.69) for 84 days but not 126 days. In contrast, the pathogen was detected in strawberries stored at 4°C for 182 days (6 months) but not 242 days (8 months) and in cranberries, date paste, and raisins stored for 242 days. Surface-grown cells survived longer than broth-grown cells in date paste. The order of rate of inactivation at 4°C was cranberry > strawberry > raisin > date paste. Initially at 2.18 to 3.35 log CFU/g, inactivation of Salmonella on dry (sand)&ndash inoculated fruits followed trends similar to those for mist-inoculated fruits. Survival of Salmonella in aqueous homogenates of dried fruits as affected by fruit concentration and temperature was also studied. Growth was not observed in 10% (aw 0.995 to 0.999) and 50% (aw 0.955 to 0.962) homogenates of the four fruits held at 4°C, 50% homogenates at 25°C, and 10% cranberry and strawberry homogenates at 25°C. Growth of the pathogen in 10% date paste and raisin homogenates stored at 25°C was followed by rapid inactivation. Results of these studies suggest the need to subject dried fruits that may be contaminated with Salmonella to a lethal process and prevent postprocess contamination before they are eaten out-of-hand or used as ingredients in ready-to-eat foods. Observations showing that Salmonella can grow in aqueous homogenates of date paste and raisins emphasize the importance of minimizing contact of these fruits with high-moisture environments during handling and storage.

  9. Stable Inverted Low-Bandgap Polymer Solar Cells with Aqueous Solution Processed Low-Temperature ZnO Buffer Layers

    OpenAIRE

    Chunfu Zhang; Shangzheng Pang; Ting Heng; Hailong You; Genquan Han; Gang Lu; Fengqin He; Qubo Jiang; Jincheng Zhang

    2016-01-01

    Efficient inverted low-bandgap polymer solar cells with an aqueous solution processed low-temperature ZnO buffer layer have been investigated. The low-bandgap material PTB-7 is employed so that more solar light can be efficiently harvested, and the aqueous solution processed ZnO electron transport buffer layer is prepared at 150°C so that it can be compatible with the roll-to-roll process. Power conversion efficiency (PCE) of the inverted device reaches 7.12%, which is near the control conven...

  10. Size-selective synthesis of ultrasmall hydrophilic CdSe nanoparticles in aqueous solution at room temperature.

    Science.gov (United States)

    Park, Yeon-Su; Okamoto, Yukihiro; Kaji, Noritada; Tokeshi, Manabu; Baba, Yoshinobu

    2012-01-01

    Hydrophilic semiconductor nanoparticles are very attractive for various biological applications, such as in optical sensing, tracing, and imaging of biological molecules-of-interest, because of their broad excitation wavelength, tunable emission wavelength, strong photoluminescence, and relatively high stability against photobleaching and chemicals. Compared to organic phase synthesis and subsequent surface modification, aqueous phase synthesis approaches provide multiple advantages for obtaining hydrophilic semiconductor nanoparticles. Here, we describe methods for the size-selective growth and stabilization of ultrasmall hydrophilic CdSe nanoparticles in aqueous solution at room temperature by using amino acid cysteine or one of its derivatives as a surface capping agent.

  11. 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.

  12. Corrosion evaluation technology

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Uh Chul; Han, Jeong Ho; Nho, Kye Ho; Lee, Eun Hee; Kim, Hong Pyo; Hwang, Seong Sik; Lee, Deok Hyun; Hur, Do Haeng; Kim, Kyung Mo

    1997-09-01

    A multifrequency ACPD system was assembled which can measure very small crack. Stress corrosion cracking test system with SSRT operating high temperature was installed. Stress corrosion cracking test of newly developed alloy 600 and existing alloy 600 was carried out in steam atmosphere of 400 deg C. No crack was observed in both materials within a test period of 2,000 hrs. Corrosion fatigue test system operating at high temperature was installed in which fatigue crack was measured by CDPD. Lead enhanced the SCC of the Alloy 600 in high temperature water, had a tendency to modify a cracking morphology from intergranular to transgranular. Pit initiation preferentially occurred at Ti-rich carbide. Resistance to pit initiation decreased with increasing temperature up to 300 deg C. Test loop for erosion corrosion was designed and fabricated. Thin layer activation technique was very effective in measuring erosion corrosion. Erosion corrosion of a part of secondary side pipe was evaluated by the Check Family Codes of EPRI. Calculated values of pipe thickness by Check Family Codes coincided with the pipe thickness measured by UT with an error of {+-} 20%. Literature review on turbine failure showed that failure usually occurred in low pressure turbine rotor disc and causes of failure are stress corrosion cracking and corrosion fatigue. (author). 12 refs., 20 tabs., 77 figs.

  13. Computational Thermodynamic Modeling of Hot Corrosion of Alloys Haynes 242 and HastelloyTM N for Molten Salt Service in Advanced High Temperature Reactors

    Energy Technology Data Exchange (ETDEWEB)

    V. Glazoff, Michael; Charit, Indrajt; Sabharwall, Piyush

    2014-09-17

    An evaluation of thermodynamic aspects of hot corrosion of the superalloys Haynes 242 and HastelloyTM N in the eutectic mixtures of KF and ZrF4 is carried out for development of Advanced High Temperature Reactor (AHTR). This work models the behavior of several superalloys, potential candidates for the AHTR, using computational thermodynamics tool (ThermoCalc), leading to the development of thermodynamic description of the molten salt eutectic mixtures, and on that basis, mechanistic prediction of hot corrosion. The results from these studies indicated that the principal mechanism of hot corrosion was associated with chromium leaching for all of the superalloys described above. However, HastelloyTM N displayed the best hot corrosion performance. This was not surprising given it was developed originally to withstand the harsh conditions of molten salt environment. However, the results obtained in this study provided confidence in the employed methods of computational thermodynamics and could be further used for future alloy design efforts. Finally, several potential solutions to mitigate hot corrosion were proposed for further exploration, including coating development and controlled scaling of intermediate compounds in the KF-ZrF4 system.

  14. Aqueous geochemistry of low molecular weight hydrocarbons at elevated temperatures and pressures: constraints from mineral buffered laboratory experiments

    Science.gov (United States)

    Seewald, Jeffrey S.

    2001-05-01

    Organic matter, water, and minerals coexist at elevated temperatures and pressures in sedimentary basins and participate in a wide range of geochemical processes that includes the generation of oil and natural gas. A series of laboratory experiments were conducted at 300 to 350°C and 350 bars to examine chemical interactions involving low molecular weight aqueous hydrocarbons with water and Fe-bearing minerals under hydrothermal conditions. Mineral buffers composed of hematite-magnetite-pyrite, hematite-magnetite, and pyrite-pyrrhotite-magnetite were added to each experiment to fix the redox state of the fluid and the activity of reduced sulfur species. During each experiment the chemical system was externally modified by addition of ethene, ethane, propene, 1-butene, or n-heptane, and variations in the abundance of aqueous organic species were monitored as a function of time and temperature. Results of the experiments indicate that decomposition of aqueous n-alkanes proceeds through a series of oxidation and hydration reactions that sequentially produce alkenes, alcohols, ketones, and organic acids as reaction intermediaries. Organic acids subsequently undergo decarboxylation and/or oxidation reactions to form carbon dioxide and shorter chain saturated hydrocarbons. This alteration assemblage is compositionally distinct from that produced by thermal cracking under anhydrous conditions, indicating that the presence of water and minerals provide alternative reaction pathways for the decomposition of hydrocarbons. The rate of hydrocarbon oxidation decreases substantially under reducing conditions and in the absence of catalytically active aqueous sulfur species. These results represent compelling evidence that the stability of aqueous hydrocarbons at elevated temperatures in natural environments is not a simple function of time and temperature alone. Under the appropriate geochemical conditions, stepwise oxidation represents a mechanism for the decomposition of low

  15. Low temperature aqueous phase synthesis of silver/silver chloride plasmonic nanoparticles as visible light photocatalysts.

    Science.gov (United States)

    Song, Jooyoung; Roh, Jongmin; Lee, Inkyu; Jang, Jyongsik

    2013-10-14

    A one pot and environmentally benign synthetic route for plasmonic photocatalytic Ag@AgCl nanoparticles in a PVA-dissolved aqueous solution system is presented. The synthesized AgCl has a cubic-shape and its edge length can be controlled from ~57 to ~170 nm by varying the reaction temperature. In this system, PVA was used as a stabilizer for the formation of Ag@AgCl nanoparticles through interaction with Ag(+) ions. After partial reduction with l-arginine, the metallic Ag is formed on the surface of the AgCl substrates and the contents of the metallic Ag mainly affect both the visible-light absorption properties and the plasmonic photocatalytic efficiency of the Ag@AgCl nanocomposites. A plausible growth mechanism of metallic silver during the reduction process is proposed. More importantly, it is verified that the size of the AgCl substrate affected the light absorption region of the Ag@AgCl nanocomposite.

  16. Synthesis of transparent aqueous sols of colloidal layered niobate nanocrystals at room temperature.

    Science.gov (United States)

    Ban, Takayuki; Yoshikawa, Shogo; Ohya, Yutaka

    2011-12-01

    Transparent aqueous sols of colloidal tetramethylammonium niobate nanocrystals were synthesized by mixing tetramethylammonium hydroxide (TMAOH), niobium ethoxide, and water at TMAOH/Nb≥0.7 at room temperature. The X-ray diffraction patterns of the thin films prepared by evaporating the colloidal solutions on a glass substrate indicated that the colloidal niobate had a layered crystalline structure. Two types of layered structures are known as a layered niobate, i.e. M(4)Nb(6)O(17)·nH(2)O and MNb(3)O(8) (M=H, H(3)O, or alkaline metal). Raman spectra and electron diffraction suggested that the niobate nanocrystals were similar in crystal structure to M(4)Nb(6)O(17)·nH(2)O compounds. Moreover, when niobium oxide thin films were fabricated from the niobate colloidal solutions by the sol-gel method, oriented T-Nb(2)O(5) thin films, whose c-axis was parallel to the substrate surface, were obtained. The orientation of the thin films was probably attributed to the layered structure of the colloidal niobate nanocrystals. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. High temperature corrosion of hot-dip aluminized steel in Ar/1%SO2 gas

    Science.gov (United States)

    Abro, Muhammad Ali; Lee, Dong Bok

    2017-01-01

    Carbon steels were hot-dip aluminized in Al or Al-1at%Si baths, and corroded in Ar/1%SO2 gas at 700-800 °C for up to 50 h. The aluminized layers consisted of not only an outer Al(Fe) topcoat that had interdispersed needle-like Al3Fe particles but also an inner Al-Fe alloy layer that consisted of an outer Al3Fe layer and an inner Al5Fe2 layer. The Si addition in the bath made the Al(Fe) topcoat thin and nonuniform, smoothened the tongue-like interface between the Al-Fe alloy layer and the substrate, and increased the microhardness of the aluminized layer. The aluminized steels exhibited good corrosion resistance by forming thin α-Al2O3 scales, along with a minor amount of iron oxides on the surface. The interdiffusion that occurred during heating made the aluminized layer thick and diffuse, resulting in the formation of Al5Fe2, AlFe and AlFe3 layers. It also smoothened the tongue-like interface, and decreased the microhardness of the aluminized layer. The non-aluminized steel formed thick, nonadherent, nonprotective (Fe3O4, FeS)-mixed scales.

  18. THERMODYNAMICS OF LOW-TEMPERATURE (700-850{degree}C) HOT CORROSION

    Energy Technology Data Exchange (ETDEWEB)

    Misra, A. K.; Whittle, D. P.; Worrell, W. L.

    1980-09-01

    Existing phase diagrams in the systems Na{sub 2}SO{sub 4} - MSO}{sub 4} (M=Ni, Co) and Na{sub 2}SO{sub 4} - M{sub 2}(SO{sub 4}){sub 3} (M=Al, Fe, Cr) have been used to calculate the thermodynamic properties of the molten sulfate systems. The calculated thermodynamic data show satisfactory agreement with most of the available experimental observations. The calculations have shown that the activity of Al{sub 2}(SO{sub 4}){sub 3} and Fe{sub 2}(SO{sub 4}){sub 3} in the melt can be lowered to such an extent that liquid sulfate solutions can be formed at P{sub SO{sub 3}} levels that are prevalent in marine gas turbine operations, and this has been explained on the basis of complex formation in the melt. Thermodynamic analysis of the interaction of the Na{sub 2}SO{sub 4} - MSO{sub 4} (M=Co, Ni) melt with protective oxides Al{sub 2}O{sub 3} and Cr{sub 2}O{sub 3} has demonstrated the vulnerability of Al-containing alloys to hot corrosion attack.

  19. Microstructural investigations of pure nickel exposed to KCl induced high temperature corrosion

    DEFF Research Database (Denmark)

    Jonsson, T.; Slomian, A.; Lomholt, Trine Nybo

    2015-01-01

    Oxidation of 99?99% pure nickel was studied with and without 0?10 mg cm22 KCl(s) in an environment containing 5 vol.-%O2, 40 vol.-%H2O and 55 vol.-%N2 at 600uC for up to 168 h. Oxide microstructure was investigated by X-ray diffraction (XRD), focused ion beam (FIB), broad ion beam (BIB) and SEM....../EDX. Oxidised nickel shows an approximately parabolic oxide growth rate. The oxide scale is dense with some pores at the oxide/metal interface. Adding small amounts of KCl does not result in a faster corrosion rate of nickel. However, the surface morphology changes and small oxide crusts were observed...... in the vicinity of former KCl particles. This is proposed to be the result of a NiCl2–KCl eutectic on top of the oxide scale formed above 514uC. The oxide scale formed in the presence of KCl contains more and differently distributed voids than the scale formed without KCl....

  20. Effects of aging temperature and time on the corrosion protection provided by trivalent chromium process coatings on AA2024-T3.

    Science.gov (United States)

    Li, Liangliang; Swain, Greg M

    2013-08-28

    The effects of aging temperature and time on the physical structure of and corrosion protection provided by trivalent chromium process (TCP) coatings on AA2024-T3 are reported. The TCP coating forms a partially blocking barrier layer on the alloy surface that consists of hydrated channels and or defects. It is through these channels and defects that ions and dissolved O2 can be transported to small areas of the underlying alloy. Reactions initiate at these sites, which can ultimately lead to undercutting of the coating and localized corrosion. We tested the hypothesis that collapsing the channels and or reducing the number of defects in the coating might be possible through post-deposition heat treatment, and that this would enhance the corrosion protection provided by the coating. This was tested by aging the TCP-coated AA2024 alloys in air overnight at room temperature (RT), 55, 100, or 150 °C. The TCP coating became dehydrated and thinner at the high temperatures (55 and 100 °C). This improved the corrosion protection as evidenced by a 2× increase in the charge transfer resistance. Aging at 150 °C caused excessive coating dehydration and shrinkage. This led to severe cracking and detachment of the coating from the surface. The TCP-coated AA2024 samples were also aged in air at RT from 1 to 7 days. There was no thinning of the coating, but the corrosion protection was enhanced with a longer aging period as evidenced by a 4× increase in the charge transfer resistance. The coating became more hydrophobic after aging at elevated temperature (up to 100 °C) and with aging time at RT as evidenced by an increased water contact angle from 7 to 100 °C.

  1. corrosion of a carbon steel covered by treated bentonites in ...

    African Journals Online (AJOL)

    F. Arbaoui

    2017-09-01

    clay/aqueous solutions study. Two Algerian bentonites have been considered. The obtained results show that both clays are corrosive even in the absence of chloride ions. We show that this corrosiveness is related to the ...

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

    Science.gov (United States)

    Mehmeti, Valbonë V; Berisha, Avni R

    2017-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Valbonë V. Mehmeti

    2017-08-01

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

  4. 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

  5. Arrhenius-Type Constitutive Model for High Temperature Flow Stress in a Nickel-Based Corrosion-Resistant Alloy

    Science.gov (United States)

    Wang, L.; Liu, F.; Cheng, J. J.; Zuo, Q.; Chen, C. F.

    2016-04-01

    Hot deformation behavior of Nickel-based corrosion-resistant alloy (N08028) was studied in compression tests conducted in the temperature range of 1050-1200 °C and the strain rate range of 0.001-1 s-1. The flow stress behavior and microstructural evolution were observed during the hot deformation process. The results show that the flow stress increases with deformation temperature decreasing and strain rate increasing, and that the deformation activation energy ( Q) is not a constant but increases with strain rate increasing at a given strain, which is closely related with dislocation movement. On this basis, a revised strain-dependent hyperbolic sine constitutive model was established, which considered that the "material constants" in the original model vary as functions of the strain and strain rate. The flow curves of N08028 alloy predicted by the proposed model are in good agreement with the experimental results, which indicates that the revised constitutive model can estimate precisely the flow curves of N08028 alloy.

  6. Mathematical modeling of the temperature effect on the character of linking between monomeric proteins in aqueous solutions

    Science.gov (United States)

    Koshlan, T. V.; Kulikov, K. G.

    2017-11-01

    This work is devoted to the mathematical modeling of the temperature effect on the stability of H2A-H2B and H3-H4 histone dimers by studying their behavior in different temperature regimes of 20-50°C. The study of the thermal stability of these two dimers in aqueous solutions at different temperatures has revealed their multifarious behavior at temperatures at 20-50°C. Analysis has shown that dimer H3-H4 is prone to aggregation due to an increase in the force of linking between histones H3 and H4. Studies of the behavior of histone dimer H2A-H2B have disclosed different temperature transitions in its structure with a maximum peak at a temperature 45°C.

  7. Iron-niobium-aluminum alloy having high-temperature corrosion resistance

    Science.gov (United States)

    Hsu, Huey S.

    1988-04-14

    An alloy for use in high temperature sulfur and oxygen containing environments, having aluminum for oxygen resistance, niobium for sulfur resistance and the balance iron, is discussed. 4 figs., 2 tabs.

  8. Effect of Surface Pretreatment on the Underpaint Corrosion of AA2024-T3 at Various Temperatures

    National Research Council Canada - National Science Library

    Little, D. A; Jakab, M. A; Scully, J. R

    2006-01-01

    .... The scribe-creep rate was accelerated at all temperatures especially by pretreatments that increased the concentration of surface Cu or left a high capacity for Cu-replating. Sodium hydroxide (NaOH...

  9. Corrosion and Creep of Candidate Alloys in High Temperature Helium and Steam Environments for the NGNP

    Energy Technology Data Exchange (ETDEWEB)

    Was, Gary; Jones, J. W.

    2013-06-21

    This project aims to understand the processes by which candidate materials degrade in He and supercritical water/steam environments characteristic of the current NGNP design. We will focus on understanding the roles of temperature, and carbon and oxygen potential in the 750-850 degree C range on both uniform oxidation and selective internal oxidation along grain boundaries in alloys 617 and 800H in supercritical water in the temperature range 500-600 degree C; and examining the application of static and cyclic stresses in combination with impure He environments in the temperature rang 750-850 degree C; and examining the application of static and cyclic stresses in combination with impure He environments in the temperature range 750-850 degree C over a range of oxygen and carbon potentials in helium. Combined, these studies wil elucidate the potential high damage rate processes in environments and alloys relevant to the NGNP.

  10. Complexity of Products of Tungsten Corrosion: Comparison of the 3D Pourbaix Diagrams with the Experimental Data

    Science.gov (United States)

    Nave, Maryana I.; Kornev, Konstantin G.

    2017-03-01

    Tungsten is one of the most attractive metals in applications where materials are subject to high temperature and strong fields. However, in harsh aqueous environment, tungsten is prone to corrosion. Control of tungsten corrosion in aqueous solutions is a challenging task: as a transition metal, tungsten is able to produce a vast variety of oxides and hydrates. To reveal the thermodynamic pathway of corrosion at different conditions, the 3D Pourbaix diagrams relating the reduction potential, pH, and concentration of different tungsten-based compounds were constructed. These diagrams allow one to identify the most thermodynamically stable tungsten-based compounds. The 3D Pourbaix diagrams were used to explain different regimes of anodic dissolution of tungsten in aqueous solutions of potassium hydroxide.

  11. Gaining new insight into low-temperature aqueous photochemical solution deposited ferroelectric PbTiO{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    De Dobbelaere, Christopher, E-mail: christopher.dedobbelaere@uhasselt.be [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, B-3500, Hasselt (Belgium); Calzada, M. Lourdes; Bretos, Iñigo; Jiménez, Ricardo; Ricote, Jesús [Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Cantoblanco, E-28049, Madrid (Spain); Hadermann, Joke [University of Antwerp, Department of Physics, EMAT, B-2020, Antwerp (Belgium); Hardy, An [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, B-3500, Hasselt (Belgium); IMEC vzw, Division IMOMEC, B-3590, Diepenbeek (Belgium); Van Bael, Marlies K., E-mail: marlies.vanbael@uhasselt.be [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, B-3500, Hasselt (Belgium); IMEC vzw, Division IMOMEC, B-3590, Diepenbeek (Belgium)

    2016-05-01

    The nature of the low-temperature photochemical assisted formation process of ferroelectric lead titanate (PbTiO{sub 3}) films is studied in the present work. Films are obtained by the deposition of an aqueous solution containing citric acid based (citrato) metal ion complexes with intrinsic UV activity. This UV activity is crucial for the aqueous photochemical solution deposition (aqueous PCSD) route being used. UV irradiation enhances the early decomposition of organics and results in improved electrical properties for the crystalline oxide film, even if the film is crystallized at low temperature. GATR-FTIR shows that UV irradiation promotes the decomposition of organic precursor components, resulting in homogeneous films if applied in the right temperature window during film processing. The organic content, morphology and crystallinity of the irradiated films, achieved at different processing atmospheres and temperatures, is studied and eventually correlated to the functional behavior of the obtained films. This is an important issue, as crystalline films obtained at low temperatures often lack ferroelectric responses. In this work, the film prepared in pure oxygen at the very low temperature of 400 °C and after an optimized UV treatment presents a significant remanent polarization value of P{sub r} = 8.8 μC cm{sup −2}. This value is attributed to the better crystallinity, the larger grain size and the reduced porosity obtained thanks to the early film crystallization effectively achieved through the UV treatment in oxygen. - Highlights: • Precursor chemistry enables the UV assisted film deposition process. • PbTiO3 films with improved ferroelectric response and crystallinity are obtained. • UV active components are formed during the whole film formation process. • Perovskite, ferroelectric active PbTiO3 films are formed at 400 °C. • Oxide films can be prepared at reduced temperature.

  12. Effect of temperature and time on zinc borate species formed from zinc oxide and boric acid in aqueous medium

    OpenAIRE

    Eltepe, H. Emre; Balköse, Devrim; Ülkü, Semra

    2007-01-01

    The effect of temperature and time of heating of zinc oxide and boric acid in aqueous medium on product type, dehydration behavior, crystal morphology, and structure was investigated for the production of flame retardant and smoke suppressant zinc borate. Two different products dehydrated at 140 and 350°C were obtained and characterized by thermal gravimetric analysis, X-ray diffraction, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy.

  13. Low-temperature liquid-liquid extraction of phenols from aqueous solutions with hydrophilic mixtures of extractants

    Science.gov (United States)

    Rudakov, O. B.; Khorokhordina, E. A.; Preobrazhenskii, M. A.; Rudakova, L. V.

    2016-08-01

    The volume ratios in acetonitrile-ethyl acetate (90 : 10, 95 : 5), acetonitrile-isopropanol-ethyl acetate (70 : 15 : 15, 80 : 5 : 15), and isopropanol-1-butanol (50 : 50) mixtures were determined. Their mixing with water (1 : 1) and storage at-10°C led to partitioning into two immiscible liquid phases without formation of the ice phase. The mixtures were shown to be useful as hydrophilic extractants in low-temperature liquidliquid extraction of phenol from aqueous solutions.

  14. Corrosion reliability of electronics: the influence of solder temperature on the decomposition of flux activators

    DEFF Research Database (Denmark)

    Piotrowska, Kamila; Conseil, Helene; Jellesen, Morten Stendahl

    2014-01-01

    This manuscript gives a brief overview on the studies of thermal decomposition of solder flux systems commonly used in the electronic industry. Changes in chemical composition and structural changes of the flux components have been investigated as a function of temperature. Six weak organic acids...

  15. In-situ localized corrosion behavior of SiCp/Al composites in 3.5% NaCl aqueous solution

    Science.gov (United States)

    Cui, Xia; Zhou, Xianliang; Ouyang, Delai; Ye, Zhiguo; Zhu, Min

    2018-01-01

    The localized corrosion behaviors of SiCp/Al composites in 3.5% NaCl solution were in-situ investigated by the scanning micro-reference electrode technique. The results show that pitting is a predominant corrosion mechanism in these composites. Hydrolysis of Al4C3 at the interface of the composites is responsible for the first stage of the pitting attack. It was found that metastable pits were re-passivated by the corrosion products of Al(OH)2Cl and Al(OH)Cl2, and the propagation of metastable pits is related to the formation of AlCl3. In addition, a pitting mechanism for the composites is proposed.

  16. Control of temperature and aqueous Mg2+/Ca2+ ratio on the (trans-)formation of ikaite

    Science.gov (United States)

    Purgstaller, B.; Dietzel, M.; Baldermann, A.; Mavromatis, V.

    2017-11-01

    The calcium carbonate hexahydrate mineral ikaite (CaCO3 ṡ 6 H2O) has been documented in aquatic environments at near-freezing temperatures. An increase of the prevailing temperature in the depositional environment, results in the transformation of natural ikaite into less soluble calcium carbonate phases occasionally leaving calcite pseudomorphs in the sediments, which are considered as an indicator for primary cold water temperatures. Detailed understanding on the physicochemical parameters controlling ikaite (trans-)formation however, such as temperature and reactive solution chemical composition, are still under debate. In order to study the formation of ikaite, we conducted precipitation experiments under controlled physicochemical conditions (pH = 8.3 ± 0.1; T = 6, 12, and 18 ± 0.1 °C) at defined aqueous molar Mg/Ca ratios. The transformation of ikaite into anhydrous calcium carbonate polymorphs was investigated in solution and at air exposure. The obtained results reveal the formation of ikaite at temperatures up to 12 °C, whereas Mg-rich amorphous calcium carbonate precipitated at 18 °C. In contact with the reactive solution ikaite transformed into aragonite at aqueous molar Mg2+/Ca2+ ratios of ≥14. In contrast, ikaite separated from the Mg-rich solution and exposed to air transformed in all cases into calcite/vaterite. The herein obtained temperature limit of ≤12 for ikaite formation is significantly higher than formerly expected and most probably caused by (i) the high saturation degree of the solution with respect to ikaite and (ii) the slow dehydration of the aqueous Ca2+ ion at low temperatures. This result questions the suitability of calcite pseudomorphs (i.e. glendonites) as a proxy for near-freezing temperatures. Moreover, our findings show that the CaCO3 polymorph formed from ikaite is strongly controlled by the physicochemical conditions, such as aqueous molar Mg2+/Ca2+ ratio of the reactive fluid and H2O availability throughout the

  17. The Conductivity of Aqueous K2CO3 at Elevated Temperatures and Pressures, Measured using the AC van der Pauw Technique

    DEFF Research Database (Denmark)

    Mollerup, Pia Lolk; Christiansen, Ane Sælland; Bonanos, Nikolaos

    2013-01-01

    Conductivity measurements of aqueous K2CO3 were performed using the van der Pauw method and a specially designed sample holder with Pt wires as electrodes. The resistance was measured using alternating current. The conductivity of 10-50 wt% aqueous K2CO3 was measured at room temperature and ambie...

  18. Densities of L-Glutamic Acid HCl Drug in Aqueous NaCl and KCl Solutions at Different Temperatures

    Science.gov (United States)

    Ryshetti, Suresh; Raghuram, Noothi; Rani, Emmadi Jayanthi; Tangeda, Savitha Jyostna

    2016-04-01

    Densities (ρ ) of (0.01 to 0.07) {mol}{\\cdot } {kg}^{-1} L-Glutamic acid HCl (L-HCl) drug in water, and in aqueous NaCl and KCl (0.5 and 1.0) {mol}{\\cdot } {kg}^{-1} solutions have been reported as a function of temperature at T = (298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure. The accurate density (ρ ) values are used to estimate the various parameters such as the apparent molar volume (V_{2,{\\upphi }}), the partial molar volume (V2^{∞}), the isobaric thermal expansion coefficient (α 2), the partial molar expansion (E2^{∞}), and Hepler's constant (partial 2V2^{∞}/partial T2)P. The Cosphere overlap model is used to understand the solute-solvent interactions in a ternary mixture (L-HCl drug + NaCl or KCl + water). Hepler's constant (partial 2V2^{∞}/partial T2)_P is utilized to interpret the structure-making or -breaking ability of L-HCl drug in aqueous NaCl and KCl solutions, and the results are inferred that L-HCl drug acts as a structure maker, i.e., kosmotrope in aqueous NaCl solutions and performs as a structure breaker, i.e., chaotrope in aqueous KCl solutions.

  19. High temperature corrosion of cast irons and cast steels in dry air

    Energy Technology Data Exchange (ETDEWEB)

    Tholence, F.; Norell, M. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Engineering Metals

    2001-07-01

    The oxidation in dry air of four cast alloys intended for exhaust gas systems has been examined. Particular interest was directed to how the oxide growth was related to the microstructures. The examined alloys were two cast ductile irons, a SiMo alloy (Fe3,86Si0,6Mo3C) and a Ni-Resist alloy (Fe32Ni5,3Si2,1C), and two cast stainless steels, one ferritic (Fe18Cr2,1Mn0,32C) and one austenitic (Fe20Cr9Ni0,47C). Coupons were oxidised for 50 h at temperatures between 650 C and 1050 C. The samples were characterised by using XRD, SEM/EDX and AES. As expected, the overall oxide thickness increased with temperature and partial spallation occurred at the highest temperatures for all alloys. Porous Fe oxide nodules nucleate at the graphite nodules on the ductile irons. These Fe-oxide nodules formed above a continuous layer of Fe-Si-oxide for the SiMo and mixed Fe-Ni-Si oxides for the Ni-Resist. The total oxide thickness is about (60 {mu}m). Thick oxides at the interdendritic regions in the cast steels were attributed to non-Cr-carbides. Segregation of Cr directed the formation of iron oxide nodules to the centre of the dendrites in the austenitic alloy. (orig.)

  20. Accelerated corrosion and oxide dissolution in 316L stainless steel irradiated in situ in high temperature water

    Science.gov (United States)

    Raiman, Stephen S.; Was, Gary S.

    2017-09-01

    316L stainless steel samples were irradiated with a proton beam while simultaneously exposed to high temperature water with added hydrogen (320 °C, 3 wppm H2, neutral pH) to study the effect of radiation on stainless steel corrosion. Irradiated samples had thinner and more porous inner oxides with a lower chromium content when compared to unirradiated samples. Observations suggest that depletion of chromium from the inner oxide can be attributed to the dissolution of chromium-rich spinel oxides in irradiated water, leading to an accelerated rate of inner oxide dissolution. Sample areas which were not irradiated, but were exposed to the flow of irradiated water were also found to be porous and deficient in chromium, indicating that these phenomena can be attributed primarily to water radiolysis. A new empirical equation for oxide growth and dissolution is used to describe the observed changes in oxide thickness under irradiation. An experiment in which a stainless steel sample was exposed to high temperature water (320 °C, 3 wppm H2, neutral pH) without irradiation, and then exposed for a second time with irradiation was conducted to observe the effect of irradiation on a pre-formed protective film. After the irradiated exposure, the sample exhibited chromium loss in regions which were directly irradiated, but not on regions exposed only to irradiated water, suggesting that a pre-formed protective oxide may be effective in preventing chromium loss due to irradiated water. Additionally, this observation suggests that enhanced kinetics under irradiation may have accelerated dissolution of chromium from the inner oxide.

  1. Relations between combustion, deposition, flue gas temperatures and corrosion in straw-fired boilers

    DEFF Research Database (Denmark)

    Montgomery, Melanie

    2004-01-01

    using an aluminium silicate additive, however the relative chlorine content of the deposits was unchanged. At Ensted woodchip plant, a dosage level of additives was reached which reduced the chlorine flux. For straw firing where the chlorine level in the fuel is higher and the fuel load is greater......, the chlorine flux on deposition probes was not affected by additive dosage. An indication that some chlorine had been removed could be measured by the increased HCl output during additive dosage. The importance of temperature and where the additive is dosed is discussed....

  2. Physical and Chemical Stability of Curcumin in Aqueous Solutions and Emulsions: Impact of pH, Temperature, and Molecular Environment.

    Science.gov (United States)

    Kharat, Mahesh; Du, Zheyuan; Zhang, Guodong; McClements, David Julian

    2017-03-01

    The utilization of curcumin as a nutraceutical in food and supplement products is often limited because of its low water solubility, poor chemical stability, and low oral bioavailability. This study examined the impact of pH, storage temperature, and molecular environment on the physical and chemical stability of pure curcumin in aqueous solutions and in oil-in-water emulsions. Unlike naturally occurring curcuminoid mixtures (that contain curcumin, demethoxy-curcumin, and bisdemethoxy-curcumin), pure curcumin was highly unstable to chemical degradation in alkaline aqueous solutions (pH ≥7.0) and tended to crystallize out of aqueous acidic solutions (pH emulsions (30% MCT, 1 mg curcumin/g MCT, d 32 ≈ 298 nm) improved its water dispersibility and chemical stability. After incubation at 37 °C for 1 month, >85% of curcumin was retained by emulsions stored under acidic conditions (pH emulsions stored at pH 7.0, 7.4, and 8.0, respectively. There was little change in the color of curcumin-loaded emulsions when stored under acidic conditions, but their yellow color faded when stored under alkaline conditions. There was no evidence of droplet aggregation or creaming in emulsions stored for 31 days at ambient temperature. These results suggest that emulsion-based delivery systems may be suitable for improving the water dispersibility and chemical stability of curcumin, which would facilitate its application in foods and supplements.

  3. Effects of hardness and test temperature on the stress-corrosion cracking susceptibility of carbon steel in simulated BWR environment; Koon koatsu sui kankyo ni okeru tansoko no oryoku fushokuware kanjusei ni oyobosu kodo, oyobi shiken ondo no eikyo hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, G.; Akashi, M. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

    1998-03-15

    An SSRT test and a CBB test were carried out on carbon steel and heat treated materials applied with bead welding of single pass simulating fillet welding in oxygen-enriched high-temperature water environment, and the stress-corrosion cracking susceptibility was evaluated. Highly hard welding heat affected zones with Vickers hardness of more than 400 have grain boundary stress-corrosion cracking susceptibility. However, a structure whose high hardness has been realized by tempering treatment has no grain boundary stress-corrosion cracking susceptibility. In the SSRT test, stress-corrosion cracking fractured face rate rises with rising test temperature, resulting in stress-corrosion cracking susceptibility shown even at lower hardness. On the other hand in the CBB test, a large number of relatively shallow cracks are generated down to low hardness at temperatures below 190 degC, while the number of cracking occurrence decreases as the temperature rises. However, deep cracks increase. In the CBB test on tempered heat treatment materials, the fact that stress-corrosion cracking can occur in test pieces with Vickers hardness of 165, which is nearly the same as that for the base material, proves that no lower limit hardness exists practically in occurrence of stress-corrosion cracking in carbon steel. 13 refs., 12 figs., 2 tabs.

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

    OpenAIRE

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

    2011-01-01

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

  5. The effect of organic matter associated with the corrosion products on the corrosion of mild steel in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Wagh, A.B.

    the corrosion of mild steel and the temperature and dissolved oxygen of seawater. In contrast to this, the corrosion and mild steel was inversely related to the organic carbon and water extractable carbohydrates associated with the corrosion products of mild...

  6. Stable Inverted Low-Bandgap Polymer Solar Cells with Aqueous Solution Processed Low-Temperature ZnO Buffer Layers

    Directory of Open Access Journals (Sweden)

    Chunfu Zhang

    2016-01-01

    Full Text Available Efficient inverted low-bandgap polymer solar cells with an aqueous solution processed low-temperature ZnO buffer layer have been investigated. The low-bandgap material PTB-7 is employed so that more solar light can be efficiently harvested, and the aqueous solution processed ZnO electron transport buffer layer is prepared at 150°C so that it can be compatible with the roll-to-roll process. Power conversion efficiency (PCE of the inverted device reaches 7.12%, which is near the control conventional device. More importantly, the inverted device shows a better stability, keeping more than 90% of its original PCE after being stored for 625 hours, while PCE of the conventional device is only 75% of what it was. In addition, it is found that the ZnO thin film annealed in N2 can obviously increase PCE of the inverted device further to 7.26%.

  7. High-temperature oxidation/corrosion of iron-based superalloys

    Science.gov (United States)

    Lemkey, F. D.; Smeggil, J. G.; Bailey, R. S.; Schuster, J. C.; Nowotny, H.

    1987-01-01

    The oxidation and sulfidation of several novel iron-base superalloys were evaluated in high-temperature cyclic tests. The experimental austenitic alloys examined were modifications of NASAUT-4GA which were developed for Stirling-engine application. The weight gains and resulting surface scales were measured and analyzed. Mixed oxide scales were found to form on all specimens exposed above 871 C. The build-up of these scales led to a depletion of Mn and Cr in a zone adjacent to the oxides. In addition, the initial oxidation of the Fe-rich alloy was inhibited by a thin but tenacious Si layer which formed at the interface between oxides and the parent layer. Sulfidation tests using Na2SO4 coatings resulted in the formation of a protective spinel and alpha-Fe2O3 phases. Preferential attack of the carbide phase by hydrogen was not observed after 350 h at 871 C.

  8. Effects of temperature on the corrosion behavior of coated carbon steel in 1 wt.% sodium chloride (NaCl) solution

    Science.gov (United States)

    Razak, Khalil Abdul; Fuad, Mohd Fazril Irfan Ahmad; Alias, Nur Hashimah; Othman, Nur Hidayati; Zahari, Muhammad Imran

    2017-12-01

    Special attention has been paid in the past decade on the use of metal corrosion protection to conserve natural resources and to improve the performance of engine, build structures and other equipment. Coating is considered as one of the promising methods that can be used to protect the metal against corrosion. However, not many attentions have been given on the evaluation of coating mechanism towards corrosion protection. In this work, the performance of zinc-rich paint (ZRP) was investigated under saltwater environment as to simulate the nature of corrosion in seawater. The adhesion of the coated steel was also studied to determine the adherence of the coatings to the metal substrate. Results obtained from the immersion test was then used to determine the corrosion rate of the coatings. The mechanisms and the function of ZRP as a protection layer were also investigated. By using 3 coated system of ZRP, the corrosion rate of the steel was observed to decrease thus provide better protection in seawater environment.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-02-01

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

  10. Development of low-temperature galvanizing and its application for corrosion protection of high-strength steels; Entwicklung einer niedrigschmelzenden Legierung und deren Applikation zum Korrosionsschutz hochfester Staehle

    Energy Technology Data Exchange (ETDEWEB)

    Wielage, B.; Lampke, T.; Steinhaeuser, S. [Technische Universitaet Chemnitz (Germany). Institut fuer Werkstoffwissenschaft und Werkstofftechnik; Strobel, C. [Fachhochschule Ingolstadt (Germany); Merklinger, V.

    2008-12-15

    Apart from reliability and quality, vehicle safety and cost efficiency are the decisive criteria for automobile manufacturers. Corrosion protection plays a decisive role because it increases the service life. The ultra-high-strength steels are materials which exhibit high lightweight potential as well as a very good energy absorption capacity because of their mechanical properties. In connection with the possibility of hot forming, they are predestined for the fabrication of complicated, load-compatible shapes in the crash-relevant frame and body construction. The application of these steel qualities has been carried out in structural parts which are protected from corrosion by a hot-dip coat of FeAl7 - the so-called Usibor. However, at the moment there is no ready-for-production solution for later corrosion protection of already hot-formed parts. Therefore, a corrosion protection system on the basis of conventional low-temperature galvanizing processes has been developed and utilized. First, the softening behavior of the highly-resistant 22MnB5 substrate was analyzed. Afterwards, a galvanizing system was developed and applied. The corrosion protection coatings were characterized with regard to their structure and corrosion protection potential. As a result, a significant improvement of the corrosion behaviour has occurred. (Abstract Copyright [2008], Wiley Periodicals, Inc.) [German] Neben Zuverlaessigkeit und Qualitaet sind vor allem Fahrzeugsicherheit und Wirtschaftlichkeit entscheidende Kriterien fuer den Automobilhersteller. Der Korrosionsschutz spielt dabei eine herausragende Rolle, da hierdurch die Lebens- und Gebrauchsdauer erhoeht wird. Mit der Bereitstellung hoechstfester Stahlqualitaeten stehen Werkstoffe zur Verfuegung, die auf Grund ihrer mechanischen Eigenschaften ein hohes Leichtbaupotenzial sowie ein sehr gutes Energieabsorptionsvermoegen aufweisen. In Verbindung mit der Moeglichkeit der Warmformgebung sind sie damit praedestiniert fuer die

  11. Corrosion Fatigue Crack Propagation Rate Characteristics for Weldable Ship and Offshore Steels with Regard to the Influence of Loading Frequency and Saltwater Temperature

    Directory of Open Access Journals (Sweden)

    Jakubowski Marek

    2017-03-01

    Full Text Available After Vosikovsky (1975, the corrosion fatigue crack growth rate (CFCGR characteristics have been divided into three regions. The region-III rates are very close to mechanical fatigue crack growth rates. CFCGR formulae, including the long-crack length effect (in region I only, the loading frequency effect (in region II only, and the saltwater temperature effect, have been proposed. It has been assumed that CFCGR is proportional to f-k, where f is the loading frequency and k is a constant. The averaged k-value for all steels of yield stress (YS below 500 MPa, usually with ferrite-pearlite microstructures, is higher than that for YS > 500 MPa, usually with quenched and tempered microstructures. The temperature effect does not appear in region I below room temperature. In the remaining cases, that is, in region I for elevated temperatures and in region II for both low and elevated temperatures, the CFCGR increases with increasing temperature. Under a potential of -0.8 V, a long-crack-length effect, qualitatively similar to analogous effect for free corrosion conditions, appears.

  12. Combining hygrothermal and corrosion models to predict corrosion of metal fasteners embedded in wood

    Science.gov (United States)

    Samuel L. Zelinka; Dominique Derome; Samuel V. Glass

    2011-01-01

    A combined heat, moisture, and corrosion model is presented and used to simulate the corrosion of metal fasteners embedded in solid wood exposed to the exterior environment. First, the moisture content and temperature at the wood/fastener interface is determined at each time step. Then, the amount of corrosion is determined spatially using an empirical corrosion rate...

  13. Effects of lead on oxidation behavior of Alloy 690TT within a high temperature aqueous environment

    Science.gov (United States)

    Hou, Qiang; Liu, Zhiyong; Li, Chengtao; Li, Xiaogang

    2017-12-01

    The chemical compositions, phases and structures of two oxide films on Alloy 690TT following exposure for 4400 h in pure water with and without lead at 320 °C were studied by surface analysis techniques. The analysis of a lead-doped oxide film prepared by a focused ion beam (FIB) demonstrated that both Cr-rich and Ni-rich oxides were alternatively distributed within the outer layer, whereas the inner layer was porous and poorly protected, causing severe corrosion of the alloy and a thicker film was formed. A duplex film model was proposed for the effects discussion of lead on the oxidation mechanism.

  14. Aqueous solutions of proline and NaCl studied by differential scanning calorimetry at subzero temperatures

    DEFF Research Database (Denmark)

    Rasmussen, Peter Have; Jørgensen, Bo; Nielsen, Jette

    1997-01-01

    The hydration properties of proline are studied by differential scanning calorimetry (DSC) in aqueous solutions during freezing to -60 degrees C and subsequent heating to +20 degrees C. The concentration of proline in the freeze concentrated solution was estimated to approximately 50 wt% (w...

  15. Model for the Surface Tension of Dilute and Concentrated Binary Aqueous Mixtures as a Function of Composition and Temperature.

    Science.gov (United States)

    Shardt, Nadia; Elliott, Janet A W

    2017-10-17

    Surface tension dictates fluid behavior, and predicting its magnitude is vital in many applications. Equations have previously been derived to describe how the surface tension of pure liquids changes with temperature, and other models have been derived to describe how the surface tension of mixtures changes with liquid-phase composition. However, the simultaneous dependence of surface tension on temperature and composition for liquid mixtures has been less studied. Past approaches have required extensive experimental data to which models have been fit, yielding a distinct set of fitting parameters at each temperature or composition. Herein, we propose a model that requires only three fitting procedures to predict surface tension as a function of temperature and composition. We achieve this by analyzing and extending the Shereshefsky (J. Colloid Interface Sci. 1967, 24 (3), 317-322), Li et al. (Fluid Phase Equilib. 2000, 175, 185-196), and Connors-Wright (Anal. Chem. 1989, 61 (3), 194-198) models to high temperatures for 15 aqueous systems. The best extensions of the Shereshefsky, Li et al., and Connors-Wright models achieve average relative deviations of 2.11%, 1.20%, and 0.62%, respectively, over all systems. We thus recommend the extended Connors-Wright model for predicting the surface tension of aqueous mixtures at different temperatures with the tabulated coefficients herein. An additional outcome of this study is the previously unreported equivalence of the Li et al. and Connors-Wright models in describing experimental data of surface tension as a function of composition at a single temperature.

  16. Development of advanced metallic coatings resistant to corrosion in high temperature industrial atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Weber, T.; Bender, R.; Rosado, C.; Schuetze, M. [DECHEMA e.V., Frankfurt am Main (Germany)

    2004-07-01

    Following the experimental results that {gamma}-TiAl is highly resistant in reducing sulfidizing atmospheres the development of Ti-Al-co-diffusion coatings produced in a single step pack cementation process was started. The appropriate diffusion powder compositions were selected using thermodynamical calculations. Different Al-Ti-, Al-Si- and Al-Ti-Si-diffusion coatings were successfully applied on austenitic steels as well as Ni-base materials and showed excellent behaviour in reducing sulfidizing atmospheres with high carbon contents (CH{sub 4} - 1% CO - 1% CO{sub 2} - 10% H{sub 2} - 7% H{sub 2}S) up to 700 deg. C, under metal dusting conditions (H{sub 2} - 25 CO - 2% H{sub 2}O and CO - 2.4% CO{sub 2} - 1% CH{sub 4} - 9.4% N{sub 2} - 23.4% H{sub 2} - 0.2% H{sub 2}O - 1 ppm H{sub 2}S-0.3 ppm HCl) at temperatures of 620 deg. C and 700 deg. C. The application of diffusion coatings on ferritic materials has to be modified due to the specific requirements on the mechanical properties which are affected by the heat treatment during the diffusion process. TiAl was also applied by the HVOF thermal spray method on ferritic steels. Due to similarity of the thermal expansion coefficients this substrate-coating system proved to be mechanically very stable also under thermal cycling conditions. (authors)

  17. The influence of deposition temperature on microstructure and corrosion resistance of ZrOxNy/ZrO₂ coatings deposited using RF sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Cubillos, G.I., E-mail: gcubillos@unal.edu.co [Department of Chemistry, Faculty of Science, National University of Colombia, Av. Cra. 30 No 45-03, Bogotá (Colombia); Bethencourt, M., E-mail: manuel.bethencourt@uca.es [Department of Materials Science, Metallurgy Engineering and Inorganic Chemistry, International Campus of Excellence of the Sea (CEI-MAR), University of Cadiz, Avda. República Saharaui s/n, 11510 Puerto Real, Cádiz (Spain); Olaya, J.J., E-mail: jjolayaf@unal.edu.co [Department of Mechanical Engineering, Faculty of Engineering, National University of Colombia, Bogotá (Colombia); Alfonso, J.E., E-mail: jealfonsoo@unal.edu.co [Department of Physic, Faculty of Science, National University of Colombia, Av. Cra. 30 No 45-03, Bogotá (Colombia); Marco, J.F., E-mail: jfmarco@iqfr.csic.es [Instituto de Química Física “Rocasolano”, CSIC, C/Serrano 119, 28006 Madrid (Spain)

    2014-08-01

    This paper reports the influence of substrate temperature on the structure, morphology and corrosion resistance of ZrOxNy/ZrO₂ thin films deposited on 304 stainless steel using radio frequency sputtering (RF sputtering). Structural analysis was carried out by X-ray diffraction (XRD); morphological analysis was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and surface chemical analysis was determined using X-ray photoelectron spectroscopy (XPS). XRD data showed that the films deposited at 300 °C (573 K) and 350 °C (623 K) result in the growth of a monoclinic zirconium oxynitride phase with preferential orientation along the (-1 1 1) plane, while at 14 °C (287 K) the predominant phase is of polycrystalline ZrO₂. The corrosion results indicate that the coatings provide good resistance to corrosion in chloride-containing media, being better in the film deposited at 350 °C (623 K). SEM analysis demonstrated the homogeneity of the films deposited at the three temperatures; AFM studies established the average roughness of the films to be 4.25 nm. The binding energies of the Zr 3d, N 1s, and O 1s core levels determined by XPS were all compatible with the formation of a zirconium oxynitride and zirconium oxide in the surface of the film. ZrOxNy/ZrO₂ thin films are promising candidates for increasing the corrosion resistance of the steels in chloride-rich environments.

  18. Influence of pyrolysis temperature on lead immobilization by chemically modified coconut fiber-derived biochars in aqueous environments.

    Science.gov (United States)

    Wu, Weidong; Li, Jianhong; Niazi, Nabeel Khan; Müller, Karin; Chu, Yingchao; Zhang, Lingling; Yuan, Guodong; Lu, Kouping; Song, Zhaoliang; Wang, Hailong

    2016-11-01

    Biochar has received widespread attention as an eco-friendly and efficient material for immobilization of toxic heavy metals in aqueous environments. In the present study, three types of coconut fiber-derived biochars were obtained by pyrolyzing at three temperatures, i.e., 300, 500, and 700 °C. In addition, nine types of biochars were prepared by chemical modification with ammonia, hydrogen peroxide, and nitric acid, respectively, which were used to investigate changes in physico-chemical properties by inter alia, Fourier transformation infrared spectrophotometry (FTIR), scanning electron microscope (SEM), and BET specific surface area analysis. Batch sorption experiments were carried out to determine the sorption capacity of the biochars for lead (Pb) in aqueous solutions. Results showed that the cation exchange capacity of biochar pyrolyzed at 300 °C and modified with nitric acid increased threefold compared to the control. Loosely corrugated carbon surface and uneven carbon surface of the biochar pyrolyzed at 300 °C were produced during ammonia and nitric acid modifications. Removal rate of Pb by the coconut biochar pyrolyzed at 300 °C and modified with ammonia was increased from 71.8 to 99.6 % compared to the untreated biochar in aqueous solutions containing 100 mg L(-1) Pb. However, chemical modification did not enhance adsorption of Pb of the biochars pyrolyzed at higher temperatures (e.g., 500 or 700 °C), indicating that resistance of biochars to chemical treatment increased with pyrolysis temperature.

  19. Study of alloy 600`S stress corrosion cracking mechanisms in high temperature water; Etude des mecanismes de corrosion sous contrainte de l`alliage 600 dans l`eau a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Rios, R.

    1994-06-01

    In order to better understand the mechanisms involved in Alloy 600`s stress corrosion cracking in PWR environment, laboratory tests were performed. The influence of parameters pertinent to the mechanisms was studies : hydrogen and oxygen overpressures, local chemical composition, microstructure. The results show that neither hydrogen nor dissolution/oxidation, despite their respective roles in the process, are sufficient to account for experimental facts. SEM observation of micro-cleavage facets on specimens` fracture surfaces leads to pay attention to a new mechanism of corrosion/plasticity interactions. (author). 113 refs., 73 figs., 15 tabs., 4 annexes.

  20. Aqueous singlet oxygen reaction kinetics of furfuryl alcohol: effect of temperature, pH, and salt content.

    Science.gov (United States)

    Appiani, Elena; Ossola, Rachele; Latch, Douglas E; Erickson, Paul R; McNeill, Kristopher

    2017-04-19

    The rate constant for the reaction between furfuryl alcohol (FFA) and singlet oxygen ( 1 O 2 ) in aqueous solution was measured as a function of temperature, pH and salt content employing both steady-state photolysis (β value determination) and time-resolved singlet oxygen phosphorescence methods. The latter provided more precise and reproducible data. The reaction rate constant, k rxn,FFA , had a relatively small temperature dependence, no pH dependence and showed a small increase in the presence of high salt concentrations (+19% with 1 M NaCl). A critical review of the available literature suggested that the widely used value of 1.2 × 10 8 M -1 s -1 is likely overestimated. Therefore, we recommend the use of 1.00 × 10 8 M -1 s -1 for reactions performed in low ionic strength aqueous solutions (freshwater) at 22 °C. Furthermore, corrections are provided that should be applied when working at higher or lower temperatures, and/or at high salt concentrations (seawater).

  1. Corrosion Protection of Aluminum

    Science.gov (United States)

    Dalrymple, R. S.; Nelson, W. B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred.

  2. A Fiber-Optic Sensor Using an Aqueous Solution of Sodium Chloride to Measure Temperature and Water Level Simultaneously

    Science.gov (United States)

    Yoo, Wook Jae; Sim, Hyeok In; Shin, Sang Hun; Jang, Kyoung Won; Cho, Seunghyun; Moon, Joo Hyun; Lee, Bongsoo

    2014-01-01

    A fiber-optic sensor system using a multiplexed array of sensing probes based on an aqueous solution of sodium chloride (NaCl solution) and an optical time-domain reflectometer (OTDR) for simultaneous measurement of temperature and water level is proposed. By changing the temperature, the refractive index of the NaCl solution is varied and Fresnel reflection arising at the interface between the distal end of optical fiber and the NaCl solution is then also changed. We measured the modified optical power of the light reflected from the sensing probe using a portable OTDR device and also obtained the relationship between the temperature of water and the optical power. In this study, the water level was simply determined by measuring the signal difference of the optical power due to the temperature difference of individual sensing probes placed inside and outside of the water. In conclusion, we demonstrate that the temperature and water level can be obtained simultaneously by measuring optical powers of light reflected from sensing probes based on the NaCl solution. It is anticipated that the proposed fiber-optic sensor system makes it possible to remotely monitor the real-time change of temperature and water level of the spent fuel pool during a loss of power accident. PMID:25310471

  3. A Fiber-Optic Sensor Using an Aqueous Solution of Sodium Chloride to Measure Temperature and Water Level Simultaneously

    Directory of Open Access Journals (Sweden)

    Wook Jae Yoo

    2014-10-01

    Full Text Available A fiber-optic sensor system using a multiplexed array of sensing probes based on an aqueous solution of sodium chloride (NaCl solution and an optical time-domain reflectometer (OTDR for simultaneous measurement of temperature and water level is proposed. By changing the temperature, the refractive index of the NaCl solution is varied and Fresnel reflection arising at the interface between the distal end of optical fiber and the NaCl solution is then also changed. We measured the modified optical power of the light reflected from the sensing probe using a portable OTDR device and also obtained the relationship between the temperature of water and the optical power. In this study, the water level was simply determined by measuring the signal difference of the optical power due to the temperature difference of individual sensing probes placed inside and outside of the water. In conclusion, we demonstrate that the temperature and water level can be obtained simultaneously by measuring optical powers of light reflected from sensing probes based on the NaCl solution. It is anticipated that the proposed fiber-optic sensor system makes it possible to remotely monitor the real-time change of temperature and water level of the spent fuel pool during a loss of power accident.

  4. An integrated model of tritium transport and corrosion in Fluoride Salt-Cooled High-Temperature Reactors (FHRs) – Part I: Theory and benchmarking

    Energy Technology Data Exchange (ETDEWEB)

    Stempien, John D., E-mail: john.stempien@inl.gov; Ballinger, Ronald G., E-mail: hvymet@mit.edu; Forsberg, Charles W., E-mail: cforsber@mit.edu

    2016-12-15

    Highlights: • A model was developed for use with FHRs and benchmarked with experimental data. • Model results match results of tritium diffusion experiments. • Corrosion simulations show reasonable agreement with molten salt loop experiments. • This is the only existing model of tritium transport and corrosion in FHRs. • Model enables proposing and evaluating tritium control options in FHRs. - Abstract: The Fluoride Salt-Cooled High-Temperature Reactor (FHR) is a pebble bed nuclear reactor concept cooled by a liquid fluoride salt known as “flibe” ({sup 7}LiF-BeF{sub 2}). A model of TRITium Diffusion EvolutioN and Transport (TRIDENT) was developed for use with FHRs and benchmarked with experimental data. TRIDENT is the first model to integrate the effects of tritium production in the salt via neutron transmutation, with the effects of the chemical redox potential, tritium mass transfer, tritium diffusion through pipe walls, tritium uptake by graphite, selective chromium attack by tritium fluoride, and corrosion product mass transfer. While data from a forced-convection polythermal loop of molten salt containing tritium did not exist for comparison, TRIDENT calculations were compared to data from static salt diffusion tests in flibe and flinak (0.465LiF-0.115NaF-0.42KF) salts. In each case, TRIDENT matched the transient and steady-state behavior of these tritium diffusion experiments. The corrosion model in TRIDENT was compared against the natural convection flow-loop experiments at the Oak Ridge National Laboratory (ORNL) from the 1960s and early 1970s which used Molten Salt Reactor Experiment (MSRE) fuel-salt containing UF{sub 4}. Despite the lack of data required by TRIDENT for modeling the loops, some reasonable results were obtained. The TRIDENT corrosion rates follow the experimentally observed dependence on the square root of the product of the chromium solid-state diffusion coefficient with time. Additionally the TRIDENT model predicts mass

  5. Diversity and Composition of Sulfate-Reducing Microbial Communities Based on Genomic DNA and RNA Transcription in Production Water of High Temperature and Corrosive Oil Reservoir

    Science.gov (United States)

    Li, Xiao-Xiao; Liu, Jin-Feng; Zhou, Lei; Mbadinga, Serge M.; Yang, Shi-Zhong; Gu, Ji-Dong; Mu, Bo-Zhong

    2017-01-01

    Deep subsurface petroleum reservoir ecosystems harbor a high diversity of microorganisms, and microbial influenced corrosion is a major problem for the petroleum industry. Here, we used high-throughput sequencing to explore the microbial communities based on genomic 16S rDNA and metabolically active 16S rRNA analyses of production water samples with different extents of corrosion from a high-temperature oil reservoir. Results showed that Desulfotignum and Roseovarius were the most abundant genera in both genomic and active bacterial communities of all the samples. Both genomic and active archaeal communities were mainly composed of Archaeoglobus and Methanolobus. Within both bacteria and archaea, the active and genomic communities were compositionally distinct from one another across the different oil wells (bacteria p = 0.002; archaea p = 0.01). In addition, the sulfate-reducing microorganisms (SRMs) were specifically assessed by Sanger sequencing of functional genes aprA and dsrA encoding the enzymes adenosine-5′-phosphosulfate reductase and dissimilatory sulfite reductase, respectively. Functional gene analysis indicated that potentially active Archaeoglobus, Desulfotignum, Desulfovibrio, and Thermodesulforhabdus were frequently detected, with Archaeoglobus as the most abundant and active sulfate-reducing group. Canonical correspondence analysis revealed that the SRM communities in petroleum reservoir system were closely related to pH of the production water and sulfate concentration. This study highlights the importance of distinguishing the metabolically active microorganisms from the genomic community and extends our knowledge on the active SRM communities in corrosive petroleum reservoirs. PMID:28638372

  6. Diversity and Composition of Sulfate-Reducing Microbial Communities Based on Genomic DNA and RNA Transcription in Production Water of High Temperature and Corrosive Oil Reservoir

    Directory of Open Access Journals (Sweden)

    Xiao-Xiao Li

    2017-06-01

    Full Text Available Deep subsurface petroleum reservoir ecosystems harbor a high diversity of microorganisms, and microbial influenced corrosion is a major problem for the petroleum industry. Here, we used high-throughput sequencing to explore the microbial communities based on genomic 16S rDNA and metabolically active 16S rRNA analyses of production water samples with different extents of corrosion from a high-temperature oil reservoir. Results showed that Desulfotignum and Roseovarius were the most abundant genera in both genomic and active bacterial communities of all the samples. Both genomic and active archaeal communities were mainly composed of Archaeoglobus and Methanolobus. Within both bacteria and archaea, the active and genomic communities were compositionally distinct from one another across the different oil wells (bacteria p = 0.002; archaea p = 0.01. In addition, the sulfate-reducing microorganisms (SRMs were specifically assessed by Sanger sequencing of functional genes aprA and dsrA encoding the enzymes adenosine-5′-phosphosulfate reductase and dissimilatory sulfite reductase, respectively. Functional gene analysis indicated that potentially active Archaeoglobus, Desulfotignum, Desulfovibrio, and Thermodesulforhabdus were frequently detected, with Archaeoglobus as the most abundant and active sulfate-reducing group. Canonical correspondence analysis revealed that the SRM communities in petroleum reservoir system were closely related to pH of the production water and sulfate concentration. This study highlights the importance of distinguishing the metabolically active microorganisms from the genomic community and extends our knowledge on the active SRM communities in corrosive petroleum reservoirs.

  7. Corrosion Monitors for Embedded Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Alex L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pfeifer, Kent B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Casias, Adrian L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sorensen, Neil R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    We have developed and characterized novel in-situ corrosion sensors to monitor and quantify the corrosive potential and history of localized environments. Embedded corrosion sensors can provide information to aid health assessments of internal electrical components including connectors, microelectronics, wires, and other susceptible parts. When combined with other data (e.g. temperature and humidity), theory, and computational simulation, the reliability of monitored systems can be predicted with higher fidelity.

  8. Producing Zirconium Diboride Components with Complex, Near-Net Shape Geometries by Aqueous Room-Temperature Injection Molding

    Science.gov (United States)

    Wiesner, Valerie L.; Youngblood, Jeffrey; Trice, Rodney

    2014-01-01

    Room-temperature injection molding is proposed as a novel, low-cost and more energy efficient manufacturing process capable of forming complex-shaped zirconium diboride (ZrB2) parts. This innovative processing method utilized aqueous suspensions with high powder loading and a minimal amount (5 vol.) of water-soluble polyvinylpyrrolidone (PVP), which was used as a viscosity modifier. Rheological characterization was performed to evaluate the room-temperature flow properties of ZrB2-PVP suspensions. ZrB2 specimens were fabricated with high green body strength and were machinable prior to binder removal despite their low polymer content. After binder burnout and pressureless sintering, the bulk density and microstructure of specimens were characterized using Archimedes technique and scanning electron microscopy. X-Ray Diffraction was used to determine the phase compositions present in sintered specimens. Ultimate strength of sintered specimens will be determined using ASTM C1323-10 compressive C-ring test.

  9. Studies on the Solute Solvent Interaction of Nimesulide in Aqueous Solutions of Hydrotropic Agents at Different Temperatures

    Directory of Open Access Journals (Sweden)

    Chandravir S. Solanki

    2010-01-01

    Full Text Available The present study deals with experiments so as to highlight the solute (drug nimesulide - solvent(water interactions and related modifications in case of the presence of hydrotropic agents at different temperatures T(=298.15 to 313.15K. Density and viscosity values of nimesulide have been determined in water in (0.1, 0.2, 0.4, 0.6, 0.8, 1 and 2 mol dm-3 aqueous solutions of hydrotropic agents (sodium benzoate, sodium salicylate, sodium bromide and nicotinamide at temperatures 298.15, 303.15, 308.15 and 313.15 K where as the solubility was studied at 308.15 K. From the density values, the limiting partial molar volumes and expansibilities have been calculated. The experimental viscosity values have been analyzed in terms of jones-dole equation and on the basis of transition theory for relative viscosity.

  10. Conductometric and volumetric study of copper sulphate in aqueous ethanol solutions at different temperatures

    OpenAIRE

    Esam A Gomaa; Negm, Amr; Tahoon, Mohamed A.

    2016-01-01

    An Anton Par Model 55 densimeter was used to measure the densities of copper sulphate solutions in H2O and EtOH–H2O at 298.15 K, 303.15 K, 308.15 K, and 313.15 K. The acquired information was used to ascertain the apparent molar volumes, limiting partial molar volumes, and transfer partial molar volumes of copper sulphate. These computed parameters were utilized to decipher the solute–solute and solute–solvent interactions of copper sulphate in an aqueous ethanol solution. The ion solvation b...

  11. High-Temperature Corrosion of AlCrSiN Film in Ar-1%SO2 Gas

    Directory of Open Access Journals (Sweden)

    Poonam Yadav

    2017-03-01

    Full Text Available AlCrSiN film with a composition of 29.1Al-17.1Cr-2.1Si-51.7N in at. % was deposited on a steel substrate by cathodic arc ion plating at a thickness of 1.8 μm. It consisted of nanocrystalline hcp-AlN and fcc-CrN, where a small amount of Si was dissolved. Corrosion tests were carried out at 800 °C for 5–200 h in Ar-1%SO2 gas. The major corrosion reaction was oxidation owing to the high oxygen affinity of Al and Cr in the film. The formed oxide scale consisted primarily of (Al,Cr2O3, within which Fe, Si, and S were dissolved. Even after corrosion for 200 h, the thickness of the scale was about 0.7–1.2 μm, indicating that the film had good corrosion resistance in the SO2-containing atmosphere.

  12. High temperature corrosion of cold worked YUS409D bellows of bellow-sealed valve in LBE

    Science.gov (United States)

    Mustari1, A. P. A.; Irwanto1, D.; Takahashi, M.

    2017-01-01

    Lead-bismuth eutectic (LBE) loop test is highly contributes to the lead-alloy-cooled fast breeder reactor (LFR) and accelerator driven system (ADS) research and development by providing comprehensive results of both corrosion and erosion phenomenon. Bellows-sealed valve is a crucial part in the LBE loop test apparatus, due to its capability of preventing corrosion on valve spring, thus improves the operation time of the system. LBE is very corrosive to stainless steel by formation of oxide layer or elemental dissolution, e.g. Ni. Thus, new type of bellows for bellows-sealed valve made of nickel free material, i.e. YUS409D, is proposed to be used in the LBE. Bellows material undergo heat treatments for mechanical improvement including cold working and annealing. The thickness reduction by the heat treatments is about 90% of initial condition. Corrosion behavior of the bellows has been studied in stagnant LBE at 500 and 600 °C for 500 hours. The oxygen concentration was controlled at about 10-7 wt%. Typical oxide layers were developed on the surface. Oxidation rate was sharply increased at 600°C.

  13. Volumetric behaviour of amino acids and their group contributions in aqueous lactose solutions at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Amalendu, E-mail: palchem@sify.co [Department of Chemistry, Kurukshetra University, Kurukshetra 136 119 (India); Chauhan, Nalin [Department of Chemistry, Kurukshetra University, Kurukshetra 136 119 (India)

    2011-02-15

    Densities, {rho}, for glycine, L-alanine, L-valine, and L-leucine [(0.05 to 0.30) m] in aqueous lactose solutions ranging from pure water to 6 mass% lactose were determined at T = (293.15, 298.15, 303.15, and 308.15) K. The density was used to compute apparent molar volume, V{sub {phi}}, partial molar volume at infinite dilution, V{sub {phi}}{sup o}, and experimental slope, S{sub V} were obtained and interpreted in terms of solute-solvent and solute-solute interactions. These data were used to calculate the ({partial_derivative}V{sub {phi}}{sup 0}/{partial_derivative}T){sub P} values. The partial molar volume of transfer, {Delta}V{sub {phi}}{sup 0} from water to aqueous lactose solutions at infinite dilution has also been calculated. In addition to this, the linear correlation of V{sub {phi}}{sup 0} with number of carbon atoms in the alkyl chain of amino acids was utilized to determine the respective contributions of NH{sub 3}{sup +}COO{sup -}, and CH{sub 2} groups to V{sub {phi}}{sup 0}.

  14. Low-temperature aqueous alteration on the CR chondrite parent body: Implications from in situ oxygen-isotope analyses

    Science.gov (United States)

    Jilly-Rehak, Christine E.; Huss, Gary R.; Nagashima, Kazu; Schrader, Devin L.

    2018-02-01

    The presence of hydrated minerals in chondrites indicates that water played an important role in the geologic evolution of the early Solar System; however, the process of aqueous alteration is still poorly understood. Renazzo-like carbonaceous (CR) chondrites are particularly well-suited for the study of aqueous alteration. Samples range from being nearly anhydrous to fully altered, essentially representing snapshots of the alteration process through time. We studied oxygen isotopes in secondary-minerals from six CR chondrites of varying hydration states to determine how aqueous fluid conditions (including composition and temperature) evolved on the parent body. Secondary minerals analyzed included calcite, dolomite, and magnetite. The O-isotope composition of calcites ranged from δ18O ≈ 9 to 35‰, dolomites from δ18O ≈ 23 to 27‰, and magnetites from δ18O ≈ -18 to 5‰. Calcite in less-altered samples showed more evidence of fluid evolution compared to heavily altered samples, likely reflecting lower water/rock ratios. Most magnetite plotted on a single trend, with the exception of grains from the extensively hydrated chondrite MIL 090292. The MIL 090292 magnetite diverges from this trend, possibly indicating an anomalous origin for the meteorite. If magnetite and calcite formed in equilibrium, then the relative 18O fractionation between them can be used to extract the temperature of co-precipitation. Isotopic fractionation in Al Rais carbonate-magnetite assemblages revealed low precipitation temperatures (∼60 °C). Assuming that the CR parent body experienced closed-system alteration, a similar exercise for parallel calcite and magnetite O-isotope arrays yields "global" alteration temperatures of ∼55 to 88 °C. These secondary mineral arrays indicate that the O-isotopic composition of the altering fluid evolved upon progressive alteration, beginning near the Al Rais water composition of Δ17O ∼ 1‰ and δ18O ∼ 10‰, and becoming increasingly

  15. High temperature corrosion studies. A. Iron: based superalloy in SO/sub 2//O/sub 2/ atmospheres. B. Gas: solid reaction with formation of volatile species

    Energy Technology Data Exchange (ETDEWEB)

    Liu, T.K.

    1980-03-01

    The thermogravimetric method was used to study high temperature corrosion under SO/sub 2//O/sub 2/ atmosphere applied to Armco 18SR alloys with different heat treatment histories, Armco T310 and pure chromium between 750 and 1100/sup 0/C. The weight gain follows the parabolic rate law. The volatilization of the protective Cr/sub 2/O/sub 3/ layer via formation of CrO/sub 3/ was taken into account above 900/sup 0/C for long time runs. The parabolic rate and the volatilization rate, derived from fitting the experimental data to the modified Tedmon's non-linear model, were correlated using the Arrhenius equation. Armco 18SR-C has the best corrosion resistance of the Armco 18SR alloys. Armco T310 is not protective at high temperatures. The available rate data on the oxidation of chromium oxide, chlorination of chromium, oxidation-chlorination of chromium oxide, chlorination of nickel and chlorination of iron were found to be predictable. The calculation of high temperature volatilization rate was performed using the available fluid correlation equations and the Lennard-Jones parameters derived from the molecule with similar structure and from the low temperature viscosity measurement. The lower predicted volatilization rate is due to the use of the Chapman-Enskog equation with the Lennard-Jones parameters mostly derived from the low temperature viscosity measurement. This was substantiated by comparing the reliable high temperature diffusion rate in the literature with the above mentioned calculational method. The experimental volatilization rates of this study are compared with the other related studies and the mass transfer predictions.

  16. Room temperature phosphorescence lifetime and quantum yield of erythrosine B and rose bengal in aerobic alkaline aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Penzkofer, A., E-mail: alfons.penzkofer@physik.uni-regensburg.de [Fakultaet fuer Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany); Simmel, M.; Riedl, D. [Fakultaet fuer Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany)

    2012-04-15

    The room-temperature phosphorescence behavior of erythrosine B (ER) and rose bengal (RB) in aerobic aqueous solution at pH 10 (10{sup -4} M NaOH) is investigated. The samples were excited with sliced second harmonic pulses of a Q-switched Nd:glass laser. A gated photomultiplier tube was used for instantaneous fluorescence signal discrimination and a digital oscilloscope was used for signal recording. For phosphorescence lifetime measurement the oscilloscope response time was adjusted to appropriate time resolution and sensitivity by the ohmic input resistance. In the case of phosphorescence quantum yield determination the gated photomultiplier - oscilloscope arrangement was operated in integration mode using 10 M{Omega} input resistance. Phosphorescence quantum yield calibration was achieved with erythrosine B and rose bengal doped starch films of known quantum yields. The determined phosphorescence lifetimes (quantum yields) of ER and RB in 0.1 mM NaOH are {tau}{sub P}=1.92{+-}0.1 {mu}s ({phi}{sub P}=(1.5{+-}0.3) Multiplication-Sign 10{sup -5}) and 2.40{+-}0.1 {mu}s ((5.7{+-}0.9) Multiplication-Sign 10{sup -5}), respectively. The results are discussed in terms of triplet state deactivation by dissolved molecular oxygen. - Highlights: Black-Right-Pointing-Pointer Phosphorescence lifetime of fluorone dyes in aerobe aqueous solution is measured. Black-Right-Pointing-Pointer Phosphorescence quantum yield of fluorone dyes in aerobe solution is determined. Black-Right-Pointing-Pointer Experimental setup with Q-switched laser and gated PMT detection is described. Black-Right-Pointing-Pointer Phosphorescence quenching by dissolved molecular oxygen is analyzed. Black-Right-Pointing-Pointer Absorption and fluorescence behavior of fluorones in aqueous solution is studied.

  17. The Stress Corrosion Resistance and the Cryogenic Temperature Mechanical Behavior of 18-3 Mn (Nitronic 33) Stainless Steel Parent and Welded Material

    Science.gov (United States)

    Montano, J. W.

    1976-01-01

    The ambient and cryogenic temperature mechanical properties and the ambient temperature stress corrosion results of 18-3 Mn (Nitronic 33)stainless steel, longitudinal and transverse, as received and as welded (TIG) material specimens manufactured from 0.063 inch thick sheet material, were described. The tensile test results indicate an increase in ultimate tensile and yield strengths with decreasing temperature. The elongation remained fairly constant to -200 F, but below that temperature the elongation decreased to less than 6.0% at liquid hydrogen temperature. The notched tensile strength (NTS) for the parent metal increased with decreasing temperature to liquid nitrogen temperature. Below -320 F the NTS decreased rapidly. The notched/unnotched (N/U) tensile ratio of the parent material specimens remained above 0.9 from ambient to -200 F, and decreased to approximately 0.65 and 0.62, respectively, for the longitudinal and transverse directions at liquid hydrogen temperature. After 180 days of testing, only those specimens exposed to the salt spray indicated pitting and some degradation of mechanical properties.

  18. Electrolytic conductivity and molar heat capacity of two aqueous solutions of ionic liquids at room-temperature: Measurements and correlations

    Energy Technology Data Exchange (ETDEWEB)

    Lin Peiyin [R and D Center for Membrane Technology and Department of Chemical Engineering, Chung Yuan Christian University, Chung Li 32023, Taiwan (China); Soriano, Allan N. [R and D Center for Membrane Technology and Department of Chemical Engineering, Chung Yuan Christian University, Chung Li 32023, Taiwan (China); School of Chemical Engineering and Chemistry, Mapua Institute of Technology, Manila 1002 (Philippines); Leron, Rhoda B. [R and D Center for Membrane Technology and Department of Chemical Engineering, Chung Yuan Christian University, Chung Li 32023, Taiwan (China); Li Menghui, E-mail: mhli@cycu.edu.t [R and D Center for Membrane Technology and Department of Chemical Engineering, Chung Yuan Christian University, Chung Li 32023, Taiwan (China)

    2010-08-15

    As part of our systematic study on physicochemical characterization of ionic liquids, in this work, we report new measurements of electrolytic conductivity and molar heat capacity for aqueous solutions of two 1-ethyl-3-methylimidazolium-based ionic liquids, namely: 1-ethyl-3-methylimidazolium dicyanamide and 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate, at normal atmospheric condition and for temperatures up to 353.2 K. The electrolytic conductivity and molar heat capacity were measured by a commercial conductivity meter and a differential scanning calorimeter (DSC), respectively. The estimated experimental uncertainties for the electrolytic conductivity and molar heat capacity measurements were {+-}1% and {+-}2%, respectively. The property data are reported as functions of temperature and composition. A modified empirical equation from another researcher was used to correlate the temperature and composition dependence of the our electrolytic conductivity results. An excess molar heat capacity expression derived using a Redlich-Kister type equation was used to represent the temperature and composition dependence of the measured molar heat capacity and calculated excess molar heat capacity of the solvent systems considered. The correlations applied represent the our measurements satisfactorily as shown by an acceptable overall average deviation of 6.4% and 0.1%, respectively, for electrolytic conductivity and molar heat capacity.

  19. Corrosion protection

    Science.gov (United States)

    Brown, Donald W.; Wagh, Arun S.

    2003-05-27

    There has been invented a chemically bonded phosphate corrosion protection material and process for application of the corrosion protection material for corrosion prevention. A slurry of iron oxide and phosphoric acid is used to contact a warm surface of iron, steel or other metal to be treated. In the presence of ferrous ions from the iron, steel or other metal, the slurry reacts to form iron phosphates which form grains chemically bonded onto the surface of the steel.

  20. Electrochemical noise measurements of stainless steel in high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Arganis-Juarez, C.R. [Instituto Nacional de Investigaciones Nucleares Km. 36.5, Carretera Federal Mexico-Toluca, Municipio de Ocoyoacac, C.P. 52045, Estado de Mexico (Mexico); Malo, J.M. [Instituto de Investigaciones Electricas Av. Reforma 113, Col. Palmira, C.P. 62490, Cuernavaca, Morelos (Mexico)], E-mail: jmmalo@iie.org.mx; Uruchurtu, J. [Centro de Investigaciones en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, C.P. 62210, Cuernavaca, Morelos (Mexico)

    2007-12-15

    Corrosion in a high purity aqueous environment simulating a boiling water reactor (BWR) is addressed in this work. This condition necessitates autoclave experiments under high pressure and temperature. Long-term electrochemical noise measurements were explored as a mean to detect and monitor stress corrosion cracking phenomenon. An experimental set up, designed to insulate the working electrode from external interference, made possible to detect and monitor stress corrosion cracking in slow strain rate tests for sensitized and solution annealed 304 stainless steel at 288 {sup o}C. Time-series analysis showed variations in the signature of the current density series due to transgranular stress corrosion cracking (TGSCC) and intergranular stress corrosion cracking (IGSCC)

  1. An effective route for the room temperature formation of Pd coatings on multiwalled carbon nanotubes in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeong Joon [Dept. of Chemistry, Chungnam National University, Daejeon (Korea, Republic of); Lee, Im Kyu; Song, Jae Hee [Dept. of Chemistry, Sunc hon National University, Suncheon (Korea, Republic of)

    2016-10-15

    We present an easy one-pot synthesis route for the production of palladium nanoparticles and multiwalled carbon nanotubes (MWCNTs)-supported Pd-nanomaterial composites by a simple proton beam irradiation process in an aqueous solution at room temperature. Pristine and surface-modified MWCNTs were used to prepare MWCNT–Pd hybrids. Pd nanoparticles on the surfaces of MWCNTs were produced in situ in an aqueous solution without the addition of any harsh reducing agent. Pristine and thiolated MWCNTs were both densely decorated with spherical Pd nanoparticles and eventually Pd nanowire formation on MWCNTs was realized when reaction times exceeded 60 min. The thicknesses of Pd coatings on MWCNT surfaces were controlled by varying the concentration of MWCNTs in the reaction mixture. MWCNT-Pd composites were characterized by time-resolved transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray spectroscopy, and the results obtained showed that Pd coatings were continuous, and resulted in a MWCNT-supported Pd nanowire structure.

  2. High-temperature Corrosion of AlCrTiSiN Film in Ar-1%SO{sub 2} Gas

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Poonam; Lee, Dong Bok [Sungkyunkwan University, Suwon (Korea, Republic of); Kwon, Sik Chol [Chungbuk National University, Cheongju (Korea, Republic of); Lin, Yue; Zhang, Shihong [Anhui University of Technology, Maanshan (China)

    2017-04-15

    An AlCrTiSiN film composed of 31Al-15Cr-1.7Ti-0.5Si-51.8N (at%) was deposited on a steel substrate by arc ion plating to a thickness of 1 μm. It consisted of nano crystalline hcp-AlN and fcc-CrN. Its corrosion behavior in Ar-1%SO{sub 2} gas at 800 ℃ for 5-50 h was studied. The resulting scales consisted primarily of Al{sub 2}O{sub 3} and Cr{sub 2}O{sub 3}, which effectively suppressed the corrosion. No sulfides formed, because Al and Cr oxidized competitively from the surface. The film was primarily corroded by the inward diffusion of oxygen and a much smaller amount of sulfur.

  3. Novel High Strength Ceria-Zirconia Toughened Alumina Ceramic with Superior High Temperature Corrosion and Erosion Resistance. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Giulio, R.; Butcher, K.

    2004-01-13

    Composite CeTZP/A1{sub 2}O{sub 3} (CeZTA) foams were developed and tested to determine their suitability as particulate filters in hot gaseous conditions generated by coal combustion in electric power plants. Exposure to these extreme corrosive conditions did not cause significant degradation in strength. Superior properties of these foams suggests they could be used for a variety of applications in environment, energy and chemical fields.

  4. Development of Self-Powered Wireless-Ready High Temperature Electrochemical Sensors for In-Situ Corrosion Monitoring for Boiler Tubes in Next Generation Coal-based Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xingbo [West Virginia Univ., Morgantown, WV (United States)

    2015-06-30

    The key innovation of this project is the synergy of the high temperature sensor technology based on the science of electrochemical measurement and state-of-the-art wireless communication technology. A novel self-powered wireless high temperature electrochemical sensor system has been developed for coal-fired boilers used for power generation. An initial prototype of the in-situ sensor demonstrated the capability of the wireless communication system in the laboratory and in a pilot plant (Industrial USC Boiler Setting) environment to acquire electrochemical potential and current signals during the corrosion process. Uniform and localized under-coal ash deposit corrosion behavior of Inconel 740 superalloy has been studied at different simulated coal ash hot corrosion environments using the developed sensor. Two typical potential noise patterns were found to correlate with the oxidation and sulfidation stages in the hot coal ash corrosion process. Two characteristic current noise patterns indicate the extent of the corrosion. There was a good correlation between the responses of electrochemical test data and the results from corroded surface analysis. Wireless electrochemical potential and current noise signals from a simulated coal ash hot corrosion process were concurrently transmitted and recorded. The results from the performance evaluation of the sensor confirm a high accuracy in the thermodynamic and kinetic response represented by the electrochemical noise and impedance test data.

  5. Experimental and numerical study on effects of airflow and aqueous ammonium solution temperature on ammonia mass transfer coefficient.

    Science.gov (United States)

    Rong, Li; Nielsen, Peter V; Zhang, Guoqiang

    2010-04-01

    This paper reports the results of an investigation, based on fundamental fluid dynamics and mass transfer theory, carried out to obtain a general understanding of ammonia mass transfer from an emission surface. The effects of airflow and aqueous ammonium solution temperature on ammonia mass transfer are investigated by using computational fluid dynamics (CFD) modeling and by a mechanism modeling using dissociation constant and Henry's constant models based on the parameters measured in the experiments performed in a wind tunnel. The validated CFD model by experimental data is used to investigate the surface concentration distribution and mass transfer coefficient at different temperatures and velocities for which the Reynolds number is from 1.36 x 10(4) to 5.43 x 10(4) (based on wind tunnel length). The surface concentration increases as velocity decreases and varies greatly along the airflow direction on the emission surface. The average mass transfer coefficient increases with higher velocity and turbulence intensity. However, the mass transfer coefficient estimated by CFD simulation is consistently larger than the calculated one by the method using dissociation constant and Henry's constant models. In addition, the results show that the liquid-air temperature difference has little impact on the simulated mass transfer coefficient by CFD modeling, whereas the mass transfer coefficient increases with higher liquid temperature using the other method under the conditions that the liquid temperature is lower than the air temperature. Although there are differences of mass transfer coefficients between these two methods, the mass transfer coefficients determined by these two methods are significantly related.

  6. Relationship between Microstructure and Corrosion Behavior of Martensitic High Nitrogen Stainless Steel 30Cr15Mo1N at Different Austenitizing Temperatures.

    Science.gov (United States)

    Jiang, Zhouhua; Feng, Hao; Li, Huabing; Zhu, Hongchun; Zhang, Shucai; Zhang, Binbin; Han, Yu; Zhang, Tao; Xu, Dake

    2017-07-27

    The relationship between microstructure and corrosion behavior of martensitic high nitrogen stainless steel 30Cr15Mo1N at different austenitizing temperatures was investigated by microscopy observation, electrochemical measurement, X-ray photoelectron spectroscopy analysis and immersion testing. The results indicated that finer Cr-rich M₂N dispersed more homogeneously than coarse M 23 C₆, and the fractions of M 23 C₆ and M₂N both decreased with increasing austenitizing temperature. The Cr-depleted zone around M 23 C₆ was wider and its minimum Cr concentration was lower than M₂N. The metastable pits initiated preferentially around coarse M 23 C₆ which induced severer Cr-depletion, and the pit growth followed the power law. The increasing of austenitizing temperature induced fewer metastable pit initiation sites, more uniform element distribution and higher contents of Cr, Mo and N in the matrix. In addition, the passive film thickened and Cr₂O₃, Cr 3+ and CrN enriched with increasing austenitizing temperature, which enhanced the stability of the passive film and repassivation ability of pits. Therefore, as austenitizing temperature increased, the metastable and stable pitting potentials increased and pit growth rate decreased, revealing less susceptible metastable pit initiation, larger repassivation tendency and higher corrosion resistance. The determining factor of pitting potentials could be divided into three stages: dissolution of M 23 C₆ (below 1000 °C), dissolution of M₂N (from 1000 to 1050 °C) and existence of a few undissolved precipitates and non-metallic inclusions (above 1050 °C).

  7. Effect of ceramic conversion treatments on the surface damage and nickel ion release of NiTi alloys under fretting corrosion conditions.

    Science.gov (United States)

    Dong, H; Ju, X; Yang, H; Qian, L; Zhou, Z

    2008-02-01

    Recent researches have demonstrated that surface modification can improve the fretting wear resistance of NiTi alloys in air or enhance their aqueous corrosion resistance without fretting. However, little is known about the behaviour of surface engineered NiTi under fretting corrosion conditions. This is important for such body implants as orthodontic arch wires and orthopedic bone fixation devices because they need to withstand the combined attack of corrosion from body fluid and mechanical fretting. In this study, a NiTi alloy was ceramic conversion (CC) treated at 400 and 650 degrees C. The effect of the surface treatment on the fretting corrosion behaviour of NiTi alloy was investigated using fretting corrosion tests in the Ringer's solution. The experimental results have shown that the CC treatment can convert the surface of NiTi into a TiO2 layer, which can effectively improve the fretting corrosion resistance of NiTi alloy and significantly reduce Ni ion release into the Ringer's solution. Detailed SEM observations revealed that the untreated samples were severely damaged by adhesion and delamination; the high temperature (HT) (650 degrees C/1 h) treated samples were damaged mainly by spallation and adhesion; and the low temperature (LT) (400 degrees C/50 h) treated samples were characterised by mild abrasion. Mild oxidation and corrosion were also observed for all three types of samples tested under fretting corrosion conditions.

  8. Efficient "light-soaking"-free inverted organic solar cells with aqueous solution processed low-temperature ZnO electron extraction layers.

    Science.gov (United States)

    Wei, Wei; Zhang, Chunfu; Chen, Dazheng; Wang, Zhizhe; Zhu, Chunxiang; Zhang, Jincheng; Lu, Xiaoli; Hao, Yue

    2013-12-26

    Low-temperature processes are unremittingly pursued in the fabrication of organic solar cells. The paper reports that the highly efficient and "light-soaking"-free inverted organic solar cell can be achieved by using ZnO thin films processed from the aqueous solution method at a low temperature. The inverted organic solar with an aqueous-processed ZnO thin film annealed at 150 °C shows an efficiency of 3.79%. Even when annealed at a temperature as low as 80 °C, the device still shows an efficiency of 3.71%. With the proper annealing temperature of 80 °C, the flexible device, which shows an efficiency of 3.56%, is fabricated on PET. This flexible device still keeps the efficiency above 3.40% after bent for 1000 times with a curvature radius of 50 mm. In contrast, a low annealing temperature leads to an inferior device performance when the ZnO thin film is processed from the widely used sol-gel method. The device with sol-gel processed ZnO annealed at 150 °C only shows a PCE of 1.3%. Furthermore, the device shows a strong "light-soaking" effect, which is not observed in the device containing an aqueous-processed ZnO thin film. Our results suggest that the adopted aqueous solution method is a more efficient low temperature technique, compared with the sol-gel method.

  9. Synthesis of barium titanate powders by low-temperature aqueous synthesis using a new segmented flow tubular reactor

    Energy Technology Data Exchange (ETDEWEB)

    Bowen, P.; Donnet, M. [Swiss Federal Inst. of Technology, Lausanne (Switzerland). Materials Science and Eng. Dept.; Testino, A.; Viviani, M.; Buscaglia, M.T.; Buscaglia, V. [National Research Council, Genoa (Italy). Inst. for Physical Chemistry of Materials; Nanni, P. [Chemical and Process Engineering Dept. - Univ. of Genoa (Italy)

    2002-07-01

    Barium titanate powders have been synthesised using a low temperature aqueous synthesis (LTAS) method in both batch and Segmented Flow Tubular Reactors. For similar stoichiometries the SFTR powder shows a much lower degree of aggregation with 80% particles <100 nm for the SFTR and only 57% <100 nm for the batch case. Specific surface areas for the SFTR powder are also higher at around 50 m{sup 2}/g compared to 38 m{sup 2}/g for the batch powders indicative of primary particle sizes of 24 nm (SFTR) and 31 nm (batch). After freeze drying, redispersion and slip casting the SFTR powder gives improved sintered densities (95.5 from 93.25%) the sintered microstructures are very similar. (orig.)

  10. Surface aspects of pitting and stress corrosion cracking

    Science.gov (United States)

    Truhan, J. S., Jr.; Hehemann, R. F.

    1977-01-01

    The pitting and stress corrosion cracking of a stable austenitic stainless steel in aqueous chloride environments were investigated using a secondary ion mass spectrometer as the primary experimental technique. The surface concentration of hydrogen, oxygen, the hydroxide, and chloride ion, magnesium or sodium, chromium and nickel were measured as a function of potential in both aqueous sodium chloride and magnesium chloride environments at room temperature and boiling temperatures. It was found that, under anodic conditions, a sharp increase in the chloride concentration was observed to occur for all environmental conditions. The increase may be associated with the formation of an iron chloride complex. Higher localized chloride concentrations at pits and cracks were also detected with an electron microprobe.

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

    Energy Technology Data Exchange (ETDEWEB)

    Beauvy, M.; Berthoud, G.; Defranceschi, M.; Ducros, G.; Feron, D.; Guerin, Y.; Latge, C.; Limoge, Y.; Madic, C.; Santarini, G.; Seiler, J.M.; Vernaz, E.; Richet, C.

    2010-07-01

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

  12. Strand break formation in plasmid DNA irradiated in aqueous solution: effect of medium temperature and hydroxyl radical scavenger concentration.

    Science.gov (United States)

    Tomita, H; Kai, M; Kusama, T; Aoki, Y

    1995-03-01

    Plasmid pBR322 DNA (4363 base pairs) in aerobic aqueous solution was irradiated with 60Co gamma-radiation. The change of diffusion coefficients (D) of chemical species, rate constants (k) of radical-DNA interaction and solubilities of O2 in water cannot be ignored when a temperature varies more than a few tens of centigrade. It is important to examine the variation of the yields of DNA strand breaks as a function of temperature in order to analyze the mechanisms of DNA strand breaks from the chemical point of view. Hence, we observed the change of the yield of strand breaks with temperatures between -20 and 42 degrees C by agarose gel electrophoresis. We also observed the change of the yield of strand breaks with the concentration of OH scavenger (Tris) from 1 mmol dm-3 to 100 mmol dm-3 and summarized it with previous experiments. This summarization indicated that the order of the lifetime of OH radical in cellular environment is several nanosecond. This value is consistent with the measurement of the lifetime of 8.7 nanosecond for OH radical in mammalian cell (Roots, R. and Okada, S. (1975) Radiat. Res. 64, 306-320).

  13. A spectrophotometric study of Am(III) complexation with nitrate in aqueous solution at elevated temperatures.

    Science.gov (United States)

    Tian, Guoxin; Shuh, David K

    2014-10-21

    The complexation of americium(iii) with nitrate was studied at temperatures from 10 to 85 °C in 1 M HNO3-HClO4 by spectrophotometry. The 1 : 1 complex species, AmNO3(2+), was identified and the stability constants were calculated from the absorption spectra recorded for titrations at several temperatures. Specific ion interaction theory (SIT) was used for ionic strength corrections to obtain the stability constants of AmNO3(2+) at infinite dilution and variable temperatures. The absorption spectra of Am(iii) in diluted HClO4 were also reviewed, and the molar absorptivity of Am(iii) at around 503 nm and 813 nm was re-calibrated by titrations with standardized DTPA solutions to determine the concentration of Am(iii).

  14. Aqueous solutions of calcium ions: hydration numbers and the effect of temperature.

    Science.gov (United States)

    Zavitsas, Andreas A

    2005-11-03

    Hydration numbers of calcium ions are determined from extensive measurements of colligative properties of water solutions of calcium salts. The hydration numbers reported refer to the average number of water molecules that are bound sufficiently strongly to calcium ions so as to be removed from the solvent and become part of the solute. Contrary to common descriptions of deviations from ideal behavior for concentrated solutions, ideal behavior is demonstrated when mole fractions are calculated by taking account of such bound water. Measurements over wide concentration and temperature ranges are used to obtain the effect of temperature on the average hydration number of Ca(2+). Freezing point depression measurements yield a hydration number of 12.0 +/- 0.8. Boiling point elevations yield 6.7 +/- 0.6. Consistent with this, vapor pressure measurements from 0 to 200 degrees C show a gradual decrease in hydration number with increasing temperature, with a value of 5.0 at 200 degrees C.

  15. (Ultra)fast catalyst-free macromolecular conjugation in aqueous environment at ambient temperature.

    Science.gov (United States)

    Glassner, Mathias; Delaittre, Guillaume; Kaupp, Michael; Blinco, James P; Barner-Kowollik, Christopher

    2012-05-02

    Tailor-made water-soluble macromolecules, including a glycopolymer, obtained by living/controlled RAFT-mediated polymerization are demonstrated to react in water with diene-functionalized poly(ethylene glycol)s without pre- or post-functionalization steps or the need for a catalyst at ambient temperature. As previously observed in organic solvents, hetero-Diels-Alder (HDA) conjugations reached quantitative conversion within minutes when cyclopentadienyl moieties were involved. However, while catalysts and elevated temperatures were previously necessary for open-chain diene conjugation, additive-free HDA cycloadditions occur in water within a few hours at ambient temperature. Experimental evidence for efficient conjugations is provided via unambiguous ESI-MS, UV/vis, NMR, and SEC data. © 2012 American Chemical Society

  16. Ion pair formation in copper sulfate aqueous solutions at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Mendez De Leo, Lucila P. [Unidad de Actividad Quimica, Comision Nacional de Energia, Avenida del Libertador 8250, 1429 Ciudad de Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, Universidad Nacional General San Martin, Alem 3901, 1653 Villa Ballester (Argentina); Bianchi, Hugo L. [Unidad de Actividad Quimica, Comision Nacional de Energia, Avenida del Libertador 8250, 1429 Ciudad de Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, Universidad Nacional General San Martin, Alem 3901, 1653 Villa Ballester (Argentina); Fernandez-Prini, Roberto [Unidad de Actividad Quimica, Comision Nacional de Energia, Avenida del Libertador 8250, 1429 Ciudad de Buenos Aires (Argentina) and INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon II, 1428 Ciudad de Buenos Aires (Argentina)]. E-mail: rfprini@cnea.gov.ar

    2005-05-15

    Ionic association between Cu{sup 2+}(aq) and SO42-(aq) has been studied in the temperature range (298 to 473) K using a spectrophotometric technique. Experiments were designed to minimize the contribution of other protolytic equilibria in solution. The values of the ionic association equilibrium constant at different temperatures and pressures were fitted to an appropriate equation that allows the calculation of the thermodynamic quantities for states close to the saturation line. Using Bjerrum's model for ionic association evidence for two ion pair populations was obtained. The process of ion pairing is discussed and a possibility to reconcile the continuum model (Bjerrum) with molecular simulation results is suggested.

  17. Corrosion inhibition..

    African Journals Online (AJOL)

    ABSTRACT. The corrosion inhibition of carbon steel in 3% de-aerated NaCl acidic solution with amine—fatty acid corrosion inhibitor, KI384, .... reduction reaction causing no decrease in the limiting current density of that process. On the .... value when compared to the base solution. This provides a support to the physical ...

  18. Corrosion Engineering.

    Science.gov (United States)

    White, Charles V.

    A description is provided for a Corrosion and Corrosion Control course offered in the Continuing Engineering Education Program at the General Motors Institute (GMI). GMI is a small cooperative engineering school of approximately 2,000 students who alternate between six-week periods of academic study and six weeks of related work experience in…

  19. Corrosion sensor

    Science.gov (United States)

    Glass, Robert S.; Clarke, Jr., Willis L.; Ciarlo, Dino R.

    1994-01-01

    A corrosion sensor array incorporating individual elements for measuring various elements and ions, such as chloride, sulfide, copper, hydrogen (pH), etc. and elements for evaluating the instantaneous corrosion properties of structural materials. The exact combination and number of elements measured or monitored would depend upon the environmental conditions and materials used which are subject to corrosive effects. Such a corrosion monitoring system embedded in or mounted on a structure exposed to the environment would serve as an early warning system for the onset of severe corrosion problems for the structure, thus providing a safety factor as well as economic factors. The sensor array is accessed to an electronics/computational system, which provides a means for data collection and analysis.

  20. Electrochemical corrosion testing of metal waste forms

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-12-14

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

  1. Corrosion of aluminum clad spent nuclear fuel in the 70 ton cask during transfer from L area to H-canyon

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J. I. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-08-01

    Aluminum-clad spent nuclear fuel will be transported for processing in the 70-ton nuclear fuel element cask from L Basin to H-canyon. During transport these fuels would be expected to experience high temperature aqueous corrosion from the residual L Basin water that will be present in the cask. Cladding corrosion losses during transport were calculated for material test reactor (MTR) and high flux isotope reactors (HFIR) fuels using literature and site information on aqueous corrosion at a range of time/temperature conditions. Calculations of the cladding corrosion loss were based on Arrhenius relationships developed for aluminum alloys typical of cladding material with the primary assumption that an adherent passive film does not form to retard the initial corrosion rate. For MTR fuels a cladding thickness loss of 33% was found after 1 year in the cask with a maximum temperature of 263 °C. HFIR fuels showed a thickness loss of only 6% after 1 year at a maximum temperature of 180 °C. These losses are not expected to impact the overall confinement function of the aluminum cladding.

  2. Corrosion of aluminum clad spent nuclear fuel in the 70 ton cask during transfer from L area to H-canyon

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J. I. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-08-31

    Aluminum-clad spent nuclear fuel will be transported for processing in the 70-ton nuclear fuel element cask from L Basin to H-canyon. During transport these fuels would be expected to experience high temperature aqueous corrosion from the residual L Basin water that will be present in the cask. Cladding corrosion losses during transport were calculated for material test reactor (MTR) and high flux isotope reactors (HFIR) fuels using literature and site information on aqueous corrosion at a range of time/temperature conditions. Calculations of the cladding corrosion loss were based on Arrhenius relationships developed for aluminum alloys typical of cladding material with the primary assumption that an adherent passive film does not form to retard the initial corrosion rate. For MTR fuels a cladding thickness loss of 33 % was found after 1 year in the cask with a maximum temperature of 263 °C. HFIR fuels showed a thickness loss of only 6% after 1 year at a maximum temperature of 180 °C. These losses are not expected to impact the overall confinement function of the aluminum cladding.

  3. CORROSION OF ALUMINUM CLAD SPENT NUCLEAR FUEL IN THE 70 TON CASK DURING TRANSFER FROM L AREA TO H-CANYON

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J.

    2014-06-01

    Aluminum-clad spent nuclear fuel will be transported for processing in the 70-ton nuclear fuel element cask from L Basin to H-canyon. During transport these fuels would be expected to experience high temperature aqueous corrosion from the residual L Basin water that will be present in the cask. Cladding corrosion losses during transport were calculated for material test reactor (MTR) and high flux isotope reactors (HFIR) fuels using literature and site information on aqueous corrosion at a range of time/temperature conditions. Calculations of the cladding corrosion loss were based on Arrhenius relationships developed for aluminum alloys typical of cladding material with the primary assumption that an adherent passive film does not form to retard the initial corrosion rate. For MTR fuels a cladding thickness loss of 33 % was found after 1 year in the cask with a maximum temperature of 260 {degrees}C. HFIR fuels showed a thickness loss of only 6% after 1 year at a maximum temperature of 180 {degrees}C. These losses are not expected to impact the overall confinement function of the aluminum cladding.

  4. Pitting corrosion of copper. An equilibrium - mass transport study

    Energy Technology Data Exchange (ETDEWEB)

    Taxen, C.

    1996-11-01

    A mathematical model for the propagation of corrosion pits on copper is described. The model is used to predict the potentials below which copper is immune to pitting. The criteria used for immunity against pitting is that the volume of the cuprous oxide formed at the site of the metal oxidation at the bottom of a corrosion pit must be smaller than the volume of the oxidised metal. Equal volumes would give a complete coverage of the metal in a pit by adherent cuprous oxide and propagation would not be possible. For potentials where copper is not immune to pitting an estimate of the maximum growth rate is given. The model uses equilibrium data and diffusion coefficients and calculates the stationary concentration profiles from the bulk water outside a corrosion pit to the site of the metal dissolution at the bottom a corrosion pit. Precipitation of oxides as well as of basic salts of copper is considered. A total of 26 aqueous species are considered in waters with compositions ranging from those of tap waters to that of sea water. Calculations are made for the temperatures 25 deg C and 75 deg C. 38 refs, 60 figs, 17 tabs

  5. Effect of Al Hot-Dipping on High-Temperature Corrosion of Carbon Steel in N2/0.1% H2S Gas

    Directory of Open Access Journals (Sweden)

    Muhammad Ali Abro

    2016-02-01

    Full Text Available High-temperature corrosion of carbon steel in N2/0.1% H2S mixed gas at 600–800 °C for 50–100 h was studied after hot-dipping in the aluminum molten bath. Hot-dipping resulted in the formation of the Al topcoat and the Al-Fe alloy layer firmly adhered on the substrate. The Al-Fe alloy layer consisted primarily of a wide, tongue-like Al5Fe2 layer and narrow Al3Fe layer. When corroded at 800 °C for 100 h, the Al topcoat partially oxidized to the protective but non-adherent α-Al2O3 layer, and the interdiffusion converted the Al-Fe alloy layer to an (Al13Fe4, AlFe3-mixed layer. The interdiffusion also lowered the microhardness of the hot-dipped steel. The α-Al2O3 layer formed on the hot-dipped steel protected the carbon steel against corrosion. Without the Al hot-dipping, the carbon steel failed by forming a thick, fragile, and non-protective FeS scale.

  6. Conformational relaxation dynamics of a poly(N-isopropylacrylamide) aqueous solution measured using the laser temperature jump transient grating method.

    Science.gov (United States)

    Inoue, Hayato; Katayama, Kenji; Iwai, Kaoru; Miura, Atsushi; Masuhara, Hiroshi

    2012-04-28

    We observed phase transition and phase relaxation processes of a poly(N-isopropylacrylamide) (PNIPAM) aqueous solution using the heterodyne transient grating (HD-TG) method combined with the laser temperature jump technique. The sample temperature was instantaneously raised by about 1.0 K after irradiation of a pump pulse to crystal violet (CV) molecules for heating, and the phase transition was induced for the sample with an initial temperature just below the lower critical solution temperature (LCST); the following phase relaxation dynamics was observed. Turbidity relaxation was observed in both the turbidity and HD-TG responses, while another relaxation process was observed only in the HD-TG response, namely via the refractive index change. It is suggested that this response is due to formation of globule molecules or their assemblies since they would have nothing to do with turbidity change but would affect the refractive index, which is dependent on the molar volume of a chemical species. Furthermore, the grating spacing dependence of the HD-TG responses suggests that the response was caused by the counter propagating diffusion of the coil molecules as a reactant species and the globule molecules as a product species and the lifetime of the globule molecules ranged from 1.5 to 5 seconds. Thus, we conclude that the turbidity reflects the dynamics of aggregate conditions, not molecular conditions. The coil and globule sizes were estimated from the obtained diffusion coefficient. The sizes of the coil molecules did not change at the initial temperatures below the LCST but increased sharply as it approaches LCST. We propose that the coil-state molecules associate due to hydrophobic interaction when the initial temperature was higher than LCST minus 0.5 K and that the globule-state molecules generated from the coil-state molecules showed a similar trend in temperature. The phase transition was also induced by heating under a microscope, and the relaxation process

  7. The role of the temperature in the morphology and properties of zinc oxide structures obtained by electrosynthesis in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Jaffry, U.; Mazario, E. [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada, 28049 Madrid (Spain); Lemus, J. [CICECO – Aveiro Institute of Materials, Chemistry Department, University of Aveiro, 3810-193 Aveiro (Portugal); Rivero, M.; Muñoz-Bonilla, A. [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada, 28049 Madrid (Spain); Herrasti, P., E-mail: pilar.herrasti@uam.es [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada, 28049 Madrid (Spain)

    2016-09-15

    Herein, ZnO micro and nanostructures were synthesized by an electrochemical method in aqueous solution employing NaCl as the electrolyte. Different parameters influencing the synthesis process, i.e. current intensity, reaction time and temperature, were investigated. From this, it was concluded that the productivity of the reaction increases with longer reaction time, whereas the use of higher current intensity augments the specific energy consumption. On the other hand, the increase in temperature seems to exert a negative effect. The characterization of the resulting materials by scanning electron microscopy, X-ray diffraction and thermogravimetric analysis demonstrated that a mixture of Zn(OH){sub 2} and ZnO crystalline structures is formed directly from the synthesis procedure. The content of Zn(OH){sub 2} phase in the sample decreases as the temperature of the synthesis increases, this fact indicates that the low productivity obtained at higher temperatures is related to the nature of the resulting material. Thermal annealing of the samples containing both phases prepared following synthesis allows the phase transformation from Zn(OH){sub 2} to pure ZnO structures. The band gap energies of the ZnO materials were determined by diffuse reflectance measurements according to the Kubelka Munk theory, revealing low values in all the cases which were highly dependent on the size of crystals within the materials. The photocatalytic properties of the pure ZnO samples post calcination were investigated by the decomposition of an organic dye under UV light irradiation. The results show the beneficial photocatalytic properties of the samples that had undergone calcination, these were superior in comparison to those prepared at room temperature which mainly consisted of Zn(OH){sub 2}. - Highlights: • ZnO micro and nanostructures were synthesized by an electrochemical method. • Increasing the applied current and synthesis temperature augments the specific energy

  8. Calcium and strontium isotope fractionation during precipitation from aqueous solutions as a function of temperature and reaction rate; II. Aragonite

    Science.gov (United States)

    AlKhatib, Mahmoud; Eisenhauer, Anton

    2017-07-01

    In order to study Strontium (Sr) partitioning and isotope fractionation of Sr and Calcium (Ca) in aragonite we performed precipitation experiments decoupling temperature and precipitation rates (R∗, μmol/m2 h) in the interval of about 2.3-4.5 μmol/m2 h. Aragonite is the only pure solid phase precipitated from a stirred solutions exposed to an atmosphere of NH3 and CO2 gases throughout the spontaneous decomposition of (NH4)2CO3. The order of reaction with respect to Ca ions is one and independent of temperature. However, the order of reaction with respect to the dissolved inorganic carbon (DIC) is temperature dependent and decreases from three via two to one as temperature increases from 12.5 and 25.0 to 37.5 °C, respectively. Strontium distribution coefficient (DSr) increases with decreasing temperature. However, R∗ responds differently depending on the initial Sr/Ca concentration and temperature: at 37.5 °C DSr increase as a function of increasing R∗ but decrease for 12.5 and 25 °C. Not seen at 12.5 and 37.5 °C but at 25 °C the DSr-R∗ gradient is also changing sign depending on the initial Sr/Ca ratio. Magnesium (Mg) adsorption coefficient between aragonite and aqueous solution (DMg) decreases with temperature but increases with R∗ in the range of 2.4-3.8 μmol/m2 h. Strontium isotope fractionation (Δ88/86Sraragonite-aq) follows the kinetic type of fractionation and become increasingly negative as a function of R∗ for all temperatures. In contrast Ca isotope fractionation (Δ44/40Caaragonite-aq) shows a different behavior than the Sr isotopes. At low temperatures (12.5 and 25 °C) Ca isotope fractionation (Δ44/40Caaragonite-aq) becomes positive as a function of R∗. In contrast, at 37.5 °C and as a function of increasing R∗ the Δ44/40Caaragonite-aq show a Sr type like behavior and becomes increasingly negative. Concerning both the discrepant behavior of DSr as a function of temperature as well as for the Ca isotope fractionation as a

  9. High Temperature Corrosion and Characterization Studies in Flux Cored Arc Welded 2.25Cr-1Mo Power Plant Steel

    Science.gov (United States)

    Kumaresh Babu, S. P.; Natarajan, S.

    2010-07-01

    Higher productivity is registered with Flux cored arc welding (FCAW) process in many applications. Further, it combines the characteristics of shielded metal arc welding (SMAW), gas metal arc welding (GMAW), and submerged arc welding (SAW) processes. This article describes the experimental work carried out to evaluate and compare corrosion and its inhibition in SA 387 Gr.22 (2.25Cr-1Mo) steel weldments prepared by FCAW process with four different heat inputs exposed to hydrochloric acid medium at 0.1, 0.5, and 1.0 M concentrations. The parent metal, weld metal, and heat-affected zone are chosen as regions of exposure for the study carried out at 100 °C. Electrochemical polarization techniques such as Tafel line extrapolation (Tafel) and linear polarization resistance (LPR) have been used to measure the corrosion current. The role of hexamine and mixed inhibitor (thiourea + hexamine in 0.5 M HCl), each at 100 ppm concentration is studied in these experiments. Microstructural observation, hardness survey, surface characterization, and morphology using scanning electron microscope (SEM) and x-ray diffraction (XRD) have been made on samples to highlight the nature and extent of film formation. The film is found to contain Fe2Si, FeSi2, FeMn3, Fe7Mo3, Fe3O4, FeO, FeCr, AlO7Fe3SiO3, and KFe4Mn77Si19.

  10. Combined Effect of Temperature and pKa on the Kinetics of Absorption of Carbon Dioxide in Aqueous Alkanolamine and Carbonate Solutions with Carbonic Anhydrase

    NARCIS (Netherlands)

    Penders-Van Elk, Nathalie J M C; Oversteegen, S. Martijn; Versteeg, Geert F.

    2016-01-01

    In present work the absorption of carbon dioxide in aqueous N-methyldiethanolamine, N,N-dimethylethanolamine, and triisopropanolamine solutions with and without the enzyme carbonic anhydrase has been studied in a stirred cell reactor at temperatures varying between 278 and 313 K, at an alkanolamine

  11. Temperature dependence of hydroxyl radical reactions with chloramine species in aqueous solution.

    Science.gov (United States)

    Gleason, Jamie M; McKay, Garrett; Ishida, Kenneth P; Mezyk, Stephen P

    2017-11-01

    The absolute temperature-dependent kinetics for the reaction between hydroxyl radicals and the chloramine water disinfectant species monochloramine (NH2Cl), as well as dichloramine (NHCl2) and trichloramine (NCl3), have been determined using electron pulse radiolysis and transient absorption spectroscopy. These radical reaction rate constants were fast, with values of 6.06 × 108, 2.57 × 108, and 1.67 × 108 M-1 s-1 at 25 °C for NH2Cl, NHCl2, and NCl3, respectively. The corresponding temperature dependence of these reaction rate constants, measured over the range 10-40 °C, is well-described by the transformed Arrhenius equations:giving activation energies of 8.57 ± 0.58, 6.11 ± 0.40, and 5.77 ± 0.72 kJ mol-1 for these three chloramines, respectively. These data will aid water utilities in predicting hydroxyl radical partitioning and chemical contaminant removal efficiencies under real-world advanced oxidation process treatment conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Development of novel protective high temperature coatings on heat exchanger steels and their corrosion resistance in simulated coal firing environment; Developpement de revetements pour les aciers d'echangeurs thermiques et amelioration de leur resistance a la corrosion en environnement simulant les fumees de combustion et de charbon

    Energy Technology Data Exchange (ETDEWEB)

    Rohr, V.

    2005-10-15

    Improving the efficiencies of thermal power plants requires an increase of the operating temperatures and thus of the corrosion resistance of heat exchanger materials. Therefore, the present study aimed at developing protective coatings using the pack cementation process. Two types of heat exchanger steels were investigated: a 17% Cr-13% Ni austenitic steel and three ferritic-martensitic steels with 9 (P91 and P92) and 12% Cr (HCM12A). The austenitic steel was successfully aluminized at 950 C. For the ferritic-martensitic steels, the pack cementation temperature was decreased down to 650 C, in order to maintain their initial microstructure. Two types of aluminides, made of Fe{sub 2}Al{sub 5} and FeAl, were developed. A mechanism of the coating formation at low temperature is proposed. Furthermore, combining the pack cementation with the conventional heat treatment of P91 allowed to take benefit of higher temperatures for the deposition of a two-step Cr+Al coating. The corrosion resistance of coated and uncoated steels is compared in simulated coal firing environment for durations up to 2000 h between 650 and 700 C. It is shown that the coatings offer a significant corrosion protection and, thus, an increase of the component lifetime. Finally, the performance of coated 9-12% Cr steels is no longer limited by corrosion but by interdiffusion between the coating and the substrate. (author)

  13. High-performance zno transistors processed via an aqueous carbon-free metal oxide precursor route at temperatures between 80-180 °c

    KAUST Repository

    Lin, Yenhung

    2013-06-25

    An aqueous and carbon-free metal-oxide precursor route is used in combination with a UV irradiation-assisted low-temperature conversion method to fabricate low-voltage ZnO transistors with electron mobilities exceeding 10 cm2/Vs at temperatures <180°C. Because of its low temperature requirements the method allows processing of high-performance transistors onto temperature sensitive substrates such as plastic. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Hydrogen bond network relaxation in aqueous polyelectrolyte solutions: the effect of temperature

    Science.gov (United States)

    Sarti, S.; Truzzolillo, D.; Bordi, F.

    2012-07-01

    Dielectric spectroscopy data over the range 100 MHz-40 GHz allow for a reliable analysis of two of the major relaxation phenomena for polyelectrolytes (PE) in water. Within this range, the dielectric relaxation of pure water is dominated by a near-Debye process at ν = 18.5 GHz corresponding to a relaxation time of τ = 8.4 ps at 25 °C. This mode is commonly attributed to the cooperative relaxation specific to liquids forming a hydrogen bond network (HBN) and arising from long range H-bond-mediated dipole-dipole interactions. The presence of charged polymers in water partially modifies the dielectric characteristics of the orientational water molecule relaxation due to a change of the dielectric constant of water surrounding the charges on the polyion chain. We report experimental results on the effect of the presence of a standard flexible polyelectrolyte (sodium polyacrylate) on the HBN relaxation in water for different temperatures, showing that the HBN relaxation time does not change by increasing the polyelectrolyte density in water, even if relatively high concentrations are reached (0.02 monomol l-1 ≤ C ≤ 0.4 monomol l-1). We also find that the effect of PE addition on the HBN relaxation is not even a broadening of its distribution, rather a decrease of the spectral weight that goes beyond the pure volume fraction effect. This extra decrease is larger at low T and less evident at high T, supporting the idea that the correlation length of the water is less affected by the presence of charged flexible chains at high temperatures.

  15. Review of state-of-the-art of solar collector corrosion processes. Task 1 of solar collector studies for solar heating and cooling applications. Final technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Clifford, J E; Diegle, R B

    1980-04-11

    The state-of-the-art of solar collector corrosion processes is reviewed, and Task 1 of a current research program on use of aqueous heat transfer fluids for solar heating and cooling is summarized. The review of available published literature has indicated that lack of quantitative information exists relative to collector corrosion at the present time, particularly for the higher temperature applications of solar heating and cooling compared to domestic water heating. Solar collector systems are reviewed from the corrosion/service life viewpoint, with emphasis on various applications, collector design, heat transfer fluids, and freeze protection methods. Available information (mostly qualitative) on collector corrosion technology is reviewed to indicate potential corrosion problem areas and corrosion prevention practices. Sources of limited quantitative data that are reviewed are current solar applications, research programs on collector corrosion, and pertinent experience in related applications of automotive cooling and non-solar heating and cooling. A data bank was developed to catalog corrosion information. Appendix A of this report is a bibliography of the data bank, with abstracts reproduced from presently available literature accessions (about 220). This report is presented as a descriptive summary of information that is contained in the data bank.

  16. Development of high-temperature corrosion-resistant alloys and heat-treatment regimes for components placed in the hot section of stationary gas turbines

    Science.gov (United States)

    Zvezdin, Yu. I.; Kotov, Yu. V.; Kats, E. L.; Lubenets, V. P.; Spiridonov, E. V.; Konter, M. L.

    1991-06-01

    New single-crystal alloys for the blades of gas turbines, highly corrosion-resistant alloys for guide vanes and combustion chambers, and low-cost alloys for the gears of turbine compressors have been developed and implemented. In term sof the set of properties, the new alloys are superior to foreign alloys for stationary turbines. A computer-aided design system for alloys with a given level of properties has been created for the development of a new generation of high-temperature nickel alloys. Special heat-treatment regimes, which make it possible to combine heat treatment with the production cycle involving the application of plasmas protective coatings and to achieve the combination of basic mechanical properties that is optimal for a specific component have been developed as applies to specific operating conditions of turbine components.

  17. High-temperature Corrosion of T22 Steel in N2/H2S-mixed Gas

    Directory of Open Access Journals (Sweden)

    MinJung Kim

    2017-05-01

    Full Text Available ASTM T22 steel (Fe-2.25Cr-1Mo in wt.% was corroded at 600 and 700 oC for 5-70 h under an atmospheric pressure that consisted of N2-(0.5. 2.5%H2S-mixed gas. T22 steel corroded rapidly, forming outer FeS scales and inner (FeS, FeCr2O4-mixed scale. The formation of the outer FeS scale facilitated the oxidation of Cr to FeCr2O4 in the inner scales. Since the nonprotective FeS scale was present over the whole scale, T22 steel displayed poor corrosion resistance.

  18. Boron Carbide: Stabilization of Highly-Loaded Aqueous Suspensions, Pressureless Sintering, and Room Temperature Injection Molding

    Science.gov (United States)

    Diaz-Cano, Andres

    Boron carbide (B4C) is the third hardest material after diamond and cubic boron nitride. It's unique combination of properties makes B4C a highly valuable material. With hardness values around 35 MPa, a high melting point, 2450°C, density of 2.52 g/cm3, and high chemical inertness, boron carbide is used in severe wear components, like cutting tools and sandblasting nozzles, nuclear reactors' control rots, and finally and most common application, armor. Production of complex-shaped ceramic component is complex and represents many challenges. Present research presents a new and novel approach to produce complex-shaped B4C components. Proposed approach allows forming to be done at room temperatures and under very low forming pressures. Additives and binder concentrations are kept as low as possible, around 5Vol%, while ceramics loadings are maximized above 50Vol%. Given that proposed approach uses water as the main solvent, pieces drying is simple and environmentally safe. Optimized formulation allows rheological properties to be tailored and adjust to multiple processing approaches, including, injection molding, casting, and additive manufacturing. Boron carbide samples then were pressureless sintered. Due to the high covalent character of boron carbide, multiples sintering aids and techniques have been proposed in order to achieve high levels of densification. However, is not possible to define a clear sintering methodology based on literature. Thus, present research developed a comprehensive study on the effect of multiple sintering aids on the densification of boron carbide when pressureless sintered. Relative densities above 90% were achieved with values above 30MPa in hardness. Current research allows extending the uses and application of boron carbide, and other ceramic systems, by providing a new approach to produce complex-shaped components with competitive properties.

  19. Inverted Organic Solar Cells with Low-Temperature Al-Doped-ZnO Electron Transport Layer Processed from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Qianni Zhang

    2018-01-01

    Full Text Available The aqueous-based Zn-ammine complex solutions represent one of the most promising routes to obtain the ZnO electron transport layer (ETL at a low temperature in inverted organic solar cells (OSCs. However, to dope the ZnO film processed from the Zn-ammine complex solutions is difficult since the introduction of metal ions into the Zn-ammine complex is a nontrivial process as ammonium hydroxide tends to precipitate metal salts due to acid-base neutralization reactions. In this paper, we investigate the inverted OSCs with Al-doped-ZnO ETL made by immersion of metallic Al into the Zn-ammine precursor solution. The effects of ZnO layer with different immersion time of Al on film properties and solar cell performance have been studied. The results show that, with the Al-doped-ZnO ETL, an improvement of the device performance could be obtained compared with the device with the un-doped ZnO ETL. The improved device performance is attributed to the enhancement of charge carrier mobility leading to a decreased charge carrier recombination and improved charge collection efficiency. The fabricated thin film transistors with the same ZnO or AZO films confirm the improved electrical characteristics of the Al doped ZnO film.

  20. Highly hydrogenated graphene via active hydrogen reduction of graphene oxide in the aqueous phase at room temperature.

    Science.gov (United States)

    Sofer, Zdeněk; Jankovský, Ondřej; Šimek, Petr; Soferová, Lýdie; Sedmidubský, David; Pumera, Martin

    2014-02-21

    Hydrogenated graphene and graphane are in the forefront of graphene research. Hydrogenated graphene is expected to exhibit ferromagnetism, tunable band gap, fluorescence, and high thermal and low electrical conductivity. Currently available techniques for fabrication of highly hydrogenated graphene use either a liquid ammonia (-33 °C) reduction pathway using alkali metals or plasma low pressure or ultra high pressure hydrogenation. These methods are either technically challenging or pose inherent risks. Here we wish to demonstrate that highly hydrogenated graphene can be prepared at room temperature in the aqueous phase by reduction of graphene oxide by nascent hydrogen generated by dissolution of metal in acid. Nascent hydrogen is known to be a strong reducing agent. We studied the influence of metal involved in nascent hydrogen generation and characterized the samples in detail. The resulting reduced graphenes and hydrogenated graphenes were characterized in detail. The resulting hydrogenated graphene had the chemical formula C1.16H1O0.66. Such simple hydrogenation of graphene is of high importance for large scale safe synthesis of hydrogenated graphene.

  1. Structural Evolution of Molybdenum Carbides in Hot Aqueous Environments and Impact on Low-Temperature Hydroprocessing of Acetic Acid

    Directory of Open Access Journals (Sweden)

    Jae-Soon Choi

    2015-03-01

    Full Text Available We investigated the structural evolution of molybdenum carbides subjected to hot aqueous environments and their catalytic performance in low-temperature hydroprocessing of acetic acid. While bulk structures of Mo carbides were maintained after aging in hot liquid water, a portion of carbidic Mo sites were converted to oxidic sites. Water aging also induced changes to the non-carbidic carbon deposited during carbide synthesis and increased surface roughness, which in turn affected carbide pore volume and surface area. The extent of these structural changes was sensitive to the initial carbide structure and was lower under actual hydroprocessing conditions indicating the possibility of further improving the hydrothermal stability of Mo carbides by optimizing catalyst structure and operating conditions. Mo carbides were active in acetic acid conversion in the presence of liquid water, their activity being comparable to that of Ru/C. The results suggest that effective and inexpensive bio-oil hydroprocessing catalysts could be designed based on Mo carbides, although a more detailed understanding of the structure-performance relationships is needed, especially in upgrading of more complex reaction mixtures or real bio-oils.

  2. Gas liquid equilibrium prediction of system (CO2-aqueous ethanol at moderate pressure and different temperatures using PR-EOS

    Directory of Open Access Journals (Sweden)

    Hadi Jasim Arkan

    2013-01-01

    Full Text Available One of the most important design considerations which should not be ignored during the equipment designing for some industrial purpose is vapour-liquid equilibrium (VLE. Thus, in chemical engineering, the first step is the computation of VLE properties of materials by employing Equation of state (EOS. In this study, we have used a thermodynamic model which was established for binary system of carbon dioxide (1-(2 solubility of CO2 in aqueous ethanol and it was employed to estimate the gas-liquid equilibrium at moderate pressures (till 6 bar and varying temperatures (288 K to 323 K. Peng-Robinson EOS was employed to determine the VLE properties. Mixing rules such as vanderWaals and quadratic mixing rules were also used for the determination of ethanol-water mixture critical parameters which entails the pseudo-critical method as one component and results obtained from this study were similar to the ones reported in recent literature for empirical phase equilibrium studies.

  3. Corrosion-Resistant High-Entropy Alloys: A Review

    Directory of Open Access Journals (Sweden)

    Yunzhu Shi

    2017-02-01

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

  4. Calcium and strontium isotope fractionation in aqueous solutions as a function of temperature and reaction rate; I. Calcite

    Science.gov (United States)

    AlKhatib, Mahmoud; Eisenhauer, Anton

    2017-07-01

    In order to study Strontium (Sr) partitioning and isotope fractionation of Sr and Calcium (Ca) in calcite we performed precipitation (T) experiments decoupling temperature and precipitation rate (R∗). Calcite was precipitated at 12.5, 25.0 and 37.5 °C by diffusing NH3 and CO2 gases into aqueous solutions closely following the experimental setup of Lemarchand et al. (2004). The precipitation rate (R∗) for every sample was determined applying the initial rate method and from the specific surface area of almost all samples for each reaction. The order of reaction with respect to Ca2+ ions was determined to be one and independent of T. However, the order of reaction with respect to HCO3- changed from three to one as temperature increases from 12.5, 25 °C and 37.5 °C. Strontium incorporated into calcite (expressed as DSr = [Sr/Ca]calcite/[Sr/Ca]solution) was found to be R∗ and T dependent. As a function of increasing R∗ the Δ88/86Sr-values become more negative and as temperature increases the Δ88/86Sr values also increase at constant R∗. The DSr and Δ88/86Sr-values are correlated to a high degree and depend only on R∗ being independent of temperature, complexation and varying initial ratios. Latter observation may have important implications for the study of diagenesis, the paleo-sciences and the reconstruction of past environmental conditions. Calcium isotope fractionation (Δ44/40Ca) was also found to be R∗ and T dependent. For 12.5 and 25.0 °C we observe a general increase of the Δ44/40Ca values as a function of R∗ (Lemarchand et al. type behavior, Lemarchand et al. (2004)). Whereas at 37.5 °C a significant decreasing Δ44/40Ca is observed relative to increasing R∗ (Tang et al. type behavior, Tang et al. (2008)). In order to reconcile the discrepant observations we suggest that the temperature triggered change from a Ca2+-NH3-aquacomplex covalent controlled bonding to a Ca2+-H2O-aquacomplex van-der-Waals controlled bonding caused the change

  5. Application of in-service temperature lowering to reduce radioactivity corrosion product deposition on carbon steel piping of BWR residual heat removal system

    Energy Technology Data Exchange (ETDEWEB)

    Aizawa, Motohiro; Chiba, Yoshinori [Hitachi Engineering Co., Ltd., Nuclear Power Plant Engineering Dept., Hitachi, Ibaraki (Japan); Ohsumi, Katsumi [Hitachi Ltd., Power and Industrial Systems Nuclear Systems Division, Hitachi, Ibaraki (Japan); Uchida, Shunsuke [Tohoku Univ., Graduate School of Engineering, Dept. of Quantum Science and Energy Engineering, Sendai, Miyagi (Japan); Takahashi, Toshihiko; Saitoh, Takeshi [Hokuriku Electric Power Company, Shika Nuclear Power Station, Radiation Safety and Chemistry Section, Shika, Ishikawa (Japan)

    2002-10-01

    Assessment of plant data and experiments on deposition of ion species on carbon steel were carried out in order to develop suitable countermeasures to reduce RHR (residual heat removal) piping dose rate. It was thought that radioactivity deposits on the RHR piping were mainly from radioactive ion species in the coolant and they were enhanced by the dehydration reaction of corrosion products on the piping. From an evaluation for temperature dependence of the dehydration reaction, it was proposed to lower the start-up temperature of RHR operation as a way to reduce radioactivity deposition. Feasibility studies of improved RHR operation were conducted and test operations were carried out in the Shika Nuclear Power Station Unit 1. Application of the improved RHR operation resulted in a temperature reduction from 150degC to 110degC, and a radioactivity deposition reduction on the RHR piping to one-fifth of that in conventional RHR operation. The improved RHR operation has now been applied to more than fifteen Japanese BWRs and significant suppression effects of radioactivity deposition have been observed. (author)

  6. Method of inhibiting corrosion in acidizing wells

    Energy Technology Data Exchange (ETDEWEB)

    Williams, D.A.; Holifield, P.K.; Looney, J.R.; McDougall, L.A.

    1992-02-18

    This patent describes improvement in a method of acidizing a subterranean formation penetrated by a borehole which has metal pipe positioned therein wherein an aqueous acid solution is pumped down the pipe and into the formation. The improvement comprises introducing components of a nonacetylenic corrosion inhibitor directly into the aqueous acid solution to form the corrosion inhibitor in the acid solution at a concentration to inhibit corrosion of the metal, the components consisting essentially of: an antimony compound which provides from 0.04 to 2.0 wt % of antimony ions in the aqueous acid; from 0.2 to 10 wt % of a quaternary ammonium compound capable of forming a complex with the antimony ions; and from 0.1 to 25 wt % of a surfactant capable of water wetting the pipe.

  7. Corrosion Cost and Corrosion Map of Korea - Based on the Data from 2005 to 2010

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y. S.; Lim, H. K. [Andong National University, Andong (Korea, Republic of); Kim, J. J. [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Hwang, W. S. [Inha University, Incheon (Korea, Republic of); Park, Y. S. [Yonsei University, Seoul (Korea, Republic of)

    2011-04-15

    Corrosion of metallic materials occurs by the reaction with corrosive environment such as atmosphere, marine, soil, urban, high temperature etc. In general, reduction of thickness and cracking and degradation are resulted from corrosion. Corrosion in all industrial facilities and infrastructure causes large economic losses as well as a large number of accidents. Economic loss by corrosion has been reported to be nearly 1-6% of GNP or GDP. In order to reduce corrosion damage of industrial facilities, corrosion map as well as a systematic investigation of the loss of corrosion in each industrial sector is needed. The Corrosion Science Society of Korea in collaboration with 15 universities and institutes has started to survey on the cost of corrosion and corrosion map of Korea since 2005. This work presents the results of the survey on cost of corrosion by Uhlig, Hoar, and input-output methods, and the evaluation of atmospheric corrosion rate of carbon steel, weathering steel, galvanized steel, copper, and aluminum in Korea. The total corrosion cost was estimated in terms of the percentage of the GDP of industry sectors and the total GDP of Korea. According to the result of Input/output method, corrosion cost of Korea was calculated as 2.9% to GDP (2005). Time of wetness was shown to be categories 3 to 4 in all exposure areas. A definite seasonal difference was observed in Korea. In summer and fall, time of wetness was higher than in other seasons. Because of short exposure period (12 months), significant corrosion trends depending upon materials and exposure corrosion environments were not revealed even though increased mass loss and decreased corrosion rate by exposure time.

  8. Coolant Compatibility Studies for Fusion and Fusion-Fission Hybrid Reactor Concepts: Corrosion of Oxide Dispersion Strengthened Iron-Chromium Steels and Tantalum in High Temperature Molten Fluoride Salts

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, Joseph [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); El-dasher, Bassem [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ferreira, James [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Caro, Magdalena Serrano de [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kimura, Akihiko [Kyoto Univ. (Japan). Inst. of Advanced Energy

    2010-05-04

    Alloys such as 12YWT & 14YWT have exceptional high-temperature strength at temperatures greater than 550 C. This class of materials has also demonstrated relatively little radiation induced swelling at damage levels of at least 75 dpa in sodium-cooled fast reactors. However, corrosion of oxide dispersion strengthened (ODS) steels in high temperature molten fluoride salts may limit the life of advanced reactor systems, including some fusion and fusionfission hybrid systems that are now under consideration. This paper reports corrosion studies of ODS steel in molten fluoride salts at temperatures ranging from 600 to 900 C. Electrochemical impedance spectroscopy (EIS) was used to measure the temperature dependence of charge transfer kinetics in situ, while an environmental electron microscope (ESEM) equipped with energy dispersive spectroscopy (EDS) was used for postexposure examination of test samples. ODS steel experienced corrosion in the molten fluoride salts at 550 to 900 C, even in carefully controlled glove-box environments with very low levels of oxygen and moisture. The observed rate of attack was found to accelerate dramatically at temperatures above 800 C. Tantalum and tantalum-based alloys such as Ta-1W and Ta-10W have exceptional high temperature strength, far better than ODS steels. Unlike ODS steels, tantalum has been found to exhibit some immunity to corrosive attack by molten fluoride salts at temperatures as high as 900 C, though there is some indication that grain boundary attack may have occurred. Unfortunately, tantalum alloys are known to become brittle during irradiation and exposure to hydrogen, both of which are important in fusion applications.

  9. Cracking and corrosion recovery boiler

    Energy Technology Data Exchange (ETDEWEB)

    Suik, H. [Tallinn Technical University, Horizon Pulp and Paper, Tallinn (Estonia)

    1998-12-31

    The corrosion of heat surfaces and the cracking the drums are the main problems of the recovery boiler. These phenomena have been appeared during long-term operation of boiler `Mitsubishi - 315` erected at 1964. Depth of the crack is depending on the number of shutdowns and on operation time. Corrosion intensity of different heat surfaces is varying depend on the metal temperature and the conditions at place of positioning of tube. The lowest intensity of corrosion is on the bank tubes and the greatest is on the tubes of the second stage superheater and on the tubes at the openings of air ports. (orig.) 5 refs.

  10. High-temperature corrosion behavior of coatings and ODS alloys based on Fe{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.; Pint, B.A.; Wright, I.G. [Oak Ridge National Lab., TN (United States)

    1996-08-01

    Iron-aluminide coatings were prepared by gas tungsten arc and gas metal arc weld-overlay techniques. All the weld overlays showed good oxidation/sulfidation behavior under isothermal conditions, including a gas metal arc deposit with only 21 at.% Al. A rapid degradation in corrosion resistance was observed under thermal cycling conditions when the initially grown scales spalled and the subsequent rate of reaction was not controlled by the formation of slowly growing aluminum oxides. Higher starting aluminum concentrations (>{approximately}25 at.%) are needed to assure adequate oxidation/sulfidation lifetimes of the weld overlays. A variety of stable oxides was added to a base Fe-28 at.% Al-2 % Cr alloy to assess the effect of these dopants on the oxidation behavior at 1200{degrees}C. A Y{sub 2}O{sub 3} dispersion improved the scale adhesion relative to a Zr alloy addition, but wasn`t as effective as it is in other alumina-forming alloys. Preliminary data for powder-processed Fe-28 at.% Al-2% Cr exposed to the H{sub 2}S-H{sub 2}-H{sub 2}O-Ar gas at 800{degrees}C showed that the oxidation/sulfidation rate was similar to that of many Fe{sub 3}Al alloys produced by ingot metallurgy routes.

  11. Equilibrium solubility of CO{sub 2} in aqueous solutions of 1-amino-2-propanol as function of concentration, temperature, and pressure

    Energy Technology Data Exchange (ETDEWEB)

    Rebolledo-Morales, Miguel Angel; Rebolledo-Libreros, Maria Esther [Instituto Mexicano del Petroleo, Direccion de Investigacion y Posgrado, Programa de Ingenieria Molecular, Area de Investigacion de Termofisica, Eje Central Lazaro Cardenas Norte 152, 07730 Mexico, D.F. (Mexico); Trejo, Arturo, E-mail: atrejo@imp.m [Instituto Mexicano del Petroleo, Direccion de Investigacion y Posgrado, Programa de Ingenieria Molecular, Area de Investigacion de Termofisica, Eje Central Lazaro Cardenas Norte 152, 07730 Mexico, D.F. (Mexico)

    2011-05-15

    Research highlights: Gas solubility of CO{sub 2} in aqueous solutions of 1-amino-2-propanol was measured. Solubility increases as pressure and concentration of 1-amino-2-propanol increase. The Kent-Eisenberg model was used to correlate all the experimental results. Aqueous solutions of MIPA are an excellent alternative to use in gas purification. - Abstract: Using a dynamic method with recirculation of the vapour phase, experimental values for the gas solubility of carbon dioxide in aqueous solutions of 1-amino-2-propanol (MIPA) were measured at T = (313.15 and 393.15) K, over the pressure range of (0.2 to 2436.4) kPa. The concentrations of the studied aqueous MIPA solutions were (0.20, 0.30, 0.40, and 0.50) mass fraction. The results of gas solubility are given as the partial pressure of CO{sub 2}, p{sub CO{sub 2}}, against its mole ratio, {alpha}{sub CO{sub 2}} (mol CO{sub 2} {center_dot} mol{sup -1} MIPA), and its mole fraction, x{sub CO{sub 2}}. It is observed that the solubility of CO{sub 2} increases as the concentration of MIPA in solution increases, at a given temperature throughout the pressure range considered; also the solubility values increase, under constant temperature, as the pressure increases in the studied concentration range of MIPA. The physicochemical model of Kent and Eisenberg was used to correlate simultaneously all the experimental results of the solubility of CO{sub 2} in the studied aqueous solutions of MIPA. The model correlates satisfactorily the experimental results. The deviation for pressure was 96.9 kPa using 62 experimental solubility points. The solubility results of carbon dioxide presented in this work are compared with those reported in the literature for aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), diisopropanolamine (DIPA), and N-methyldiethanolamine (MDEA) and it is possible to conclude that the aqueous solutions of MIPA are an excellent alternative to use in gas purification processes, since the

  12. Survey of materials and corrosion performance in dry cooling applications

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, A.B.; Pratt, D.R.; Zima, G.E.

    1976-03-01

    The report presented summarizes aqueous and air-side corrosion aspects of candidate materials in dry cooling applications. The applications include piping, condensers, louvers, structures, and the air-cooled surfaces.

  13. Morphology of stress corrosion cracking due to exposure to high-temperature water containing hydrogen peroxide in stainless steel specimens with different crevice lengths

    Science.gov (United States)

    Nakano, Junichi; Sato, Tomonori; Kato, Chiaki; Yamamoto, Masahiro; Tsukada, Takashi; Kaji, Yoshiyuki

    2013-10-01

    Crack growth tests were performed in high-temperature water containing hydrogen peroxide (H2O2) to evaluate the relationships between the crevice structure and H2O2 on stress corrosion cracking (SCC) growth morphology of stainless steel (SS). Small compact tension (CT) specimens were prepared from thermally sensitized type 304 SS. 20-300 ppb H2O2 was injected into the high-temperature water at 561 K. Intergranular SCC (IGSCC) and transgranular SCC were observed near the side grooves and the central region of the original CT specimens, respectively. Chevron notches were removed from the CT specimens after fatigue pre-crack introduction. Owing to pre-crack shortening, the IGSCC area expanded to the central region of the CT specimens and increased with H2O2 concentration. The effects of H2O2 on SCC appeared intensely near the surfaces exposed to high levels of H2O2. Microanalysis and distribution examination of oxide layers were performed and the percentage of H2O2 remaining in the crack was calculated.

  14. Determination of Water Vapor Pressure Over Corrosive Chemicals Versus Temperature Using Raman Spectroscopy as Exemplified with 85.5% Phosphoric Acid

    DEFF Research Database (Denmark)

    Rodier, Marion; Li, Qingfeng; Berg, Rolf W.

    2016-01-01

    A method to determine the water vapor pressure over a corrosive substance was developed and tested with 85.5 ± 0.4% phosphoric acid. The water vapor pressure was obtained at a range of temperatures from ∼25 ℃ to ∼200 ℃ using Raman spectrometry. The acid was placed in an ampoule and sealed...... with a reference gas (either hydrogen or methane) at a known pressure (typically ∼0.5 bar). By comparing the Raman signals from the water vapor and the references, the water pressure was determined as a function of temperature. A considerable amount of data on the vapor pressure of phosphoric acid are available...... in the literature, to which our results could successfully be compared. A record value of the vapor pressure, 3.40 bar, was determined at 210 ℃. The method required a determination of the precise Raman scattering ratios between the substance, water, and the used reference gas, hydrogen or methane. In our case...

  15. Mathematical model for galvanic corrosion of steel–copper couple in petroleum waste water in presence of friendly corrosion inhibitor

    National Research Council Canada - National Science Library

    Khadom, Anees A; Abod, Baker M

    2017-01-01

    Galvanic corrosion of steel–copper couple in saline petroleum wastewater in the absence and presence of curcuma extract as corrosion inhibitor was studied as a function of temperature, velocity, and inhibitor concentration...

  16. Shield effect of polyaniline between zinc active material and aqueous electrolyte in zinc-air batteries

    Science.gov (United States)

    Jo, Yong Nam; Kang, Suk Hyun; Prasanna, K.; Eom, Seung Wook; Lee, Chang Woo

    2017-11-01

    The self-discharge behavior of zinc-air batteries is a critical issue that is induced by corrosion and hydrogen evolution reaction (HER) of zinc anodes. Polyaniline (PANI) coatings help control the HER and the corrosion reaction. Herein, PANI is synthesized with different amounts of HCl (20, 50, 100 ml). Among these, the PANI synthesized using 20 ml of HCl (20PANI@Zn) is the most effective for reducing the self-discharge behavior because it provides more amount of coating layer on the surfaces of the zinc particles compared to other prepared materials. This layer prevents direct contact between zinc and the aqueous electrolyte and minimize HER. The 20PANI@Zn shows 85% corrosion inhibition efficiency against pure zinc and results in 97.81% capacity retention after 24 h storage against no-storage condition at ambient temperature.

  17. DWPF corrosion study

    Energy Technology Data Exchange (ETDEWEB)

    Selby, C.L.

    1986-12-17

    Corrosion of candidate alloys for the DWPF SRAT, SME, and melter was tested in the large (1/3 scale) SRAT/SME, the 200th scale SRAT/SME, and the LSFM. Flat or twisted coupons with or without a weld bead and U-bend specimens (specimens bent into a ''U'' shape and bolted together at the ends to stress the bend area) were installed on racks that ensured electrical isolation to avoid galvanic effects. Teflon/reg sign/ washers isolated the low temperature exposure racks and ceramic washers isolated the high temperature exposure racks. Serrated washers simulated crevices, but crevice corrosion did not result. 9 refs., 9 tabs.

  18. Corrosion rate sensors for soil, water and concrete

    Energy Technology Data Exchange (ETDEWEB)

    Ansuini, F. [Electrochemical Devices, Inc., Albion, RI (United States); Yaffe, M. [Gamry Instruments, Inc., Willow Grove, PA (United States); Chaker, V. [Port Authority of New York and New Jersey, New York, NY (United States)

    1995-10-01

    Present concern over the condition of the infrastructure has created a need to monitor corrosion of large field structures in real time. New sensors have been developed for measuring corrosion rates of steel in concrete, underground and aqueous environments. This paper will discuss sensor designs including both the transducer and the electronics as well as field experience with these sensors in concrete.

  19. 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.

  20. ANALYSIS OF PITTING CORROSION ON AN INCONEL 718 ALLOY SUBMITTED TO AGING HEAT TREATMENT

    Directory of Open Access Journals (Sweden)

    Felipe Rocha Caliari

    2014-10-01

    Full Text Available Inconel 718 is one of the most important superalloys, and it is mainly used in the aerospace field on account of its high mechanical strength, good resistance to fatigue and creep, good corrosion resistance and ability to operate continuously at elevated temperatures. In this work the resistance to pitting corrosion of a superalloy, Inconel 718, is analyzed before and after double aging heat treatment. The used heat treatment increases the creep resistance of the alloy, which usually is used up to 0.6 Tm. Samples were subjected to pitting corrosion tests in chloride-containing aqueous solution, according to ASTM-F746-04 and the procedure described by Yashiro et al. The results of these trials show that after heat treatment the superalloy presents higher corrosion resistance, i.e., the pitting corrosion currents of the as received surfaces are about 6 (six times bigger (~0.15 mA than those of double aged surfaces (~0.025 mA.

  1. Influence of delta ferrite on corrosion susceptibility of AISI 304 austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Lawrence O. Osoba

    2016-12-01

    Full Text Available In the current study, the influence of delta (δ ferrite on the corrosion susceptibility of AISI 304 austenitic stainless steel was evaluated in 1Molar concentration of sulphuric acid (H2SO4 and 1Molar concentration of sodium chloride (NaCl. The study was performed at ambient temperature using electrochemical technique—Tafel plots to evaluate the corrosive tendencies of the austenitic stainless steel sample. The as-received (stainless steel specimen and 60% cold-worked (stainless steel specimens were isothermally annealed at 1,100°C for 2 h and 1 h, respectively, and quenched in water. The results obtained show that the heat-treated specimen and the 60% cold-worked plus heat-treated specimen exhibited higher corrosion susceptibility than the as-received specimen, which invariably contained the highest fraction of δ ferrite particles. The finding shows that the presence of δ ferrite, in which chromium (Cr, the main corrosion inhibitor segregates, does not degrade and or reduces the resistance to aqueous corrosion of the austenitic stainless steel material.

  2. Experimental study for determining the corrosion in situ of SS-304 in heat transformers applying electrochemical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Cuevas-Arteaga, C.; Siqueiros, J.; Romero, R.J. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas - UAEM, Cuernavaca, Morelos (Mexico)

    2009-07-01

    In this work the corrosion performance of SS-304 experimentally tested in a single stage absorption heat transformer (SSAHT) operating with lithium-bromide aqueous solution and water as the absorbent and work fluids coupled to a desalinizer is reported. The main aim of this work was to determine the corrosion rate and corrosion mechanism of SS-304 through some electrochemical cells designed for this specific purpose and connected in one of the pipe constituting the heat transformer. Some electrochemical techniques named electrochemical noise (EN), and electrochemical impedance spectroscopy (EIS) were applied under the next experimental conditions: temperature 83-85 C, concentration of LiBr-H{sub 2}O corrosive solution 56 (wt.%), and flow rate 0.0278 m{sup 3}/s. According to the physical characterization, SS-304 suffered a mixed corrosion process, which is in concordance with the signal noise pattern obtained. Through the Nyquist plots from EIS the corrosion process was obtained as controlled by charge transfer at the first 3:25 h, and then a diffusion effect was observed. (authors)

  3. Responsive polymers-based dual fluorescent chemosensors for Zn2+ ions and temperatures working in purely aqueous media.

    Science.gov (United States)

    Liu, Tao; Liu, Shiyong

    2011-04-01

    We report on the fabrication of responsive double hydrophilic block copolymers (DHBCs)-based dual fluorescent chemosensors for Zn(2+) ions and temperatures and investigate the effects of thermo-induced micellization and detection conditions on the probing sensitivity and binding reversibility of Zn(2+) ions. A novel quinoline-based polarity-sensitive and Zn(2+)-recognizing fluorescent monomer (ZQMA, 6) was synthesized at first. Well-defined DHBCs bearing quinoline-based Zn(2+)-recognizing moieties (ZQMA) in the thermoresponsive block, PEG-b-P(MEO(2)MA-co-OEGMA-co-ZQMA), were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization of 2-(2-methoxyethoxy)ethyl methacrylate (MEO(2)MA), oligo(ethylene glycol) monomethyl ether methacrylate (OEGMA), and ZQMA in the presence of PEG-based macroRAFT agent. The OEGMA contents in the thermoresponsive block varied in the range of 0-12.0 mol % to tune their lower critical solution temperatures (LCSTs). At 20 °C, almost nonfluorescent PEG-b-P(MEO(2)MA-co-ZQMA) molecularly dissolved in water and can selectively bind with Zn(2+) ions over other common metal ions, leading to prominent fluorescence enhancement due to the coordination of ZQMA with Zn(2+). At a polymer concentration of 0.2 g/L, the Zn(2+) detection limit can be down to ~3.0 nM. PEG-b-P(MEO(2)MA-co-ZQMA) self-assembles into micelles possessing P(MEO(2)MA-co-ZQMA) cores and well-solvated PEG coronas upon heating to above the LCST, and the fluorescence intensity exhibit ~6.0-fold increase due to the fact that ZQMA moieties are now located in a more hydrophobic microenvironment. Compared to the unimer state at 20 °C, although PEG-b-P(MEO(2)MA-co-ZQMA) micelles possess a slightly decreased detection limit for Zn(2+) (~14 nM), reversible binding between ZQMA moieties and Zn(2+) ions at 37 °C can be achieved, as evidenced by the on/off switching of fluorescence emission via the sequential addition of Zn(2+) and EDTA. In vitro fluorescence

  4. Release of cerium dibutylphosphate corrosion inhibitors from highly filled epoxy coating systems

    NARCIS (Netherlands)

    Soestbergen, M. van; Baukh, V.; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2014-01-01

    Carcinogenic chromates are phased out as corrosion inhibitors in organic coatings, and are replaced by benign alternatives. Cerium-based compounds are excellent corrosion inhibitors in an aqueous environment. However, whether they are effective as corrosion inhibitor in an organic coating also

  5. Corrosion behavior of duplex coatings

    Directory of Open Access Journals (Sweden)

    K. Raghu Ram Mohan Reddy

    2016-07-01

    Full Text Available The titanium alloys are used in defense, aerospace, automobile, chemical plants and biomedical applications due to their very high strength and lightweight properties. However, corrosion is a life-limiting factor when Ti alloys are exposed to different chemical environments at high temperatures. In the present paper, duplex NiCrAlY/WC–Co coating is coated onto Ti6Al4V substrate to investigate the corrosion behavior of both coated samples and the substrate. The duplex coating was performed with NiCrAlY as the intermediate coat of 200 μm thickness deposited by HVOF process and WC–Co ceramic top coat with varying thicknesses of 250 μm, 350 μm and 450 μm deposited by DS process. Potentiodynamic polarization tests were employed to investigate the corrosion performance of duplex coated samples and substrate in Ringer’s solution at 37 °C and pH value was set to 5.7. Finally the results reveal that 350 μm thick coated samples showed highest corrosion resistance compared to 250 μm thick samples as well as bare substrate. However, the 450 μm thick coated sample showed poor corrosion resistance compared to the substrate. The scale formed on the samples upon corrosion was characterized by using SEM analysis to understand the degree of corrosion behavior.

  6. Underground pipeline corrosion

    CERN Document Server

    Orazem, Mark

    2014-01-01

    Underground pipelines transporting liquid petroleum products and natural gas are critical components of civil infrastructure, making corrosion prevention an essential part of asset-protection strategy. Underground Pipeline Corrosion provides a basic understanding of the problems associated with corrosion detection and mitigation, and of the state of the art in corrosion prevention. The topics covered in part one include: basic principles for corrosion in underground pipelines, AC-induced corrosion of underground pipelines, significance of corrosion in onshore oil and gas pipelines, n

  7. Corrosion Properties of Laser Welded Stainless Steel

    DEFF Research Database (Denmark)

    Weldingh, Jakob; Olsen, Flemmming Ove

    1997-01-01

    In this paper the corrosion properties of laser welded AISI 316L stainless steel are examined. A number of different welds has been performed to test the influence of the weld parameters of the resulting corrosion properties. It has been chosen to use the potential independent critical pitting...... temperature (CPT) test as corrosion test. The following welding parameters are varied: Welding speed, lsser power, focus point position and laser operation mode (CW or pulsed)....

  8. Influence of pH, temperature, and concentration on stabilization of aqueous hornet silk solution and fabrication of salt-free materials.

    Science.gov (United States)

    Kameda, Tsunenori

    2015-01-01

    We found that an aqueous solution of silk from cocoons produced by hornet larvae (hornet silk) can be obtained when the solution is adjusted to basic conditions of pH > 9.2. It is known that native hornet cocoons can be dissolved in concentrated aqueous solution of salts, such as lithium bromide (LiBr) and calcium chloride (CaCl2). Upon the removal of these salts from solution by dialysis, solidification, gelation, or sedimentation of hornet silk is known to occur. In the present study, under basic conditions, however, no such solidification occurred, even after salt removal. In this study, ammonia was used for alkalization of solution because it is volatilized during the casting process and pure hornet silk materials can be obtained after drying. The effects of the concentrations of hornet silk and ammonia, as well as dialysis temperature, on preventing gelation during dialysis were investigated. Dialysis conditions that limit the degradation of hornet silk by hydrolysis in alkali solution were identified. Moreover, casting conditions to prepare flexible and transparent hornet silk film from aqueous ammonia solution were optimized. Molecular structural analysis of hornet silk in aqueous ammonia solution and cast film indicated the formation of α-helix conformations. © 2014 Wiley Periodicals, Inc.

  9. Effect of flue gas composition on deposit induced high temperature corrosion under laboratory conditions mimicking biomass firing. Part I: Exposures in oxidizing and chlorinating atmospheres

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Kiamehr, Saeed; Montgomery, Melanie

    2017-01-01

    In biomass fired power plants, deposition of alkali chlorides on superheaters, aswell as the presence of corrosive flue gas species, give rise to fast corrosion ofsuperheaters. In order to understand the corrosion mechanism under thiscomplex condition, the influence of the flue gas composition...... on hightemperature corrosion of an austenitic superheater material under laboratoryconditions mimicking biomass firing is investigated in this work. Exposuresinvolving deposit (KCl)-coated and deposit-free austenitic stainless steel (TP347H FG) samples were conducted isothermally at 560 8C for 72 h, under...... only in an oxidizing-chlorinating atmosphere, otherwise corrosionresults in formation of a duplex oxide. Corrosion attack on deposit-coatedsamples was higher than on deposit-free samples irrespective of the gaseousatmosphere. Specifically, severe volatilization of alloying elements occurred ondeposit...

  10. Corrosion resistance of cast irons and titanium alloys as reference engineered metal barriers for use in basalt geologic storage: a literature assessment

    Energy Technology Data Exchange (ETDEWEB)

    Charlot, L.A.; Westerman, R.E.

    1981-07-01

    A survey and assessment of the literature on the corrosion resistance of cast irons and low-alloy titanium are presented. Selected engineering properties of cast iron and titanium are briefly described; however, the corrosion resistance of cast iron and titanium in aqueous solutions or in soils and their use in a basalt repository are emphasized. In evaluating the potential use of cast iron and titanium as structural barrier materials for long-lived nuclear waste packages, it is assumed that titanium has the general corrosion resistance to be used in relatively thin cross sections whereas the cost and availability of cast iron allows its use even in very thick cross sections. Based on this assumption, the survey showed that: The uniform corrosion of low-alloy titanium in a basalt environment is expected to be extremely low. A linear extrapolation of general corrosion rates with an added corrosion allowance suggests that a 3.2- to 6.4-mm-thick wall may have a life of 1000 yr. Pitting and crevice corrosion are not likely corrosion modes in basalt ground waters. It is also unlikely that stress corrosion cracking (SCC) will occur in the commercially pure (CP) titanium alloy or in palladiumor molybdenum-alloyed titanium materials. Low-alloy cast irons may be used as barrier metals if the environment surrounding the metal keeps the alloy in the passive range. The solubility of the corrosion product and the semipermeable nature of the oxide film allow significant uniform corrosion over long time periods. A linear extrapolation of high-temperature corrosion rates on carbon steels and corrosion rates of cast irons in soils gives an estimated metal penetration of 51 to 64 mm after 1000 yr. A corrosion allowance of 3 to 5 times that suggests that an acceptable cast iron wall may be from 178 to 305 mm thick. Although they cannot be fully assessed, pitting and crevice corrosion should not affect cast iron due to the ground-water chemistry of basalt.

  11. Al2O3 coatings against high temperature corrosion deposited by metal-organic low pressure chemical vapour deposition

    NARCIS (Netherlands)

    van Corbach, H.D.; Haanappel, V.A.C.; Haanappel, V.A.C.; Fransen, T.; Gellings, P.J.

    1994-01-01

    Metal-organic chemical vapour deposition of thin amorphous films of Al2O3 on steels was performed at low pressure. Aluminium tri-sec-butoxide (ATSB) was used as a precursor. The effects of the deposition temperature (200–380 °C), the deposition pressure (0.17–1.20 kPa) and the ATSB concentration

  12. Laser Raman Spectroscopy in studies of corrosion and electrocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Melendres, C.A.

    1988-01-01

    Laser Raman Spectroscopy (LRS) has become an important tool for the in-situ structural study of electrochemical systems and processes in recent years. Following a brief introduction of the experimental techniques involved in applying LRS to electrochemical systems, we survey the literature for examples of studies in the inhibition of electrode reactions by surface films (e.g., corrosion and passivation phenomena) as well as the acceleration of reactions by electro-sorbates (electrocatalysis). We deal mostly with both normal and resonance Raman effects on fairly thick surface films in contrast to surface-enhanced Raman investigations of monolayer adsorbates, which is covered in another lecture. Laser Raman spectroelectrochemical studies of corrosion and film formation on such metals as Pb, Ag, Fe, Ni, Co, Cr, Au, stainless steel, etc. in various solution conditions are discussed. Further extension of the technique to studies in high-temperature and high-pressure aqueous environments is demonstrated. Results of studies of the structure of corrosion inhibitors are also presented. As applications of the LRS technique in the area of electrocatalysis, we cite studies of the structure of transition metal macrocyclic compounds, i.e., phthalocyanines and porphyrins, used for catalysis of the oxygen reduction reaction. 104 refs., 20 figs.

  13. Optical Measurement Technologies for High Temperature, Radiation Exposure, and Corrosive Environments—Significant Activities and Findings: In-vessel Optical Measurements for Advanced SMRs

    Energy Technology Data Exchange (ETDEWEB)

    Anheier, Norman C.; Cannon, Bret D.; Qiao, Hong (Amy); Suter, Jonathan D.

    2012-09-01

    Development of advanced Small Modular Reactors (aSMRs) is key to providing the United States with a sustainable, economically viable, and carbon-neutral energy source. The aSMR designs have attractive economic factors that should compensate for the economies of scale that have driven development of large commercial nuclear power plants to date. For example, aSMRs can be manufactured at reduced capital costs in a factory and potentially shorter lead times and then be shipped to a site to provide power away from large grid systems. The integral, self-contained nature of aSMR designs is fundamentally different than conventional reactor designs. Future aSMR deployment will require new instrumentation and control (I&C) architectures to accommodate the integral design and withstand the extreme in-vessel environmental conditions. Operators will depend on sophisticated sensing and machine vision technologies that provide efficient human-machine interface for in-vessel telepresence, telerobotic control, and remote process operations. The future viability of aSMRs is dependent on understanding and overcoming the significant technical challenges involving in-vessel reactor sensing and monitoring under extreme temperatures, pressures, corrosive environments, and radiation fluxes

  14. Corrosion Resistance of Ni-Based WC/Co Coatings Deposited by Spray and Fuse Process Varying the Oxygen Flow

    Science.gov (United States)

    Jiménez, H.; Olaya, J. J.; Alfonso, J. E.; Mtshali, C. B.; Pineda-Vargas, C. A.

    2017-10-01

    In this work, the effect of oxygen flow variation in the corrosion behavior of Ni-based WC/Co coatings deposited by spray and fuse process was investigated. The coatings were deposited on gray cast iron substrates using a Superjet Eutalloy thermal spraying gun. The morphology of the coatings was analyzed using scanning electron microscopy. The crystallographic phases were registered by x-ray diffraction (XRD), the diffraction patterns show the crystalline phases of the powder components with principal reflections for Ni and WC, the increase in flame temperature, due to the oxygen flow variation, generated amorphization in the nickel and an important crystallization of the planes (111) and (222) of WC as well as the decarburization of WC in W2C and W metallic. The corrosion behavior was investigated at room temperature in a 3.5% w/w aqueous solution of NaCl via potentiodynamic polarization. Electrochemical corrosion test showed that the coatings deposited under neutral flame conditions with an oxygen flow of 12.88 SCFH evidenced higher corrosion resistance. The chemical composition of the coatings and corrosion areas were analyzed by particle-induced x-ray emission, this technique permitting the corroboration of the decarburization process of WC determined by XRD and the formation of Cl structures.

  15. Metal temperature monitoring in corrosive gases at high temperature and high thermal flows; Monitoreo de temperaturas de metal en gases corrosivos a alta temperatura y altos flujos termicos

    Energy Technology Data Exchange (ETDEWEB)

    Huerta Espino, Mario; Martinez Flores, Marco Antonio; Martinez Villafane, Alberto; Porcayo Calderon, Jesus; Gomez Guzman, Roberto; Reyes Cervantes, Fernando [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1990-12-31

    The direct measurement of metal temperatures during operation in superheater, reheater, and water wall tubes in zones exposed to high thermal flows is of great interest for the operation and analysis of the correct functioning of a steam generator. The operation temperature measurement of these zones differs very much of the monitored temperature in headers in the dead chamber, since the temperature measured in this zone is the steam temperature that does not reflect the one detected in the gas zone. For this reason, the thermocouples implant in gas zones will detect the real metal temperature and the incidence that some operation variables might have on it (Martinez et al., (1990). [Espanol] La medicion directa de temperaturas de metal durante operacion en tubos de sobrecalentador, recalentador y pared de agua en zonas expuestas a altos flujos termicos es de gran interes para la operacion y analisis del buen funcionamiento de un generador de vapor. La medicion de la temperatura de operacion de estas zonas, difiere mucho de la temperatura monitoreada en cabezales en zona de camara muerta, ya que la temperatura registrada en esta zona es la de vapor que no es un reflejo de la detectada en zona de gases. Por esta razon, la implantacion de termopares en zona de gases detectara la temperatura de metal real y la incidencia que algunas variables de operacion tengan sobre esta (Martinez et al., 1990).

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yan; Huang, Zhiquan; Yan, Qin; Liu, Chen; Liu, Peng; Zhang, Yi [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Guo, Changhong; Jiang, Guirong [College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004 (China); Shen, Dejiu, E-mail: DejiuShen@163.com [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2016-08-15

    Highlights: • Corrosion behaviors of a PEO coating was investigated after the salt spray test. • Corrosion products have significant effects on corrosion behaviors of the coating. • An electrochemical corrosion model is proposed. - Abstract: 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.

  17. Thermally activated low temperature creep and primary water stress corrosion cracking of NiCrFe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hall, M.M. Jr.

    1993-10-01

    A phenomenological SCC-CGR model is developed based on an apriori assumption that the SCC-CGR is controlled by low temperature creep (LTC). This mode of low temperature time dependent deformation occurs at stress levels above the athermal flow stress by a dislocation glide mechanism that is thermally activated and may be environmentally assisted. The SCC-CGR model equations developed contain thermal activation parameters descriptive of the dislocation creep mechanism. Thermal activation parameters are obtained by fitting the CGR model to SCC-CGR data obtained on Alloy 600 and Alloy X-750. These SCC-CGR activation parameters are compared to LTC activation parameters obtained from stress relaxation tests. When the high concentration of hydrogen at the tip of an SCC crack is considered, the SCC-CGR activation energies and rate sensitivities are shown to be quantitatively consistent with hydrogen reducing the activation energy and increasing the strain rate sensitivity in LTC stress relaxation tests. Stress dependence of SCC-CGR activation energy consistent with that found for the LTC activation energy. Comparisons between temperature dependence of the SCC-CGR stress sensitivity and LTC stress sensitivity provide a basis for speculation on effects of hydrogen and solute carbon on SCC crack growth rates.

  18. The effect of chloride on general corrosion and crack initiation of low-alloy steels in oxygenated high-temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Herbst, Matthias; Roth, Armin [AREVA NP GmbH, Erlangen (Germany); Widera, Martin [RWE Power AG, Essen (Germany); Kuester, Karin; Huettner, Frank [Vattenfall Europe Nuclear Energy GmbH, Hamburg (Germany); Nowak, Erika [E.ON Kernkraft GmbH, Hannover (Germany)

    2012-07-01

    The effect of chloride on the general corrosion and its potential impact on EAC crack initiation of low-alloy steel (German reactor pressure vessel steel 22 NiMoCr 3 7) in oxygenated high-temperature water were investigated. The general corrosion behavior was analyzed by exposure tests with either permanently increased chloride concentration levels or temporary chloride transients. The potential effect on EAC crack initiation was analyzed with pre-strained C-ring specimens and in SSRT (CERT) tests with slowly rising strain. Both kinds of tests were performed under simulated BWR conditions and with different chloride levels. The chloride concentrations of 5 to 50 ppb were chosen according to the action levels of the German water chemistry guideline for the reactor coolant of BWRs (VGB R401J, 2006). In all exposure tests, none of the pre-strained C-ring specimens showed crack initiation during up to 1000 hours of exposure time with up to 50 ppb chloride. Investigations of the oxide layer thickness after immersion testing revealed a decrease with increasing chloride concentration. As shown by post-test chemical analysis of the oxide layer composition by TOF-SIMS, this effect is most likely primarily due to adsorption of chloride on the oxide layer surface, since only very limited penetration of chloride into the oxide was detected. In contrast to the tests with C-ring specimens, where no crack initiation occurred, slightly accelerated crack initiation at lower elongation levels was observed at increasing chloride concentrations in SSRT tests under simulated BWR conditions using actively loaded specimens. In addition, SSRT specimens that were cyclically loaded at the oxide fracture elongation level were used to generate a continuous, exposure of bare metal to the environment by repeated fracture of the oxide. This loading pattern did not cause crack initiation at all chloride concentrations applied (up to 50 ppb). From these results, it may be concluded that at least

  19. Corrosion Behavior of Brass In Tio2 Nanofluids

    Science.gov (United States)

    Wu, Kai; Ge, Hong-Hua; Wang, Feng; Zhou, Hong-Wang

    2017-09-01

    Corrosion behavior of brass electrode in TiO2 nanofluids was analyzed using electrochemical impedance spectroscopy. The experimental results show that TiO2 nanoparticles promote corrosion of brass. The corrosion resistance of brass electrode decreases with the increase of the temperature of the TiO2 nanofluids. Sodium dodecyl benzene sulfonate (SDBS) is a dispersant in nanofluids and also appears corrosion inhibition to brass, and the corrosion inhibition enhances with the increase of SDBS concentration. The corrosion resistance of brass in TiO2 nanofluids would decrease when the concentration of dispersant SDBS exceeds a certain value.

  20. Effect of microstructure on the corrosion and deformation behavior of a newly developed 6Mn-5Cr-1.5Cu corrosion-resistant white iron

    Science.gov (United States)

    Rao, P. N. V. R. S. S. V. Prasada; Patwardhan, A. K.; Jain, N. C.

    1993-02-01

    An experimental study has been made of the effect of heat treatment on the transformation behavior of a 4.8 pct Cr white iron, alloyed with 6 pct Mn and 1.5 pct Cu, by employing optical metallography, X-ray diffractometry, and differential thermal analysis (DTA) techniques, with a view to assess the suitability of the different microstructures in resisting aqueous corrosion. The matrix microstructure in the as-cast condition, comprising pearlite + bainite/martensite, transformed to austenite on heat-treating at all the temperatures between 900 °C and 1050 °C. Increasing the soaking period at each of the heat-treating temperatures led to an increase in the volume fraction and stability of austenite. M3C was the dominant carbide present in the as-cast condition. On heat-treating, different carbides formed: M23C6 carbide was present on heat-treating at 900 °C and 950 °C; on heat-treating at 1000 °C, M7C3 formed and persisted even on heattreating at 1050 °C. The possible formation of M5C2 carbide in the as-cast and heat-treated conditions (900 °C and 950 °C) is also indicated. Dispersed carbides (DC), present in austenite up to 950 °C, mostly comprised M3C and M5C2. On stress relieving of the heat-treated samples, M7C3-type DC also formed. The hardness changes were found to be consistent with the micro-structural changes occurring on heat-treating. The as-cast state was characterized by a reasonable resistance to corrosion in 5 pct NaCl solution. On heat-treating, the corrosion resistance improved over that in the as-cast state. After 4 hours soaking, increasing the temperature from 900 °C to 1050 °C led to an improvement in corrosion resistance. However, after 10 hours soaking, corrosion resistance decreased on increasing the temperature from 900 °C to 950 °C and improved thereafter on increasing the heat-treating temperature. Deformation behavior responded to the microstructure on similar lines as the corrosion behavior. Although in an early stage of

  1. Phase equilibrium properties of binary aqueous solutions containing ethanediamine, 1,2-diaminopropane, 1,3-diaminopropane, or 1,4-diaminobutane at several temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Nouria Chiali-Baba [LATA2M, Laboratoire de Thermodynamique Appliquee et Modelisation Moleculaire, University AbouBekr Belkaid of Tlemcen, P.O. Box 119, Tlemcen 13000 (Algeria); Negadi, Latifa, E-mail: l_negadi@mail.univ-tlemcen.d [LATA2M, Laboratoire de Thermodynamique Appliquee et Modelisation Moleculaire, University AbouBekr Belkaid of Tlemcen, P.O. Box 119, Tlemcen 13000 (Algeria); Mokbel, Ilham; Jose, Jacques [LSA, Laboratoire des Sciences Analytiques, CNRS-UMR 5180, Universite Claude Bernard - Lyon I. 43, Bd du 11 Novembre 1918, Villeurbanne Cedex 69622 (France)

    2011-05-15

    Research highlights: Vapour pressures of ethanediamine (EDA), 1,2-diaminopropane, 1,3-diaminopropane (1,3-DAP), or 1,4-diaminobutane (1,4-DAB) aqueous solutions are reported between (293 and 363) K. The two first mixtures show negative azeotropic behaviour. The aqueous solutions of EDA, 1,2-DAP, or 1,3-DAP exhibit negative G{sup E} whereas the one containing 1,4-DAB shows either negative G{sup E} or sinusoidal shape for G{sup E}. - Abstract: The vapour pressures of {l_brace}ethanediamine (EDA) + water{r_brace}, {l_brace}1,2-diaminopropane (1,2-DAP) + water{r_brace}, {l_brace}1,3-diaminopropane (1,3-DAP) + water{r_brace} or {l_brace}1,4-diaminobutane (1,4-DAB) + water{r_brace} binary mixtures, and of pure EDA, 1,2-DAP, 1,3-DAP, 1,4-DAB, and water components were measured by means of two static devices at temperatures between (293 and 363) K. The data were correlated with the Antoine equation. From these data, the excess Gibbs function (G{sup E}) was calculated for several constant temperatures and fitted to a fourth-order Redlich-Kister equation using the Barker's method. The {l_brace}ethanediamine (EDA) + water{r_brace}, and {l_brace}1,2-diaminopropane (1,2-DAP) + water{r_brace} binary systems show negative azeotropic behaviour. The aqueous solutions of EDA, 1,2-DAP, or 1,3-DAP exhibit negative deviations in G{sup E} for all investigated temperatures over the whole composition range whereas the (1,4-DAB + water) binary mixture shows negative G{sup E} for temperatures (293.15 < T/K < 353.15) and a sinusoidal shape for G{sup E} at T = 363.15 K.

  2. Aircraft Corrosion

    Science.gov (United States)

    1981-08-01

    au traitement. micaniqus qui provoque une compression de surface - h1l’spplication i1’une double protection comportant oxydation snodique et...primaire anti-corrosion nitrosynthdtique pigmontie au chromate do zinc - une couche do peinture de finition nitrosynthdtique risistant aux huiles ...condition: - Touch-up of concerned fastener holes with chemical oxydation ; - Wet assembly of fasteners; - Application of a strontium chromate primer and

  3. Corrosion Testing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Corrosion Testing Facility is part of the Army Corrosion Office (ACO). It is a fully functional atmospheric exposure site, called the Corrosion Instrumented Test...

  4. A Galvanic Sensor for Monitoring the Corrosion Condition of the Concrete Reinforcing Steel: Relationship Between the Galvanic and the Corrosion Currents

    Directory of Open Access Journals (Sweden)

    Elsa Vaz Pereira

    2009-10-01

    Full Text Available This work reports a study carried out on the design and performance of galvanic and polarization resistance sensors to be embedded in concrete systems for permanent monitoring of the corrosion condition of reinforcing steel, aiming to establish a correlation between the galvanic currents, Igal, and the corrosion currents, Icorr, estimated from the polarization resistance, Rp. Sensors have been tested in saturated Ca(OH2 aqueous solutions, under a variety of conditions, simulating the most important parameters that can accelerate the corrosion of concrete reinforcing steel, such as carbonation, ingress of chloride ions, presence or absence of O2. For all the conditions, the influence of temperature (20 to 55 ºC has also been considered. From this study, it could be concluded that the galvanic currents are sensitive to the various parameters following a trend similar to that of the Rp values. A relationship between the galvanic and the corrosion current densities was obtained and the limiting values of the Igal, indicative of the state condition of the reinforcing steel for the designed sensor, were established.

  5. Effect of flue gas composition on deposit induced high temperature corrosion under laboratory conditions mimicking biomass firing. Part I: Exposures in oxidizing and chlorinating atmospheres

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Kiamehr, Saeed; Montgomery, Melanie

    2017-01-01

    In biomass fired power plants, deposition of alkali chlorides on superheaters, aswell as the presence of corrosive flue gas species, give rise to fast corrosion ofsuperheaters. In order to understand the corrosion mechanism under thiscomplex condition, the influence of the flue gas composition...... bothoxidizing and oxidizing-chlorinating atmospheres, and the resulting corrosionproducts were comprehensively studied with scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD)techniques. The results show that deposit-free samples suffer grain boundaryattack...... only in an oxidizing-chlorinating atmosphere, otherwise corrosionresults in formation of a duplex oxide. Corrosion attack on deposit-coatedsamples was higher than on deposit-free samples irrespective of the gaseousatmosphere. Specifically, severe volatilization of alloying elements occurred ondeposit...

  6. Apparent molar volumes and apparent molar heat capacities of aqueous N-acetyl-D-glucosamine at temperatures from 278.15 K to 368.15 K and of aqueous N-methylacetamide at temperatures from 278.15 K to 393.15 K at the pressure 0.35 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Swenson, D.M. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States); Ziemer, S.P. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States); Blodgett, M.B. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States); Jones, J.S. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States); Woolley, E.M. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States)]. E-mail: earl_woolley@byu.edu

    2006-12-15

    We determined apparent molar volumes V {sub {phi}} from densities measured with a vibrating-tube densimeter at 278.15 {<=} (T/K) {<=} 368.15 and apparent molar heat capacities C {sub p,{phi}} with a twin fixed-cell, differential, temperature-scanning calorimeter at 278.15 {<=} (T/K) {<=} 363.15 for aqueous solutions of N-acetyl-D-glucosamine at m from (0.01 to 1.0) mol . kg{sup -1} and at p = 0.35 MPa. We also determined V {sub {phi}} at 278.15 {<=} (T/K) {<=} 368.15 and C {sub p,{phi}} at 278.15 {<=} (T/K) {<=} 393.15 for aqueous solutions of N-methylacetamide at m from (0.015 to 1.0) mol . kg{sup -1} and at p = 0.35 MPa. Empirical functions of m and T for each compound were fitted to our results, which are then compared to those for N,N-dimethylacetamide. Estimated values of {delta}{sub r} V {sub m}(m, T) and {delta}{sub r} C {sub p,m}(m, T) for formation of aqueous N-acetyl-D-glucosamine from aqueous D-glucose and aqueous acetamide are calculated and discussed.

  7. All-fiber reflecting temperature probe based on the simplified hollow-core photonic crystal fiber filled with aqueous quantum dot solution.

    Science.gov (United States)

    Wu, Jian; Yin, Xiaojin; Wang, Wenyuan; Hong, Xueming; Du, Yu; Geng, Youfu; Li, Xuejin

    2016-02-10

    An all-fiber reflecting fluorescent temperature probe is proposed based on the simplified hollow-core photonic crystal fiber (SHC-PCF) filled with an aqueous CdSe/ZnS quantum dot solution. SHC-PCF is an excellent PCF used to fill liquid materials, which has low loss transmission bands in the visible wavelength range and enlarged core sizes. Both end faces of the SHC-PCF were spliced with multimode fiber after filling in order to generate a more stable and robust waveguide structure. The obtained temperature sensitivity dependence of the emission wavelength and the self-referenced intensity are 126.23 pm/°C and -0.007/°C in the temperature range of -10°C-120°C, respectively.

  8. Thermodynamic data for copper. Implications for the corrosion of copper under repository conditions

    Energy Technology Data Exchange (ETDEWEB)

    Puigdomenech, I. [Royal Inst. of Tech., Stockholm (Sweden); Taxen, C. [Swedish Corrosion Inst., Stockholm (Sweden)

    2000-08-01

    The stability of copper canisters has a central role in the safety concept for the planned nuclear spent fuel repository in Sweden. The corrosion of copper canisters will be influenced by the chemical and physical environment in the near-field of the repository, and thermodynamic equilibrium calculations provide the basis for understanding this system. Thermodynamic data have been selected in this work for solids and aqueous species in the system: Cu - H{sub 2}O - H{sup +} - H{sub 2} - F{sup -} - Cl{sup -} - S{sup 2-} - SO{sub 4}{sup 2-} - NO{sub 3}{sup -} - NO{sub 2}{sup -} - NH{sub 4}{sup +} PO{sub 4}{sup 3-} - CO{sub 3}{sup 2+} . For some reactions and compounds, for which no experimental information on temperature effects was available, entropy and heat capacity values have been estimated. The compiled data were used to calculate thermodynamic equilibria for copper systems up to 100 deg C. The stability of copper in contact with granitic groundwaters has been illustrated using chemical equilibrium diagrams, with he following main conclusions: Dissolved sulphide and O{sub 2} in groundwater are the most damaging components for copper corrosion. If available, HS{sup -} will react quantitatively with copper to form a variety of sulphides. However, sulphide concentrations in natural waters are usually low, because it forms sparingly soluble solids with transition metals, including Fe(II), which is wide-spread in reducing environments. Chloride can affect negatively copper corrosion. High concentrations (e.g., [Cl{sup -}]TOT > 60 g/l) may be unfavourable for the general corrosion of copper in combination with in the following circumstances: Low pH (< 4 at 25 deg C, or < 5 at 100 deg C). The presence of other oxidants than H{sup +}. The negative effects of Cl{sup -} are emphasised at higher temperatures. The chloride-enhancement of general corrosion may be beneficial for localised corrosion: pitting and stress corrosion cracking. The concept of redox potential, E

  9. Corrosion resistance of neodymium and dysprosium hydrides

    Science.gov (United States)

    Karakchieva, Natalia; Lyamina, Galina; Knyazeva, Elena; Sachkov, Victor; Kurzina, Irina; Pichugina, Alina; Vladimirov, Alexander; Kazantseva, Ludmila; Sachkova, Anna

    2017-11-01

    This paper describes the methods of obtaining hydrides of rare earth elements such as dysprosium and neodymium. The properties and corrosion resistance of these elements are investigated. A synthesis method of monophasic dysprosium and neodymium dihydrides is presented. Synthesized dihydrides are agglomerates with an average size of 3-50 µm and are formed by crystalline grains of a nanometer size. BET specific surface area, morphology, elemental analyses and composition of samples have been studied. Corrosion stability in aqueous solutions of hydrochloric acid and sodium hydroxide were studied. It was determined that both hydrides undergo hydrolysis in acid and alkaline mediums. Neodymium hydride is more stable to corrosion than dysprosium hydride, which is proved by its longer exposure to aggressive medium to hydrides. The formation of insoluble /poorly soluble products of corrosion can make a significant contribution to the process of powder dissolution.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-11-15

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

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

    Science.gov (United States)

    Nava, N.; Likhanova, N. V.; Olivares-Xometl, O.; Flores, E. A.; Lijanova, I. V.

    2011-11-01

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

  12. An experimental study on the internal corrosion of a subsea multiphase pipeline

    OpenAIRE

    Shangbi Peng; Zhaoxiong Zeng

    2015-01-01

    Based on the actual operational parameters of a subsea multiphase pipeline, an experimental study on the internal corrosion of a subsea multiphase pipeline was conducted in a dynamic, high-temperature autoclave, which had a similar environment to an actual field environment, using the partial pressure of CO2 (PCO2), velocity of the corrosion medium, temperature, corrosion time, and corrosion inhibitor as variables. The results show that CO2 resulted in severe localized corrosion and that the ...

  13. Uncertainty quantification methodologies development for stress corrosion cracking of canister welds

    Energy Technology Data Exchange (ETDEWEB)

    Dingreville, Remi Philippe Michel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bryan, Charles R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-09-30

    This letter report presents a probabilistic performance assessment model to evaluate the probability of canister failure (through-wall penetration) by SCC. The model first assesses whether environmental conditions for SCC – the presence of an aqueous film – are present at canister weld locations (where tensile stresses are likely to occur) on the canister surface. Geometry-specific storage system thermal models and weather data sets representative of U.S. spent nuclear fuel (SNF) storage sites are implemented to evaluate location-specific canister surface temperature and relative humidity (RH). As the canister cools and aqueous conditions become possible, the occurrence of corrosion is evaluated. Corrosion is modeled as a two-step process: first, pitting is initiated, and the extent and depth of pitting is a function of the chloride surface load and the environmental conditions (temperature and RH). Second, as corrosion penetration increases, the pit eventually transitions to a SCC crack, with crack initiation becoming more likely with increasing pit depth. Once pits convert to cracks, a crack growth model is implemented. The SCC growth model includes rate dependencies on both temperature and crack tip stress intensity factor, and crack growth only occurs in time steps when aqueous conditions are predicted. The model suggests that SCC is likely to occur over potential SNF interim storage intervals; however, this result is based on many modeling assumptions. Sensitivity analyses provide information on the model assumptions and parameter values that have the greatest impact on predicted storage canister performance, and provide guidance for further research to reduce uncertainties.

  14. Application of E{sub h}-pH diagram for room temperature precipitation of zinc stannate microcubes in an aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hinai, Ashraf T., E-mail: ashraf@squ.edu.om [Department of Chemistry, College of Science, Sultan Qaboos University, 123, Alkhoud (Oman); Al-Hinai, Muna H. [Department of Chemistry, College of Science, Sultan Qaboos University, 123, Alkhoud (Oman); Water Research Center, Sultan Qaboos University, 123, Alkhoud (Oman); Dutta, Joydeep, E-mail: dutta@squ.ed.om [Water Research Center, Sultan Qaboos University, 123, Alkhoud (Oman)

    2014-01-01

    Graphical abstract: - Highlights: • One pot aqueous synthesis of zinc stannate (ZnSnO{sub 3}) particles at low temperature. • Synthesis designed with the assistance of potential-pH diagram. • ZnSnO{sub 3} estimated to be stable between pH 8 and 12 was used for synthesis of the particles. • ZnSnO{sub 3}·3H{sub 2}O were formed during the precipitation of zinc stannate. - Abstract: Potential-pH diagram assisted-design for controlled precipitation is an attractive method to obtain engineered binary and ternary oxide particles. Aqueous synthesis conditions of zinc stannate (ZnSnO{sub 3}) particles at low temperature were formulated with the assistance of potential-pH diagram. The pH of a solution containing stoichiometric amounts of Zn{sup 2+} and Sn{sup 4+} was controlled for the precipitation in a one pot synthesis step at room temperature (25 °C). The effect of the concentration of the reactants on the particle size was studied by varying the concentration of the precursor (Zn{sup 2+} + Sn{sup 4+}) solution. Scanning electron micrographs show that the particles are monodispersed micron sized cubes formed by the self-organization of nano-sized crystallites. The obtained microcubes characterized by X-ray Diffraction and thermo gravimetric analysis (TGA) show that the particles are in ZnSnO{sub 3}·3H{sub 2}O form.

  15. EFFECT OF TEMPERATURE AND CONCENTRATION ON THE VISCOSITY OF AQUEOUS SOLUTIONS OF 3-AMINOPROPANOIC ACID, 4-AMINOBUTANOIC ACID, 5-AMINOPENTANOIC ACID, 6-AMINOHEXANOIC ACID

    Directory of Open Access Journals (Sweden)

    Carmen María Romero

    2011-12-01

    Full Text Available In this work we present the effect of temperatureon the viscosities of aqueous solutionsof 3-aminopropanoic acid, 4-aminobutanoicacid, 5-aminopentanoic acidand 6-aminohexanoic acid as a functionof concentration. The experimental measurementswere done from 293.15 K to308.15 K. At each temperature the experimentaldata were fi tted to the Tsangaris-Martin equation and the B viscosity coefficient was determined. The dependenceof the B coeffi cients on the number ofcarbon atoms of the amino acids is linear,so the contribution of polar and apolargroups was established. The results areinterpreted in terms of amino acid hydration.

  16. Properties of L-ascorbic acid in water and binary aqueous mixtures of D-glucose and D-fructose at different temperatures

    Science.gov (United States)

    Sharma, Ravi; Thakur, R. C.; Sani, Balwinder; Kumar, Harsh

    2017-12-01

    Using density and sound velocity partial molar volumes, partial molar adiabatic compressibilities, partial molar expansibilities and structure of L-ascorbic acid have been determined in water and aqueous mixtures of D-glucose and D-fructose at different concentrations and temperatures. Masson's equation was used to analyze the measured data. The obtained parameters have been interpreted in terms of solute-solute and solute-solvent interactions. It is found that the L-ascorbic acid acts as structure breaker in water as well in binary studied mixtures.

  17. Stress corrosion cracking of Ti-8Al-1 Mo-1V in molten salts

    Science.gov (United States)

    Smyrl, W. H.; Blackburn, M. J.

    1975-01-01

    The stress corrosion cracking (SCC) behavior of Ti-8Al-1 Mo-1V has been studied in several molten salt environments. Extensive data are reported for the alloy in highly pure LiCl-KCl. The influence of the metallurgical heat treatment and texture, and the mechanical microstructure show similarities with aqueous solutions at lower temperature. The fracture path and cracking modes are also similar to that found in other environments. The influence of H2O and H(-) in molten LiCl-KCl lead to the conclusion that hydrogen does not play a major role in crack extension in this environment.

  18. A study on the improvement of corrosion resistance of fuel cladding by ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hyuk Sang; Lee, Sung Joon; Kim, Joon Shick; Suh, Min Suk; Choi, Eun Ae [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1997-07-01

    Effects of various ion implantation conditions on the composition, microstructure and corrosion resistance of implanted Zircaloy-4 were examined. Nitrogen implantations into the Zircaloy-4 were performed under conditions of varying the ion dose from 3 x 10{sup 17} to 1.2 x 10{sup 18} ions/cm{sup 2} and of varying the substrate temperatures from 100 to 500 deg C by controlling the current density of ion beam. Also, either Cr or Nb were deposited on Zircaloy-4 by sputtering method (deposited thickness : 500 A) and then was irradiated by 120 keV Ar{sup +} ions up to 5 x 10{sup 17} Ar{sup +}/cm{sup 2} at 200 deg C. 1. The resistance to localized corrosion Zircaloy-4 in 4 M NaCl at80 deg C and the resistance to general corrosion Zircaloy-4 in 1 M H{sub 2}SO{sub 4} at 20 deg C were significantly improved with nitrogen implantation as confirmed by both the increase in the pitting potential and the decrease in the passive current density. The improvement of corrosion resistance of Zircaloy-4 in low temperature aqueous solution was associated with the formation of compound layers of ZrO{sub 2}+ZrN during the implantation. Optimum implantation condition is 200 {approx} 300 deg C, 1x10{sub 18} N ions/cm{sub 2}. 2. The corrosion resistance of Zircaloy-4 in high temperature environment (350 deg C, 16.5 MPa pure water and 350 deg C, 16.5 MPa 0.1 M LiOH solution) was increased when implanted at substrate temperature 400 deg C. The weight gain for nitrogen-implanted Zircaloy decreased compared to the unimplanted. It is thought that the protective tetragonal ZrO{sub 2} formed during the implantation improved the resistance to high temperature corrosion. Optimum implantation condition is 400 deg C, 4 x 10{sub 17} N ions/cm{sub 2}. 3. The corrosion resistance of Zircaloy-4 water at 350 deg C was increased by Cr and Nb surface alloying. The weight gain for surface alloyed Zircaloy-4 decreased compared to the as-received. (Author) 75 refs., 6 tabs., 47 figs.

  19. Study of fluoride corrosion of nickel alloys

    Science.gov (United States)

    Gunther, W. H.; Steindler, M. J.

    1969-01-01

    Report contains the results of an investigation of the corrosion resistance of nickel and nickel alloys exposed to fluorine, uranium hexafluoride, and volatile fission product fluorides at high temperatures. Survey of the unclassified literature on the subject is included.

  20. New corrosion issues in gas sweetening plants

    Energy Technology Data Exchange (ETDEWEB)

    Asperger, R.G. (CLI International and Asperger Technologies, Houston, TX (United States))

    Gas treating plants are experiencing corrosion problems which impact on efficiency and safety. While general corrosion is not particularly hazardous in the gas processing industry, local corrosion is very dangerous since it has several different mechanisms, all of which have dangerously high rates, and it occurs at locations which are hard to find and hard to predict. A newly discovered, velocity-dependent type of corrosion is reported. It is related to yet-undefined species which cause excessively high corrosion in areas of turbulence. This accelerated corrosion is not due to erosion or cavitation, but to a diffusion-limited reaction accelerated by turbulence. A full-flow test loop was built to evaluate the corrosiveness of gas plant solutions at their normal temperature and flow rates. Test runs were conducted with Co[sub 2]-loaded amine solutions for periods of 12 days. Carbon steel specimens mounted in the test loop were examined and corrosion rates calculated. Chromium alloys were shown to be attacked by corrodents in the low-velocity part of the loop and very aggressively attacked in the high-velocity part. The tests demonstrate the need for rigorous monitoring of corrosion in areas of higher velocity such as piping elbows and other points of turbulence. 5 refs., 2 figs., 3 tabs.

  1. Atmospheric Corrosion on Steel Studied by Conversion Electron Moessbauer Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi, Akio; Kobayashi, Takayuki [Shiga University of Medical Science, Department of Physics (Japan)

    2004-12-15

    In order to investigate initial products on steel by atmospheric corrosion, conversion electron Moessbauer measurements were carried out at temperatures between 15 K and room temperature. From the results obtained at low temperatures, it was found that the corrosion products on steel consisted of ferrihydrite.

  2. Hot Corrosion in Gas Turbines.

    Science.gov (United States)

    1983-04-27

    in hot corrosion under some circumstances, because its role seems to be principally through reduction of NagSO, or erosion by pyrolytic graphite...same morphology could be produced either by spray -coating with NaxSO, or by diffusing NIS into the cut- edge region under argon at temperature and then

  3. Stable solid and aqueous H2CO3 from CO2 and H2O at high pressure and high temperature

    Science.gov (United States)

    Wang, Hongbo; Zeuschner, Janek; Eremets, Mikhail; Troyan, Ivan; Willams, Jonathan

    2016-01-01

    Carbonic acid (H2CO3) forms in small amounts when CO2 dissolves in H2O, yet decomposes rapidly under ambient conditions of temperature and pressure. Despite its fleeting existence, H2CO3 plays an important role in the global carbon cycle and in biological carbonate-containing systems. The short lifetime in water and presumed low concentration under all terrestrial conditions has stifled study of this fundamental species. Here, we have examined CO2/H2O mixtures under conditions of high pressure and high temperature to explore the potential for reaction to H2CO3 inside celestial bodies. We present a novel method to prepare solid H2CO3 by heating CO2/H2O mixtures at high pressure with a CO2 laser. Furthermore, we found that, contrary to present understanding, neutral H2CO3 is a significant component in aqueous CO2 solutions above 2.4 GPa and 110 °C as identified by IR-absorption and Raman spectroscopy. This is highly significant for speciation of deep C-O-H fluids with potential consequences for fluid-carbonate-bearing rock interactions. As conditions inside subduction zones on Earth appear to be most favorable for production of aqueous H2CO3, a role in subduction related phenomena is inferred.

  4. Fundamental aspects of stress corrosion cracking of copper relevant to the Swedish deep geologic repository concept

    Energy Technology Data Exchange (ETDEWEB)

    Bhaskaran, Ganesh; Carcea, Anatolie; Ulaganathan, Jagan; Wang, Shengchun; Huang, Yin; Newman, Roger C. [Dept. of Chemical Engineering and Applied Chemistry, Univ. of Toronto, Toronto (Canada)

    2013-03-15

    Phosphorus-doped oxygen-free copper will be used as the outer barrier in canisters that will contain spent nuclear fuel in the proposed Swedish underground repository. The possibility of stress corrosion cracking (SCC) is a concern, in view of isolated reports of cracking or intergranular corrosion of pure copper in sulfide solutions. This concern was addressed in the present work using copper tensile specimens provided by SKB. Methods included slow strain rate testing, constant strain tensile testing, electrochemical and surface analytical studies of corrosion products, and electron backscatter diffraction analysis of grain orientation effects on corrosion. The base solutions were prepared from NaCl or synthetic sea water with addition of varying amounts of sodium sulfide at room temperature and 80 degree Celsius. No SCC was found in any of the testing, for a range of sulfide concentrations from 5-50 mM at room temperature or 8 C, including tests where small anodic or cathodic potential displacements were applied from the open-circuit (corrosion) potential. Neither was SCC found in constant-strain immersion testing with very large strain. The Cu2S corrosion product is generally very coarse, fragile, and easily spalled off in severe corrosion environments, i.e. high sulfide concentration, high temperature, less perfect de aeration, etc. But it could also consist of very fine grains, relatively compact and adherent, on particular grain orientations when it was formed on an electro polished surface in a very well-deaerated solution. These orientations have not yet been identified statistically, although some preference for thin, adherent films was noted on orientations close to (100). The notion that the corrosion reaction is always controlled by inward aqueous-phase diffusion of sulfide may thus not be unconditionally correct for this range of sulfide concentrations; however it is hard to distinguish the role of diffusion within pores in the film. In the actual

  5. Systematic Microstructural and Corrosion Performance Evaluation of CK-3MCuN and CN-3MN High Molybdenum Stainless Steel Castings

    Energy Technology Data Exchange (ETDEWEB)

    C.D. Lundin; S. Wen; W. Liu; G. Zhou

    2001-10-01

    High molybdenum austenitic stainless steel castings are widely accepted for their high strength, excellent weldability, and good corrosion resistance over a wide range of temperatures in highly oxidizing aqueous and gaseous media in chemical processing and other environments. With their desirable performance, high molybdenum austenitic stainless steel castings are increasingly applied in industry in a similar manner as wrought materials. In general, cast and wrought stainless and high alloy steels are anticipated to possess equivalent resistance to corrosive media, and they are frequently used in conjunction with each other. However, alloying element segregation usually is more evident in castings than in wrought counterparts. Segregation of alloying elements can lead to the formation of secondary phases, such as sigma. Mechanical properties and especially the corrosion resistance of castings may be affected by the secondary phases. In addition, improper heat treatment procedures c an also lead to the formation of carbides and secondary phases in high alloy and austenitic stainless steels.

  6. Cast iron deterioration with time in various aqueous salt solutions

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The changes with time in the corrosion rate and corrosion current density on a cast iron electrode in various aqueous salt solutions have been carried out using total immersion test and potentiostatic polarization curves. The concentration of salts taken is expected to be present in potable water. The relative ...

  7. Effect of flue gas composition on deposit induced high temperature corrosion under laboratory conditions mimicking biomass firing. Part II: Exposures in SO2 containing atmospheres

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Kiamehr, Saeed; Montgomery, Melanie

    2017-01-01

    In biomass fired power plants, the fast corrosion of superheaters is facilitatedby the presence of corrosive flue gas species, for example, SO2, which arereleased during combustion. To understand the role of the gas species on thecorrosion process, comparative laboratory exposures of deposit (KCl......)-coatedand deposit-free austenitic stainless steel (TP 347H FG) samples to gas mixturescontaining SO2 was carried out, under conditions relevant to biomass-firing.Exposures were conducted isothermally at 560 8C for 72 h, in oxidizingsulphidizing,and oxidizing-sulphidizing-chlorinating gas mixtures containing60 ppmv...... SO2. Scanning electron microscopy (SEM), energy dispersive X-rayspectroscopy (EDS) and X-ray diffraction (XRD) techniques werecomplimentarily applied to characterize the resulting corrosion products. Apartially molten K2SO4-layer formed on KCl coated specimens, and corrosionresulted in localized...

  8. THE EFFECT OF ANNEALING TEMPERATURES AFTER THERMOMECHANICAL PROCESS TO THE CORROSION BEHAVIOR OF Ni3(Si,Ti IN SULFATE SOLUTION

    Directory of Open Access Journals (Sweden)

    Gadang Priyotomo

    2015-03-01

    Full Text Available The corrosion behaviour of the intermetallic compounds Ni3(Si,Ti (L12: single phase, has been investigated using an immersion test, polarization method, scanning electron microscope in 0.5 kmol/m3 H2SO4 solution at 303 K.  Moreover, the corrosion behaviour of austenitic stainless steel type 304 was studied under the same experimental conditions as reference. It was found that the intergranular attack and uniform attack were observed on Ni3(Si,Ti after thermomechanical and annealing processes (1173K and 1273K respectively in the immersion test. From the immersion test and polarization curves, all annealed Ni3(Si,Ti had less corrosion resistance compared to type 304. In addition, Ni3(Si,Ti was difficult to form a stable passive film, but not for type 304.

  9. Nanoparticles of Low-Valence Vanadium Oxyhydroxides: Reaction Mechanisms and Polymorphism Control by Low-Temperature Aqueous Chemistry

    OpenAIRE

    Besnardiere, Julie; Petrissans, Xavier; Ribot, François; Briois, Valérie; Surcin, Christine; Morcrette, Mathieu; Buissette, Valérie; Le Mercier, Thierry; Cassaignon, Sophie; Portehault, David

    2016-01-01

    International audience; An aqueous synthetic route at 95 °C is developed to reach selectively three scarcely reported vanadium oxyhydroxides. Häggite V2O3(OH)2, Duttonite VO(OH)2, and Gain’s hydrate V2O4(H2O)2 are obtained as nanowires, nanorods, and nanoribbons, with sizes 1 order of magnitude smaller than previously reported. X-ray absorption spectroscopy provides evidence that vanadium in these phases is V+IV. Combined with FTIR, XRD, and electron microscopy, it yields the first insights i...

  10. Hydration and Hydrogen Bond Network of Water during the Coil-to-Globule Transition in Poly(N-isopropylacrylamide) Aqueous Solution at Cloud Point Temperature.

    Science.gov (United States)

    Shiraga, Keiichiro; Naito, Hirotaka; Suzuki, Tetsuhito; Kondo, Naoshi; Ogawa, Yuichi

    2015-04-30

    Aqueous solutions of poly(N-isopropylacrylamide), P-NIPAAm, exhibit a noticeable temperature responsive change in molecular conformation at a cloud point temperature (Tcp). As the temperature rises above Tcp, the extended coil-like P-NIPAAm structure changes into a swollen globule-like conformation as hydration levels decrease and hydrophobic interactions increase. Though water plays an important role in this coil-to-globule transition of P-NIPAAm, the behavior of water molecules and the associated hydrogen-bond (HB) network of the surrounding bulk water are still veiled in uncertainty. In this study, we elucidate changes in the hydration state and the dynamical structure of the water HB network of P-NIPAAm aqueous solutions during the coil-to-globule transition by analyzing the complex dielectric constant in the terahertz region (0.25-12 THz), where bulk water reorientations and intermolecular vibrations of water can be selectively probed. The structural properties of the water HB network were examined in terms of the population of the non-HB water molecules (not directly engaged in the HB network or hydrated to P-NIPAAm) and the tetrahedral coordination of the water molecules engaged in the HB network. We found the hydration number below Tcp (≈10) was decreased to approximately 6.5 as temperature increased, in line with previous studies. The HB network of bulk water becomes more structured as the coil-to-globule phase transition takes place, via decreases in non-HB water and reduction in the orderliness of the tetrahedral HB architecture. Together these results indicate that the coil-to-globule transition is associated with a shift to hydrophobic-dominated interactions that drive thermoresponsive structural changes in the surrounding water molecules.

  11. Grain boundary selective oxidation and intergranular stress corrosion crack growth of high-purity nickel binary alloys in high-temperature hydrogenated water

    Energy Technology Data Exchange (ETDEWEB)

    Bruemmer, S. M.; Olszta, M. J.; Toloczko, M. B.; Schreiber, D. K.

    2018-02-01

    The effects of alloying elements in Ni-5at%X binary alloys on intergranular (IG) corrosion and stress corrosion cracking (SCC) have been assessed in 300-360°C hydrogenated water at the Ni/NiO stability line. Alloys with Cr or Al additions exhibited grain boundary oxidation and IGSCC, while localized degradation was not observed for pure Ni, Ni-Cu or Ni-Fe alloys. Environment-enhanced crack growth was determined by comparing the response in water and N2 gas. Results demonstrate that selective grain boundary oxidation of Cr and Al promoted IGSCC of these Ni alloys in hydrogenated water.

  12. Accelerated Corrosion Testing

    Science.gov (United States)

    1982-12-01

    Treaty Organization, Brussels, 1971), p. 449. 14. D. 0. Sprowls, T. J. Summerson, G. M. Ugianski, S. G. Epstein, and H. L. Craig , Jr., in Stress...National Association of Corrosion Engineers Houston, TX, 1972). 22. H. L. Craig , Jr. (ed.), Stress Corrosion-New Approaches, ASTM-STP- 610 (American...62. M. Hishida and H. Nakada, Corrosion 33 (11) 403 (1977). b3. D. C. Deegan and B. E. Wilde, Corrosion 34 (6), 19 (1978). 64. S. Orman, Corrosion Sci

  13. A STUDY OF CORROSION AND STRESS CORROSION CRACKING OF CARBON STEEL NUCLEAR WASTE STORAGE TANKS

    Energy Technology Data Exchange (ETDEWEB)

    BOOMER, K.D.

    2007-08-21

    The Hanford reservation Tank Farms in Washington State has 177 underground storage tanks that contain approximately 50 million gallons of liquid legacy radioactive waste from cold war plutonium production. These tanks will continue to store waste until it is treated and disposed. These nuclear wastes were converted to highly alkaline pH wastes to protect the carbon steel storage tanks from corrosion. However, the carbon steel is still susceptible to localized corrosion and stress corrosion cracking. The waste chemistry varies from tank to tank, and contains various combinations of hydroxide, nitrate, nitrite, chloride, carbonate, aluminate and other species. The effect of each of these species and any synergistic effects on localized corrosion and stress corrosion cracking of carbon steel have been investigated with electrochemical polarization, slow strain rate, and crack growth rate testing. The effect of solution chemistry, pH, temperature and applied potential are all considered and their role in the corrosion behavior will be discussed.

  14. CORROSION OF LEAD SHIELDING IN NUCLEAR MATERIALS PACKAGES

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, K; Kerry Dunn, K; Joseph Murphy, J

    2008-07-18

    Inspection of United States-Department of Energy (US-DOE) model 9975 nuclear materials shipping package revealed corrosion of the lead shielding that was induced by off-gas constituents from organic components in the package. Experiments were performed to determine the corrosion rate of lead when exposed to off-gas or degradation products of these organic materials. The results showed that the room temperature vulcanizing (RTV) sealant was the most corrosive organic species used in the construction of the packaging, followed by polyvinyl acetate (PVAc) glue. Fiberboard material, also used in the construction of the packaging induced corrosion to a much lesser extent than the PVAc glue and RTV sealant, and only in the presence of condensed water. The results indicated faster corrosion at temperatures higher than ambient and with condensed water. In light of these corrosion mechanisms, the lead shielding was sheathed in a stainless steel liner to mitigate against corrosion.

  15. Elevated Temperature Corrosion Studies of AlCrN and TiAlN Coatings by PAPVD on T91 Boiler Steel

    Science.gov (United States)

    Goyal, Lucky; Chawla, Vikas; Hundal, Jasbir Singh

    2017-11-01

    The present investigation discusses the hot corrosion behavior of AlCrN and TiAlN nano-coatings on T91 boiler steel by PAPVD process subjected to molten salt of Na2SO4-60%V2O5 at 900 °C for 50 cycles. Surface and cross-sectional studies were performed by AFM, SEM/EDS and XRD techniques to understand the corrosion kinetics and mechanism. T91 bare boiler steel as well as TiAlN-coated specimen has shown higher internal oxidation as well as weight gain. The better corrosion resistance of AlCrN-coated specimen has been observed by virtue of higher availability of Cr and Al in the oxide scale as well as adherent and dense coating. The betterment of AlCrN coating can be attributed to low internal oxidation as well as movement of Cr and Al toward oxide scale to form protective corrosion barriers.

  16. Nanoparticles of Low-Valence Vanadium Oxyhydroxides: Reaction Mechanisms and Polymorphism Control by Low-Temperature Aqueous Chemistry.

    Science.gov (United States)

    Besnardiere, Julie; Petrissans, Xavier; Ribot, François; Briois, Valérie; Surcin, Christine; Morcrette, Mathieu; Buissette, Valérie; Le Mercier, Thierry; Cassaignon, Sophie; Portehault, David

    2016-11-07

    An aqueous synthetic route at 95 °C is developed to reach selectively three scarcely reported vanadium oxyhydroxides. Häggite V2O3(OH)2, Duttonite VO(OH)2, and Gain's hydrate V2O4(H2O)2 are obtained as nanowires, nanorods, and nanoribbons, with sizes 1 order of magnitude smaller than previously reported. X-ray absorption spectroscopy provides evidence that vanadium in these phases is V+IV. Combined with FTIR, XRD, and electron microscopy, it yields the first insights into formation mechanisms, especially for Häggite and Gain's hydrate. This study opens the way for further investigations of the properties of novel V+IV (oxyhydr)oxides nanostructures.

  17. Conditions and mechanisms for the formation of nano-sized Delafossite (CuFeO2) at temperatures ≤90 °C in aqueous solution

    Science.gov (United States)

    John, Melanie; Heuss-Aßbichler, Soraya; Ullrich, Aladin

    2016-02-01

    In this study, we present the mechanism of CuFeO2 formation in aqueous solution at low temperatures ≤90 °C, using sulfate salts as reactants. Furthermore, we demonstrate the influence of experimental conditions (alkalization, reaction and ageing temperature and time) on the synthesized nanoparticles. In all cases, GR-SO4, a Fe(II-III) layered double hydroxysulphate (Fe2+4Fe3+2(OH)12·SO4) and Cu2O precipitate first. During further OH- supply GR-SO4 oxidizes and forms Fe10O14(OH)2, Cu2O and CuFeO2 crystals. Due to the high pH further CuFeO2 crystals grow at the cost of the unstable intermediate products. The reaction rate increases with increasing ageing temperature, reaction pH and, in particular, NaOH concentrations in the solution. As a result, highly crystalline CuFeO2 (3R and 2H polytypes) nanoparticles showing hexagonal morphology can be synthesized at 70 °C within 10 h or at 50 °C within 1 week. The formation of 2H polytype is favored by additional OH- supply during the pH-stat time and rather low temperatures.

  18. Aqueous chemical route synthesis and the effect of calcination temperature on the structural and optical properties of ZnO nanoparticles

    Directory of Open Access Journals (Sweden)

    Mohammad Ramzan Parra

    2014-10-01

    Full Text Available This article reports the controlled size of ZnO nanoparticles synthesized via simple aqueous chemical route without the involvement of any capping agent. The effect of different calcination temperatures on the size of the ZnO nanoparticles was investigated. X-ray diffraction (XRD results indicated that all the samples have crystalline wurtzite phase, and peak broadening analysis was used to evaluate the average crystallite size and lattice strain using Scherrer's equation and Williamson–Hall (W–H method. Morphology and elemental compositions were investigated using atomic force microscopy (AFM and scanning electron microscopy (SEM with energy-dispersive X-ray (EDX spectroscopy. The average crystallite size of ZnO nanoparticles estimated from Scherrer's formula and W–H analysis was found to increase with the increase in calcination temperature. These results were in good agreement with AFM results. Optical properties were investigated using UV–vis spectroscopy in diffused reflectance (DR mode, with a sharp increase in reflectivity at 375 nm and the material has a strong reflective characteristic after 420 nm at 500 °C calcination temperature. Furthermore, photoluminescence spectroscopic results revealed intensive ultraviolet (UV emission with reduced defect concentrations and a slight shifting in band gap energies with increased calcination temperature from 200 °C to 500 °C. This study suggests that the as-prepared ZnO nanoparticles with bandgap tunability might be utilized as window layer in optoelectronic devices.

  19. Steam generator corrosion 2007; Dampferzeugerkorrosion 2007

    Energy Technology Data Exchange (ETDEWEB)

    Born, M. (ed.)

    2007-07-01

    Between 8th and 9th November, 2007, SAXONIA Standortentwicklungs- und -verwertungsgesellschaft GmbH (Freiberg, Federal Republic of Germany) performed the 3rd Freiberger discussion conference ''Fireside boiler corrosion''. The topics of the lectures are: (a) Steam generator corrosion - an infinite history (Franz W. Alvert); (b) CFD computations for thermal waste treatment plants - a contribution for the damage recognition and remedy (Klaus Goerner, Thomas Klasen); (c) Experiences with the use of corrosion probes (Siegfried R. Horn, Ferdinand Haider, Barbara Waldmann, Ragnar Warnecke); (d) Us