WorldWideScience
1

Protection of Steel Constructions from Corrosive Destruction  

International Science & Technology Center (ISTC)

Development of the New Effective Sacrificial Anodes on the Basis of Secondary Aluminum for Protection of Steel Constructions of Hydropower Stations and Heat Stations of the Republic of Tajikistan from Corrosion Destruction

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Cathodic corrosion protection of steel pipes; Kathodischer Korrosionsschutz von Rohrleitungsstaehlen  

Energy Technology Data Exchange (ETDEWEB)

The cathodic corrosion protection has been proven excellently in the practical use for buried steel pipelines. This is evidenced statistically by a significantly less frequency of loss compared to non-cathodically protected pipelines. Based on thermodynamic considerations, the authors of the contribution under consideration describe the operation of the cathodic corrosion protection and regular adjustment of the electrochemical potential at the interface steel / soil in practical use. Subsequently, the corrosion scenarios are discussed that may occur when an incorrect setting of the potential results from an operation over several decades. This incorrect setting also can be caused by the failure of individual components of the corrosion protection.

Buechler, Markus [SGK Schweizerische Gesellschaft fuer Korrosionsschutz, Zuerich (Switzerland); Schoeneich, Hanns-Georg [Open Grid Europe, Essen (Germany)

2011-07-01

3

Guidelines for the Protection of Steel Piles : Corrosive Marine Environment  

OpenAIRE

The corrosion of steel is a common phenomenon. In a marine environment, steel is corroded at an accelerated rate due to the atmospheric conditions. To combat this corrosion, steel piles are coated in order to protect them. As a major supplier of steel piles, Rautaruukki Oyj (Ruukki) commissioned this project in order to streamline their coating process. Currently Ruukki supplies a different coating system for almost every job; the aim of the project was to reduce the number of systems used to...

Rhodes, Graham

2011-01-01

4

Corrosion protection by sonoelectrodeposited organic films on zinc coated steel.  

Science.gov (United States)

A variety of coatings based on electrosynthesized polypyrrole were deposited on zinc coated steel in presence or absence of ultrasound, and studied in terms of corrosion protection. Cr III and Cr VI commercial passivation were used as references. Depth profiling showed a homogeneous deposit for Cr III, while SEM imaging revealed good surface homogeneity for Cr VI layers. These chromium-based passivations ensured good protection against corrosion. Polypyrrole (PPy) was also electrochemically deposited on zinc coated steel with and without high frequency ultrasound irradiation in aqueous sodium tartrate-molybdate solution. Such PPy coatings act as a physical barrier against corrosive species. PPy electrosynthesized in silent conditions exhibits similar properties to Cr VI passivation with respect to corrosion protection. Ultrasound leads to more compact and more homogeneous surface structures for PPy, as well as to more homogeneous distribution of doping molybdate anions within the film. Far better corrosion protection is exhibited for such sonicated films. PMID:22516111

Et Taouil, Abdeslam; Mahmoud, Mahmoud Mourad; Lallemand, Fabrice; Lallemand, Séverine; Gigandet, Marie-Pierre; Hihn, Jean-Yves

2012-11-01

5

Corrosion protection  

Science.gov (United States)

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.

Brown, Donald W.; Wagh, Arun S.

2003-05-27

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Wire-Arc-Sprayed Aluminum Protects Steel Against Corrosion  

Science.gov (United States)

Aluminum coatings wire-arc sprayed onto steel substrates found effective in protecting substrates against corrosion. Coatings also satisfy stringent requirements for adhesion and flexibility, both at room temperature and at temperatures as low as liquid hydrogen. Developed as alternatives to corrosion-inhibiting primers and paints required by law to be phased out because they contain and emit such toxic substances as chromium and volatile organic compounds.

Zimmerman, Frank R.; Poorman, Richard; Sanders, Heather L.; Mckechnie, Timothy N.; Bonds, James W., Jr.; Daniel, Ronald L., Jr.

1995-01-01

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Studies and research work on the reinforcement steel and concrete surface corrosion protection methods  

OpenAIRE

Methods for reinforcement steel corrosion protection and concrete surface protection are analyzed. Knowing the corrosion process mechanism reinforcement steel can be protected by different protection methods even in the presence of crevices larger than those anticipated by design. The selection of the corrosion protection method depends on the reduction level of the reinforcement steel corrosion which in its turn is determined by the atmospheric conditions. The selection of the accelerated co...

Gheorghe Croitoru

2013-01-01

8

Inorganic coatings on stainless steel for protection against crevice corrosion  

International Nuclear Information System (INIS)

In order to create protection against crevice corrosion stainless steel test specimens of type 316 steel with various inorganic coatings applied on crevice surfaces were tested for 3-50 months at 25 and 30 degree C in natural seawater containing 0.2-1.5 ppm free chlorine. Various metallic coatings, Ni base alloys with Cr and Mo, Ni with W, pure Ag and pure Mo, as well as ceramic coatings - Cr2O3, TiO2 and Al2O3 - were studied. All the coatings tested, except pure Molybdenum applied by plasma spraying in a max 0.1 mm thick layer were found to promote crevice corrosion of the stainless steel. A significant reduction of the crevice corrosion susceptibility was obtained with Molybdenum. The result is considered promising enough to justify full scale tests in seawater on flange joints of pipes, valves or pumps. (author)

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Characterisation of corrosion products on pipeline steel under cathodic protection  

Energy Technology Data Exchange (ETDEWEB)

Onshore gas transmission lines are conjointly protected against external corrosion by cathodic protection (CP) and organic coatings. If both protection systems are simultaneously faulty, the pipe may be subjected to local loss of protection criteria. Consequently, the development of a corrosion due to the ground intrinsic corrosiveness may occur. To guarantee an optimal and safe use of its 31000 km buried gas transmission network, Gaz de France regularly inspects its pipelines. When indications of metal damage are suspected, excavations are realized to carry out a finer diagnosis and, if necessary, to repair. Whenever, corrosions are encountered, although it occurs very scarcely, it is necessary to evaluate its degree of gravity: activity, mechanism, and kinetics. Among corrosion defects, it is indeed essential to differentiate those active, from those older inactive at the time of excavation, since those last ones may possibly have been annihilated, by a PC reinforcement for instance. Eventually, the identification of the corrosion mechanism and its associated rate will provide an assessment of the risks encountered by other sections of the pipeline similar to that excavated. This study investigates to what extent the degree of gravity (activity, kinetics) of a corrosion can be determined by the characterization and identification of its associated corrosion products. Moreover, it will attempt to relate it to the close environment features as well as to the operating conditions of the pipe. The preliminary results presented in this paper consist in a laboratory study of the time evolution of corrosion products formed on the surface of ordinary low carbon steel samples. The specimens have been previously subjected to various polarization conditions in various aqueous media. The selected solutions are characteristic of ground waters. The main parameters considered for the definition of the media were its initial chemical composition, pH and dissolved gas composition. The corrosion products were characterized by Raman spectroscopy, SEM and X-rays diffraction. In-situ tests with the Raman spectrometer were carried out to monitor the corrosion products evolution with time. (authors)

Lanarde, Lise [Gaz de France Research and Development Division, 361 avenue du President Wilson, BP33, 93211 Saint Denis La Plaine (France)]|[UPR15 du CNRS, Laboratoire des Interfaces et Systemes Electrochimiques, Universite Pierre et Marie Curie, C.P. 133, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Campaignolle, Xavier; Karcher, Sebastien; Meyer, Michel [Gaz de France Research and Development Division, 361 avenue du President Wilson, BP33, 93211 Saint Denis La Plaine (France); Joiret, Suzanne [UPR15 du CNRS, Laboratoire des Interfaces et Systemes Electrochimiques, Universite Pierre et Marie Curie, C.P. 133, 4 Place Jussieu 75252 Paris Cedex 05 (France)

2004-07-01

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The corrosion and protection of less carbon containing steel in subsoil  

International Nuclear Information System (INIS)

Full text: The protection and corrosion resistance of steel in subsoil waters of Baku subway were investigated. Kinetic curves were drawn. The results obtained from the experiment coincide with calculated results. There have been revealed and proposed hudron and fuel oil mixture protecting steel from corrosion in subsoil waters (97.8%) for the internal surface of steel pipes

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Spectroscopic identification of protective and non-protective corrosion coatings on steel structures in marine environments  

International Nuclear Information System (INIS)

Corrosion research, and the need to fully understand the effects that environmental conditions have on the performance of structural steels, is one area in which Moessbauer spectroscopy has become a required analytical technique. This is in part due to the need to identify and quantify the nanophase iron oxides that form on and protect certain structural steels, and that are nearly transparent to most other spectroscopic techniques. In conjunction with X-ray diffraction and micro-Raman analyses, the iron oxides that form the rusts on steels corroded in different marine and other environments can be completely identified and mapped within the rust coating. The spectroscopic analyses can be used to determine the nature of the environment in which structural steels have been, and these act as a monitor of the corrosion itself. Moessbauer spectroscopy is playing an important role in a new corrosion program in the United States and Japan in which steel bridges, old and new, are being evaluated for corrosion problems that may reduce their serviceable lifetimes. Moessbauer spectroscopy has been used to characterize the corrosion products that form the protective patina on weathering steel, as well those that form in adverse environments in which the oxide coating is not adherent or protective to the steel. Moessbauer spectroscopy has also become an important analytical technique for investigating the corrosion products that have formed on archaeological artifacts, and it is ed on archaeological artifacts, and it is providing guidance to aid in the removal of the oxides necessary for their conservation

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Preparation of ?-Mercaptopropyltrimethoxysilane's Films to Protect Steel Against Corrosion  

Science.gov (United States)

Traditionally, chromates and phosphates were used as pretreatments for metals to protect them from corrosion during a temporary period. Nowadays, due to their toxicity, replacements are being study. The most studied compounds are based on silanes and, among them, glicidoxypropyltrimethoxysilane, aminopropyltrimethoxysilane, and mercaptopropyltrimethoxysilane are the most important ones. The objective of this research work was to study the anticorrosive protection afforded by films of ?-mercaptopropyltrimethoxysilane deposited on SAE 1010 steel in order to select the optimum preparation conditions. The films were applied on sandblasted steel after 24 or 48 h of hydrolysis of the silane in a water/methanol solution (1.5/1, by volume) and cured for 10 min at 80 °C or for 1 h at 100 °C. In order to evaluate the characteristics of the films, Fourier transformed infrared spectroscopy was done on the films and the coated surfaces were observed by scanning electron microscopy. The anticorrosive protection afforded by the films was studied by electrochemical tests employing polarization curves (Tafel mode) in 0.5 M NaCl solution and corrosion potential measurements in NaCl 0.05 M. The best results were obtained with silane hydrolyzed for 48 h cured at 80 °C for 10 min.

Deyá, Cecilia

2015-03-01

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Corrosion protection mechanism of polyaniline blended organic coating on steel  

Energy Technology Data Exchange (ETDEWEB)

Epoxy-coal tar coatings are widely used to protect steel structures exposed to marine atmosphere due to their good barrier property. However, the presence of micropores and microcracks formed during the coating formation leads to failure of the coating due to permeation of corrosive ions. In recent years, it has been established that the coatings containing polyaniline (PANI) is able to protect pinholes and defects due to its passivating ability. Hence, a study has been made on the effect of polyaniline content (1 and 3%) in epoxy-coal tar coating on the corrosion protection of steel in 3% NaCl solution by electrochemical impedance spectroscopy (EIS) studies. Both phosphate- and chloride-doped polyanilines were prepared by a chemical oxidative polymerization method. From EIS studies, it has been found that the resistance value of the coatings containing 1 and 3% phosphate-doped polyaniline and 3% chloride-doped polyaniline pigmented coatings are similar to 10{sup 9} {Omega} cm{sup 2} even after 90 days exposure to NaCl solution, which are two orders high in comparison to that of conventional coal tar epoxy coatings. Besides, the conducting state of polyaniline has been found to be decreased after exposure to NaCl solution due to redox property of PANI. X-ray photoelectron spectroscopy studies have shown that polyaniline forms a complex layer with iron beneath the coating along with iron oxide.

Sathiyanarayanan, S.; Jeyaram, R.; Muthukrishnan, S.; Venkatachari, G. [Central Electrochemical Research Institute, Karaikkudi (India)

2009-07-01

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Corrosion protection of steel in ammonia/water heat pumps  

Science.gov (United States)

Corrosion of steel surfaces in a heat pump is inhibited by adding a rare earth metal salt to the heat pump's ammonia/water working fluid. In preferred embodiments, the rare earth metal salt includes cerium, and the steel surfaces are cerated to enhance the corrosion-inhibiting effects.

Mansfeld, Florian B.; Sun, Zhaoli

2003-10-14

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Studies and research work on the reinforcement steel and concrete surface corrosion protection methods  

Directory of Open Access Journals (Sweden)

Full Text Available Methods for reinforcement steel corrosion protection and concrete surface protection are analyzed. Knowing the corrosion process mechanism reinforcement steel can be protected by different protection methods even in the presence of crevices larger than those anticipated by design. The selection of the corrosion protection method depends on the reduction level of the reinforcement steel corrosion which in its turn is determined by the atmospheric conditions. The selection of the accelerated corrosion test conditions was made revealing the mechanism of the processes that take place at the steel reinforcement surface under natural weathering conditions. Crevices ranging from 0.05mm to 1.00mm or larger were opened by bending reinforced concrete girders on special equipment and were maintained all over the period of the corrosion resistance study.

Gheorghe Croitoru

2013-06-01

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Silicone coating systems to improve corrosion protection of steel  

International Nuclear Information System (INIS)

Due to German policy an interim storage of radioactive waste during additional 30 years is needed. This requires a high standard of storage containers especially in terms of corrosion resistance. Silicon elastomers (polysiloxanes) have favourable physical and chemical properties and seem to be appropriate for either outer or inner coating of storage containers. In this paper corrosion protection of different silicon coating systems has been investigated. The addition-curing polysiloxane RT622 (Wacker Chemie) was used for experiments. This is a low-viscosity material that could be modified by corrosion protecting pigments like zinc powder and micaceous iron ore. The pigment coatings assured better corrosion protection than unmodified silicon covering. Furthermore, the zinc powder caused the most notable improvement of corrosion protection. The best coating system consisted of a zinc paint and a polysiloxane coating. (orig.)

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Microbial Iron Respiration Can Protect Steel from Corrosion  

OpenAIRE

Microbiologically influenced corrosion (MC) of steel has been attributed to the activity of biofilms that include anaerobic microorganisms such as iron-respiring bacteria, yet the mechanisms by which these organisms influence corrosion have been unclear. To study this process, we generated mutants of the iron-respiring bacterium Shewanella oneidensis strain MR-1 that were defective in biofilm formation and/or iron reduction. Electrochemical impedance spectroscopy was used to determine changes...

Dubiel, M.; Hsu, C. H.; Chien, C. C.; Mansfeld, F.; Newman, D. K.

2002-01-01

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Protection of steel from carbon dioxide corrosion with volatile inhibitors. I. Liquid phase  

International Nuclear Information System (INIS)

It is shown that many known inhibitors of the steel atmospheric and hydrosulfide corrosion in the electrolytes, containing CO2, are inefficient. The new inhibitors IFKhAN-72 and IFKhAN-74 with high passivation capacity are efficient ones. The IFKhAN-72 inhibitor exceeds by its protective properties the best of the studied inhibitors of the amines-type- the amines A. Through delaying both electrode reactions suppresses the steel corrosion within the wide temperature range. It manifests thereby prolonged aftereffect and due to its high penetrating capacity it protects also the steel covered with the corrosion products

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Corrosion protection of carbon steel by an epoxy resin containing organically modified clay  

OpenAIRE

This study focusses on the use of montmorillonite clay (MMT) treated with an organic compound (aminotrimethylphosphonic acid (ATMP)) and dispersed in an epoxy resin to improve corrosion protection of carbon steel. X-ray diffraction was performed to verify that the individual silicate layers were separated and dispersed in the epoxy resin. Corrosion resistance of the coated steel was evaluated by electrochemical impedance spectroscopy (EIS) and local electrochemical impedance spectroscopy (LEI...

Hang, To Thi Xuan; Truc, Trinh Anh; Nam, Truong Hoai; Oanh, Vu Ke; Jorcin, Jean-baptiste; Pe?be?re, Nadine

2007-01-01

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Application of Self Assembled 6-aminohexanol layers for corrosion protection of 304 stainless steel surface  

International Nuclear Information System (INIS)

Grafting of 6-aminohexanol onto a 304 stainless steel substrate was performed with the assistance of polydopamine self assembly. The surface structure of the films was characterized using optical and scanning electron microscopy and X-ray energy dispersive spectroscopy confirmed the establishment of organic films. The corrosion resistance properties were characterized using the electrochemical impedance spectroscopy and potentiodynamic polarization curve measurements. Enhanced corrosion resistance performance was mainly ascribed to the compact film structure and the blocking characteristics against electron transfer of the modified 304 stainless steel substrate. - Highlights: ? Organic layers for corrosion protection of 304 stainless steel (SS) surface. ? Bio-inspired self assembly of polydopamine/composite films. ? 6-aminohexanol membrane synthesized on polydopamine modified SS surface. ? An efficiency route for improving corrosion protection.

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Marine corrosion protective coatings of hexagonal boron nitride thin films on stainless steel.  

Science.gov (United States)

Recently, two-dimensional, layered materials such as graphene and hexagonal boron nitride (h-BN) have been identified as interesting materials for a range of applications. Here, we demonstrate the corrosion prevention applications of h-BN in marine coatings. The performance of h-BN/polymer hybrid coatings, applied on stainless steel, were evaluated using electrochemical techniques in simulated seawater media [marine media]. h-BN/polymer coating shows an efficient corrosion protection with a low corrosion current density of 5.14 × 10(-8) A/cm(2) and corrosion rate of 1.19 × 10(-3) mm/year and it is attributed to the hydrofobic, inert and dielectric nature of boron nitride. The results indicated that the stainless steel with coatings exhibited improved corrosion resistance. Electrochemical impedance spectroscopy and potentiodynamic analysis were used to propose a mechanism for the increased corrosion resistance of h-BN coatings. PMID:23618222

Husain, Esam; Narayanan, Tharangattu N; Taha-Tijerina, Jose Jaime; Vinod, Soumya; Vajtai, Robert; Ajayan, Pulickel M

2013-05-22

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Evaluation of the effectiveness of selected corrosion inhibitors for protection of prestressing steels in PCPVs  

International Nuclear Information System (INIS)

The corrosion protection provided prestressing steel by portland cement-based grout in the presence of sulfide, nitrate, and chloride ion environments was evaluated. Results were compared to those obtained from selected, commercially available petroleum-microcrystalline waxes (petrolatums) compounded with organic corrosion inhibitors. The investigation was conducted in two phases: (1) a review of literature to establish the mechanisms of prestressing steel corrosion, techniques available for protection of prestressing steel in hostile environments, and the performance of structures that have utilized either nongrouted- or grouted-tendon prestressing systems; and (2) a laboratory study to develop relative performance data for portland cement grout and selected commercial petroleum-based greases and waxes containing inhibitors. Conclusions derived from the investigation indicate that (1) sulfide, nitrate, and chloride salts must be excluded from prestressing materials; (2) prestressing materials must be continuously protected from inimical environments; (3) the effectiveness of the protection provided by both the organic- and cement-based corrosion inhibitors is reduced unless the steel is completely covered; and (4) both cement- and organic-based corrosion inhibitors completely protect prestressing materials when properly applied

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Evaluation of the effectiveness of selected corrosion inhibitors for protection of prestressing steels in PCPVs  

Energy Technology Data Exchange (ETDEWEB)

The corrosion protection provided prestressing steel by portland cement-based grout in the presence of sulfide, nitrate, and chloride ion environments was evaluated. Results were compared to those obtained from selected, commercially available petroleum-microcrystalline waxes (petrolatums) compounded with organic corrosion inhibitors. The investigation was conducted in two phases: (1) a review of literature to establish the mechanisms of prestressing steel corrosion, techniques available for protection of prestressing steel in hostile environments, and the performance of structures that have utilized either nongrouted- or grouted-tendon prestressing systems; and (2) a laboratory study to develop relative performance data for portland cement grout and selected commercial petroleum-based greases and waxes containing inhibitors. Conclusions derived from the investigation indicate that (1) sulfide, nitrate, and chloride salts must be excluded from prestressing materials; (2) prestressing materials must be continuously protected from inimical environments; (3) the effectiveness of the protection provided by both the organic- and cement-based corrosion inhibitors is reduced unless the steel is completely covered; and (4) both cement- and organic-based corrosion inhibitors completely protect prestressing materials when properly applied.

Naus, D J

1979-03-01

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

Science.gov (United States)

The losses caused by the effect of the corrosion are of the order of 2-3,5% of the GDP of the developed countries or developing only in direct costs, losses in structures or products. This figure doubles by the indirect costs, losses of productivity or demands for delays. Beside the possible losses of human lives, any intent leaded to the decrease of the corrosion in rusty metals is a commendable objective from the point of view of the protection of the environment. Building industry employing reinforced concrete is able to project some structural elements (pillars, wrought, beam, etc.) in principle free of corrosion, assuring during many years the useful life of the work in service. However, the reinforced concrete would be' a perfect solution if the indefinite permanency of the passive state of the steel could be guaranteed. Indeed, although the steel is protected against corrosion due to basic pH which provides the cement, the severe action of saline media or the effect of CO2 can diminish this protection conditions beginning the corrosion in steel elements. Type-p doped conducting polymers, as polypyrrole, are firm candidates to protect carbon steel providing galvanic protection by stabilising the passive layer of Fe oxides initially grown. Doping the polymeric matrix with polioxometalates, concretely phosphotungstate PW12O403-, is a very interesting hypothesis due to their oxidising effect, improving the anodic protection by the hybrid material electrosynthesised on carbon steel substrate. First in the present work, a new method was developed by cyclic voltammetry in LiClO4 + acetonitrile medium in order to diminish the unavoidable oxidation of carbon steel when the electrosyntesis of the hybrid material polypyrrole/PW12O403- is carrying out. The beginning potential of polypyrrole polymerisation is about 0.8 V (vs. Ag/AgCl), a positive potential where oxidation of Fe substrate is high, not allowing the electrodeposition of the hybrid material. On the other hand, this pretreatment should guarantee appropriate conditions in order to obtain a coating with high adhesion on carbon steel. Once studied the better parameters for the synthesis of the hybrid material by cyclic voltammetry, hybrid material is morphological, chemical and electrochemical characterised by the following techniques: Cyclic Voltammetry, Scanning Electron Microscopy, Energy Dispersive X Ray, X Ray Photoelectron Spectroscopy and Electrochemical Impedance Spectroscopy. The hybrid material polypyrrole/PW 12O403-. chemical structure presents Fe oxides and hydroxide within the polypyrrole polycationic matrix. Hybrid material polypyrrol/PW12O403- diminishes the corrosion of carbon steel in NaOH and Porland cement filtering solutions. These cement solutions simulate the pore fluid conditions existing in cured mortar or concrete elements. Fe ion concentration data were determinated in corrosion tests. Voltammetric response of polymeric coatings was evaluated by cyclic voltammetry. Finally, the protection provided by hybrid material polypyrrole/PW 12O403, in oxidised and reduced state, was evaluated on carbon steel electrodes embedded in Portland cement mortars immersed in seawater and submitted to an accelerated carbonation process for 265 days. Polymeric material covered carbon steel electrodes in reduced state suffer a Fe gravimetric loss 15 times lower than the ones of bare electrodes against chlorides attack, due to the effect of physical barrier. Hybrid material covered electrodes in oxidised state after being submitted to a carbonation process suffer a Fe gravimetric loss 2.5 times lower than the ones of bare electrodes, due to galvanic protection provided by hybrid material polypyrrole/PW 12O403- on carbon steel.

Bonastre Cano, Jose Antonio

25

The Effect of Oil on Carbon Dioxide Corrosion Inhibition on Carbon Steel - Potential for Improved Corrosion Protection  

OpenAIRE

The search for robust and cost efficient ways to prevent internal corrosion of carbon steel piping and equipment in oil and gas production and transportation has lead to the development of highly sophisticated CO2 corrosion inhibitor products. This thesis studies oil wetting and corrosion inhibitor performance on bare steel and steel with corrosion product deposits on the surface, in the presence of a refined, low aromatic hydrocarbon oil. Three surfactants were used in...

Foss, Martin Smedstad

2010-01-01

26

Evaluation of the protection behaviour of reinforcement steel against corrosion induced by chlorides in reinforced mortar specimens  

International Nuclear Information System (INIS)

In this work various treatments for protecting reinforcing steels against corrosion induced by chlorides have been evaluated. Additives to mortars and surface treatments given to reinforcing steels were evaluated as corrosion protection measures. In the preliminary tests the corrosion resistance of a CA 50 steel treated by immersion in nearly 50 different solutions, was determined. The solutions were prepared with tannins (from various sources) and/or benzotriazole, and during immersion, a surface film formed on the steel. The corrosion resistance of the coated steels was evaluated in a saturated Ca(OH)2 solution with 5% (wt) NaCl. Preliminary tests were also carried out with mortars reinforced with uncoated steel to which tannin or lignin was added. Two organic coatings, a monocomponent and a bicomponent type, formulated specially for this investigation, with both tannin and benzotriazole, were also tested in the preliminary tests to select the coating with better corrosion protection property. The bicomponent type (epoxy coating) showed better performance than the monocomponent type coating, and the former was therefore chosen to investigate the corrosion performance on CA 50 steel inside mortar specimens. From the preliminary tests, two solutions with tannin from two sources, Black Wattle (Acacia mearnsii) and Brazilian tea (Ilex paraguariensis St. Hill), to which benzotriazole and phosphoric acid were added, were chosen. Mortar specimens reinforced with CA50 steel treated by immersion in these two solutions were prepared. Also, epoxy coated CA50 steel was tested as reinforcement inside mortar specimens. Mortars reinforced with uncoated CA50 steel were also prepared and corrosion tested for comparison. The effect of tannin and lignin as separate additives to the mortar on the corrosion resistance of uncoated steel was also studied. The reinforced mortar specimens were tested with various cycles of immersion for 2 days in 3.5% (wt) NaCl followed by with air drying for 5 days. The corrosion tests used in this investigation were gravimetric and electrochemical tests. The results showed satisfactory corrosion performance for all kinds of protection measures. However, the performance depended on the type of protection used. The best performance was obtained with tannin containing epoxy coated steel, followed by the steel treated by immersion in tannin containing solutions and finally by the addition of tannin (Black Wattle) or lignin to the mortar. All the protection measures evaluated in this study are economically viable and environmentally friendly and can therefore be considered for protecting reinforcement steels against corrosion. (author)

27

Aluminium electroplated from ionic liquids as protective coating against steel corrosion  

International Nuclear Information System (INIS)

The protective action of thin layers of aluminium electroplated on a carbon steel (UNI Fe360B) has been studied. The coatings were obtained via electroreduction, at room temperature, from an ionic liquid constituted by 1-butyl-3-methyl-imidazolium heptachloroaluminate. Coatings of different thickness, ranging from 10 to 40 ?m, were obtained. Their morphology and chemical composition were investigated using SEM microscopy coupled with EDX microanalysis and X-ray diffraction. Electrochemical tests (potentiodynamic polarization curves, open-circuit potential and electrochemical impedance spectroscopy) were performed in order to characterise the corrosion resistance of the coating in 3.5% NaCl aqueous solution. Visual investigation of the samples during long term of exposition to neutral salt spray gave an evaluation of their free corrosion properties. It was found that the aluminium layers deposited from ionic liquids significantly protect the substrate from the general corrosion and this action increases with the coating thickness

28

Comparative Study on Corrosion Protection of Reinforcing Steel by Using Amino Alcohol and Lithium Nitrite Inhibitors  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, the ability of lithium nitrite and amino alcohol inhibitors to provide corrosion protection to reinforcing steel was investigated. Two types of specimens—reinforcing steel and a reinforced concrete prism that were exposed to chloride ion levels resembling the chloride attack environment—were prepared. An autoclave accelerated corrosion test was then conducted. The variables tested included the chloride-ion concentration and molar ratios of anti-corrosion ingredients in a CaOH2-saturated aqueous solution that simulated a cement-pore solution. A concentration of 25% was used for the lithium nitrite inhibitor LiNO2, and an 80% solution of dimethyl ethanolamine ((CH32NCH2CH2OH, hereinafter DMEA was used for the amino alcohol inhibitor. The test results indicated that the lithium nitrite inhibitor displayed anti-corrosion properties at a molar ratio of inhibitor of ?0.6; the amino alcohol inhibitor also displayed anti-corrosion properties at molar ratios of inhibitor greater than approximately 0.3.

Han-Seung Lee

2015-01-01

29

The study of the corrosion protection of the low-carbon steel using film-products  

International Nuclear Information System (INIS)

The paper reports studies on the efficiency of the film-inhibitors that covered low-carbon steel placed in a humid medium, and also, the optimization of the working conditions to improve the resistance to corrosion. The analyzes were done in the Industrial Physical - Chemical Laboratories of INSA - Lyon by electrochemical stationary techniques. The experimental device was a potentiometer of type EGG PAR (Princeton Applied Research). It was connected with a computer and three potential electrodes introduced in a cell with NaCl 30 g/l solution to acquire the data and to process the information. The film-products used were organic hydrosoluble polymers with diphosphonic 'heads' that permit a very good absorption at the metallic surface. This research is used to protect the installations of low-carbon steel against the atmospheric and high temperature corrosion. (authors)

30

Interaction of Benzimidazoles and Benzotriazole: Its Corrosion Protection Properties on Mild Steel in Hydrochloric Acid  

Science.gov (United States)

Synergistic hydrogen-bonded interaction of alkyl benzimidazoles and 1,2,3-benzotrizole and its corrosion protection properties on mild steel in hydrochloric acid at different temperatures have been studied using polarization, EIS, adsorption, surface studies, and computational methods. The extent of synergistic interaction increases with temperature. Quantum chemical approach is used to calculate some electronic properties of the molecules and to ascertain the synergistic interaction, inhibitive effect, and molecular structures. The corrosion inhibition efficiencies and the global chemical reactivity relate to some parameters, such as total energy, E HOMO, E LUMO, and gap energy (? E). 1,2,3-Benzotrizole interacts with benzimidazoles derivatives up to a bond length of approximately 1.99 Å. This interaction represents the formation of a hydrogen bond between the 1,2,3-benzotrizole and benzimidazoles. This synergistic interaction of 1,2,3-benzotrizole and benzimidazole derivatives offers extended inhibition efficiency toward mild steel in hydrochloric acid.

Ramya, K.; Mohan, Revathi; Joseph, Abraham

2014-11-01

31

Characterization of organic-inorganic hybrid coatings for corrosion protection of galvanized steel and electroplated ZnFe steel  

Scientific Electronic Library Online (English)

Full Text Available The development of hybrids materials has been extensively investigated in recent years. The combination of a wide variety of compositions and production processes had permitted the use of these materials in different applications like coatings for corrosion protection of metals. In this work organic [...] -inorganic hybrid materials have been prepared from the hydrolysis of tetraethylorthosilicate and silanol-terminated polidymetilmetoxysilane using a sol-gel process. These materials have been applied on galvanized steel and on steel electroplated with a ZnFe. In order to evaluate the degradation behavior of these coatings, electrochemical techniques (Electrochemical Impedance Spectroscopy and Potentiodynamic Polarization) were used. EIS data was fitted to an equivalent circuit from which the electrochemical parameters were obtained. Results show a good protective character of the hybrid films, when compared with uncovered specimens. The overall performance of the coating systems appears to be highly dependent on the kind of metallic coating applied to the steel.

Maria Eliziane Pires de, Souza; Edith, Ariza; Margarita, Ballester; Inez Valéria Pagotto, Yoshida; Luis Augusto, Rocha; Célia Marina de Alvarenga, Freire.

2006-03-01

32

Characterization of organic-inorganic hybrid coatings for corrosion protection of galvanized steel and electroplated ZnFe steel  

Directory of Open Access Journals (Sweden)

Full Text Available The development of hybrids materials has been extensively investigated in recent years. The combination of a wide variety of compositions and production processes had permitted the use of these materials in different applications like coatings for corrosion protection of metals. In this work organic-inorganic hybrid materials have been prepared from the hydrolysis of tetraethylorthosilicate and silanol-terminated polidymetilmetoxysilane using a sol-gel process. These materials have been applied on galvanized steel and on steel electroplated with a ZnFe. In order to evaluate the degradation behavior of these coatings, electrochemical techniques (Electrochemical Impedance Spectroscopy and Potentiodynamic Polarization were used. EIS data was fitted to an equivalent circuit from which the electrochemical parameters were obtained. Results show a good protective character of the hybrid films, when compared with uncovered specimens. The overall performance of the coating systems appears to be highly dependent on the kind of metallic coating applied to the steel.

Maria Eliziane Pires de Souza

2006-03-01

33

Protective properties of zinc-containing oil-based coatings against steel atmospheric corrosion  

Energy Technology Data Exchange (ETDEWEB)

The protective efficiency of the compositions of zinc powder and fresh and waste oils has been studied with respect to the atmospheric corrosion of carbonaceous steel (St3). The oil compositions contained 25-75 wt.% of zinc powder. Waste motor oil (WMO), filtered fraction of WMO (FWMO), waste and fresh industrial I-20A oils have been used as a solvent-support. The influence of zinc concentration in the oil compositions on the thickness of the oil based coatings and the inhibitor effect in 3% NaCl solution, in the apparatus for heat and moisture treatment and in an open site has been investigated. The coatings on base of WMO and FWMO and 75% concentration of Zn powder show the highest protective action. Kinetics of the partial electrode reactions on steel in conditions of a presence of the protective coatings and water mass transfer through the oil composition films has been studied. (authors)

Tsygankova, L. E.; Shel, N.V.; Paramonov, S.Yu.; Vigdorovich, V. I. [Derzhavin State University 33, Internatsionalnaya St., Tambov, 392622 (Russian Federation)

2004-07-01

34

Electrochemical determination of the minimum cathodic protection potential and underground steel corrosion rate. On the moderate criteria for the protection efficiency  

International Nuclear Information System (INIS)

Experimentally are determined the minimum protection potential Emin and steel corrosion rate in a number of soils by means of calculation using the cathode polarization curve. Their correlation is shown with results of weight tests in conditions of the free corrosion and cathode polarization. It is shown too that Emin is not connected directly with the steel free corrosion rate but when lowering Emin normally is decreased. Using Emin as a characteristic for the soil corrosion effect and features of the cathode protection when softening the criteria of its efficiency are discussed. 21 refs., 4 figs., 2 tabs

35

Organic-inorganic hybrid coatings for corrosion protection of galvanized steel and electroplated znfe steel  

OpenAIRE

The development of hybrids materials by the sol-gel process has been extensively investigated in recent years. The combination a wide variety of compositions and production processes had permit the use of these materials in different applications like coatings for corrosion protection of metals and abrasion resistant coatings. In this work organic-inorganic hybrid materials have been prepared from the hydrolysis of tetraethylorthosilicate (TEOS) and silanol-terminated polidymet...

Souza, M. E. P.; Ariza, E.; Ballester, M.; Yoshida, I. V. P.; Rocha, L. A.; Freire, C. M. A.

2004-01-01

36

Corrosion protection performance of porous strontium hydroxyapatite coating on polypyrrole coated 316L stainless steel.  

Science.gov (United States)

Polypyrrole/strontium hydroxyapatite bilayer coatings were achieved on 316L stainless steel (316L SS) by the electropolymerisation of pyrrole from sodium salicylate solution followed by the electrodeposition of porous strontium hydroxyapatite. The formation and the morphology of the bilayer coatings were characterised by Fourier transform infrared spectroscopy (FT-IR) and high resolution scanning electron microscopy (HRSEM), respectively. The corrosion resistance of the coated 316L SS specimens was investigated in Ringer's solution by electrochemical techniques and the results were substantiated with inductively coupled plasma atomic emission spectrometry (ICP-AES). The passive film underneath the polypyrrole layer is effective in protecting 316L SS against corrosion in Ringer's solution. Moreover, we believe that the top porous strontium hydroxyapatite layer can provide potential bioactivity to the 316L SS. PMID:23475060

Gopi, D; Ramya, S; Rajeswari, D; Kavitha, L

2013-07-01

37

Use of Extracted Green Inhibitors as a Friendly Choice in Corrosion Protection of Low Alloy Carbon Steel  

Directory of Open Access Journals (Sweden)

Full Text Available Mitigation of corrosion impact on environment is an important step in environmental protection. Use of environmentally friendly corrosion protection methods is very important. It is smart to choose cheap and safe to handle compounds as corrosion inhibitors. The use of green inhibitors (extracted inexpensively, from the seed endosperm of some Leguminosae plants, and investigation of their efficiency in corrosion protection is the aim of this study. As green inhibitor one kind of polysaccharides (galactomannan from locust bean gum (also known as carob gum, carob bean gum extracted from the seed of carob tree is used. Corrosion protection efficiency of these extracted green inhibitors was tested for carbon steel marked as: steel 39, steel 44, and iron B 500 (usually applied as reinforcing bars to concrete. Sulfuric acid solution in the presence of chloride ions was used as corrosion media. The composition of corrosion acid media used was 1 mol L-1 H2SO4 and 10-3 mol L-1 Cl- (in the form of NaCl. Electrochemical techniques such as potentiodynamic polarization methods were used for inhibitor efficiency testing.

Jano, A.

2012-11-01

38

Corrosion protection of low-carbon steel using exopolysaccharide coatings from Leuconostoc mesenteroides  

Science.gov (United States)

Corrosion is one of the most serious and challenging problems faced worldwide by industry. This research investigates the inhibition of corrosive behavior of SAE1010 steel by bacterial exopolysaccharides. Electrochemical Impedance Spectroscopy was used to evaluate the corrosion inhibition of diffe...

39

Thermodynamic aspects of the development of inhibitory methods of protecting steel from corrosion in salt water environments  

Directory of Open Access Journals (Sweden)

Full Text Available  The thermodynamics aspects of steel in water-salt solutions spontaneous corrosion and ways of purposeful creation of inhibition methods for its slow-down were considered. For the system Fe-H2O on the basis of diagram Pourbe analysis were determined definite ranges of potentials of metal and pH of the solutions for which corrosive destruction speed reduction were achieved. It is shown that the effective corrosion protection of steel can be achieved by means of measures which include application of inhibitors with simultaneous medium pH modification, as a result there takes place a transition of metal into a stable passivated state. Potentiostatic research of steel in water-salt solutions corrosion had confirmed efficiency of the method offered.

?.?. ??????????

2008-04-01

40

On the protective effect of KhOSP-10 inhibitor during corrosion, hydrogenadsorption and corrosion cracking of a steel in sulfuric acid  

International Nuclear Information System (INIS)

The protective propeties of inhibitor KhOSP-10 in the time of corrosion and corrosive cracking of steel 40Kh are higher then those of inhibitors KPI-1, KI-1, I-I-V etc. Its ability to reduce steel hydrogenation is the same as in the case of KPI-1 inhibitor i.e. below that of KI-1. HCl additives enhance the efficiency of inhibitors KPI-1, KI-1, I-1-V etc. up to the protective ability of KhOSP-10. Kinetics of the electrode processes was estimated from polarization curves

41

Corrosion properties of steel protected by nanometre-thick oxide coatings  

International Nuclear Information System (INIS)

Highlights: • 40–50 nm mixed alumina–tantala coatings were grown by atomic layer deposition. • Effects of substrate surface finish and oxide mix were analysed. • Nanolaminate stacks are better resistant to breakdown. • Localised corrosion occurs at pre-existing coating defects exposing substrate sites. • Substrate brushing and H2–Ar plasma pre-treatment hinder pit initiation. - Abstract: A comprehensive study of the corrosion properties of low alloy steel protected by 40–50 nm aluminium and tantalum mixed oxide coatings grown by atomic layer deposition is reported. Electrochemical and surface analysis was performed to address the effect of substrate surface finish and whether an oxide mixture or nanolaminate was used. There was no dissolution or breakdown for nanolaminate alumina/tantala stacks in acidic NaCl solution. Localised corrosion (pitting) took place when defects exposing the substrate pre-existed in the coating. Substrate pre-treatment by brushing and H2–Ar plasma was instrumental to block or slow down pit initiation by reducing the defect dimensions

42

Corrosion Protection of Steel by Thin Coatings of Starch-oil Emulsions  

Science.gov (United States)

Corrosion of materials is one of the most serious and challenging problems faced worldwide by industry. This research investigated the inhibition of corrosive behavior by jet-cooked starch-soybean oil composites on SAE 1010 steel. Electrochemical Impedance Spectroscopy (EIS) was used to evaluate t...

43

Protection of type 316 austenitic stainless steel from intergranular stress corrosion cracking by thermo-mechanical treatment  

International Nuclear Information System (INIS)

Thermomechanical treatment that causes carbide stabilizing aging of cold worked material followed by recrystallization heating made standard stainless steels highly resistant to intergranular corrosion and stress corrosion cracking in different test environments. After a typical thermal history of simulated welding, several IGSCC susceptibility tests were made. The results showed that the treatment was successful in type 316 steel in wide range of conditions, while type 304 was protected only to a small extent even by closely controlled treatment. Response of the materials to the sensitizing heating in terms of impurity segregation at grain boundaries was also examined by means of microchemical analysis. Advantage of method is that no special care is required in selecting heats of material, so that conventional type 316 is usable by improving the mechanical properties substantially through the treatment. In some optimized cases the mechanical property improvement was typically recognized by the yield strength by about 20% higher at room temperature, compared with the material mill annealed. (author)

44

Corrosion of steel in concrete  

International Nuclear Information System (INIS)

A comparative study has been made of those properties of Massiv and Standard cements which are considered to determine their ability to protect steel reinforcement from corroding. Saturated Massiv cement has a higher evaporabel water content, but a significantly finer pore structure than has saturated Standard cement. This fine structure resulted in an electrical resistivity ten times higher and chloride diffusivity ten times lower than those of Standard cement. Electrochemical measurements have shown that the passive current density of steel in Massiv mortar is higher than that of steel in Standard mortar, but the higher current should lead to a more rapid decrease in potential to a level at which neither chloride attack of hydrogen evolution will occur. Whereas steel in Standard mortar was found to be highly susceptible to crevice corrosion, no such attack has been observed in Massiv mortar. Moreover, the initiation of chloride induced corrosion and the subsequent rates of corrosion were both lower in Massiv mortar than in Standard mortar. Thus, it may be predicted that Massiv cement would provide greater protection for steel reinforcement in underground structures exposed to chloride containing ground water than would Standard cement. (author)

45

Fabrication of continuous mesoporous organic-inorganic nanocomposite films for corrosion protection of stainless steel in PEM fuel cells  

International Nuclear Information System (INIS)

Graphical abstract: Ordered mesoporous organic-inorganic composite film has been achieved by sol-gel and spin-coating techniques. We believe that the mesoporous composite films have a potential application as a protect coating of bipolar plate material. Display Omitted Research highlights: ? Ordered mesoporous composite film was deposited on the 304 stainless steel. ? This composite film exhibited excellent protective performance in 0.5 M H2SO4. ? The film exhibited a high surface tension with water contact angle close to 90o. - Abstract: The organic-inorganic composite film was deposited on the 304 stainless steel as bipolar plate material for proton exchange membrane fuel cells by spin-coating method. As shown by XRD, N2 adsorption-desorption and TEM, the composite films exhibit ordered mesoporous structures. The corrosion tests in 0.5 M H2SO4 system displayed that, compared with 304SS, the composite films made corrosion potential shifted to positive direction by 250-1000 mV (SCE) and corrosion current decreased by 1-3 orders of magnitude. Wherein, the C-50-60% composite film showed the optimal protective performance, its corresponding potentiostatic polarization process was extremely stable in the simulated fuel cells environment.

46

Protection of carbon steel against hot corrosion using thermal spray Si- and Cr-base coatings  

Energy Technology Data Exchange (ETDEWEB)

A Fe75Si thermal spray coating was applied on the surface of a plain carbon steel baffle plate. Beneath this coating, a Ni20Cr coating was applied to give better adherence to the silicon coating. The baffle was installed in the high-temperature, fireside, corrosion zone of a steam generator. At the same time, an uncoated 304 stainless steel baffle was installed nearby for comparison. For 13 months the boiler burned heavy fuel oil with high contents of vanadium. The samples were studied employing scanning electron microscopy, x-ray microanalysis, and x-ray diffraction techniques. After that, it was possible to inspect the structural state of the components, and it was found that the stainless steel baffle plates were destroyed almost completely by corrosion, whereas the carbon steel coated baffle plate did not suffer a significant attack, showing that the performance of the thermal spray coating was outstanding and that the coating was not attacked by vanadium salts of the molten slag.

Porcayo-Calderon, J. [Inst. de Investigaciones Electricas, Cuernavaca (Mexico); Gonzalez-Rodriguez, J.G. [U.A.E.M., Cuernavaca (Mexico). Facultad de Ciencias Quimicas e Ingenieria; Martinez, L. [UNAM, Cuernavaca (Mexico). Inst. de Fisica

1998-02-01

47

Preparation of crosslinked amphiphilic silver nanogel as thin film corrosion protective layer for steel.  

Science.gov (United States)

Monodisperse silver nanoparticles were synthesized by a new developed method via reaction of AgNO3 and oleic acid with the addition of a trace amount of Fe3+ ions. Emulsion polymerization at room temperature was employed to prepare a core-shell silver nanoparticle with controllable particle size. N,N'-methylenebisacrylamide (MBA) and potassium peroxydisulfate (KPS) were used as a crosslinker, and as redox initiator system, respectively for crosslinking polymerization. The structure and morphology of the silver nanogels were characterized by Fourier transform infrared spectroscopy (FTIR), transmission and scanning electron microscopy (TEM and SEM). The effectiveness of the synthesized compounds as corrosion inhibitors for steel in 1 M HCl was investigated by various electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Monolayers of silver nanoparticle were self-assembled on the fresh active surface of the steel electrode and have been tested as a corrosion inhibitor for steel in 1 M HCl solution. The results of polarization measurements showed that nanogel particles act as a mixed type inhibitor. PMID:25036152

Atta, Ayman M; El-Mahdy, Gamal A; Al-Lohedan, Hamad A; Ezzat, Abdelrahman O

2014-01-01

48

Migrating corrosion inhibitor protection of concrete  

Energy Technology Data Exchange (ETDEWEB)

Migrating corrosion inhibitors (MCI) were developed to protect steel rebar from corrosion in concrete. They were designed to be incorporated as an admixture during concrete batching or used for surface impregnation of existing concrete structures. Two investigations are summarized. One studied the effectiveness of MCIs as a corrosion inhibitor for steel rebar when used as an admixture in fresh concrete mix. The other is a long-term study of MCI concrete impregnation that chronicles corrosion rates of rebar in concrete specimens. Based on data from each study, it was concluded that migrating corrosion inhibitors are compatible with concrete and effectively delay the onset of corrosion.

Bjegovic, D.; Miksic, B.

1999-11-01

49

Corrosion protection of 316 L stainless steel by a TiO2 nanoparticle coating prepared by sol-gel method  

International Nuclear Information System (INIS)

A uniform and TiO2 nanoparticle coating on steels has been prepared using sol-gel method and hydrothermal post-treatments. The morphology and structure of the coatings were analysed using atomic force microscopy and X-ray diffraction. The anticorrosion performances of the coatings in dark and under ultraviolet illumination have been evaluated by using electrochemical techniques. The influences of coating thickness, pH and NaCl concentration on corrosion protection have been examined as well. The results indicate that the TiO2 nanoparticle coatings on steels exhibit an excellent corrosion resistance due to a ceramic protective barrier on metal surface in dark, and a photo-generated cathodic protection current under UV illumination. The electrochemical impedance spectroscopy measurements provide an explanation to the increased resistance of nano TiO2 particles coated 316 L stainless steel against corrosion

50

Long term corrosion on T91 and AISI1 316L steel in flowing lead alloy and corrosion protection barrier development: Experiments and models  

International Nuclear Information System (INIS)

Considering the status of knowledge on corrosion and corrosion protection and especially the need for long term compatibility data of structural materials in HLM a set of experiments to generate reliable long term data was defined and performed. The long term corrosion behaviour of the two structural materials foreseen in ADS, 316L and T91, was investigated in the design relevant temperature field, i.e. from 300 to 550 deg. C. The operational window of the two steels in this temperature range was identified and all oxidation data were used to develop and validate the models of oxide scale growth in PbBi. A mechanistic model capable to predict the oxidation rate applying some experimentally fitted parameters has been developed. This model assumes parabolic oxidation and might be used for design and safety relevant investigations in future. Studies on corrosion barrier development allowed to define the required Al content for the formation of thin alumina scales in LBE. These results as well as future steps and required improvements are discussed. Variation of experimental conditions clearly showed that specific care has to be taken with respect to local flow conditions and oxygen concentrations.

51

Effect of zinc phosphate chemical conversion coating on corrosion behaviour of mild steel in alkaline medium: protection of rebars in reinforced concrete  

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Full Text Available We outline the ability of zinc phosphate coatings, obtained by chemical conversion, to protect mild steel rebars against localized corrosion, generated by chloride ions in alkaline media. The corrosion resistance of coated steel, in comparison with uncoated rebars and coated and uncoated steel rebars embedded in mortar, were evaluated by open-circuit potential, potentiodynamic polarization, cronoamperometry and electrochemical impedance spectroscopy. The coated surfaces were characterized by x-ray diffraction and scanning electron microscopy. First, coated mild steel rebars were studied in an alkaline solution with and without chloride simulating a concrete pore solution. The results showed that the slow dissolution of the coating generates hydroxyapatite Ca10(PO46(OH2. After a long immersion, the coating became dense and provided an effective corrosion resistance compared with the mild steel rebar. Secondly, the coated and uncoated steel rebars embedded in mortar and immersed in chloride solution showed no corrosion or deterioration of the coated steel. Corrosion rate is considerably lowered by this phosphate coating.

Florica Simescu and Hassane Idrissi

2008-01-01

52

Hybrid layers deposited by an atmospheric pressure plasma process for corrosion protection of galvanized steel.  

Science.gov (United States)

Finding alternative treatments to reproduce anticorrosion properties of chromated coatings is challenging since both physical barrier and self-healing effects are needed. Siloxane based treatments are known to be a promising way to achieve physical barrier coatings, mainly plasma polymerized hexamethyldisiloxane (ppHMDSO). In addition, it is known that cerium-based coatings can also provide corrosion protection of metals by means of self-healing effect. In this frame, innovative nanoAlCeO3/ppHMDSO layers have thus been deposited and studied. These combinations allow to afford a good physical barrier effect and active properties. Liquid siloxane and cerium-based particles mixture is atomized and introduced as precursors into a carrier gas. Gas mixture is then injected into an atmospheric pressure dielectric barrier discharge (DBD) where plasma polymerization of the siloxane precursor occurs. The influence of cerium concentration on the coating properties is investigated: coating structure and topography have been studied by scanning electron microscopy (SEM) and interferometry, and corrosion resistance of these different coatings is compared by electrochemistry techniques: polarization curves and electrochemical impedance spectroscopy (EIS). Potential self-healing property afforded by cerium in the layer was studied by associating EIS measurements and nanoscratch controlled damaging. Among the different combinations investigated, mixing of plasma polymerized HMDSO and AICeO3 nanoparticles seems to give promising results with a good physical barrier and interesting electroactive properties. Indeed, corrosion currents measured on such coatings are almost as low as those measured with the chromated film. Combination of nanoscratch damaging of layers with EIS experiments to investigate self-healing also allow to measure the active protection property of such layers. PMID:20355472

Del Frari, D; Bour, J; Bardon, J; Buchheit, O; Arnoult, C; Ruch, D

2010-04-01

53

High temperature corrosion protection of austenitic AISI 304 stainless steel by Si, Mo and Ce ion implantation  

Energy Technology Data Exchange (ETDEWEB)

The influence of implanted silicon, molybdenum and cerium on the oxidation behaviour of a 18Cr8Ni stainless steel was studied at 1173 K up to 144 h in air under isothermal conditions in order to verify the enhanced selective oxidation of chromium by these elements. The implanted surface and the corrosion products formed were characterized by means of AES, SEM, EDS and XRD. Implanted depth profiles were calculated by TRIM96 computational code. The implanted silicon and cerium markedly improved protection against oxidation of the alloy by enhanced chromium transport while molybdenum gave rise to an accelerated oxidation due to the formation of volatile MoO{sub 3} species. Further, ion implantation was found to play a beneficial effect against decarburization of the alloy. (orig.) 17 refs.

Perez, F.J.; Otero, E.; Hierro, M.P.; Gomez, C.; Pedraza, F. [Universidad Complutense de Madrid (Spain). Dept. de Ciencia de los Materiales; Segovia, J.L. de [Dept. de Fisica del Vacio, Consejo Superior de Investigaciones Cientificas, Inst. Torres Quevedo, Madrid (Spain); Roman, E. [Consejo Superior de Investigaciones Cientificas, Inst. de Ciencia de los Materiales, Canto Blanco-Madrid (Spain)

1998-10-10

54

Corrosion of carbon steel in neutral water  

International Nuclear Information System (INIS)

The initial corrosion behavior of materials used in the construction of heat exchanger and piping system of BWR nuclear power plants and thermal power plants have been examined in neutral water at 30, 50, 100, 160, 200, and 285 deg C with two concentrations of dissolved oxygen in the water. In air-saturated water, the corrosion rate of carbon steel was so higher than those in deaerated conditions and the maximum corrosion rate was observed at 200 deg C. The corrosion rate in deaerated water gradually increased with increasing the water temperature. Low alloy steel (2.25 Cr, 1Mo) exhibited good corrosion resistance compared with the corrosion of carbon steel under similar testing conditions. Oxide films grown on carbon steel in deaerated water at 50, 100, 160, 200, and 285 deg C for 48 and 240 hrs were attacked by dissolved oxygen in room temperature water respectively. However the oxide films formed higher than about 160 deg C showed more protective. The electrochemical behavior of carbon steel with oxide films was also similar to the effect of temperature on the stability of oxide films. (author)

55

Corrosion and cathodic protection at disbonded coatings  

Energy Technology Data Exchange (ETDEWEB)

The effectiveness of cathodic protection to control corrosion and the resulting corrosion rate of pipelines are determined by the chemical and electrochemical conditions at local areas along the pipeline. The disbonding of coatings and tapes is also controlled to a large extent by the chemical and electrochemical conditions. Processes that occur on the metal surface and their effect on corrosion and cathodic protection are discussed with respect to real pipeline conditions. Disbonded coatings on steel can interfere with the current distribution from cathodic protection. Shielding the current under disbonded coatings can affect the level of protection, the corrosion behavior and the disbonding of coatings. A major thrust in the laboratories has been the use of laboratory measurements and computational models to determine the changes in the corrosive environment that occur beneath disbonded coatings as a function of applied potential, disbonded area geometry, prior corrosion products and wet/dry cycles. These results are summarized here.

Payer, J.H.; Fink, K.M.; Perdomo, J.J.; Rodriguez, R.E.; Song, I.; Trautman, B. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science and Engineering

1996-12-31

56

Corrosion protection of steel by thin coatings of starch-oil dry lubricants  

Science.gov (United States)

Corrosion of materials is one of the most serious and challenging problems faced worldwide by industry. Dry lubricants reduce friction between two metal surfaces. This research investigated the inhibition of corrosive behavior a dry lubricant formulation consisting of jet-cooked corn starch and soyb...

57

Development of Nb2O5|Cu composite as AISI 1020 steel thermal spray coating for protection against corrosion by soil in buried structures  

International Nuclear Information System (INIS)

An Nb2O|Cu corrosion-resistant coating was developed and applied onto AISI 1020 steel substrate by Powder Flame Spray. A galvanostatic electrochemical technique was employed, with and without ohmic drop, in four different soils (two corrosively aggressive and two less aggressive). Behavior of coatings in different soils was compared using a cathodic hydrogen reduction reaction (equilibrium potential, overvoltage and exchange current density) focusing on the effect of ohmic drop. Results allow recommendation of Nb2O5|Cu composite for use in buried structure protection. (author)

58

Corrosion characteristics of DMR-1700 steel and comparison with different steels in marine environment  

International Nuclear Information System (INIS)

In the present paper, a systematic corrosion study has been carried out on DMR-1700 steel to understand the protective nature of oxide scale that forms on its surface under marine environmental conditions. Further, the studies related to oxide scales as well as pitting and crevice corrosion resistance of both stainless steels and widely used low alloy steel EN24 in marine environment have been studied for comparison purpose. The surface morphologies of corroded steels have been observed under scanning electron microscope (SEM) in order to understand the nature of corrosion. A high performance protective coating that has been developed for protection of low alloy steels DMR-1700 and EN24 against corrosion is presented after stressing the importance of surface engineering in enhancing the life of steels. Based on the studies with different techniques, DMR-1700 steel has been recommended for manufacture of components used in aerospace systems in association with appropriate protective coating for improving their efficiency

59

Tantalum oxide nanocoatings prepared by atomic layer and filtered cathodic arc deposition for corrosion protection of steel: Comparative surface and electrochemical analysis  

International Nuclear Information System (INIS)

Highlights: ? 50 nm Ta2O5 coatings grown by ALD at 160 °C and FCAD for protection of steel. ? Combined analysis by ToF-SIMS, XPS, polarization curves and EIS. ? Relation between chemical architecture and corrosion protection properties studied. ? Localized corrosion by pitting with absence of coating dissolution demonstrated. ? Origin and role of spurious interfacial oxide promoting coating breakdown emphasized. -- Abstract: A comparative study by Time-of-Flight Secondary Ions Mass Spectrometry and X-ray Photoelectron Spectroscopy, i–E polarization curves and Electrochemical Impedance Spectroscopy of the corrosion protection of low alloy steel by 50 nm thick tantalum oxide coatings prepared by low temperature Atomic Layer Deposition (ALD) and Filtered Cathodic Arc Deposition (FCAD) is reported. The data evidence the presence of a spurious oxide layer mostly consisting of iron grown by transient thermal oxidation at the ALD film/substrate interface in the initial stages of deposition and its suppression by pre-treatment in the FCAD process. Carbonaceous contamination (organic and carbidic) resulting from incomplete removal of the organic precursor is the major cause of the poorer sealing properties of the ALD film. No coating dissolution is demonstrated in neutral or acid 0.2 M NaCl solutions. In acid solution localized corrosion by pitting proceeds faster with the ALD than with the FCAD coating. The roles of the pre-existing channel defects exposing the substrate surface and of the spurious interfacial oxide promoting coating breakdown and/or delamination are emphasized

60

Marine corrosion of mild steel at Lumut, Perak  

Science.gov (United States)

The corrosion rate of structural steels in the adverse marine and offshore environments affects the economic interest of offshore structures since the loss of steel may have significant impact on structural safety and performance. With more emphasis to maintain existing structures in service for longer time and hence to defer replacement costs, there is increasing interest in predicting corrosion rate at a given location for a given period of exposure once the protection coating or cathodic protection is lost. The immersion depth, salinity, steel composition and water pollution will be taken into account. Various corrosion allowances are prescribed for structural members by different standards. There are no studies to determine the appropriate corrosion allowance for steel structures in marine environment in Malaysia. The objectives of the research are to determine the nature and rate of corrosion in mm/year for steel structures in marine environment. It also tries to identify whether the corrosion rate is affected by differences in the chemical composition of the steels, and microalgae. Two sets of corrosion coupons of Type 3 Steel consisting of mild steel were fabricated and immersed in seawater using steel frames. The corrosion rate of the coupon in mm/ per year is estimated based on the material weight loss with time in service. The results are compared with recommendations of the code.

Ting, Ong Shiou; Potty, Narayanan Sambu; Liew, Mohd. Shahir

2012-09-01

61

Surface Analysis of Carbon Steel Protected from Corrosion by a New Ternary Inhibitor Formulation Containing Phosphonated Glycine, Zn2+ and Citrate  

Directory of Open Access Journals (Sweden)

Full Text Available Studies on surface analysis of carbon steel protected from corrosion in low chloride and nearly neutral aqueous environment by a synergistic mixture containing N,N-bis(phosphonomethyl glycine (BPMG, zinc ions and citrate ions are presented. The effect of addition of citrate to the binary system, BPMG-Zn2+, is quite significant and is well explored through various studies. The surface protective nature is maintained in the pH range 5 - 9. Potentiodynamic polarization studies inferred that the ternary inhibitor is a mixed inhibitor. Impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the chosen environment. X-ray photoelectron spectroscopic (XPS analysis of the surface film showed the presence of the elements namely iron, phosphorus, nitrogen, carbon, oxygen and zinc. Deconvolution spectra of these elements in the surface film inferred the presence of oxides/hydroxides of iron(III, Zn(OH2 and [Fe(III, Zn(II-BPMG-citrate] heteropolynuclear multiligand complex. This inference is further supported by the reflection absorption Fourier transform infrared spectrum of the surface film. Analysis by scanning electron microscopy (SEM is presented for both the corroded and protected metal surfaces. Based on all these results, a plausible mechanism of corrosion inhibition is proposed.

Boyapati Venkata Appa Rao

2013-01-01

62

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)

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 Herstellung komplizierter, beanspruchungsgerechter Formen im crashrelevanten Karosseriebereich. Der Einsatz dieser Stahlqualitaeten erfolgt bislang in Strukturbauteilen, die mit einem Schmelztauchueberzug aus FeAl7, sog. Usibor, vor Korrosion geschuetzt sind. Jedoch besteht zurzeit keine serienreife Loesung fuer den nachtraeglichen Korrosionsschutz von bereits warmumgeformten Bauteilen. Deshalb wurde ein Korrosionsschutzsystem auf Basis des herkoemmlichen Schmelztauchverzinkungsprozesses entwickelt und appliziert. Zunaechst wurde das Entfestigungsverhalten des hoechstfesten Substrats 22MnB5 analysiert. Anschliessend wurde ein Legierungssystem entwickelt und appliziert. Die so entstandenen Korrosionsschutzschichten wurden hinsichtlich ihrer Struktur und des Korrosionsschutzpotenzials charakterisiert. Im Ergebnis tritt eine deutliche Verbesserung des Korrosionsverhaltens ein. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

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

63

The corrosion protection of metals by ion vapor deposited aluminum  

Energy Technology Data Exchange (ETDEWEB)

A study of the corrosion protection of substrate metals by ion vapor deposited aluminum (IVD Al) coats has been carried out. Corrosion protection by both anodized and unanodized IVD Al coats has been investigated. Base metals included in the study were 2219-T87 Al, 7075-T6 Al, Titanium-6 Al-4 Vanadium (Ti-6Al-4V), 4130 steel, D6AC steel, and 4340 steel. Results reveal that the anodized IVD Al coats provide excellent corrosion protection, but good protection is also achieved by IVD Al coats that have not been anodized.

Danford, M.D.

1993-10-01

64

The Corrosion Protection of Metals by Ion Vapor Deposited Aluminum  

Science.gov (United States)

A study of the corrosion protection of substrate metals by ion vapor deposited aluminum (IVD Al) coats has been carried out. Corrosion protection by both anodized and unanodized IVD Al coats has been investigated. Base metals included in the study were 2219-T87 Al, 7075-T6 Al, Titanium-6 Al-4 Vanadium (Ti-6Al-4V), 4130 steel, D6AC steel, and 4340 steel. Results reveal that the anodized IVD Al coats provide excellent corrosion protection, but good protection is also achieved by IVD Al coats that have not been anodized.

Danford, M. D.

1993-01-01

65

Sol-gel deposition of ZrO2 films in air and in oxygen-free atmospheres for chemical protection of 304 stainless steel : a comparative corrosion study  

OpenAIRE

ZrO2 coatings for corrosion protection were deposited on 304 stainless steel by sol-gel method using zirconium propoxide as precursor and densified in air and in oxygen-free (argon or nitrogen) atmospheres. XRD and IR data of the films were practically independent of the atmosphere used in the densification step showing that the ceramic oxide is properly formed from the precursor. The corrosion behavior of the stainless steel substrate was studied by potentiodynamic polarization curves in the...

Aegerter, Michel A.; Lima-neto, P.; Perdomo, L. F.; Avaca, Luis A.

1999-01-01

66

Some peculiarities of corrosion of wheel steel  

OpenAIRE

Corrosion mechanism and rate of different chemical composition and structural condition of wheel steel were investigated. It was shown that “white layers”, variation in grain size and banding of wheel steel structure results in corrosion rate. Microstructure of steel from different elements of railway wheels after operation with corrosion was investigated. Wheel steel with addition of vanadium corroded more quickly than steel without vanadium. Non-metallic inclusions are the centre of cor...

Shramko, Alexander; Kozlowsky, Alfred; Belaja, Elena; Proidak, Yuriy; Pinchuk, Sofia; Gubenko, Svetlana

2009-01-01

67

Atmospheric corrosion of mild steel  

Directory of Open Access Journals (Sweden)

Full Text Available The atmospheric corrosion of mild steel is an extensive topic that has been studied by many authors in different regions throughout the world. This compilation paper incorporates relevant publications on the subject, in particular about the nature of atmospheric corrosion products, mechanisms of atmospheric corrosion and kinetics of the atmospheric corrosion process, paying special attention to two matters upon which relatively less information has been published: a the morphology of steel corrosion products and corrosion product layers; and b long-term atmospheric corrosion ( > 10 years.

La corrosión atmosférica del acero suave es un tema de gran amplitud que ha sido tratado por muchos autores en numerosas regiones del mundo. Este artículo de compilación incorpora publicaciones relevantes sobre esta temática, en particular sobre la naturaleza de los productos de corrosión atmosférica, mecanismos y cinética de los procesos de corrosión atmosférica, prestando una atención especial a dos aspectos sobre los que la información publicada ha sido menos abundante: a morfología de los productos de corrosión del acero y capas de productos de corrosión, y b corrosión atmosférica a larga duración (> 10 años.

Morcillo, M.

2011-10-01

68

Machineries corrosion and protection  

International Nuclear Information System (INIS)

Author.The phenomena of corrosion in acquiring increasing attention due to wear of friction parts in machines that will lead to loss of efficiency of these parts and decrease of the quality of the products in addition to the threat to industrial security beside massive power consumption used to operate these parts and machines. Some 30% of the national income in developed countries is wasted in replacement and maintenance of corroded parts in machines in spite of massive efforts to control this important economic issue. These parts will discuss the topic of corrosion in machines, types and causes, the methods to control and protection. There are lots of ways to confront and protect machines from corrosion of which: To depend on lubrication through injecting oil under definite pressure to reach friction parts, this can be managed more easily by supplying contact surfaces with holes for oil to reach the area of contact. Through selection of highly resistant metals for corrosion and highly resistant for high temperature solid and durable metals. To resort to know thermal treatment as to form hard surface layer to bear the applied load through nitrogen case hardening and carbonization or sulphurization. To depend on optimum design for friction parts as to lessen the friction factor, in using ball bearing instead of slide bearing in this field. To use surface membranes that adhere to the surface of solid body to protect this surface and to bear friction, in this way it wile and to bear friction, in this way it will erode and be replaced; thickness of this layer ranges between few microns and millimeters, like those layers produced through expulsive painting, chemical reaction, or through magnetic fields wrapping or wrapping using titanium azotic layer through employment for plasma current

69

BWR steel containment corrosion  

International Nuclear Information System (INIS)

The report describes regulatory actions taken after corrosion was discovered in the drywell at the Oyster Creek Plant and in the torus at the Nine Mile Point 1 Plant. The report describes the causes of corrosion, requirements for monitoring corrosion, and measures to mitigate the corrosive environment for the two plants. The report describes the issuances of generic letters and information notices either to collect information to determine whether the problem is generic or to alert the licensees of similar plants about the existence of such a problem. Implementation of measures to enhance the containment performance under severe accident conditions is discussed. A study by Brookhaven National Laboratory (BNL) of the performance of a degraded containment under severe accident conditions is summarized. The details of the BNL study are in the appendix to the report

70

BWR steel containment corrosion  

Energy Technology Data Exchange (ETDEWEB)

The report describes regulatory actions taken after corrosion was discovered in the drywell at the Oyster Creek Plant and in the torus at the Nine Mile Point 1 Plant. The report describes the causes of corrosion, requirements for monitoring corrosion, and measures to mitigate the corrosive environment for the two plants. The report describes the issuances of generic letters and information notices either to collect information to determine whether the problem is generic or to alert the licensees of similar plants about the existence of such a problem. Implementation of measures to enhance the containment performance under severe accident conditions is discussed. A study by Brookhaven National Laboratory (BNL) of the performance of a degraded containment under severe accident conditions is summarized. The details of the BNL study are in the appendix to the report.

Tan, C.P.; Bagchi, G.

1996-04-01

71

Evaluation and control of environmental corrosion for aluminum and steel alloys  

Science.gov (United States)

Corrosion protection systems for aerospace application and the effects of surface treatments and methods of controlling stress corrosion are evaluated. Chromate pigmented systems were found to be most effective for aluminum alloys; zinc-rich coatings gave the greatest protection to steel alloys. Various steel and aluminum alloys are rated for stress corrosion resistance.

Franklin, D. B.

1977-01-01

72

Tests Of Protective Coats For Carbon Steel  

Science.gov (United States)

Report describes laboratory and field tests of candidate paints (primers, tie coats, and topcoats) for use in protecting carbon-steel structures against corrosion in seaside environment at Kennedy Space Center. Coating materials selected because of utility in preventing corrosion, also on basis of legal requirements, imposed in several urban areas, for reduction of volatile organic contents.

Macdowell, Louis G., III

1995-01-01

73

Corrosion of carbon steel welds  

International Nuclear Information System (INIS)

This report assesses the factors which cause preferential attack to occur in carbon steel fusion welds. It was concluded that the main factors were: the inclusion content of the weld metal, the potential of the weld metal being less noble than that of the parent, and the presence of low-temperature transformation products in the heat-affected zone of the weld. These factors should be minimized or eliminated as appropriate so that the corrosion allowances determined for carbon steel waste drums is also adequate for the welds. An experimental/theoretical approach is recommended to evaluate the relative corrosion resistance of welds prepared from BS 4360 grade 43A steel to that of the parent material. (author)

74

Characterization of SiO2-TiO2 Hybrid Corrosion Protective Coatings on Mild Steel  

Science.gov (United States)

Organic-inorganic SiO2-TiO2 sol-gel coatings were prepared and applied on a mild steel substrate using dip coating technique and subsequently heat treated at 200 and 300 °C to improve the corrosion resistance. The coating sols were synthesized using Glycidoxytrimethoxysilane and titanium tetraisopropoxide as precursor materials. The corrosion resistances of the both coated and uncoated samples were evaluated by the Tafel polarization and electrochemical impedance spectroscopy in NaCl solution. The microstructure of coated specimens was characterized by scanning electron microscopy. Fourier transformed infrared and energy dispersive spectroscopy analyses were used to identify the presence of various functional groups in the coating solutions. A comparison of the corrosion resistance of the coated and uncoated mild steel was presented. i corr values of coated specimens heat treated at 200 °C were between 6.9 and 9.2 times smaller than those of uncoated specimen. In the case of coated specimens heat treated at 300 °C, i corr values were 4.4 and 5 times smaller than those of uncoated specimen. The coating film was noted to be smooth and between 7.2- and 7.5-µm thick. The measured electrochemical parameters indicated that the corrosion resistance was improved by the coating film. The elasticity of the coating can be improved by the presence of organic groups in the coating which reduces stress and crack formations during sintering. Ultimately, crack-free and elastic coating was obtained by heat treating of organic-inorganic coating at as low as 200 °C.

Kirtay, Sebahattin

2014-12-01

75

Oxide and nitride protective layers formed on stainless steel by thermal treatment: SEM, AES, WDS and corrosion measurements  

OpenAIRE

Protective oxide and/or nitride layers on AISI 321 stainless steel were prepared by thermal treatment in air and two controlled atmospheres in a laboratory simulation of an actual technological procedure. Samples’ surface was imaged by Scanning Electron Microscopy (SEM), elemental composition of the substrates was checked by Wavelength Dispersive Spectroscopy (WDS) and depth profiles of the samples were measured by Auger Electron Spectroscopy (AES). Since protective layer thicknesses were f...

Jenko, M.; Torkar, M.; Lamut, M.; Kocijan, A.; Godec, M.; Mandrino, Dj

2008-01-01

76

Influence of heat treatment on corrosive resistance of concrete steels  

International Nuclear Information System (INIS)

The reinforcing bars are essential elements of ferro-concrete structures. During the building structure service the reinforcing bars should co-operate with surrounding concrete. Any bonding defects as well as corrosion induced strength reduction may result in construction failure. The reinforcing steel working environment is determined by concrete chemical and phase composition and surrounding environmental properties. The aggressive corrosive activity of the letter implies necessity of effective ways development to protect elements against corrosion. The effect of heat treatment, increased Si content in steel on corrosion resistance of reinforcing steel in concrete was studied in the current work. Corrosion tests and metallographic examinations proved a positive influence of hardening and Si enrichment on corrosion resistance of reinforcing bars in ferro-concrete structures. (author)

77

Electrodeposition of polyaniline–carbon nanotubes composite films and investigation on their role in corrosion protection of austenitic stainless steel by SNIFTIR analysis  

International Nuclear Information System (INIS)

Composite films of polyaniline (PANI) and carbon nanotubes (CNTs) were prepared by electrochemical co-deposition from solutions of the corresponding monomer containing two different kinds of CNTs. The first type was commercial (diameter = 110–170 nm, length = 5–9 ?m) and the second one was home-made (diameter = 30 nm, length = 5–20 ?m). The electrochemical behaviour of PANI–CNTs composite films was investigated with Cyclic Voltammetry and the surface morphology was analysed by Scanning Electron Microscopy (SEM). Subtractively Normalised Interfacial FT-IR procedure was used to investigate the presence of corrosion products when the films were deposited on stainless steel substrates and exposed to acid environment. The spectral investigations were utilised to understand the role of composite films in the corrosion protection and to discriminate the best performance CNTs.

78

Recent trend of corrosion resistant stainless steel  

International Nuclear Information System (INIS)

In severe corrosive environment, the stainless steel having excellent workability and weldability has been used. On the other hand, new corrosive environment has been created by the heightening of industrial equipment efficiency and the development of new processes. In response to the needs of economical corrosion resistant materials withstanding this environment, coupled with the advance of manufacturing techniques, many new corrosion resistant stainless steels have been developed. Generally corrosion is divided into dry corrosion and wet corrosion, but in this report, only the wet corrosion is taken up as there have been many cases of wet corrosion. The trend of development of high purity ferritic stainless steel, corrosion resistant two-phase stainless steel, and highly corrosion resistant stainless steel by the effective utilization of nitrogen is outlined. The high purity ferritic stainless steel was developed by new steel making technology such as VOD, AOD, RH-OB and SS-VOD processes. The two-phase stainless steel is composed of austenite phase and ferrite phase in the ratio of nearly 1:1, and characterized by the high contents of Cr and Mo and the addition of N. About 0.1 % of nitrogen is added to austenitic stainless steel to stabilize and strengthen austenite and prevent the formation of the layer short of Cr. (Kako, I.)

79

Thermally Sprayed Aluminum (TSA) with Cathodic Protection as Corrosion Protection for Steel in Natural Seawater : Characterization of Properties on TSA and Calcareous Deposit  

OpenAIRE

Cathodic protection is an effective corrosion protection for structures submerged in seawater. In addition to applying the current need to lower the metal below the protection potential, a resulting increase in interfacial pH leads to precipitation of calcareous deposit. This deposited layer act as a barrier against oxygen diffusion on the surface, hence lowering the current demand of the structure. However, this layer will also hinder the thermal conductivity, and is therefore unwanted at th...

Egtvedt, Solveig

2011-01-01

80

Synthesis and application of hybrid polymer composites based on silver nanoparticles as corrosion protection for line pipe steel.  

Science.gov (United States)

A facile method was developed to synthesize in high yield dispersed silver nanoparticles (AgNPs) with small particle sizes of less than 10 nm. Silver nitrate was reduced to silver nanoparticles by p-chloroaniline in the presence of polyoxyethylene maleate 4-nonyl-2-propylene-phenol (NMA) as a stabilizer. The produced AgNPs were used to prepare hybrid polymer based on N-isopropylacrylamide (NIPAm), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), N,N-methylenebisacrylamide (MBA) and potassium persulfate (KPS) using a semi-batch solution polymerization method. The prepared AgNPs and hybrid polymer were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM). The corrosion inhibition activity of the AgNPs and hybrid polymer towards steel corrosion in the presence of hydrochloric acid has been investigated by polarization and electrochemical impedance spectroscopy (EIS) methods. Polarization measurements indicate that the AgNPs and hybrid polymer acts as a mixed type-inhibitor and the inhibition efficiency increases with inhibitor concentration. The results of potentiodynamic polarization and EIS measurements clearly showed that the inhibition mechanism involves blocking of the steel surface by inhibitor molecules via adsorption. PMID:24840897

Atta, Ayman M; El-Mahdy, Gamal A; Al-Lohedan, Hamad A; Ezzat, Abdurrahman O

2014-01-01

81

Corrosion in carbon steel service water piping  

International Nuclear Information System (INIS)

Corrosion in carbon steel service water piping presents the designer with a challenge in selecting an appropriate corrosion allowance for these systems. Important corrosion mechanisms such as microbiologically induced pitting corrosion should be considered. Factors that influence the corrosion rate include water quality, water temperature, and service life. Effective chemical treatment can reduce corrosion rates. Although the designer may be able to incorporate features into the design to minimize the effects of corrosion, carbon steel may not always be an appropriate material for this application

82

Failure mechanism of thin Al{sub 2}O{sub 3} coatings grown by atomic layer deposition for corrosion protection of carbon steel  

Energy Technology Data Exchange (ETDEWEB)

Combined analysis by electrochemical impedance spectroscopy (EIS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and field emission scanning electron microscopy (FESEM) of the corrosion protection provided to carbon steel by thin (50 nm) Al{sub 2}O{sub 3} coatings grown by atomic layer deposition (ALD) and its failure mechanism is reported. In spite of excellent sealing properties, the results show an average dissolution rate of the alumina coating of {approx}7 nm h{sup -1} in neutral 0.2 M NaCl and increasing porosity of the remaining layers with increasing immersion time. Alumina dissolution is triggered by the penetration of the solution via cracks/pinholes through the coating to the substrate surface where oxygen reduction takes place, raising the pH. At defective substrate surface sites of high aspect ratio and concentrated residual mechanical stress (along scratches) presumably exposing a higher steel surface fraction, localized dissolution of the coating is promoted by a more facile access of the solution to the substrate surface enhancing oxygen reduction. De-adhesion of the coating is also promoted in these sites by the ingress of the anodic dissolution trenching the steel surface. Localized corrosion of the alloy (i.e. pitting) is triggered prior to complete dissolution of the alumina film on the elsewhere still coated surface matrix.

Diaz, Belen [Chimie ParisTech, Laboratoire de Physico-Chimie des Surfaces (LPCS), 11 rue Pierre et Marie Curie, F-75005 Paris (France); CNRS UMR 7045, 11 rue Pierre et Marie Curie, F-75005 Paris (France); Haerkoenen, Emma [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland); Maurice, Vincent, E-mail: vincent-maurice@chimie-paristech.fr [Chimie ParisTech, Laboratoire de Physico-Chimie des Surfaces (LPCS), 11 rue Pierre et Marie Curie, F-75005 Paris (France); CNRS UMR 7045, 11 rue Pierre et Marie Curie, F-75005 Paris (France); Swiatowska, Jolanta; Seyeux, Antoine [Chimie ParisTech, Laboratoire de Physico-Chimie des Surfaces (LPCS), 11 rue Pierre et Marie Curie, F-75005 Paris (France); CNRS UMR 7045, 11 rue Pierre et Marie Curie, F-75005 Paris (France); Ritala, Mikko, E-mail: Mikko.Ritala@Helsinki.fi [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland); Marcus, Philippe, E-mail: philippe-marcus@chimie-paristech.fr [Chimie ParisTech, Laboratoire de Physico-Chimie des Surfaces (LPCS), 11 rue Pierre et Marie Curie, F-75005 Paris (France); CNRS UMR 7045, 11 rue Pierre et Marie Curie, F-75005 Paris (France)

2011-11-01

83

Corrosion Characteristics Of Aluminum And Stainless Steel  

International Nuclear Information System (INIS)

Corrosion phenomena on metals and alloys often need serious treatment, because such phenomena affect to the lifetime of the materials . Even in certain cases, unsupervised and uncontrolled corrosion processes my result in an installation accident. This study investigates corrosion phenomena n metals, among others are conditions which affect corrosion and its kinds occurring on aluminum and stainless steel

84

Monitoring corrosion of steel bars in reinforced concrete structures.  

Science.gov (United States)

Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion. PMID:24558346

Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

2014-01-01

85

A STUDY OF CORROSION AND STRESS CORROSION CRACKING OF CARBON STEEL NUCLEAR WASTE STORAGE TANKS  

Energy Technology Data Exchange (ETDEWEB)

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.

BOOMER, K.D.

2007-08-21

86

A STUDY OF CORROSION AND STRESS CORROSION CRACKING OF CARBON STEEL NUCLEAR WASTE STORAGE TANKS  

International Nuclear Information System (INIS)

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

87

PROTECCIÓN CONTRA LA CORROSIÓN POR SALES FUNDIDAS DE UN ACERO AL CARBONO POR ROCIADO TERMICO / (PROTECTION AGAINST THE HOT CORROSION OF CARBON STEEL BY THERMAL SPRAYING)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Se evaluó la corrosión por sales fundidas mediante la técnica gravimétrica en un acero de bajo carbono rociado térmicamente con una aleación de acero inoxidable, en una mezcla de sal con 20% Na2SO4 - 80% V2O5, entre 700ºC - 850ºC. Los resultados de las pruebas gravimétricas mostraron una deficiente [...] protección de la capa rociada térmicamente y se presentó alta degradación en el recubrimiento protector, debido a que las temperaturas de exposición fueron mayores que las temperaturas de fusión de las sales. Se concluyó que la velocidad de corrosión aumenta con la temperatura y disminuye con el tiempo de exposición. Abstract in english The hot corrosion was evaluated by gravimetric techniques in a low carbon steel protected by thermal spraying with a stainless alloy, in a mixture of salt 20% Na2SO4 - 80% V2O5, between 700ºC - 850ºC.. The gravimetric tests showed a weak protection of the layer thermal spraying. The test results sho [...] wed a weak protection of the layer thermally sprayed and presented high degradation in the protective coatings because the exposure temperatures were higher than merging temperatures of the salts. It was concluded that the rate of corrosion increases with temperature and decreases with time of exposure.

JOSE, MARULANDA; ANDRÉS, GARCÍA; JOSE, VITOLA.

2009-06-01

88

Assessing resistance of stabilized corrosion resistant steels to intergranular corrosion  

International Nuclear Information System (INIS)

Resistance to intergranular corrosion was determined for four types of titanium-stabilized steels from the coefficients of stabilization efficiency according to the degree the chemical composition was known. The ATA SUPER steel showed the highest resistance parameter value. The resistance of this type of steel of a specific composition, showing a relatively low value of mean nitrogen content was compared with steel of an optimized chemical composition and with low-carbon niobium stabilized, molybdenum modified steels. The comparison showed guarantees of a sufficient resistance of the steel to intergranular corrosion. The method of assessing the resistance to intergranular corrosion using the calculation of the minimum content of Cr', i.e., the effective chromium content, and the maximum effective carbon content C' giving the resistance parameter k seems to be prospective for practical use in the production of corrosion resistant steels. (author). 1 tab., 5 figs., 15 refs

89

Microbial corrosion and cracking in steel. A concept for evaluation of hydrogen-assisted stress corrosion cracking in cathodically protected high-pressure gas transmission pipelines  

DEFF Research Database (Denmark)

An effort has been undertaken in order to develop a concept for evaluation of the risk of hydrogen-assisted cracking in cathodically protected gas transmission pipelines. The effort was divided into the following subtasks: A. Establish a correlation between the fracture mechanical properties of high-strength pipeline steel and the concentration of hydrogen present in the steel. B. Determine the degree hydrogen absorption by cathodically protected steel exposed in natural soil sediment, which include activity of sulphate-reducing bacteria (SRB). C. Compare the above points with fracture mechanical considerations on the level of stress intensity actually present in pipelines during normal operational conditions. The results were used for a discussion - based on well established fracture mechanical relations - on which set of conditions (CP-level and operating pipeline pressure) could give crack propagation. This resulted in threshold curves that can be used for assessment of the risk of hydrogen-assisted cracking as a function of operating pressure and hydrogen content - having the flaw size as discrete parameter. The results are to be used mainly on a conceptual basis, but it was indicated that the requirements for crack propagation include an overprotective CP-condition, a severe sulphate-reducing environment, as well as a large flaw (8 mm or a leak in the present case). A 1 mm flaw (which may be the maximum realistic flaw size) is believed to be unable to provoke crack propagation in this steel.

Nielsen, Lars Vendelbo

1998-01-01

90

Protection of mild steel corrosion with Schiff bases in 0.5 M H2SO4 solution  

International Nuclear Information System (INIS)

Three new Schiff bases, viz., N,N'-ethylen-bis (salicylideneamino) [S1], N,N'-isopropenyl-bis (salicylideneamino) [S2], and N-acetylacetone imine, N'-(2-hydroxybenzophenone imine) ortho-phenyl en [S3] have been investigated as corrosion inhibitors for mild steel in 0.5 M H2SO4 using Tafel polarization and electrochemical impedance spectroscopy (Ei). The three Schiff bases function as good inhibitors reaching inhibition efficiencies of ?97-98% at 300 ppm concentration. The fraction of the metal surface covered by the inhibitor is found to increase with inhibitor concentration. Of the three Schiff bases, the S shows better efficiency than the other two Schiff bases. The adsorption of the inhibitor follows Langmuir isotherm. Thermodynamic calculations indicate the adsorption to be physical in nature

91

Corrosion protection with eco-friendly inhibitors  

Science.gov (United States)

Corrosion occurs as a result of the interaction of a metal with its environment. The extent of corrosion depends on the type of metal, the existing conditions in the environment and the type of aggressive ions present in the medium. For example, CO3?2 and NO?3 produce an insoluble deposit on the surface of iron, resulting in the isolation of metal and consequent decrease of corrosion. On the other hand, halide ions are adsorbed selectively on the metal surface and prevent formation of the oxide phase on the metal surface, resulting in continuous corrosion. Iron, aluminum and their alloys are widely used, both domestically and industrially. Linear alkylbenzene and linear alkylbenzene sulfonate are commonly used as detergents. They have also been found together in waste water. It is claimed that these chemicals act as inhibitors for stainless steel and aluminum. Release of toxic gases as a result of corrosion in pipelines may lead in certain cases to air pollution and possible health hazards. Therefore, there are two ways to look at the relationship between corrosion and pollution: (i) corrosion of metals and alloys due to environmental pollution and (ii) environmental pollution as a result of corrosion protection. This paper encompasses the two scenarios and possible remedies for various cases, using 'green' inhibitors obtained either from plant extracts or from pharmaceutical compounds. In the present study, the effect of piperacillin sodium as a corrosion inhibitor for mild steel was investigated using a weight-loss method as well as a three-electrode dc electrochemical technique. It was found that the corrosion rate decreased as the concentration of the inhibitor increased up to 9×10?4?M 93% efficiency was exhibited at this concentration.

Shahid, Muhammad

2011-12-01

92

Corrosion protection with eco-friendly inhibitors  

International Nuclear Information System (INIS)

Corrosion occurs as a result of the interaction of a metal with its environment. The extent of corrosion depends on the type of metal, the existing conditions in the environment and the type of aggressive ions present in the medium. For example, CO3?2 and NO?3 produce an insoluble deposit on the surface of iron, resulting in the isolation of metal and consequent decrease of corrosion. On the other hand, halide ions are adsorbed selectively on the metal surface and prevent formation of the oxide phase on the metal surface, resulting in continuous corrosion. Iron, aluminum and their alloys are widely used, both domestically and industrially. Linear alkylbenzene and linear alkylbenzene sulfonate are commonly used as detergents. They have also been found together in waste water. It is claimed that these chemicals act as inhibitors for stainless steel and aluminum. Release of toxic gases as a result of corrosion in pipelines may lead in certain cases to air pollution and possible health hazards. Therefore, there are two ways to look at the relationship between corrosion and pollution: (i) corrosion of metals and alloys due to environmental pollution and (ii) environmental pollution as a result of corrosion protection. This paper encompasses the two scenarios and possible remedies for various cases, using 'green' inhibitors obtained either from plant extracts or from pharmaceutical compounds. In the present study, the effect of piperacillin sodium as a corrosion inhibitor for mild steel was investigated using a weight-loss method as well as a three-electrode dc electrochemical technique. It was found that the corrosion rate decreased as the concentration of the inhibitor increased up to 9×10?4?M; 93% efficiency was exhibited at this concentration. (review)

93

Corrosion of Steel in Concrete, Part I – Mechanisms  

DEFF Research Database (Denmark)

Throughout the world reinforced concrete is the most widely used construction material for buildings and civil engineering structures. Most reinforced concrete structures have performed satisfactory over many decades, but there still is an unacceptable large number of structures that deteriorate prematurely. Reinforcement corrosion is identified to be the foremost cause of deterioration. Steel in concrete is normally protected by a passive layer due the high alkalinity of the concrete pore solution; corrosion is initiated by neutralization through atmospheric carbon dioxide and by ingress of depassivation ions, especially chloride ions. The background and consequences of deterioration of reinforced concrete structures caused by steel corrosion are summarized. Selected corrosion mechanisms postulated in the literature are briefly discussed and related to observations. The key factors controlling initiation and propagation of corrosion of steel in concrete are outlined.

Küter, André; MØller, Per

2006-01-01

94

Corrosion protection at Crimean NPP  

International Nuclear Information System (INIS)

Coal-epoxide compositions modified by adsorption-active additions as well as reinforced coatings of the same type for pipeline protection against soil corrosion are investigated to provide for corrosion protection of water-supply systems at the Crimean NPP. Laboratory test in the Asov Sea water at 50-90 deg C confirmed the reliability of the coatings proposed. Works on NPP pipeline protection are performed using the coatings recommended which appeared to be quite efficient for construction and assemling works and as a result of corrosion prevention a sufficient economic effect (1.16 millions of roubles) is abtained

95

METHOD FOR ARRANGEMENT OF HIGH-STRENGTH CORROSION-RESISTANT FOR EFFICIENT PROTECTION OF STEEL PIPELINES OPERATED IN THE EXTREME NORTH  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement. At present, the problem of main pipeline protection from corrosion is extremelyimportant. Principal gas-transport routes have the biggest length in the North areas whereclimatic and geotechnical conditions are adverse. Scientists of Voronezh State University of Architectureand Civil Engineering have developed new material, rubber concrete. This material isbased on liquid oligodienes and has unique set of operational characteristics. The material can beefficiently used as insulation material for metal pipe in the conditions of the Extreme North.Results. The method for arrangement of protective coating of metal pipe is developed on the basisof rubber concrete. The method is patented. Laboratory device which allows one to perform structuresformation of rubber mastic on the surface of metal pipe is constructed. Physicomechanicalproperties of rubber concrete as insulation material for steel pipes are determined.Conclusions. The results of experiments allow us to draw a conclusion on the expediency of the useof rubber concrete as a protection coating material for steel pipes operated in the Extreme North.

I. S. Surovtsev

2011-11-01

96

Corrosion pitting of stainless steels  

Energy Technology Data Exchange (ETDEWEB)

The work presented elucidates the problem of distinguishing between anodic and cathodic sites of pitting corrosion in standard stainless steels 304 and 316. In the present work pitting has been formed by the immersion of samples in magnesium chloride solution (MgCl/sub 2/) for a given time and this was confirmed by Scanning Auger Microscope (SAM) study. These results show the presence of the elements at the pits and surrounding pits. The following conclusion was obtained from the result: the resistivity of the passive film in MgCl/sub 2/ solution increases with increasing amount of chromium content in the film.

Muhamad Daud (PUSPATI, Selangor (Malaysia))

1984-06-01

97

Corrosion of Electrogalvanized Steel in 0.1 M NaCl Studied by SVET  

Scientific Electronic Library Online (English)

Full Text Available The corrosion of electrogalvanized steel exposed to 0.1 M NaCl was studied using the SVET. Situations of localized corrosion, cathodic protection and corrosion protection due to surface pre-treatment were analyzed, putting in evidence the possibilities of the technique. [...

A.C., Bastos; A.M., Simões; M.G., Ferreira.

98

Corrosion of Electrogalvanized Steel in 0.1 M NaCl Studied by SVET  

OpenAIRE

The corrosion of electrogalvanized steel exposed to 0.1 M NaCl was studied using the SVET. Situations of localized corrosion, cathodic protection and corrosion protection due to surface pre-treatment were analyzed, putting in evidence the possibilities of the technique.

Bastos, A. C.; Simo?es, A. M.; Ferreira, M. G.

2003-01-01

99

The Corrosion of High Performance Steel in Adverse Environments  

International Nuclear Information System (INIS)

The corrosion products that have formed on weathering steel bridges exposed to different weather conditions in the United States have been evaluated. They have been analyzed by spectroscopic techniques to determine the relationship between protective and non-protective rust coatings, and their relationship to the exposure conditions. Bridges constructed recently using High Performance Steel, as well as older bridges built with Type A588B weathering steel, were evaluated for corrosion performance of the rust coatings. In locations where the steel is subjected to regular wet-dry cycling, where the surface is wet for less than about 20% of the time, a protective patina starts to form after a few months exposure, and continues to an adherent, impervious coating after a decade. The protective patina is characterized by the formation of only goethite and lepidocrocite. The goethite makes up about 80% of the rust, and itself consists of a nanophase component, 40%, or infrequent drying cycles (regions close to waterways, fog or having high humidity), the weathering steel forms a rust coating that consists of a large amount of maghemite, and goethite that contains very little of the nanophase component. The rust coating ex-foliates from the steel and is not protective. Under exposure conditions in which chlorides are deposre conditions in which chlorides are deposited onto the weathering steel surface (marine or de-icing salt locations), the protective patina also does not form. Instead, the rust coating consists of a large fraction of akaganeite that forms at the expense of the lepidocrocite and nanophase goethite. The bridges exposed to high chloride concentrations, 1.5 wt%, and therefore having no protective patina, have corrosion rates measured to be 6 times larger than expected for weathering steel with the protective patina

100

The Corrosion of High Performance Steel in Adverse Environments  

Science.gov (United States)

The corrosion products that have formed on weathering steel bridges exposed to different weather conditions in the United States have been evaluated. They have been analyzed by spectroscopic techniques to determine the relationship between protective and non-protective rust coatings, and their relationship to the exposure conditions. Bridges constructed recently using High Performance Steel, as well as older bridges built with Type A588B weathering steel, were evaluated for corrosion performance of the rust coatings. In locations where the steel is subjected to regular wet-dry cycling, where the surface is wet for less than about 20% of the time, a protective patina starts to form after a few months exposure, and continues to an adherent, impervious coating after a decade. The protective patina is characterized by the formation of only goethite and lepidocrocite. The goethite makes up about 80% of the rust, and itself consists of a nanophase component, 40%, or infrequent drying cycles, (regions close to waterways, fog or having high humidity), the weathering steel forms a rust coating that consists of a large amount of maghemite, and goethite that contains very little of the nanophase component. The rust coating ex-foliates from the steel and is not protective. Under exposure conditions in which chlorides are deposited onto the weathering steel surface, (marine or de-icing salt locations), the protective patina also does not form. Instead, the rust coating consists of a large fraction of akaganeite that forms at the expense of the lepidocrocite and nanophase goethite. The bridges exposed to high chloride concentrations, 1.5 wt%, and therefore having no protective patina, have corrosion rates measured to be 6 times larger than expected for weathering steel with the protective patina.

Cook, Desmond C.

2005-04-01

101

49 CFR 193.2625 - Corrosion protection.  

Science.gov (United States)

... Maintenance § 193.2625 Corrosion protection. (a) Each operator...metallic components could, unless corrosion is controlled, have their...affected by external, internal, or atmospheric corrosion during their intended...

2010-10-01

102

Internal corrosion of carbon steel piping in hot aquifers service  

Directory of Open Access Journals (Sweden)

Full Text Available Internal corrosion of carbon steel pipelines is a major problem encountered in water service. In terms of prediction of the remaining lifetime for water pipelines based on the corrosion allowance, the three main approaches are corrosion modelling, corrosion inhibitor availability, and corrosion monitoring. In this study we used two theoretical corrosion models, CASSANDRA and NORSOK M-506 of quite different origin in order to predict uniform corrosivity of hot aquifers in eight different pipelines. Because of the varying calculation criteria for the different models, these can give very different corrosion rate predictions for the same data input. This is especially true under conditions where the formation of protective films may occur, such as at elevated temperatures. The evaluation of models was conducted by comparison using weight-loss coupons and three corrosion inhibitors were obtained from commercial suppliers. The tests were performed during the 60-day period. Even though inhibitors’ efficiencies of 98% had been achieved in laboratory testing, inhibitors’ availabilities of 85% have been used due to logistics problems and other issues. The results, given in mmpy, i.e. millimeter per year, are very consistent with NORSOK M-506 prediction. This is presumably because the model considers the effect of the formation of a passive iron carbonate film at temperatures above 80 °C and significant reduction in corrosion rate. Corrosion inhibitor A showed a better performance than inhibitors B and C in all cases but the target corrosion rates of less than 0.1 mmpy were achieved for all inhibitors. The chemical type of corrosion inhibitor A is based on quaternary amines mixed with methanol, isopropyl alcohol, xylene and ethylbenzene. Based on the obtained results the carbon steel lifetime of 30 years, provided proper inhibitors are present and 3mm corrosion allowance, can be achieved for hot aquifers service with presented water compositions.

Simi?i? Miloš V.

2011-01-01

103

Non-corrosive steel condenser tubes  

International Nuclear Information System (INIS)

Non-corrosive steels, chiefly 18/8 Chromium-Nickel and 18/10/2 Chromium-Nickel-Molybdenum steels have been used in Germany for condenser tubing for about 15 years. Favourable operating experience is available from sea or river water and closed-circuit cooling systems with moderate salt content. For brackish and sea water cooling, non-corrosive steels with higher resistance against pitting corrosion are required. The development of these types of steels with higher chromium and molybdenium content is described. Operating experience so far with these steels has demonstrated good behaviour in brackish and sea water. Increased use of these steels for condenser tubing can be expected in the future. (orig.)

104

Stainless steel acid corrosion inhibition by organic dyes  

International Nuclear Information System (INIS)

Azobenzene dyes are effective inhibitors for austenitic 304 L and 316 L stainless steel corrosion in high acidic medium up to 7N. A good efficiency is obtained from weight loss and electrochemical Rsub(p) measurements in hydrochloric acid, while no inhibition is observed in sulfuric solutions. Transformation from the primarily azobenzene to other compounds give rise to enhanced protection of steel samples, and probable structures of the inhibiting species are proposed in view of our results

105

Corrosion behaviour of laser clad stainless steels  

International Nuclear Information System (INIS)

The present paper is focussed in the study of the properties of a clad layer of stainless steel on a mild steel. By blowing powder of the alloy into a melt pool generated by a laser of 2 KW, an homogeneous layer of 316 stainless steel can be obtained. Structure, composition and corrosion behaviour are similar to those of a stainless steel in as-received condition. (Author)

106

Corrosion of an austenite and ferrite stainless steel weld  

Directory of Open Access Journals (Sweden)

Full Text Available Dissimilar metal connections are prone to frequent failures. These failures are attributed to the difference in the mechanical properties across the weld, the coefficients of thermal expansion of the two types of steels and the resulting creep at the interface. For the weld analyzed in this research, it was shown that corrosion measurements can be used for a proper evaluation of the quality of weld material and for the prediction of whether or not the material, after the applied welding process, can be in service without failures. It was found that the corrosion of the weld analyzed in this research resulted from the simultaneous activity of different types of corrosion. In this study, electrochemical techniques including polarization and metallographic analysis were used to analyze the corrosion of a weld material of ferrite and austenitic stainless steels. Based on surface, chemical and electrochemical analyses, it was concluded that corrosion occurrence was the result of the simultaneous activity of contact corrosion (ferrite and austenitic material conjuction, stress corrosion (originating from deformed ferrite structure and inter-granular corrosion (due to chromium carbide precipitation. The value of corrosion potential of –0.53 V shows that this weld, after the thermal treatment, is not able to repassivate a protective oxide film.

BRANIMIR N. GRGUR

2011-07-01

107

Corrosion behavior of sensitized duplex stainless steel.  

Science.gov (United States)

The present work investigates the corrosion behavior of 2205 duplex stainless steel in 0.9% NaCl solution after various heat-treatments, and compares it to that of 316L austenitic stainless steel. Both stainless steels were heat-treated at 500, 650, and 800 degrees C in air for 1 h, followed by furnace cooling. Each heat-treated sample was examined for their microstructures and Vickers micro-hardness, and subjected to the X-ray diffraction for the phase identification. Using potentiostatic polarization method, each heat-treated sample was corrosion-tested in 37 degrees C 0.9% NaCl solution to estimate its corrosion rate. It was found that simulated sensitization showed an adverse influence on both steels, indicating that corrosion rates increased by increasing the sensitization temperatures. PMID:9713683

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

1998-01-01

108

Corrosion property of API and modified 13Cr steels in oil and gas environment  

Energy Technology Data Exchange (ETDEWEB)

Effects of environmental factors on general corrosion property of API and modified 13Cr steels were systematically investigated. An essential reaction determining the corrosion rate of steels in CO{sub 2} environment is considered to be a direct reduction reaction of carbonic acid. In the absence of a protective film of corrosion product or passivity, the corrosion rate of steels can be written by an Arrhenius-type equation including parameters of activity of carbonic acid and temperature, and using this equation a safety use limit of each steel in various oil and gas environments can be estimated.

Sakamoto, S.; Maruyama, K. [Nippon Steel Corp., Kitakyushu (Japan). Yawata R and D Lab.; Kaneta, H. [Japan National Oil Corp., Chiba (Japan). Technology Research Center

1996-08-01

109

Effect of chlorides on the corrosion behaviour of mild steel  

International Nuclear Information System (INIS)

In PWR's steam generators, ''denting'' resulted from corrosion of support plate material, carbon steel is an important problem. The role of chlorides in corrosion acceleration of mild steel was studied. Corrosion tests were conducted at temperature from 1000C to 2800C in deaerated solutions of NaCl and MgCl2 which are main content of sea water. 1) Solution of MgCl2 was more corrosive than that of NaCl. The more increased in concentration of each chloride solution, the more corrosive in MgCl2 soln. but the less corrosive in NaCl soln. 2) The rate of corrosion in the mixed solution of NaCl and MgCl2 was governed by the concentration of MgCl2 soln. The corrosion behaviour in sea water was suggested to be not controlled by NaCl but by MgCl2. 3) Acidification of MgCl2 soln. could be evaluated by experiment at 1000C, the degree of acidification increased with increasing the concentration. However, the value of pH during corrosion was kept constant by the concentration of dissolved Fe2+ ions. 4) The corrosion acceleration by MgCl2 soln. was arised not only from acidification by the solution itself but from continuous supplementation of H+ ions with the hydrolysis of dissolved Fe2+ ions. This autocatalytic corrosion process not exhausting acid was characterized with the corrosion in closed system such as in crevice. In additclosed system such as in crevice. In addition to acidification of MgCl2 soln., the formation of non-protective magnetite film by Mg2+ ion was estimated to be a reason of accelerated corrosion. (author)

110

Corrosion and protection of uranium alloy penetrators  

International Nuclear Information System (INIS)

Penetrators made from either a U--3/4 percent Ti alloy or a U--3/4 percent Mo--3/4 percent Zr--3/4 percent Nb--1/2 percent Ti alloy (''Quad'') corrode mildly in moist air, significantly in moist nitrogen, and severely in salt fog. Adequate protection was provided in moist air and nitrogen by coating with electroplated nickel, electroplated nickel and zinc with a chromate finish, and galvanized zinc with a chromate finish. In salt fog, electroplated nickel offered only temporary protection whereas galvanized zinc and electroplated nickel-zinc provided long-lasting protection. The resistance of uncoated penetrators was affected variously by dissimilar metal couplings. Aluminum protected the Quad alloy and adversely affected the U--3/4 percent Ti alloy, whereas steel enhanced localized corrosion in both. (U.S.)

111

Development and testing of powder wires for welding of atmosphere corrosion-resistant steel  

International Nuclear Information System (INIS)

Self-protection powder wires providing for necessary corrosion resistance and mechanical properties of metal joints, corresponding to the properties of the 10KhDP, 10KhNDP and 12KhGDAF steels, are developed. Application of high-alloy steel powders in powder wire blends diminishes the alloy elements spread in the weld metal and increases its corrosion resistance

112

Corrosion Properties of Laser Welded Stainless Steel  

DEFF Research Database (Denmark)

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).

Weldingh, Jakob; Olsen, Flemmming Ove

1997-01-01

113

Corrosion of carbon steel under waste disposal conditions  

International Nuclear Information System (INIS)

The corrosion of carbon steel has been studied in the United Kingdom under granitic groundwater conditions, with pH between 5 and 10 and possibly substantial amounts of Cl-, SO42- and HCO3-/CO32-. Corrosion modes considered include uniform corrosion under both aerobic and anaerobic conditions; passive corrosion; localized attack in the form of pitting or crevice corrosion; and environmentally assisted cracking - hydrogen embrittlement or stress corrosion cracking. Studies of these processes are being carried out in order to predict the metal thicknesses required to give container lifetimes of 500 to 1000 years. A simple uniform corrosion model predicts a corrosion rate of around 13.4 ?m/a at 20C, rising to 69 ?m/a at 50C and 208 ?m/a at 90C. A radiation dose of 105 rad/h and a G-value of 2.8 for the production of oxidizing species would account for an increase in corrosion rate of 7 ?m/a. This model overestimates slightly the results actually achieved for experimental samples exposed for two years, the difference being due to a protective film formed on the samples. These corrosion rates predict that the container must be 227 mm thick to withstand uniform corrosion; however, they predict very high levels of hydrogen production. Conditions will be favourable for localized or pitting corrosion for about 125 years, leading to a maximum penetration of 160 mm. Since the exposure environment cannot be predicted precisely, one cannot state that stress corrosion cracking is impossible. Thus the container must be stress relieved. Other corrosion mechanisms such as microbial corrosion and hydrogen embrittlement are not considered significant

114

Express assessment of inhibition of local steel corrosion in hydrogen sulfide solutions  

International Nuclear Information System (INIS)

For rapid determination of protective concentration (PC) of inhibitors in case of local corrosion (LC) of steels it is suggested that anode polarization at VE = 0.1 mVxs-1 should be used. Remoteness of LC potential (ELC) from corrosion potential (Ecor) serves a criterion for evaluation of protective action of the inhibitors in the course of LC. It is assumed that the inhibitor protects steel from LC if Ecor LC

115

Erosion-corrosion resistance of boronised steels  

Energy Technology Data Exchange (ETDEWEB)

Boronizing has, in addition to carburizing and nitriding, become the frequently applied diffusion technique in the heat-treatment of ferrous materials. After borizing, one layer or two may be formed on the surface. These layers are very hard and confers great resistance both to corrosion and to abrasive wear. Erosion-Corrosion is the first factor which caused damage and abrasion on the material surface. Several studies have been made and put forward the explanations of how the mechanism of corrosion and erosion might interact at the metal surface. In this study, erosion- corrosion and abrasion resistance of mild steels were studied. Erosion-corrosion resistance of boronized steels are determined and compared with untreated materials. Some significant factors and their influence are also considered. (orig.)

Capan, L. (Mechanical Engineering Dept., Istanbul Univ. (Turkey)); Alnipak, B. (Mechanical Engineering Dept., Istanbul Univ. (Turkey))

1994-01-01

116

Stress corrosion of low alloy steel forgings  

International Nuclear Information System (INIS)

The catastrophic failure of a steam turbine rotor disc at Hinkley Point 'A' Power station was shown to have been caused by the growth of a stress corrosion crack to critical dimensions. This failure has promoted great interest in the stress corrosion susceptibility of medium strength low alloy steel forgings in steam environments. Consequently, initiation and growth of stress corrosion cracks of typical disc steels have been investigated in steam and also in water at 950C. Cracking has been shown to occur, predominantly in an intergranular manner, with growth rates of between 10-9 and 10-7 mm sec.-1. It is observed that corrosion pitting and oxide penetration prior to the establishment of a stress corrosion crack in the plain samples. (author)

117

Crevice Corrosion of 321 Stainless Steel in Sodium Chloride Solutions  

International Nuclear Information System (INIS)

Electrochemical techniques have been applied to study the crevice corrosion behaviour of stabilized 321 stainless steel in both 0.5, 1 and 2 M sodium chloride solutions at 25 and 80 degree . This type of stainless steel enjoys a good corrosion resistance especially in the heat affected zone (Haz) of welds. In this investigation the crevice corrosion of 321 stainless steel was studied in both bulk solution environments as well as in chloride solutions simulating those formed inside crevices. A metal-to-nonmetal crevice assembly, in which disc type specimens were faced to a PTFE crevice former, is used for bulk solution tests. Crevice-free specimens of solutions formed inside crevices (known as the critical crevice solutions, CCS). Cyclic potentiodynamic technique was used in evaluating the electrochemical corrosion performance of the alloy in bulk (0.5 and 1 M Nacl) environment. This revealed that both chloride ion concentration and temperature have a marked effect on the electrochemical parameters generally used for the evaluation of the crevice corrosion susceptibility. This included the corrosion potential. E corr. The passivity breakdown potential, Eb, and the protection potential, E p

118

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

International Nuclear Information System (INIS)

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

119

Treatment Prevents Corrosion in Steel and Concrete Structures  

Science.gov (United States)

In the mid-1990s, to protect rebar from corrosion, NASA developed an electromigration technique that sends corrosion-inhibiting ions into rebar to prevent rust, corrosion, and separation from the surrounding concrete. Kennedy Space Center worked with Surtreat Holding LLC, of Pittsburgh, Pennsylvania, a company that had developed a chemical option to fight structural corrosion, combining Surtreat's TPS-II anti-corrosive solution and electromigration. Kennedy's materials scientists reviewed the applicability of the chemical treatment to the electromigration process and determined that it was an effective and environmentally friendly match. Ten years later, NASA is still using this approach to fight concrete corrosion, and it has also developed a new technology that will further advance these efforts-a liquid galvanic coating applied to the outer surface of reinforced concrete to protect the embedded rebar from corrosion. Surtreat licensed this new coating technology and put it to use at the U.S. Army Naha Port, in Okinawa, Japan. The new coating prevents corrosion of steel in concrete in several applications, including highway and bridge infrastructures, piers and docks, concrete balconies and ceilings, parking garages, cooling towers, and pipelines. A natural compliment to the new coating, Surtreat's Total Performance System provides diagnostic testing and site analysis to identify the scope of problems for each project, manufactures and prescribes site-specific solutions, controls material application, and verifies performance through follow-up testing and analysis.

2007-01-01

120

Corrosion of steel tendons used in prestressed concrete pressure vessels  

International Nuclear Information System (INIS)

The purpose of this investigation was to determine the corrosion behavior of a high strength steel (ASTM A416-74 grade 270), typical of those used as tensioning tendons in prestressed concrete pressure vessels, in several corrosive environments and to demonstrate the protection afforded by coating the steel with either of two commercial petroleum-base greases or Portland Cement grout. In addition, the few reported incidents of prestressing steel failures in concrete pressure vessels used for containment of nuclear reactors are reviewed. The susceptibility of the steel to stress corrosion cracking and hydrogen embrittlement and its general corrosion rate were determined in several salt solutions. Wires coated with the greases and grout were soaked for long periods in the same solutions and changes in their mechanical properties were subsequently determined. All three coatings appeared to give essentially complete protection but small flaws in the grease coatings were detrimental; flaws or cracks less than 1 mm wide in the grout were without effect

121

Corrosion of steel tendons used in prestressed concrete pressure vessels  

International Nuclear Information System (INIS)

The corrosion behavior of a high-strength steel [Specifications for Uncoated Seven-Wire-Stress-Relieved Strand for Prestressed Concrete (ASTM A 416-74, Grade 270)], typical of those used as tensioning tendons in prestressed concrete pressure vessels was measured in several corrosive environments. The protection obtained by coating the steel with two commercial petroleum-base greases or with Portland cement grout was evaluated. The few reported incidents of prestressing steel failures in concrete pressure vessels used for containment of nuclear reactors were reviewed. The susceptibility of the steel to stress corrosion cracking and hydrogen embrittlement and its general corrosion rate were determined in several salt solutions. Wires coated with the greases and grout were soaked for long periods in the same solutions and changes in their mechanical properties were subsequently determined. All three coatings appeared to give essentially complete protection; however, flaws in the grease coatings could be detrimental, and flaws or cracks less than 1-mm-wide (0.04 in.) in the grout were without effect

122

Corrosion and deposition of corrosion products on carbon steel and martensitic steel components of CANDU-6 reactor primary circuit  

International Nuclear Information System (INIS)

Cernavoda NPP Unit 1 is a heavy water cooled and moderated CANDU 6 reactor, using natural uranium as fuel. To ensure a minimal degradation of structural materials by fluid contact and to achieve or exceed the design lifetime of the plant, a chemical control and corrosion monitoring program has been established. The corrosion of the Primary Heat Transport System (PHTS) components is minimized by carefully selecting and then controlling a set of chemical parameters to reduce the aggressiveness of the coolant to specific metals used in the system. Chemical control of PHTS and surveillance of structural materials corrosion is directed towards keeping chemical parameters within specified limits in order to minimize corrosion of equipment and related piping, to control the corrosion rate, impurities concentration and fission products and to minimize activity transport and heat transfer surfaces fouling. To monitor the effects of operating chemistry on the corrosion of the system's components and the build-up of activity on construction materials and to show up important effects in the activity transport, an Autoclave System is required. To determine corrosion and to characterize the superficial oxide films formed on carbon and martensitic steel, the following methods have been used: gravimetric, metallographic and electronic microscopy, electrochemical impedance spectroscopy (EIS), X-ray diffraction and XPS. The analysis of the samples exposed for different times in autoclales exposed for different times in autoclaves (197, 371, 568 and 825 days), allowed us to determine the corrosion rate, the deposition and releasing of corrosion products, as well as the characteristics of the corrosive films formed. The results obtained by corrosion analysis of the carbon and martensitic steel coupons exposed in Y1-Y4 autoclaves, assembled in by-pass of CANDU-6 reactor primary circuit from Cernavoda NPP Unit 1 showed the following: - The continuous, adherent and protective oxide films were formed by generalized corrosion of structural materials. By increasing the exposure times better formation of more adherent oxides was evidenced but not any localized corrosion. The corrosion products were mainly magnetite crystalides. Their quantity increased with exposure time and was higher on samples exposed in autoclave circuits in the reactor inlet header, because the magnetite solubility is smaller, the temperature being smaller, and the coolant is probably still supersaturated in iron. The corrosion products release rate and the corrosion rate for carbon steel SA 106 gr.B decreased, while the exposure time increased. The higher values for these rates, especially at the beginning, were obtained on the samples exposed in autoclave circuits from the reactor inlet header

123

Radioindicator methods application for studies corrosion of steels in the gaseous media and liquids  

International Nuclear Information System (INIS)

Corrosion of steels in the city and industrial atmospheres is a considerable problem because of the high content of the sulphur dioxide in these atmospheres. This sulphur dioxide is formed during combustion of the fossile fuels. Corrosion protection is not effective beacause up to now the mechanism of the corrosion process is non completelly clear. Pure electrochemical approach in explanation of the corrosion mechanisms is impossibly mainly because in the connection that periodical presence of electrolyte and commulation of the corrosion stimulators - sulphites accures. Sulphites form agglomerates, being collected in the corrosion products. In the laboratory model conditions the problem of atmospheric corrosion was investigated by means of labelling by radionuclide sulphur-35. The results obtained partly have given explanations of the mechanism of the atmospheric corrosion of steels and also have shown the ways for creation of the more perfect corrosion protection. By means of the tracer technique dissolving of the corrosive-resistant steels in different media was investigated. The results obtained quantatively describe kinetics of the corrosion process and point to the selectivity of corrosion process with preferable extraction into solution od certain components of steel, especially in the initial stages of the process and in transforming of the corrosion process into the passive state. Activity of samples and separate fractions were measured by means of a semiconfuions were measured by means of a semiconfuctor detector with application of a multichannel annalyzer, connected to a computer for processing of the results

124

Chemical mechanism of steels total corrosion and oxidizing in power unit circuits  

International Nuclear Information System (INIS)

Model providing the key to understanding of the experimental data which cannot be explained within the frames of classical electrochemical mechanism of the steels general corrosion is proposed. It is related primary to chemical regularities of corrosion films formation on the steel surfaces to explanation of causes of their different protective properties and defences on the phase composition of the corrosion products, dispersed in a coolant

125

Pitting corrosion protection of stainless steel by sputter deposited hafnia, alumina, and hafnia-alumina nanolaminate films  

International Nuclear Information System (INIS)

316L stainless steel coated with sputter deposited HfO2, Al2O3, and HfO2-Al2O3 nanolaminate films were subjected to direct current cyclic potentiodynamic polarization (DCP) in Hanks' balanced salt solution electrolyte. Postexposure morphology was characterized by scanning electron microscopy (SEM) with in situ energy dispersive spectroscopy (EDS). SEM/EDS data show that bare steel and steel coated with single-layer HfO2 develop pits with perforated covers. These pits become autocatalytic, consistent with an observed positive DCP hysteresis. On the other hand, SEM/EDS data show that steel coated with Al2O3 and HfO2-Al2O3 nanolaminate films does not develop autocatalytic pits, consistent with an observed negative DCP hysteresis. However, Al2O3 splinters upon polarization whereas the HfO2-Al2O3 nanolaminate remains intact. The areas of worst damage in the nanolaminate correspond to pit cover rupture before autocatalysis, allowing pit and bulk electrolyte to mix and the newly exposed steel surface to repassivate. The films' diverse behavior is discussed in terms of a model for perforated pit growth that requires occlusion until an autocatalytic geometry is established. The authors conclude that the key property a film must have to arrest autocatalytic geometry development is the ability tytic geometry development is the ability to rupture locally at an early stage of pit growth.

126

Air crevice corrosion of stainless steels  

International Nuclear Information System (INIS)

Test structures were used to study crevice corrosion of stainless steels, including high-strength ones, in salt fog. Test results enabled to range stainless steels according to their resistance to crevice corrosion in air: resistant steels-12Kh18N10T, 08Kh15N5D2T, 06Kh14N6D2MBT, 13Kh15N4AM3, 08Kh17N5AM3; low-resistant steels - 03Kh10N11M2T, 03Kh12N10MT, 03Kh9N9K5M3, 15Kh16N2AM; nonresistant steels -13Kh11N2V2MF, 20Kh13, 40Kh13, 95Kh18. 19 refs.; 5 tabs

127

Kinetics and structural studies of the atmospheric corrosion of carbon steels in Panama  

International Nuclear Information System (INIS)

The corrosion of a carbon steel was studied in different atmospheres at sites in the Republic of Panama. The weight loss (corrosion penetration) suffered by the carbon steel is related to time by a bilogarithmic law. Moessbauer spectroscopy indicated the rust was composed of non-stoichiometric magnetite (Fe3-xO4), maghemite (?-Fe2O3), goethite (?-FeOOH) of intermediate particle size, lepidocrocite (?-FeOOH) and superparamagnetic particles. Magnetite formation is related to the alternating dry-wet cycles. Goethite is related to corrosion penetration by a saturation type of behavior, following a Langmuir type of relationship. Goethite in rust protects steel against further atmospheric corrosion

128

Corrosion protection at a nuclear power station  

International Nuclear Information System (INIS)

Early in the 1970's, the Electricity Supply Commission (Eskom) in South Africa took the decision to construct South Africa's first nuclear fuelled power station. The environment at Koeberg, however, was determined as being particularly corrosive. Eskom was thus faced with the task of selecting corrosion resistant materials and protective coating systems that would provide the required performance in the hostile marine environment. In order to select the correct coating, it was decided to conduct an investigation into the behaviour of various coating systems. All the major coating suppliers in South Africa were invited to provide wet samples of the coating systems that they would recommend. These coatings were applied to mild steel panels which had been prepared in accordance with the coating manufacturer's specification. The panels were then mounted on exposure test racks at various sites. The results of this coating exposure programme were used in the compilation of the corrosion protection specifications for plant and components exposed to the atmosphere at Koeberg. 1 ill

129

Materials corrosion and protection from first principles  

Science.gov (United States)

Materials erode under environmental stresses such as high temperature, high pressure, and mechanical shock/stress, but erosion is often exacerbated by chemical corrosion. In this dissertation, periodic density functional theory (DFT) is employed to simulate interfacial adhesion, absorption kinetics, bulk diffusion, and other material phenomena (e.g., hydrogen-enhanced decohesion and shock-induced phase changes) with the intention of understanding corrosion and subsequent failure processes and guiding the design of new protective coatings. This work examines corrosion and/or protection of materials ( i.e., Fe, Ni, W) with important applications: structural steel, gun tubes, high-pressure oil recovery vessels, jet engine turbine blades, and fusion reactor walls. We use DFT to model the pressure-induced, bcc-to-hcp phase transformation in Fe, in which a new low energy pathway is predicted exhibiting nonadiabatic behavior coupling magnetic and structural changes. Protection of steel is addressed in two aspects: interfacial adhesion of protective coatings and assessment of corrosion resistance provided by a surface alloy. First, the current chrome-coated steel system is examined where extremely strong adhesion is predicted at the Cr/Fe interface originating in strong spin correlations. A ceramic coating, SiC, is considered as a possible replacement for Cr. Strong adhesion is predicted, especially for C-Fe interfacial bonds. To assess corrosion resistance, we model ingress of two common corrosive elements, H and C, into two Fe alloys, FeAl and Fe3Si. Adsorption and absorption thermodynamics and kinetics, as well as bulk dissolution and diffusion are calculated in order to determine whether these two alloys can inhibit uptake of H and C. Relative to pure Fe, dissolved H and C are less stable in the alloys, as the dissolution enthalpy is predicted to be more endothermic. Overall, the energy barriers and rate constants for adsorbed H/C diffusing into Fe3Si subsurface layers suggests that alloying Fe with Si can be an effective means to limit uptake of these elements into steel. Spallation of protective layers on jet engine turbine blades is a problem that arises during thermal cycling. An alternative thermal barrier coating system involving MoSi2 is considered and calculations predict strong adhesion at the MoSi2/Ni interface. The interfacial bonding structure reveals a mixture of metallic and covalent cross-interface bonds. The adhesion energy is similar across all three MoSi2 facets studied. Upon exposure to oxygen, this MoSi2 alloy will form a strongly adhered oxide scale, which in turn may strongly adhere the heat shield material (yttria-stabilized zirconia), thereby potentially extending the lifetime of the barrier coating. Lastly, the interaction of hydrogen isotopes (fusion fuel) with tungsten (a proposed fusion reactor wall material) is examined. Exothermic dissociative adsorption is predicted, along with endothermic absorption and dissolution. Surface-to-subsurface diffusion energy barriers for H incorporation into bulk W are large and the corresponding outward diffusion barriers are very small. In bulk W, deep energetic traps (trapping multiple H atoms) are predicted at vacancy defects. Thus, under high neutron fluxes that will produce vacancies in W, H are predicted to collect at these vacancies. In turn, locally high concentrations of H at such vacancies will enhance decohesion of bulk W, consistent with observed blistering under deuterium implantation. Limiting vacancy formation may be key to the survival of W as a fusion reactor wall material.

Johnson, Donald F.

130

Influence of temperature on corrosion rate and porosity of corrosion products of carbon steel in anoxic bentonite environment  

Energy Technology Data Exchange (ETDEWEB)

Highlights: •The corrosion rate is not significantly dependent on temperature. •Corrosion products at higher temperatures have different color. •Corrosion products at higher temperatures are more compact. •The change in corrosion products nature is reversible. -- Abstract: The study focuses on the porosity of layers of corrosion products and its impact on corrosion rate of carbon steel in moist bentonite. Measurements were performed in an aggressive Czech type of bentonite – Rokle B75 at temperatures of 90 and 40 °C. Aggressiveness of B75 bentonite consists in low content of chlorides. Presence of chlorides in pore solution allows formation of more protective magnetite. The evaluation was made by electrochemical techniques (red/ox potential, open circuit potential, linear polarization resistance, impedance spectroscopy) and resistometric sensor measurements. The result imply that the higher the temperature the more compact is the layer of corrosion products that slightly decelerates corrosion rate compared to the state at 40 °C. The state of corrosion products at both temperatures is reversible.

Stoulil, J., E-mail: jan.stoulil@vscht.cz [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague (Czech Republic); Ka?ok, J.; Kou?il, M. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague (Czech Republic); Parschová, H. [Department of Power Engineering, Institute of Chemical Technology, Prague (Czech Republic); Novák, P. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague (Czech Republic)

2013-11-15

131

Principles and criteria for the evaluation of the corrosivity of atmospheric environments on steel structures  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents the environmental impact on steel structures and the corrosivity of atmospheric environments. It defines the principles and criteria for the evaluation of atmospheric-corrosivity classes, according to European standard, which were introduced in the new technical national regulations in the field of corrosion protection of steel structures. It shows the equivalence between the new corrosivity classes and the old aggressivity classes according to Romanian standard, still in force. The examples of typical environments corresponding to the corrosivity classes are also presented.

Ioan PEPENAR

2013-12-01

132

Corrosion protection and control using nanomaterials  

CERN Document Server

This book covers the use of nanomaterials to prevent corrosion. The first section deals with the fundamentals of corrosion prevention using nanomaterials. Part two includes a series of case studies and applications of nanomaterials for corrosion control.$bCorrosion is an expensive and potentially dangerous problem in many industries. The potential application of different nanostructured materials in corrosion protection, prevention and control is a subject of increasing interest. Corrosion protection and control using nanomaterials explores the potential use of nanotechnology in corrosion control. The book is divided into two parts. Part one looks at the fundamentals of corrosion behaviour and the manufacture of nanocrystalline materials. Chapters discuss the impact of nanotechnology in reducing corrosion cost, and investigate the influence of various factors including thermodynamics, kinetics and grain size on the corrosion behaviour of nanocrystalline materials. There are also chapters on electrodeposition ...

Cook, R

2012-01-01

133

Alternating Current Corrosion of Carbon Steel  

OpenAIRE

The objective was to investigate if the established theory concerning corrosion calculations and electrochemical behavior of carbon is valid when steel is exposed to AC in an electrolyte consisting of 3,5 wt% NaCl and distilled water. The experimental work was divided in two main parts. The first part concerned corrosion testing, including weight loss measurements in stagnant conditions in combination with linear polarization resistance experiments. AC-current densities investigated was 0-, 5...

Belland, Eirik

2011-01-01

134

Corrosion Protection of Electrically Conductive Surfaces  

OpenAIRE

The basic function of the electrically conductive surface of electrical contacts is electrical conduction. The electrical conductivity of contact materials can be largely reduced by corrosion and in order to avoid corrosion, protective coatings must be used. Another phenomenon that leads to increasing contact resistance is fretting corrosion. Fretting corrosion is the degradation mechanism of surface material, which causes increasing contact resistance. Fretting corrosion occurs when there is...

Jian Song; Liangliang Wang; Andre Zibart; Christian Koch

2012-01-01

135

Corrosion Behavior of Low Alloy Steels Containing Manganese in Mixed Chloride Sulfate Solution  

Science.gov (United States)

The corrosion resistance of the low alloy steels was improved by the addition of Mn up to 2.0 wt pct due to grain refinement and the formation of a protective rust layer. On the other hand, the addition of 5.0 wt pct manganese decreased the corrosion resistance of low alloy steel due to the microstructural changes that hinder the formation of the protective rust layer.

Nam, Nguyen Dang; Kim, Min Jun; Kim, Jung Gu

2014-02-01

136

Polyaspartic acid as a green corrosion inhibitor for carbon steel  

Energy Technology Data Exchange (ETDEWEB)

The inhibitor effect of the environmentally friendly corrosion inhibitor polyaspartic acid (PASP) on the corrosion of carbon steel in 0.5 M H{sub 2}SO{sub 4} was investigated by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). Polarization curve results clearly reveal the fact that PASP is a good anode-type inhibitor. EIS results confirm its corrosion inhibition ability. The inhibition efficiency increases with increasing PASP concentration, and the maximum inhibition efficiency was 80.33% at 10 C. SEM reveals that a protective film forms on the surface of the inhibited sample. The adsorption of this inhibitor is found to follow the Freundlich adsorption isotherm. A mechanism is proposed to explain the inhibitory action of the corrosion inhibitor. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Cui, R. [Department of Chemistry, Hebei Normal University, Shijiazhuang 050016 (China); Department of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu 215500 (China); Gu, N.; Li, C. [Department of Chemistry, Hebei Normal University, Shijiazhuang 050016 (China)

2011-04-15

137

Corrosion of austenitic steel in leakage lithium  

International Nuclear Information System (INIS)

High-temperature lithium, which is used as the neutron source in the International Fusion Material Irradiation Facility, reacts with oxygen, nitrogen, and moisture in the atmosphere. We estimated which lithium compounds might be stable under environmental conditions by using chemical equilibrium calculations, then performed austenitic stainless steel corrosion tests with the selected lithium compounds. The lithium compounds (reagents) and a steel specimen were heated to 1120 K in an Al2O3 Tammann crucible. After the test, the steel specimen was cleaned with alcohol and water and then weighed and metallurgically examined. We found that the steel was significantly corroded in Li3N, LiOH, and Li2O2 environments. Because Li2O2 is not stable according to the chemical equilibrium calculations, corrosion by Li3N and LiOH needs to be considered in high-temperature lithium applications

138

Corrosion of Steel in Concrete – Thermodynamical Aspects  

DEFF Research Database (Denmark)

The present understanding of selected corrosion phenomena in reinforced concrete is reviewed. Special emphasis is given to chloride induced corrosion. There is a general acceptance of the basic corrosion mechanism for steel in concrete. However different anodic reactions governing the subsequent formation and composition of corrosion products have been proposed. Suggested reactions, except half-cell reactions, are verified or rejected based on their Gibbs free energy, while the electrode potential is calculated for half-cell reactions. Corrosion products postulated to form are related to observations. A thermodynamically possible reaction mechanism for the formation of green rust in the presence of chlorides is proposed. Initial verification of the suggested mechanism is given based on experimental data from the literature and own observations.

Küter, Andre; MØller, Per

2004-01-01

139

Metronidazole: A Corrosion Inhibitor for Mild Steel in Aqueous Environment  

Scientific Electronic Library Online (English)

Full Text Available The inhibition efficiency (IE) of metronidazole (MZ)-Zn(II) system in controlling corrosion of mild steel in aqueous solution containing 60 ppm of Cl- ion has been evaluated by weight loss method. Weight loss study reveals that the formulation consisting of 140 ppm of MZ and 50 ppm of Zn(II) has 84% [...] inhibition efficiency in controlling corrosion of mild steel immersed in aqueous solution containing 60 ppm of Cl- ion. Polarization study reveals that this system as a mixed type of inhibitor controlling the cathodic and anodic reaction to an equal extent. AC impedance reveals that a protective film is formed on the metal surface. The FTIR spectra revealed that the protective film consists of Fe(II)-MZ complex.

S.M., Megalai; Y. P., Manjula; K.N., Manonmani; N., Kavitha; N., Baby.

2012-11-01

140

Statistical approach to underground corrosion of carbon steel pipeline  

International Nuclear Information System (INIS)

Field corrosion studies were performed on polyethylene (PE) coated carbon steel gas transmission pipeline buried in Korea. Chemical and biochemical analysis of the soil adjacent to coating defects of pipes were performed at both field and laboratory. Correlation between the maximum corrosion depth and environmental factors was evaluated by applying statistical methods. The factors controlling corrosion were considered by linear regression analysis, principal component analysis (PCA) and multiple regression analysis. The corrosion site had a strongly positive correlation with chemical factors such as low pH and high levels of chloride, and anaerobic nature of soil that promoted the growth of sulfate-reducing bacteria (SRB), characterized by low level of soil resistivity and reduction-oxidation potential and finally on pipe-to-soil potential. it was proved that the statistical approach described results of field and laboratory works satisfactorily. Finally, the prediction equation for the maximum corrosion depth of carbon steel in soil environment is presented. It is important that the chemical, biochemical and cathodic protection (CP) effects should be considered together for the precise prediction of corrosion behavior in soil environments

141

Corrosion behaviour of steels under neutral-oxygen water conditions  

International Nuclear Information System (INIS)

Results of different investigation stages carried on with the authors into the efficiency of neutral-oxygen aqueous conditions and confirmed positive effect of oxygen dissolved in coolant on increase of corrosion resistance of 1Kh18N10T steel and st. 20 are systematized and generalized. Comparison of protective capability of oxide films on st. 20 under conditions of atomic power equipment outage was performed

142

Corrosion of martensitic and ferritic steels in nuclear power plants  

International Nuclear Information System (INIS)

In nuclear reactor operation martensite or ferritic corrosion resistant steels come in contact with solutions used for desactivation prior to dismantling, repairs, etc. The most frequent type of corrosion is stress corrosion cracking. For achieving good corrosion resistance material heating should be avoided in mechanical treatment. Low-resistance corrosion centres may also result from the penetration of common steel particles, eg., in grinding. The corrosion resistance test can be effected by placing filter paper soaked with the said solution on the steel surface. Corrosion centres will be evident by their blue colouring after 10 minutes. (J.B.)

143

Electrochemical study of corrosion inhibition of stainless steel in phosphoric medium  

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-07-01

144

Improvement Corrosion Resistance of Low Carbon Steel by Using Natural Corrosion Inhibitor  

Directory of Open Access Journals (Sweden)

Full Text Available Carbon steel, the most widely used engineering material, despite its relatively limited corrosion resistance used in large tonnages in marine applications, nuclear powered transportation, chemical processing , petroleum production and refining, pipelines, mining, construction and metal-processing equipment. The main objective of the present work involved the study of the inhibiting properties of natural product as Spearmint plant extract as a safety and an environmentally friendly corrosion inhibitor for low carbon steel in (3.5% NaCl solution. Results showed when the immersion model in (3.5% NaCl solution that contains the inhibitor with concentration of (15% in volume, it's getting a decrease in lost weight , indicating a layer of adequate oxide on the surface of the steel, indicating that the amount of loss weight decrease with increasing concentration of inhibitor and this shows the damper on his ability to form a protective layer

Shaymaa Abbas Abdulsada

2013-06-01

145

Internal corrosion of carbon steel piping in hot aquifers service  

OpenAIRE

Internal corrosion of carbon steel pipelines is a major problem encountered in water service. In terms of prediction of the remaining lifetime for water pipelines based on the corrosion allowance, the three main approaches are corrosion modelling, corrosion inhibitor availability, and corrosion monitoring. In this study we used two theoretical corrosion models, CASSANDRA and NORSOK M-506 of quite different origin in order to predict uniform corrosivity of hot aquifers in eight different...

Simi?i? Miloš V.; Govedarica Dragan D.

2011-01-01

146

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

OpenAIRE

Investigations were carried out to study critically the corrosion behaviour and Stress Corrosion Cracking (SCC) of low and medium carbon steels in cassava and cocoa extracts by weight loss measurement and constant extension to fracture method respectively. The results obtained showed that medium carbon steel is more susceptible to corrosion than low carbon steel in both media. SCC is also more in medium carbon steel than low carbon steel in the two media under study. These deductions are due ...

Afolabi, Ayo Samuel

2007-01-01

147

Corrosion Behavior of Copper-Steel Particulate Composite  

OpenAIRE

This work was conducted to study the corrosion behavior of the steel particle reinforced copper matrix composites, under different conditions; namely heat treatment, concentration of corrosion media, and different weight percent of steel particles.The density, corrosion rate, micro-structure, and Vickers micro-hardness, were investigated. The results showed that composites with limited steel particle contents can be used. The microstructure of the composites showed severe corrosion of the ste...

Al-haidary, J. T.; Emad Al-Hassani; Areef, Sheelan R.

2011-01-01

148

Reinforcement steel corrosion in passive state and by carbonation: Consideration of galvanic currents and interface steel - concrete defaults  

International Nuclear Information System (INIS)

This thesis aims to study the durability of nuclear waste deep storage structures. The work carried out is essentially an experimental study, and focuses on the corrosion of steel in the passive state with aerated or non-aerated conditions on the one hand, and the corrosion of steel in carbonated concrete during the propagation phase on the other hand. Indeed, the pore solution of concrete in contact with the metal is alkaline (pH between 12 and 13). Under these conditions, steel reinforced concrete remains passive by forming a stable and protective oxide layer (corrosion of steel in the passive state). This passive layer limits the steel corrosion rate at very low values (negligible on a short life time) but not null. For the nuclear waste storage structures due to a very long life time (up to several hundred years), this low corrosion rate can become a risk. Therefore, it is necessary to study the evolution of the oxide layer growth over time. The objectives of the thesis are to study the influence of the steel-concrete interface quality on reinforcement corrosion in passive and active state, and the possible occurrence of galvanic corrosion currents between different reinforcement steel areas. (author)

149

The behaviour of praseodymium 4-hydroxycinnamate as an inhibitor for carbon dioxide corrosion and oxygen corrosion of steel in NaCl solutions  

International Nuclear Information System (INIS)

Highlights: •Praseodymium 4-hydroxycinnamate (Pr(4OHCin)3) highly effective corrosion inhibitor. •Mechanism of inhibition different in CO2-saturated solutions compared to aerated system. •In natural aerated solutions a continuous protective film forms on the steel surface. •In CO2-saturated solutions inhibiting deposits form at active corrosion sites. -- Abstract: Praseodymium 4-hydroxycinnamate (Pr(4OHCin)3) was investigated as a novel corrosion inhibitor for steel in NaCl solutions, and found to be effective at inhibiting corrosion in both CO2-containing and naturally-aerated systems. Surface analysis results suggest that the corrosion inhibition ability of Pr(4OHCin)3 in the naturally-aerated corrosion system could be attributed to the formation of a continuous protective film. For the CO2-containing system, the corrosion inhibition efficiency of Pr(4OHCin)3 was predominantly because of formation of protective inhibiting deposits at the active electrochemical corrosion sites, in addition to a thinner surface film deposit

150

Investigation of Carbon steel corrosion in water base drilling mud  

OpenAIRE

Carbon steel, the most widely used engineering material, accounts for approximately 85%, of the annual steel production worldwide. Despite its relatively limited corrosion resistance, carbon steel is used in large tonnages in marine applications, nuclear power and fossil fuel power plants, transportation, chemical processing, petroleum production and refining, pipelines, mining, construction and metal-processing equipment. This paper Investigate Carbon steel corrosion in water. The corrosion ...

Fadhil Sarhan Kadhim

2011-01-01

151

Corrosion and protection of aluminum alloys in seawater  

Energy Technology Data Exchange (ETDEWEB)

The paper deals with pitting and uniform corrosion and effectiveness of cathodic protection in reducing these corrosion forms. In stagnant waters or presence of low flow rates, pitting may occur. However, pitting corrosion, driven by the Fe-rich cathodic intermetallic compounds, is often of superficial nature. The pits tend to passivate as a result of etching or passivation of the intermetallics with time. Cathodic protection is an effective way of preventing pitting. It also requires low current densities since the cathodic area, defined by the Fe-rich intermetallics, is small in contrast to steel, which is uniformly accessible to the cathodic reaction. Although thermodynamic calculations suggest possible instability of the oxide in slightly alkaline solutions, such as seawater, protective nature of the oxide in practice is attributed to the presence of alloying elements such as Mg and Mn. Thus, the passivity of both the aluminum matrix alloy (the anode) and the intermetallics (cathodes) have to be considered in evaluating the corrosion and protection of aluminum alloys. With increasing flow rate, the possibility of pitting corrosion reduces with increase in the rate of uniform corrosion, which is controlled by the flow dependent chemical dissolution of the oxide. Cathodic protection does not stop this phenomenon, and coatings have to be used. (authors)

Nisancioglu Kemal [Department of Materials Technology, Norwegian University of Science and Technology, N-7491 Trondheim (Norway)

2004-07-01

152

Corrosion performance of martensitic stainless steel seamless pipe for linepipe application  

Energy Technology Data Exchange (ETDEWEB)

The corrosion performance of two types of weldable martensitic stainless steel seamless pipe for pipeline application is investigated. 11Cr steel pipe developed for sweet environment gives better resistance to CO{sub 2} corrosion than the 13Cr martensitic stainless steel for OCTG. 12Cr steel pipe developed for light sour environment shows good SSC resistance in a mild sour environment and superior CO{sub 2} corrosion resistance at high temperature and high CO{sub 2} partial pressure condition. The suitable condition for the 11Cr steel pipe and the 12Cr steel pipe in sweet environment, and the critical pH and H{sub 2}S partial pressure for the 12Cr steel pipe welded joint in sour environment are clarified. Both welded joints have superior resistance to hydrogen embrittlement under the cathodic protection condition in sea water.

Kimura, Mitsuo; Miyata, Yukio; Toyooka, Takaaki; Murase, Fumio [Kawasaki Steel Corp., Handa, Aichi (Japan)

1999-11-01

153

Corrosion of two kinds of cast steels containing chromium in hot concentrated alkaline  

Directory of Open Access Journals (Sweden)

Full Text Available A typical hot concentrated alkaline corrosion environment exists in alumina metallurgical industry, so that steel materials with outstanding alkaline corrosion resistance are strongly demanded for its processing equipment. In this paper, the corrosion resistance of two kinds of martensitic cast steels containing chromium in static 303g/L NaOH alkaline solution at 85? was studied through polarization and potential-time curves, corrosion weight loss and corrosion morphology analysis. Experimental results showed that protection effect by passive film of cast steel containing Cr was temporary. The low carbon steel without Cr content also exhibited chemical passivity in the same solution. The corrosion mode of the tested Cr-containing cast steel was composed of active dissolving corrosion and caustic embrittlement cracking. Dissolving corrosion was the primary mechanism for the induced weight loss, while severe caustic embrittlement cracking was secondary. With the increase of chromium content in the cast steel, the tendency of the caustic embrittlement cracking decreased, while the active dissolving corrosion increased.

LI Wei

2007-02-01

154

Point corrosion in steel 17 247  

International Nuclear Information System (INIS)

Susceptibility to point and intergranular corrosion was studied for titanium-stabilized steel CSN 17 247. Specimens were used from two melts featuring different surface finish, placed in three different corrosion media, viz.: 10% iron chloride solution, a solution of copper sulfate, sulfuric acid and distilled water with an addition of copper dust, and a boiling solution of 65% nitric acid. The specimens did not show susceptibility to intergranular corrosion in the sulfuric acid medium. In the boiling nitric acid, the melt with a higher titanium level and a coarser grain showed a lower corrosion rate than that with a lower titanium level, finer grain and the presence of delte-ferrite in the structure. An intensive course of point corrosion was found in the iron chloride medium. As for working, the lowest corrosion rate was found for conventional metal cutting treated surfaces, a higher rate for electrolytically polished surfaces. The highest rate of corrosion was observed for cast grit blasted surfaces. (Z.M.). 3 tabs., 8 refs

155

Development of ion-plated aluminide diffusion coatings for thermal cyclic oxidation and hot corrosion protection of a nickel-based superalloy and a stainless steel  

Science.gov (United States)

This project was carried out at the University of Toronto and Cametoid Ltd of Whitby, Ontario. Ohno continuous casting; a novel net shape casting technique, was used to generate, Al-Y, Al-Ce, Al-La, and Al-Si-Y, in form of 1.6 to 1.7 mm diameter alloy wires. These alloy wires exhibited suitable properties for use as feed materials to an Ion Vapor Deposition facility. The deposition parameters were optimized to provide coatings with a compact and cohesive columnar structure with reduced porosity and diffusion barriers that were essential to ensure the success of the diffusion process in the subsequent stage. Solid-state diffusion heat treatment processes were developed in order to form the stable aluminide phases, AlNi and FeAl, on IN738 and S310 substrates, respectively. Experiments simulating the coating service conditions and environments encountered during the prospective aerospace and fuel cell applications were conducted to evaluate the performance of each aluminide coating developed during this study. Thermal cyclic oxidation and molten sulfate corrosion studies were performed on coated IN738 pins at 1050°C and 900°C, respectively, simulating the service environment of turbine engine blades and other hot section components. Molten carbonate corrosion behavior was investigated for coated S310 coupons that were immersed in, or covered with a thin film of molten carbonate, at 650°C, in air plus 30%CO2, to simulate the operating conditions of the cathode-side separator plates of molten carbonate fuel cells. The behavior of the reactive elements, yttrium, cerium, lanthanum, and silicon in enhancing the adhesion of the protective aluminum oxide scale was determined by weight variation experiments, structural examination and compositional analysis. The influence of the base material elements, nickel, chromium, and iron, on the formation of protective oxides was investigated. All coatings were found to provide significant improvement for thermal cyclic oxidation and hot corrosion protection. For protection of IN738, Al-La coatings provided the greatest protection during oxidative thermal cycling, whereas Al-Ce coatings were found to be the most effective for protection against corrosive molten sulfate environments in aerospace applications. For protection of S310 against the corrosive environments of molten carbonate fuel cells, the effectiveness of the aluminide coatings were in the sequence, from the most to the least effective, Al-La, Al-Ce, Al-Y, and Al-Si-Y Mechanisms for Lanthanum and cerium protective behavior in high temperature aluminide diffusion coatings were suggested from the results of this study combined with literature information.

Elsawy, Abdel Raouf

156

Corrosion Properties for Hot-dip Aluminized Steel and 304 Stainless Steel  

International Nuclear Information System (INIS)

This paper dealt with the corrosion properties of hot-dip aluminized steel and 304 type stainless steel in various corrosion environments. Pitting and crevice corrosion rates of hot-dip aluminized steel were larger than those of 304 type stainless steel, but corrosion mode of the former was general corrosion and its mode of the latter was localized corrosion. By immersion test in 3.5% NaCl solution, also, corrosion rate of hot-dip aluminized steel was faster than that of 304 type stainless steel. In anodic polarization test, corrosion potential of 304 stainless steel was noble than that of hot-dip aluminized steel and showed better passivation behavior

157

49 CFR 192.461 - External corrosion control: Protective coating.  

Science.gov (United States)

...2010-10-01 2010-10-01 false External corrosion control: Protective coating...for Corrosion Control § 192.461 External corrosion control: Protective coating. (a) Each external protective coating, whether...

2010-10-01

158

Phenomenological investigation of the influence of Cathodic protection on corrosion fatigue crack propagation behaviour, in a BS 4360 50D type structural steel and associated weldment microstructures, in a marine environment.  

OpenAIRE

The influence of Cathodic Protection potential upon corrosion fatigue crack propagation rates in a medium7strength ferritic-pearlitic structural steel (ES 4360 grade 50D) and associated weldment microstructures in simulated sea-water was studied and the results were presented in bi-modal da/dN vs AK curves. Above transition propagation rate data was satisfactorily described by the Paris relationship da/dN = C. AKm and a relationship of the formin = Aln C+D between Paris e...

Thompson, J. W. C.

1984-01-01

159

Pitting corrosion detection in stainless steels using ultrasounds  

International Nuclear Information System (INIS)

Passive metallic systems are able to develop in a spontaneous way a protective layer on the metallic surface that offers excellent corrosion resistance since really in a physical barrier for the reaction with the environment. However, some factors can break locally this layer, promoting one of the most insidious attack, pitting corrosion, which produces local chemical conditions that favouring the corrosive process causing defects in the material, as externals and internals ones, with a random distribution on the metal surface. In this work, ultrasounds non destructive technique has been employed using as variable the maximum amplitude of the back wall echo in order to detect this type of attack. The material employed is an austenitic stainless steel AISI 304, wherein appear several defectology distributions as superficial such as depths simulating pits. (Author)

160

Corrosion behavior of low-alloy steel in the presence of Desulfotomaculum sp  

International Nuclear Information System (INIS)

The objective of this study was to determine the effect of sulfate-reducing Desulfotomaculum sp. bacteria isolated from a crude oil field on the corrosion of low-alloy steel. The corrosion rate and mechanism were determined with the use of Tafel slopes, mass loss method and electrochemical impedance spectroscopy (EIS). The formation of the biofilm and the corrosion products on the steel surface was determined with scanning electron microscopy (SEM) micrographs and energy dispersive X-ray spectra (EDS) analysis. It was observed from the Tafel plots that the corrosion potential exhibited a cathodic shift that verifies an increase in the corrosion rates. The semicircles tended to open at lower frequencies in the Nyquist plots which indicates the rupture of the protective film. The corrosion current density reached its maximum value at the 14th hour after the inoculation and decreased afterwards. This was attributed to the accumulation of corrosion products on the surface.

161

Corrosion-resistant analogue of Hadfield steel  

International Nuclear Information System (INIS)

The concept of alloying austenitic steels with carbon + nitrogen is used for the development of a corrosion-resistant austenitic CrMn steel having an impact wear resistance close to that of the Hadfield steel. A higher stabilization of the austenitic phase by C + N, as compared to carbon or nitrogen alone, is substantiated by ab initio calculation of the electron structure, measurements of the concentration of free electrons and calculations of the phase equilibrium. Based on these results, the compositions (mass%) Cr18Mn18C0.34N0.61 and Cr18Mn18C0.49N0.58 were melted and tested along with Hadfield steel Mn12C1.2. Mechanical tests have shown that, as compared to the Hadfield steel, the experimental steels possess a higher strength, plasticity, hardness and the same resistance to impact wear. TEM studies of the surface layer after impact treatment revealed a mixture of the amorphous phase, nanocrystals and fine-twinned austenite. At the same time, using Moessbauer spectroscopy of conversion electrons, the ferromagnetic ordering was found in the surface layer of up to 10 ?m in depth, which is the sign of the strain-induced martensitic phase. The hypothesis of a transition from the low-spin to the high-spin state of the iron atoms within the thin twins in austenite was proposed in order to interpret the discrepancy between TEM and Moessbauer studies. Potentiodynamic measurements and immersion tests show that the CrMnCN steels possess a significantly higher pitting potensess a significantly higher pitting potential and resistance to general corrosion in comparison with Hadfield steel

162

Corrosion-resistant analogue of Hadfield steel  

Energy Technology Data Exchange (ETDEWEB)

The concept of alloying austenitic steels with carbon + nitrogen is used for the development of a corrosion-resistant austenitic CrMn steel having an impact wear resistance close to that of the Hadfield steel. A higher stabilization of the austenitic phase by C + N, as compared to carbon or nitrogen alone, is substantiated by ab initio calculation of the electron structure, measurements of the concentration of free electrons and calculations of the phase equilibrium. Based on these results, the compositions (mass%) Cr18Mn18C0.34N0.61 and Cr18Mn18C0.49N0.58 were melted and tested along with Hadfield steel Mn12C1.2. Mechanical tests have shown that, as compared to the Hadfield steel, the experimental steels possess a higher strength, plasticity, hardness and the same resistance to impact wear. TEM studies of the surface layer after impact treatment revealed a mixture of the amorphous phase, nanocrystals and fine-twinned austenite. At the same time, using Moessbauer spectroscopy of conversion electrons, the ferromagnetic ordering was found in the surface layer of up to 10 {mu}m in depth, which is the sign of the strain-induced martensitic phase. The hypothesis of a transition from the low-spin to the high-spin state of the iron atoms within the thin twins in austenite was proposed in order to interpret the discrepancy between TEM and Moessbauer studies. Potentiodynamic measurements and immersion tests show that the CrMnCN steels possess a significantly higher pitting potential and resistance to general corrosion in comparison with Hadfield steel.

Gavriljuk, V.G. [G.V. Kurdyumov Institute for Metal Physics, UA-03680 Kiev (Ukraine)]. E-mail: gavr@imp.kiev.ua; Tyshchenko, A.I. [G.V. Kurdyumov Institute for Metal Physics, UA-03680 Kiev (Ukraine); Razumov, O.N. [G.V. Kurdyumov Institute for Metal Physics, UA-03680 Kiev (Ukraine); Petrov, Yu.N. [G.V. Kurdyumov Institute for Metal Physics, UA-03680 Kiev (Ukraine); Shanina, B.D. [Ruhr University Bochum, D-44780 Bochum (Germany); Berns, H. [Institute for Semiconductor Physics, 03028 Kiev (Ukraine)

2006-03-25

163

Influence of alloying elements on the corrosion properties of shape memory stainless steels  

International Nuclear Information System (INIS)

Highlights: ? The corrosion properties of three Fe–Mn–Si–Cr–Ni–(Co) shape-memory stainless steels (SMSSs) were compared with those of a type 304 (SS 304) austenitic stainless steel. ? A considerably high Si content (about 40 at%) is present in the anodic passive films formed on SMSSs in 0.5 M H2SO4 solution. ? The high protectiveness of the anodic passive film formed on SMSSs in 0.5 M H2SO4 solution results from a protective film consisting of a (Fe, Cr)–mixed silicate. ? The SMSSs exhibited higher corrosion resistance than SS 304 in highly oxidizing environments. ? The SMSSs showed poor corrosion resistance in 3.5% NaCl solution compared to that of SS 304. - Abstract: The corrosion properties of three Fe–Mn–Si–Cr–Ni–(Co) shape memory stainless steels were studied based on X-ray photoelectron spectroscopy (XPS) analyses, immersion and polarization tests. The test results were compared with those of a type 304 austenitic stainless steel. The XPS analyses indicated substantial Si content in the anodic passive films formed on shape memory stainless steels in sulfuric acid solution and that the high protectiveness of these films results from a protective film consisting of a (iron, chromium)–mixed silicate. The corrosion rate of the shape memory stainless steels in boiling nitric acid solution was lower than that of austenitic stainless steel. The high silicon content was found to play an importn important role in the corrosion behavior of these shape memory alloys in highly oxidizing environments. Due to their high manganese content, the shape memory stainless steels showed poor corrosion behavior in 3.5% sodium chloride solution when compared with austenitic stainless steel.

164

Corrosion of the steel under thermal insulation - causes and means of prevention  

International Nuclear Information System (INIS)

Corrosion problems of carbon and austenitic stainless steels under thermal insulation is discussed. Attention is paid to the high aggressiveness of environment especially with intermittent cycling down into hot water range due to frequent shutdowns. The availability of effective coatings protecting steel under thermal insulation is indicated, such as, epoxyphenolic, epoxy-novolac, inorganic zinc and aluminium aluminizing. (author)

165

Atmospheric corrosion of mild steel in Oman  

Energy Technology Data Exchange (ETDEWEB)

A systematic study has been made of the initial corrosion products which form on mild steel capons exposed near the coastal region of Oman and at some industrial areas. The phases and compositions of the products formed at different periods of exposure were examined by using Moessbauer spectroscopy (295 and 78 K) and X-ray diffraction (XRD) techniques. The results show that lepidocorcite and maghemite are early corrosion products and goethite starts to form after 2 months of metal exposure to the atmosphere. Akaganeite is an early corrosion product but it forms in marine environments only, which reflects the role of chlorine effect in the atmosphere. The 12 months coupons showed the presence of goethite, lepidocorcite and maghemite, but no akaganeite being seen in the products of one of the studied areas.

Gismelseed, Abbasher, E-mail: abbasher@squ.edu.om; Al-Harthi, S. H.; Elzain, M.; Al-Rawas, A. D.; Yousif, A.; Al-Saadi, S.; Al-Omari, I.; Widatallah, H.; Bouziane, K. [College of Science, Department of Physics (Oman)

2006-01-15

166

Atmospheric corrosion of mild steel in Oman  

International Nuclear Information System (INIS)

A systematic study has been made of the initial corrosion products which form on mild steel capons exposed near the coastal region of Oman and at some industrial areas. The phases and compositions of the products formed at different periods of exposure were examined by using Moessbauer spectroscopy (295 and 78 K) and X-ray diffraction (XRD) techniques. The results show that lepidocorcite and maghemite are early corrosion products and goethite starts to form after 2 months of metal exposure to the atmosphere. Akaganeite is an early corrosion product but it forms in marine environments only, which reflects the role of chlorine effect in the atmosphere. The 12 months coupons showed the presence of goethite, lepidocorcite and maghemite, but no akaganeite being seen in the products of one of the studied areas.

167

Stress corrosion cracking evaluation of precipitation-hardening stainless steel  

Science.gov (United States)

Accelerated test program results show which precipitation hardening stainless steels are resistant to stress corrosion cracking. In certain cases stress corrosion susceptibility was found to be associated with the process procedure.

Humphries, T. S.; Nelson, E. E.

1970-01-01

168

Corrosion inhibition of carbon steel by sodium metavanadate  

Directory of Open Access Journals (Sweden)

Full Text Available The inhibition efficiency of sodium metavanadate (SMV-adipic acid (AA system in controlling corrosion of carbon steel in an aqueous solution containing 60 ppm of Cl- has been evaluated by weight-loss method; 250 ppm of SMV exhibits inhibition efficiency of 56 %. Addition of adipic acid to SMV improves the inhibition efficiency of the system. The formulation consisting of 250 ppm of SMV and 250 ppm of adipic acid has inhibition efficiency of 98 %. A synergistic effect exists between SMV and adipic acid with the synergism parameters greater than 1. Mecha¬nistic aspects of corrosion inhibition have been studied by electrochemical methods like potentiodynamic polarization and electrochemical impedance spectroscopy. FTIR spectra reveal that the protective film consists of Fe2+-SMV complex and Fe2+-adipic acid complex. The protective film has been analyzed by fluorescence spectra, SEM and EDAX.

VIJAYA GOPAL SRIBHARATHY

2012-08-01

169

Assessing resistance to intergranular corrosion of corrosion resistant steels with balanced chemical composition  

International Nuclear Information System (INIS)

The resistance is discussed against intergranular corrosion of materials used for the manufacture of nuclear reactor components. Titanium or niobium stabilized steels with a low carbon content, nitrogen modified with a balanced chemical composition are used for aqueous media. The main types of damage are discussed, namely intergranular corrosion cracking, production defects, defects caused by corrosion fatigue. The dependence is derived on the chromium content of steel of the susceptibility to intergranular corrosion. The question is studied of the optimization of the chemical composition of steels for nuclear power. A control procedure is suggested for the manufacture of steels with suitable mechanical properties and good corrosion resistance. (J.C.)

170

Corrosion of steel in concrete in cooling water walls. Report part 3 - Corrosion of steel in water saturated concrete  

International Nuclear Information System (INIS)

It is a well known fact that for concrete structures exposed to water the splash zone exhibit the greatest risk for corrosion on the reinforcement. Chloride ions are enriched and the supply of oxygen is good. Below the water table reported corrosion damages are few. The threshold for chloride content is in most cases exceeded but the propagation rate is low due to slow diffusion rate of oxygen in water saturated concrete. Despite this, ongoing corrosion of reinforcement has been observed in cooling water systems at the Swedish nuclear power plants. The aim of this project has been to identify and qualitatively quantify the importance of different possible mechanisms involved in corrosion of reinforcement in water saturated concrete. This has been achieved by collecting experiences, literature survey, modelling, theoretical calculations, experimental investigations as well as field measurements. The investigations have resulted in several new findings. The following have been concluded: In water saturated concrete, without the existence of macro cells, the reinforcement corrodes in an active state but with a very low rate. This active corrosion proceeds independently of the chloride content of the concrete. The corrosion rate is low even with thin concrete cover and most probably even if the concrete has been leached. Nor does high velocity of the cooling water create serious attacks. Inspections have unveiled attacks of reinforcement corrosion in the splash zone, in walls externally exposed to air and in the vicinity to pumps. In the splash zone the attacks occur above the water level. The absence of a macro cell resulting in increased corrosion on parts below the water line is of subordinate importance and is judged being without practical influence. The corrosion takes place where the environmental conditions are optimal. The same is valid for walls externally exposed to air. The macro cell is of subordinate importance. In the vicinity of pumps, observed corrosion, is probably caused by galvanic corrosion as a consequence of incomplete cathodic protection of stainless steel surfaces within the pumps. Single rebar's being isolated from the rest of the reinforcement can be exposed to stray current corrosion if they are located close to a cathodically protected structure having a high demand for protective current. Concrete structures of greater extent can be exposed to stray current interference caused by high voltage direct current transmission lines located in the neighbourhood. Future installations of cathodic protection in extended culverts should not imply connection of separate parts to each other. The risk of alternating current corrosion is judged to be minimal. If it was not for the corrosion observed on reinforcement on the Oeland Bridge and in Gothenburg harbour, which until now has not been explained, corrosion should be possible to exclude in other positions than the splash zone, walls externally exposed to air and in the vicinity to unprotected structures of stainless steel

171

Corrosion Protection of Electrically Conductive Surfaces  

Directory of Open Access Journals (Sweden)

Full Text Available The basic function of the electrically conductive surface of electrical contacts is electrical conduction. The electrical conductivity of contact materials can be largely reduced by corrosion and in order to avoid corrosion, protective coatings must be used. Another phenomenon that leads to increasing contact resistance is fretting corrosion. Fretting corrosion is the degradation mechanism of surface material, which causes increasing contact resistance. Fretting corrosion occurs when there is a relative movement between electrical contacts with surfaces of ignoble metal. Avoiding fretting corrosion is therefore extremely challenging in electronic devices with pluggable electrical connections. Gold is one of the most commonly used noble plating materials for high performance electrical contacts because of its high corrosion resistance and its good and stable electrical behavior. The authors have investigated different ways to minimize the consumption of gold for electrical contacts and to improve the performance of gold plating. Other plating materials often used for corrosion protection of electrically conductive surfaces are tin, nickel, silver and palladium. This paper will deal with properties and new research results of different plating materials in addition to other means used for corrosion protection of electrically conductive surfaces and the testing of corrosion resistance of electrically conductive surfaces.

Jian Song

2012-11-01

172

Electrochemical Studies of Stainless Steel Corrosion in Peroxide Solutions  

OpenAIRE

Pollution control measures have resulted in replacement of chlorine by peroxide as bleaching chemical. Change of chemical affects corrosion aspects, the suitability of existing plant metallurgy and materials of construction of bleach plants. Accordingly long term immersion and electrochemical corrosion tests were conducted on stainless steel 304L, 316L, 2205 and 6% Mo and mild steel in peroxide solutions of pH 10. The materials were tested for uniform corrosion, pitting and crevice corrosion ...

Singh, Ajay K.; Vipin Chaudhary; Sharma, A.

2012-01-01

173

49 CFR 192.463 - External corrosion control: Cathodic protection.  

Science.gov (United States)

...Transportation 3 2010-10-01 2010-10-01 false External corrosion control: Cathodic protection. 192.463 Section...STANDARDS Requirements for Corrosion Control § 192.463 External corrosion control: Cathodic protection. (a)...

2010-10-01

174

Electrochemical protection of pointed metallic structures from atmospheric corrosion  

International Nuclear Information System (INIS)

Efficiency of electrochemical protection (ECP) of steel against atmospheric corrosion under thin electrolyte films is investigated. It is shown that the zone of ECP action is restricted by a low conductivity of moisture films, occurring on metals under natural conditions. A method of increasing ECP efficiency by means of using electroconducting coatings applied to standard paint and varnish coatings, is proposed. 6 refs., 2 figs

175

Variables affecting mixed oxidant corrosion of stainless steels in gasifiers  

International Nuclear Information System (INIS)

This paper is the final installment of EPRI's project on corrosion in syngas coolers of integrated coal gasification combined cycle plant. In previous papers we explored the effect of chloride species on mixed oxidant corrosion of stainless steels (CORROSION 97, paper 134) and iron aluminides (CORROSION 98, paper 185). It was found that the amount of chloride species in the gas and in deposits largely determined the rate of corrosion. Armed with this understanding the effect of a few common process variables is explored in this paper. It was found that corrosion rates decline at higher temperatures when chloride-enhanced mixed oxidant corrosion occurs at lower temperatures, but corrosion rates increase with temperature for pure sulfidation/oxidation, as may be expected. System pressure was generally of secondary importance, but again higher corrosion rates were generally experienced at elevated pressure, when chloride-enhanced corrosion was predominant, especially at lower temperatures. A simulated temperature excursion below the syngas dewpoint had similar effects, and also caused chloride enhanced corrosion in 310 stainless steel, which usually does not show this type of corrosion, except when exposed to aqueous corrosion during downtime. A pleasant surprise was the almost complete lack of corrosion when H2S and HCl levels were reduced to those expected downstream from gasifiers using in-bed desulfurization. It would appear that 12Cr steels may be adequatuld appear that 12Cr steels may be adequate here. This is being explored further. (orig.)

176

The corrosion of some stainless steels in a marine mud  

Energy Technology Data Exchange (ETDEWEB)

The report presents the results for three alloys: carbon steel, 316L stainless steel and a proprietary super duplex stainless steel (UNS S32760), exposed in a marine mud off the south coast of England for 5 years. Analysis of the mud showed it to be very aggressive using a corrosion index developed at the University of Manchester. Carbon steel showed a typical corrosion rate for microbial attack with pits up to 0.64mm deep. The 316L stainless steel had extensive broad, shallow attack with a few, deeper pits. The Z100 parent pipe and weldments showed no evidence of corrosion attack.

Francis, R.; Byrne, G. [Weir Materials and Foundries Park Works, Manchester (United Kingdom); Campbell, H.S. [Univ. of Surrey (United Kingdom). Dept. of Materials Science and Engineering

1999-11-01

177

Anti-Corrosive Effect of Tridax Procumbens – Zn2+ System Controlling the Corrosion of Carbon Steel  

Directory of Open Access Journals (Sweden)

Full Text Available The corrosion inhibition efficiency (IE of an aqueous extract Tridax Procumbens(TP in controlling the corrosion of carbon steel aqueous medium containing 60 ppm of chloride ions in absence and presence of Zn2+ has been studied by weight loss method. The formulation consisting of 1 ml of Tridax Procumbens extract and 150 ppm of Zn2+ offers 96% inhibition efficiency. The synergistic effect exists between Tridax Procumbens and Zn2+ system. Polarization study shows that the Tridax Procumbens – Zn2+ system function as a cathodic inhibitor. AC impedance spectra reveal that a protective film formed on the surface. The Adsorption equilibrium exhibited better fit to Langmuir isotherm than Freundlich isotherm. FTIR spectra reveal that the protective film consists of Fe2+ -Tridax Procumbens and Zn(OH2.

C. Kumar

2014-03-01

178

Corrosion inhibition in 2.0 M sulfuric acid solutions of high strength maraging steel by aminophenyl tetrazole as a corrosion inhibitor  

Energy Technology Data Exchange (ETDEWEB)

The corrosion of high strength maraging steel after varied immersion times in concentrated solution, 2.0 M, of sulfuric acid has been investigated. The work was also extended to study the effect of 5-(3-aminophenyl)-tetrazole (APTA) on the inhibition of the steel corrosion. The study has been carried out using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electron microscope (SEM) along with energy dispersive X-ray analyzer (EDX) investigations. EIS spectra showed that the corrosion and polarization resistances decrease with increasing the immersion time of the steel before measurement and increase in the presence of APTA and the increase of its concentration. Polarization data agreed with the EIS measurements and indicated that the increase of immersion time increases the corrosion of steel by increasing its corrosion current and corrosion rate and lowering its polarization resistance. On the other hand, the addition of APTA and the increase of its concentration minimized the corrosion of steel through decreasing the corrosion current and corrosion rate and increasing the polarization resistance at all exposure test periods. SEM and EDX investigations confirmed that the inhibition of the maraging steel in the 2.0 M H{sub 2}SO{sub 4} solutions is achieved via the adsorption of the APTA molecules onto the steel protecting its surface from being dissolved easily.

Sherif, El-Sayed M., E-mail: emsherif@gmail.com [Center of Excellence for Research in Engineering Materials (CEREM), Advanced Manufacturing Institute, King Saud University, PO. Box 800, Al-Riyadh 11421 (Saudi Arabia); National Research Centre (NRC), Electrochemistry and Corrosion Laboratory, Department of Physical Chemistry, National Research Centre (NRC), Dokki, 12622 Cairo (Egypt)

2014-02-15

179

Corrosion inhibition in 2.0 M sulfuric acid solutions of high strength maraging steel by aminophenyl tetrazole as a corrosion inhibitor  

Science.gov (United States)

The corrosion of high strength maraging steel after varied immersion times in concentrated solution, 2.0 M, of sulfuric acid has been investigated. The work was also extended to study the effect of 5-(3-aminophenyl)-tetrazole (APTA) on the inhibition of the steel corrosion. The study has been carried out using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electron microscope (SEM) along with energy dispersive X-ray analyzer (EDX) investigations. EIS spectra showed that the corrosion and polarization resistances decrease with increasing the immersion time of the steel before measurement and increase in the presence of APTA and the increase of its concentration. Polarization data agreed with the EIS measurements and indicated that the increase of immersion time increases the corrosion of steel by increasing its corrosion current and corrosion rate and lowering its polarization resistance. On the other hand, the addition of APTA and the increase of its concentration minimized the corrosion of steel through decreasing the corrosion current and corrosion rate and increasing the polarization resistance at all exposure test periods. SEM and EDX investigations confirmed that the inhibition of the maraging steel in the 2.0 M H2SO4 solutions is achieved via the adsorption of the APTA molecules onto the steel protecting its surface from being dissolved easily.

Sherif, El-Sayed M.

2014-02-01

180

Corrosion inhibition in 2.0 M sulfuric acid solutions of high strength maraging steel by aminophenyl tetrazole as a corrosion inhibitor  

International Nuclear Information System (INIS)

The corrosion of high strength maraging steel after varied immersion times in concentrated solution, 2.0 M, of sulfuric acid has been investigated. The work was also extended to study the effect of 5-(3-aminophenyl)-tetrazole (APTA) on the inhibition of the steel corrosion. The study has been carried out using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electron microscope (SEM) along with energy dispersive X-ray analyzer (EDX) investigations. EIS spectra showed that the corrosion and polarization resistances decrease with increasing the immersion time of the steel before measurement and increase in the presence of APTA and the increase of its concentration. Polarization data agreed with the EIS measurements and indicated that the increase of immersion time increases the corrosion of steel by increasing its corrosion current and corrosion rate and lowering its polarization resistance. On the other hand, the addition of APTA and the increase of its concentration minimized the corrosion of steel through decreasing the corrosion current and corrosion rate and increasing the polarization resistance at all exposure test periods. SEM and EDX investigations confirmed that the inhibition of the maraging steel in the 2.0 M H2SO4 solutions is achieved via the adsorption of the APTA molecules onto the steel protecting its surface from being dissolved easily.

181

Improvement of barrier properties of a hybrid sol-gel coating by incorporation of synthetic talc-like phyllosilicates for corrosion protection of a carbon steel  

OpenAIRE

Sol-gel coatings for corrosion protection of metals are a good alternative to toxic chromate treatments. The present work focussed on the incorporation of inorganic fillers in a sol-gel coating to improve the barrier properties of the film. Talc-like phyllosilicates obtained by hydrothermal synthesis at 160°C, 260°C and 350°C, called T160, T260 and T350 respectively, were selected as inorganic fillers. The synthetic materials showed talc lamellar structure but, in contrast with natural tal...

Joncoux-chabrol, Karine; Bonino, Jean-pierre; Gressier, Marie; Menu, Marie-joe?lle; Pe?be?re, Nadine

2012-01-01

182

Calculation of minimum cathodic protection potential of carbon steel in soil using cathodic polarization curve  

International Nuclear Information System (INIS)

Consideration is given to the simple method for calculating the minimal protective potential and corrosion rate of steel in soil using cathode curve and the value of free corrosion potential. The suggested electrochemical method for calculating corrosion rate at cathode polarization requires the minimal number of experimental data (cathode polarization curve and E cor value) and calculation procedure is very simple

183

Influence of burnishing on stress corrosion cracking susceptibility of duplex steel  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: of the current study was to investigate the usability of burnishing-inducted surface enhancement method for improve the stress corrosion cracking resistance of duplex stainless steel.Design/methodology/approach: The surface layers upon round in cross section specimens were performed through burnishing treatment. Corrosion tests were performed with the use of Slow Strain Rate Test technique in inert (glycerin and aggressive (boiling 35% MgCl2 solution environments.Findings: It was shown that burnishing treatment increases corrosion resistance of the steel. Stress corrosion cracking resistance depends on the magnitude of cold work at surface layers. High level of cold work decreases corrosion resistance.Research limitations/implications: This study does not indicate the optimum stress level and stress distribution in surface layers for the best corrosion resistance. It is necessary to continue the research to determine burnishing parameters for demanded properties of duplex steel surface layers.Practical implications: The burnishing treatment can significantly improve stress corrosion resistance of specified parts of chemical installations working in the contact with aggressive media. Such parts as valve parts or propeller shafts can be successfully protected against corrosion attack.Originality/value: Burnishing surface enhancement for constructional parts made of duplex stainless steels exposed to corrosive environments has not been reported in literature. Application of this technology can increase life-time of chemical installation devices and improve their reliability.

J. ?abanowski

2006-09-01

184

Stress Corrosion Cracking of Carbon Steel Weldments  

International Nuclear Information System (INIS)

An experiment was conducted to investigate the role of weld residual stress on stress corrosion cracking in welded carbon steel plates prototypic to those used for nuclear waste storage tanks. Carbon steel specimen plates were butt-joined with Gas Metal Arc Welding technique. Initial cracks (seed cracks) were machined across the weld and in the heat affected zone. These specimen plates were then submerged in a simulated high level radioactive waste chemistry environment. Stress corrosion cracking occurred in the as-welded plate but not in the stress-relieved duplicate. A detailed finite element analysis to simulate exactly the welding process was carried out, and the resulting temperature history was used to calculate the residual stress distribution in the plate for characterizing the observed stress corrosion cracking. It was shown that the cracking can be predicted for the through-thickness cracks perpendicular to the weld by comparing the experimental KISCC to the calculated stress intensity factors due to the welding residual stress. The predicted crack lengths agree reasonably well with the test data. The final crack lengths appear to be dependent on the details of welding and the sequence of machining the seed cracks, consistent with the prediction

185

Effect of debonded interfaces on corrosion of mild steel composites in supercritical CO2-saturated brines  

Energy Technology Data Exchange (ETDEWEB)

The geologic sequestration of CO{sub 2} is a proposed method to limit greenhouse gas emissions and has been the subject of many studies in the last decade. Wellbore systems achieve isolation of the storage reservoir through a combination of steel (generally carbon steel) and Portland cement. CO{sub 2} leakage along the steel-cement interface has the potential to accelerate corrosion. We conduct experiments to assess the corrosion risk at cement-steel interface under in situ wellbore conditions. Wellbore interfaces were simulated by assemblies constructed of J55 mild steel and Portland class G (Epoxy was used in this study to separate) cement and corrosion was investigated in supercritical CO{sub 2} saturated brines, (NaCl = 1 wt%) at T = 50 C, pCO{sub 2} = 1200 psi with interface gap size = 100 {micro}m and {infinity} (open surface). The experiments were carried out in a high-pressure, 1.8 L autoclave. The corrosion kinetics were measured employing electrochemical techniques including linear polarization resistance and electrochemical impedance spectroscopy techniques. The corrosion scales were analyzed using secondary electron microscopy, back scattering electron microscopy, energy dispersive spectroscopy and x-ray diffraction. Corrosion rates decreased as time with or without interface gap. In this case corrosion rates are controlled by scale protectivity through the interface gap. Scaled steel corrosion rates were two orders of magnitude less compared with fresh steel. The corrosion scale is pseudo crystalline at the open interface. Well-crystallized scale was observed at interface gap sizes 100 {micro}m. All corrosion scales were composed of iron carbonates.

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

2010-10-07

186

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

International Nuclear Information System (INIS)

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

187

Microbiological Corrosion in Low Carbon Steels  

Directory of Open Access Journals (Sweden)

Full Text Available The Microbiologically Induced Corrosion affects several industries, such as oil industry where it is estimated that 20% to 30% pipes failures are related with microorganism . The chemical reactions generate ions transfer, this validate the use of electrochemical techniques for its analysis. Coupons submerged in a nutritional medium with presence and absence of three different microorganisms during two periods, 48 hours and 28 days we restudied. Polarization resistance (Rp and Electrochemical Impedance Spectroscopy (EIS techniques we re applied to determine the corrosivity of the systems. The results show a greater corrosive effect of abiotic system, this indicates a microorganisms protection effect to the metal, opposite to the first hypothesis. This result was ratified observing surfaces coupons by using Scanning Electron Microscopy (SEM technique. A possible mechanism based on Evans – Tafel graph is proposed to explain inhibitor microorganism effect.

O. Medina–Custodio

2009-01-01

188

Atmospheric corrosion of galvanized steel in a marine environment  

International Nuclear Information System (INIS)

Atmospheric corrosion is the electrochemical process of metal deterioration from the action of atmospheric factors, both meteorological as well as chemical. Metals deteriorate due to their spontaneous oxidation when their surface is moistened with a film of condensed water, dew, fog or rain and this process leads to the formation of a protective film that acts as a physical barrier between the metal and the environment. However, this layer of corrosion can become a non protective film, due to a physical discharge or a partial dissolution of some soluble corrosion products of the material (galvanized steel) during rainfall or in condensed water on the material's surface. This process is known as metal runoff. In order to estimate the runoff process for galvanized steel and to study its behavior to atmospheric corrosion in a marine environment, samples of 10x10x0,6cm galvanized steel, with a coating thickness of 100 m Zn, were exposed in the city of Valparaiso, Region V, Chile. The atmospheric station is located at lat. 32AS and long. 71oW, classified according to ISO 9223 to 9226 as C2, S1 and P1, with a humidification time of 0.6 and chloride ion and sulfur dioxide content of 40.65 mgm-2day-1 and 7.18 mgm-2day-1, respectively. The deterioration of the galvanized steel was evaluated by weight loss measurements, determination of 'in situ' corrosion potential and morphology of the attack using scanning eleorphology of the attack using scanning electron microscopy (SEM). The composition of the corrosion products was determined by X-ray diffraction (XRD). The runoff solutions collected after the rainfall events were analyzed with different techniques to determine the content of Cl- ions, SO4-2 and dissolved solids, and pH and conductivity were measured as well. The concentration of Zn+2 is obtained by atomic adsorption spectroscopy. After four months of exposure of the test pieces preliminary results show that the potential for corrosion of the galvanized steel increased over time, which corroborates the formation of a protective film for zinc corrosion products, These were identified as zincite (ZnO) and simonkolleite (Zn5(OH)8Cl.H2O). The pH values from the runoff solutions from the rainfall events (first three events) are similar to the pH of the rainwater (white), while the conductivity and dissolved solids content of these solutions diminishes in relation to the exposure time. The chloride content also tends to decrease and stabilize over time, unlike the sulphate content that behaves randomly in relation to the amount of atmospheric SO2. The total amount of zinc lost as a soluble product increases over time and tends to stabilize

189

New Sol-gel Formulations to Increase the Barrier Effect of a Protective Coating Against the Corrosion and Wear of Galvanized Steel  

Scientific Electronic Library Online (English)

Full Text Available This study proposes a new pretreatment method that uses alkoxide precursors with a plasticizing agent; the purpose of this study is to improve the electrochemical and mechanical properties of a galvanized steel surface. Galvanized steel was covered with a hybrid film obtained from a sol that consist [...] ed of two alkoxide precursors, 3 - (trimethoxysilylpropyl) methacrylate (TMSM) and tetraethoxysilane (TEOS), with nitrate cerium in a concentration of 0.01 M and a polyethylene glycol (PEG) plasticizer. The hybrid coatings were obtained by dip-coating method with various concentrations of plasticizer (0, 20, 40 and 60 g.L-1). The hybrid films were analyzed by scanning electron microscopy (SEM), profilometry, contact angle measurements, a tribometer with the type-setting ball on the plate and electrochemical tests. The addition of the plasticizer into the hybrid films improves the corrosion resistance behavior compared to the sample without the plasticizer. The addition of 20 g.L-1 of plasticizer showed the best performance in the electrochemical tests. The mechanical behavior results indicated that higher PEG concentrations resulted in films with enhanced durability.

Sandra Raquel, Kunst; Henrique Ribeiro Piaggio, Cardoso; Lilian Vanessa Rossa, Beltrami; Claúdia Trindade, Oliveira; Tiago Lemes, Menezes; Jane Zoppas, Ferreira; Célia de Fraga, Malfatti.

2015-02-01

190

Corrosion behaviors of US steels in flowing lead-bismuth eutectic (LBE)  

International Nuclear Information System (INIS)

Corrosion tests of several US martensitic and austenitic steels were performed in a forced circulation lead-bismuth eutectic non-isothermal loop at the Institute of Physics and Power Engineering (IPPE), Russia. Tube and rod specimens of austenitic steels 316/316L, D-9, and martensitic steels HT-9, T-410 were inserted in the loop. Experiments were carried out simultaneously at 460 deg. C and 550 deg. C for 1000, 2000 and 3000 h. The flow velocity at the test sections was 1.9 m/s and the oxygen concentration in LBE was in the range of 0.03-0.05 wppm. The results showed that at 460 deg. C, all the test steels have satisfactory corrosion resistance: a thin protective oxide layer formed on the steel surfaces and no observable dissolution of steel components occurred. At 550 deg. C, rod specimens suffered rather severe local liquid metal corrosion and slot corrosion; while tube specimens were subject to oxidation and formed double-layer oxide films that can be roughly described as a porous Fe3O4 outer layer over a chrome-rich spinel inner layer. Neglecting the mass transfer corrosion effects by the flowing LBE, calculations based on Wagner's theory reproduce the experimental results on the oxide thickness, indicating that the oxide growth mechanism of steels in LBE is similar to that of steels in air/steam, with slight modification by dissolution and oxide dissociation at the liquid metal interface

191

Crevice corrosion properties of stainless steels in diluted sea water  

International Nuclear Information System (INIS)

Experiments of crevice corrosion occurrence condition, initiation rate and propagation rate were conducted for several kind of stainless steels used for feedwater-condenser system of boiling water reactor. The occurrence condition was obtained from comparison of crevice corrosion potential and corrosion potential as a function of kind of steel and chloride ion concentration is parameters. Threshold chloride concentration of crevice corrosion for SUS304L, SUS316L and SCS19A was 500ppm. The value for SUS403 was 15ppm. Constant potential test was conducted in order to obtain corrosion initiation time from current-time profile, corrosion depth from observation of the test specimen. Dependency of crevice corrosion initiation time on temperature was obtained in 6000ppm chloride diluted sea water. Maximum corrosion depth was obtained from inspection of each specimen then compared with corrosion propagation time. (author)

192

Materials corrosion and protection at high temperatures  

International Nuclear Information System (INIS)

This book was made from the lectures given in 2010 at the thematic school on 'materials corrosion and protection at high temperatures'. It gathers the contributions from scientists and engineers coming from various communities and presents a state-of-the-art of the scientific and technological developments concerning the behaviour of materials at high temperature, in aggressive environments and in various domains (aerospace, nuclear, energy valorization, and chemical industries). It supplies pedagogical tools to grasp high temperature corrosion thanks to the understanding of oxidation mechanisms. It proposes some protection solutions for materials and structures. Content: 1 - corrosion costs; macro-economical and metallurgical approach; 2 - basic concepts of thermo-chemistry; 3 - introduction to the Calphad (calculation of phase diagrams) method; 4 - use of the thermodynamic tool: application to pack-cementation; 5 - elements of crystallography and of real solids description; 6 - diffusion in solids; 7 - notions of mechanics inside crystals; 8 - high temperature corrosion: phenomena, models, simulations; 9 - pseudo-stationary regime in heterogeneous kinetics; 10 - nucleation, growth and kinetic models; 11 - test experiments in heterogeneous kinetics; 12 - mechanical aspects of metal/oxide systems; 13 - coupling phenomena in high temperature oxidation; 14 - other corrosion types; 15 - methods of oxidized surfaces analysis at micro- and nano-scales; 16 - use of SIMS in cro- and nano-scales; 16 - use of SIMS in the study of high temperature corrosion of metals and alloys; 17 - oxidation of ceramics and of ceramic matrix composite materials; 18 - protective coatings against corrosion and oxidation; 19 - high temperature corrosion in the 4. generation of nuclear reactor systems; 20 - heat exchangers corrosion in municipal waste energy valorization facilities; 21 - high temperature corrosion in oil refining and petrochemistry; 22 - high temperature corrosion in new energies industry. (J.S.)

193

Steel corrosion in ammonia solutions studied by Moessbauer spectrometry  

International Nuclear Information System (INIS)

The corrosive action of diluted ammonia solutions has been thoroughly studied until 90s. A particular interest towards studying it after this time arisen from problems relating to environment protection. We have initiated a programme which involves the study of steel samples in ammoniac solutions. The steel samples were obtained from industrial Fe-C steel with C of low concentration. The surface of the samples was diamond polished, subsequently degreased and desiccated. The corrosion process of the samples was performed in an electrolytic cell with diluted ammonia solutions of concentration ranging within 10-1 - 10-4 N. Moessbauer measurements were performed at room temperature in the transmission (TMS) and conversion electron spectroscopy (CEMS) using a conventional constant-acceleration spectrometer with a 57 Co-Rh source. The TMS spectrum shows the presence of a single sextet: ?-iron. The best fit of the CEMS spectra uses an addition wide line to the sextet. The parameters of the wide line correspond to a non-stoichiometric oxide with (probably) small particles. Also the line parameters prove that we have studied the early stage of the corrosion process. All CEMS spectra show that on the surface the directions of the ?-ray and the magnetic moments are nearly perpendicular. There is a magnetic anisotropy on the surface of the samples, which remains even in the corroded samples. In contrast TMS spectrum shows that in the interior ofS spectrum shows that in the interior of the sample the magnetic moments are in a random arrangement. The result of the corrosion is the layer appearance (non-stoichiometric iron oxide) on the sample surface. The layer thickness increases with the change of the NH3 concentration from 10-1 to 10-4 N. (authors)

194

Atmospheric Corrosion on Steel Studied by Conversion Electron Moessbauer Spectroscopy  

International Nuclear Information System (INIS)

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.

195

Corrosion of Steel in Concrete – Potential Monitoring and Electrochemical Impedance Spectroscopy during Corrosion Initiation and Propagation  

DEFF Research Database (Denmark)

A reinforced mortar specimen that allows potential measurements and electrochemical impedance spectroscopy (EIS) immediately after preparation was designed and tested. The specimen consists of a mortar cylinder with a central rebar and a concentric arrangement of embedded Ru/Ir activated titanium wires. The wires can act as both reference and counter electrode during EIS and, thus, no external electrode is required. The defined geometry solves reproducibility problems involved with application of an external reference electrode for EIS. Changes of the electromotive force (EMF) between rebar and titanium wires can be monitored immediately after preparation. The wire arrangement also allows investigation of local changes in the bulk mortar by EIS or by measuring the potential development of the titanium wires versus an external standard electrode. The specimen design was evaluated in an investigation on the effect of the steel quality and the steel surface properties on initiation and propagation of chloride-induced reinforcement corrosion. Besides untreated (as received) carbon rebars and stainless rebars, selected surface treatments and galvanization were investigated. The surface treatments included grit blasting, electrochemical and hydrochloric acid cleaning (HCl) as well as weathering. The results indicate that the investigated treatments of the carbon steel surface have no major effect on the initiation period, which was approximately 20 days under the actual conditions. The galvanized rebar appears to be protected throughout the experimental period to date (200 days), whereas active corrosion of the stainless steel appeared to be initiated after 100 days exposure.

Küter, Andre; Mason, Thomas O.

2005-01-01

196

Bimetallic corrosion of high-strength stainless steels  

International Nuclear Information System (INIS)

Through the studied on corrosion of VNS-2, VNS-59, EhI961, EhP517, EhP866, 20Kh13, 40Kh13, 95Kh18 and EhI474 in salt fog and 3 % NaCl solution it is established that contact with titanium alloys does not intensify the corrosion; contact with copper alloys strengthens the corrosion of steels excluding the VNS-2 and VNS-59 steels. Contacts with titanium and copper alloys do not reduce the resistance of the steels under consideration against corrosion cracking

197

Initial Atmospheric Corrosion of Carbon Steel in Industrial Environment  

Science.gov (United States)

The initial corrosion behavior of carbon steel subjected to Shenyang industrial atmosphere has been investigated by weight-loss measurement, scanning electron microscopy observation, x-ray diffraction, auger electron spectroscopy, and electron probe microanalysis. The experimental results reveal that the corrosion kinetics of the initial corrosion of carbon steel in industrial atmosphere follows empirical equation D = At n , and there is a corrosion rate transition from corrosion acceleration to deceleration; the corrosion products are composed of ?-FeOOH, ?-FeOOH, Fe3O4, as well as FeS which is related to the existence of sulfate-reducing bacteria in the rust layers. The effect of dust particles on the corrosion evolution of carbon steel has also been discussed.

Han, Wei; Pan, Chen; Wang, Zhenyao; Yu, Guocai

2015-02-01

198

Effect of chloride content of molten nitrate salt on corrosion of A516 carbon steel.  

Energy Technology Data Exchange (ETDEWEB)

The corrosion behavior of A516 carbon steel was evaluated to determine the effect of the dissolved chloride content in molten binary Solar Salt. Corrosion tests were conducted in a molten salt consisting of a 60-40 weight ratio of NaNO{sub 3} and KNO{sub 3} at 400{sup o}C and 450{sup o}C for up to 800 hours. Chloride concentrations of 0, 0.5 and 1.0 wt.% were investigated to determine the effect on corrosion of this impurity, which can be present in comparable amounts in commercial grades of the constituent salts. Corrosion rates were determined by descaled weight losses, corrosion morphology was examined by metallographic sectioning, and the types of corrosion products were determined by x-ray diffraction. Corrosion proceeded by uniform surface scaling and no pitting or intergranular corrosion was observed. Corrosion rates increased significantly as the concentration of dissolved chloride in the molten salt increased. The adherence of surface scales, and thus their protective properties, was degraded by dissolved chloride, fostering more rapid corrosion. Magnetite was the only corrosion product formed on the carbon steel specimens, regardless of chloride content or temperature.

Bradshaw, Robert W.; Clift, W. Miles

2010-11-01

199

Corrosion of steel and copper tubes for water supply in buildings  

International Nuclear Information System (INIS)

Corrosion test of steel-, galvanized steel- and copper-tube for water supply in buildings was carried out by simulation method. These samples were tested in the cold water and 80 deg C hot water with a condition of real situation. Basic data for estimating the life-time of each tubes was obtained from the test. According to the analysis of tap waters of major cities in Korea, most of tap waters have a good quality, but the values of Langelier Saturation Index (Is) were in the range of -1.0 to -3.4 and values of pH were about 6. So the formation of protective film by calcium carbonate salts may not be occurred and corrosion of these tubes can be progressed in this condition. Corrosion rates of steel-, galvanized steel- and copper-tube obtained from field test in cold water were 17.9 mdd, 1.02 mdd and 0.67 mdd, respectively, and were nearly constant with a test time. In hot water of 80 deg C, corrosion rate of steel-and galvanized steel-tube were about 5 times of that measured in cold water and increased with velocity of flowing water. But, in copper tube, corrosion rate was lower than that obtained in cold water and the value obtained at velocity of 0.65m/s was lower than that at 0.3 m/s. The results were discussed on the point of protective film formation. (Author)

200

A Study of Localized Corrosion in Supermartensitic Stainless Steel Weldments  

OpenAIRE

This doctoral thesis is concerned with pitting corrosion in super martensitic stainless steel (SMSS) weldments in slightly sour service. Thee main objective with the present thesis has been to find out why pitting corrosion occurs in the heat affected zone (HAZ) at ambient rather than at elevated temperatures and how the corrosion mechanism depends on the welding process. The thesis is divided into six parts. Part I gives a general introduction to martensitic stainless steels, focusing on the...

Enerhaug, Jakob

2002-01-01

201

Importance of Surface Preparation for Corrosion Protection of Automobiles  

Directory of Open Access Journals (Sweden)

Full Text Available An overview of science and technology of pretreatment process suitable for automotive finishing with cathodic electrodeposition primer is presented in details in this paper. Both the theoretical principles and practical aspects of tricationic phosphating process that are used in automotive industry are discussed in details. The characteristic features of phosphate coatings of both conventional high zinc phosphating formulations and modern tricationic phosphating formulations on steel surface are compared in details by SEM, EDX and XRD techniques. The corrosion protection of the phosphated and painted steel panels were evaluated by both salt spray test and electrochemical impedance spectroscopy (EIS. The analysis of impedance data in terms of pore resistance (Rpo, coating capacitance (Cc and breakpoint frequency (fb as a function of salt spray exposure time provides a clear insight into the mechanism of superior corrosion resistance provided by the modern tricationic phosphating formulations compared with conventional high zinc phosphating formulations.

Narayan Chandra Debnath

2013-02-01

202

Corrosion Behavior of High-Strength Bainitic Rail Steels  

Science.gov (United States)

The present work discusses corrosion behavior of newly developed bainitic steels made by isothermal heat treatment of a new steel composition (0.71 pct C, 1.15 pct Mn, 0.20 pct Ni, 0.59 pct Cr, 0.40 pct Cu, 0.35 pct Si, 0.026 pct S, 0.027 pct P, and rest Fe (weight percent)). Corrosion behavior of the pearlitic steel made by normalization is also studied. Electrochemical polarization and salt fog tests are carried out in 0.6 M NaCl. Steel rusts after salt fog tests are analyzed. Modified composition, finer microstructures, and compact rust morphology attribute to better corrosion resistance of the bainitic steels. Corrosion mechanisms for the pearlitic and bainitic steels are discussed.

Moon, A. P.; Sangal, S.; Layek, S.; Giribaskar, S.; Mondal, Kallol

2015-04-01

203

Corrosion Behavior of High-Strength Bainitic Rail Steels  

Science.gov (United States)

The present work discusses corrosion behavior of newly developed bainitic steels made by isothermal heat treatment of a new steel composition (0.71 pct C, 1.15 pct Mn, 0.20 pct Ni, 0.59 pct Cr, 0.40 pct Cu, 0.35 pct Si, 0.026 pct S, 0.027 pct P, and rest Fe (weight percent)). Corrosion behavior of the pearlitic steel made by normalization is also studied. Electrochemical polarization and salt fog tests are carried out in 0.6 M NaCl. Steel rusts after salt fog tests are analyzed. Modified composition, finer microstructures, and compact rust morphology attribute to better corrosion resistance of the bainitic steels. Corrosion mechanisms for the pearlitic and bainitic steels are discussed.

Moon, A. P.; Sangal, S.; Layek, S.; Giribaskar, S.; Mondal, Kallol

2015-01-01

204

Corrosion of SUS304 stainless steel in oxalic acid solution  

International Nuclear Information System (INIS)

The corrosion rate of oxidized and unoxidized SUS304 stainless steel was measured in 0.1M oxalic acid at 80degC under the potentiostatically polarized conditions. The dissolved amounts of Fe, Cr and Ni were determined by atomic absorption analysis after 166 min of polarization as a function of the potential. The corrosion potential and the sweep potentiostatic polarization curve were also measured in the same solution. The unoxidized specimen was severely attacked at the cathodic potential between -200 and -700 mV vs Ag-AgCl. Similar cathodic corrosion was also found, but with a decreased dissolution rate, for oxidized specimens. Since the corrosion potential of the alloy situated nearly at the boundary of active passive transition, both specimens frequently suffered localized attack due to insufficient passivation during spontaneous immersion. The dissolution rate of the surface oxide was slightly effected by the electrode potential within the active and the passive regions. Therefore, weakly anodic polarization is desirable for the dual purposes of the effective dissolution of surface oxide and the protection of substrate alloy surface. (author)

205

Influence of temperature on corrosion rate and porosity of corrosion products of carbon steel in anoxic bentonite environment  

Science.gov (United States)

The study focuses on the porosity of layers of corrosion products and its impact on corrosion rate of carbon steel in moist bentonite. Measurements were performed in an aggressive Czech type of bentonite - Rokle B75 at temperatures of 90 and 40 °C. Aggressiveness of B75 bentonite consists in low content of chlorides. Presence of chlorides in pore solution allows formation of more protective magnetite. The evaluation was made by electrochemical techniques (red/ox potential, open circuit potential, linear polarization resistance, impedance spectroscopy) and resistometric sensor measurements. The result imply that the higher the temperature the more compact is the layer of corrosion products that slightly decelerates corrosion rate compared to the state at 40 °C. The state of corrosion products at both temperatures is reversible.

Stoulil, J.; Ka?ok, J.; Kou?il, M.; Parschová, H.; Novák, P.

2013-11-01

206

A Novel Hydrazinecarbothioamide as a Potential Corrosion Inhibitor for Mild Steel in HCl  

Directory of Open Access Journals (Sweden)

Full Text Available 2-(1-methyl-4-((E-(2-methylbenzylideneamino-2-phenyl-1H-pyrazol-3(2H-ylidene-hydrazineecarbothioamide (HCB was synthesized as a corrosion inhibitor from the reaction of 4-aminoantipyrine, thiosemicarbazide and 2-methylbenzaldehyde. The corrosion inhibitory effects of HCB on mild steel in 1.0 M HCl were investigated using potentiodynamic polarization (PDP and electrochemical impedance spectroscopy (EIS. The results showed that HCB inhibited mild steel corrosion in acidic solution and inhibition efficiency increased with an increase in the concentration of the inhibitor. The inhibition efficiency was up to 96.5% at 5.0 mM. Changes in the impedance parameters suggested that HCB adsorbed on the surface of mild steel, leading to the formation of a protective film. The novel corrosion inhibitor synthesized in the present study was characterized using Fourier transform infrared spectroscopy (FTIR and nuclear magnetic resonance (NMR spectral data.

Abu Bakar Mohamad

2013-04-01

207

Corrosion of austenitic stainless steel weldments  

International Nuclear Information System (INIS)

The properties of weld metal in a specified environment should equal or better that of the base metal. However, in most cases that is not to be. The main cause for the degradation of an austenitic stainless steel (SS) weld joint is the formation of many regions with widely differing microstructures, which respond differently to the environment. The different microstructures encountered in an austenitic SS weldment include a duplex (?-ferrite + austenite) weld metal and a sensitised heat affected zone (HAZ). Their formation depends on the welding process and heat input, which controls the cooling rates in the various regions. These microstructural features deteriorate the general and localised corrosion properties of austenitic SS weld joint. Residual stresses add up to the service stresses and enhance the environment cracking susceptibilities of the weld joint besides increasing susceptibility to other forms of localized corrosion. The influence of microstructural variations in weld metal, sensitisation in HAZ and residual stresses on pitting, intergranular and stress corrosion cracking (SCC) behaviour of austenitic SS is reviewed in this paper. (author)

208

Corrosion behaviour of plastically deformed high-Mn austenitic steels  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The aim of the work was the comparison of corrosion resistance in an aqueous sulfuric acid solution of two high-manganese austenitic steels of the 0.05C-25Mn-Al-Si-Nb-Ti type in a plastically deformed state.Design/methodology/approach: Investigations were carried out on specimens obtained from a thermo-mechanically rolled sheet and then plastically deformed through bending and immersed in corrosive solutions (1N H2SO4 for 100 hours. The mass decrement was calculated by the gravimetric method, whereas the character of corrosion damages was observed in metallographic investigations using light and scanning electron microscopes both in the polished and etched states.Findings: It was found that after the thermo-mechanical processing one steel is characterized by an austenitic structure with numerous annealing twins, whereas in the second steel lamellar martensitic phases in an austenitic matrix occur. The investigations showed that the examined high-manganese steels have very low corrosion resistance in normal H2SO4. Higher impact on the corrosion resistance than the phase composition has the chemical composition. The mass decrement of the steel with martensite plates is a bit higher than that witha single-phase austenitic matrix. The specimens were intensively dissolved due to general corrosion accompanying by pitting and hydrogen cracking.Research limitations/implications: To investigate in more detail the corrosion behaviour of high-manganese austenitic steels, the polarization tests and the analysis of corrosion products should be carried out.Practical implications: The obtained results can be used for searching the appropriate way of improving the corrosion resistance of high-strength high-manganese austenitic steels.Originality/value: The corrosion resistance of two types of advanced high-manganese austenitic steels with different initial structures was compared. Hydrogen impact in austenitic steels was discussed.

A. Grajcar

2010-11-01

209

Status of corrosions protection primers for the automotive industry  

Energy Technology Data Exchange (ETDEWEB)

In Europe, 2.5 - 4 {mu}m Zn-pigmented corrosion protection primers (CPP) are being used by the automotive industry. A short introduction describing the development steps leading up to the state of the art will be given and also the reasons for using it in practice. For some applications it became necessary to try to achieve a significantly higher level of corrosion resistance than this ''first generation'' type coating can offer. It was also important to lower the curing temperature of the paint considerably in order to be able to supply bake-hardening grade steels. This type of corrosion protection primer is now called the ''second generation''. The Opel-production of the Astra-family started using 2{sup nd} generation CPP (4-6 {mu}m) on chromate-free pre-treatment and EG for hood and crash box in 2004. The newest developments show a high potential to lower the coating thickness even further and thus make cost savings possible. The development process is still ongoing and for effective progress, a good mutual basis for laboratory evaluation of properties is of valuable support. In a Steel Institute VDEh working group (Arcelor, Corus, Salzgitter, ThyssenKrupp, voestalpine), test procedures are being generated in order to be able to correctly assess properties such as corrosion resistance, adhesion, peeling-off behavior, etc. An overview of the procedures will be given together with correlations between laboratory results and reality. To round up the paper, corrosion protection primers have a number of potentials which can be utilized by the automotive industry to justify the additional cost. Examples highlighted with results giving evidence of these potentials will be shown. (orig.)

Hoffmann-Loeser, P. [Adam Opel AG, Ruesselsheim (Germany); Schnell, A. [DaimlerChrysler, Werk Sindelfingen (Germany); Stellnberger, K.H.; Androsch, F.M. [voestalpine Stahl, Linz (Austria); Reier, T. [SZMF, Salzgitter (Germany); Lewandowski, J. [ThyssenKrupp Stahl, Duisburg (Germany); Filthaut, C. [DOC Dortmunder OberflaechenCentrum, Dortmund (Germany); Besseyrias, A. [Arcelor / R and D LEDEPP, Florange (France); Dane, C. [Corus, Ijmuiden (Netherlands); Steinbeck, G. [Steel Institute VDEh, Duesseldorf (Germany)

2005-07-01

210

Corrosion fatigue in nitrocarburized quenched and tempered steels  

Science.gov (United States)

In order to investigate the fatigue strength and fracture mechanism of salt bath nitrocarburized steels, specimens of the steels SAE 4135 and SAE 4140, in a quenched and tempered state, and additionally in a salt bath nitrocarburized and oxidizing cooled state as well as in a polished (after the oxidizing cooling) and renewed oxidized state, were subjected to comparative rotating bending fatigue tests in inert oil and 5 pct NaCl solution. In addition, some of the quenched and tempered specimens of SAE 4135 material were provided with an approximately 50-?m-thick electroless Ni-P layer, in order to compare corrosion fatigue behavior between the Ni-P layer and the nitride layers. Long-life corrosion fatigue tests of SAE 4135 material were carried out under small stresses in the long-life range up to 108 cycles with a test frequency of 100 Hz. Fatigue tests of SAE 4140 material were carried out in the range of finite life (low-cycle range) with a test frequency of 13 Hz. The results show that the 5 pct NaCl environment drastically reduced fatigue life, but nitrocarburizing plus oxidation treatment was found to improve the corrosion fatigue life over that of untreated and Ni-P coated specimens. The beneficial effect of nitrocarburizing followed by oxidation treatment on cor-rosion fatigue life results from the protection rendered by the compound layer by means of a well-sealed oxide layer, whereby the pores present in the compound layer fill up with oxides. The role of inclusions in initiating fatigue cracks was investigated. It was found that under corrosion fatigue conditions, the fatigue cracks started at cavities along the interfaces of MnS inclusions and matrix in the case of quenched and tempered specimens. The nitrocarburized specimens, however, showed a superposition of pitting corrosion and corrosion fatigue in which pores and nonmetallic inclusions in the compound layer play a predominant role concerning the formation of pits in the substrate.

Khani, M. Karim; Dengel, D.

1996-05-01

211

Silica nanocontainers for active corrosion protection  

Science.gov (United States)

Novel self-healing protective coatings with nanocontainers of corrosion inhibitors open new opportunities for long-term anticorrosion protection of different metallic materials. In this paper a new type of functional nanoreservoir based on silica nanocapsules (SiNC) synthesized and loaded with corrosion inhibitor 2-mercaptobenzothiazole (MBT) in a one-stage process is reported for the first time. Unlike conventional mesoporous silica nanoparticles, SiNC possess an empty core and shell with gradual mesoporosity, arising from the particular conditions of the synthetic route adopted, which confers significant loading capacity and allows prolonged and stimuli-triggered release of the inhibiting species. The kinetics of inhibitor release was studied at different pH values and concentrations of NaCl. The results show a clear dependence of the release profiles on corrosion relevant triggers such as pH and Cl- concentration. When SiNC loaded with MBT are dispersed in NaCl solution, there is a significant decrease of the corrosion activity on aluminium alloy 2024. More importantly, when SiNC-MBT is added to a conventional water-based coating formulation, the modified coating hampers corrosion activity at the metal interface, better than in the case of direct addition of corrosion inhibitor. Furthermore, self-healing is observed before and after artificially inflicting defects in the modified coatings. As a result, the developed nanocontainers show high potential to be used in new generation of active protective coatings.

Maia, Frederico; Tedim, João; Lisenkov, Aleksey D.; Salak, Andrei N.; Zheludkevich, Mikhail L.; Ferreira, Mário G. S.

2012-02-01

212

Resistance of domestic structural steels against sulfide corrosion cracking  

International Nuclear Information System (INIS)

Paper presents the results of investigation into some tube and structural steels, as well as, into welded junctions concerning the resistance to sulfide corrosion cracking. It is shown that purification of perlite tube steels using well-known techniques may increase their resistance up to the level of the best hydrosulfide-resistant steels manufactured by foreign firms

213

Investigation of Carbon steel corrosion in water base drilling mud  

Directory of Open Access Journals (Sweden)

Full Text Available Carbon steel, the most widely used engineering material, accounts for approximately 85%, of the annual steel production worldwide. Despite its relatively limited corrosion resistance, carbon steel is used in large tonnages in marine applications, nuclear power and fossil fuel power plants, transportation, chemical processing, petroleum production and refining, pipelines, mining, construction and metal-processing equipment. This paper Investigate Carbon steel corrosion in water. The corrosion rate in production and casing pipes in water base drilling mud (packer fluid, different salt concentration (100gm/L , 150 gm/L , 200gm/L have been used and different temperature (30co , 50 co , 70 co have been investigated. Weight loss and polarization methods were applied. The results indicate that the corrosion rates decrease with the increasing of salt concentration while the corrosion rates increase with increasing of temperature

Fadhil Sarhan Kadhim

2011-01-01

214

Hot Corrosion Behavior of HVOF Sprayed Coatings on ASTM SA213-T11 Steel  

Science.gov (United States)

Cr3C2-NiCr, NiCr, WC-Co and Stellite-6 alloy coatings were sprayed on ASTM SA213-T11 steel using the HVOF process. Liquid petroleum gas was used as the fuel gas. Hot corrosion studies were conducted on the uncoated as well as HVOF sprayed specimens after exposure to molten salt at 900 °C under cyclic conditions. The thermo-gravimetric technique was used to establish the kinetics of corrosion. XRD, SEM/EDAX and EPMA techniques were used to analyze the corrosion products. All these overlay coatings showed a better resistance to hot corrosion as compared to that of uncoated steel. NiCr Coating was found to be most protective followed by the Cr3C2-NiCr coating. WC-Co coating was least effective to protect the substrate steel. It is concluded that the formation of Cr2O3, NiO, NiCr2O4, and CoO in the coatings may contribute to the development of a better hot-corrosion resistance. The uncoated steel suffered corrosion in the form of intense spalling and peeling of the scale, which may be due to the formation of unprotective Fe2O3 oxide scale.

Sidhu, H. S.; Sidhu, B. S.; Prakash, S.

2007-09-01

215

Corrosion Behavior of Copper-Steel Particulate Composite  

Directory of Open Access Journals (Sweden)

Full Text Available This work was conducted to study the corrosion behavior of the steel particle reinforced copper matrix composites, under different conditions; namely heat treatment, concentration of corrosion media, and different weight percent of steel particles.The density, corrosion rate, micro-structure, and Vickers micro-hardness, were investigated. The results showed that composites with limited steel particle contents can be used. The microstructure of the composites showed severe corrosion of the steel particles especially in the low steel particle content ones, which gave an effect more or less similar to the pitting corrosion. The Vickers micro-hardness showed a development in the hardness of the different zones of the composite due to the effect of the cold working and subsequent annealing, but yet with the same marked increment in micro-hardness at the particle-matrix interface. The later gave a strong indication that diffusion was taken place. Corrosion rate increased with increasing steel particle contents, because of severity corrosion in steel particles.

J. T. AL-Haidary

2011-06-01

216

78 FR 19210 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Final Results of...  

Science.gov (United States)

...Administration [C-580-818] Corrosion-Resistant Carbon Steel Flat...countervailing duty (CVD) order on corrosion-resistant carbon steel flat...Ltd. (HYSCO), and Pohang Iron & Steel Co. Ltd. (POSCO...1\\ See Corrosion-Resistant Carbon Steel...

2013-03-29

217

Corrosion of ODS steels in lead-bismuth eutectic  

Energy Technology Data Exchange (ETDEWEB)

Oxide dispersion strengthened (ODS) ferritic steels are advanced materials being developed for high temperature applications. Their properties (high temperature strength, creep resistance, corrosion/oxidation resistance) make them potentially usable for high temperature applications in liquid metal cooled systems like liquid lead-bismuth eutectic cooled reactors and spallation sources. Corrosion tests on five different ODS alloys were performed in flowing liquid lead-bismuth eutectic in the DELTA Loop at the Los Alamos National Laboratory at 535 deg. C for 200 h and 600 h. The tested materials were chromium alloyed ferritic/martensitic steels (12YWT, 14YWT, MA957) and Cr-Al alloyed steels (PM2000, MA956). It was shown that the Al alloyed ODS steel above 5.5 wt% Al (PM2000) is highly resistant to corrosion and oxidation in the conditions examined, and that the corrosion properties of the ODS steels depend strongly on their grain size.

Hosemann, P. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Montanuniversitaet Leoben (Austria)], E-mail: peterh@lanl.gov; Thau, H.T.; Johnson, A.L. [University of Nevada Las Vegas (United States); Maloy, S.A.; Li, N. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States)

2008-02-15

218

In situ 3D monitoring of corrosion on carbon steel and ferritic stainless steel embedded in cement paste  

International Nuclear Information System (INIS)

Highlights: • The morphology of the corrosion of steel in cement paste was studied in situ. • During galvanostatic corrosion, carbon steel reinforcement corroded homogeneously. • On ferritic stainless steel, deep corrosion pits formed and caused wider cracks. • The measured rate of steel loss correlated well with Faraday’s law of electrolysis. - Abstract: In a X-ray microcomputed tomography study, active corrosion was induced by galvanostatically corroding steel embedded in cement paste. The results give insight into corrosion product build up, crack formation, leaching of products into the cracks and voids, and differences in morphology of corrosion attack in the case of carbon steel or stainless steel reinforcement. Carbon steel was homogeneously etched away with a homogeneous layer of corrosion products forming at the steel/cement paste interface. For ferritic stainless steel, pits were forming, concentrating the corrosion products locally, which led to more extensive damage on the cement paste cover

219

Atmospheric corrosion of mild steel. Pt. II. Marine atmospheres  

International Nuclear Information System (INIS)

This paper summarizes the results obtained in the MICAT project for mild steel specimens exposed for 1 to 4 years in 47 marine atmospheres in the Ibero-American region. All these atmospheres were characterized for climatology, pollution and corrosion rates according to ISO standards. Complementary morphological and chemical characterization of the steel corrosion product layers (SCPLs) formed in these atmospheres was carried out. The overall analysis of results contributes to understanding, in a systematic way, how atmospheric corrosivity categories can be correlated with corrosion mechanisms. Special aspects of the atmospheres, from pure to mixed marine, were considered. (orig.)

220

Corrosion induced by cathodic hydrogen in 2205 duplex stainless steel  

Energy Technology Data Exchange (ETDEWEB)

In this work new results about the influence of cathodic hydrogen on passivity and corrosion resistance of 2205 duplex stainless steel are described. The results were discussed by taking into account hydrogen charged samples and without hydrogen. The corrosion resistance to pitting was qualified with the polarization curves. The conclusion is that, hydrogen deteriorated the passive film stability and corrosion resistance to pitting of 2205 duplex stainless steel. The presence of hydrogen in passive films increases corrosion current density and decreases the potential of the film breakdown. It was also found that degree of susceptibility to hydrogen action was dependent on the hydrogen charging conditions.

Michalska, J, E-mail: joanna.k.michalska@polsl.pl [Department of Materials Science, Silesian University of Technology, Krasinskiego 8, 40-019 Katowice (Poland)

2011-05-15

221

Electrochemical study of the crevice corrosion resistance of stainless steels: example of Cr-Mo ferritic steels  

International Nuclear Information System (INIS)

The measurement of stainless steel depassivating pH enables the crevice corrosion resistance to be evaluated. It is concluded that: Mo is more efficient than Cr; the classification of the stainless steel types is not the same for pitting and crevice corrosion resistance; crevice corrosion resistance of Cr-Mo ferritic steels is similar to that of Cr-Ni-Mo austenitic steels

222

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

International Nuclear Information System (INIS)

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

223

Corrosion behaviour and galvanic coupling with steel of Al-based coating alternatives to electroplated cadmium  

International Nuclear Information System (INIS)

The galvanic corrosion behaviour of bare steel coupled to steel with an Al–Zn flake inorganic spin coating, an Al-based slurry sprayed coating, an arc sprayed Al coating and electroplated cadmium has been investigated. The sacrificial and galvanic behaviour of the coatings was studied in 3.5 wt. % NaCl solution using open-circuit potential, potentiodynamic polarisation and electrochemical noise measurements. The coatings were characterised by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Experimental results showed that the Al-based slurry sprayed coating exhibited an open-circuit potential closer to the steel substrate than other coatings, as well as a low corrosion current density and a more positive corrosion potential. In terms of the galvanic suitability of the investigated coatings for the steel substrate, both the Al–Zn flake inorganic spin coating and the Al-based slurry sprayed coating show low galvanic current, in comparison with the arc sprayed Al coating and electroplated cadmium. This behaviour confirms their superior cathodic protection capability and galvanic compatibility over other coatings tested. Electrochemical noise measurements provide accurate information on the coatings' galvanic behaviour, which can be complimented by the data obtained from superposition of potentiodynamic corrosion scans of the coating and bare steel, provided that the corrosion potential difference between the two materials does not exceed 300 mV. - Highlights: • Al-based slurry coating has best galvanic compatibility with steel. • Mg, Cr, P in Al-based slurry coating reinforce its corrosion resistance. • Ennoblement of Al–Zn flake coating compromises its cathodic protection. • Poor corrosion behaviour of arc sprayed Al coating caused by rough morphology. • Electrochemical noise provides adequate estimates of galvanic behaviour

224

Corrosion study of two ferritic steels by liquid lead circulating in a thermoshyphon: Model research  

International Nuclear Information System (INIS)

In the field of the investigations concerning direct contact for Molten Salts Reactors, a study of the behaviour of ferritic steels in flowing liquid lead has been untertaken. For this purpose, two thermal convection loops were constructed, respectively of Chromesco 3 and EM 12 steels. They operated during 3000 h, without plugging, with a hot leg temperature of 5500C, a ?T of 800C and a lead flow velocity of 0.1 m/s. It appears that the hot leg corrosion and the associated deposition in the cold leg are significantly more pronounced for Chromesco 3 compared to EM 12 steel. A unsophisticated model, only taking into account the phenomena of dissolution-deposition, liquid state diffusion and transport of the dissolved metal in liquid lead allows to explain qualitatively the results obtained with Chromesco 3 steel. Concerning EM 12 steel, the formation of a protective chromium rich oxide layer is probably involved in the corrosion mechanism. (orig.)

225

Corrosion of reinforcement bars in steel ibre reinforced concrete structures  

DEFF Research Database (Denmark)

Steel fibres have been known as an alternative to traditional reinforcement bars for special applications of structural concrete for decades and the use of steel fibre reinforced concrete (SFRC) has gradually increased in recent years. Steel fibres lead to reduced crack widths in concrete formed, among other reasons, due to shrinkage and/or mechanical loading. Steel fibres are nowadays also used in combination with traditional reinforcement for structural concrete, where the role of the fibres is to minimize the crack widths whereas the traditional reinforcement bars are used for structural purpose. Although such, so-called, combined reinforcement systems, are gaining impact within the construction industry, they are only marginally covered by existing guidelines for structural design and the literature concerning their mechanical and, in particular their durability aspects, is sparse. The aim of the work presented in this Ph.D. thesis was to quantify the influence of steel fibres on corrosion of traditionalreinforcement bars embedded in uncracked concrete as well as cracked concrete. Focus of the work was set on the impact of steel fibres on corrosion propagation in uncracked concrete and the influence of steel fibres on initiation and propagation of cracks in concrete. Moreover, the impact of fibres on corrosion-induced cover cracking was covered. The impact of steel fibres on propagation of reinforcement corrosion was investigated through studies of their impact on the electrical resistivity of concrete, which is known to affect the corrosion process of embedded reinforcement. The work concerning the impact of steel fibres on initiation and propagation of cracks was linked to corrosion initiation and propagation of embedded reinforcement bars via additional studies. Cracks in the concrete cover are known to alter the ingress rate of depassivating substances and thereby influence the corrosion process. The Ph.D. study covered numerical as well as experimental studies. Electrochemically passive steel fibres are electrically isolating thus not changing the electrical resistivity of concrete, whereas electrochemically active (depassivated/corroding) steel fibres are conducting. The impact of electrochemically active (depassivated/corroding) steel fibres on the electrical resistivity of SFRC was studied experimentally and analytically herein. Those studies showed that the addition of electrically conductive steel fibres may potentially reduce the electrical resistivity of concrete. Numerical studies of the correlation between the corrosion rate and the electrical resistivity of concrete were presented to study the impact of conductive steel fibres on the corrosion propagation phase of reinforcement bars. It was observed that under extreme conditions, viz. conductive (depassivated/corroding) steel fibres throughout the concrete volume, the reduction of the electrical resistivity caused by conductive fibres lead to a remarkable increase in the corrosion rate. However it is stressed that the case of corroding steel fibres throughout the concrete volume is somewhat hypothetical due to the very high corrosion-resistance of embedded steel fibres. Thus the investigated case refers to a worst-case scenario. Numerical and experimental studies on the impact of steel fibres on initiation and propagation of load-induced cracks in concrete showed that the steel fibres restrained the crack width of a bending crack through the concrete cover, once the crack was formed. Moreover the numerical studies showed that the length of separation at the concrete/steel-bar interface (displacement discontinuity perpendicular to the reinforcement bar) was reduced for SFRC compared to plain concrete, whereas there was no clear impact on the slip at the concrete/steel-bar (displacement discontinuity parallel to the reinforcement bar) caused by the steel fibres. Additional experimental and numerical studies concerning corrosion of reinforcement embedded in cracked concrete (plain concrete and SFRC) showed that the time-to-corrosion-intiation was similar

Solgaard, Anders Ole Stubbe

2014-01-01

226

Prediction of external corrosion for steel cylinders  

International Nuclear Information System (INIS)

The US Department of Energy (DOE) currently manages the UF6 Cylinder Program (the program). The program was formed to address the depleted-uranium hexafluoride (UF6) stored in approximately 50,000 carbon steel cylinders. The cylinders are located at three DOE sites: the K-25 site (K-25) at Oak Ridge, Tennessee; the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The System Requirements Document (SRD) (LMES 1996a) delineates the requirements of the program. The appropriate actions needed to fulfill these requirements are then specified within the System Engineering Management Plan (SEMP) (LMES 1996b). The report presented herein documents activities that in whole or in part satisfy specific requirements and actions stated in the UF6 Cylinder Program SRD and SEMP with respect to forecasting cylinder conditions. The wall thickness projections made in this report are based on the assumption that the corrosion trends noted will continue. Some activities planned may substantially reduce the rate of corrosion, in which case the results presented here are conservative. The results presented here are intended to supersede those presented previously, as the quality of several of the datasets has improved

227

AFM study of steel corrosion in aqueous solutions in concrete  

Directory of Open Access Journals (Sweden)

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

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

Díaz-Benito, B.

2011-03-01

228

Corrosion Protection under Thermal Insulation  

OpenAIRE

Corrosion under insulation (CUI) is an extensive and costly problem for the petrochemical and chemical industry. Both good coatings to mitigate the problem and test methods to ensure the quality of these coatings are needed. In this thesis, four coatings; standard epoxy coating, epoxy phenolic coating, titanium modified inorganic copolymer (TMIC) and thermally sprayed aluminium (TSA), were tested for their ability to mitigate the problem. To simulate the CUI conditions, several test methods m...

Sigbjørnsen, Karen

2013-01-01

229

Investigation of Fecraly Coating on Corrosion Behaviour of Mild Steel  

OpenAIRE

Steel has found wide application in hot rolling equipments in the steel industry and the oil rig structures in sea water. These equipments are frequently subjected to corrosive and temperature condition which causes severe damage to them, hence the need to develop steel suitable to withstand these conditions in terms of surface treatment. This research work investigates the effect of FeCrAlY coating on mild steel under high temperature and aggressive environment. Iron based coatings are used ...

Agboola, Joseph B.

2009-01-01

230

Evaluation of corrosion protection of carbon black filled fusion-bonded epoxy coatings on mild steel during exposure to a quiescent 3% NaCl solution  

International Nuclear Information System (INIS)

Carbon black (CB) was mixed with fusion-bonded epoxy (FBE) coatings to generate a series of formulations with 0.5-4% by weight of carbon black. The degradation of these FBE coatings on mild steel exposed to a quiescent 3% NaCl solution was monitored using electrochemical impedance spectroscopy (EIS). The experimental results showed that the electrochemical behaviour of coated systems changed dramatically when the CB concentration reached 3% by weight. This phenomenon was relevant to the formation of the percolation regime in the coating, at which a sharp drop in the electrical resistance of the coating was achieved by the generation of a continuous conducting network. A comparison of the protective properties of the FBE coatings filled with various CB loadings, along with the inspection of view underneath the coatings, indicated that the protective performance of the FBE coating was significantly improved when the CB loading exceeded the threshold concentration. This conclusion was confirmed by the results obtained from Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) measurements

231

Lifetime prognosis for corrosion-resistant coatings on St3 steel  

Energy Technology Data Exchange (ETDEWEB)

The goal of this work was to describe the function of the generalized parameter of protection-coating quality A{sub p} as a function of time t, and to estimate the lifetime of the coatings studied. The corrosion resistance of the coatings were studied on St3 steel.

Gorokhov, E.V.; Vysotskii, Yu.B.; Donya, A.P. [Makeev Inst. of Building Engineers (Russian Federation)] [and others

1994-03-01

232

Corrosion protection of metals by silane surface treatment  

Science.gov (United States)

The need for toxic chromate replacements in metal-finishing industries has prompted an intensive search for replacement technologies in recent years. Among the replacements that have been proposed, those that are based upon the use of organofunctional silanes rank very high in terms of performance, broad applicability as well as ease of application. This dissertation presents a four-part work: (1) structural characterization of silane films on metals, (2) mechanism studies of silane-treated metal systems, (3) development of water-based silane systems, and (4) measurements of other properties of silane films. In part 1, silane films, i.e., bis-[triethoxysilylpropyl]tetrasulfide (bis-sulfur silane) and bis-[trimethoxysilylpropyl]amine (bis-amino silane) were deposited on AA 2024-T3 and were characterized mainly using reflection-absorption Fourier-transform infrared spectroscopy (FTIR-RA) and electrochemical impedance spectroscopy (EIS) techniques. In part 2, the mechanistic study of corrosion protection of AA 2024-T3 by bis-sulfur silane film was carried out. In summation, the following two factors play critical roles in the corrosion protection of AA 2024-T3: (1) the formation of a highly crosslinked interfacial layer, and (2) high water resistance of silane films. The former inhibits corrosion in the following two ways: (1) blocking favorable sites for water adsorption by the formation of AlOSi bonds at the interface which effectively reduces the tendency of aqueous corrosion; and (2) bonding tightly to the metal and thus restricting transportation of the existing corrosion products away from their original sites which hinders pit growth. It should be noted that a high density of AlOSi bonds can be obtained employing bis-silanes rather than mono-silanes. A high water resistance makes water penetration difficult in silane films. This is essential for preventing AlOSi bonds from hydrolysis. In part 3, test results for newly-developed water-based silane systems were reported. The major advantage of these silane systems is that they are highly miscible with water, which makes them more industrially acceptable than alcohol-based silanes. Test results demonstrated that these silanes provide excellent corrosion protection as well as paint adhesion on a variety metals including, Al alloys, Zn-coated steels, carbon steels, and stainless steels. Part 4 reported several other properties of silane films, such as resistivity/conductivity, mechanical properties, and thermal stabilities of silane films. (Abstract shortened by UMI.)

Zhu, Danqing

2005-07-01

233

Corrosion and corrosion fatigue resistance of steel in sea water and laboratory conditions  

International Nuclear Information System (INIS)

The effect of sea water under natural and laboratory conditions on corrosion of the structural steel and its durability during low-cycle fatigue is comparatively estimated. Corrosion and corrosion-mechanical failure of the steel during repeated-static is investigated for the first time directly in the open sea taking into account the biological factor. It is established that the nature of steel corrosion damage in sea water and in its model largely depends on conditions of the experiment. When the aggressive medium is stagnant, pitting corrosion is primary; under conditions contributing to oxygen depolarization, spots and honeycomb corrosion takes place, which are more pronounced under nature sea conditions than in laboratory

234

Passivation and Corrosion Behavior of Modified Ferritic-Pearlitic Railway Axle Steels  

Science.gov (United States)

Electrochemical polarization behavior of two newly developed ferritic-pearlitic railway axle steels (MS3 and MS6) and the standard Indian conventional axle steel has been studied in sodium borate buffer solution of pH 8.4 with and without the presence of NaCl. The polarization behavior of both the new axle steels shows close resemblance, whereas, different polarization behavior has been observed for the conventional axle steel. Electrochemical impedance spectroscopy measurements have clearly reflected significantly improved passivation behavior for the newly developed steels compared to that of the conventional axle steel. NaCl salt fog exposure tests have also shown superior corrosion resistance of the newly developed axle steels as compared to the conventional axle steel. Higher surface roughness on the corroded conventional axle steel has also been observed compared to the smoother surface in case of the new axle steels. Higher corrosion resistance of the new axle steels has been attributed to their finer microstructure and strongly adherent protective rusts.

Moon, A. P.; Sangal, S.; Srivastav, Simant; Gajbhiye, N. S.; Mondal, K.

2015-01-01

235

Synthesis of the functional derivatives of thioglycolic acid and research of influence of structural factors on their protective properties at corrosion of steel  

International Nuclear Information System (INIS)

Full text: Results of influence of structural factors investigation on protective properties of some mono-and di-replaced functional derivatives with general formulas HS-CH2COOH and R'-S-CH2-COOR, synthesized on the basis of thioglycolic acids (TGA) have been considered. It is established, that in biphasic sour system 0.04% water solution CH3COOH-kerosene, all the investigated compounds-both mono and di-replaced, process inhibitor properties. Influence of the nature, structure and lengths of radicals on efficiency of obtained compounds is also established. It is revealed, that among the investigated connections, bi-replaced derivatives of TGA: cyclohexyl propoxycarbonylmethyl sulphide and deputy ether butoxycarbonyymethyl this iconic acids are the most effective inhibitors. As well it is revealed, that all the mono-replaced derivatives of TGA, expect the compound with formula HS-CH2-COOCH2-OH, in biphasic neutral system 3% water solution NaCI- kerosene stimulate corrosion process St-3.It is established, that above-stated di-replaced derivatives TGA also process inhibitor properties in neutral system, however efficiency of these compounds turned to be much less, than in sour system

236

Contact corrosion measurements on the pair UO2+x and carbon steel 1.0330 in brines and bentonite porewater with respect to direct waste disposal  

International Nuclear Information System (INIS)

Contact corrosion between carbon steel and UO2 was studied in the MgCl2 rich Q-brine, in bentonite porewater and in saturated NaCl solution by use of contact potential and contact current measurements. In all solutions the carbon steel dominates the contact potential, so that this potential is near to the rest potential of the carbon steel. Only in solutions without precipitation of iron corrosion products, the presence of metallic iron slightly reduces the UO2 corrosion rate. If iron corrosion products precipitate, the relevant adsorption of the uranium species will be more effective than any direct cathodic corrosion protection. (orig.)

237

Corrosion behavior of carbon steels under tuff repository environmental conditions  

International Nuclear Information System (INIS)

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

238

Bacterial corrosion in marine sediments: influence of cathodic protection  

International Nuclear Information System (INIS)

In order to protect offshore structures from marine corrosion, cathodic protection is widely applied via sacrificial anodes (for example zinc or aluminium) or impressed current. In aerated seawater, steel is considered to be protected when a potential of -8050 mV/Cu.CuSO4 is achieved. In many cases, however this potential must be lowered, due to the activity of microorganisms and more specially sulfate-reducing bacteria (SRB). SRB are obligate anaerobes using sulphate as electron acceptor with resultant production of sulphide. Some of them are also able to use hydrogen as energy source, causing cathodic depolarization of steel surfaces. An experiment was performed to analyze the relation between SRB activity and use of different cathodic potentials applied to mild steel samples in marine sediments. Analytical techniques employed included lipid bio-markers and electrochemical methods. Results indicated an evolution of the bacterial community structure both on the steel and in the sediment, as a function of time and potential. The results also show that cathodically produced hydrogen promotes the growth of SRB (author)

239

Effect of segregation bands on corrosion of steel plate for ship hull  

Directory of Open Access Journals (Sweden)

Full Text Available Despite significant progress in the manufacturing of sheet metal ships carried both by optimizing the chemical compositions of steel mills as well as rolling and heat treatment, it still fails to remove the effects of persistent segregation. As a result we observed anisotropy of mechanical properties of the material which essentially complicates the process of construction for shipbuilding industry. Anisotropy of mechanical properties occurring in sheet metal hull is even more dangerous, that during their work, they are exposed to continuous exposure variable charges arising from sea surface waves. Another factor weakening the resistance to cracking metal ship is sea-water, which in the surface layer is highly aerated and very aggressive corrosion. The purpose of this study is to clarify the role of the segregation bands in the process of corrosion of low alloy steels used for ship hull. It was estimate a rate of corrosion in aerated sea water areas of the metal with or without segregation bands. After corrosion tests were made observations of specimens surfaces. Inside the segregation bands were found phosphorus. The contents of it were exceeded the average this element content in the steel. At the same time areas of the sheet metal with segregation bands were slowly corroded than areas without bands, although the changes of corrosion rate was similar in nature.Corrosion activity of rich in phosphorus segregation band is similar to phosphate corrosion inhibitors. These are effective in the presenceof chloride in seawater to form a protective layer that protects against corrosion segregation band. Under the observation on scanningelectron microscope there was no change in the appearance of surface samples after corrosion tests. A future direction of research will be estimate the stress corrosion in the same species – with and without segregation bands.

M. Mazur

2010-07-01

240

Corrosion by concentrated sulfuric acid in carbon steel pipes and tanks: state of the art  

Energy Technology Data Exchange (ETDEWEB)

PETROBRAS, allied to the policy of reduction of emission of pollutants, has been adjusting the processes of the new refineries to obtain products with lower sulfur content. Thus, the sulfur dioxide, extracted from the process gases of a new refinery to be built in the Northeast, will be used to produce sulfuric acid with concentration between (94-96) %. This acid will be stored in carbon steel tanks and transported through a buried 8-km carbon steel pipe from the refinery to a pier, where it will be loaded onto ships and sent to the consumer markets. Therefore, the corrosion resistance of carbon steel by concentrated acid will become a great concern for the mentioned storage and transportation. When the carbon steel comes into contact with concentrated sulfuric acid, there is an immediate acid attack with the formation of hydrogen gas and ferrous ions which, in turn, forms a protective layer of FeSO{sub 4} on the metallic surface. The durability of the tanks and pipes made of carbon steel will depend on the preservation of this protective layer. This work presents a review of the carbon steel corrosion in concentrated sulfuric acid and discusses the preventive methods against this corrosion, including anodic protection. (author)

Panossian, Zehbour; Almeida, Neusvaldo Lira de; Sousa, Raquel Maria Ferreira de [Instituto de Pesquisas Tecnologicas (IPT), Sao Paulo, SP (Brazil); Pimenta, Gutemberg de Souza [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas e Desenvolvimento (CENPES); Marques, Leandro Bordalo Schmidt [PETROBRAS Engenharia, Rio de Janeiro, RJ (Brazil)

2009-07-01

241

Corrosion and potentiostatic hydrogenation of carbon steels in carbonate and sulfide solutions  

International Nuclear Information System (INIS)

Corrosion behaviour and hydrogenation of two structural carbon steel at controlled potentials in the interval of -1.4 V-+0.4 V in a carbonate-bicarbonate solution (pH 9.4) on the free oxygen access, solution deaeration with argon and saturation with hydrogen sulfide (pH 8.5) are studied. It is established that in the deaerated solution on the potential cathode shift is realized the steel cathode protection where as in carbonate-sulfide solution is found increasing the corrosion rate. 6 refs., 3 figs

242

Corrosion tests of an industrial apparatus made of boiler steel plates Type KL-2  

International Nuclear Information System (INIS)

The major structural material of multicompartment hydrostatical sterilizers used in the food-processing industries is a steel plate, Type KL-2. Its thickness varies between 4 and 12 mm. The elements of the apparatus in contact with water, steam and condensed water are subject to corrosion due to oxygen, carbon-dioxide and salts present in the system. A radiometric measurement technique has been used to determine the extend of corrosion in two such systems by measuring the wall-thickness. The protection provided by various inhibitor solutions were compared in a laboratory model experiment using activated steel plate samples. (author)

243

Stress-Corrosion Cracking in Martensitic PH Stainless Steels  

Science.gov (United States)

Precipitation-hardening alloys evaluated in marine environment tests. Report describes marine-environment stress-corrosion cracking (SCC) tests of three martensitic precipitation hardening (PH) stainless-steel alloys.

Humphries, T.; Nelson, E.

1984-01-01

244

Corrosion of alloy steels in oil field fluids  

International Nuclear Information System (INIS)

Laboratory and field tests have been conducted on two low alloy and two higher alloy steels at a range of brine salinities and sulfide contents typical of oil well production fluids. AISI types 4130 and 4340 show the same behavior in these fluids as mild steel. AISI type 410 stainless steel and 9% chromium - 1% molybdenum steel corrode at rates as great as that of mild steel at higher chloride or sulfide concentrations. Special corrosion inhibitors are required for higher alloy steels when they are exposed to these conditions

245

Effect of Geobacter sulfurreducens on the microbial corrosion of mild steel, ferritic and austenitic stainless steels  

International Nuclear Information System (INIS)

The influence of Geobacter sulfurreducens was tested on the anaerobic corrosion of four different steels: mild steel 1145, ferritic steel 403 and austenitic steels 304L and 316L. Within a few hours, the presence of cells induced a free potential (Eoc) ennoblement around +0.3 V on 1145 mild steel, 403 ferritic steel and 304L austenitic steels and slightly less on 316L. The kinetics of Eoc ennoblement depended on the amount of bacteria in the inoculum, but the final potential value depended essentially on the nature of the material. This effect was due to the capacity of G. sulfurreducens to create a direct cathodic reaction on steel surfaces, extracting the electrons directly from material. The presence of bacterial cells modified the corrosion features of mild steel and ferritic steel, so that corrosion attacks were gathered in determined zones of the surface. Local corrosion was significantly enhanced on ferritic steel. Potential ennoblement was not sufficient to induce corrosion on austenitic steels. In contrast G. sulfurreducens delayed the occurrence of pitting on 304L steel because of its capability to oxidize acetate at high potential values. The electrochemical behaviour of 304L steel was not affected by the concentration of soluble electron donor (acetate, 1-10 mM) or the amount of planktonic cells; it was directly linked to the biofilm coverage. After polarization pitting curves had been recorded, microscopic observations showed that pit, microscopic observations showed that pits propagated only in the surface zones where cell settlement was the densest. The study evidenced that Geobacter sulfurreducens can control the electrochemical behaviour of steels in complex ways that can lead to severe corrosion. As Geobacteraceae are ubiquitous species in sediments and soils they should now be considered as possible crucial actors in the microbial corrosion of buried equipment.

246

Effect of Geobacter sulfurreducens on the microbial corrosion of mild steel, ferritic and austenitic stainless steels  

Energy Technology Data Exchange (ETDEWEB)

The influence of Geobacter sulfurreducens was tested on the anaerobic corrosion of four different steels: mild steel 1145, ferritic steel 403 and austenitic steels 304L and 316L. Within a few hours, the presence of cells induced a free potential (E{sub oc}) ennoblement around +0.3 V on 1145 mild steel, 403 ferritic steel and 304L austenitic steels and slightly less on 316L. The kinetics of E{sub oc} ennoblement depended on the amount of bacteria in the inoculum, but the final potential value depended essentially on the nature of the material. This effect was due to the capacity of G. sulfurreducens to create a direct cathodic reaction on steel surfaces, extracting the electrons directly from material. The presence of bacterial cells modified the corrosion features of mild steel and ferritic steel, so that corrosion attacks were gathered in determined zones of the surface. Local corrosion was significantly enhanced on ferritic steel. Potential ennoblement was not sufficient to induce corrosion on austenitic steels. In contrast G. sulfurreducens delayed the occurrence of pitting on 304L steel because of its capability to oxidize acetate at high potential values. The electrochemical behaviour of 304L steel was not affected by the concentration of soluble electron donor (acetate, 1-10 mM) or the amount of planktonic cells; it was directly linked to the biofilm coverage. After polarization pitting curves had been recorded, microscopic observations showed that pits propagated only in the surface zones where cell settlement was the densest. The study evidenced that Geobacter sulfurreducens can control the electrochemical behaviour of steels in complex ways that can lead to severe corrosion. As Geobacteraceae are ubiquitous species in sediments and soils they should now be considered as possible crucial actors in the microbial corrosion of buried equipment.

Mehanna, Maha [Laboratoire de Genie Chimique, CNRS - Universite de Toulouse, 5 rue Paulin Talabot, BP1301, 31029 Toulouse (France)], E-mail: mum34@psu.edu; Basseguy, Regine; Delia, Marie-Line; Bergel, Alain [Laboratoire de Genie Chimique, CNRS - Universite de Toulouse, 5 rue Paulin Talabot, BP1301, 31029 Toulouse (France)

2009-11-15

247

Hydrogen-assisted stress corrosion cracking of high strength steel  

OpenAIRE

In this work, Slow Strain Rate Test (SSRT) testing, Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM) were used to study the effect of micro-structure, corrosive environments and cathodic polarisation on stress corrosion cracking (SCC) of two grades of high strength steels, Type A and Type B. Type A is manufactured by quench and tempered (Q&T) method. Type B, a normalize steel was used as reference. This study also supports electrochemical polarisation resistance metho...

Ghasemi, Rohollah

2011-01-01

248

PITTING CORROSION OF STAINLESS STEEL AT THE VARIOUS SURFACE TREATMENT  

OpenAIRE

The stainless steel surface treatment is very important with regard to its pitting corrosion susceptibility. An effect of various types surfacing on pitting corrosion resistance of AISI 304stainless steel is investigated in this work. The samples of the tested material are turned, blasted, peened, grinded and a half of them are pickled to achieve higher purity of surfaces and better quality of passive film. Eight types of different finished surfaces are tested by electrochemical and immersion...

Viera Zatkalíková; Tatiana Liptáková

2011-01-01

249

Corrosion under stress of AISI 304 steel in thiocyanate solutions  

International Nuclear Information System (INIS)

Corrosion susceptibility under stress of AISI 304 steel sensitized in a sodium thiocyanate solution has been studied and results were compared with those obtained with solutions of thiosulfate and tetrathionate. Sensitized steel type 304 is highly susceptible to corrosion when under intergranular stress (IGSCC) in thiocyanate solutions but the aggressiveness of this anion is less than that of the other sulphur anions studied (thiosulfate and tetrathionate). This work has been partly carried out in the Chemistry Department. (Author)

250

Influence on corrosion resistance of superficial strain hardening of parts made of austenitic stainless steels  

International Nuclear Information System (INIS)

Reactivity of strain hardened stainless steel 18-10 and 18-10 Mo in oxidizing media is very different at the surface and in the metal core. Surface corrosion or protection is very sensitive to superficial strain hardening resulting of mechanical treatments. Three physical phenomena are directly strain hardening dependent and have important consequences on corrosion resistance: 1) increase of diffusion rate of the different alloy elements, especially chromium; 2) residual superficial strain influence on stress corrosion and 3) structural transformation of metastable austenite

251

The Effect of Sour Gases and Some Anions on the Corrosion Behavior of Carbon Steel  

Scientific Electronic Library Online (English)

Full Text Available The effect of the presence of CO2 and H2S in the well water used in the petroleum plant on corrosion of carbon steel has been tested using impedance measurements. Carbon dioxide leads to decrease in the resistivity of the film developed on the metallic surface, while the effect of hydrogen sulfide i [...] s less pronounced. Scanning electron micrographs have shown that corrosion products cover only small part of metallic surface in water containing CO2. Studies under polarization conditions will allow concluding that the dissolved gases in the well water reduce the ability of the film to protect the metal against corrosion. The influence of the oxoanions and halide ions on the corrosion rate of steel has also been analyzed.

S.A., Salih; A.A., Mazhar; H., Mahanny.

252

The Effect of Sour Gases and Some Anions on the Corrosion Behavior of Carbon Steel  

Directory of Open Access Journals (Sweden)

Full Text Available The effect of the presence of CO2 and H2S in the well water used in the petroleum plant on corrosion of carbon steel has been tested using impedance measurements. Carbon dioxide leads to decrease in the resistivity of the film developed on the metallic surface, while the effect of hydrogen sulfide is less pronounced. Scanning electron micrographs have shown that corrosion products cover only small part of metallic surface in water containing CO2. Studies under polarization conditions will allow concluding that the dissolved gases in the well water reduce the ability of the film to protect the metal against corrosion. The influence of the oxoanions and halide ions on the corrosion rate of steel has also been analyzed.

S.A. Salih

2004-01-01

253

Inhibition of steel corrosion by electrosynthesized poly(o-anisidine)-dodecylbenzenesulfonate coatings  

International Nuclear Information System (INIS)

Poly(o-anisidine)-dodecylbenzenesulfonate (POA-DBSA) coatings were synthesized on stainless steel from aqueous solution containing o-anisidine and dodecylbenzene sulfonic acid by using cyclic voltammetry. These coatings were characterized by Fourier transform infrared spectroscopy (FTIR), UV-vis absorption spectroscopy, scanning electron microscopy (SEM) and cyclic voltammetry (CV). Corrosion tests of these coatings were carried out in aqueous 3% NaCl solution by using open circuit potential (OCP) measurements, potentiodynamic polarization technique, cyclic potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS). The results reveal that POA-DBSA acts as a corrosion protective coating on steel and reduces the corrosion rate (CR) of steel almost by a factor of 14.5.

254

On the corrosion behavior of a ferritic 18 Cr-2 Mo-steel  

International Nuclear Information System (INIS)

The investigations carried out with 18Cr-2Mo steel were aimed at its behaviour under pitting corrosion, crevice corrosion and stress corrosion cracking conditions. This was done in autoclave laboratory experiments and under experimental heat exchanger conditions in Rhine river water with a chloride content of max. 400 ppm. The test temperatures were 80, 100 and 1300C. Model heat exchangers were fabricated and operated to investigate the influence of filler materials and weld joints between the ferritic 18Cr-2Mo steel and a standard austenitic steel. The possibilities of fabricating tube sheers by applying a weld overaly and using explosive bonding were explored. 18Cr-2Mo steel has been shown to be suited for applications in cooling water which a chloride content of 400 ppm. No stress corrosion cracking occurs under such conditions. Tubes with a wall thickness up to 3 mm have sufficient toughness. Tube sheets can be made of boiler plate protected by an explosive cladding or a weld overlay of 18Cr-2Mo. A combination of Type 321 or 304 L and 18Cr-2Mo is possible. Provided 18Cr-2Mo is sufficiently resistant to the product to be cooled, it is an alternative to austenitic CrNi-(Mo) steels (e.g. AISI 304) when stress corrosion cracking is likely to occur. (orig.)

255

Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures  

OpenAIRE

Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for eva...

Sanjeev Kumar Verma; Sudhir Singh Bhadauria; Saleem Akhtar

2014-01-01

256

Steel corrosion in anoxic mediums with high chloride concentrations  

International Nuclear Information System (INIS)

Carbon steels are widely used in contact with chloride containing mediums, however most of the literature reports corrosion problems in solutions in contact with air, for example, sea water. There are other applications where the steel is in contact with freshwater in the absence of oxygen as is the case with materials for nuclear repositories or in petroleum production. These mediums can have varied composition but their corrosivity is usually related to the concentration of chlorides. There are no systematic studies in the literature about the influence of high chloride concentrations on the speed of steel corrosion for carbon steels in the absence of oxygen. Some work has been done using Raman and XPS spectroscopy, but these techniques have been carried out ex situ in samples submitted to the action of high chloride concentrations. This results in the appearance of corrosion products on the metal surface due to the oxidation of the surface from exposure to air before and during the use of these techniques, generating confusing and uncertain data. The lack of reliable data is due to the difficulty of applying these techniques in situ under very low oxygen conditions (less than 10 ppb) without allowing any air into the system. Since there are no studies in the literature about the influence of high concentrations of chloride on the corrosion speed of carbon steels in the absence of oxygen, this work aims to generate experimental data to evaluate the influence of hightal data to evaluate the influence of high concentrations of this anion on the corrosion speed of steel under anoxic conditions. The corrosivity of each solution was evaluated using electrochemical techniques such as corrosion potential, corrosion speed, anodic and cathodic polarization curves, cyclic voltammetries and electrochemical impedance spectroscopy to study the oxidation-reduction processes that occur with specific temperature, pH and chloride concentration conditions. Concentrated solutions of sodium chloride (50,000, 100,000 and 180,000 ppm of Cl-) were used in the absence of oxygen (concentration less than 10 ppb) and at 40oC0C and pH=7.5. The material chosen for this study was AISI 1018 steel. The results show that the corrosion speed of the carbon steel decreases with the increase in chloride concentrations and the increase in the steel's exposure time to the corrosive medium. This suggests that a high concentration of Cl- anions in the medium will provoke the adsorption of matter on the metal surface forming a homogeneous barrier that impedes corrosion by simply blocking the active reaction sites

257

Corrosion of Carbon Steel and Corrosion-Resistant Rebars in Concrete Structures Under Chloride Ion Attack  

Science.gov (United States)

Corrosion of reinforced concrete is the most challenging durability problem that threatens reinforced concrete structures, especially structures that are subject to severe environmental conditions (i.e., highway bridges, marine structures, etc.). Corrosion of reinforcing steel leads to cracking and spalling of the concrete cover and billions of dollars are spent every year on repairing such damaged structures. New types of reinforcements have been developed to avoid these high-cost repairs. Thus, it is important to study the corrosion behavior of these new types of reinforcements and compare them to the traditional carbon steel reinforcements. This study aimed at characterizing the corrosion behavior of three competing reinforcing steels; conventional carbon steel, micro-composite steel (MMFX-2) and 316LN stainless steel, through experiments in carbonated and non-carbonated concrete exposed to chloride-laden environments. Synthetic pore water solutions have been used to simulate both cases of sound and carbonated concrete under chloride ions attack. A three-electrode corrosion cell is used for determining the corrosion characteristics and rates. Multiple electrochemical techniques were applied using a Gamry PC4™ potentiostat manufactured by Gamry Instruments (Warminster, PA). DC corrosion measurements were applied on samples subjected to fixed chloride concentration in the solution.

Mohamed, Nedal; Boulfiza, Mohamed; Evitts, Richard

2013-03-01

258

Analysis of corrosion data for carbon steels in simulated salt repository brines and acid chloride solutions at high temperatures  

International Nuclear Information System (INIS)

Carbon steel is currently the leading candidate material for fabrication of a container for isolation of high level nuclear waste in a salt repository. Since brine entrapped in the bedded salt can migrate to the container by several transport processes, corrosion is an important consideration in the long-term performance of the waste package. A detailed literature search was performed to compile relevant corrosion data for carbon steels in anoxic acid chloride solutions, and simulated salt repository brines at temperatures between ? 20 and 4000C. The hydrolysis of Mg2+ ions in simulated repository brines containing high magnesium concentrations causes acidification at temperatures above 250C, which, in turn, influences the protective nature of the magnetite corrosion product layer on carbon steel. The corrosion data for the steels were analyzed, and an analytical model for general corrosion was developed to calculate the amount of penetration (i.e., wall thinning) as a function of time, temperature, and the pressure of corrosion product hydrogen than can build up during exposure in a closed system (e.g., a sealed capsule). Both the temperature and pressure dependence of the corrosion rate of steels in anoxic acid chloride solutions indicate that the rate-controlling partial reaction is the cathodic reduction of water to form hydrogen. Variations in the composition and microstructure of the steels or the concentration of the ionic species in the chloride solutions (provided that they do not change the pH significantly) do not appear to strongly influence the corrosion rate

259

Materials corrosion and protection at high temperatures; Corrosion et protection des materiaux a haute temperature  

Energy Technology Data Exchange (ETDEWEB)

This book was made from the lectures given in 2010 at the thematic school on 'materials corrosion and protection at high temperatures'. It gathers the contributions from scientists and engineers coming from various communities and presents a state-of-the-art of the scientific and technological developments concerning the behaviour of materials at high temperature, in aggressive environments and in various domains (aerospace, nuclear, energy valorization, and chemical industries). It supplies pedagogical tools to grasp high temperature corrosion thanks to the understanding of oxidation mechanisms. It proposes some protection solutions for materials and structures. Content: 1 - corrosion costs; macro-economical and metallurgical approach; 2 - basic concepts of thermo-chemistry; 3 - introduction to the Calphad (calculation of phase diagrams) method; 4 - use of the thermodynamic tool: application to pack-cementation; 5 - elements of crystallography and of real solids description; 6 - diffusion in solids; 7 - notions of mechanics inside crystals; 8 - high temperature corrosion: phenomena, models, simulations; 9 - pseudo-stationary regime in heterogeneous kinetics; 10 - nucleation, growth and kinetic models; 11 - test experiments in heterogeneous kinetics; 12 - mechanical aspects of metal/oxide systems; 13 - coupling phenomena in high temperature oxidation; 14 - other corrosion types; 15 - methods of oxidized surfaces analysis at micro- and nano-scales; 16 - use of SIMS in the study of high temperature corrosion of metals and alloys; 17 - oxidation of ceramics and of ceramic matrix composite materials; 18 - protective coatings against corrosion and oxidation; 19 - high temperature corrosion in the 4. generation of nuclear reactor systems; 20 - heat exchangers corrosion in municipal waste energy valorization facilities; 21 - high temperature corrosion in oil refining and petrochemistry; 22 - high temperature corrosion in new energies industry. (J.S.)

Balbaud, F.; Desgranges, Clara; Martinelli, Laure; Rouillard, Fabien [CEA-Saclay, DEN, DPC, SCCME, Laboratoire d' Etude de la Corrosion Non Aqueuse, 91191 Gif-sur-Yvette Cedex (France); Duhamel, Cecile [Mines ParisTech, Centre des materiaux UMR-CNRS 7633, BP 87, 91003 Evry Cedex (France); Marchetti, Loic; Perrin, Stephane [CEA, Laboratoire d' Etude de la Corrosion Aqueuse (France); Molins, Regine [Mines ParisTech, Direction de la Recherche, 60 Bvd Saint Michel, 75272 Paris Cedex 06 (France); Chevalier, S.; Heintz, O. [Laboratoire interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Univ. de Bourgogne, Dijon (France); David, N.; Fiorani, J.M.; Vilasi, M. [Institut Jean Lamour, UMR 7198, Univ. Henri Poincare Nancy-1 - CNRS, 54506 Vandoeuvre-les-Nancy (France); Wouters, Y.; Galerie, A. [SIMAP UMR CNRS 5266, Grenoble-INP/UJF, 1130 rue de la Piscine BP 75, 38402 Saint-Martin-d' Heres Cedex (France); Mangelinck, D. [IM2NP, UMR6242, CNRS, Univ. Paul Cezanne, Case 142, Faculte de Saint Jerome, 13397 Marseille Cedex 20 (France); Viguier, B.; Monceau, D. [Univ. de Toulouse, Institut Carnot CIRIMAT, INP-ENSIACET, 4 allee Emile Monso, BP 44362, 31030 Toulouse Cedex 4 (France); Soustelle, M. [Ecole nationale superieure des mines, Saint Etienne (France); Pijolat, M. [Centre Spin, Ecole des mines de Saint Etienne (France); Favergeon, J.; Brancherie, D.; Moulin, G.; Dawi, K. [Laboratoire Roberval, UTC (France); Wolski, K.; Barnier, V. [Centre SMS, EMSE, UMR 5146, LCG, Univ. de Lyon, 158 Cours Fauriel, 42023 Saint Etienne (France); Rebillat, F. [LCTS, Univ. de Bordeaux (France); Lavigne, O. [Onera, Dep. Materiaux et Structures Metalliques, BP 72, 29 av. de la Division Leclerc, 92322 Chatillon (France); Brossard, J.M. [Dep. energetique et procedes, Veolia Environnement Recherche et Innovation, Limay (France); Ropital, F. [IFP Energies Nouvelles, BP 3, 69360 Solaize (France); Mougin, J. [CEA-Liten, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

2011-07-01

260

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

Directory of Open Access Journals (Sweden)

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

Elkais Ali Ramadan

2011-01-01

261

Experimental and theoretical studies of thiazoles as corrosion inhibitors for mild steel in sulphuric acid solution  

International Nuclear Information System (INIS)

Graphical abstract: The inhibition effect of 2-amino-5-mercapto-1,3,4-thiadiazole and 2-mercaptothiazoline on mild steel corrosion in 1.0 M H2SO4 was studied using electrochemical techniques. The effects of the presence of extra NH2 group and N atom in 2A5MT on the ability to act as corrosion inhibitors were investigated by theoretical calculations. Highlights: ? The inhibition effects of thiazoles on mild steel corrosion in 1.0 M H2SO4 were studied. ? It was shown that both thiazole compounds act as excellent corrosion inhibitors for mild steel. ? The high inhibition efficiency was attributed to the adsorption of the inhibitor molecules on the metal surface. ? Langmuir adsorption isotherm exhibited the best fit to the experimental data. ? Quantum chemical calculations show there is a correlation between inhibitive property and molecular parameters. - Abstract: The inhibition effects of 2-amino-5-mercapto-1,3,4-thiadiazole (2A5MT) and 2-mercaptothiazoline (2MT) on mild steel corrosion in 1.0 M H2SO4 were studied with potentiodynamic polarization, linear polarization resistance and electrochemical impedance spectroscopy techniques. It was shown that both 2A5MT and 2MT act as good corrosion inhibitors for mild steel protection. The high inhibition efficiencies were attributed to the simple blocking effect by adsorption of inhibitor molecules on the steel surface. The effects of the prl surface. The effects of the presence of extra NH2 group and N atom in 2A5MT on the ability to act as corrosion inhibitors were investigated by theoretical calculations.

262

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

International Nuclear Information System (INIS)

In this work, 304L stainless steel samples were exposed at 700 °C for 10hrs in different corrosive environments; dry oxygen, molten salt, and molten salt + dry oxygen. The corrosion behavior of samples was analyzed using weight change measurement technique, optical microscope (OM) and Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray (EDX). The existence phases of corroded sample were determined using X-ray Diffraction (XRD). The lowest corrosion rate was recorded in dry oxygen while the highest was in molten salt + dry oxygen environments with the value of 0.0062 mg/cm2 and ?13.5225 mg/cm2 respectively. The surface morphology of sample in presence of salt mixture showed scale spallation. Oxide scales of Fe3O4, Fe2O3 were the main phases developed and detected by XRD technique. Cr2O3 was not developed in every sample as protective layers but chromate-rich oxide was developed. The cross-section analysis found the oxide scales were in porous, thick and non-adherent that would not an effective barrier to prevent from further degradation of alloy. EDX analysis also showed the Cr-element was low compared to Fe-element at the oxide scale region

263

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-09-03

264

Corrosion resistance and microstructure of nitrogen plasma source ion implanted bearing steel  

International Nuclear Information System (INIS)

Feasibility of plasma source ion implantation (PSII) treatments for metal corrosion protection of bearing steel in humid environments has been investigated, following successful results with aluminum alloy. The bearing steel coupons have been treated by nitrogen PSII with a statistically designed range of processing conditions, including stage bias implant voltage, and dose. Corrosion properties of the implanted samples were tested using aerated distilled water (72, 168, and 720 hours), 90 F, 90% RH air (24, 120, 816, and 1,464 hours), and a nitric acid soak. The results are compared favorably with 400 C stainless steel, and 52100 steel with nitrogen and argon recoil-implanted chromium. Evidence is seen for an optimal process contour (low voltage-high dose; high voltage-low dose). Results from microstructure analysis will also be presented

265

Corrosion inhibition of stainless steel by a sulfate-reducing bacteria biofilm in seawater  

Science.gov (United States)

Corrosion inhibition of stainless steel due to a sulfate-reducing bacteria (SRB) biofilm in seawater was studied. By atomic force microscopy, a layer of fish-scale-like biofilm was found to form as stainless steel coupons were exposed to the culture media with SRB, and this biofilm grew more and more compact. As a result, coupons' surface under the biofilm turned irregular less slowly than that exposed to the sterilized culture media. Then, physicoelectric characteristics of the electrode/biofilm/solution interface were investigated by electrochemical impedance spectroscopy (EIS), and the coverage of the biofilm as well as the relative irregularity of coupons' surface was also recorded by EIS spectra. Finally, anodic cyclic polarization results further demonstrated the protective property of the biofilm. Therefore, in estimation of SRB-implicated corrosion of stainless steel, not only the detrimental SRB metabolites but also the protective SRB biofilm as well should be taken into account.

Li, Fu-shao; An, Mao-zhong; Duan, Dong-xia

2012-08-01

266

Ranitidine Drugs as Non-Toxic Corrosion Inhibitors for Mild Steel in Hydrochloric Acid Medium  

Directory of Open Access Journals (Sweden)

Full Text Available Expired ranitidine was tested as a corrosion inhibitor for mild steel in 1 M HCl using different techniques: weight loss, potentiodynamic polarization, open circuit potential and electrochemical impedance spectroscopy. The polarization resistance (Rp value increased with increase in the concentration of the inhibitor. Results obtained revealed that ranitidine performed excellently as a corrosion inhibitor for mild steel in this medium at 303 K. The protection efficiency increased with increasing inhibitor concentration. The maximum protection efficiency of 90% has been obtained at 400 ppm. On the other hand, the efficiency decreases with increasing temperature. The adsorption of the inhibitor on the mild steel surface followed Langmuir adsorption isotherm model. The activation and thermodynamic parameters of dissolution and adsorption were calculated and discussed. The negative value of ?Gads (-40 kJ mol-1 indicates spontaneous chemical adsorption. Results obtained from polarization, EIS and weight loss measurements are in good agreement with each other.

R.S. Abdel Hameed

2011-01-01

267

Corrosion Behavior of IF Steel in Various Media and Its Comparison with Mild Steel  

Science.gov (United States)

The present work discusses corrosion behavior of an interstitial-free (IF) steel in 0.6 M NaCl, 1 M NaOH, and 1 M HCl solutions, and its comparison with mild steel (MS). Dynamics polarization and AC Impedance Spectroscopy explain different polarization behaviors of the steel samples. All the steels were exposed to open atmosphere for 100 days, and to 0.6 M NaCl salt fog for 30 days. Scanning electron microscopy, x-ray diffraction, and Raman and Fourier Transformed Infrared Spectroscopy were used to characterize microstructure of the steels, rust constituents, and morphologies. Corrosion behavior of the steels has close relation with the morphology and constituents of the rusts. It has been observed that the corrosion in the IF and MS steels is uniform in nature.

Singh, G. P.; Moon, A. P.; Sengupta, S.; Deo, G.; Sangal, S.; Mondal, K.

2015-03-01

268

Poly(o-phenylenediamine) as an inhibitor of mild steel corrosion in HCl solution  

International Nuclear Information System (INIS)

The inhibition properties of the electro-prepared P(o-phenylenediamine), P(oPD), on the corrosion rate of mild steel (MS) in HCl solutions have been investigated under different experimental conditions using weight loss and potentiodynamic polarization techniques. The data obtained from the two techniques are comparable and showed that the presence of P(oPD) in the acid solutions suppresses the corrosion rate of MS indicating that the polymer acts as corrosion inhibitor. The inhibition efficiency (IE%) of the polymer enhances with increasing its concentration and decreases with an increase in temperature. The inhibition occurs through adsorption and formation of barrier film on the metal surface which separates the metal from direct contact with the corrosive medium and hence protects the metal against the corrosion. Langmuir isotherm fits well with the experimental data. Thermodynamic parameters for both dissolution and adsorption processes were determined.

269

Poly(o-phenylenediamine) as an inhibitor of mild steel corrosion in HCl solution  

Energy Technology Data Exchange (ETDEWEB)

The inhibition properties of the electro-prepared P(o-phenylenediamine), P(oPD), on the corrosion rate of mild steel (MS) in HCl solutions have been investigated under different experimental conditions using weight loss and potentiodynamic polarization techniques. The data obtained from the two techniques are comparable and showed that the presence of P(oPD) in the acid solutions suppresses the corrosion rate of MS indicating that the polymer acts as corrosion inhibitor. The inhibition efficiency (IE%) of the polymer enhances with increasing its concentration and decreases with an increase in temperature. The inhibition occurs through adsorption and formation of barrier film on the metal surface which separates the metal from direct contact with the corrosive medium and hence protects the metal against the corrosion. Langmuir isotherm fits well with the experimental data. Thermodynamic parameters for both dissolution and adsorption processes were determined.

Abd El Rehim, S.S. [Chemistry Department, Faculty of Science, Ain Shams University, Cairo (Egypt); Sayyah, S.M., E-mail: smsayyah@hotmail.com [Polymer Research Laboratory, Chemistry Department, Faculty of Science, Beni-Suef University, 62514 Beni-Suef (Egypt); El-Deeb, M.M.; Kamal, S.M.; Azooz, R.E. [Polymer Research Laboratory, Chemistry Department, Faculty of Science, Beni-Suef University, 62514 Beni-Suef (Egypt)

2010-09-01

270

Multilayer coatings for corrosion protection of coal gasifier components  

International Nuclear Information System (INIS)

Deposition of TiAlN/Nb, TiAlN/Ta, TiAlN/W and TiAlN/Zr multilayer coatings on 409 stainless steel was studied by CVD in a fluidized bed reactor (FBR-CVD). The coatings consisted of four TiAlN layers with individual thickness of 2.5-3.5 ?m, and four metal interlayers with thicknesses in the range of 100-250 nm. The W interlayers suffered partial nitridation during the coating process and the resulting coatings had poor adhesion. Deposition of Zr through reduction of ZrI4 by H2 was found to be inefficient. Both TiAlN/Nb and TiAlN/Ta coatings showed good adhesion, but only TiAlN/Nb provided sulfidation resistance to 409 steel during exposure to simulated coal gas at 1173 K for 300 h. Though outward diffusion of Cr took place during the corrosion test, the results reported in this paper suggest that TiAlN/Nb coatings are promising candidates for corrosion protection of steels under typical coal gasifier conditions

271

Corrosion of steel 0Kh18N10T  

International Nuclear Information System (INIS)

Steel 0Kh18N10T is used for the manufacture of heat transfer tubes and collectors of steam generators for WWER nuclear power plants. The surface corrosion rate of this steel was studied in hydrochloric acid at different concentrations at a normal temperature of 20 degC. Three types of the steel heat treatment were chosen. In the case of tubes the effect of explosion and deformations on corrosion rate was also studied. A strong dependence was found on the concentration of hydrochloric acid: corrosion losses increased exponentially at concentrations higher than 10%. On the other hand, no dependence was found of the corrosion rate on the heat treatment technology or on the explosion or deformation treatment of the material. (Z.M.)

272

Research on general corrosion property of 304NG stainless steel  

International Nuclear Information System (INIS)

The circulating water corrosion test of 304NG stainless steel has been performed in the MARS loop of 1500 h. The quantitative estimation for general corrosion rate of the 304NG stainless steel is given. The test result showed that the general corrosion rate of 304NG stainless steel is 1.40 mg(dm2·30d) (for plate) and 1.91 mg/(dm2·30d) (for forging) under the simulation primary circulating water environment of nuclear reactor. For 0Cr18Ni10Ti, it is 4.44 mg/(dm2·30d) and 4.65 mg/(dm2·30d), respectively. The general corrosion rate of 304NG is lower than that of 0Cr18Ni10Ti under the simulation primary circulating water environment of nuclear reactor. (authors)

273

Polyethyleneimine as a corrosion inhibitor for ASTM 420 stainless steel in near-neutral saline media  

International Nuclear Information System (INIS)

The effect of polyethyleneimine (PEI) as a corrosion inhibitor for ASTM 420 stainless steel in 3% aqueous NaCl solution was studied. The results of linear polarization and cyclic polarization measurements indicate high inhibiting effectiveness of the selected organics. Moreover, from cyclic polarization measurements it can be deduced that PEI acts as an inhibitor against pitting corrosion. Immersion tests in the presence of PEI showed remarkable corrosion protection against uniform corrosion. Film persistency immersion testing indicated that once the protective layer is formed, it is very stable in a non-inhibited NaCl solution. X-ray photoelectron spectroscopy measurements showed that PEI binding is mediated by electrostatic interactions between PEI and the substrate. A dense layer of PEI might be effective either in preventing diffusion of ionic species from the film or in preventing attack by chlorine from the salt water

274

Polyethyleneimine as a corrosion inhibitor for ASTM 420 stainless steel in near-neutral saline media  

Energy Technology Data Exchange (ETDEWEB)

The effect of polyethyleneimine (PEI) as a corrosion inhibitor for ASTM 420 stainless steel in 3% aqueous NaCl solution was studied. The results of linear polarization and cyclic polarization measurements indicate high inhibiting effectiveness of the selected organics. Moreover, from cyclic polarization measurements it can be deduced that PEI acts as an inhibitor against pitting corrosion. Immersion tests in the presence of PEI showed remarkable corrosion protection against uniform corrosion. Film persistency immersion testing indicated that once the protective layer is formed, it is very stable in a non-inhibited NaCl solution. X-ray photoelectron spectroscopy measurements showed that PEI binding is mediated by electrostatic interactions between PEI and the substrate. A dense layer of PEI might be effective either in preventing diffusion of ionic species from the film or in preventing attack by chlorine from the salt water.

Finsgar, Matjaz [Jozef Stefan Institute, Department of Physical and Organic Chemistry, Jamova c. 39, SI-1000 Ljubljana (Slovenia); Fassbender, Stefan; Nicolini, Fabio [BASF SE, E-EMV/MM - J550, Metal Surface Treatment, Carl-Bosch Strasse 38, 67056 Ludwigshafen (Germany); Milosev, Ingrid [Jozef Stefan Institute, Department of Physical and Organic Chemistry, Jamova c. 39, SI-1000 Ljubljana (Slovenia)], E-mail: ingrid.milosev@ijs.si

2009-03-15

275

Corrosion resistance of high-manganese austenitic steels  

OpenAIRE

Purpose: The aim of the paper is to compare the corrosion resistance of two new-developed high-manganese austenitic steels in 1N H2SO4 and 3.5% NaCl solutions.Design/methodology/approach: The steels used for the investigation were thermo-mechanically rolled and then solution heat-treated from a temperature of 850°C. Corrosion resistance of investigated steels was examined using the immersion test. The specimens were weighed and dipped in the prepared solutions for 100 h. After the test, the ...

Grajcar, A.; S. Ko?odziej,; Krukiewicz, W.

2010-01-01

276

Recent Research and Development in Solving Atmospheric Corrosion Problems of Steel Industries in Japan  

International Nuclear Information System (INIS)

A rust layer, so called 'protective' rust layer, on a weathering low-alloy steel has strong protective ability for atmospheric corrosion of the steel. We have recently found through a large number of spectroscopic studies including Moessbauer spectroscopy that the protective rust layer forms after long-term phase transformation. The phase and structure of the rust definitely control the protective ability of the rust layer. From this recent knowledge, some new technologies have been developed. One is the surface-treatment technique that provides a possibility for obtaining the protective rust layer in a relatively short period even in the severe environments such as in marine and chloride (de-icing salts) containing environments. Others are based on selection of effective alloying elements for steel materials. These are particularly important for application in areas where protective rust layer formation may be hindered or prevented. In this paper, we mention recent progress in research and development on rusting protection by rust for atmospheric corrosion of steels in Japan.

277

78 FR 55241 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Preliminary Results of...  

Science.gov (United States)

...C-580-818] Corrosion-Resistant Carbon Steel Flat Products From the Republic...order on corrosion-resistant carbon steel flat products (CORE) from the...is certain corrosion- resistant carbon steel flat products from Korea....

2013-09-10

278

Corrosion fatigue of a superduplex stainless steel weldment  

OpenAIRE

Superduplex stainless steels have superior mechanical and corrosion properties compared to austenitic stainless steels such as the grade 300 series. This is a result of a microstructure consisting of roughly equal percentages of austenite (y) and ferrite (a) and negligible inclusion content. As a result, super duplex stainless steels are increasingly being used in the offshore oil and gas industries. It is also envisaged that they will find application in the emergent renewable energy sec...

Comer, Anthony John

2004-01-01

279

PITTING CORROSION OF STAINLESS STEEL AT THE VARIOUS SURFACE TREATMENT  

Directory of Open Access Journals (Sweden)

Full Text Available The stainless steel surface treatment is very important with regard to its pitting corrosion susceptibility. An effect of various types surfacing on pitting corrosion resistance of AISI 304stainless steel is investigated in this work. The samples of the tested material are turned, blasted, peened, grinded and a half of them are pickled to achieve higher purity of surfaces and better quality of passive film. Eight types of different finished surfaces are tested by electrochemical and immersion tests to determine corrosion behaviour in conditions where pitting is evoked by controlled potential and second by solution with high redox potential. By this way the effect of mechanical and chemical surface treatment on the resistance to pitting corrosion, character, size and shape of pits are compared in the conditions of different mechanisms of corrosion process.

Viera Zatkalíková

2011-09-01

280

Long-term corrosion behavior of cathodicly protected cask materials  

International Nuclear Information System (INIS)

The concept of a canister based on the principle of cathodic protection has been introduced. The main points for this concept are: nonself-shielding canisters require a radiation protection jacket during the operational stage of the repository; cost-efficient material for radiation protection is nodular cast iron; and multilayered canister consisting of materials which become successively more noble towards the inner shells has been found to be too large and too heavy for a repository. This problem has been overcome now by a new and cost-efficient production method. This is accomplished by immersing a tube made of stainless steel in molten GGG 40.3 at a defined temperature and letting them cool together. Dimensions and weight now meet the requirements of the repository. In case of an accident, that is intrusion of brine into the repository and contact with the canister, corrosion will start uniformly at the outer cast iron package. This package is sufficiently designed not to be used up in a projected term of 500 years. If, nonetheless, the cast iron jacket should rupture by means of corrosion or mechanical damage, a shortcircuit cell will form with the cast iron being the anode and the stainless steel acting as the cathode. The testing of welded large-scale integral structures, which can be regarded as mock-ups of a canister section, is in progress since March 1984 to demonstrate the feasibility of this container concept. Two such bodies are immersed in brine at 100 such bodies are immersed in brine at 100 degree C. Examinations with the very sensitive liquid penetration test fluorescent proved both bodies to be free of incipient cracks or local corrosion in the area of the weld seams

281

Excellent corrosion resistance of 18Cr-20Ni-5Si steel in liquid Pb-Bi  

International Nuclear Information System (INIS)

The corrosion properties of three austenitic steels with different Si contents were studied under oxygen-saturated liquid Pb-Bi condition for 3000 h. The three austenitic steels did not exhibit appreciable dissolution of Ni and Cr at 450 deg. C. At 550 deg. C, the thick ferrite layer produced by dissolution of Ni and Cr was found in JPCA and 316SS with low Si contents while the protective oxide film composed of Si and O was formed on 18Cr-20Ni-5Si steel and prevented dissolution of Ni and Cr

282

Investigation of Fecraly Coating on Corrosion Behaviour of Mild Steel  

Directory of Open Access Journals (Sweden)

Full Text Available Steel has found wide application in hot rolling equipments in the steel industry and the oil rig structures in sea water. These equipments are frequently subjected to corrosive and temperature condition which causes severe damage to them, hence the need to develop steel suitable to withstand these conditions in terms of surface treatment. This research work investigates the effect of FeCrAlY coating on mild steel under high temperature and aggressive environment. Iron based coatings are used due to low cost among other properties such as good corrosion resistance, ease of machining and high ductility when compared to hard metals.Thermal spraying of the specimens was carried out using high velocity oxygen fuel (HVOF. Corrosion test was carried out on both coated and uncoated samples. All samples were subjected to the same high temperature treatment for oxidation test.

Joseph B. AGBOOLA

2009-07-01

283

Development of Nb{sub 2}O{sub 5}|Cu composite as AISI 1020 steel thermal spray coating for protection against corrosion by soil in buried structures; Desenvolvimento e uso do composito de Nb{sub 2}O{sub 5}|Cu como revestimento aplicado por aspersao termica sobre o aco AISI 1020 para protecao contra a corrosao pelo solo em estruturas enterradas  

Energy Technology Data Exchange (ETDEWEB)

An Nb{sub 2}O|Cu corrosion-resistant coating was developed and applied onto AISI 1020 steel substrate by Powder Flame Spray. A galvanostatic electrochemical technique was employed, with and without ohmic drop, in four different soils (two corrosively aggressive and two less aggressive). Behavior of coatings in different soils was compared using a cathodic hydrogen reduction reaction (equilibrium potential, overvoltage and exchange current density) focusing on the effect of ohmic drop. Results allow recommendation of Nb{sub 2}O{sub 5}|Cu composite for use in buried structure protection. (author)

Regis Junior, Oscar [Universidade Tecnologica Federal do Parana, Ponta Grossa, PR (Brazil). Dept. de Mecanica; Silva, Jose Maurilio da; Portella, Kleber Franke [Instituto de Tecnologia para o Desenvolvimento, Curitiba, PR (Brazil). Dept. de Pesquisa em Engenharia Civil; Paredes, Ramon Sigifredo Cortes, E-mail: regis@utfpr.edu.br [Universidade Federal do Parana, Curitiba, PR (Brazil). Dept. de Mecanica

2012-07-01

284

Desenvolvimento e uso do compósito de Nb2O5|Cu como revestimento aplicado por aspersão térmica sobre o aço AISI 1020 para proteção contra a corrosão pelo solo em estruturas enterradas Development of Nb2O5|Cu composite as AISI 1020 steel thermal spray coating for protection against corrosion by soil in buried structures  

Directory of Open Access Journals (Sweden)

Full Text Available An Nb2O|Cu corrosion-resistant coating was developed and applied onto AISI 1020 steel substrate by Powder Flame Spray. A galvanostatic electrochemical technique was employed, with and without ohmic drop, in four different soils (two corrosively aggressive and two less aggressive. Behavior of coatings in different soils was compared using a cathodic hydrogen reduction reaction (equilibrium potential, overvoltage and exchange current density focusing on the effect of ohmic drop. Results allow recommendation of Nb2O5|Cu composite for use in buried structure protection.

Oscar Regis Junior

2012-01-01

285

Improving the corrosion resistance of cold rolled carbon steel by treatment with a hybrid organic/inorganic coating solution  

International Nuclear Information System (INIS)

In the past, a very popular way to reduce the corrosion rate of zinc was the use of chemical conversion layers based on Cr'+6'. However, the use of chromium salts is now restricted because of environmental protection legislation. Previous research investigated the optimum corrosion resistance of galvanized steel treated with an organic/inorganic solution containing Si. the result showed that the optimum corrosion resistance occurred by heat treatment of 190 .deg. C in 5min. In this study, one organic and three hybrid organic/inorganic coating solutions were applied to cold rolled (CR) carbon steel. The coatings were then evaluated for corrosion resistance under a salt spray test. The coating solutions examined in this study consisted of urethane only, urethane Si, urethane Si Ti, and urethane Si Ti epoxy. The results of the 7h salt spray test showed that the urethane Si Ti and urethane Si Ti epoxy coating solutions had superior corrosion resistance on CR steel

286

Performance evaluation of pectin as ecofriendly corrosion inhibitor for X60 pipeline steel in acid medium: Experimental and theoretical approaches.  

Science.gov (United States)

The corrosion inhibition effect of pectin (a biopolymer) for X60 pipeline steel in HCl medium was investigated using weight loss, electrochemical, water contact angle measurements, and scanning electron microscopy techniques. The results obtained show that pectin acts as a good corrosion inhibitor for X60 steel. Inhibition efficiency increased with increase in pectin concentration and temperature. Potentiodynamic polarization results reveal that pectin could be classified as a mixed-type corrosion inhibitor with predominant control of the cathodic reaction. The effective corrosion inhibition potential of pectin could be related to the adsorption of pectin molecules at the metal/solution interface which is found to accord with the Langmuir adsorption isotherm model and a protective film formation. Quantum chemical calculations provided insights into the active sites and reactivity parameters governing pectin activity as a good corrosion inhibitor for X60 steel. PMID:25839822

Umoren, Saviour A; Obot, Ime B; Madhankumar, A; Gasem, Zuhair M

2015-06-25

287

Efficiency of Corrosion Inhibitors on Cathodic Protection System  

Directory of Open Access Journals (Sweden)

Full Text Available This study is on experiment being carried out to determine the efficiency of in inhibitors on catholically protected medium carbon steel in sea water in Bonny and Ogbokoro in the Niger Delta region of Nigeria. The experiment was conducted using the total immersion technique in a non-flowing media containing sea water inhibited with potassium dichromate, sodium nitrate, ECIO21A, sarvor CK 368, and Kurizets 636. In the course of this research work, Cathodically protected and unprotected medium carbon steel were totally immersed in seawater containing the aforementioned inhibitors differently. Their weight loss, corrosion rate, pH value and corrosion potentials were determined at intervals of 72 hours, over 2016 hours the test lasted. The results obtained shows that inhibitor EC1021A has efficiency of 79.8%, other results are as follows: Kurizet S.636, 77%, savor CK368, 43%, potassium dichromate, 35% and sodium nitrate, 1.88%. It was concluded that EC1021A is the most efficient inhibitor, under a non-flow system.

Tobinson Briggs

2014-02-01

288

Corrosion resistance of high strength modified 13Cr steel  

Energy Technology Data Exchange (ETDEWEB)

A new 13Cr martensitic stainless steel (0.025C-13Cr-Ni-Mo) with excellent resistance to CO{sub 2} corrosion and good resistance to SSC is developed and its application limit in oil and gas environments is clarified. The CO{sub 2} corrosion rate of the 13Cr steels with Ni and Mo is less than 0.3 mm/yr at 180 C (356 F) in 20% NaCl. It is less than that of the conventional 13Cr steel (0.2C-13Cr). The corrosion rate of the steel slightly decreases with the increase in Mo and Ni content. The SSC resistance improves with the increase in Mo content. The critical partial pressure of H{sub 2}S for the 2% Mo steel is greater than 0.005 MPa at the pH value of 3.5. The effects of Ni and Cu on SSC are not distinctive for this kind of steel. These results depends on the hydrogen permeability. The critical H{sub 2}S partial pressure for the 110 grade steel is the same as that of the 95 grade steel at the pH values of 4.5 and 3.0, and is slightly lower at the pH values between 3.0 and 4.5. The new 13Cr steel proves to have excellent properties in the sweet and slightly sour environment.

Kimura, Mitsuo; Miyata, Yukio; Yamane, Yasuyoshi; Toyooka, Takaaki; Nakano, Yoshifumi [Kawasaki Steel Corp., Handa, Aichi (Japan). Technical Research Labs.; Murase, Fumio [Kawasaki Steel Corp., Handa, Aichi (Japan). Chita Works

1997-08-01

289

Mechanisms of corrosion and denting of ferritic steels in aqueous chloride at 3000C  

International Nuclear Information System (INIS)

An investigation of aqueous corrosion of 0-23% Cr ferritic steels and binary alloys has been carried out in pure water, NiCl2 solutions, and mixtures of FeCl2 or CuCl2 with NiCl2 and seawater at 3000C. The main series of tests on Cr containing alloys was in a standard solution of 0.1 M NiCl2 for up to 1200 h. Low (1 - 2%) Cr alloys showed initially protective, duplex oxide growth. Subsequently lamination of the inner spinel layer occurred, with the onset of linear corrosion rates which were slower than those of carbon steel. For higher %Cr steels in the standard solution, corrosion rates are approximately two orders of magnitude less than for carbon steel. The oxides were duplex with an inner iron/chromium spinel layer of equal volume to the metal consumed, surmounted by an outer layer of solution deposited magnetite. Oxide morphologies and growth mechanisms are discussed and the implications for PWR steam generator corrosion are analyzed. Recommendations are proposed for maximum seawater levels in steam generator bulk water to avoid long term corrosion damage

290

A Novel Carbon Steel Pipe Protection Based on Radial Basis Function Neural Network  

OpenAIRE

Problem statement: The cost due to corrosion Damage have estimated to be 3-4% of their gross national product which significantly Countries problem around the world. Approach: In this study, a novel carbon steel pipe protection based on RBFNN was proposed. The RBFNN used to predict the minimum current density required in impressed current cathodic protection to protect low carbon steel pipe. Learning data was performed by using a 30 samples test with different concentration C%, temperature T,...

Ajeel, Sami A.

2010-01-01

291

Morphology of protective film formed on steel in aqueous media inhibited with tetrazole  

International Nuclear Information System (INIS)

Surface topography of low-carbon steel after its exposure in water solution of sodium sulfate containing tetrazole as inhibitor, is studied through the methods of screen-electron (SEM) and atom-power (APM) microscopy. The SEM data prove formation of the adsorption phase protection film on the surface of steel samples by their contact with corrosion aqueous media inhibited with tetrazole

292

Effect of Acidified Feronia elephantum Leaf Extract on the Corrosion Behavior of Mild Steel  

Science.gov (United States)

Mild steel is used as a structural material for pipes, tank, reaction vessels, etc. which are known to corrode invariably in contact with various solvents. From the view point of a nation's economy and financial implications of corrosion hazard, it is necessary to adopt appropriate means and ways to reduce the losses due to corrosion. The use of eco-friendly corrosion inhibitors are increasing day by day. Feronia elephantum leaf extract (FELE) has been tested as eco-friendly corrosion inhibitor for A262 mild steel in 1 M H2SO4 and 1 M HCl solutions using non-electrochemical (Gravimetric, X-ray diffraction analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy) and electrochemical techniques (open circuit potential, potentiostatic polarization, and electrochemical impedance measurements). The protection efficiency is found to increase with increase in FELE concentration but decrease with temperature, which is suggestive of physical adsorption mechanism. The adsorption of FELE on mild steel surface obeys the Langmuir adsorption isotherm. SEM results confirm the formation of a protective layer by FELE over mild steel surface.

Muthukrishnan, Pitchaipillai; Prakash, Periakaruppan; Ilayaraja, Murugan; Jeyaprabha, Balasubramanian; Shankar, Karikalan

2015-03-01

293

Effect of long-term aging on electrochemical corrosive behavior of 17-4PH stainless steel  

International Nuclear Information System (INIS)

The corrosion and electrochemical behavior of long-term aging on 17-4PH stainless steel in different solutions has been measured by electrochemical methods. The solutions consisted of chlorine ion sulphuric acid and neutral. Electrochemical potential dynamic reactivation test. The polarization curves results demonstrate that the pitting potential of 17-4PH stainless steel shifted negatively and the protection performance of the passive film decreased after aging treatment. The decline of corrosion resistance of aged specimens ,and with the age time prolonging corrosion inhibitors is decline the sulphuric acid can control the pit corrosion of 17-4PH stainless steel because the vitriol (S) can hold back the Cl-, The anodic polarization curves illustrate that 17-4PH stainless steel can passive in 1% NaCl sulphuric acid, while in 1% NaCl neutral the passivity is deteriorated due to Cl- ion participate in electrochemical corrosion, accelerate the localized corrosion, destroy passivation and induce pit corrosion to the stainless steel. The decline of corrosion resistance of aged specimens was due to the precipitation of the second phase along grain boundaries and the transformation of microstructure. (authors)

294

Trends in the automotive paint industry for corrosion protection  

Energy Technology Data Exchange (ETDEWEB)

Since many years ED-paints are protecting car bodies against corrosion. Currently the automotive paint industry is faced with increasing demands of higher levels of corrosion protection and also requests to comply with new environmental regulations and economical pressures. Some key factors that contributed significantly towards the improvement of corrosion protection systems are: - New generations of lead free ED-paints; - Weldable organic thin film for corrosion protection, especially in box cavities and flange areas. The goal of this paper is to show how the various elements of the 'anti-corrosion package' interact. (authors)

Blandin, Nathalie; Brunat, William [PPG Industries France, 3 Z.A.E. Les Dix Muids, B.P. 89, F-59583 Marly (France); Neuhaus, Ralf [PPG Industries Lacke GmbH, Stackenbergstrasse 34, D-42329 Wuppertal (Germany); Sibille, Ettore [PPG Industries Italia, Via Serra11, I-15028 Quattordio (Italy)

2004-07-01

295

Influence of Processing and Heat Treatment on Corrosion Resistance and Properties of High Alloyed Steel Coatings  

Science.gov (United States)

Corrosion and abrasive wear are two important aspects to be considered in numerous engineering applications. Looking at steels, high-chromium high-carbon tool steels are proper and cost-efficient materials. They can either be put into service as bulk materials or used as comparatively thin coatings to protect lower alloyed construction or heat treatable steels from wear and corrosion. In this study, two different corrosion resistant tool steels were used for the production of coatings and bulk material. They were processed by thermal spraying and super solidus liquid phase sintering as both processes can generally be applied to produce coatings on low alloyed substrates. Thermally sprayed (high velocity oxygen fuel) coatings were investigated in the as-processed state, which is the most commonly used condition for technical applications, and after a quenching and tempering treatment. In comparison, sintered steels were analyzed in the quenched and tempered condition only. Significant influence of alloy chemistry, processing route, and heat treatment on tribological properties was found. Experimental investigations were supported by computational thermodynamics aiming at an improvement of tribological and corrosive resistance.

Hill, Horst; Weber, Sebastian; Raab, Ulrich; Theisen, Werner; Wagner, Lothar

2012-09-01

296

Study on the Corrosion Inhibition Characteristics of Carbon Steel by Sodium Phosphate and Sodium Nitrite  

International Nuclear Information System (INIS)

Sodium nitrite is widely used as one of the popular corrosion inhibitors for the protection of ferrous metal in closed cooling water system, such as a diesel engine and a chiller. The optimum treatment conditions are studied through laboratory tests using linear polarization resistance (LPR) technique. Corrosion rate of the carbon steel electrode could be maintained less than 2.5x10-3 mmpy in the test condition of 500 ppm as NO2-, 200 ppm as CT, 70 .deg. C and pH 6.8. The pH control is confirmed not to be an important factor in the protection of carbon steel by sodium nitrite inhibitor. The addition of tolyltriazole was needed for the protection of the copper alloy in the sodium nitrite treatment system

297

Oil field chemicals synergistic effects on the corrosion rate of L-80 steel in sea and formation waters  

Energy Technology Data Exchange (ETDEWEB)

The corrosion rate of tubular grade L-80 carbon steel under downhole conditions of a northern oil field of Kuwait was investigated. This was done using the injection seawater, formation water and a 50:50 mixture of both waters in the presence of commercially available corrosion inhibitor, scale inhibitor, and biocide products separately and in combination with each other. The main objective of this study was to investigate the effect of the corrosion inhibitor and its interaction with the scale inhibitor and the biocide, as seen in the corrosion rate of L80 carbon steel. This was done using the manufacturers' recommended dosage levels of the corrosion inhibitor, scale inhibitor and biocide. The corrosion rates were measured by linear polarization. Tests were conducted using the rotating cylinder electrode method with rotational speeds of 1000 and 2000 rpm at 80 deg. C. The seawater results indicated that the corrosion-scale inhibitor and biocide-scale inhibitor combinations provided the best protection at both rotation speeds. In formation water, the effects of rotation speed were more apparent with higher corrosion rates of L-80 carbon steel accompanying higher shear forces. In the 50: 50 mix waters and the formation water, the corrosion-scale inhibitors-biocide combination provided the best protection at both rotational speeds under downhole conditions of a northern oil field of Kuwait. (authors)

Al Hashem, A.; Carew, J. [Petroleum Research and Studies Center, Kuwait Institute for Scientific Research, P.O. Box 24885, 13109 Safat Kuwait (Kuwait); Al-Borno, A. [Charter Coating Service (2000) Ltd., no 6, 4604, 13 Street N.E., Calgary, AB T2E 6P1 (Canada)

2004-07-01

298

Effect of Different Treatment on Corrosion Resistance of Sputtered Al Coating on Stainless Steel  

Science.gov (United States)

Aluminum coating on 1Cr18Ni9Ti stainless steel was prepared by magnetron sputtering method. The specimens were treated with pre-oxidation (PO) or vacuum diffusion annealing (VA). Hot corrosion resistance of the coatings beneath the deposits of Na2SO4 at 1050 °C was investigated. Corrosion products were analyzed by XRD and SEM. Results show that the presence of coating could improve the corrosion resistance of stainless steel. FeAl phase appeared after VA at 600 °C, which enhanced cohesive force between the coating and the substrate, and reduced the oxidation and sulfidation rate. PO treatment can protect the substrate more effectively than VA treatment for metastable Al2O3 formed during PO treatment can be translated to stable Al2O3 more quickly at high temperatures. The corrosion products of the two kinds of specimens with aluminum coating were both composed of Al2O3, a little amount of FeS and Fe2O3 after 24 h corrosion. Al2O3 was formed mainly in the coatings, FeS was mainly distributed in the interface between coating and substrate of the specimens, and a small amount of FeS was distributed in the substrate. Al2O3 film remained intact after 24 h corrosion, and kept its protective effect on the substrate.

Fu, Guangyan; Qi, Zeyan; Su, Yong; Liu, Qun; Guo, Xingxing

2014-12-01

299

Stress corrosion cracking of stainless steel used in drill collars  

International Nuclear Information System (INIS)

The present work, studies the stress corrosion cracking behavior in austenitic Fe-Cr-Mn-N stainless steel, in as received, solubilized and sensitized conditions, submitted to several chlorides environments. To evaluate the stress corrosion cracking susceptibility, double cantilever beam specimens, fatigue precracked, side grooved and wedge loaded were used. The environments employed were boiling solution of 45wt.% of MgCl2 at 154 deg. C and synthetic marine environment at ambient and boiling temperature. The susceptibility to stress corrosion cracking has been evaluated in terms of the corrosion stress intensity limit factor, KISCC, applying the fracture-mechanics concept. The results showed that only the specimens in the as received and sensitized conditions, were susceptible to the stress corrosion cracking effect in the boiling solution of 45wt.% of MgCl2 at 154 deg. C, and mean values of the stress corrosion intensity limit factor, KISCC, of 15MPam and 7.8MPam, respectively

300

Corrosion mitigation by photo-catalytic coatings for stainless steels  

International Nuclear Information System (INIS)

Incidents of intergranular stress corrosion cracking (IGSCC) have occurred in boiling water reactors (BWRs) for decades. The electrochemical corrosion potential (ECP) is currently a major indicator for the IGSCC susceptibility of stainless steel (SS) components in BWR environments. This study proposes a novel technique of photo-catalytic treatment to mitigate the IGSCC problems in BWRs that could eventually lead to a lower demand of dissolved hydrogen for hydrogen water chemistry (HWC). Zirconium dioxide (ZrO2) and titanium dioxide (TiO2) were selected as the coating material for corrosion mitigation of Type 304 stainless steel (SS) in high temperature water. Electrochemical polarization analyses were conducted to investigate the corrosion behavior of both treated and untreated samples in 288degC pure water with O2 concentration of 300 ppb. Ultraviolet (UV) irradiation was then imposed upon the treated samples to examine if there was any photoelectric effect on the corrosion behavior of the treated samples. According to the experimental results, the ECPs of the treated samples with UV became lower than those without UV, and the corrosion rates of the treated with UV irradiation were actually lower, as expected. These results indicate that the ZrO2 or TiO2 treatment in combination with UV radiation would effectively reduce the corrosion rate of Type 304 stainless steels in high temperature oxygenated environments. (author)

301

Analysis of corrosion products of carbon steel in wet bentonite  

International Nuclear Information System (INIS)

As a part of evaluation of the long-term durability for the overpack containers for high-level radioactive waste, we have conducted corrosion tests for carbon steel in wet bentonite, a candidate buffer material. The corrosion rates were evaluated by weight difference of carbon steel and corrosion products were analyzed by Fourier transform infrared spectroscopy (FT-IR) and colorimetry. At 40degC, the corrosion rate of carbon steel in wet bentonite was smaller than that in pure water. At 95degC, however, the corrosion rate in wet bentonite was much higher than that in pure water. This high corrosion rate in wet bentonite at 95degC was considered to result from evaporation of moisture in bentonite in contact with the metal. This evaporation led to dryness and then to shrinkage of the bentonite, which generated ununiform contact of the metal with bentonite. Probably, this ununiform contact promoted the local corrosion. The locally corroded parts of specimen in wet bentonite at 95degC were analyzed by Fourier transform infrared microspectroscopy (micro-FT-IR), and lepidocrocite ?-FeO(OH) was found as well as goethite ?-FeO(OH). In wet bentonite at 95degC, hematite ?-Fe2O3 was identified by means of colorimetry. (author)

302

Corrosion of steel tanks in liquid nuclear wastes  

International Nuclear Information System (INIS)

The objective of this work is to understand how solution chemistry would impact on the corrosion of waste storage steel tanks at the Hanford Site. Future tank waste operations are expected to process wastes that are more dilute with respect to some current corrosion inhibiting waste constituents. Assessment of corrosion damage and of the influence of exposure time and electrolyte composition, using simulated (non-radioactive) wastes, of the double-shell tank wall carbon steel alloys is being conducted in a statistically designed long-term immersion experiment. Corrosion rates at different times of immersion were determined using both weight-loss determinations and electrochemical impedance spectroscopy measurements. Localized corrosion susceptibility was assessed using short-term cyclic potentiodynamic polarization curves. The results presented in this paper correspond to electrochemical and weight-loss measurements of the immersed coupons during the first year of immersion from a two year immersion plan. A good correlation was obtained between electrochemical measurements, weight-loss determinations and visual observations. Very low general corrosion rates (-1) were estimated using EIS measurements, indicating that general corrosion rate of the steel in contact with liquid wastes would no be a cause of tank failure even for these out-of-chemistry limit wastes. (author)

303

Electrochemical Evaluation of Corrosion on Borided and Non-borided Steels Immersed in 1 M HCl Solution  

Science.gov (United States)

In this study the corrosion resistances of AISI 1018 and AISI 304 borided and non-borided steels were estimated using polarization resistance and electrochemical impedance spectroscopy (EIS) techniques. Boriding of the steel samples was conducted using the powder-pack method at 1223 K with 6 h of exposure. Structural examinations of the surfaces of the borided steels showed the presence of a Fe2B layer with isolated FeB teeth on the AISI 1018 steel, whereas a compact layer of FeB/Fe2B was formed on the AISI 304 steel. Polarization resistance and EIS of the borided and non-borided steels surfaces were performed in a corrosive solution of 1 M HCl. The EIS data were analyzed during 43 days of exposure to the acid solution. Impedance curves obtained during this period for the borided and non-borided steels were modeled using equivalent electrical circuits. The results of both electrochemical techniques indicated that boride layers formed at the steel surfaces effectively protect the samples from the corrosive effects of HCl. The main corrosion processes observed on the boride layers were pitting and crevice corrosion.

Mejía-Caballero, I.; Martínez-Trinidad, J.; Palomar-Pardavé, M.; Romero-Romo, M.; Herrera-Hernández, H.; Herrera-Soria, O.; Campos Silva, I.

2014-08-01

304

High corrosion resistance of austenitic stainless steel alloyed with nitrogen in an acid solution  

International Nuclear Information System (INIS)

Highlights: ? ASS alloyed with nitrogen treated at 1150 oC exhibits microstructure homogeneity. ? Passivation peak of ASS corresponds to oxidation of metal and absorbed hydrogen. ? Transfer phenomena and conductivity depend on the film formation potential. ? Electronic structure of the passive film and its corrosion resistance correlate well. ? Passive film on ASS with nitrogen is low disordered and high corrosion resistant. - Abstract: Passivity of austenitic stainless steel containing nitrogen (ASS N25) was investigated in comparison with AISI 316L in deareated acid solution, pH 0.4. A peculiar nature of the passivation peak in a potentiodynamic curve and the kinetic parameters of formation and growth of the oxide film have been discussed. The electronic-semiconducting properties of the passive films have been correlated with their corrosion resistance. Alloying austenitic stainless steel with nitrogen increases its microstructure homogeneity and decreases the concentration of charge carriers, which beneficially affects the protecting and electronic properties of the passive oxide film.

305

[Effect of sulfate-reducing bacteria on steel corrosion in the presence of inhibitors].  

Science.gov (United States)

Steel 08KP corrosion was studied as affected by inhibitors in presence of sulphate-reducing bacteria (SRB). Organic compounds, containing functional groups with nitrogen, oxygen and sulphur atoms, were investigated as corrosion inhibitors. It is shown that the studied inhibitors may be divided into three groups as to the mechanism of protective action. It has been established that cation-active nitrogen-containing surfactants ([symbol: see text] X, [symbol: see text]-1, [symbol: see text]-1M, catapin M, [symbol: see text]-2M) are the most efficient steel corrosion inhibitors. Such inhibitors, when adsorbed on metal surface, can affect the process of hydrogen precipitation on its surface, and thus inhibit catalytic function of SRB as the depolarizer of cathode process. PMID:12664553

Purish, L M; Pogrebova, I S; Kozlova, I A

2002-01-01

306

Corrosion resistance of zinc-magnesium coated steel  

International Nuclear Information System (INIS)

A significant body of work exists in the literature concerning the corrosion behaviour of zinc-magnesium coated steel (ZMG), describing its enhanced corrosion resistance when compared to conventional zinc-coated steel. This paper begins with a review of the literature and identifies key themes in the reported mechanisms for the attractive properties of this material. This is followed by an experimental programme where ZMG was subjected to an automotive laboratory corrosion test using acidified NaCl solution. A 3-fold increase in time to red rust compared to conventional zinc coatings was measured. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy were used to characterize the corrosion products formed. The corrosion products detected on ZMG included simonkolleite (Zn5Cl2(OH)8 . H2O), possibly modified by magnesium uptake, magnesium hydroxide (Mg(OH)2) and a hydroxy carbonate species. It is proposed that the oxygen reduction activity at the (zinc) cathodes is reduced by precipitation of alkali-resistant Mg(OH)2, which is gradually converted to more soluble hydroxy carbonates by uptake of atmospheric carbon dioxide. This lowers the surface pH sufficiently to allow thermodynamically for general precipitation of insoluble simonkolleite over the corroding surface thereby retarding the overall corrosion reactions, leaving only small traces of magnesium corrosion products behtraces of magnesium corrosion products behind. Such a mechanism is consistent with the experimental findings reported in the literature

307

Resistance of Cementitious Binders to Chloride Induced Corrosion of Embedded Steel by Electrochemical and Microstructural Studies  

International Nuclear Information System (INIS)

The high alkaline property in the concrete pore solution protects the embedded steel in concrete from corrosion due to aggressive ions attack. However, a continuous supply of those ions, in particular, chlorides altogether with a pH fall in electrochemical reaction on the steel surface eventually depassivate the steel to corrode. To mitigate chloride-induced corrosion in concrete structures, finely grained mineral admixtures, for example, pulverized fuel ash (PFA), ground granulated blast furnace slag (GGBS) and silica fume (SF) have been often advised to replace ordinary Portland cement (OPC) partially as binder. A consistent assessment of those partial replacements has been rarely performed with respect to the resistance of each binder to corrosion, although the studies for each binder were extensively looked into in a way of measuring the corrosion rate, influence of microstructure or chemistry of chlorides ions with cement hydrations. The paper studies the behavior of steel corrosion, chloride transport, pore structure and buffering capacity of those cementitious binders. The corrosion rate of steel in mortars of OPC, 30% PFA, 60% GGBS and 10% SF respectively, with chloride in cast ranging from 0.0 to 3.0% by weight of binder was measured at 7, 28 and 150 days to determine the chloride threshold level and the rate of corrosion propagation, using the anodic polarization technique. Mercury intrusion porosimetry was also applied to cement pastes of each binder at 7 aied to cement pastes of each binder at 7 and 28 days to ensure the development of pore structure. Finally, the release rate of bound chlorides (I.e. buffering capacity) was measured at 150 days. The chloride threshold level was determined assuming that the corrosion rate is beyond 1-2 mA/m3 at corrosion and the order of the level was OPC > 10% SF > 60% GGBS > 30% PFA. Mercury intrusion porosimetry showed that 10% SF paste produced the most dense pore structure, followed by 60% GGBS, 30% PFA and OPC pastes, respectively. It was found that OPC itself is beneficial in resisting to corrosion initiation, but use of pozzolanic materials as binders shows more resistance to chloride transport into concrete, thus delay the onset of corrosion

308

Corrosion testing of stainless steel-zirconium metal waste form.  

Energy Technology Data Exchange (ETDEWEB)

Stainless steel-zirconium (SS-Zr) alloys are being considered as waste forms for the disposition of metallic waste generated during the electrometallurgical treatment of spent nuclear fuel. The waste forms contain irradiated cladding hulls, components of the alloy fuel, noble metal fission products, and actinide elements. The baseline waste form is a stainless steel-15 wt% zirconium (SS-15Zr) alloy. This article presents microstructure and some of the corrosion studies being conducted on the waste form alloys. Electrochemical corrosion, immersion corrosion, and vapor hydration tests have been performed on various alloy compositions to evaluate corrosion behavior and resistance to selective leaching of simulated fission products. The SS-Zr waste forms are successful at the immobilization and retention of fission products and show potential for acceptance as high-level nuclear waste forms.

Abraham, D. P.

1998-12-14

309

Corrosion inhibition of mild steel by aerobic biofilm  

Energy Technology Data Exchange (ETDEWEB)

Mild steel electrodes were incubated in phosphate-buffered basal salt solution (BSS) having two different aerobic bacteria, viz. Pseudomonas alcaligenes and Pseudomonas cichorii. In the medium containing P. cichorii, significant reduction in the corrosion rate was observed due to the surface reaction leading to the formation of corrosion inhibiting bacterial biofilm. With a view to understand the mechanism of microbially influenced corrosion/corrosion inhibition, electrochemical and biological experiments such as electrochemical impedance spectroscopy (EIS) measurements and biochemical analysis were made. The exposed surfaces were examined using scanning electron micrographs (SEM), energy dispersive spectroscopy (EDS) and electron spectroscopy for chemical analysis (ESCA). The scraped surface film was also examined using FT-IR spectroscopy. The results suggested that mild steel surface contained iron oxide-phosphate layer covered with bacteria and exo polymeric substance (EPS)/iron-EPS complex for P. cichorii and iron oxides and iron phosphate for P. alcaligenes.

Chongdar, Shobhana [Naval Materials Research Laboratory, Addl. Ambarnath 421506 (India); Gunasekaran, G. [Naval Materials Research Laboratory, Addl. Ambarnath 421506 (India)]. E-mail: gunanmrl@rediffmail.com; Kumar, Pradeep [Naval Materials Research Laboratory, Addl. Ambarnath 421506 (India)

2005-08-30

310

Corrosion cracking of austenitic Cr-Ni steels and alloys  

International Nuclear Information System (INIS)

The nature of intercrystalline corrosion cracking of austenitic chromium-nickel steels and alloys (1Kh18N9T, 08Kh18N10T, Kh16N15M3B, Kh20N40M5B) is considered for the temperature-time interval preceding the manifestation of intercrystalline corrosion. On the basis of available data the suggestion is made that the intercrystalline corrosion cracking in austenitic steels and alloys, intensified by a temperature increase, an aggressive medium and neutron irradiation, represents an initial stage of ordinary intercrystalline corrosion when chromium-containing phases still remain non-precipitated, but the process of chromium migration starts (the onset of chromium carbides formation) and as this takes place essential structural stresses occur

311

Vapor Corrosion Response of Low Carbon Steel Exposed to Simulated High Level Radioactive Waste  

Energy Technology Data Exchange (ETDEWEB)

A program to resolve the issues associated with potential vapor space corrosion and liquid/air interface corrosion in the Type III high level waste tanks is in place. The objective of the program is to develop understanding of vapor space (VSC) and liquid/air interface (LAIC) corrosion to ensure a defensible technical basis to provide accurate corrosion evaluations with regard to vapor space and liquid/air interface corrosion. The results of the FY05 experiments are presented here. The experiments are an extension of the previous research on the corrosion of tank steel exposed to simple solutions to corrosion of the steel when exposed to complex high level waste simulants. The testing suggested that decanting and the consequent residual species on the tank wall is the predominant source of surface chemistry on the tank wall. The laboratory testing has shown that at the boundary conditions of the chemistry control program for solutions greater than 1M NaNO{sub 3}{sup -}. Minor and isolated pitting is possible within crevices in the vapor space of the tanks that contain stagnant dilute solution for an extended period of time, specifically when residues are left on the tank wall during decanting. Liquid/air interfacial corrosion is possible in dilute stagnant solutions, particularly with high concentrations of chloride. The experimental results indicate that Tank 50 would be most susceptible to the potential for liquid/air interfacial corrosion or vapor space corrosion, with Tank 49 and 41 following, since these tanks are nearest to the chemistry control boundary conditions. The testing continues to show that the combination of well-inhibited solutions and mill-scale sufficiently protect against pitting in the Type III tanks.

Wiersma, B

2006-01-26

312

Mechanical Properties and Corrosion Behavior of Low Carbon Steel Weldments  

OpenAIRE

This research involves studying the mechanical properties and corrosion behavior of ?low carbon steel? (0.077wt% C) before and after welding using Arc, MIG and TIG welding. The mechanical properties include testing of microhardness, tensile strength, the results indicate that microhardness of TIG, MIG welding is more than arc welding, while tensile strength in arc welding more than TIG and MIG.The corrosion behavior of low carbon weldments was performed by potentiostat at scan rate 3mV.sec-...

Mohamed Mahdy; Abdulmajeed, Majid H.; Majed, Rana A.

2013-01-01

313

Corrosion behavior of microwave-sintered austenitic stainless steel composites  

International Nuclear Information System (INIS)

This study compares the electrochemical response of austenitic stainless steel (316L) and yttrium aluminum garnet (YAG)-reinforced 316L composites microwave-sintered in solid-state (1200 deg. C) and supersolidus (1400 deg. C) condition. Compared with conventional sintering (through radiative heating), microwave sintering results in better corrosion resistance. This has been correlated with higher densification and microstructural attributes in the latter. The 316L-5YAG composites consolidated in microwave furnace at 1400 deg. Cyields the highest corrosion resistance

314

Corrosion enhanced erosion of steel in fresh concrete  

OpenAIRE

This paper deals with erosion-corrosion of steel in contact with flowing fresh concrete. Results of tests performed in fresh mortar on rotating cylindrical and disk electrodes are reported. The fresh mortar was manufactured by using chemical admixtures in order to retain constant workability during long time tests. Electrochemical and weight loss tests were conducted. SEM analysis was carried out to evaluate damage morphology. Damage mechanisms and corrosion behavior are discussed. Effect of ...

Cabrini, Marina; Lorenzi, Sergio; Marcassoli, Paolo; Pastore, Tommaso

2010-01-01

315

Influence of anions on the corrosion of high speed steel  

OpenAIRE

Corrosion potential measurements, voltammetric techniques and electrochemical impedance have been used to evaluate the corrosion resistance of M2 high speed steel in aqueous solutions containing chloride, bromide, iodide, nitrate, sulfate and perchlorate salts of sodium and potassium of varying concentration. The influence of changing the cation was found to be small and an order of anion aggressivity was established as: sulfate>chloride>bromide>perchlorate>iodide>nitrate. The data obtained a...

Brett, C. M. A.; Melo, P. I. C.

1997-01-01

316

Localized Surface Modification on 1018 Low-Carbon Steel by Electrolytic Plasma Process and its Impact on Corrosion Behavior  

Science.gov (United States)

Electrolytic plasma process (EPP) was applied on 1018 low-carbon steel sample surfaces and tested in a 3.5% NaCl solution. The treatment details of the EPP were described, and the test results indicate the improvement in corrosion rate, and localized corrosion was due to the unique surface features resulting from the EPP treatment. The corrosion protections show a sustainable consistency for EPP-treated samples in a 48 h immersion test. SEM (with FIB) and XRD were used to characterize the surface features. Potential polarization and cyclic voltammetry were performed for corrosion evaluations.

Liang, Jiandong; Guo, Shengmin; Wahab, Muhammad A.

2014-12-01

317

78 FR 15376 - Determinations: Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea  

Science.gov (United States)

...Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea On the basis of the record...corrosion-resistant carbon steel flat products from Germany and Korea would not be likely to lead...Corrosion-Resistant Carbon Steel Flat Products from Germany and Korea: Investigation Nos....

2013-03-11

318

Bio-corrosion in synthetic and natural sea water of modified stainless steels by poison elements  

International Nuclear Information System (INIS)

In seawater, bacteria can modify the behaviour of stainless steels towards corrosion. It can be then considered to control this type of degradation by a better adjustment of the chemical composition of the steels used. In this work, has been studied the influence of the addition of 'poisons' elements for bacteria on the bio-corrosion resistance of an austenitic 316L steel. The added elements were copper, tin and arsenic. After a bibliographic study and a description of the metallographic, electrochemical and surface analyses methods used, the results obtained in the considered media are given: synthetical seawater, natural, or sterilized and then inoculated. The specific role of each addition elements has then been revealed as well as the alteration of the protecting films and of the induced bio-film, and the behaviour differences in aerobic and anaerobic conditions. (O.M.)

319

On the inhibition of the carbon dioxide corrosion of steel by the carboxylic acids  

International Nuclear Information System (INIS)

The protection effect of the aliphatic carboxylic acids relative to the steels in the liquid and vapor phases of the carbonic media is studied. It is shown, that the efficiency of the carboxylate-type inhibitors increases with the growth of their hydrophoby and their high adsorption ability makes it possible to decay both cathode and anode processes on the steel. The lauric acid is the most effective inhibitor of the carbon dioxide corrosion among the studied carboxylic acids. In spite of the presence of the relatively long alkyl (C11H23) in its molecule it is sufficiently volatile. The caprylic acid in the concentration of 3.7 mmol/l inhibits the steel solution within the temperature range of 30 up to 100 Deg C and increases the effective energy of the corrosion process activation

320

Contribution of acoustic emission to monitor the effect of phosphate based inhibitor on the corrosion behavior of steel reinforcement  

Energy Technology Data Exchange (ETDEWEB)

One of the most important causes of reinforced concrete structures deterioration is the corrosion of the reinforcement steel. This corrosion depends on the presence of aggressive agents such as chlorides in the surrounding medium. Numerous protection techniques have been employed to mitigate this corrosion. Among them, the use of corrosion inhibitors has been considered as one of the most effective solutions. In the present work, the influence of phosphate based inhibitor on the corrosion of reinforcing steels embedded in mortar, and immersed in sodium chloride solution, was investigated by acoustic emission technique. The monitoring of specimens shows that the phosphate based inhibitor addition in the mortar increase the threshold of chloride concentrations, causing the breakdown of steel passivation layer. Thus, the acoustic signatures of concrete fracture and of structure degradation during the corrosion of these specimens have been highlighted. Similarly, the mechanism of phosphate action in terms of preventing steel from corrosion in mortar specimens was analysed by characterization methods (SEM, XRD) of the steel-mortar interface.

Nahali, Haifa [Laboratoire MATEIS CNRS UMR5511 (Equipe CorrIS), INSA-Lyon, Villeurbanne (France); Univ. de Tunis El Manar, Belvedere (Tunisia). Unite de Recherche ' ' Mecanique-Energetique' ' ; Dhouibi, Leila [Univ. de Tunis El Manar, Belvedere (Tunisia). Unite de Recherche ' ' Mecanique-Energetique' ' ; Idrissi, Hassane [Laboratoire MATEIS CNRS UMR5511 (Equipe CorrIS), INSA-Lyon, Villeurbanne (France)

2014-11-01

321

Contribution of acoustic emission to monitor the effect of phosphate based inhibitor on the corrosion behavior of steel reinforcement  

International Nuclear Information System (INIS)

One of the most important causes of reinforced concrete structures deterioration is the corrosion of the reinforcement steel. This corrosion depends on the presence of aggressive agents such as chlorides in the surrounding medium. Numerous protection techniques have been employed to mitigate this corrosion. Among them, the use of corrosion inhibitors has been considered as one of the most effective solutions. In the present work, the influence of phosphate based inhibitor on the corrosion of reinforcing steels embedded in mortar, and immersed in sodium chloride solution, was investigated by acoustic emission technique. The monitoring of specimens shows that the phosphate based inhibitor addition in the mortar increase the threshold of chloride concentrations, causing the breakdown of steel passivation layer. Thus, the acoustic signatures of concrete fracture and of structure degradation during the corrosion of these specimens have been highlighted. Similarly, the mechanism of phosphate action in terms of preventing steel from corrosion in mortar specimens was analysed by characterization methods (SEM, XRD) of the steel-mortar interface.

322

/ Factorial design applied to corrosion of superduplex stainless steel  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish [...] Abstract in english Steels employed in offshore oil and gas production are subject to a very corrosive environment. Especially the new oilfields located in pre-salt layers imply the contact of steels with high brine concentration, high temperature and presence of corrosive gas such as CO2. Besides these facts, stainles [...] s steels have to present higher mechanical properties obtained from an optimized heat treatment. In order to take into account these factors and their synergisms, on the present paper, we have chosen a factorial experimental design to study the corrosion behavior of superduplex steel UNS S32750 by electrochemical tests. The results of open circuit potential, polarization curves and electrochemical impedance were analyzed with statistical methods considering a confidence level of 95%. The factors that significantly affect the corrosion potential are the carbon dioxide and heat treatment; the corrosion current is sensitive to carbon dioxide, and the resistance of polarization is strongly affected by the CO2 content.

T.J., Mesquita; R.P., Nogueira; I.N., Bastos.

2011-10-01

323

Steel corrosion assessment by electrochemical impedance on metakaolin blended mortars  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Since Corrosion of reinforcing steel in concrete is the cause of major economic losses, Portland cement has been traditionally replaced by cements blended with pozzalanic materials, most of which have been found to reduce the corrosion of steel. This paper shows the results of an experimental resear [...] ch aimed to investigate the corrosion of reinforcement in mortar using electrochemical impedance spectroscopy (EIS). For this, concrete laboratory samples containing a 0.0055 m steel bar and prepared with just ordinary Portland cement (OPC) and metakaolin at a replacement level of 20% were analyzed. In order to accelerate the steel corrosion process, all the samples were kept in a 3% NaCl solution and a constant anodic electrical potential was applied. Variations in the water to cementitious material ratio (0.5 and 0.6) and metakaolin proportion were analyzed, while the cementitious material to sand ratio was kept constant at 1:2.25 in all of the specimens. The results showed a reduction in corrosion rates when metakaolin was used as a blending admixture, especially at water to cementitious material ratio of 0.5.

Víctor, Triana; Juan, Lizarazo-Marriaga; Jhon Olaya, Flórez.

1457-14-01

324

Electrochemical and weight-loss study of carbon steel corrosion  

Energy Technology Data Exchange (ETDEWEB)

The Point Lepreau Generating Station (PLGS) will undergo and 18 month refurbishment project beginning in April, 2008. During this time, most of the carbon steel piping in the primary loop will be drained of water and dried. However, some water will remain during the shutdown due to the lack of drains in some lower points in the piping system. As a result, it is necessary to examine the effect of corrosion during the refurbishment. This study examined the effect of several variables on the corrosion rate of clean carbon steel. Specifically, the effect of oxygen in the system and the presence of chloride ions were evaluated. Corrosion rates were determined using both a weight-loss technique and electro-chemical methods. The experiment was conducted at room temperature. The corrosion products from the experiment were analyzed using a Raman microscope. The results of the weight-loss measurements show that the corrosion rate of polished carbon steel is independent of both the presence of oxygen and chloride ions. The electrochemical method failed to yield meaningful results due to the lack of clearly interpretable data and the inherent subjectivity in the analysis. Lepidocricite was found to be the main corrosion product using the Raman microscope. (author)

Thomas, V.J.; Olive, R.P. [Univ. of New Brunswick, Fredericton, New Brunswick (Canada)

2007-09-15

325

Microbial corrosion of high alloy steels in natural sea water  

International Nuclear Information System (INIS)

The paper deals with an investigation into regularities of settlement and potential impact of microbial forms on the corrosion of 12Kh18N10T stainless steel depending on its microstructure. It is shown that inhomogeneity of the morphorological composition and quantitative distribution of microorganisms on the surface of alloyed steels is caused by the selectivity of bacterial cells settlement on the substrate structural elements. The corrosion destruction at microscopic level primarily starts in the zones of microorganism concentration. 19 refs.; 3 figs.; 2 tabs

326

Corrosion of 316L stainless steels MAVL wastes containers  

International Nuclear Information System (INIS)

The long lived and medium activity wastes are conditioned or could be re-conditioned in primary drums of 316L stainless steels. In the framework of wastes storage, these drums will be placed in concrete containers; each containers would contain one or more drums. This document recalls global information on the corrosion of stainless steels, analyzes specific conditions bond to the drums conditioning in concrete containers and the nature of the wastes, and details the consequences on the possible risks of external and internal corrosion of the drums. (A.L.B.)

327

Mitigating Localized Corrosion Using Thermally Sprayed Aluminum (TSA) Coatings on Welded 25% Cr Superduplex Stainless Steel  

Science.gov (United States)

Thermally sprayed aluminum (TSA) coating has been increasingly used for the protection of carbon steel offshore structures, topside equipment, and flowlines/pipelines exposed to both marine atmospheres and seawater immersion conditions. In this paper, the effectiveness of TSA coatings in preventing localized corrosion, such as pitting and crevice corrosion of 25% Cr superduplex stainless steel (SDSS) in subsea applications, has been investigated. Welded 25% Cr SDSS (coated and uncoated) with and without defects, and surfaces coated with epoxy paint were also examined. Pitting and crevice corrosion tests, on welded 25% Cr SDSS specimens with and without TSA/epoxy coatings, were conducted in recirculated, aerated, and synthetic seawater at 90 °C for 90 days. The tests were carried out at both the free corrosion potentials and an applied cathodic potential of -1100 mV saturated calomel electrode. The acidity (pH) of the test solution was monitored daily and adjusted to between pH 7.5 and 8.1, using dilute HCl solution or dilute NaOH, depending on the pH of the solution measured during the test. The test results demonstrated that TSA prevented pitting and crevice corrosion of 25% Cr SDSS in artificial seawater at 90 °C, even when 10-mm-diameter coating defect exposing the underlying steel was present.

Paul, S.; Lu, Q.; Harvey, M. D. F.

2015-02-01

328

Corrosion rate of ferritic ODS stainless steels in a supercritical water environment  

International Nuclear Information System (INIS)

Full text of publication follows: The corrosion behavior of several ODS (Oxide Dispersion Strengthened) steels (Fe-xCryAl-zW-Y2O3) were studied. A corrosion experiment was performed up to 1000 hrs in 510 deg. C and 25 MPa pure water environments. The dissolved oxygen content was controlled by exposing the test solution to laboratory air at the start of the test. The weight gain of each sample was used to estimate the amount of corrosion assuming dissolution rates to be small. Low angle X-ray diffraction method was applied for characterizing the surface oxide resulting from corrosion reactions. further, the cross section area was observed by FESEM-EPMA to reveal the morphology and composition of the oxide. The weight gain increased with time and after a certain time, it reached a steady state. Using the weight gain data, we estimated the corrosion rate defined as the ratio of weight gain and the test interval. The corrosion rate decreased with time, which reflected that the oxide film became protective for all the ODS steels. From XRD and FESEM-EPMA studies, the oxide layers were examined to be Cr rich spinel at the early test period and to become Cr oxide (Cr2O3) after a certain time due to phase transformation. The Cr oxide formation inhibited further corrosion, reaching the steady state. No exclusive aluminum oxide layer was formed in the test condition. Nonetheless, the summation of Cr and Al content represented the corroof Cr and Al content represented the corrosion resistance of ODS steels. (authors)

329

Accelerated hot corrosion studies of cold spray Ni-50Cr coating on boiler steels  

International Nuclear Information System (INIS)

In the current investigation Ni-50Cr powder was deposited on two boiler steels SA-213-T22 and SA 516 (Grade 70) by cold spray process. The hot corrosion performance of coated as well as bare boiler steels was evaluated in an aggressive environment of Na2SO4-60% V2O5 under cyclic conditions at an elevated temperature of 900 oC. The kinetics of the corrosion was approximated by the weight change measurements made after each cycle for a total period of 50 cycles. Each cycle consisted of 1 h heating in a tube furnace followed by 20 min cooling in ambient air. X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDAX) techniques were used to analyse the corrosion products. Both the uncoated boiler steels suffered intensive spallation in the form of removal of their oxide scales, which may be attributed to the formation of unprotective Fe2O3 dominated oxide scales. The Ni-50Cr coated steels showed lesser weight gains and the oxide scales remained intact till the end of the experiment. The phases revealed in the oxide scales of the coated specimens were mainly oxides of chromium and nickel and their spinels which are reported to be protective against the hot corrosion.

330

Effect of liquid metals velocity on corrosion rate of steels  

International Nuclear Information System (INIS)

The nature of liquid-metal coolant velocity on corrosion of steel is considered. The model describing transition from diffusion to kinetic mechanism of liquid metal corrosion under Re number near 105 is proposed, the viscous sublayer plays the main role. The model is suitable for both alkali (Li-Cs, Na+K) and heavy liquid metal (Hg, Bi, Pb, Sn, Ga, Pb+Bi) coolants. It is shown that under velocity variance in wide Re number range various liquid metals have mutual regularities of corrosion rate change

331

Stress corrosion cracking of prestressing steels; Spannungsrisskorrosion an Spannstaehlen  

Energy Technology Data Exchange (ETDEWEB)

During the investigation of a post-tensioned bridge structure incipient cracks of the prestressing steels of the transverse prestressed members were observed. Defects related to non-injected ducts or the presence of corrosion inducing substances could not be detected. The prestressing steel used is a quenched and tempered steel, strength class St 140/160, which was produced in the former GDR. The cause for the cracks is the susceptibility of this type of steel to hydrogen-induced stress corrosion cracking as could be shown in laboratory tests. Under unfavourable conditions cracks can be initiated before grouting. Additional magnetic particle tests at selected areas of the longitudinal prestressed members did not indicate any signs for incipient cracks. (orig.)

Mietz, J.; Fischer, J.; Isecke, B. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany)

1999-09-01

332

Corrosion behaviour of nitrocarburized steels; Korrosionsverhalten nitrocarburierter Staehle  

Energy Technology Data Exchange (ETDEWEB)

Diffusion coatings have been used increasingly to modify surface properties of various machine components for several applications. In general, these coatings are used to improve the wear behaviour. Frequently, it is desirable that the corrosion behaviour will be improved at the same time. In this investigation, the corrosion behaviour of various diffusion coating-substrate-combinations has been studied. The coatings developed by three different nitrocarburizing processes, namely salt-bath, gas and plasma nitrocarburizing, were conducted on five various steel substrates. These substrates were St 52-3, Ck 45, 42 CrMo 4, 30 CrNiMo 8 and X 20 Cr 13. The thickness of the compound layers and their porosity were measured using optical microscopy. The structure of the compound layers was characterized using an X-ray diffractometer and their surface roughness by a stylus profilometer. The corrosion test was carried out using a salt-water spray test. The predominant corrosion mechanisms have been evaluated using scanning electron microscopy. It was found that the employed nitrocarburizing processes have improved the corrosion resistance of all tested coating-substrate-combinations comparing with that of the base materials. In general, the corrosion resistance increases with an increase of the compound layer`s thickness and after an oxidation process. The best coating-substrate-combinations to improve the corrosion behaviour were salt-bath nitrocarburized tempering steels, whereas the thin layers of the plasma nitrocarburized specimens were the worst. (orig.) 12 refs.

Pohl, M.; Al-Rubaie, K.S.; Steinmeier, F. [Bochum Univ. (Germany). Inst. fuer Werkstoffe

1997-06-01

333

Corrosion potential of 304 stainless steel in sulfuric acid  

OpenAIRE

The potentiodynamic study of the electrochemical behavior of austenitic 304 stainless steel in deaerated aqueous sulfuric acid of pH 1 revealed that the steel achieved a stable corrosion potential of ca. – 0.350 V (SCE) independent of whether the electrode had previously been cathodically “activated” or anodically passivated. It was also shown that the experimentally observed anodic peak was not the usually obtained anodic passivation peak, as is the case with a number of metal, but an ...

BORE JEGDIC; Drazic, Dragutin M.; Popic, Jovan P.

2006-01-01

334

Study of Corrosion Behavior of Arc Sprayed Aluminum Coating on Mild Steel  

Science.gov (United States)

In the current study, aluminum coating was deposited on mild steel by arc spraying. A well-adhered coating with low level of porosity was successfully obtained. To evaluate the corrosion behavior of the coating, electrochemical impedance spectroscopy (EIS) and polarization tests in 3.5% NaCl solution were carried out. The as-coated samples were also subjected to a 1500-h salt spray assay. Polarization tests indicated that the corrosion current density of the aluminum coating is more than that of bulk aluminum. This could be due to the penetration of the electrolyte through open pores, resulted in the acceleration of aluminum corrosion. EIS measurements showed that the corrosion performance of the coating is improved during a long time immersion and exposure to saline mist. This could be due to plugging of pores by corrosion products which hinder further penetration of the electrolyte through the coating. The results obtained indicated that twin wire arc sprayed aluminum coatings can reliably protect steel structures against corrosion in chloride-containing aqueous solutions.

Abedi Esfahani, Erfan; Salimijazi, Hamidreza; Golozar, Mohamad A.; Mostaghimi, Javad; Pershin, Larry

2012-12-01

335

Steel corrosion control in highly corrosive wet coalbed methane wells using a passive iron/sulphur complex layer created using organic sulphur salts  

Energy Technology Data Exchange (ETDEWEB)

Water in some coalbed methane (CBM) wells can cause extreme corrosion to steel pipes below the water surface, particularly when it contains high amounts of chlorides, acids or other corrosive components. Current corrosion inhibitor chemicals are not able to handle water that can corrode through steel in 30 days or less. This paper discussed a new approach that has been developed to deal with the problem by creating an iron/sulphur passive layer on the steel portion in order to protect it. Creating this layer is done by adding a solid organic sulphur salt based on carbon disulphide that is water soluble. This salt sinks in the well and evenly distributes its CSB{sub 2B} component to react with the steel to produce the passive layer. The layer protects all steel parts that corrode underneath the water surface without any HB{sub 2B}S generation. It was concluded that there is nearly a six fold reduction in iron loss from standard carbon steel when exposed to 30,000 ppm chloride solution with the potential for a much greater steel lifespan.

Cousins, B.G. [Corrxan Chemicals Ltd., Edmonton, AB (Canada)

2008-07-01

336

The corrosion of steels by hot sodium melts  

International Nuclear Information System (INIS)

Considerable research has been performed by AEA Technology on the corrosion of steels by hot sodium melts containing sodium hydroxide and sodium oxide. This research has principally been in support of understanding the effects of sodium-water reactions on the internals of fast reactor steam generators. The results however have relevance to sodium fires. It has been determined that the rate of corrosion of steels by melts of pure NaOH can be significantly increased by the addition of Na2O. In the case of a sodium-water reaction jet created by a leak of steam into sodium, the composition of the jet varies from 100% sodium through to 100% steam, with a full range of concentrations of NaOH and Na2O, depending on axial and radial position. The temperature in the jet also varies with position, ranging from bulk sodium temperature on one boundary to expanded steam temperature on the other boundary, with internal temperatures ranging up to 1300 deg. C, depending on the local pre-reaction mole ratio of steam to sodium. In the case of sodium-water reaction jets, it has been possible to develop a model which predicts the composition of the reaction jet and then, using the data generated on the corrosivity of sodium melts, predict the rate of corrosion of a steel target in the path of the jet. In the case of a spray sodium fire, the sodium will initially contain a concentration of NaOH and the combustion process will generate Na2O. If there is sufficient humidity, conversion of some of the Na2O to NaOH will also occur. There is therefore the potential for aggressive mixtures of NaOH and Na2O to exist on the surface of the sodium droplets. It is therefore possible that the rate of corrosion of steels in the path of the spray may be higher than expected on the basis of assuming that only Na and Na2O were present. In the case of a pool sodium fire, potentially corrosive mixtures of NaOH and Na2O may be formed at some locations on the surface. This could lead to significant corrosion of any steel structures penetrating the surface, or steel surfaces forming the boundary of the pool. In this paper, the data on the corrosivity of sodium melts containing NaOH and Na2O, as a function of temperature, concentration of each species and velocity of the melt, will be presented for ferritic and austenitic steels and the possible relevance of these data for sodium fires will be discussed. (author)

337

Corrosion behaviour of carbon steel in the Tournemire clay  

International Nuclear Information System (INIS)

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

338

Corrosion behaviour of carbon steel in the Tournemire clay  

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-07-01

339

A liquid aluminum corrosion resistance surface on steel substrate  

International Nuclear Information System (INIS)

The process of hot dipping pure aluminum on a steel substrate followed by oxidation was studied to form a surface layer of aluminum oxide resistant to the corrosion of aluminum melt. The thickness of the pure aluminum layer on the steel substrate is reduced with the increase in temperature and time in initial aluminizing, and the thickness of the aluminum layer does not increase with time at given temperature when identical temperature and complete wetting occur between liquid aluminum and the substrate surface. The thickness of the Fe-Al intermetallic layer on the steel base is increased with increasing bath temperature and time. Based on the experimental data and the mathematics model developed by the study, a maximum exists in the thickness of the Fe-Al intermetallic at certain dipping temperature. X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis reveals that the top portion of the steel substrate is composed of a thin layer of ?-Al2O3, followed by a thinner layer of FeAl3, and then a much thicker one of Fe2Al5 on the steel base side. In addition, there is a carbon enrichment zone in diffusion front. The aluminum oxide surface formed on the steel substrate is in perfect condition after corrosion test in liquid aluminum at 750 deg. C for 240 h, showing extremely good resistance to aluminum melt corrosion

340

Stress corrosion cracking susceptibility of dissimilar stainless steels welded joints  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The aim of the current study is to reveal the influence of welding conditions on structure and stresscorrosion cracking resistance of dissimilar stainless steels butt welded joints.Design/methodology/approach: Butt joints between duplex 2205 and austenitic 316L steels were performedwith the use of submerged arc welding (SAW method. The plates 15 mm in thickness were welded with heatinput in the range of 1.15 – 3.2 kJ/mm using duplex steel filler metal. Microstructure examinations and corrosiontests were carried out. Slow strain rate tests (SSRT were performed in inert (glycerin and aggressive (boiling35% MgCl2 solution environments.Findings: It was shown that place of the lowest resistance to stress corrosion cracking is heat affected zone atduplex steel side of dissimilar joins. That phenomenon was connected with undesirable structure of that zoneconsisted of great amount of coarse ferrite grains and acicular austenite precipitates. High welding inputs do notdeteriorate stress corrosion cracking resistance of welds.Research limitations/implications: High welding heat inputs should enhance the precipitation process ofintermetallic phases in the HAZ. It is necessary to continue the research to determine the relationship betweenwelding parameters, obtained structures, and corrosion resistance of dissimilar stainless steels welded joints.Practical implications: Application of more productive joining process for dissimilar welds like submerged arcwelding instead of currently employed gas metal arc welding (GMAW method will be profitable in terms ofreduction the welding costs.Originality/value: The stress corrosion cracking resistance of dissimilar stainless steel welded joints wasdetermined. The zone of the weaker resistance to stress corrosion cracking was pointed out.

J. ?abanowski

2007-01-01

341

Corrosion of austenitic steel in sodium loops  

International Nuclear Information System (INIS)

The main objective of the work was to investigate whether it is possible to predict corrosion effects with a model based on diffusion laws. The model originates from observed sodium corrosion characteristics. It includes the upstream sodium history as well as the influence of the corroding wall at the considered location. The comparison between the experimental and theoretical results together with the model application to the fuel rod show, that the model is able to predict all characteristics of the sodium austenit corrosion qualitatively correct and to a fairly good degree quantitatively as well. (orig./IHOE)

342

Corrosion behaviour of different hot rolled steels  

OpenAIRE

The oxidation-corrosion behaviour of hot rolled alloys was examined by electrochemical impedance spectroscopy. The corrosion behaviour of the non-oxidised alloys was first determined in order to have a reference behaviour. Then, each alloy was oxidised for 1 and 3 days at 650 degrees C in air and its corrosion behaviour was also determined. For all the alloys, Fe2O3 was formed at the scale-gas interface. However, the Fe2O3 crystallographic structures varied as a function of the alloy composit...

Perez, F. J.; Martinez, L.; Hierro, M. P.; Gomez, C.; Portela, A. L.; Pucci, G. N.; Duday, D.; Lecomte-beckers, Jacqueline; Greday, Y.

2006-01-01

343

Corrosion Inhibition and Adsorption of Anthocleista Djalonesis Leaf Extract on the Acid Corrosion of Mild Steel  

Scientific Electronic Library Online (English)

Full Text Available Aqueous extracts of the leaves of Anthocleista djalonesis (AD) have been investigated as non toxic corrosion inhibitors for mild steel in acidic environments (1 M HCl and 0.5 M H2SO4, respectively). Corrosion rates were evaluated at 30 °C using the weight loss, electrochemical impedance spectroscopy [...] and potentiodynamic polarization techniques. AD extract was found to inhibit mild steel corrosion in both acidic media via adsorption of the extract organic matter on the metal/solution interface. Polarization data indicate that the extract functioned via a mixed inhibition mechanism, affecting both the cathodic and anodic partial reactions of the corrosion process. Molecular dynamics (MD) simulations were performed to illustrate the adsorption process of some specific components of the extract.

C.E., Ogukwe; C.O., Akalezi; M. A., Chidiebere; K.L., Oguzie; Z.O., Iheabunike; E.E., Oguziea.

2012-05-01

344

Flow accelerated corrosion and erosion-corrosion of RAFM steel in liquid breeders  

International Nuclear Information System (INIS)

Corrosion experiments for RAFM, JLF-1 steel (Fe-9Cr-2w-0.1C) in 3types of flowing liquid breeders (i.e. Li, Pb-17Li and Flinak) were performed at the same conditions, and the compatibility was compared with each other. The weight loss of the specimens in the fluids was evaluated by the corrosion model based on mass transfer. The model can be applied to different test systems with different quantity of liquid breeders and different surface area of the systems. The flow enhanced the dissolution of element of the steel in the fluids. The mechanism of an erosion-corrosion in the liquid breeders was the peeling off of the corroded steel surface by the flow. (author)

345

Experimental investigation into corrosion of steels types 20 and 12 Kh1MF in desalinizated water by the weight and electrochemical methods  

International Nuclear Information System (INIS)

The results of studying corrosion of steels 20 and 12Kh1MF under neutral-oxygen and ammonium water chemistry are analyzed. It is shown that chemical corrosion rate exceeds greatly electrochemical corrosion rate and nears it with O2 concentration increase up to 175 mkg/kg due to protective film formation. Iron participating in protective film formation can cause pipeline local corrosion of specific type at the same time. The results of corrosion tests realized by different methods under different conditions are compared

346

Properties of welded joints of corrosion resistant steels, produced by light beam in nitrogen-oxygen mixtures  

International Nuclear Information System (INIS)

Possibilities of weld formation control in Welding corrosion-resistant low-carbon steels by using different by composition nitrogen-oxygen mixtures and assessment of operating properties of welded joints are investigated. It is stated that weld formation under steel welding can be controlled by using nitrogen-oxygen mixtures containing 1-18% oxygen as a protective gas. Fatigue strength and corrosion cracking resistance of welded joints from corrosion-resistant steels conducted in nitrogen-oxygen mixtures exceed these parameters in joints obtained in argon. A possibility of low-carbon steel welding in the air with attaining 0.9-0.92 ultimate strength and 0.45-0.5 plasticity as compared with parameters of the basic metal is disclosed

347

Anti-Corrosive Effect of Tridax Procumbens – Zn2+ System Controlling the Corrosion of Carbon Steel  

OpenAIRE

The corrosion inhibition efficiency (IE) of an aqueous extract Tridax Procumbens(TP) in controlling the corrosion of carbon steel aqueous medium containing 60 ppm of chloride ions in absence and presence of Zn2+ has been studied by weight loss method. The formulation consisting of 1 ml of Tridax Procumbens extract and 150 ppm of Zn2+ offers 96% inhibition efficiency. The synergistic effect exists between Tridax Procumbens and Zn2+ system. Polarization study shows that the Trida...

Kumar, C.; Mohan, R.

2014-01-01

348

Infrared and Raman spectoscopy study, of the corrosion products, on carbon steel and weathering steel  

International Nuclear Information System (INIS)

Infrared and Raman spectroscopy are two analytical tools which have recently been applied to the study of corrosion products formed on metal surfaces. The two techniques are complementary and give structural information similar to that provided by X-ray and electron diffraction. However, they are unlike X-ray and electron diffraction in that they do not require crystalline solids to provide structural identification. Wheathering steels are an important class of metals which form noncrystalline corrosion products. This report describes infrared and Raman spectra obtained from a weathering steel and compares the spectra to those obtained for carbon steel which had been exposed to the same environment

349

Efficiency Criterion of Corrosion Inhibitors of Carbon Steel in Seawater  

Directory of Open Access Journals (Sweden)

Full Text Available A criterion of the efficiency evaluation of corrosion inhibitors of metallic samples in aqueous solutions was proposed for the first time.The criterion was derived based on calculating the limit of ratio value of the resistivity of carbon steel sample in inhibited seawater (?ins to the resistivity of the carbon steel sample in blank seawater (?s. In other words, the criterion; lim (?ins/?s =1 will determine the efficiency of the corrosion inhibitor in the seawater when ?ins becomes equal (decreases to ?s  as a function of time of the exposure of the sample to the inhibited seawater. This criterion is not only can be used to determine the efficiency of different corrosion inhibitors, but also, the criterion can be used to determine the efficiency of corrosion inhibitors with a wide range of concentrations in different aqueous solutions. In addition, the criterion can be applied under diverse test conditions with a predetermined period of inhibitor’s dosages.  Key Words: Efficiency of corrosion inhibitors; Resistivity; Carbon steel; Seawater

K. Habib

2014-01-01

350

Pitting and crevice corrosion of stainless steels in chloride solutions  

International Nuclear Information System (INIS)

In practice stainless steels in chloride containing waters are found to be susceptible to crevice corrosion and pitting. Corrosion tests were carried out on AISI 304 L stainless using a simulated crevice and the compositions of the electrolyte in the crevice determined. Long term potentiostatic tests were used to determine the critical potentials for crevice corrosion (Usub(S)), for various steels in sodium chloride solutions at different concentrations and temperatures. The steels studied were 22 CrMoV 121, X 22 CrNi 17 and AISI 304 L. Like the critical pitting potential (Usub(L)), Usub(S) was found to have a strong dependence on the chloride content of the external solution. At higher concentrations the two potentials were similar. At lower concentrations the Usub(S) was lower than Usub(L). The knowledge of these critical potentials together with well known rest potentials for a steel in an electrolyte of known concentration, allows conclusions to be drawn about its susceptibility to pitting and crevice corrosion. The method is suitable also for other passive metals. (orig.)

351

Corrosion resistance of phosphated steels with plasma sprayed ceramic coatings.  

Czech Academy of Sciences Publication Activity Database

Zagreb : Croatian Metallurgical Society (CMS), 2014 - (Mamuzi?, I.). s. 401 ISBN N. [International Symposium of Croatian Metallurgical Society SHMD 2014/11./. 22.06.2014-26.06.2014, Šibenik] Institutional support: RVO:61389021 Keywords : steel phosphating * phosphate coatings * plasma spraying * ceramic coatings * corrosion resistance * bond strength of coatings Subject RIV: CA - Inorganic Chemistry

Brožek, Vlastimil; Mastný, L.; Pokorný, P.

352

Crude Oil Corrosion Fatigue of L485MB Pipeline Steel.  

Czech Academy of Sciences Publication Activity Database

Ro?. 137, ?. 5 (2015), 051401. ISSN 0094-9930 R&D Projects: GA TA ?R(CZ) TE02000162 Institutional support: RVO:68378297 Keywords : corrosion fatigue * crude oil * pipeline steel * S–N curve * separated water Subject RIV: JI - Composite Materials Impact factor: 0.270, year: 2013 http://pressurevesseltech.asmedigitalcollection.asme.org/article.aspx?articleID=2107675

Gajdoš, Lubomír; Šperl, Martin; Bystrianský, J.

2015-01-01

353

ATMOSPHERIC CORROSION MODEL FOR GALVANIZED STEEL STRUCTURES: EVALUATION AND APPLICATION  

Science.gov (United States)

This report develops a model for predicting the corrosion of galvanized steel structures, based on two competing mechanisms: the formation and dissolution of the basic zinc-carbonate film that forms on zinc surfaces. he model consists of a diffusivity term that describes film gro...

354

Corrosion resistant steel for heat exchangers cooled with aggressive media  

International Nuclear Information System (INIS)

The 04Kh25N6M3B steel is recommended for application instead of titanium and copper-nickel alloys for manufacture of heat exchangers cooled with highly-aggressive media (for example, seawater). This steel is used for production of tubular half finished articles. Forging modes for manufacturing tubular billets as well as technology for hot rolling and cold draining of thin-wall tubes are studied. Technology for welding tubes and tubular billets is also developed. Metallographic examination, corrosion and mechanical tests showed the applicability of the proposed steel for manufacture of heat exchangers

355

Corrosion of Ferritic-Martensitic steels in high temperature water: A literature Review  

International Nuclear Information System (INIS)

Available literature concerning corrosion of high-chromium ferritic/martensitic steel in high temperature water as reviewed. The subjects considered are general corrosion, effect of irradiation on corrosion, environmentally assisted cracking (EAC) including stress corrosion cracking (SCC), corrosion fatigue 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. (Author)

356

Inhibitive Performance of a Rust Converter on Corrosion of Mild Steel  

Science.gov (United States)

In this work, a rust converter consisting of two steps of processing solutions was prepared to convert iron rust of the steel surface into a protective conversion film. The performance of the converter was evaluated in both neutral and acidic solutions by various electrochemical measurements, including potentiodynamic polarization curves and electrochemical impedance spectroscopy, and surface characterization. The effect of temperature was investigated. It was found that the rust converter is able to effectively convert the iron rust into a conversion film, serving as a barrier layer to block corrosive species from reaching the steel surface.

Zhao, X. D.; Cheng, Y. F.; Fan, W.; Vladimir, C.; Volha, V.; Alla, T.

2014-11-01

357

Corrosion resistance properties of sintered duplex stainless steel  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: of this paper was to examine the corrosion resistance of duplex stainless steels using electrochemical methods in 1M NaCl solution. The influence of powder mixes preparation and cooling cycle after sintering on corrosion properties was evaluated.Design/methodology/approach: In presented study duplex stainless steels were obtained through powder metallurgy starting from austenitic, martensitic base powders by controlled addition of alloying elements, such as Cr, Ni, Mo and Cu. In the studies behind the preparation of mixes, Schaeffler’s diagram was taken into consideration. Prepared mixes have been compacted at 800 MPa and sintered in a vacuum furnace with argon backfilling at 1260°C for 1 h. After sintering two different cooling cycles were applied: rapid cooling with an average cooling rate of 245 °C/min and slow cooling of 5 °C/min in argon atmosphere. Produced duplex stainless steels have been studied by scanning and optical microscopy and EDS chemical analysis of microstructure components. Corrosion properties have been studied through electrochemical methods in 1M NaCl water solutionFindings: According to achieved results, it was affirmed that applied sintering method as well as powder mixes preparation allows for manufacturing the sintered duplex steels with good corrosion properties which depends on austenite/ferrite ratio in the microstructure and elements partitioning between phases. Corrosion resistance of sintered stainless steels is strictly connected with the density and the pore morphology present in the microstructure too. The highest resistance to pitting corrosion in 1M NaCl solution was achieved for composition with approximate balance of ferrite and austenite in the microstructure.Research limitations/implications: According to the powders characteristic, the applied fast cooling rate seems to be a good compromise for corrosion properties and microstructures, nevertheless further tests should be carried out in order to examine different cooling rates.Originality/value: The use of elemental powders added to a stainless steel base showed its potentialities, in terms of fair compressibility and final sintered density. In addition a good microstructural homogeneity and first of all corrosion resistance was achieved, also working with cycles possible for industries.

L.A. Dobrza?ski

2006-09-01

358

Corrosion behavior of steels in liquid lead after treatment with intensive pulsed electrons beams  

International Nuclear Information System (INIS)

It is shown that improvement of the corrosion resistance of OPTIFER IVc and 1.4970 steels is achieved by melting and alloying of the surface with intensive pulsed electrons beams. The pulsed electron beam is produced by the GESA device. It is equipped with a cold multi point cathode that provides the beam electrons. Their energy can be varied between 50 and 150 keV. The power density of the electron beam yields up to 2 MW/cm2 at the target surface and covers an area of 30-70 cm2. For the first time, the influence of reflected electrons on the energy deposition during melting of a surface layer is investigated. The magnetic field causes the electrons to be reflected several times between target and the electric field of the accelerator. The resulting changes of the energy deposition are calculated and proved experimentally. The Child-Langmuir equation, which describes the discharge current, is extended by a correction term that considers the back scattered electrons. Aluminum is alloyed into the steel surface up to 15 ?m in depth to improve the corrosion resistance. A 18 ?m thick aluminum foil is placed onto the surface and molten together with the surface steel layer. The aluminum alloys into the molten steel layer with almost constant concentration. The aluminum concentration achieved in the layer amounts to 8-30% depending on the pulse duration of the electron beam. A test stand was build up for the corrosion experiments in which the steel sprosion experiments in which the steel specimens are exposed to liquid lead containing a controlled oxygen concentration. Control of oxygen is employed by adjustment of the H2/H2O ratio in the gas phase. The experiments were carried out with steel samples in as received condition, after surface melting and after alloying of Al into the surface. The maximum exposure time ranged up to 3000 hours. After 3000 hours of exposure a threefold oxide layer is developed on the as received steel surface that protects the steel from the solution attack of liquid lead. The uppermost layer, that grows on the original surface, consists of magnetite. Below the magnetite there is a (Fe, Cr)-spinel layer. The third, innermost layer consists of an oxygen diffusion zone in which oxygen penetrates via the grains and grain boundaries. The intergranular attack of oxygen is strongly reduced in 1.4970 steel by treatment of the surface with the electron beam of GESA. Opposed to this, treatment of OPTIFER IVc steel brings no advantages. Alloying of Al into the surface, however, improves both steel types such that no corrosion attack is observable after 1500 hours of exposure. (orig.)

359

Corrosion, Al containing corrosion barriers and mechanical properties of steels foreseen as structural materials in liquid lead alloy cooled nuclear systems  

International Nuclear Information System (INIS)

A key problem in development of heavy liquid metal cooled nuclear energy and transmutation reactors is the corrosion of structural and fuel. Above 500 oC steels have to be protected by stable, thin oxide scales. A well understood measure is alloying of stable oxide formers into the surface. Two methods, alloying an Al layer into the steel surface using pulsed electron beams (GESA - gepulste Elektronenstrahlanlage) and coating the surface with an Al-alloy with subsequent GESA treatment are applied. In the range of 4-10 wt% Al on the surface a stable thin alumina scale is formed by Al diffusion to the surface and selective oxidation. The alumina scale grows only very slowly and prevents migration of oxygen into the steel as well as migration of steel components onto the surface. A number of corrosion experiments showed the good protective behaviour of Al scales in LBE with 10-6 wt% oxygen up to 650 oC and for exposure times up to 10,000 h. Furthermore the influence of parameters like stresses in the cladding wall, creep behaviour, different flow velocities of the LBE and changing temperatures and oxygen concentrations in LBE is discussed. This paper will provide an overview on the activities concerning Pb-PbBi corrosion and corrosion protection performed at the Institute of Pulsed Power and Microwave Technology (IHM) at the KIT.

360

Corrosion of steel drums containing cemented ion-exchange resins as intermediate level nuclear waste  

International Nuclear Information System (INIS)

Highlights: • There are no works related to the corrosion of drums containing radioactive waste. • Chloride induces high corrosion rate and after 1 year it drops abruptly. • Decrease in the corrosion rate is due to the lack of water to sustain the process. • Cementated ion-exchange resins do not pose risks of corrosion of the steel drums. -- Abstract: Exhausted ion-exchange resins used in nuclear reactors are immobilized by cementation before being stored. They are contained in steel drums that may undergo internal corrosion depending on the presence of certain contaminants. The objective of this work is to evaluate the corrosion susceptibility of steel drums in contact with cemented ion-exchange resins with different aggressive species. The corrosion potential and the corrosion rate of the steel, and the electrical resistivity of the matrix were monitored for 900 days. Results show that the cementation of ion-exchange resins seems not to pose special risks regarding the corrosion of the steel drums

361

Long-Term Underground Corrosion of Stainless Steels  

International Nuclear Information System (INIS)

In 1970, the National Institute of Standards and Technology (NIST) implemented the most ambitious and comprehensive long-term corrosion behavior test to date for stainless steels in soil environments. Over thirty years later, one of the six test sites was targeted to research subsurface contamination and transport processes in the vadose and saturated zones. This research directly applies to environmental management operational corrosion issues and long term stewardship scientific needs for understanding the behavior of waste forms and their near-field contaminant transport of chemical and radiological contaminants at nuclear disposal sites. This paper briefly describes the ongoing research and the corrosion analysis results of the stainless steel plate specimens recovered from the partial recovery of the first test site

362

Long-Term Underground Corrosion of Stainless Steels  

Energy Technology Data Exchange (ETDEWEB)

In 1970, the National Institute of Standards and Technology (NIST) implemented the most ambitious and comprehensive long-term corrosion behavior test to date for stainless steels in soil environments. Over thirty years later, one of the six test sites was targeted to research subsurface contamination and transport processes in the vadose and saturated zones. This research directly applies to environmental management operational corrosion issues and long term stewardship scientific needs for understanding the behavior of waste forms and their near-field contaminant transport of chemical and radiological contaminants at nuclear disposal sites. This paper briefly describes the ongoing research and the corrosion analysis results of the stainless steel plate specimens recovered from the partial recovery of the first test site.

M. K. Adler Flitton; T. S. Yoder

2007-03-01

363

Behavior of aspartic acid as a corrosion inhibitor for steel  

Energy Technology Data Exchange (ETDEWEB)

Corrosion inhibition of steel by aspartic acid (C[sub 4]H[sub 7]NO[sub 4]), an amino acid of low molecular weight, was found to depend strongly on pH. At a pH less than the ionization constant at [approximately]9.5 to 10 (measured at 25 C), C[sub 4]H[sub 7]NO[sub 4] appeared to accelerate corrosion. Above the pH, it acted as a corrosion inhibitor for steel. A specially constructed potential-pH diagram for iron (Fe) that incorporated C[sub 4]H[sub 7]NO[sub 4] showed the change in behavior was accompanied by the most stable thermodynamic state changing from an iron aspartate complex to iron oxide. Polymerized C[sub 4]H[sub 7]NO[sub 4] (polyaspartic acid) behaved in a similar manner. Some other amino acids of low molecular weight behaved similarly.

Kalota, D.J.; Silverman, D.C. (Monsanto Co., St. Louis, MO (United States))

1994-02-01

364

Corrosion behavior of stainless steel-zirconium alloy waste forms  

International Nuclear Information System (INIS)

Stainless steel-zirconium (SS-Zr) alloys are being considered as waste forms for the disposal of metallic waste generated during the electrometallurgical treatment of spent nuclear fuel. The baseline waste form for spent fuels from the EBR-11 reactor is a stainless steel-15 wt.% zirconium (SS-15Zr) alloy. This article briefly reviews the microstructure of various SS-Zr waste form alloys and presents results of immersion corrosion and electrochemical corrosion tests performed on these alloys. The electrochemical tests show that the corrosion behavior of SS-Zr alloys is comparable to those of other alloys being considered for the Yucca Mountain geologic repository. The immersion tests demonstrate that the SS-Zr alloys are resistant to selective leaching of fission product elements and, hence, suitable as candidates for high-level nuclear waste forms

365

Effect of impurities on the corrosion behavior of CO2 transmission pipeline steel in supercritical CO2-water environments.  

Science.gov (United States)

The corrosion property of carbon steel was evaluated using an autoclave under CO(2)-saturated water phase and water-saturated CO(2) phase with impurities (O(2) and SO(2)) at 80 bar CO(2) and 50 °C to simulate the condition of CO(2) transmission pipeline in the carbon capture and storage (CCS) applications. The results showed that the corrosion rate of carbon steel in CO(2)-saturated water was very high and it increased with adding O(2) in the system due to the inhibition effect of O(2) on the formation of protective FeCO(3). It is noteworthy that corrosion took place in the water-saturated CO(2) phase under supercritical condition when no free water is present. The addition of O(2) increased the corrosion rates of carbon steel in water-saturated CO(2) phase. The addition of 0.8 bar SO(2) (1%) in the gas phase dramatically increased the corrosion rate of carbon steel from 0.38 to 5.6 mm/y. This then increased to more than 7 mm/y with addition of both O(2) and SO(2). SO(2) can promote the formation of iron sulfite hydrate (FeSO(3)·3H(2)O) on the steel surface which is less protective than iron carbonate (FeCO(3)), and it is further oxidized to become FeSO(4) and FeOOH when O(2) is present with SO(2) in the CO(2)-rich phase. The corrosion rates of 13Cr steel were very low compared with carbon steel in CO(2)-saturated water environments with O(2), whereas it was as high as carbon steel in a water-saturated CO(2) phase with O(2) and SO(2). PMID:21049923

Choi, Yoon-Seok; Nesic, Srdjan; Young, David

2010-12-01

366

Electrochemical Studies of Stainless Steel Corrosion in Peroxide Solutions  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in english Pollution control measures have resulted in replacement of chlorine by peroxide as bleaching chemical. Change of chemical affects corrosion aspects, the suitability of existing plant metallurgy and materials of construction of bleach plants. Accordingly long term immersion and electrochemical corros [...] ion tests were conducted on stainless steel 304L, 316L, 2205 and 6% Mo and mild steel in peroxide solutions of pH 10. The materials were tested for uniform corrosion, pitting and crevice corrosion and attack around the weld area. Corrosion attack estimated from long term immersion tests is found in agreement, by and large, with that analyzed from electrochemical test. E-pH diagrams drawn for water-peroxide system have been used to understand the corrosivity of the peroxide media. An attempt has been made to suggest a suitable material of construction for handling the test media on the basis of degree of corrosion attack on them and their cost and the mechanical properties.

Ajay K., Singh; Vipin, Chaudhary; A., Sharma.

2012-03-01

367

78 FR 55057 - Corrosion-Resistant Carbon Steel Flat Products from the Republic of Korea: Preliminary Results of...  

Science.gov (United States)

...antidumping duty order on corrosion-resistant carbon steel...effective this date. See Corrosion-Resistant Carbon Steel...Tariff Schedule of the United States (HTSUS). Although...Administrative Review: Corrosion-Resistant Carbon...

2013-09-09

368

A Corrosion Sensor for Monitoring the Early-Stage Environmental Corrosion of A36 Carbon Steel  

OpenAIRE

An innovative prototype sensor containing A36 carbon steel as a capacitor was explored to monitor early-stage corrosion. The sensor detected the changes of the surface- rather than the bulk- property and morphology of A36 during corrosion. Thus it was more sensitive than the conventional electrical resistance corrosion sensors. After being soaked in an aerated 0.2 M NaCl solution, the sensor’s normalized electrical resistance (R/R0) decreased continuously from 1.0 to 0.74 with the extent o...

Dong Chen; Max Yen; Paul Lin; Steve Groff; Richard Lampo; Michael McInerney; Jeffrey Ryan

2014-01-01

369

Investigation of adsorption and corrosion inhibition of mild steel in hydrochloric acid solution by 5-(4-Dimethylaminobenzylidene)rhodanine  

International Nuclear Information System (INIS)

Graphical abstract: The corrosion inhibition of mild steel in 0.5 M HCl solution by 5-(4-Dimethylaminobenzylidene)rhodanine was studied using electrochemical and scanning electron microscopy techniques. The studied organic compound has high inhibitory efficiency against mild steel corrosion in 0.5 M HCl solution. -- Highlights: •The inhibitory effect of DABRh on mild steel corrosion was studied in 0.5 M HCl. •The DABRh acts by reducing the rates of both anodic and cathodic reactions. •The inhibitor film is very stable at low anodic and cathodic overpotentials. •Langmuir adsorption isotherm exhibited the best fit to the experimental data. •The adsorption of DABRh is the mixed type of chemical and physical. -- Abstract: The adsorption and corrosion inhibition of mild steel in 0.5 M HCl solution by 5-(4-Dimethylaminobenzylidene)rhodanine (DABRh) were investigated by electrochemical and scanning electron microscopy (SEM) techniques. It was found that DABRh has high inhibitory efficiency against the corrosion of mild steel in HCl solution. This compound is classified as the mixed type corrosion inhibitor with predominant control of cathodic reaction. The high inhibitory efficiency of DABRh was related with the adsorption of DABRh molecules at the meal/solution interface and a protective film formation. The surface inhibitor film was found to be very stable at low anodic and cathodic overpotentials

370

Corrosion of Aluminized and Uncoated 9-12% Cr Boiler Steels in Simulated Biomass andWaste Combustion Conditions  

Science.gov (United States)

Coatings are seen a promising way to improve the corrosion resistance of relatively cheap power plant steels to enable higher steam temperatures than currently in use. In this research, 9-12% Cr steels P91 and HCM12A are coated with aluminium diffusion coating by a slurry method and exposed for 336 hours at 833 K and 883 K to atmospheres containing varying amounts of O2, H2O, HCl and SO2. Corrosion behaviour of the coated steels is compared to that of those steels in an uncoated condition. Characterization is performed by weighing, SEM + EDS and XRD. The results show that corrosion resistance of P91 and HCM12A is significantly improved by the aluminium diffusion coating at high temperatures in atmospheres containing HCl and SO2. The corrosion rate of the aluminized specimens slightly increases with increase in test temperature but remains virtually the same irrespective of the composition of the atmosphere. On the other hand, the corrosion rate of the uncoated specimens is dependent on both the atmosphere and the temperature. The steels undergo active oxidation that results in formation of non-protective, thick and layered scales in HCl containing atmospheres. SO2 addition slightly decreases the corrosion rate although it is anyway higher than that in SO2 containing atmosphere without HCl.

Metsäjoki, Jarkko; Huttunen-Saarivirta, Elina; Lepistö, T.

2011-04-01

371

Corrosion Protection of Launch Infrastructure and Hardware Through the Space Shuttle Program  

Science.gov (United States)

Corrosion, the environmentally induced degradation of materials, has been a challenging and costly problem that has affected NASA's launch operations since the inception of the Space Program. Corrosion studies began at NASA's Kennedy Space Center (KSC) in 1966 during the Gemini/Apollo Programs with the evaluation of long-term protective coatings for the atmospheric protection of carbon steel. NASA's KSC Beachside Corrosion Test Site, which has been documented by the American Society of Materials (ASM) as one of the most corrosive, naturally occurring environments in the world, was established at that time. With the introduction of the Space Shuttle in 1981, the already highly corrosive natural conditions at the launch pad were rendered even more severe by the acidic exhaust from the solid rocket boosters. In the years that followed, numerous efforts at KSC identified materials, coatings, and maintenance procedures for launch hardware and equipment exposed to the highly corrosiye environment at the launch pads. Knowledge on materials degradation, obtained by facing the highly corrosive conditions of the Space Shuttle launch environment, as well as limitations imposed by the environmental impact of corrosion control, have led researchers at NASA's Corrosion Technology Laboratory to establish a new technology development capability in the area of corrosion prevention, detection, and mitigation at KSC that is included as one of the "highest priority" technologies identified by NASA's integrated technology roadmap. A historical perspective highlighting the challenges encountered in protecting launch infrastructure and hardware from corrosion during the life of the Space Shuttle program and the new technological advances that have resulted from facing the unique and highly corrosive conditions of the Space Shuttle launch environment will be presented.

Calle, L. M.

2011-01-01

372

Chloride induced localized corrosion in simulated concrete pore solution: effect of a phosphate-based inhibitor on the behavior of 304L stainless steel compared to carbon steel  

International Nuclear Information System (INIS)

In this paper, the acoustic emission technique coupled with electrochemical measurements was used to determine, in simulated concrete pore solution (Ca(OH)2), the critical value [Cl-] / [OH-], which prevents the pitting corrosion initiation of AISI 304L austenitic stainless steel, and to compare this critical value with that of the carbon steel in the same medium with and without inhibitor Na3PO4. The results show that for the austenitic stainless steel, the critical threshold of pitting corrosion initiation is around 5, while for carbon steel without inhibitor in Ca(OH)2 solution, it has a low value of about 0.6. However, the presence of the inhibitor Na3PO4 in this solution leads to the formation of a protective phosphate layer on the steel surface, increasing the critical ratio [Cl-] / [OH-] from 0.6 to 15. Under these conditions, the corrosion behavior of carbon steel is improved and, thanks to the blocking of pitting sites by the Na3PO4 inhibitor, it becomes much more resistant to localized corrosion than AISI 304L austenitic steel. (authors)

373

Corrosion of steels in sour gas environments  

International Nuclear Information System (INIS)

This report presents a study on the effects of sour gas environments on steels. Emphasis is placed on alloys commonly used in the heavy water, sour gas and refining industries. In addition, 'high strength, low alloy' steels, known as 'oil country tubular goods', are included. Reference is made to the effects of hydrogen sulphide environments on austenitic steels and on certain specialty steels. Theories of hydrogen-related cracking mechanisms are outlined with emphasis placed on sulphide stress cracking and hydrogen induced cracking in carbon and low alloy steels. Methods of controlling sulphide stress cracking and hydrogen induced cracking are addressed separately. Case histories from the heavy water, refining, and sour gas industries are used to illustrate operating experience and failure mechanisms. Finally, recommendations, based largely on the author's industrial experience, are made with respect to quality assurance and inspection requirements for sour service components. Only published literature was surveyed. Abstracts were made of all references, reviewing the major sources in detail

374

An approach for FGD metallic materials selection and corrosion protection  

Energy Technology Data Exchange (ETDEWEB)

Corrosion was the main cause of poor reliability of early flue gas desulfurization (FGD) components. In order to improve selection of metallic materials for FGD plants, a joint experimental programme has been carried out on corrosion behaviour of candidate materials. The work methodology, experimental programme, and results and conclusions are presented. Stainless steel alloys were assessed; superduplex and superaustenitic steels presented the best behaviour in the most aggressive conditions; corrosion resistance of nickel-base alloys depended on temperature and solution used. Special attention needs to be paid to the welding process and cleaning post-welding. 7 refs., 3 tabs.

Gonzalez, J.F.; Prieto, F.; Gomez-Briceno, D. [ENDESA, Madrid (Spain). Department of Engineering and R& D

1999-11-01

375

Influence of heat treatment on the corrosion of high speed steel  

OpenAIRE

The corrosion behaviour of M2 high speed steel, as-received as well as heat-treated under different conditions, has been studied in 0.1 M KCl aqueous solution by corrosion potential measurements, Tafel curves and electrochemical impedance. Heat treatment leads to an increase of the corrosion resistance of high speed steel; the higher the tempering temperature after quenching, the higher the corrosion resistance of the steel. X-ray diffraction, energy dispersive X-ray analysis and scanning ele...

Alves, V. A.; Brett, C. M. A.; Cavaleiro, A.

2001-01-01

376

Rhenium Uptake as Analogue 96Tc by Steel Corrosion Products  

International Nuclear Information System (INIS)

Static batch experiments were used to examine the sorption of dissolved perrhenate [Re(VII)], as a surrogate for pertechnetate [Tc(VII)], on corrosion products of A-516 carbon steel coupons contacted with synthetic groundwater or dilute water. After 109 days of contact time, the concentration of dissolved Re(VII) in the synthetic groundwater matrix decreased by approximately 26%; the dilute water matrix experienced a 99% decrease in dissolved Re(VII) over the same time period. Bulk x-ray diffraction (XRD) results for the corroded steel coupons showed that the corrosion products consisted primarily of maghemite, lepidocrocite, and goethite. Analyses of the coupons by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) indicated that Re was present with the morphologically complex assemblages of Fe oxide/hydroxide corrosion products for samples spiked with the highest dissolved Re(VII) concentration (1.0 mmol/L) used for these experiments. Analyses of corroded steel coupons contacted with solutions containing 1.0 mmol/L Re(VII) by synchrotron-based methods confirmed the presence of Re sorbed with the corrosion product on the steel coupons. Analyses showed that the Re sorbed on these corroded coupons was in the +7 oxidation state, suggesting that the Re(VII) uptake mechanism did not involve reduction of Re to a lower oxidation state, such as +4. The results of our studies using Re(VII) as an analogue for 99Tc(VII) suggest that 99Tc(VII) would also be sorbed with steel corrosion products and that the inventory of 99Tc(VII) released from breached waste packages would be lower than what is now conservatively estimated

377

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

International Nuclear Information System (INIS)

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

378

Stress corrosion cracking of low steel weldments in LWR environments  

International Nuclear Information System (INIS)

Results obtained at VTT in the ICG-EAC Group bolt-loaded WOL specimen testing round robin for pressure vessel steel weldments in simulated PWR primary water (typical of Loviisa VVER-440 power plant) are presented. Two low alloy type A508 C1.2 steels were tested; one steel had a very low S-content (0.002% S) and the other steel had normal medium S-content (0.008/0.009% S). The low sulphur steel did not show any indication of stress corrosion crack growth, while in one specimen of normal A508 C1.2 steel minor crack extension (less than 1 mm) was locally observed at the precrack tip in the HAZ of the weldment. Crack extension was explained by a water chemistry transient in one phase of the test and the phase of cracking could be related to this occurrence by detailed fractographic examination. Because of difficulties in locating exactly the precrack tip in the HAZ of the weldment, it was observed in the end of the test that precrack tips in various specimens were located either in the weld metal or in the HAZ or in some cases also very close to the fusion line. Thus, this study was also testing the stress corrosion cracking susceptibilities of the various zones of the weldments of low alloy pressure vessel steel A508 C1.2. Stress corrosion crack extension in small amounts was observed only in one HAZ specimen of the normal medium S-content steel

379

Stress corrosion cracking susceptibility of 18 Ni maraging steel  

Science.gov (United States)

The stress corrosion cracking (SCC) resistance of 18Ni maraging steel (grades 200, 250, 300, and 350) was determined in 3.5 percent salt (NaCl) solution, synthetic sea water, high humidity, and outside MSFC atmosphere. All grades of the maraging steel were found to be susceptible to SCC in varying degrees according to their strengths, with the lowest strength steel (grade 200) being the least susceptible and the highest strength steel (grade 350), the most susceptible to SCC. The SCC resistance of 250 grade maraging steel was also evaluated in salt and salt-chromate solutions using fracture mechanics techniques. The threshold value, K sub SCC, was found to be approximately 44 MN/sq m square root m, (40 ksi square root in.) or 40 percent of the K sub Q value.

Humphries, T. S.; Nelson, E. E.

1974-01-01

380

Corrosion properties of stainless steel coatings made by different methods of thermal spraying  

International Nuclear Information System (INIS)

The corrosion protection ability of thermally sprayed stainless steel coatings in aggressive environments is considerably limited as compared to bulk materials of the same composition. The two main reasons for the decrease in corrosion resistance are the porosity in the coatings and the oxidation of elements, particularly chromium, during spraying process. The corrosion resistance and structure of stainless steel coatings, ANVAL 254 SMO, made by different methods of thermal spraying were evaluated in this work. The coatings were produced by atmospheric plasma spraying (APS), atmospheric plasma spraying using gas shielding around the plasma (APS/S), low pressure plasma spraying (LPPS), detonation gun spraying (DGS) and high velocity oxyfuel spraying (HVOF). Electrochemical methods were used for determining the corrosion protection ability of coatings in 3.5% NaCl-solution and in sulfur acid solution (pH 3 and 1). The structure and composition of coatings were studied by optical microscopy and scanning electron microscopy/energy dispersive analysator (SEM/EDS). The porosity of the coatings was determined by water impregnation method, optical microscopy and mercury porosimeter. The results showed that the best coating quality can be achieved by LPPS- and HVOF-coatings. Oxidation and porosity restrict the use of APS-coatings in corrosive environments. The oxidation can be avoided by using argon gas shield around the plasma flame during spraying. Due to porosity all studieuring spraying. Due to porosity all studied coatings suffered crevice corrosion in chloride solution. Despite high Mo-alloying the best coatings reached only the corrosion resistance of AISI 316

381

Stress corrosion cracking of eutectoid steels with progressive cold drawing  

International Nuclear Information System (INIS)

The consequences of the microstructural in an eutectoid steel has undergone a cold drawing process are studied. This manufacturing technique produces changes in the steel microstructure a progressive orientation and slenderizing of the pearlite colonies and an orientation and packing of the pearlite lamellae, thus reducing the inter lamellar spacing. In addition, the experimental results of the stress corrosion cracking tests show that cold drawing produces resistant anisotropy in the steel and thus the stress corrosion cracking resistance is a directional property which seems to depend on the orientation of the microstructure in relation to the cold drawing direction. As a consequence, a transversal crack tends to change its propagation direction approaching the wire axis and a crack growth in mode I evolves to a mixed mode propagation. (Author) 5 refs

382

Preliminary investigations on the corrosivity of PUSPATI's tap water toward different types of steel  

International Nuclear Information System (INIS)

The corrosivity of tap water toward three types of steel has been investigated. It was found that galvanised steels and stainless steels do not experience any significant weight loss after being immersed in tap water for 15 to 30 days. Mild steel, on the other hand, was found to lose 0.34% of its weight after an immersion of 15 days and 0.46% of its weight after 30 days immersion. Water analysis indicates that during the immersion, significant amounts of Fe3+ ions were transferred from the metal surface into the solution. Results of the hardness measurement also suggest that CaCo3 scales which are loosely adhered to the surface of the metal have been formed. However, such layers are of no protective value and were removed during the cleaning of the specimen. (author)

383

Corrosion of low carbon steel in clay and sea sediments  

International Nuclear Information System (INIS)

A serie of corrosion test have been conducted putting in contact mild steel samples with clay and two types of sea sediments. The test have been performed at 30, 50 and 900C up to a maximum duration time of 220 days. As the tests were performed in a closed system, most of the corrosion arrived in anoxic conditions. After an initial stabilization period corrosion weight losses increase linearly with time. The long term corrosion rate in presence of carbonaceous sediments is significantly higher than that obtained in clay or clay rich sediments. An analysis of the ion diffused in the porous media has shown that all the iron which is corroded in the anoxic condition is released in a soluble form. 11 refs

384

Corrosion of two kinds of cast steels containing chromium in hot concentrated alkaline  

OpenAIRE

A typical hot concentrated alkaline corrosion environment exists in alumina metallurgical industry, so that steel materials with outstanding alkaline corrosion resistance are strongly demanded for its processing equipment. In this paper, the corrosion resistance of two kinds of martensitic cast steels containing chromium in static 303g/L NaOH alkaline solution at 85? was studied through polarization and potential-time curves, corrosion weight loss and corrosion morphology analysis. Experime...

Li, Wei; Liu, Jun-quan; Tu, Xiao-hui

2007-01-01

385

76 FR 4291 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Partial Rescission of...  

Science.gov (United States)

...Administration [C-580-818] Corrosion-Resistant Carbon Steel Flat...countervailing duty order on corrosion- resistant carbon steel flat...Steel (Dongbu) and Pohang Iron & Steel Co., Ltd. (POSCO...countervailing duty order on corrosion-resistant carbon steel...

2011-01-25

386

Properties, microstructure and resistance to metal corrosion from pure runoff of supermartensitic stainless steel  

International Nuclear Information System (INIS)

Supermartensitic stainless steels (AISM) are characterized by their very low carbon content, providing good tenacity and weldability. They also contain Ni as a stabilizing agent of the austenite and Mo to improve corrosion resistance. The weldability of these materials is fundamentally important for their applications, mainly in the gas and oil industries. The presence of CO2, H2S, water with a high solids content and condensed water in the production of hydrocarbons together with the large amounts of Cl in these aqueous phases make localized corrosion one of the mechanisms for the degradation of these steels while in service. The protective gases used in the semiautomatic welding process with heavy or tubular wires (GMAW, FCAW) affect the chemical composition of the deposits, particularly the contents of C, O and N, generating variations in their properties. The mechanical properties of these steels are usually optimized after a post-welding heat treatment (PWHT), which may also significantly affect the corrosion resistance of the welding deposits. This work studied the influence of the welding procedure (protective gas and PWHT) on corrosion resistance from pitting of the unalloyed AISM metal. Two test pieces of unalloyed metal were welded according to ANSI/AWS A5.22-95 with a GMAW process using a 1.2 mm diameter tubular wire with metal filling that deposits a supermartensitic stainless steel. The effect of the gas protection was evaluated, welt of the gas protection was evaluated, welding one of the test pieces with Ar- 5%He and the other with Ar-18%CO2. The effect of the PWHT was analyzed, for which samples were extracted from each welded test piece, which were thermally treated at 650oC for 15 minutes, producing as-welded (AW) samples and with PWHT. The chemical composition for both welding conditions was determined. Microstructural characterization was carried out for the four conditions , using optic and scanning electron microscopy and X-ray diffraction, and the Vickers microhardness was determined. Behavior to corrosion from pitting was analyzed in aqueous solutions deaerated for different concentrations of NaCl (0.1; 1 and 2.7 M). Based on the electrodynamic polarization curves obtained the pitting potential for each case was determined, and a statistical analysis was prepared with the results, The protective gas used and the PWHT carried out did not greatly influence the behavior of the deposits to corrosion from pitting. With reference to the influence of the surroundings, heavy dependence occurred with the concentration of CI-, and a logarithmic variation of the pitting potential with the concentration of chlorides was found-+

387

Impact of Desulfovibrio alaskensis biofilms on corrosion behaviour of carbon steel in marine environment.  

Science.gov (United States)

Sulfate reducing prokaryotes are associated with the steel deterioration. They build heterogeneous biofilms, capable of accelerating corrosion processes. In this study metabolic activity and the biofilm development of Desulfovibrio alaskensis were correlated to electrochemical response of carbon steel surface. In the exponential growth phase sulfide concentration reached its maximum of about 10mM. This phenomenon was responsible for the parallel increase in the corrosion potential (Ecorr) up to -720mV (vs. SCE). Subsequently, during the intensive biofilm formation and development another Ecorr peak (-710mV vs. SCE) occurred. Decrease in Ecorr was registered during the biofilm maturation and kept stable, being 20mV lower than in the control. While carbon steel was protected from the microbial attachment and exposed to metabolic products, only one potential maximum (-730mV vs. SCE) was recorded. Here Ecorr variations coincided with sulfide concentration changes and kept at 120mV lower vs. the control. Weight loss examinations revealed corrosion rates, which did not exceed 0.05mm/y. Confocal microscopy suggested the importance of extracellular proteins in the biofilm formation. Above 150 proteins were detected in the EPS matrix. Surface effects of biofilm and metabolic products were visualised, revealing the role of attached microorganisms in the localised corrosion. PMID:24238898

Wikie?, Agata J; Datsenko, Iaryna; Vera, Mario; Sand, Wolfgang

2014-06-01

388

Corrosion of CrN-coated steels for nuclear reactors in liquid Pb-Bi  

International Nuclear Information System (INIS)

Corrosion tests of CrN-coated steels for nuclear reactors were conducted in liquid lead-bismuth (Pb-Bi) at 450degC and 550degC for 3000 h to investigate the applicability of CrN coating to a liquid Pb-Bi environment. CrN coatings on F82H (Fe-8Cr-2W-0.3V-0.04Ta-0.1C) and 316SS exhibited good compatibility in liquid Pb-Bi during corrosion test at 450degC. The CrN coating layer suffered heavy damage such as cracking and spalling, and showed no effectiveness as a protective layer in corrosion test at 550degC. Nickel and chromium in 316SS dissolved into Pb-Bi through the damaged coating layer at 550degC. The cracking and spalling were not found after heating CrN-coated steels in Ar gas at 550degC. It is considered that stresses caused by the difference of thermal expansion coefficients between CrN and steels led to cracking and spalling of the CrN coating through corrosion attack by liquid Pb-Bi at 550degC. (author)

389

The effect of an impinging liquid-solid jet on the electrochemical corrosion of stainless steels  

Energy Technology Data Exchange (ETDEWEB)

Stainless steels rely on their passive film for corrosion protection in saline environments and localised disruption of the passive film can lead to high local rates of material loss. Materials which exhibit passivity in static conditions are often susceptible to erosion-corrosion under severe hydrodynamic regimes. In this paper the corrosion behaviour of two superaustenitic (UNS S31254 and UNS S32654) and one superduplex (UNS S32750) stainless steels was examined in static conditions at a range of temperatures from 18 C to 70 C and during exposure to an impinging saline jet containing varying concentrations of solid particles. In static conditions the materials exhibit decreasing resistance to passivity breakdown as the temperature is increased and a critical breakdown temperature for UNS S31254 and UNS S32750 was identified. Under liquid-solid impingement the materials exhibit an active regime near to the free corrosion potential followed by a stabilised current regime as more positive potentials. The complex electrochemical response is dependent on the material grade and the solid particle concentration. Also in the paper assessment of the 'recovery' of the stainless steels after exposure to slurry impingement is addressed. (orig.)

Hu, X.; Neville, A. [Heriot-Watt Univ., Edinburgh (United Kingdom). Dept. of Mechanical and Chemical Engineering

2001-08-01

390

Mechanical properties and corrosion resistance of dissimilar stainless steel welds  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The purpose of this paper is to determine the influence of welding on microstructure, mechanical properties, and stress corrosion cracking resistance of dissimilar stainless steels butt welded joints.Design/methodology/approach: Duplex 2205 and austenitic 316L steels were used. Butt joints of plates 15 mm in thickness were performed with the use of submerged arc welding (SAW method. The heat input was in the range of 1.15 – 3.2 kJ/mm. Various plates’ edge preparations were applied. Microstructure examinations were carried out. Mechanical properties were evaluated in tensile tests, bending tests and Charpy-V toughness tests. Susceptibility to stress corrosion cracking was determined with the use of slow strain rate tests (SSRT performed in inert (glycerin and aggressive (boiling 35% MgCl2 solution environments.Findings: All tested joints showed acceptable mechanical properties. Metallographic examinations did not indicate the excessive ferrite contents in heat affected zones (HAZ of the welds. It was shown that area of the lowest resistance to stress corrosion cracking is heat affected zone at duplex steel side of dissimilar joins. That phenomenon is connected with undesirable structure of that zone consisted of greater amounts of coarse ferrite grains and acicular austenite precipitates. High heat inputs do not deteriorate mechanical properties as well as stress corrosion cracking resistance of welds.Practical implications: All tested joints showed acceptable mechanical properties. Metallographic examinations did not indicate the excessive ferrite contents in heat affected zones (HAZ of the welds. It was shown that area of the lowest resistance to stress corrosion cracking is heat affected zone at duplex steel side of dissimilar joins. That phenomenon is connected with undesirable structure of that zone consisted of greater amounts of coarse ferrite grains and acicular austenite precipitates. High heat inputs do not deteriorate mechanical properties as well as stress corrosion cracking resistance of welds.Originality/value: Mechanical properties and stress corrosion cracking resistance of dissimilar stainless steel welded joints was determined. The zone of the weaker resistance to stress corrosion cracking was pointed out.

J. ?abanowski

2007-01-01

391

Hydrogen Diffusion and H{sub 2}S Corrosion in Steel  

Energy Technology Data Exchange (ETDEWEB)

The electrochemical permeation technique introduced by Devanathan and Stachurski has been used to measure the effective diffusivity of hydrogen in steel in a H{sub 2}S-saturated aqueous environment. The linear polarization resistance (LPR) method has been used to measure the corrosion rate. The effective diffusion coefficient of hydrogen has been found to be in the range of 1*10-12 to 7*10-11, depending on the environmental conditions. The corrosion film was identified as mackinawite, and it affected the permeation process of hydrogen. The results supported the assumption that the diffusion process can be described by a three layer model and indicated that the model could be reduced to a two layer model in the cases of iron and steel. A model aimed to describe the reaction pathway of hydrogen through the surface film and into the steel is proposed. The corrosion film influenced the corrosion rate, and it was least protective against corrosion at pH 6.5. Corrosion rates were in the range of 0.2-1 mm/year. The corrosion rate was increased significantly at pH 3.5, but the effect of the surface film was stronger and overshadowed the pH effect at the higher pH values. Increased flow velocity also lead to increased corrosion rate, but this effect was less significant compared to the effect of pH and the surface film. DEG decreased the corrosion rate. The uncertainty in the diffusion measurements was mainly due to the assumption of a constant sub-surface concentration of atomic hydrogen, which was not fulfilled. A method less dependent on constant surface conditions would probably yield better estimates of the effective diffusivity. The uncertainty in the corrosion measurements was mainly due to the uncertainty in the value of the Stern-Geary constant. The qualitative assumptions based on the results in this thesis are assumed to be valid. A test section designed for this thesis was tested and was found successful in corrosion rate measurements, but proved to be inadequate for hydrogen diffusion measurements. Other solutions of the diffusion equation and/or other boundary conditions could be considered as an alternative. This could give better estimates of the effective diffusivity and reveal more of the effects of the surface film on the diffusion of hydrogen. (author)

Haugstveit, Bjarte Erlend

2001-01-01

392

Long-term atmospheric corrosion of mild steel  

International Nuclear Information System (INIS)

Research highlights: ? Atmospheric corrosion rate stabilises after the first 4-6 years of exposure. ? Great compaction of the rust layers in rural and urban atmospheres. ? Corrosion (in rural and urban) deviates from common behaviour of bilogarithmic law. ? Typical structures of lepidocrocite, goethite and akaganeite are identified. ? Formation of hematite (industrial atmosphere) and ferrihydrite (marine atmosphere). - Abstract: A great deal of information is available on the atmospheric corrosion of mild steel in the short, mid and even long term, but studies of the structure and morphology of corrosion layers are less abundant and generally deal with those formed in just a few years. The present study assesses the structure and morphology of corrosion product layers formed on mild steel after 13 years of exposure in five Spanish atmospheres of different types: rural, urban, industrial and marine (mild and severe). The corrosion layers have been characterised by X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Long-term corrosion is seen to be more severe in the industrial and marine atmospheres, and less so in the rural and urban atmospheres. In all cases the corrosion rate is seen to decrease with exposure time, stabilising after the first 4-6 years of exposure. The most relevant aspects to be noted are (a) the great compaction of the rust layers formed in the rural and urban atmospheres, (b) the ford urban atmospheres, (b) the formation of hematite and ferrihydrite phases (not commonly found) in the industrial and marine atmospheres, respectively and (c) identification of the typical morphological structures of lepidocrocite (sandy crystals and flowery plates), goethite (cotton balls structures) and akaganeite (cotton balls structures and cigar-shaped crystals).

393

Stress corrosion crack growth rates and general corrosion rates at crack tips of steels in high temperature water  

International Nuclear Information System (INIS)

The maximum stress corrosion crack growth rates for a number of structural materials (steels and nickel alloys) have been measured in 288 C water. Also, the general corrosion rates of these materials have been determined from weight loss experiments in simulated stress corrosion crack tip electrolytes at 288 C. It is shown that the stress corrosion crack growth rates are typically twenty times faster than the general corrosion rates. This correlation holds over five orders of magnitude. It is concluded that strategies to prevent stress corrosion cracking in high temperature aqueous environments might include alloys of higher general corrosion resistance

394

Microbiologically influenced corrosion (MIC) in stainless steel heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

Corrosion attack in the form of corrosion product tubercles was observed in an AISI 304 (EN 1.4301) stainless steel heat exchanger only after 36 months of service. Failure analyses revealed that in one of the attacked areas corrosion had penetrated the entire wall thickness of 6.2 mm, but in most of the cases it reached the depth of 2-4 mm. In this paper, we report the results from a thorough microstructural characterization of the corroded heat exchanger carried out with optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffractometry (XRD). Microstructural studies by OM, SEM and XRD revealed a two-phase structure of austenite and ferrite in the bulk material, as well as the preferential attack of the ferrite phase. SEM surface studies disclosed bacteria in and close to the attacked areas. Cross-sectional SEM examinations showed the distribution and composition of corrosion products within and underneath the tubercles. TEM and XRD studies gave information about the amorphous and/or nanocrystalline nature of some of the formed corrosion products. These results are discussed in this paper and, based on them, the main corrosion mechanism for the observed attack is suggested. Further, explanations for the propagation of corrosion along the ferrite phase are presented.

Huttunen-Saarivirta, E., E-mail: elina.huttunen-saarivirta@tut.fi [Laboratory of Materials Characterization, Department of Materials Science, Tampere University of Technology, P.O.B. 589, FI-33101 Tampere (Finland); Honkanen, M.; Lepistoe, T.; Kuokkala, V.-T. [Laboratory of Materials Characterization, Department of Materials Science, Tampere University of Technology, P.O.B. 589, FI-33101 Tampere (Finland); Koivisto, L. [Andritz Oy, Recovery and Power Division, P.O. Box 184, FI-78201 Varkaus (Finland); Berg, C.-G. [Andritz Pulp and Paper, Tammasaarenkatu 1, FI-00180 Helsinki (Finland)

2012-06-15

395

A shape-recovery polymer coating for the corrosion protection of metallic surfaces.  

Science.gov (United States)

Self-healing polymer coatings are a type of smart material aimed for advanced corrosion protection of metals. This paper presents the synthesis and characterization of two new UV-cure self-healing coatings based on acrylated polycaprolactone polyurethanes. On a macroscopic scale, the cured films all show outstanding mechanical properties, combining relatively high Young's modulus of up to 270 MPa with a strain at break above 350%. After thermal activation the strained films recover up to 97% of their original length. Optical and electron microscopy reveals the self-healing properties of these coatings on hot dip galvanized steel with scratches and microindentations. The temperature-induced closing of such defects restores the corrosion protection and barrier properties of the coating as shown by electrochemical impedance spectroscopy and scanning vibrating electrode technique. Therefore, such coatings are a complementary option for encapsulation-based autonomous corrosion protection systems. PMID:25517028

Lutz, Alexander; van den Berg, Otto; Van Damme, Jonas; Verheyen, Karen; Bauters, Erwin; De Graeve, Iris; Du Prez, Filip E; Terryn, Herman

2015-01-14

396

Corrosion Evaluation and Durability Estimation of Aluminized Steel Drainage Pipes  

Science.gov (United States)

Aluminized steel pipes are expected to have a long service life, e.g. 75 years. Spiral ribbed aluminized pipes (SRAP) have been widely specified and used by the Florida Department of Transportation (FDOT) for drainage of runoff water. Confidence in the long term durability of SRAP has been challenged by recent unexpected early corrosion failures in various Florida locations. SRAP premature corrosion incidents have occurred in two modalities. Mode A has taken place in near-neutral soil environments and has often been associated with either gross manufacturing defects (i.e. helical cuts) or corrosion concentration at or near the ribs. Mode B took place in pipes in contact with limestone backfill and corrosion damage was in the form of perforations, not preferentially located at the ribs, and not necessarily associated with other deficiencies. These failures motivated this research. The objectives of this work are to establish to what extent the Mode A corrosion incidents can be ascribed to manufacturing defects, that can be rectified by appropriate quality control, as opposed to an intrinsic vulnerability to corrosion of regularly produced SRAP due to ordinary forming strains and to determine the mechanism responsible for Mode B corrosion including the role that limestone backfill played in that deterioration. To achieve those objectives, laboratory experiments were conducted to replicate the conditions for Mode A and Mode B. Overall, the findings of this and previous work suggest that much of the corrosion damage observed in the Mode A incidents were promoted more by manufacturing deficiencies and less by any possible inherent susceptibility of corrosion at the ribs of SRAP that was produced following appropriate quality control. Experiments to explore the causes of Mode B corrosion showed that high pH values, sufficient to cause dissolution of the passive film on aluminum, can develop under exposure of limestone to flowing natural water. The findings substantiate, for the first time, an important vulnerability of aluminized steel in limestone soils and provide an explanation for the rapid onset deterioration observed at the field under Mode B. The findings also provide strong evidence in support of service guidelines to disallow the use of limestone bedding for aluminized steel pipe, including SRAP.

Akhoondan, Mersedeh

397

Protective oxide coating on the surface of steel St20  

International Nuclear Information System (INIS)

The authors investigated the stability of oxide coatings on the surface of pearlitic steel 20 at 90 degree C in an aqueous medium. The article examines the influence of the flow rate and of the presence of corrosion products of iron on the protective effect of the oxide coating. On the basis of the results of the investigations obtained with the aid of the radionuclides 59Fe, 54Mn, 137Cs the conclusion is reached that the oxide coating is not restored and does not peel off. The assumption is voiced that a layer of hydroxide forms between the metal and the oxide coating

398

Role of conductive corrosion products on the protectiveness of corrosion layers  

Energy Technology Data Exchange (ETDEWEB)

In the CO{sub 2} corrosion of steels, the bicarbonate ion HCO{sub 3}{sup {minus}} is simultaneously the buffer for carbonic acid, the source of FeCO{sub 3} precipitation and the product of the cathodic reaction. In addition to the spatial separation of the production of Fe{sup ++} and HCO{sub 3}{sup {minus}}, the galvanic coupling between the steel and cementite layers is also the principal cause of internal acidification in these layers, since the HCO{sub 3}{sup {minus}} ions are then removed from the steel surface by electromigration. This can facilitate the initiation of localized corrosion, by lateral galvanic coupling. This mechanism also explains the role of traces of free acetic acid and the existence of multiple steady states. Finally, transposition to the corrosion of iron by H{sub 2}S or to the corrosion of copper is also discussed.

Crolet, J.L. [Elf Aquitaine Production, Pau (France); Thevenot, N.; Nesic, S. [Inst. for Energiteknikk, Kjeller (Norway)

1996-08-01

399

Effect of antimony on the corrosion behavior of low-alloy steel for flue gas desulfurization system  

International Nuclear Information System (INIS)

The alloying effect of Sb in a new low-alloy steel for the purpose of FGD materials was investigated by potentiodynamic polarization, linear polarization resistance measurement, electrochemical impedance spectroscopy (EIS) and weight loss measurements in an aggressive solution of 16.9 vol.% H2SO4 + 0.35 vol.% HCl (modified green death solution) at 60 deg. C, pH -0.3. All measurements confirmed the marked improvement in the corrosion behavior of the low-alloy steel via the addition of a small amount of Sb, particularly for the 0.10Sb steel. Pitting corrosion was detected by scanning electron microscopy (SEM) on the surface of blank steel and 0.05Sb steel, but not 0.10Sb steel, after weight loss measurements. X-ray photoelectron spectroscopy (XPS) analysis of the corroded surfaces after EIS and linear polarization measurements showed that the decrease in corrosion rates was due to the formation of a protective Sb2O5 oxide film on the surface of the Sb-containing steels. Moreover, the addition of 0.10% Sb stimulated the development of high corrosion inhibiting, Cu-containing compounds which further inhibited the anodic and cathodic reactions

400

License plate cosmetic corrosion test of automotive coated steel sheet  

Energy Technology Data Exchange (ETDEWEB)

A new standard laboratory test (SAE J2334) for evaluation of the cosmetic corrosion resistance of autobody steel sheet has been developed through the joint efforts of the Society of Automotive Engineers Automotive Corrosion Prevention Committee (SAE/ACAP) and the Auto/Steel Partnership (A/SP) Corrosion Task Force. Results from this test gave an excellent correlation with those of on-vehicle tests conducted for 5 years in Canada at St. John`s, Newfoundland, and Montreal, Quebec. To determine how results of the Canadian tests related to environments in the United States, racks of identical materials were mounted on the front license plate brackets of cars driven in various locations in the US snowbelt, including Bethlehem, Pennsylvania; Detroit, Michigan, and Chardon, Ohio. After 4 years to 5 years, these tests showed the US environments produced less scribe creep and more red rust than those conducted in Canada. Similar rankings were obtained for the scribe creep resistance of the various coated steel sheet products when compared at equivalent amounts of corrosion. However, the ranking of materials changed at longer exposure times in Canada, and for that reason, it was concluded that the 5-year Canadian results used in the development of the SAE J2334 test provided a better real-world performance standard.

Townsend, H.E. [Bethlehem Steel Corp., Bethlehem, PA (United States)., Homer Research Labs.; Simpson, M.W. [PPG/Chemfil Corp., Troy, MI (United States). Coatings and Resins Group; Linde, W.B. van der [E.I. DuPont de Nemours and Co., Inc., Philadelphia, PA (United States). Automotive Products Development; McCune, D.C. [Quality/Statistics, Beaver, PA (United States)

1999-04-01

401

Stress corrosion cracking evaluation of martensitic precipitation hardening stainless steels  

Science.gov (United States)

The resistance of the martensitic precipitation hardening stainless steels PH13-8Mo, 15-5PH, and 17-4PH to stress corrosion cracking was investigated. Round tensile and c-ring type specimens taken from several heats of the three alloys were stressed up to 100 percent of their yield strengths and exposed to alternate immersion in salt water, to salt spray, and to a seacoast environment. The results indicate that 15-5PH is highly resistant to stress corrosion cracking i