WorldWideScience
1

Corrosion and anti-corrosion protection of steel structures  

OpenAIRE

The thesis provides the basics about corrosion of steel structures. It describes different perspectives on genesis of corrosion – engineering, physics, chemistry and electrochemistry perspective, and what promotes its development. Next chapter is about anti-corrosion protection, actually it considers four methods of steel defense. The methods are: chatodic protection, electroplating or galvanization, because I am focused on steel structures, anti-corrosion paint coatings and protection with...

Kovac?ic?, Mateja

2012-01-01

2

AC corrosion on cathodically protected steel  

OpenAIRE

This report deals with the effect of alternating current on cathodically protected steel. AC corrosion has become relevant in the offshore industry due to the introduction of the direct electric heating system (DEH). The principle with DEH is to prevent wax solidification inside pipelines by heating them up with alternating current. This can give rise to AC corrosion.DC current densities, AC current densities and DC potential have been measured for steel samples under cathodic protection with...

Torstensen, Andreas

2012-01-01

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

Electric corrosion protection method for steel material  

International Nuclear Information System (INIS)

A semiconductor having a thermoelectric performance of 920?V/K or more is incorporated between a steel material of a light water reactor to be in contact with high temperature water and an aqueous solution. This shifts the corrosion potential of the steel material in a high temperature water to more basic side. Satisfactory corrosion resistant metal silicate, for example, FeSi2 is preferably used for the thermoelectric semiconductor. Co is added to FeSi2 to form an n-type semiconductor. A layer of Si3N4 is formed to the circumference of a cylindrical FeSi2 to form an insulation layer. This member is disposed to a hole bored to a stainless steel pipe, and the one surface is brought into contact with high temperature water on the inner side of the stainless steel. On the other side in contact with the outer atmosphere is bonded to the outer surface of the stainless steel pipe by a lead wire. Since the n-type semiconductor has a positive potential on the side at a higher temperature, the potential of the stainless steel is determined to negative. (I.N.)

5

ANTI-CORROSION AND FIRE PROTECTION OF STEEL STRUCTURES  

OpenAIRE

The thesis discussed the problem of how to protect steel structures against corrosion and fire. Because of the scale selected topics we focused our work on the basics of the problem. First of all, we describe in section two of the thesis what corrosion is, how they arise and present types of corrosion. Also in this section we present the process of preparing the surface of steel structures, the selection of an appropriate protective coating as well as type of application method and finally th...

Ragolic?, Sandy

2012-01-01

6

Stainless steel structures and corrosion protection of steel structures according to Eurocode  

OpenAIRE

Steel is an excellent material to build with, but consideration must be given to the fact that unprotected steel corrodes, rusts, therefore, as a rule, the steel must be protected in some way. This can be done by reducing the tendency of the steel to corrode by using stainless steel or by treating the steel with a protection method. The two most common methods of protection are corrosion protection paint and zinc coating. To determine the method, the corrosive category must first be evaluated...

Karlsson, Niklas; O?jemyr, Jenny

2012-01-01

7

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)

9

Investigation of Corrosion and Cathodic Protection in Reinforced Concrete. II: Properties of Steel Surface Layers:  

OpenAIRE

The present study explores the formation of corrosion products on the steel surface (using as-received low carbon construction steel) in reinforced concrete in conditions of corrosion and subsequent transformation of these layers in conditions of cathodic protection (CP).

Koleva, D. A.; Wit, J. H. W.; Breugel, K.; Lodhi, Z. F.; Ye, G.

2007-01-01

10

Corrosion protection of mild steel by a calcite layer  

Energy Technology Data Exchange (ETDEWEB)

Artificial calcite lining represents a novel technique for the rehabilitation of water mains. Calcite linings, similar to the commonly used cement-mortar linings, are of porous nature. The corrosion protection mechanisms of calcinite linings were investigated by polarization techniques, complemented by scanning electron microscopy observations and energy dispersive spectrometry analyses. The effect of time on lining durability was examined by exposure of coated mild steel (1020) coupons in a controlled flowing water system. Iron ion distributions in calcite sections, before and after exposure to water flow, indicate that the calcite corrosion protection mechanism is based mainly on accumulation of corrosion products inside the lining. At the calcite-metal interface, a protective film is formed. At the calcite-water interface, the calcite structure, being alkaline with respect to the water, promotes precipitation of the iron ions and blockage of the pores near that interface. The formation of this protective oxide film was evident from the polarization data which showed that both the anodic Tafel constant and the polarization resistance increase with time. This paper also examines the applicability of potentiodynamic and linear polarization techniques for the characterization of the corrosion protection of a porous lining, such as calcite. It is shown that these convenient electrochemical techniques provide reliable and meaningful corrosion protection information.

Keysar, S.; Hasson, D.; Semiat, R.; Bramson, D. [Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Chemical Engineering

1997-08-01

11

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

12

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

2015-01-01

13

Corrosion Protection of Hot Dip Galvanized Steel in Mortar  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in english Corrosion of steel in concrete is one of the major causes of structure degradation, requiring expensive maintenance. The using of hot dip galvanized steel (HDGS) has been recognized as one effective measure to increase the service life of reinforced concrete structures in marine environmental. Howev [...] er, HDGS corrodes in contact with high alkaline environment of fresh concrete. Although this initial corrosion process allows the formation of a protecting layer barrier, the corrosion that occurs initially is harmful and chromate conversion layers are usually used to prevent it. Due to toxicity of Cr(VI), these kinds of pre-treatments have been forbidden and hybrid coatings have been proposed as alternatives [1-3]. To evaluate the performance of these coatings, beyond the laboratory characterization, in situ tests in real conditions should be performed. An electrochemical system to measure the macrocell current density (i gal) was designed to evaluate the degradation of HDGS coated samples with different organic-inorganic hybrid films, embedded in mortar during 70 days, using an automatic data acquisition system. This system revealed to be feasible and highly sensitive to coatings degradation. Also, allow distinguishing different hybrid coatings with different thicknesses.

Rita M., Figueira; Elsa V., Pereira; Carlos J.R., Silva; Maria M., Salta.

2013-10-08

14

Corrosion protection of galvanized steels by silane-based treatments  

Science.gov (United States)

The possibility of using silane coupling agents as replacements for chromate treatments was investigated on galvanized steel substrates. In order to understand the influence of deposition parameters on silane film formation, pure zinc substrates were first used as a model for galvanized steel to study the interaction between silane coupling agents and zinc surfaces. The silane films formed on pure zinc substrates from aqueous solutions were characterized by ellipsometry, contact angle measurements, reflection absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscopy. The deposition parameters studied include solution concentration, solution dipping time and pH value of the applied solution. It appears that silane film formation involved a true equilibrium of hydrolysis and condensation reactions in aqueous solutions. It has been found that the silane film thickness obtained depends primarily on the solution concentration and is almost independent of the solution dipping time. The molecular orientation of applied silane films is determined by the pH value of applied silane solutions and the isoelectric point of metal substrates. The deposition window in terms of pH value for zinc substrates is between 6.0 and 9.0. The total surface energy of the silane-coated pure zinc substrates decreases with film aging time, the decrease rate, however, is determined by the nature of silane coupling agents. Selected silane coupling agents were applied as prepaint or passivation treatments onto galvanized steel substrates. The corrosion protection provided by these silane-based treatments were evaluated by salt spray test, cyclic corrosion test, electrochemical impedance spectroscopy, and stack test. The results showed that silane coupling agents can possibly be used to replace chromates for corrosion control of galvanized steel substrates. Silane coatings provided by these silane treatments serve mainly as physical barriers. Factors that affect the performance of a silane coupling agent in the application of corrosion control include chemical reactivity, hydrophobic character, siloxane crosslinker network, and film thickness. Good protections afforded by the silane treatments are a synergetic effect of all these factors.

Yuan, Wei

15

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

16

Physicochemical foundation of steel protection against sulfide corrosion cracking  

International Nuclear Information System (INIS)

Essentially new notions on physical-chemical mechanism of hydrogen absorption and steel sulfide corrosion cracking are formulated. The quantitative evaluation of various factors impact (the nature of chemical process on the steel surface, temperature, hydrogen sulfide partial pressure in the working medium) on hydrogen content in the steel and consequently on its tendency to cracking is accomplished within the frames of these notions. 12 refs.; 1 fig.; 1 tab

17

Corrosion cracking and protection of welded structures made of low-carbon and low alloy steels  

International Nuclear Information System (INIS)

The factors conditioning corrosion cracking of low-carbon steels and their welded joints in alkali, carbonate, phosphate, hydrogen sulfide solutions and in ammonia are considered. In all cases formation of corrosion cracks proceeds under conditions of active-passive transfer, whereby electrochemical reactions result in generation of protons after discharge, whereof the metal absorbed hydrogen. The role of hydrogen by corrosion cracking of construction welded steels in the considered media is expressed in a different degree. The ways of welded joints protection against corrosion cracking in the given metal-medium systems, the role of alloying and admixture elements and structural state of steels are analyzed

18

The application of thermal spraying for corrosion protection of large steel parts used in special buildings  

International Nuclear Information System (INIS)

An aluminium spraying procedure is presented for obtaining high-quality long-life corrosion protection for large steel parts used in special buildings in nuclear power plant construction. The advantage of a stationary metal arc spraying installation in the prefabrication of the steel parts is described. At the erection site field welds have to be metal sprayed

19

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

Energy Technology Data Exchange (ETDEWEB)

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: Black-Right-Pointing-Pointer Organic layers for corrosion protection of 304 stainless steel (SS) surface. Black-Right-Pointing-Pointer Bio-inspired self assembly of polydopamine/composite films. Black-Right-Pointing-Pointer 6-aminohexanol membrane synthesized on polydopamine modified SS surface. Black-Right-Pointing-Pointer An efficiency route for improving corrosion protection.

Yu Fei [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Chen Shougang, E-mail: sgchen2000@yahoo.com.cn [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Li Houmin; Yang Lejiao [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Yin Yansheng [Institute of Marine Materials Science and Engineering, Shanghai Maritime University, Shanghai 200135 (China)

2012-05-31

20

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

21

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

22

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

23

Use of coatings to protect steels against lead corrosion at high temperatures  

International Nuclear Information System (INIS)

Adequately adhering coatings are described, as is the structure of thermal sprayed layers. Adhesion to the base metal and the four binding mechanisms on which it is dependent are described. The criteria for selecting the coating materials is described and the results tabulated. Corrosion tests are described with micrographics and examples explained. Conclusions include the finding that the production of high-quality composites resistant to liquid lead corrosion is made possible by thermal-spraying protective layers on high temperature steels

24

Corrosion-protection of cold-rolled steel by plasma-polymerized films  

Energy Technology Data Exchange (ETDEWEB)

Thin films (about 500 {angstrom}) of RF plasma-polymerized hexamethyldisiloxane and trimethylsilane were deposited on cold-rolled steel coupons after cleaning in solvents and in reactive or non-reactive plasmas. The focus of this project was on the corrosion protection afforded by such films with special emphasis on the correlation between the corrosion performance and the film deposition conditions, including the type of steel pretreatment. Corrosion was determined in a standard humidity test. The performance in this test was compared with Electrochemical Impedance Spectroscopy data on the same films. Morphology and compositional studies by SEM, AES and TOFSIMS were also carried out. The performance of the films varied widely and depended strongly on the type of pretreatment and the rate and power of film deposition. The presence of powder inclusions in the films was found to have a particularly strong negative effect on the corrosion performance of the films. Results and mechanistic interpretations will be presented.

Conners, K.D.; Clarson S.J. [Univ. of Cincinnati, OH (United States); Ooij, W.J. van; Sabata, A. [Amco Research & Technology, Middletown, OH (United States)

1993-12-31

25

Increasing corrosion-fatigue strength of steels in salt water by using the protective silicazinc-2 paint  

International Nuclear Information System (INIS)

The possibility to increase the corrosion fatigue strength of steels in sea water due to protective paint ''Silicazink'' was investigated. Fatigue test was carried out by console bending of flat painted steel specimens (st.3 and 45 G17Yu3). The study has shown that the protective paint essentially increases workability of steel. The fatigue strength of specimens painted according to the scheme using ''Silicazink'' is 19% greater than the one of specimens painted according to a regular scheme. Inhibited oxidation of zink filler in ''Silicazink'' results in increase of protective sub-layer life-time and corrosion fatigue strength of steel specimens protected by combined coatings

26

Corrosion protection properties of hydroxamic acid self-assembled monolayer on carbon steel  

International Nuclear Information System (INIS)

Self assembled monolayers (SAMs) of hydroxamic acids CH3(CH2)nCONHOH with different alkyl length were formed on the carbon steel electrode surface. The corrosion protection properties of the monolayers were examined and characterized by electrochemical polarization curves, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy (XPS) and contact angle measurements. XPS results showed that the hydroxamic acid molecules adsorbed on the carbon steel surface, and the contact angle values on the modified surface supported the formation of hydrophobic hydroxamic acid SAMs. The results of electrochemical studies showed that the values of the corrosion potential shift towards the positive direction, and anodic currents of the carbon steel dissolution significantly decreases, indicating that hydroxamic acids are anodic inhibitors. However, the chain length and assembling time influence the protection efficiency

27

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

28

A polyaniline based intrinsically conducting coating for corrosion protection of structural steels.  

Science.gov (United States)

Among the various corrosion protection strategies for structural steels, coating techniques provide the most cost-effective protection and have been used as the primary mode of corrosion protection. Existing coating techniques however have been used mainly for their barrier capability and therefore all have a limited service life due to oxidation aging, electrolytic degradation, or various inadvertent defects and flaws occurred in and after coating applications. This work investigated the anti-corrosion potential of a ?-conjugated polymer-polyaniline (PANi), which was doped into an intrinsically conducting polymer and then included in a two-layer coating system as a primer layer. To achieve a long service life, the primer layer was made by mixing the conductive PANi in a waterborne poly-vinyl butyral solution to provide strong adhesion to steel surface, and then topcoated with a layer of elastomer-modified polyethylene to obtain extra mechanical and barrier protections. Two ASTM standard tests were conducted to evaluate the corrosion durability and tensile adhesion of the two-layer system, in which the system demonstrated superior performance. The Scanning Kelvin Probe Force Microscopy (SKPFM) was used to provide the microscopic evidences for the outstanding performance. PMID:24000080

Pan, Tongyan; Wang, Zhaoyang

2013-11-01

29

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

30

Polybenzoxazine/SiO2 nanocomposite coatings for corrosion protection of mild steel  

International Nuclear Information System (INIS)

Highlights: •Corrosion resistance of the coating was improved using SiO2 nanoparticles. •Morphology and wetting properties were studied upon electrochemical behavior. •Interfacial interactions were enhanced by the reaction between two phases. -- Abstract: A series of nanocomposite coatings (PBS) consisting of silane functional polybenzoxazine (PB-TMOS) and SiO2 nanoparticles were developed for corrosion protection of mild steel. The influence of silica content on corrosion resistance of PBS coatings was investigated by electrochemical measurements. The surface chemistry of nanoparticles and its effect on morphology of the PBS coating was also studied utilizing Fourier Transforms Infrared Spectroscopy, 29Si Nuclear Magnetic Resonance and Scanning Electron Microscopy analyses. The results indicate that the presence of the covalent bond between nanoparticles and PB-TMOS, greatly improves the interfacial interactions at the polymer/filler interfaces resulting in a better corrosion performance

31

Prevention of crevice corrosion in duplex SS flanges using carbon steel bolts with cathodic protection  

Energy Technology Data Exchange (ETDEWEB)

Achieving reliable long-term performance of high strength bolts for flange connections in subsea service is a critical issue for the offshore industry. Viable bolting materials with high strength that are not susceptible to embrittlement or galvanic corrosion when the flanges are made of stainless steels are limited. A laboratory study was performed to determine the viability of using B7 carbon steel stud bolts and 316 stainless steel (SS) seal rings in a Duplex SS flange for subsea service The laboratory test system used full size commercial flanges, bolts and seal rings to simulate electrochemical conditions that will occur in crevices associated with carbon steel bolts in a Duplex SS flange and with the use of a 316 stainless steel seal ring in a Duplex SS flange. The flange systems were instrumented to enable monitoring of current densities and potentials at precise locations within the crevices throughout the tests as test parameters were changed. Test parameters included cathodic protection level, temperature, and sealing the outer flange gap. Cathodic protection was provided by remote aluminum sacrificial anodes to achieve potentials typical for a sub sea manifold. Both electrochemical data and examination of the components at the end of the 164 day exposure indicated that sufficient cathodic protection occurred in the crevices to provide long term corrosion control to all of the components involved. The capability to use B7 bolts rather than high alloy bolts enables a significant project savings.

Thomason, W.H.; Ivie, R.G.; Marlow, J.A.

1999-07-01

32

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

33

Electrodeposition of Zn-Ni coatings as Cd replacement for corrosion protection of high strength steel  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: {yields} Electrodeposition of Zn-Ni coatings from an alkaline bath on a high strength steel. {yields} Complete characterisation of the coatings (corrosion, morphology and composition). {yields} Correlation of the electrodeposition conditions with the properties of the film. {yields} Similar corrosion resistance than Zn-Ni coatings deposited from acidic baths. {yields} Lower hydrogen content incorporated than for a post baked cadmium-coated steel. - Abstract: Electrodeposition of Zn-Ni coatings performed in acidic baths are not suitable for high strength steels due to their high susceptibility to hydrogen embrittlement. In this work, Zn-Ni coatings were deposited on a high strength steel (4340) upon stirring conditions from an alkaline bath. A complete characterisation of the coatings (corrosion, morphology and composition) has been accomplished, correlating the electrodeposition conditions with these features. The best protective properties of the grown coatings were achieved for the alloys with a single phase structure of {gamma}-Ni{sub 5}Zn{sub 21} and a denser morphology. Additionally, the hydrogen content incorporated is lower than even cadmium-coated 4340 steel which has undergone a postbaking dehydrogenation treatment.

Conde, A., E-mail: a.conde@cenim.csic.e [Dpto.Corrosion y Proteccion, Centro Nacional de Investigaciones Metalurgicas (CENIM-CSIC), Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Arenas, M.A.; Damborenea, J.J. de [Dpto.Corrosion y Proteccion, Centro Nacional de Investigaciones Metalurgicas (CENIM-CSIC), Avda. Gregorio del Amo, 8, 28040 Madrid (Spain)

2011-04-15

34

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)

35

On the inhibitor protection of high-strength steels from corrosion cracking on the crack propagation stage  

International Nuclear Information System (INIS)

Possibilities of applying inhibitors to protect high-strength steels from corrosion crack growth in water medium, are studied. Mechanisms of their effect are investigated. Tests are carried out using the heat treated 45KhN2MFA steel (tempering 200 deg C) at the temperature of 25 deg C using beam samples (12x18x160 mm). It is shown that inhibitor protection of high-strength steels from corrosion cracking is a prospective way of increasing their corrosion crack resistance. Oxoanions are inhibitors of crack growth if they are reduced during adsorption, absorbing hydrogen ions. Inhibitors of the ICG type (inhibitors of crack growth) which suppress the process of hydrogen discharge - is a highly effective means of increasing corrosion crack resistance of high-strength alloys in the water medium. The effectiveness of inhibitors considered proves the hydrogen mechanism of water medium effect on crack growth in high-strength steels

36

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

37

Corrosion of stainless steels  

International Nuclear Information System (INIS)

The paper starts by describing the alloy components of stainless steels and then proceeds to discuss the corrosion processes. The chromium depletion theory, pitting, stress crack corrosion, intercrystalline corrosion, intercrystalline fatigue crack corrosion, corrosion due to deformation, and corrosion due to the formation of Evans' elements are discussed. Further sections deal with the brazing und welding of stainless steels and with the test solutions used. (orig./IHOE)

38

Polyindole top coat on TiO2 sol–gel films for corrosion protection of steel  

International Nuclear Information System (INIS)

Highlights: ? Polyindole top coating was electrochemically synthesized on TiO2 sol–gel coated stainless steel. ? The high protection was determined against corrosion; it was attributed to the adherent adsorption of the multilayer. ? Quantum calculations showed, there were a correlation experimental data and molecular parameters. - Abstract: The protection efficiency of polyindole film on stainless steel was enhanced via titanium dioxide pre-coating. The characterization of coatings was achieved by nuclear magnetic resonance and Fourier-transform infrared spectra. The surface morphology of electrodes was monitored with scanning electron microscope. The corrosion performance was investigated in 3.5% NaCl solution by electrochemical impedance spectroscopy and potentiodynamic measurements. The quantum calculations were employed, and theoretical parameters were determined. Results showed that the correlation between experimental and theoretical parameters. The high protection efficiency was observed against corrosion on the steel surface via forming a protective polyindole top coated titanium dioxide film.

39

Corrosion Protection of Stainless Steel by Polyaniline/Polypyrrole Composite Coating  

OpenAIRE

Electrochemical deposition of polyaniline/polypyrrole coatings on stainless steel was carried out by the constant potential technique. The surface properties and corrosion behavior of the coatings were studied by varying the time of deposition and the initial monomer concentration. The corrosion current and corrosion potential were measured by direct current polarization test. The changes in corrosion current and corrosion potential with the deposition timeand the initial monomer concentratio...

Subathira, A.; Rm, Meyyappan

2010-01-01

40

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

41

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

42

Influence of tantalum modifying addition on corrosion protective action of the diffusional chromized layers on carbon steel  

International Nuclear Information System (INIS)

The role of tantalum as of a modifying addition under 45 steel thermodiffusional saturation with chromium is investigated and a favourable effect of this element on the increase of protective properties of chromium-carbide coatings produced is demonstrated. A conclusion is made that the favourable effect of tantalum is conditioned by the production of carbide and other corrosion-resistant tantalum microphases in more deficient places of the coating in which an intense diffusional carbon supply from the protected steel is provided

43

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...

44

Corrosion Protection of Stainless Steel by Polyaniline/Polypyrrole Composite Coating  

Directory of Open Access Journals (Sweden)

Full Text Available Electrochemical deposition of polyaniline/polypyrrole coatings on stainless steel was carried out by the constant potential technique. The surface properties and corrosion behavior of the coatings were studied by varying the time of deposition and the initial monomer concentration. The corrosion current and corrosion potential were measured by direct current polarization test. The changes in corrosion current and corrosion potential with the deposition timeand the initial monomer concentration were thoroughly investigated. The surface energy of coated stainless steel was calculated by using dynamic contact angle analyzer.

A.Subathira

2010-12-01

45

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

46

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

47

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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

48

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...

49

The effect of oil on carbon dioxide corrosion inhibition on carbon steel - potential for improved corrosion protection  

International Nuclear Information System (INIS)

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 the experiments; two commercial inhibitor base chemicals; an oleic imidazoline salt (OI) and a phosphate ester (PE), and cetyl trimethyl ammonium bromide (CTAB), a well characterized quaternary ammonium compound. Adsorption characteristics of the inhibitors on corroding iron and FeCO3 particles were also studied. Polarization resistance (PR) and electrochemical impedance spectroscopy (EIS) techniques were used to study the effect of the oil on the performance of the inhibitors. The performance testing was done on corroding carbon steel without any surface deposits and on carbon steel with either ferrous carbonate (FeCO3) or ferric corrosion products on the surface. The results showed that the addition of oil in the inhibitor tests had a significant, positive effect on the performance of the two commercial corrosion inhibitors; decrease in corrosion rate of about one order of magnitude compared to the rate without oil was found. Based on the EIS data it was concluded thaBased on the EIS data it was concluded that the improved performance was caused by a modification of the inhibitor film and not the formation of a macroscopic oil film on the steel surface. Indications of oil wetting of the steel surface were only found when ferric corrosion products were present and OI was used as the inhibitor. No such effects were seen on bare steel or on FeCO3 covered surfaces. Contact angle measurements and dispersion tests were used to investigate the effect of the inhibitors on the wettability of the three types of surfaces when they were exposed to water and oil. Both the behavior of an oil droplet on an already water-wet surface and a water droplet on an already oil wet surface were investigated to determine the ability of the inhibitors to alter the affinity of the surface to water and oil respectively. The results indicated the no hydrophilic to hydrophobic transition occurred on bare steel and FeCO3 covered steel. The testing on surfaces with ferric corrosion products revealed that a water wet to oil-wet transition was possible on the ferric deposits using both PE and OI as inhibitor. The effect was, however, significantly stronger with OI than with PE. It was also found that the addition of the two inhibitors enhanced the hydrophobic behavior of an already oil-wet surface for both bare steel and steel with FeCO3 deposits. Water droplets entrained in the oil was in these experiments not able to spread on the steel surface. Electrophoresis measurements were used to determine influence of the three inhibitors on the zetapotential of FeCO3 and corroding iron particles. The tendency of the inhibitors to adsorb on surfaces with the same charge as the head group of the inhibitor was investigated. The focus in the testing on corroding iron was to determine the suitability of zetapotential as a method for investigating surface potential of corroding surfaces. It was found that the inhibitors adsorbed on iron carbonate regardless of the surface charge on the iron carbonate. On iron particles the experiments indicated that measurements of the surface potential of corroding particles could only be done when the corrosion rate had been reduced significantly using corrosion inhibitors. (Author)

50

Study on cerium-doped nano-TiO2 coatings for corrosion protection of 316?L stainless steel  

OpenAIRE

Many methods have been reported on improving the photogenerated cathodic protection of nano-TiO2 coatings for metals. In this work, nano-TiO2 coatings doped with cerium nitrate have been developed by sol–gel method for corrosion protection of 316?L stainless steel. Surface morphology, structure, and properties of the prepared coatings were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The corrosi...

Li, Suning; Wang, Qian; Chen, Tao; Zhou, Zhihua; Wang, Ying; Fu, Jiajun

2012-01-01

51

The corrosion protection of AISI(TM) 1010 steel by organic and inorganic zinc-rich primers  

Science.gov (United States)

The behavior of zinc-rich primer-coated AISI 1010 steel in 3.5-percent Na-Cl was investigated using electrochemical techniques. The alternating current (ac) method of electrochemical impedance spectroscopy (EIS), in the frequency range of 0.001 to 40,000 Hz, and the direct current (dc) method of polarization resistance (PR), were used to evaluate the characteristics of an organic, epoxy zinc-rich primer and an inorganic, ethyl silicate zinc-rich primer. A dc electromechanical galvanic corrosion test was also used to determine the corrosion current of each zinc-rich primer anode coupled to a 1010 steel cathode. Duration of the EIS/PR and galvanic testing was 21 days and 24 h, respectively. The galvanic test results demonstrated a very high current between the steel cathode and both zinc-rich primer anodes (38.8 and 135.2 microns A/sq cm for the organic and inorganic primers, respectively). The results of corrosion rate determinations demonstrated a much higher corrosion rate of the zinc in the inorganic primer than in the organic primer, due primarily to the higher porosity in the former. EIS equivalent circuit parameters confirmed this conclusion. Based on this investigation, the inorganic zinc-rich primer appears to provide superior galvanic protection and is recommended for additional study for application on solid rocket booster steel hardware.

Danford, M. D.; Mendrek, M. J.

1995-01-01

52

Corrosion protection mechanisms of carbon steel by an epoxy resin containing indole-3 butyric acid modified clay  

OpenAIRE

This work is an extension of studies into the mechanisms of corrosion protection of mild steel by an epoxy resin containing organically modified clay (Hang et al. [1]; Truc et al. [2]). In a previous study (Truc et al. [2]), it was shown that indole-3 butyric acid (IBA)-modified clay improved the corrosion performance of epoxy. In the present study, it was shown that the IBA is an anodic inhibitor and its efficiency was about 93%. Exfoliation and dispersion of the IBA-modified clay in the epo...

Hang, To Thi Xuan; Truc, Trinh Anh; Olivier, Marie-georges; Vandermiers, Catherine; Gue?rit, Nathalie; Pe?be?re, Nadine

2010-01-01

53

An electrochemical study of corrosion protection by primer-topcoat systems on 4130 steel with ac impedance and dc methods  

Science.gov (United States)

To investigate metal surface corrosion and the breakdown of metal protective coatings, the ac impedance method is applied to six systems of primer coated and primer topcoated 4130 steel. Two primers were used: a zinc-rich epoxy primer and a red lead oxide epoxy primer. The epoxy-polyamine topcoat was used in four of the systems. The EG and G-PARC Model 368 ac impedance measurement system, along with dc measurements with the same system using the polarization resistance method, were used to monitor changing properties of coated 4230 steel disks immersed in 3.5 percent NaCl solutions buffered at pH 5.4 over periods of 40 to 60 days. The corrosion system can be represented by an electronic analog called an equivalent circuit consisting of resistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for the resistors and capacitors, that can be assigned in the equivalent circuit following a least-squares analysis of the data, describe changes that occur on the corroding metal surface and in the protective coatings. Two equivalent circuits have been determined that predict the correct Bode phase and magnitude of the experimental sample at different immersion times. The dc corrosion current density data are related to equivalent circuit element parameters. Methods for determining corrosion rate with ac impedance parameters are verified by the dc method.

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

1988-01-01

54

Electrochemical synthesis of bilayer coatings of poly(N-methylaniline) and polypyrrole on mild steel and their corrosion protection performances  

International Nuclear Information System (INIS)

Highlights: ? The bilayers of poly(N-methylaniline) and polypyrrole-dodecylsulfate were synthesized. ? These films on mild steel were characterized by cyclic voltammetry, FTIR and FESEM. ? DS dopant allows permeation to cations and decreases the ingress of chloride ions. ? The PNMA/PPy-DS bilayer coating exhibited the best corrosion resistance in 0.5 M HCl. ? The protective properties of polymers was developed by preparing their bilayer coatings. - Abstract: Homopolymer and bilayer coatings of poly(N-methylaniline) (PNMA) and polypyrrole-dodecylsulfate (PPy-DS) have been electropolymerized on a mild steel (MS) surface by the potentiodynamic method in aqueous oxalic acid solutions. In order to include dodecylsulfate ion as dopant in the polypyrrole, sodium dodecylsulfate was also added to the polymerization solution of pyrrole. Characterization of coatings was carried out by the cyclic voltammetry, Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM). Corrosion behavior of the polymer coated MS electrodes was investigated in highly aggressive 0.5 M HCl solution by the Tafel test and electrochemical impedance spectroscopy (EIS) techniques. Corrosion test revealed that among the protective coatings obtained, the PNMA/PPy-DS bilayer exhibited the best corrosion resistance at all immersion times.

55

Electrochemical synthesis of bilayer coatings of poly(N-methylaniline) and polypyrrole on mild steel and their corrosion protection performances  

Energy Technology Data Exchange (ETDEWEB)

Highlights: > The bilayers of poly(N-methylaniline) and polypyrrole-dodecylsulfate were synthesized. > These films on mild steel were characterized by cyclic voltammetry, FTIR and FESEM. > DS dopant allows permeation to cations and decreases the ingress of chloride ions. > The PNMA/PPy-DS bilayer coating exhibited the best corrosion resistance in 0.5 M HCl. > The protective properties of polymers was developed by preparing their bilayer coatings. - Abstract: Homopolymer and bilayer coatings of poly(N-methylaniline) (PNMA) and polypyrrole-dodecylsulfate (PPy-DS) have been electropolymerized on a mild steel (MS) surface by the potentiodynamic method in aqueous oxalic acid solutions. In order to include dodecylsulfate ion as dopant in the polypyrrole, sodium dodecylsulfate was also added to the polymerization solution of pyrrole. Characterization of coatings was carried out by the cyclic voltammetry, Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM). Corrosion behavior of the polymer coated MS electrodes was investigated in highly aggressive 0.5 M HCl solution by the Tafel test and electrochemical impedance spectroscopy (EIS) techniques. Corrosion test revealed that among the protective coatings obtained, the PNMA/PPy-DS bilayer exhibited the best corrosion resistance at all immersion times.

Zeybek, Buelent [Ankara University, Faculty of Science, Department of Chemistry, Ankara (Turkey); Dumlupinar University, Faculty of Arts and Sciences, Department of Chemistry, Kuetahya (Turkey); Ozcicek Pekmez, Nuran, E-mail: npekmez@hacettepe.edu.t [Hacettepe University, Faculty of Science, Department of Chemistry, Ankara (Turkey); Kilic, Esma [Ankara University, Faculty of Science, Department of Chemistry, Ankara (Turkey)

2011-10-30

56

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)

57

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

Energy Technology Data Exchange (ETDEWEB)

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: {yields} Ordered mesoporous composite film was deposited on the 304 stainless steel. {yields} This composite film exhibited excellent protective performance in 0.5 M H{sub 2}SO{sub 4}. {yields} The film exhibited a high surface tension with water contact angle close to 90{sup o}. - 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, N{sub 2} adsorption-desorption and TEM, the composite films exhibit ordered mesoporous structures. The corrosion tests in 0.5 M H{sub 2}SO{sub 4} 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.

Wang Tao [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); He Jianping, E-mail: jianph@nuaa.edu.c [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Sun Dun; Zhou Jianhua; Guo Yunxia; Ding Xiaochun; Wu Shichao; Zhao Jianqing; Tang Jing [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2011-04-15

58

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.

59

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)

60

Surface treatment as corrosion protection measure of stainless steels. Oberflaechenbehandlung als Korrosionsschutzmassnahme von nichtrostenden Staehlen  

Energy Technology Data Exchange (ETDEWEB)

The pickling behaviour of several stainless austenitic steels and of one steel with ferritic/austenitic grain structure were investigated in pickling solutions of different compositions based on hydrofluoric acid. Because of uncertainties in practical applications, the influence of temperature, time and acid content on the mass loss is of high interest. In another series of experiments, aqueous solutions of citric acid were tested for their suitability as pickling chemicals for the materials X 6 CrNiTi 18 10 (AISI 321) and X 6 CrNiMoTi 17 12 2 (AISI 316 Ti). Finally, the pickling procedures based on nitric acid/hydrofluoric acid mixtures were compared with mechanical cleansing methods and with pickling procedures based on aqueous citric acid solutions as well, to elucidate their influence on the corrosion resistance of the treated materials. The valuation followed a pitting corrosion test in sodium chloride solutions of different concentrations after Herbsleb and Schwenk. Pickling with hydrofluoric acid solutions is superior to other cleansing procedures, if corrosive environments are present. The ecologically beneficial citric acid solutions are only able to remove the annealing colours from stainless steels. (orig.).

Reichau, U.; Pletka, H.D.; Schuetze, K.G. (DEGUSSA Deutsche Gold- und Silber-Scheideanstalt, Hanau (Germany))

1992-11-01

61

Composition and Morphology of Product Layers in the Steel/Cement Paste Interface in Conditions of Corrosion and Cathodic Protection in Reinforced Concrete :  

OpenAIRE

The present study explores the formation of corrosion products on the steel surface in reinforced concrete in conditions of corrosion and subsequent transformation of these layers in conditions of cathodic protection (CP). Of particular interest was to investigate if the introduced pulse CP (as cost- effective alternative of CP) will lead to similar (or even better) transformation of the product layers on the steel surface, compared to conventional techniques. Qualification and quantification...

Koleva, D. A.; Breugel, K.; Wit, J. H. W.; Fraaij, A. L. A.; Boshkov, N.

2007-01-01

62

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

Science.gov (United States)

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.; Gonzalez-Rodriguez, J. G.; Martinez, L.

1998-02-01

63

Steel protection from carbon dioxide corrosion with volatile inhibitors. II. Vapor phase  

International Nuclear Information System (INIS)

The peculiarities of protective effect of the primary amines: the octylamine, its highest homolog amine A and the new inhibitor IFKhAN-72 in the vapor-gas carbon acid medium are studied. It is shown, that the increase in the hydrophoby of the aliphatic amines and their directed modification (IFKhAN-72) increases its protection ability under the conditions of the periodic wetting. The new volatile inhibitor IFKhAN-72 may retain for a long time the corrosion aftereffect

64

Incorporation of Fe3O4/CNTs nanocomposite in an epoxy coating for corrosion protection of carbon steel  

Science.gov (United States)

In this study Fe3O4/CNTs composite with magnetic property was prepared by attaching magnetic nanoparticles (Fe3O4) to carbon nanotubes (CNTs) by hydrothermal method. The obtained Fe3O4/CNTs composite was characterized by Fourier transform infrared (FTIR) spectroscopy, powder x-ray diffraction and transmission electron microscopy. The Fe3O4/CNTs composite was then incorporated into an epoxy coating at concentration of 3 wt%. Corrosion protection of epoxy coating containing Fe3O4/CNTs composite was evaluated by electrochemical impedance spectroscopy and adhesion measurement. The impedance measurements show that Fe3O4/CNTs composite enhanced the corrosion protection of epoxy coating. The corrosion resistance of the carbon steel coated by epoxy coating containing Fe3O4/CNTs composite was significantly higher than that of carbon steel coated by clear epoxy coating and epoxy coating containing CNTs. FE-SEM photographs of fracture surface of coatings showed good dispersion of Fe3O4/CNTs composite in the epoxy matrix.

Pham, Gia Vu; Truc Trinh, Anh; To, Thi Xuan Hang; Duong Nguyen, Thuy; Trang Nguyen, Thu; Hoan Nguyen, Xuan

2014-09-01

65

Nanocomposite films for corrosion protection  

OpenAIRE

This thesis describes technical and scientific aspects of new types of composite films/coatings for corrosion protection of carbon steel, composite films with nanometer thickness consisting of mussel adhesive protein (Mefp?1) and ceria nanoparticles, and polymeric composite coatings with micrometre thickness consisting of conducting polymer and ceria nanoparticles in a UV?curing polyester acrylate (PEA) resin. The influence of microstructure on corrosion behaviour was studied for a Fe?C...

Sababi, Majid

2013-01-01

66

Study on cerium-doped nano-TiO2 coatings for corrosion protection of 316?L stainless steel.  

Science.gov (United States)

Many methods have been reported on improving the photogenerated cathodic protection of nano-TiO2 coatings for metals. In this work, nano-TiO2 coatings doped with cerium nitrate have been developed by sol-gel method for corrosion protection of 316?L stainless steel. Surface morphology, structure, and properties of the prepared coatings were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The corrosion protection performance of the prepared coatings was evaluated in 3?wt% NaCl solution by using electrochemical techniques in the presence and absence of simulated sunlight illumination. The results indicated that the 1.2% Ce-TiO2 coating with three layers exhibited an excellent photogenerated cathodic protection under illumination attributed to the higher separation efficiency of electron-hole pairs and higher photoelectric conversion efficiency. The results also showed that after doping with an appropriate concentration of cerium nitrate, the anti-corrosion performance of the TiO2 coating was improved even without irradiation due to the self-healing property of cerium ions. PMID:22515192

Li, Suning; Wang, Qian; Chen, Tao; Zhou, Zhihua; Wang, Ying; Fu, Jiajun

2012-01-01

67

Study on cerium-doped nano-TiO2 coatings for corrosion protection of 316 L stainless steel  

Science.gov (United States)

Many methods have been reported on improving the photogenerated cathodic protection of nano-TiO2 coatings for metals. In this work, nano-TiO2 coatings doped with cerium nitrate have been developed by sol-gel method for corrosion protection of 316 L stainless steel. Surface morphology, structure, and properties of the prepared coatings were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The corrosion protection performance of the prepared coatings was evaluated in 3 wt% NaCl solution by using electrochemical techniques in the presence and absence of simulated sunlight illumination. The results indicated that the 1.2% Ce-TiO2 coating with three layers exhibited an excellent photogenerated cathodic protection under illumination attributed to the higher separation efficiency of electron-hole pairs and higher photoelectric conversion efficiency. The results also showed that after doping with an appropriate concentration of cerium nitrate, the anti-corrosion performance of the TiO2 coating was improved even without irradiation due to the self-healing property of cerium ions.

Li, Suning; Wang, Qian; Chen, Tao; Zhou, Zhihua; Wang, Ying; Fu, Jiajun

2012-04-01

68

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

OpenAIRE

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 polys...

Jano, A.; Lame, A.; Kokalari, E.

2012-01-01

69

Galvanic Liquid Applied Coating System For Protection of Embedded Steel Surfaces from Corrosion  

Science.gov (United States)

Corrosion of reinforcing steel in concrete is an insidious problem facing Kennedy Space Center (KSC), other Government Agencies, and the general public. These problems include KSC launch support structures, highway bridge infrastructure, and building structures such as condominium balconies. Due to these problems, the development of a Galvanic Liquid Applied Coating System would be a breakthrough technology having great commercial value for the following industries: Transportation, Infrastructure, Marine Infrastructure, Civil Engineering, and the Construction Industry. This sacrificial coating system consists of a paint matrix that may include metallic components, conducting agents, and moisture attractors. Similar systems have been used in the past with varying degrees of success. These systems have no proven history of effectiveness over the long term. In addition, these types of systems have had limited success overcoming the initial resistance between the concrete/coating interface. The coating developed at KSC incorporates methods proven to overcome the barriers that previous systems could not achieve. Successful development and continued optimization of this breakthrough system would produce great interest in NASA/KSC for corrosion engineering technology and problem solutions. Commercial patents on this technology would enhance KSC's ability to attract industry partners for similar corrosion control applications.

Curran, Joseph; Curran, Jerome; Voska, N. (Technical Monitor)

2002-01-01

70

Failure mechanism of thin Al2O3 coatings grown by atomic layer deposition for corrosion protection of carbon steel  

International Nuclear Information System (INIS)

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) Al2O3 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 ?7 nm h-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.

71

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

Energy Technology Data Exchange (ETDEWEB)

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.

Weisenburger, A., E-mail: Alfons.weisenburger@kit.edu [KIT: Karlsruhe Instiute of Technology, Hermann-von-Helmholtz platz 1, 76344, Eggenstein-Leopoldshafen (Germany); Schroer, C.; Jianu, A.; Heinzel, A.; Konys, J.; Steiner, H.; Mueller, G.; Fazio, C. [KIT: Karlsruhe Instiute of Technology, Hermann-von-Helmholtz platz 1, 76344, Eggenstein-Leopoldshafen (Germany); Gessi, A. [ENEA: ENEA, CR Brasimone, 40032 Camugnano, Bologna (Italy); Babayan, S.; Kobzova, A. [NRI: Ustav jaderneho vyzkumu Rez a.s., Husinec 130, Rez 256068 (Czech Republic); Martinelli, L.; Ginestar, K.; Balbaud-Celerier, F. [CEA: CEA, DEN, Service de la Corrosion et du Comportement des Materiaux dans leur Environnement, F-91191 Gif sur Yvette (France); Martin-Munoz, F.J.; Soler Crespo, L. [CIEMAT: CIEMAT, Avda. Complutense, 22, 28040, Madrid (Spain)

2011-08-31

72

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

Directory of Open Access Journals (Sweden)

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

73

Atmospheric corrosion of mild steel  

OpenAIRE

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 c...

Morcillo, M.; La Fuente, D.; Di?az, I.; Cano, H.

2011-01-01

74

Corrosion study of carbon steel protected by a primer, by electrochemical impedance spectroscopy (EIS) in 3%NaCl medium and in a soil simulating solution  

Energy Technology Data Exchange (ETDEWEB)

The corrosion of underground structures, such as pipelines, depends on soil aggressiveness towards the metals. Two different methods of protection are used: (a) cathodic protection and (b) polymer coatings. The assessment of the degradation of buried structures is not easy because of the complex composition of the soil and its resistivity, and the risk of bacterial corrosion. Corrosion phenomena are generally studied in artificial solutions. The objective of the present paper is to study the protective capacity of coatings on pipeline steel using a ``primer`` paint exposed to conditions which are simulating the soil (soil simulating solution). The electrochemical behavior of uncoated and coated plates are estimated by means of electrochemical impedance spectroscopy (EIS) in two solutions: a reference media: 3% NaCl solution, and a ``soil simulating solution``. Appropriate models for impedance are used to fit the experimental data and extract the parameters which characterize the corrosion process. (orig.)

Belmokre, K. [Superior Normal School of Technical Teaching, Skikda (Algeria); Azzouz, N. [Superior Normal School, Jijel (Algeria); Kermiche, F. [U.S.T.H.B., Alger (Algeria). Electrochemical-Corrosion Lab.; Wery, M.; Pagetti, J. [Universite de Franche-Comte, Besancon (France). Corrosion Lab. and Surfaces Finishing

1998-02-01

75

An efficient protection of stainless steel against corrosion: Combination of a conversion layer and titanium dioxide deposit  

OpenAIRE

In the present work, a novel process has been developed to improve the corrosion properties of ferritic stainless steels. Titanium oxide coatings have been deposited onto stainless steel by sol–gel process after a pre-functionalization of the substrate in a conversion bath. Gel titania was prepared by hydrolysis of a titanium butoxide through a sol–gel process. Duplex systems “conversion layer/uniform TiO2 coating” have been prepared on stainless steels using a dipping tec...

Bamoulid, L.; Maurette, M. -t; Caro, D.; Guenbour, A.; Ben Bachir, A.; Aries, L.; El Hajjaji, S.; Benoit-marquie?, F.; Ansart, Florence

2008-01-01

76

Corrosion protection of type 304 stainless steel bipolar plates of proton-exchange membrane fuel cells by doped polyaniline coating  

Energy Technology Data Exchange (ETDEWEB)

Polyaniline coating doped with dodecylbenzesulfonate anions is electrodeposited galvanostatically on type 304 stainless steel used as bipolar plates of proton-exchange membrane fuel cell from a basic solution of 0.3 M aniline monomer solution containing sodium dodecylbenzesulfonate as a supporting electrolyte. Electrochemical measurements in 1 M H{sub 2}SO{sub 4} and in 0.3 M HCl show that the polyaniline coating increases the free corrosion potential of the steel by more than 300 mV and 450 mV, respectively, with a corrosion rate more than two orders of magnitude lower than that of the uncoated steel. Long-term exposure studies show that the coating is highly stable and inhibits the corrosion of the steel effectively. (author)

Ren, Y.J. [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016 (China); Department of Energy and Power Engineering, Changsha University of Science and Technology, Changsha 410076 (China); Chen, J. [Department of Energy and Power Engineering, Changsha University of Science and Technology, Changsha 410076 (China); Zeng, C.L. [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016 (China)

2010-04-02

77

Lubricant composition for protecting a rolling stock of carbon steel from corrosion and process for preparing it  

Energy Technology Data Exchange (ETDEWEB)

The lubricant composition being patented and consisting of a film former, inhibitor, and suitable solvent is for protecting a rolling stock of carbon steel from corrosion during its storage and transport. The inhibitor: film former weight ratio is 7-100:40-100, and the (film former + inhibitor):solvent weight ratio is 20:100 - 100:100. Zn naphthenates or ammonium or sodium salts of naphthenic acids appear as inhibitors. Plastic calcium greases with drop points of 85/sup 0/, industrial petrolatum with a drop point of 55/sup 0/, a residue from deparaffination (petrolatum), and mazut or petroleum oil with a pour point of -10/sup 0/ and a viscosity of 76-142 cSt/50/sup 0/ serve as the film formers; the solvents are white spirit or diesel fuel. For preparing the composition, the film former is melted, 75% of the total amount of solvent is added, the inhibitor is dissolved in the remaining 25% of the solvent, and both solutions are poured in and stirred until complete homogenization. The composition can be applied on a metal by brushing, spraying, or immersion. Example -- taken for preparing the composition is 14-55.8 g of a calcium plastic grease composition with a drop point of 85/sup 0/; it is melted and 1.4-13.5 g of Zn naphthenate and 50-100 mL of white spirit or diesel fuel are introduced. The lubricant assures protection from corrosion in the temperature range -20 to 50/sup 0/; for 1 m/sup 2/ of surface to be protected 0.1-0.15 kg of lubricant is required.

Bejan, F.I.; Balaban, L.; Focsaneanu, M.; Iliescu, E.; Radoviel, O.; Stancescu, M.; Streba, V.

1980-01-15

78

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...

79

Some peculiarities of corrosion of wheel steel  

Directory of Open Access Journals (Sweden)

Full Text Available 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 corrosion nucleation and their influence on corrosion depends on type of inclusion. Mechanism of corrosion of wheel steel corrosion was discussed.

Alexander SHRAMKO

2009-01-01

80

Layered double hydroxides as containers of inhibitors in organic coatings for corrosion protection of carbon steel  

OpenAIRE

The present work focuses on the use of layered double hydroxides (LDH) as containers for corrosion inhibitors in an epoxy coating. 2-Benzothiazolylthio-succinic acid (BTSA), used as corrosion inhibitor, was intercalated by co-precipitation in magnesium-aluminum layered double hydroxides. The obtained LDH-BTSA was characterized by infrared spectroscopy, X-ray diffraction and scanning electron microscopy. BTSA release from LDH-BTSA in NaCl solutions was investigated by UV-vis spectroscopy. The ...

Hang, To Thi Xuan; Truc, Trinh Anh; Duong, Nguyen Thuy; Pe?be?re, Nadine; Olivier, Marie-georges

2012-01-01

81

Evaluation of the protection behaviour of reinforcement steel against corrosion induced by chlorides in reinforced mortar specimens; Avaliacao do comportamento frente a corrosao pelo ataque de cloreto de argamassa armada apos varios tratamentos protetores  

Energy Technology Data Exchange (ETDEWEB)

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){sub 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)

Crivelaro, Marcos

2002-07-01

82

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

83

Multilayer Al{sub 2}O{sub 3}/TiO{sub 2} Atomic Layer Deposition coatings for the corrosion protection of stainless steel  

Energy Technology Data Exchange (ETDEWEB)

Atomic Layer Deposition (ALD) is used to deposit conformal nanometric layers onto different substrates. In this paper, characterization of different ALD layers has been carried out in order to evaluate the suitability of this deposition technolnique for the corrosion protection of stainless steel substrates. Al{sub 2}O{sub 3}, TiO{sub 2} and multilayer configurations, have been deposited on AISI 316 austenitic stainless steel and have then been investigated using atomic force microscopy (AFM), glow discharge optical emission spectrometry (GDOES), scanning electron microscopy (SEM), Vickers indentation and potentiodynamic polarizations (PP). AFM has been used to obtain a morphological characterization and to evaluate the thickness of the depositions. SEM has been used to investigate the presence of deposition defects. GDOES has been used to obtain a compositional profile. Vickers indentations were used in order to evaluate the resistance to delamination. PPs have been used in order to evaluate the corrosion protection. The results have showed that corrosion resistance can be effectively enhanced. Multilayer configuration proved to be more effective than single layers configurations. - Highlights: Black-Right-Pointing-Pointer Atomic Layer Deposition (ALD) coatings with different thicknesses were tested. Black-Right-Pointing-Pointer Glow Discharge Optical Emission Spectroscopy gave in-depth composition profiles. Black-Right-Pointing-Pointer Corrosion resistance was strongly enhanced by ALD. Black-Right-Pointing-Pointer Coating to substrate adhesion was improved for thin and multilayer coatings. Black-Right-Pointing-Pointer Multilayer ALD configurations proved to be more protective than single layers.

Marin, E., E-mail: elia.marin@uniud.it [University of Udine, 33100 Udine (Italy); Guzman, L.; Lanzutti, A. [University of Udine, 33100 Udine (Italy); Ensinger, W. [Darmstadt Technolnische Universitaet, 06151 Germany (Germany); Fedrizzi, L. [University of Udine, 33100 Udine (Italy)

2012-11-01

84

Corrosion protection of cold-rolled steel with alkyd paint coatings composited with submicron-structure types polypyrrole-modified nano-size alumina and carbon nanotubes  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Alumina/carbon nanotube (CNT) supported polypyrrole (PPy) particles were prepared. Black-Right-Pointing-Pointer Various paint compositions with alkyd binder were immersion tested. Black-Right-Pointing-Pointer Alumina-supported PPy based coating provided steel protection in NaCl solution. Black-Right-Pointing-Pointer Polyelectrolyte modified CNT embedded coating afforded long-term stable protection. Black-Right-Pointing-Pointer sulphonated CNT loaded coating indicated firm corrosion resistance in HCL solution. Black-Right-Pointing-Pointer Results are interpreted on the basis of nano and microstructure of the particles. - Abstract: This paper is focused on studying corrosion protection of cold-rolled steel with alkyd paint coatings comprising nano-size alumina and either polystyrene-sulphonate (PSS) modified or sulphonated multi-walled carbon nanotube (MWCNT) supported polypyrrole (PPy). Single layer coatings (in thickness of 40 {+-} 5 {mu}m) comprising PPy deposited alumina and PSS modified MWCNT supported PPy afforded viable protection during the 1 M sodium chloride test. The coatings containing PSS modified and weakly sulphonated MWCNTs (at volume fractions of 9.9 Multiplication-Sign 10{sup -4} and 2.5 Multiplication-Sign 10{sup -4}) with PPy volume fractions of 3.5 Multiplication-Sign 10{sup -3} and 2.5 Multiplication-Sign 10{sup -3} provided effective corrosion prevention during the 1 M sodium chloride and hydrochloric acid solution tests. While inhibitor particles were characterised by infrared spectroscopy, corrosion products formed at the paint-steel interface were studied by X-ray photoelectron spectroscopy. Apart from the electron microscopy observations, rheology study of three-dimensional structure of the inhibitor particles was performed in dispersions at similar compositions to those used for the paint formulations. Thus, protection mechanism relating to both types of immersion tests is discussed in terms of properties of the inhibitor particles and their microstructure in the coatings.

Gergely, Andras, E-mail: andras.gergely@ttk.mta.hu [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri ut 59-67, 1025 Budapest (Hungary); Paszti, Zoltan; Hakkel, Orsolya; Drotar, Eszter [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri ut 59-67, 1025 Budapest (Hungary); Mihaly, Judith [Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri ut 59-67, 1025 Budapest (Hungary); Kalman, Erika [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri ut 59-67, 1025 Budapest (Hungary)

2012-11-01

85

Corrosion protection of cold-rolled steel with alkyd paint coatings composited with submicron-structure types polypyrrole-modified nano-size alumina and carbon nanotubes  

International Nuclear Information System (INIS)

Highlights: ? Alumina/carbon nanotube (CNT) supported polypyrrole (PPy) particles were prepared. ? Various paint compositions with alkyd binder were immersion tested. ? Alumina-supported PPy based coating provided steel protection in NaCl solution. ? Polyelectrolyte modified CNT embedded coating afforded long-term stable protection. ? sulphonated CNT loaded coating indicated firm corrosion resistance in HCL solution. ? Results are interpreted on the basis of nano and microstructure of the particles. - Abstract: This paper is focused on studying corrosion protection of cold-rolled steel with alkyd paint coatings comprising nano-size alumina and either polystyrene-sulphonate (PSS) modified or sulphonated multi-walled carbon nanotube (MWCNT) supported polypyrrole (PPy). Single layer coatings (in thickness of 40 ± 5 ?m) comprising PPy deposited alumina and PSS modified MWCNT supported PPy afforded viable protection during the 1 M sodium chloride test. The coatings containing PSS modified and weakly sulphonated MWCNTs (at volume fractions of 9.9 × 10?4 and 2.5 × 10?4) with PPy volume fractions of 3.5 × 10?3 and 2.5 × 10?3 provided effective corrosion prevention during the 1 M sodium chloride and hydrochloric acid solution tests. While inhibitor particles were characterised by infrared spectroscopy, corrosion products formed at the paint–steel interface were studied by X-ray photoelectron spectroscopy. spectroscopy. Apart from the electron microscopy observations, rheology study of three-dimensional structure of the inhibitor particles was performed in dispersions at similar compositions to those used for the paint formulations. Thus, protection mechanism relating to both types of immersion tests is discussed in terms of properties of the inhibitor particles and their microstructure in the coatings.

86

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

87

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

88

Corrosion protection of steel in sulfuric acid using urotropin and additions with other inhibitors  

International Nuclear Information System (INIS)

It has been established that composite additives of inhibitors (I-1-A, I-1-B, BPV, and others) with urotropin + HCl are highly efficient in inhibiting sulfuric acid attack and hydrogenation of steel, their efficiency being highest at elevated temperatures (60, 90 deg C)

89

Protection of Mild Steel Against Sulphides Corrosion In Petroleum Oil Industry  

International Nuclear Information System (INIS)

The aggressive properties of the media encountered when drilling for oil derive from the fact that they contain an abundance of mineralized water, as well as hydrogen sulphide and carbon dioxide. Particularly vulnerable to corrosion and installation of old deposits, where highly mineralized water or sometimes even sea water, is pumped into the bed so as to increase the oil yield, and where acid treatment is also carried out, the injection of such water into the bed creates favourable conditions for the development of microbiological processes promoting the life activity of sulphate-reducing bacteria and contributing to the appearance of hydrogen sulphide in the system

90

Inhibitor protection of steel from corrosion and hydrogen impregnation, and the technology of chemical cleaning of equipment in solutions of sulfuric and sulfamic acids  

Energy Technology Data Exchange (ETDEWEB)

An analysis is made and the results are presented of investigations of the features of inhibitor protection of steel from corrosion and hydrogen impregnation and also of cleaning of industrial equipment in solutions of sulfuric and sulfamic acids. Acid cleaning of equipment (thermal power, chemical, petroleum refining, and petro-chemical industries, etc.) with hydrochloric acid is the most widely used. The data of plant investigations indicate the high protective effectiveness of inhibited sulfamic acid solutions; the best is an acid solution with additions of KhOSP-10 inhibitor. The sulfamic acid without inhibitor additions does not fulfill the requirements imposed for removal of scale and prevention of copper deposits.

Mindyuk, A.K.; Kost, Y.S.; Savitskaya, O.P.; Sholok, V.I.; Tkach, A.D.

1986-01-01

91

Protection of steel from corrosion and hydrogen absorption by organic inhibitors: experimental and quantum-chemical studies  

OpenAIRE

The step-strip anodic dissolution technique was used to obtain concentration profiles of cathodic evolved H2 across the depth of Cr-Ni1810 steel under corrosion in water-salt media in the presence of SRB. The proposed approximation of the experimentally obtained distribution of hydrogen along the depth of steel by means of standard Gaussian function made it possible to establish the integral hydrogen content of the sub-layer (up to 80 ?m) with high degree of accuracy. The efficiency of prote...

Beloglazov G.; Beloglazov S.

2013-01-01

92

Effect of gamma radiation on steel corrosion  

International Nuclear Information System (INIS)

An important materials issue of nuclear reactors concerns the chemical effects of ionizing radiation on steel corrosion. The effect of radiation on the corrosion kinetics of carbon steel and stainless steel was studied by electrochemical and chemical speciation analyses. The changes in the steel corrosion behaviour during the exposure to gamma radiation were followed by corrosion potential, linear polarization, and electrochemical impedance measurements. The corrosion kinetic measurements were also performed with steel exposed to H2O2 and O2 under non-irradiation conditions, and found the response of the corroding steel to gamma radiation could be mimicked with chemical addition of H2O2. (author)

93

Electrochemical and analytical study of some organic inhibitors used for carbon steel corrosion protection in water cooling systems  

International Nuclear Information System (INIS)

Water is the main cooling fluid in most industrial applications due to its wide existence in nature and its high specific heat capacity and its thermal conductivity. If pure water was used in cooling systems no problems will occur. However, due to the presence of suspended matter and dissolved solids and gases in water three main problems are encountered in industrial cooling systems; corrosion, scale, and growth of microorganisms which all badly affect the heat transfer efficiency of such system. This study is concerned with utilizing organic inhibitors to control corrosion of mild steel. Three inhibitors were used; 1-hydroxyethylene-1,1- diphosphonic acid (HEDP) as an example of phosphonates, sodium octanoate (C7H15-COONa)as an examples of carboxylates, and 2- phosphono-butane -1,2,4-tricarboxylic acid (PBTC) as an example of a compound having two effective groups: carboxylate and phosphonate (PBTC). City water available at site was used in the present study as a large number of cooling systems utilize water available at site together with mechanical and chemical treatment methods to control corrosion among the two other problems. Two experimental techniques were utilized, potentiodynamic polarization technique and gravimetric technique. The gravimetric technique included a flow loop to simulate the flowing condition of a cooling circuit and a one-day immersion test. Carbon steel specimens, polished to 120 and 600 grit size were used to investi120 and 600 grit size were used to investigate the effect of surface roughness on the corrosion inhibition efficiency.

94

Steel corrosion in radioactive waste storage tanks  

International Nuclear Information System (INIS)

A collaborative study is being conducted by CNEA and USDOE (Department of Energy of the United States of America) to investigate the effects of tank waste chemistry on radioactive waste storage tank corrosion. Radioactive waste is stored in underground storage tanks that contain a combination of salts, consisting primarily of sodium nitrate, sodium nitrite and sodium hydroxide. The USDOE, Office of River Protection at the Hanford Site, has identified a need to conduct a laboratory study to better understand the effects of radioactive waste chemistry on the corrosion of waste storage tanks at the Hanford Site. The USDOE science need (RL-WT079-S Double-Shell Tanks Corrosion Chemistry) called for a multi year effort to identify waste chemistries and temperatures within the double-shell tank (DST) operating limits for corrosion control and operating temperature range that may not provide the expected corrosion protection and to evaluate future operations for the conditions outside the existing corrosion database. Assessment of corrosion damage using simulated (non-radioactive) waste is being made of the double-shell tank wall carbon steel alloy. Evaluation of the influence of exposure time, and electrolyte composition and/or concentration is being also conducted. (author)

95

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

96

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

97

Corrosion inhibition performance of 2-mercaptobenzimidazole and 2-mercaptobenzoxazole compounds for protection of mild steel in hydrochloric acid solution  

Energy Technology Data Exchange (ETDEWEB)

The effect of some mercapto functional azole compounds on the corrosion of mild steel in 1 M hydrochloric acid solution was studied by polarization and electrochemical impedance spectroscopy (EIS). Polarization studies showed depression of cathodic and anodic polarization curves in the presence of mercapto functional azole compounds, indicating mixed type corrosion inhibition of the compounds. Double layer capacitance and charge transfer resistance values were derived from EIS results. Changes in impedance parameters are indicative of adsorption of these compounds on the metal surface. Surface analysis SEM/EDX showing presence of sulfur on the surface confirmed the adsorption of the azole compounds on the mild steel surface as showed by electrochemical methods. Both compounds contain a pyridine-like nitrogen atom and a sulfur atom in their molecular structure, while they differ in only one heteroatom: oxygen in the oxazole ring and pyrrole-like nitrogen in the imidazole ring. The results of the electrochemical techniques revealed that changing the pyrrole like nitrogen atom to oxygen atom in the azole ring results in a decrease of corrosion inhibition performance in hydrochloric acid solution, which could be related to more negative charge on pyrrole-like nitrogen atom in comparison to oxygen atom as depicted by quantum chemical calculations.

Mahdavian, M., E-mail: mahdavian@aut.ac.i [Department of Surface Coatings and Corrosion, Institute for Color Science and Technology, P.O. Box 16765-654, Tehran (Iran, Islamic Republic of); Ashhari, S. [Department of Surface Coatings and Corrosion, Institute for Color Science and Technology, P.O. Box 16765-654, Tehran (Iran, Islamic Republic of)

2010-02-01

98

Corrosion inhibition performance of 2-mercaptobenzimidazole and 2-mercaptobenzoxazole compounds for protection of mild steel in hydrochloric acid solution  

International Nuclear Information System (INIS)

The effect of some mercapto functional azole compounds on the corrosion of mild steel in 1 M hydrochloric acid solution was studied by polarization and electrochemical impedance spectroscopy (EIS). Polarization studies showed depression of cathodic and anodic polarization curves in the presence of mercapto functional azole compounds, indicating mixed type corrosion inhibition of the compounds. Double layer capacitance and charge transfer resistance values were derived from EIS results. Changes in impedance parameters are indicative of adsorption of these compounds on the metal surface. Surface analysis SEM/EDX showing presence of sulfur on the surface confirmed the adsorption of the azole compounds on the mild steel surface as showed by electrochemical methods. Both compounds contain a pyridine-like nitrogen atom and a sulfur atom in their molecular structure, while they differ in only one heteroatom: oxygen in the oxazole ring and pyrrole-like nitrogen in the imidazole ring. The results of the electrochemical techniques revealed that changing the pyrrole like nitrogen atom to oxygen atom in the azole ring results in a decrease of corrosion inhibition performance in hydrochloric acid solution, which could be related to more negative charge on pyrrole-like nitrogen atom in comparison to oxygen atom as depicted by quantum chemical calculations.

99

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

100

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

101

Corrosion of austenitic stainless steel  

International Nuclear Information System (INIS)

Types of corrosion observed in a heat exchanger pipe and on a support of still of molasses fermented wort, both in austenitic stainless steel, are focused. Not only are the causes which might have had any kind of influence on them examined, but also the measures adopted in order to avoid and lessen its occurence

102

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)

103

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

2014-09-01

104

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

105

Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel  

DEFF Research Database (Denmark)

Abstract Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria, e.g. on pipelines buried in soil and on marine structures. MIC of carbon steel must be monitored on-line in order to provide an efficient protection and control the corrosion. A number of monitoring techniques is industrially used today, and the applicability and reliability of these for monitoring MIC is evaluated. Coupons and ER are recommended as necessary basic techniques even though localised corrosion rate cannot be measured. FSM measures general corrosion and detects localised corrosion, but the sensitivity is not high enough for monitoring initiation of pitting and small attacks. Electrochemical techniques as LPR and EIS give distorted data and unreliable corrosion rates, when biofilm and corrosion products cover the steel surface. However, EIS might be used for detection ofMIC. EN is a suitable technique to characterise the type of corrosion attack, but is unsuitable for corrosion rate estimation. The concentric electrodes galvanic probe arrangement initiates localised corrosion on the anode and seems applicable to evaluate the risk of MIC. Hydrogen permeation measurements are very useful to monitor hydrogen induced cracking accelerated by MIC.

Hilbert, Lisbeth Rischel

2000-01-01

106

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

107

Synthesis and Application of Hybrid Polymer Composites Based on Silver Nanoparticles as Corrosion Protection for Line Pipe Steel  

Directory of Open Access Journals (Sweden)

Full Text Available 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.

Ayman M. Atta

2014-05-01

108

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

109

Corrosion behavior of 2205 duplex stainless steel.  

Science.gov (United States)

The corrosion of 2205 duplex stainless steel was compared with that of AISI type 316L stainless steel. The 2205 stainless steel is a potential orthodontic bracket material with low nickel content (4 to 6 wt%), whereas the 316L stainless steel (nickel content: 10 to 14 wt%) is a currently used bracket material. Both stainless steels were subjected to electrochemical and immersion (crevice) corrosion tests in 37 degrees C, 0.9 wt% sodium chloride solution. Electrochemical testing indicates that 2205 has a longer passivation range than 316L. The corrosion rate of 2205 was 0.416 MPY (milli-inch per year), whereas 316L exhibited 0.647 MPY. When 2205 was coupled to 316L with equal surface area ratio, the corrosion rate of 2205 reduced to 0.260 MPY, indicating that 316L stainless steel behaved like a sacrificial anode. When 316L is coupled with NiTi, TMA, or stainless steel arch wire and was subjected to the immersion corrosion test, it was found that 316L suffered from crevice corrosion. On the other hand, 2205 stainless steel did not show any localized crevice corrosion, although the surface of 2205 was covered with corrosion products, formed when coupled to NiTi and stainless steel wires. This study indicates that considering corrosion resistance, 2205 duplex stainless steel is an improved alternative to 316L for orthodontic bracket fabrication when used in conjunction with titanium, its alloys, or stainless steel arch wires. PMID:9228844

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

1997-07-01

110

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

111

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

112

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

113

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

114

Application of insulated protective coatings for reduction of corrosion potential of type 304 stainless steel in high-temperature water  

International Nuclear Information System (INIS)

An approach was developed for achieving a low electrochemical corrosion potential (ECP) on structural materials exposed to high-temperature water, even without the addition or presence of reducing species such as hydrogen (H2). This approach uses highly insulating coatings (e.g., yttria-stabilized zirconia [YSZ]) on structural materials to restrict the oxygen (O2) transport rate to the metal surface while simultaneously preventing formation of a differential aeration crevice cell because of its highly insulating character. Initial experimental data on type 304 stainless steel (SS[UNS 30400]) coated by air plasma spray showed ECP of YSZ-coated type 304 SS remained at ? -0.5 VSHE in 288 C water containing up to 200 ppb O2 and no H2

115

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

116

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

117

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)

118

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

119

Borosilicate glass corrosion in the presence of steel corrosion products  

International Nuclear Information System (INIS)

Since 1982, the corrosion behavior of radioactive high level waste glass and of inactive glasses of the same composition has been studied in the framework of a Japanese-Swedish-Swiss (JSS) project. In addition to granite and backfilling material, the influence of steel corrosion products on glass corrosion has been investigated in experiments of up to one year at 900C with a sample surface area to leachant volume ratio of 10 m-1. Leachant and steel corrosion products were separated from each other by filtration and analyzed by atomic absorption spectroscopy and ?-spectroscopy. The glass corrosion layers were characterized by optical and scanning electron microscopy and by secondary ion mass spectrometry. It could be shown, that glass corrosion is enhanced by steel corrosion products. The quantity of corroded glass seems to be dependent on the surface area and not on the total amount of steel corrosion products in the system, suggesting a mechanism controlled by silica sorption on the steel corrosion product. If lead oxide is added to the system, glass corrosion is almost totally suppressed. 9 references, 11 figures, 4 tables

120

Novel Corrosion Inhibitor for Mild Steel in HCl  

Directory of Open Access Journals (Sweden)

Full Text Available Corrosion inhibitory effects of new synthesized compound namely 5,5'- ((1Z,1'Z-(1,4-phenylenebis(methanylylidenebis(azanylylidenebis(1,3,4-thiadiazole-2-thiol (PBB on mild steel in 1.0 M HCl was investigated at different temperatures using open circuit potential (OCP, potentiodynamic polarization (PDP and electrochemical impedance spectroscopy (EIS. Results showed that PBB inhibited mild steel corrosion in acid solution and indicated that the inhibition efficiencies increased with the concentration of inhibitor, but decreased proportionally with temperature. Changes in impedance parameters suggested the adsorption of PBB on the mild steel surface, leading to the formation of protective films.

Ahmed A. Al-Amiery

2014-01-01

121

Corrosion inhibition of steel in lithium bromide brines  

International Nuclear Information System (INIS)

The inhibition effect of the molybdophosphoric acid (MPA) on the low-carbon steel St.3 in the 65% LiBr solution within the wide range of pH and temperatures as well as the possibility of increasing its efficiency through the additions of another in organic corrosion inhibitor are studied. It is shown, that the molybdo-phosphoric acid in the acid brines is an effective steel corrosion inhibitor only at the temperature above 120 Deg C. It is possible also to extent the temperature range of the effective steel protection by means of combined introduction of the inorganic inhibitor ICF into the MPA brines

122

Microbial corrosion inhibition of mild steel in salty water environment  

International Nuclear Information System (INIS)

The use of antimicrobial corrosion inhibitor is increasingly being curtailed by recent corrosion restrictions. This paper represents the results of the study of new biocide, antimicrobial corrosion inhibitor named 8-hydroxy-N'-(2-(quinolin-8-yloxy)acetyl)quinoline-5-sulfonohydrazide (HQS) was used to inhibit corrosion causing sulphate reducing bacteria (SRB). The effects of the inhibitor on mild steel dissolution in salty water environment were studied through weight loss measurements, electrochemical and microorganism tests. The results obtained from this study show that, the new inhibitor can decrease corrosion and microbial growth under the conditions tested. The mass loss for the protected mild steel coupons shows lower corrosion rate compared to the unprotected once. Cyclic polarization test reveals that, the biocide minimizes the pitting area (hysteresis). The nature of protective film formed on mild steel was studied by scanning electron microscopy (SEM). SEM images revealed that, the corrosion inhibition by the HQS on the mild steel surface significantly improved in the presence of biocide

123

Influence of corrosion on the light steel gauge framing  

Directory of Open Access Journals (Sweden)

Full Text Available Construction technology based on the light steel gauge construction is a frame technology, allowing erecting houses in a short time. The essence of this technology is using panels of light steel galvanized perforated and non-perforated profile, which form the metal frame of the building. There are many characteristics of LSGF that have been explored for nowadays. One of the main such characteristics is corrosion resistance. Corrosion protection of light steel structures are extremely important. For the construction of steel structures, electrochemical corrosion has the main importance. Electrochemical corrosion processes take place in aqueous solutions. When the metal surface in contact with the electrolyte solution there is an interaction of the metal with charged particles of solution and the transition metal ions into the solution. It is known that stress corrosion cracking occurs under the action of tensile stresses, which cause dilation of cracks. Compressive stresses counteract cracking, causing the closure of cracks. Growth of carbon content in steel leads to growth of its resistance to stress corrosion including in environments of nitrides and hydroxides. Reducing the grain size of steel increases its resistance to cracking, which is associated with the increase of cracking of path and strength increase. In a high risk of corrosion, it is better to use solid, closed sections than lattice. Greater consumption of steel will pay off as a result of increasing physical strength of the structure. Currently, the most common method of corrosion protection is the application of coatings in a layer of paint. They concede superiority in terms of stability, plated and metal coatings, but more are available.

Maria Vladimirovna Ananina

2014-07-01

124

Present and future corrosion protection concepts for surface-treated fine steel sheet products; Heutige und zukuenftige Korrosionsschutzkonzepte bei Einsatz oberflaechenveredelter Feinblechprodukte  

Energy Technology Data Exchange (ETDEWEB)

Many important functions of components are defined by their surface characteristics. For this reason, unalloyed or low-alloyed steels used in an aggressive atmosphere must be surface-treated for corrosion protection. Coating methods have reached an advanced technical status, and steel producers are ever attempting to develop and apply new processes for continuous steel band coating. One of the new options is a process which combines vapour deposition with novel purification techniques or with conventional surface treatment technologies. [German] Wichtige Funktionen vieler Bauteile werden von den Eigenschaften ihrer Obeflaechen bestimmt. Daher ist bei Verwendung unlegierter oder niedrig legierter Stahlsorten in agressiver Atmosphaere eine Oberflaechenveredelung als Korrosionsschutz erforderlich. Die herkoemmlichen Bandveredelungsverfahren der Elektrolytischen Metallabscheidung, der Schmelztauchveredelung und der Organischen Bandbeschichtung haben einen hohen Entwicklungsstand erreicht. Dies gilt sowohl fuer die Produktivitaet als auch die Qualitaet. Unsere Bemuehungen als Stahlhersteller gehen dahin, diesen Stand zu halten und darueberhinaus in kreativer Partnerschaft mit den Kunden die Entwicklung und Anwendung innovativer Beschichtungstechnologien fuer die kontinuierliche Stahlbandveredelung voranzutreiben. Eine Moeglichkeit dazu ist das Verfahren der Bandbedampfung in Kombination mit neuartigen Reinigungstechnologien, aber auch mit konventionellen Oberflaechenveredelungstechnologien. (orig.)

Warnecke, W.; Wolfhard, D. [Thyssen Krupp Stahl AG, Dortmund (Germany)

1999-07-01

125

Low-temperature atomic layer deposition of Al2O3 thin coatings for corrosion protection of steel: Surface and electrochemical analysis  

International Nuclear Information System (INIS)

Highlights: ? 10-100 nm Alumina coatings grown by ALD at 160 oC for protection of steel. ? Al2O3 stoichiometry of the coating and trace contamination by growth precursors. ? Iron oxide and siloxane presence at the buried coating/steel interface. ? Exponential decay of coating porosity over four orders of magnitude with thickness increase. ? Coating thickness increase required to seal the defective first deposited 10 nm. - Abstract: ToF-SIMS, XPS, voltammetry and EIS investigation of the anti-corrosion properties of thin (10, 50 and 100 nm) alumina coatings grown by atomic layer deposition at 160 oC on steel is reported. Surface analysis shows a thickness-independent Al2O3 stoichiometry of the coating and trace contamination by the growth precursors. The buried coating/alloy interface has iron oxide formed in ambient air and/or resulting from the growth of spurious traces in the initial stages of deposition. Electrochemical analysis yields an exponential decay of the coating porosity over four orders of magnitude with increasing thickness, achieved by sealing of the more defective first deposited 10 nm.

126

Corrosion of plasma nitrided austenitic stainless steels  

International Nuclear Information System (INIS)

The corrosion behaviour of plasma nitrided austenitic stainless steel grades AISI 304, 316 and 321 was studied at various temperatures. Certain plasma nitriding cycles included a post-oxidation treatment. The corrosion rates were measured using linear polarisation technique. Results showed that corrosion rate increased with the plasma nitriding temperature. Minimum deterioration occurred at 653K. (author). 2 tabs., 4 figs., 10 refs

127

Corrosion of Electrogalvanized Steel in 0.1 M NaCl Studied by SVET  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in english 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.

128

Corrosion of Electrogalvanized Steel in 0.1 M NaCl Studied by SVET  

Directory of Open Access Journals (Sweden)

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

2003-01-01

129

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

130

KhOD-1 - highly efficient inhibitor of corrosion and corrosion-fatigue fracture in steel  

Energy Technology Data Exchange (ETDEWEB)

Investigation results on protective ability of KhOD-1 inhibitor, which does not form foam in acid solutions, as well as of KhOSP-10, KI-1, PB-5, BA-6 inhibitors and urotropin (in concentration of 1 g/l) during deceleration of corrosion and corrosion-mechanical fracture of steels 40Kh and 20 in solutions of sulphuric, hydrochloric and phosphoric acids, have been presented. Corrosion rate is determined by weight method, and characteristics of corrosion-mechanical fracture during corrosion cracking and low-cycle fatigue. It is established that KhOD-1 inhibitor ensures high protection in solutions of sulphuric, phosphoric and hydrochloric acids, at that, it realizes its protective properties to the utmost in 5 N HCl, especially after its preliminary heating to 90 deg C for 30 min. Urotropin additions are the weakest ones as to their protective effect.

Mindyuk, A.K.; Savitskaya, O.P.; Tkach, A.D.; Kost' , Yu.S. (AN Ukrainskoj SSR, Lvov. Fiziko-Mekhanicheskij Inst.)

131

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

132

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

OpenAIRE

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 f...

Pepenar, Ioan

2013-01-01

133

Characteristics of Corrosion Product Layer Formed on Weathering Steel Exposed to the Tropical Climate of Vietnam  

OpenAIRE

The weathering steel (Corten B) was exposed to out-door atmosphere of Hanoi (urban site) and Donghoi (marine site). The results showed the protective ability of corrosion product layer formed on weathering steel in the initial stage. The SEM-EDX analysis detected the presence of chromium and copper in the inner layers of corrosion product formed on weathering steel. These elements improved corrosion resistance of corr...

Le Thi Hong Lien; Hoang Lam Hong

2013-01-01

134

General corrosion of carbon steels in high temperature water  

International Nuclear Information System (INIS)

This short paper seeks to provide a summary of the main knowledge about the general corrosion of carbon steels in high temperature water. In pure water or slightly alkaline deaerated water, steels develop a protective coating of magnetite in a double layer (Potter and Mann oxide) or a single layer (Bloom oxide). The morphology of the oxide layer and the kinetics of corrosion depend on the test parameters controlling the solubility of iron. The parameters exercising the greatest influence are partial hydrogen pressure and mass transfer: hydrogen favours the solubilization of the magnetite; the entrainment of the dissolved iron prevents a redeposition of magnetite on the surface of the steel. Cubic or parabolic in static conditions, the kinetics of corrosion tends to be linear in dynamic conditions. In dynamic operation, corrosion is at least one order of magnitude lower in water with a pH of 10 than in pure water with a pH of 7. The activation energy of corrosion is 130 kJ/mol (31 kcal/mol). This results in the doubling of corrosion at around 300 deg C for a temperature increase of 15 deg C. Present in small quantities (100-200 ppb), oxygen decreases general corrosion but increases the risk of pitting corrosion - even for a low chloride content - and stress corrosion cracking or corrosion-fatigue. The steel composition has probably an influence on the kinetics of corrosion in dynamic conditions; further work would be required to clarify the effect of some residual elements. (author). 31 refs., 9 figs., 2 tabs

135

Corrosion protection of prestressing tendons  

International Nuclear Information System (INIS)

Laboratory experiments were carried out to determine the cause of pitting corrosion on greased prestressing tendons. It was found that pitting resulted from the combined action of the corrosion inhibitor in the grease and sea-salt contamination, and that both the initiation of pits and their subsequent growth were dependent on the relative humidity of the environment. The principles of corrosion protection established from this work required careful selection of the grease, and control of airborne contamination and relative humidity throughout the manufacture and installed life of the tendons. (author)

136

Role of climatic conditions on corrosion characteristics of structural steels  

International Nuclear Information System (INIS)

Corrosion behaviour of low alloy (LASS) and plain carbon (PCSS) structural steels exposed in different types of climatic conditions and nature of rust formed on their surfaces have been studied after 2 years of exposures. The test sites were chosen to represent four types of environments who strongly influence the corrosion of metals and alloys. They include (a) humid-saline, (b) humid-saline-urban (c) humid-industrial and (d) plain dry-urban environments. Mass loss, Raman spectroscopy, scanning electron microscopy and electrochemical impedance spectroscopic studies have been performed to study the corrosion behaviour and characterise the nature of rusts formed on these steels. Mass loss measurement technique has been used to determine the loss of thickness of steels during their atmospheric and salt spray exposures. Results indicate that the corrosion rate of steels is strongly influenced by the climatic conditions prevailing at the exposure sites. The presence of SO2 and salinity in the environments change the structure and protective properties of rust formed on the steels' surface. Electrochemical impedance and cyclic polarisation studies of the steels in simulated environments have been performed to understand the mechanism of corrosion in different climatic conditions

137

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

138

Scaling and corrosion damage of mild steel and low alloy steel in boiler feedwater  

International Nuclear Information System (INIS)

Initial corrosion of mild steel and low alloy steel in boiler feed water results in corrosion restraining oxide layers. Experiments on formation of these layers in flowing (up to 4 m/s) simulated feedwater (up to 180 deg C) are presented. According to the oxygen content of the water and depending on the hydrodynamic conditions in the tubes three different types of layers were observed. Mechanism of formation and the effect of formation are discussed. Chloride can be damaging to the corrosion restraining or protecting effects of the oxides. The different effects of chloride contaminations are discussed for the three types of layers. (author)

139

Development of novel protective high temperature coatings on heat exchanger steels and their corrosion resistance in simulated coal firing environment; Developpement de revetements pour les aciers d'echangeurs thermiques et amelioration de leur resistance a la corrosion en environnement simulant les fumees de combustion et de charbon  

Energy Technology Data Exchange (ETDEWEB)

Improving the efficiencies of thermal power plants requires an increase of the operating temperatures and thus of the corrosion resistance of heat exchanger materials. Therefore, the present study aimed at developing protective coatings using the pack cementation process. Two types of heat exchanger steels were investigated: a 17% Cr-13% Ni austenitic steel and three ferritic-martensitic steels with 9 (P91 and P92) and 12% Cr (HCM12A). The austenitic steel was successfully aluminized at 950 C. For the ferritic-martensitic steels, the pack cementation temperature was decreased down to 650 C, in order to maintain their initial microstructure. Two types of aluminides, made of Fe{sub 2}Al{sub 5} and FeAl, were developed. A mechanism of the coating formation at low temperature is proposed. Furthermore, combining the pack cementation with the conventional heat treatment of P91 allowed to take benefit of higher temperatures for the deposition of a two-step Cr+Al coating. The corrosion resistance of coated and uncoated steels is compared in simulated coal firing environment for durations up to 2000 h between 650 and 700 C. It is shown that the coatings offer a significant corrosion protection and, thus, an increase of the component lifetime. Finally, the performance of coated 9-12% Cr steels is no longer limited by corrosion but by interdiffusion between the coating and the substrate. (author)

Rohr, V.

2005-10-15

140

SYNERGIC MIXTURES PROTECTIVE ACTION AS THE FUNCTION OF WATER-SALINE MEDIUM COMPONENTS NATURE AND RATIO OF ITS CONCENTRATIONS AT CORROSION OF STEEL  

OpenAIRE

The relation between the ratio of concentrations of components in binary mixtures of adsorption and passivation effects inhibitors; its influence on the corrosion-electrochemical behavior in aqueous salt mediums (method of isomolar series) was studied. It was shown that this effect has an extremum character, where the most corrosion inhibition of anodic reaction is achieved at synergistic maximum where also achieved almost complete corrosion protection.

?????????, ????????? ???????????; ????????, ??????? ?????????????

2012-01-01

141

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

142

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

OpenAIRE

The corrosion behavior and thermal stability of epoxy coatings electrodeposited on mild steel and on mild steel with electrochemically deposited polyaniline (PANI) film were investigated by electrochemical impedance spectroscopy (EIS) and thermo gravimetric analysis (TGA). The aim of the paper was to present new findings on the corrosion protection of mild steel by a duplex PANI/-epoxy coating in 3% NaCI solution and to determine the effect of thin PANI film on the protective properties of th...

Gvozdenovi? Milica M.; Grgur Branimir N.; Ka?arevi?-Popovi? Zorica M.; Miškovi?-Stankovi? Vesna B.

2005-01-01

143

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

144

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)

145

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

146

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

147

Corrosion behaviour of solution nitrided stainless steels  

Energy Technology Data Exchange (ETDEWEB)

The case of near net shape parts made from austenitic steel X2CrNiMo17-13-2 and austenitic-ferritic steels X2CrNiMoN22-5-3 (wrought) and G-X3CrNiMoCuN26-6-3-3 (cast) is interstitially enriched with nitrogen by the diffusion-based process ''solution nitriding''. In order to obtain good corrosion resistance and mechanical properties, the solution nitriding parameters and the applied cooling time are selected so, that precipitates are avoided (X2CrNiMo17-13-2, X2CrNiMoN22-5-3). However, in case of a superimposed hydroabrasive load, the presence of nitrides in the case is found to be beneficial. The solution nitrided and the solution annealed conditions of the steels are compared with respect to their susceptibility to corrosion by means of electrochemical polarisation curves. The erosion corrosion behaviour of the materials is analysed in pilot scale flow-loop tests using particle loaded corrosive and particle loaded non-corrosive media. It is shown that ''solution nitriding'' leads to improved corrosion behaviour and/or improved erosion corrosion resistance, in particular in the case of the duplex steels. (orig.)

Berns, H.; Juse, R.L. [Bochum Univ. (Germany); Eul, U.; Heitz, E. [Deutsche Gesellschaft fuer Chemisches Apparatewesen, Chemische Technik und Biotechnologie e.V. (DECHEMA), Frankfurt am Main (Germany)

1999-07-01

148

Corrosion behaviour of solution nitrided stainless steels  

International Nuclear Information System (INIS)

The case of near net shape parts made from austenitic steel X2CrNiMo17-13-2 and austenitic-ferritic steels X2CrNiMoN22-5-3 (wrought) and G-X3CrNiMoCuN26-6-3-3 (cast) is interstitially enriched with nitrogen by the diffusion-based process ''solution nitriding''. In order to obtain good corrosion resistance and mechanical properties, the solution nitriding parameters and the applied cooling time are selected so, that precipitates are avoided (X2CrNiMo17-13-2, X2CrNiMoN22-5-3). However, in case of a superimposed hydroabrasive load, the presence of nitrides in the case is found to be beneficial. The solution nitrided and the solution annealed conditions of the steels are compared with respect to their susceptibility to corrosion by means of electrochemical polarisation curves. The erosion corrosion behaviour of the materials is analysed in pilot scale flow-loop tests using particle loaded corrosive and particle loaded non-corrosive media. It is shown that ''solution nitriding'' leads to improved corrosion behaviour and/or improved erosion corrosion resistance, in particular in the case of the duplex steels. (orig.)

149

Characteristics of Corrosion Product Layer Formed on Weathering Steel Exposed to the Tropical Climate of Vietnam  

Directory of Open Access Journals (Sweden)

Full Text Available The weathering steel (Corten B was exposed to out-door atmosphere of Hanoi (urban site and Donghoi (marine site. The results showed the protective ability of corrosion product layer formed on weathering steel in the initial stage. The SEM-EDX analysis detected the presence of chromium and copper in the inner layers of corrosion product formed on weathering steel. These elements improved corrosion resistance of corrosion product layers. In addition, the dense ?-FeOOH phase were appeared early in corrosion product which is detected by X-ray diffraction and Micro Raman investigations. The results of polarization and EIS measurements also demonstrated the protectiveness of the corrosion product of weathering steel.

Le Thi Hong Lien

2013-07-01

150

Corrosion of two oxide-covered steels  

Science.gov (United States)

Determining the corrosive response of pipeline steel under laboratory immersion conditions can be difficult when an adequate reproduction of feild conditions is required. The difficulty is multiplied when testing an oxide-covered surface. Corrosion standards do not adequately cover testing oxide-covered steels. Methodology is developed to test the corrosive response of oxide-covered steels, especially pre-immersion surface oxides such as millscale. The methodology focuses on open-circuit potential monitoring, polarization, mass loss and surface examination. Procedures are recommended for specimen preparation, equipment to handle hostile media, test sequencing, specimen cleaning, and preparation for post-immersion examination. Long standing belief's regarding the interaction of millscale in the corrosive response of a steel originating from pre-1950's steel immersed in sea water that have propagated are: the presence of millscale causes pitting and scatter in corrosive testing results or is negligible due to quick removal. Results from A36 and X70 steels in dearated high chloride ion containing environments indicate that an adjustment of historical industry perspectives of millscale is required. Millscale does not cause pitting. Pitting is material/environment dependent. A material/environment that is prone to pitting will, at least initially, experience a concentration of the corrosion at breaks in the millscale. The presence of millscale does not ensure pitting will occur. Scatter in the corrosion parameters determined from mass loss and polarizations are not related to the presence or absence of millscale but due to a combination of testing methodology and material/environment. Removal of millscale is material/environment dependent requiring very acidic conditions to negate the interaction in the materials corrosive response. The presence of millscale can be enhanced by oxide growth during immersion.

Schwarz-Tonhauser, Melissa

151

Corrosion models of carbon steel container  

International Nuclear Information System (INIS)

Carbon steel is one kind of the common package materials used for storage of low and intermediate level radioactive liquid waste or disposal of low and intermediate level radioactive solidified waste. The integrity of the package container is an important factor preventing radionuclide releasing from the container. The main mechanism of package container breakage is corrosion. And the concerned matters are pitting and uniform corrosions of package container under storage or disposal of the waste. The situation concerning this aspect and both pitting corrosion models and uniform corrosion models are introduced in this paper. (authors)

152

Atmospheric crevice corrosion of stainless steels  

Energy Technology Data Exchange (ETDEWEB)

Crevice corrosion of stainless steels such as high-strength 08X15H5{Pi}2T, 06X14H6{Pi}2M{Pi}T, 03X10H11M2T, 03X12H10MT, 03X9H9K5m3, 13X11H2B2M{Phi}, 20X13, 40X13, 95X18, and 12X18H10T steels has been studied in salt spray fog, using specially designed specimens. The steels were subdivided into three groups according to crevice corrosion resistance. A test solution containing NaCl and (NH{sub 4}){sub 2}S{sub 2}O{sub 8} has been elaborated for fast determination of susceptibility of stainless steels to crevice corrosion.

Belous, V.Ya.; Gurvich, L.Ya.; Erofeeva, V.L. [and others

1995-03-01

153

POLYETHERSULFONE COATING FOR MITIGATING CORROSION OF STEEL IN GEOTHERMAL ENVIRONMENT.  

Energy Technology Data Exchange (ETDEWEB)

Emphasis was directed toward evaluating the usefulness of a polyethersulfone (PES)-dissolved N-methyl pyrrolidone (NMP) solvent precursor as a low-temperature film-forming anti-corrosion coating for carbon steel in simulated geothermal environments at brine temperatures up to 300 C. A {approx} 75 {micro}m thick PES coating performed well in protecting the steel against corrosion in brine at 200 C. However, at {>=} 250 C, the PES underwent severe hydrothermal oxidation that caused the cleavage of sulfone- and ether-linkages, and the opening of phenyl rings. These, in turn, led to sulfone {yields} benzosulfonic acid and ether {yields} benzophenol-type oxidation derivative transformations, and the formation of carbonyl-attached open rings, thereby resulting in the incorporation of the functional groups, hydroxyl and carbonyl, into the coating. The presence of these functional groups raised concerns about the diminutions in water-shedding and water-repellent properties that are important properties of the anti-corrosion coatings; such changes were reflected in an enhancement of the magnitude of susceptibility of the coatings surfaces to moisture. Consequently, the disintegration of the PES structure by hydrothermal oxidation was detrimental to the maximum efficacy of the coating in protecting the steel against corrosion, allowing the corrosive electrolytes to infiltrate easily through it.

SUGAMA, T.

2005-06-01

154

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

155

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

156

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

157

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

158

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

159

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

160

Metallic corrosion of steels embedded in calcium aluminate cement mortars  

OpenAIRE

In the present paper, the corrosion levels of reinforcing steels embedded in Calcium Aluminate Cement (CAC) mortars have been studied. Experiments were designed to investigate the influence of the following factors in steel corrosion: cover thickness, type of steel (carbon steel (CS) and stainless steel (SS)), temperature at mixing and curing, influence of chloride concentration, nitrite ion as corrosion inhibitor and carbonation of mortar. The reinforcing steel bars do not become more corrod...

Garci?a Andio?n, Luis; Garce?s Terradillos, Pedro; Cases Iborra, Francisco Javier; Garci?a Andreu, Ce?sar; Va?zquez Pico?, Jose? Luis

2001-01-01

161

Development of novel protective high temperature coatings on heat exchanger steels and their corrosion resistance in simulated coal firing environment  

OpenAIRE

Afin d'augmenter leur rendement, les centrales thermiques sont amenées à élever leur température de fonctionnement. Ceci nécessite une amélioration de la résistance à la corrosion des matériaux constitutifs des échangeurs de chaleur. Ainsi, l'objet de cette étude est de développer des revêtements anticorrosion à partir du procédé de cémentation activée. Deux types d'aciers pour échangeurs de chaleur ont été étudiés : un acier austénitique contenant 17% Cr et 13% Ni, et...

Rohr, Valentin

2005-01-01

162

Space Shuttle Corrosion Protection Performance  

Science.gov (United States)

The reusable Manned Space Shuttle has been flying into Space and returning to earth for more than 25 years. The launch pad environment can be corrosive to metallic substrates and the Space Shuttles are exposed to this environment when preparing for launch. The Orbiter has been in service well past its design life of 10 years or 100 missions. As part of the aging vehicle assessment one question under evaluation is how the thermal protection system and aging protective coatings are performing to insure structural integrity. The assessment of this cost resources and time. The information is invaluable when minimizing risk to the safety of Astronauts and Vehicle. This paper will outline a strategic sampling plan and some operational improvements made by the Orbiter Structures team and Corrosion Control Review Board.

Curtis, Cris E.

2007-01-01

163

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.

164

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

International Nuclear Information System (INIS)

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

165

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

166

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

167

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

168

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

169

Corrosion of Steels in Steel Reinforced Concrete in Cassava Juice  

Science.gov (United States)

The corrosion of two types of construction steels, ST60Mn and RST37-2?, in a low cyanide concentration environment (cassava juice) and embedded in concrete had been studied. The ST60 Mn was found to be more corrosion resistant in both ordinary water and the cassava juice environment. The cyanide in cassava juice does not attack the steel but it provides an environment of lower pH around the steel in the concrete which leads to breakdown of the passivating film provided by hydroxyl ions from cement. Other factors such as the curing time of the concrete also affect the corrosion rates of the steel in the concrete. The corrosion rate of the steel directly exposed to cassava juice i.e., steel not embedded in concrete is about twice that in concrete. Long exposure of concrete structure to cassava processing effluent might result in deterioration of such structures. Careful attention should therefore be paid to disposal of cassava processing effluents, especially in a country like Nigeria where such processing is now on the increase.

Oluwadare, G. O.; Agbaje, O.

170

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

171

Metronidazole: A Corrosion Inhibitor for Mild Steel in Aqueous Environment  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in english 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

172

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

173

Corrosion inhibition of steel by bacteria  

Energy Technology Data Exchange (ETDEWEB)

Mild steel was exposed to Pseudomonas sp. S9 or Serratia marcescens in synthetic seawater. An increase in corrosion resistance over that i natural seawater was monitored by electrochemical techniques. Biological analyses were performed to characterize the system. The inhibition effect also was observed when mild steel was coated with bacteria and then immersed in synthetic seawater. When specimens coated with bacteria were transferred to a natural seawater flow system, the inhibition effect disappeared during the first 2 weeks.

Hernandez, G.; Kucera, V.; Thierry, D.; Pedersen, A. (Swedish Corrosion Inst., Stockholm (Sweden)); Hermansson, M. (Univ. of Gothenburg (Sweden). Dept. of General and Marine Microbiology)

1994-08-01

174

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

175

Protective film formation of carbon steel surfaces for corrosion and deposit control in Heavy Water Plant, Manuguru (Paper No. 1.1)  

International Nuclear Information System (INIS)

Heavy Water Plant, Manuguru based on H2S-H2O bi-thermal chemical exchange process employs carbon steel as major material of construction for towers and piping. Several different phases of iron sulphide form as a result of interaction between aqueous H2S and carbon steel. Development of a procedure for formation of stable film on carbon steel as a preconditioning step was carried out based on work done by Heavy Water Division and the experiences of HWP, Kota. Heavy Water Plant, Manuguru was designed for carrying protective film formation of entire exchange unit including vessels, tanks, pipings etc. under dynamic conditions. This paper describes the procedure followed for the protective film formation of carbon steel surfaces at HWP, Manuguru. (author). 2 refs., 3 tabs., 2 figs

176

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

177

Corrosion resistance testing of high-boron-content stainless steels  

International Nuclear Information System (INIS)

Boron steels, i.e. stainless steels with boron contents of 0.2 to 2.25 wt.%, are employed in nuclear engineering for the manufacture of baskets or wells in which radioactive fissile materials are stored, mostly spent nuclear fuel elements. The resistance of such steels to intergranular corrosion and uniform corrosion was examined in the Strauss solution and in boric acid; the dependence of the corrosion rate of the steels on their chemical composition was investigated, and their resistance was compared with that of AISI 304 type steel. Corrosion resistance tests in actual conditions of ''wet'' compact storage (demineralized water or a weak boric acid solution) gave evidence that boron steels undergo nearly no uniform corrosion and, as electrochemical measurements indicated, match standard corrosion-resistant steels. Corrosion resistance was confirmed to decrease slightly with increasing boron content and to increase somewhat with increasing molybdenum content. (Z.S.). 3 tabs., 4 figs., 7 refs

178

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)

179

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

180

Corrosion of steel in hot brine  

International Nuclear Information System (INIS)

On an unalloyed steel, an oxide layer grows in aqueous solutions according to the parabolic time law. The corresponding velocity constant is independent of the chloride content of the solution. The velocity constant does not follow an Arrhenius line, but reaches a peak at a temperature of about 2500C. In the absence of chloride, the stationary corrosion rate in a neutral aqueous solution is always very low. An addition of a small quantity of chloride causes strong variations of the corrosion rate. This is to be explained by local corrosion. Holes covered by an oxide layer, however, grow towards depth only during a limited time. This effect leads to an increase in the average stationary corrosion rate particularly in concentrated chloride leaches. The design of a high-temperature apparatus for thermodynamic measurements on iron at temperatures of up to 2500C and pressures of up to 4 kbar is described. (orig./RB)

181

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

182

Corrosion inhibitor mechanisms on reinforcing steel in Portland cement pastes  

OpenAIRE

The mechanisms of corrosion inhibitor interaction with reinforcing steel are investigated in the present work, with particular emphasis on effects associated with corrosion inhibitors admixed into Portland cement paste. The principal objective in reinforcing steel corrosion inhibition for Portland cement concrete is observed to be preservation of the naturally passive steel surface condition established by the alkaline environment. Introduction of chloride ions to the steel surface accelerate...

Martin, Farrel James

2001-01-01

183

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

184

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

185

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

186

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

187

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

Energy Technology Data Exchange (ETDEWEB)

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.

Hwangbo, D.; Choi, S. J.; Lem, H. K.; Kim, Y. S. [Andong National University, Andong (Korea, Republic of)

2010-12-15

188

Corrosion behaviour of carbon steel in contact with bentonite under anaerobic condition  

Energy Technology Data Exchange (ETDEWEB)

Full text of publication follows: The geological disposal system of high-level radioactive waste (HLW) consists of vitrified waste, overpack, buffer material and surrounding rock. In this system, overpack is required to prevent the contact of groundwater from vitrified waste for 1000 years. The main factor limiting this function is corrosion due to the contact with groundwater infiltrated to buffer material which is the mixture of bentonite and sand. Carbon steel is selected as one of the candidate materials for overpacks in Japan as a corrosion allowance metal. The deep underground environment for geological disposal of HLW is expected to be relatively oxidizing condition at the initial stage of repository, but it will be returned to reducing as the consumption of oxygen by the corrosion of overpack and the redox reactions with the minerals in buffer material. It is necessary to understand the corrosion behaviour of carbon steel under such anaerobic condition for the lifetime prediction of carbon steel overpack. In this study, immersion tests of carbon steel in buffer material were performed in nitrogen atmosphere in which oxygen gas concentration was controlled less than 1 ppm. The corrosion rates of carbon steel were measured by weight loss of the specimens and the corrosion products were analysed by SEM, XRD and EPMA. For investigating the influence of welding of overpack, welded samples by electron-beam welding (EBW) were used in some of the tests. Synthetic sea water (SSW) and aqueous solutions containing bicarbonate ion and chloride ion were chosen as simulated groundwater. The results indicated that the corrosion form of carbon steel under anaerobic condition was uniform corrosion and no localised corrosion such as pitting, crevice corrosion was found within our experimental conditions. Ferrous carbonate such as FeCO{sub 3} or Fe{sub 2}(OH){sub 2}CO{sub 3} was identified as crystalline corrosion products by XRD. Although the corrosion rate was affected by test solution and buffer material design, the corrosion products film formed on the surface at 353 K were tight and very small corrosion rates less than 1{mu}m/y was obtained in any cases. While, the corrosion product at 323 K was not protective and larger corrosion rate of 2{mu}m/y was estimated. There was no influence of steel type and welding on the corrosion rate of carbon steel up to 3 years of immersion period. The average corrosion depth of carbon steel overpack was calculated to be {<=} 2 mm by extrapolating the obtained corrosion rate of {<=} 2{mu}m/y to 1000 years, and this estimation was well agreed with natural analogue data. (authors)

Naoki, Taniguchi; Susumu, Kawakami [Japan Nuclear Cycle Development Institute, Tokai-mura, Ibaraki (Japan); Manabu, Kawasaki; Mitsuru, Kubota [Inspection Development Corporation, Tokai-mura, Ibaraki (Japan)

2004-07-01

189

Corrosion behaviour of carbon steel in contact with bentonite under anaerobic condition  

International Nuclear Information System (INIS)

Full text of publication follows: The geological disposal system of high-level radioactive waste (HLW) consists of vitrified waste, overpack, buffer material and surrounding rock. In this system, overpack is required to prevent the contact of groundwater from vitrified waste for 1000 years. The main factor limiting this function is corrosion due to the contact with groundwater infiltrated to buffer material which is the mixture of bentonite and sand. Carbon steel is selected as one of the candidate materials for overpacks in Japan as a corrosion allowance metal. The deep underground environment for geological disposal of HLW is expected to be relatively oxidizing condition at the initial stage of repository, but it will be returned to reducing as the consumption of oxygen by the corrosion of overpack and the redox reactions with the minerals in buffer material. It is necessary to understand the corrosion behaviour of carbon steel under such anaerobic condition for the lifetime prediction of carbon steel overpack. In this study, immersion tests of carbon steel in buffer material were performed in nitrogen atmosphere in which oxygen gas concentration was controlled less than 1 ppm. The corrosion rates of carbon steel were measured by weight loss of the specimens and the corrosion products were analysed by SEM, XRD and EPMA. For investigating the influence of welding of overpack, welded samples by electron-beam welding (EBW) were used in some of the tests. Synthetic sea used in some of the tests. Synthetic sea water (SSW) and aqueous solutions containing bicarbonate ion and chloride ion were chosen as simulated groundwater. The results indicated that the corrosion form of carbon steel under anaerobic condition was uniform corrosion and no localised corrosion such as pitting, crevice corrosion was found within our experimental conditions. Ferrous carbonate such as FeCO3 or Fe2(OH)2CO3 was identified as crystalline corrosion products by XRD. Although the corrosion rate was affected by test solution and buffer material design, the corrosion products film formed on the surface at 353 K were tight and very small corrosion rates less than 1?m/y was obtained in any cases. While, the corrosion product at 323 K was not protective and larger corrosion rate of 2?m/y was estimated. There was no influence of steel type and welding on the corrosion rate of carbon steel up to 3 years of immersion period. The average corrosion depth of carbon steel overpack was calculated to be ? 2 mm by extrapolating the obtained corrosion rate of ? 2?m/y to 1000 years, and this estimation was well agreed with natural analogue data. (authors)

190

The assessment of corrosion type and corrosion rate of carbon steel in compacted bentonite  

International Nuclear Information System (INIS)

Carbon steel is one of the candidate materials for overpacks for high-level radioactive waste disposal in Japan. The estimation of corrosion allowance of carbon steel overpack needs to clarify the type of corrosion and the corrosion rate under repository conditions. The type of the corrosion occurring on overpacks depends on whether carbon steel is passivated or not. If carbon steel is passivated under repository conditions, localized corrosion such as pitting, crevice corrosion and stress corrosion cracking may occur under some conditions. On the other hand, if carbon steel is not passivated under repository conditions, general corrosion will occur. Passivation behavior and corrosion rate of carbon steel were investigated by electrochemical measurements under simulated repository conditions. The results of the measurements showed that carbon steel was hard to passivate in highly compacted bentonite. The immersion tests were carried out in compacted bentonite and average corrosion rates were measured from weight loss and the AC impedance of carbon steel specimens. The database of average corrosion rate were made from the data obtained by the weight loss technique. Based on the database of average corrosion rate in compacted bentonite, the relationship between average corrosion rates and test conditions were investigated. The average corrosion depth for 1000years was also estimated to be less than 5 mm. In order to simulate the accumulation of corrosion products after long term, the external current were supplied to carbon steel specimens. After the formation of corrosion products, corrosion rates were measured using AC impedance technique. The results of the measurements showed that the corrosion rate of carbon steel did not increase in the presence of corrosion products formed by external current supply. (author)

191

Galvanic corrosion between carbon steel 1018 and Alloy 600 in crevice with boric acid solution  

International Nuclear Information System (INIS)

This work dealt with the evaluation of galvanic corrosion rate in a corrosion cell having annular gap of 0.5 mm between carbon steel 1018 and alloy 600 as a function of temperature and boron concentration. Temperature and boron concentration were ranged from 110 to 300 .deg. C and 2000?10000 ppm, respectively. After the operating temperature of the corrosion cell where the electrolyte was injected was attained at setting temperature, galvanic coupling was made and at the same time galvanic current was measured. The galvanic corrosion rate decreased with time, which was described by corrosion product such as protective film as well as boric acid deposit formed on the carbon steel with time. From the galvanic current obtained as a function of temperature and boron concentration, it was found that the galvanic corrosion rate decreased with temperature while the corrosion rate increased with boron concentration. The experimental results obtained from galvanic corrosion measurement were explained by adhesive property of corrosion product such as protective film, boric acid deposit formed on the carbon steel wall and dehydration of boric acid to be slightly soluble boric acid phase. Moreover the galvanic corrosion rate calculated using initial galvanic coupling current instead of steady state coupling current was remarked, which could give us relatively closer galvanic corrosion rate to real pressurized water reactor

192

Corrosion resistance and mechanism of steel rebar coated with three types of enamel  

International Nuclear Information System (INIS)

Highlights: ? Three types of enamel coatings have different microstructures. ? All enamel coatings improve corrosion resistance of rebar to various extents. ? Unlike damaged FBE coating, enamel coatings experience no under-film corrosion. ? Enamel coatings are less sensitive to mechanical damage than FBE coating. ? Pure/double enamel coatings have higher corrosion resistance than mixed enamel coating. - Abstract: Corrosion resistances of steel rebar with different enamel coatings, and with fusion bonded epoxy coatings were investigated in 3.5 wt.% NaCl solution by Electrochemical Impedance Spectroscopy (EIS). The sensitivity to damage of the coatings was characterized and it was found that the pure and double enamel coatings can protect the steel rebar better than the mixed enamel coating due to their denser microstructures with isolated pores. Damaged enamel coating was locally corroded, whereas corrosion at a defect often undercut the epoxy coating. The intact epoxy coating offered better corrosion protection than the enamel coatings.

193

High performance corrosion-resistant structural steels  

Energy Technology Data Exchange (ETDEWEB)

A new corrosion-resistant structural steel named Duracorr was developed for low maintenance when compared to conventional structural steels. The new stainless steel is a dual phase composition between the established 12% Cr, ferritic T409 and martensitic T410 grades. Attractive combinations of hardness, strength, toughness, weldability and formability are derived from a microstructure that is a dual phase mixture of ferrite and martensite. The Duracorr composition, UNS S41003, provides for a microstructure of ferrite and austenite to be present throughout the hot rolling process. Cooling to room temperature causes transformation of the austenite to martensite. Subsequent tempering of the steel creates minimum mechanical properties of 275 MPa (40 ksi) yield strength and 455 MPa (66 ksi) tensile strength with room temperature longitudinal Charpy impact values typically greater than 34 J (25 ft-lbs).

Fletcher, F.B.; Ferry, B.N. [Lukens, Inc., Coatesville, PA (United States); Beblo, D.G. [Washington Steel Corp., PA (United States)

1995-12-31

194

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

195

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

196

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

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer 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. Black-Right-Pointing-Pointer A considerably high Si content (about 40 at%) is present in the anodic passive films formed on SMSSs in 0.5 M H{sub 2}SO{sub 4} solution. Black-Right-Pointing-Pointer The high protectiveness of the anodic passive film formed on SMSSs in 0.5 M H{sub 2}SO{sub 4} solution results from a protective film consisting of a (Fe, Cr)-mixed silicate. Black-Right-Pointing-Pointer The SMSSs exhibited higher corrosion resistance than SS 304 in highly oxidizing environments. Black-Right-Pointing-Pointer 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 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.

Della Rovere, C.A., E-mail: carlosdrovere@gmail.com [Department of Materials Engineering, Federal University of Sao Carlos Rodovia Washington Luis, Km 235, 13565-905 Sao Carlos, SP (Brazil); Alano, J.H.; Silva, R.; Nascente, P.A.P. [Department of Materials Engineering, Federal University of Sao Carlos Rodovia Washington Luis, Km 235, 13565-905 Sao Carlos, SP (Brazil); Otubo, J. [Division of Mechanical Engineering, Technological Institute of Aeronautics Praca Marechal Eduardo Gomes, 50, Vila das Acacias, 12228-900 Sao Jose dos Campos, SP (Brazil); Kuri, S.E. [Department of Materials Engineering, Federal University of Sao Carlos Rodovia Washington Luis, Km 235, 13565-905 Sao Carlos, SP (Brazil)

2012-04-16

197

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.

198

Melting of corrosion resistant steel in converter  

International Nuclear Information System (INIS)

A technique permitting to melt chromium-nickel low-carbon corrosion resistant steel in a converter type aggregate by the method of gas-acid refining is developed. The metal temperature is regulated using the combined elasting, cooling agents and changing the gas-acid mixture content. A steel temperature does not exceed 1770 deg C. A chromium ore ad-- dition in amounts of 20-28 kg/t permits to increase a degree of chromium usage by 4% and to decrease melting loss by 2.0-2.2%

199

To the corrosion of austenitic steels in sodium loops  

International Nuclear Information System (INIS)

This report describes the comparison between experimental corrosion and calculated corrosion effects on austenitic steels exposed to liquid sodium. As basis for the calculations served a diffusion model. The comparison showed that the model is able to predict the corrosion effects. In addition the model was used to calculate the corrosion effect along an actual fuel rod. (orig.)

200

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.

201

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

202

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

203

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

204

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

205

Evaluation of Performance of Grout Materials in Protection of Prestressing Steel  

Directory of Open Access Journals (Sweden)

Full Text Available Prestressing cables are widely used in huge constructions like buildings and bridges. Corrosion of prestressing steel is more dangerous than the corrosion of reinforcing steel in concrete. Stress corrosion is propagated due to corrosion initiation in prestressing steel under stressed condition. Corrosion resistance of the prestressing steel depends upon the grout material. In this investigation three types of grout materials namely cement grout with non-shrinking admixture, polyurethane foam and epoxy grout were assessed for its suitability within the prestressing cable duct. The performance of grout materials to protect against prestressing steel corrosion was evaluated by different electrochemical techniques such as OCP measurements, anodic polarisation test and impressed voltage technique. The mechanical property of the different grout materials were test at room and elevated temperature. Among the three grouts, epoxy based grout system showed better corrosion resistance properties.

K. Kumar, M.S. Karthikeyan and N. Palaniswamy

2008-03-01

206

Crevice corrosion resistances of stainless steels in marine environments  

International Nuclear Information System (INIS)

This paper studies the effects of minor elements on crevice corrosion resistances of stainless steels ranging from AISI 316 to the 6% molybdenum austenitic stainless steels in order to define an alloy composition suitable for seawater service and, in particular, for resistance to crevice corrosion. Overall, the results indicate the feasibility of significantly improving the corrosion resistance of the high-alloy austenitic stainless steels to the point where they would be suitable for seawater service

207

Corrosion of austenitic steel in leakage lithium  

Energy Technology Data Exchange (ETDEWEB)

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 Al{sub 2}O{sub 3} 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 Li{sub 3}N, LiOH, and Li{sub 2}O{sub 2} environments. Because Li{sub 2}O{sub 2} is not stable according to the chemical equilibrium calculations, corrosion by Li{sub 3}N and LiOH needs to be considered in high-temperature lithium applications.

Furukawa, Tomohiro, E-mail: furukawa.tomohiro@jaea.go.jp; Hirakawa, Yasushi; Kato, Shoichi

2013-10-15

208

Protection of mild steel corrosion with Schiff bases in 0.5 M H{sub 2}SO{sub 4} solution  

Energy Technology Data Exchange (ETDEWEB)

Three new Schiff bases, viz., N,N'-ethylen-bis (salicylideneamino) [S{sub 1}], N,N'-isopropenyl-bis (salicylideneamino) [S{sub 2}], and N-acetylacetone imine, N'-(2-hydroxybenzophenone imine) ortho-phenyl en [S{sub 3}] have been investigated as corrosion inhibitors for mild steel in 0.5 M H{sub 2}SO{sub 4} using Tafel polarization and electrochemical impedance spectroscopy (Ei). The three Schiff bases function as good inhibitors reaching inhibition efficiencies of {approx}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.

Hosseini, M.G. [Electrochemistry Research Laboratory, Physical Chemistry Department, Chemistry Faculty, Tabriz University (Iran, Islamic Republic of)]. E-mail: mg-hosseini@tabrizu.ac.ir; Ehteshamzadeh, M. [Department of Materials Science and Engineering, Tarbiat Modarres University, Tehran (Iran, Islamic Republic of); Shahrabi, T. [Department of Materials Science and Engineering, Tarbiat Modarres University, Tehran (Iran, Islamic Republic of)

2007-03-01

209

Nitrogen addition and localized corrosion behaviour of austenitic stainless steels  

International Nuclear Information System (INIS)

Nitrogen as an alloying element has been reported to improve the localized corrosion resistance, particularly pitting, crevice and intergranular corrosion of austenitic stainless steels in chloride containing aqueous environments. The authors highlight the corrosion behaviour of nitrogen-alloyed (up to 0.56 wt%) austenitic stainless steels and compared the studies carried out by several groups. The influence of various metallurgical variables including cold working, thermal ageing, grain size and surface treatment on the pitting corrosion behaviour of the nitrogen-alloyed austenitic stainless steels is addressed. The mechanism by which nitrogen enhanced the corrosion resistance is elucidated with the help of results obtained using electrochemical and surface analytical techniques. The role of nitrogen on the formation of passive films and the semiconducting nature of passive film with nitrogen addition, are discussed to understand the corrosion resistance offered by the passive films with increasing nitrogen addition. The differences in the localized corrosion behaviour between various nitrogen alloyed stainless steels are highlighted. (author)

210

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

211

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.

212

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

213

REDUCED-POLLUTION CORROSION-PROTECTION SYSTEMS  

Science.gov (United States)

Coating systems, designed to protect metallic components against corrosive attack using environmentally compatible materials and processes, were evaluated as potential alternatives for their higher polluting counterparts. Viable replacements were established for cyanide cadmium, ...

214

Corrosion protection of Koeberg nuclear power station  

International Nuclear Information System (INIS)

Koeberg is South Africa's first nuclear power station. This paper describes the manner in which a corrosion protection specification for the project was compiled, the types of coatings used and the particular requirements of this project

215

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

216

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

217

Experiencies of corrosion and corrosion protection in seawater-cooling systems in the Nordic countries  

International Nuclear Information System (INIS)

This report summarizes the experience of the corrosion resistance of pumps, heat exchangers, valves, and pipings in different seawater-cooling system. For pumps and heat exchangers the experience has been so extensive that a clear picture of todays status can be given. Owing to more scanty data concerning valves and pipes the survey of the corrosion in these components is less well substantiated. The most common pumps in the cooling systems of power stations are vertically extended shaft pumps. To counteract corrosion on column and casing with organic surface coating and on stainless steel shafts and impellers under shutdown conditions, these should be provided with internal and external cathodic protection. The experience of tin and aluminium bronzes in impellers and shafts in such pumps has been so poor - erosion and cavitaion damage - that a change has usually been made to preferentially ferritic-austenitic Mo-alloyd stainless steels. The combination of stainless steel/Ni-Resist 2 D has been found unsatisfactory owing to the occurrence of galvanic corrosion on the latter material. For heat exchangers, titanium has proved to be far and away the best choice. In the optimal blanket solution for a titanium heat exchangers the tubes are seal-welded to tube sheets of explosion-bonded titanium clad steel. For retubing of old condensers a similar procedure with tubes of high-alloy stainless steel in tube sheets of stainless clad steel is of economic interest. The effect of chlorination of the cooling water, however, remains to be clarified before such a procedure can be unreservedly recommended. Pipings of rubber-lined carbon steel or with thick coatings of solvent-free opoxy resin have shown very good corrosion resistance. Tar-epoxy-resin-coated pipes, however, should usually be provided with internal cathodic protection. Cement-lined carbon steel pipes are used with varying results in the offshore industry. Recently, however, pipes of the high slloy stainless steel 254 SMO have also come into use for similar purposes. (Author)

218

Tantalum films for protective coatings of steel  

International Nuclear Information System (INIS)

Deposition of tantalum films for protective coatings on steel by DC magnetron sputtering have been investigated. Conditions resulting in the deposition of bcc and tetragonal phases of tantalum and the evolution of the phase composition and crystallinity during the film growth from nanometers to tens of micrometers are described. Heating the substrates to only 400 deg. C resulted in the growth of pure bcc phase tantalum, which is tough and ductile and thus preferred for protective coatings, while lower temperatures promote nucleation and growth of the hard and brittle tetragonal phase. Adhesion tests by scratching with a diamond tip showed that while well adhering coatings of both phases can be obtained, the tetragonal phase films develop cracks under load, well below the critical value that results in delamination. This has important implications for application of tantalum films for protection against corrosion of steel elements subjected to mechanical stress and wear, as the cracks would locally expose the substrate to the surrounding environment. With proper choice of deposition conditions and moderate heating that does not compromise the steel properties, coatings of the preferred bcc phase of tantalum with excellent adhesion can be deposited by DC magnetron sputtering

219

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

220

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.

221

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-01-15

222

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

223

Corrosion modeling for carbon steel under oxygen depleted underground environment  

International Nuclear Information System (INIS)

In the oxygen depleted underground neutral aqueous solution environment, carbon steel reacts with H2O, producing H2 gas and forming corrosion film on the steel surface. Corrosion rate is controlled by diffusion of reaction species through corrosion film. Diffusion constants of some species working in the corrosion process were obtained from literatures. However, no data were found on the diffusion constant of H2O in iron oxides, which were estimated based on an appropriate assumption. Mass transfer model for the corrosion rate was used to simulate the corrosion rate of carbon steel. Liquid phase diffusion model of Fe2+ or H2O through pores in the corrosion film and solid phase diffusion model of H2O through corrosion film itself were examined by simulation using the spread sheet of Excel. Change in corrosion current density and corrosion loss with time and pH and temperature dependence of corrosion current density were examined. By comparing simulated results with the experimental data, it was suggested that the solid phase diffusion of H2O in the corrosion film controls the corrosion rate of carbon steel in oxygen depleted environment. (author)

224

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

Science.gov (United States)

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 °C and 550 °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 °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 °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 Fe 3O 4 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.

Zhang, Jinsuo; Li, Ning; Chen, Yitung; Rusanov, A. E.

2005-01-01

225

Aminopyrimidine derivatives as inhibitors for corrosion of 1018 carbon steel in nitric acid solution  

International Nuclear Information System (INIS)

The effect of some aminopyrimidine derivatives on the corrosion of 1018 carbon steel in 0.05 M HNO3 solution was studied using weight loss and polarization techniques. The percentage inhibition efficiency was found to increase with increasing concentration of inhibitor and with decreasing temperature. The addition of KI to aminopyrimidine derivatives enhanced the inhibition efficiency due to synergistic effect. The inhibitors are adsorbed on the steel surface according to Temkin isotherm. Some thermodynamic functions were computed and discussed. It was found that the aminopyrimidine derivatives provide a good protection to steel against pitting corrosion in chloride containing solutions

226

Joint effect of temperature, stress states and sulfur ions on the CO2 corrosion behavior of N80 tubing steel  

Directory of Open Access Journals (Sweden)

Full Text Available The joint influence of solution temperature, stress states and sulfur ions on the CO2 corrosion behavior of N80 tubing steel, were investigated by using electrochemical impedance spectroscopy (EIS. The results showed that the addition of sulfur ions into the solution and with the introducing of stress into carbon steel can decrease the protective effect of the corrosion scale on the substrate at low temperature; and the protective effect enhances at high temperatures. The corrosion scale formed on N80 steel in stratum water containing sulfur ions are mainly consisted of FeCO3 and FeS.

J. B. Li, X. Hou, M.S Zheng, J. W. Zhu

2007-08-01

227

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

228

Evaluation of the susceptibility to pitting corrosion of structural steels, including steels with modified surface  

International Nuclear Information System (INIS)

Although the low alloy ferrite-perlite and bainite-martensite steels mostly undergo the general corrosion, pitting corrosion occurring under certain conditions jeopardizes the safety of installations, causing perforation of walls or initiation of crack. On the basis of electrochemical, corrosion and microscopic examinations, the conditions simulating typical industrial corrosion environments, containing Cl- ions have been selected, to which the parts of machines, devices and installation are subjected. The test parameters provide the preferential pitting corrosion without prevailing general corrosion, and provide the similar type of corrosion of different kinds of ferrite-perlite and bainite-martensite steels, including steels with modified surface layer. The proposed express method allows to evaluate the susceptibility to pitting corrosion and to evaluate the effect of surface modification on susceptibility to pitting corrosion in environments containing Cl- ions. The method may be applied for the proper selection of materials exploited under pitting corrosion conditions and for preparation of precorroded samples for mechanical testing. (author)

229

Corrosion Behavior of Nitrogen Ion Implanted Stainless Steel  

International Nuclear Information System (INIS)

The corrosion behavior of nitrogen ion implanted 440C stainless steel was studied as a practical application of ion implantation. 440C stainless steel was subjected to the same implantation condition which showed the significant improvement of corrosion resistance of a high purity iron. The composition and structure of implanted layer were examined. The corrosion tests of the samples were performed in deaerated 1N H2SO4 and 0.1M NaCl aqueous solution using a potentiodynamic polarization method. The corrosion mechanisms of nitrogen ion implanted 440C stainless steel were investigated

230

Understanding corrosion via corrosion product characterization: II. Role of alloying elements in improving the corrosion resistance of Zn-Al-Mg coatings on steel  

International Nuclear Information System (INIS)

Highlights: ? Origins of better corrosion resistance of ZnAlMg coatings than galvanized steel. ? Comparative study of corrosion products formed on ZnAlMg, ZnMg and Zn coatings. ? Modeling of dissolution and precipitation stages of corrosion. ? At early stages Mg stabilizes protective zinc basic salts during dry-wet cycling. ? At later stages Al dissolves at high pH forming protective layered double hydroxides. - Abstract: Corrosion products are identified on Zn, ZnMg and ZnAlMg coatings in cyclic corrosion tests with NaCl or Na2SO4 containing atmospheres. For Mg-containing alloys the improved corrosion resistance is achieved by stabilization of protective simonkolleite and zinc hydroxysulfate. At later stages, the formation of layered double hydroxides (LDH) is observed for ZnAlMg. According to thermodynamic modeling, Mg2+ ions bind the excess of carbonate or sulfate anions preventing the formation of soluble or less-protective products. A preferential dissolution of Zn and Mg at initial stages of corrosion is confirmed by in situ dissolution measurement. The physicochemical properties of different corrosion products are compared.

231

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

232

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

2014-12-01

233

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

234

49 CFR 192.463 - External corrosion control: Cathodic protection.  

Science.gov (United States)

... false External corrosion control: Cathodic protection. 192.463 Section 192.463 Transportation...192.463 External corrosion control: Cathodic protection. (a) Each cathodic protection system required by this subpart must...

2010-10-01

235

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

236

The anaerobic corrosion of carbon steel in concrete  

International Nuclear Information System (INIS)

This is the final report of a 2 year programme aimed at (1) determining the rate of anaerobic corrosion of steel in concrete, (2) investigating the nature of the corrosion products formed on carbon steel embedded in cementitious material under anaerobic conditions and (3) evaluating the effect of hydrogen over-pressures on the rate of anaerobic corrosion. All experiments have been carried out at temperatures in the range 20-300C, ie ambient conditions. 4 refs.; 19 figs.; 6 tabs

237

Inhibition properties of self-assembled corrosion inhibitor talloil diethylenetriamine imidazoline for mild steel corrosion in chloride solution saturated with carbon dioxide  

International Nuclear Information System (INIS)

Highlights: •Corrosion inhibitor talloil diethylenetriamine imidazoline effectively protects mild steel from CO2 corrosion. •Quartz crystal microbalance measurements were used to the investigate kinetics of corrosion inhibitor adsorption. •Adsorption of talloil diethylenetriamine imidazoline can be described by Langmuir adsorption isotherm. -- Abstract: The inhibition effect of talloil diethylenetriamine imidazoline (TOFA/DETA imidazoline) on corrosion of mild steel in chloride solutions saturated with CO2 was investigated by weight loss measurements (WL) and atomic force microscopy (AFM). Adsorption mechanism and kinetics of self-assembled (TOFA/DETA imidazoline) monolayers formation on gold were studied using the quartz crystal microbalance measurements (QCM). WL and AFM results demonstrated that TOFA/DETA imidazoline can effectively protect mild steel surface from corrosion. QCM measurements shown that the adsorption of TOFA/DETA imidazoline onto gold follows Langmuir adsorption isotherm and further investigation of the adsorption process will be carried out on a corroding metal surface

238

Inhibition of mild steel corrosion by thiourea derivatives  

International Nuclear Information System (INIS)

The decommissioning implies the removing of the contamination from the component surfaces using: the mechanical action, the chemical and electrochemical cleaning solutions and other procedures. A decontamination process is applied using a solution containing 2M formic acid, 0.1M formaldehyde and some inhibitors. These inhibitors must maintain between the reasonable limits the rates of two concurrent processes: the dissolution of deposits and the attack on the base metal. In this aim, the following thiourea derivatives have been used as corrosion inhibitors of mild steel in the decontamination processes executed at relative high temperature (85-90 deg. C): thiourea, Nphenylthiourea and N, N'-diphenylthiourea. The concentrations used in the case of all inhibitors have been comprised between 3.10-4M and 3.10-3M. To evaluate their efficiency was used mainly the potentiodynamic method. Applying this method, their efficiency was determined by two methods: from Tafel slopes and from polarization resistance (Rp). In presence of these compounds high inhibition efficiency (I.E.) in the decommissioning solutions have been recorded, their efficiency varying with their concentrations and molecular weights. As result of our tests, we established the following rank in which decreases their efficiency: N, N'-diphenylthiourea >N-phenylthiourea> thiourea The protectiveness accorded by these corrosion inhibitors will permit simultaneous decontamination owill permit simultaneous decontamination of mild steel and stainless steels in same solution in identical conditions

239

Experiences of corrosion and corrosion protection in seawater systems in the Nordic countries  

International Nuclear Information System (INIS)

A summary is given of the experience of the corrosion resistance of pumps, heat exchangers, valves and pipings in different seawater cooling systems in Scandinavia, including power reactor cooling systems in Finland and Sweden. For pumps and heat exchangers the experience has been so extensive that a clear picture of today's standing can be given. Owing to scanty data concerning valves and pipes, the survey of the corrosion in these components is less well supported. Vertically extended centrifugal pumps are the pumps in general use in power plant cooling systems. To counteract corrosion on pump riser and pump casing having an organic surface coating, and on stainless steel shafts and impellers, these components should be provided with internal and external cathodic protection. For tube and plate type heat exchangers, titanium has proved to be the best material choice. Rubber-enclosed carbon steel pipings, or pipings having a thick coating of epoxy plastic, have shown very strong corrosion resistance in power plant seawater cooling systems. Valves in seawater systems have primarily been affected by corrosion due to poorly executed or damaged organic coating on cast iron. Different seawater-resistant bronzes (red bronze, tin bronze and aluminium bronze) are therefore preferable as valve materials

240

Results of investigation into corrosion resistance of certain structural steels and nickel in fluoride products of fast reactor fuel reprocessing  

International Nuclear Information System (INIS)

The results of investigation into corrosion resistance of carbon steel (steel-3), steel-Kh18N10T and nickel (NP-1) in the spent fuel reprocessing products of BOR-60 reactor by the fluoride volatility method. The effect of chemical medium, temperature and time on metal corrosion is considered. The effect of gamma radiation on corrosion resistance of steels and nickel in fluoride salts is estimated. It is shown that the corrosion of investigated materials increases with temperature and moisture of the environment. The formation of protective films on the metal surface after the durable contact with the fluoride salts is discovered. The protective properties of these films depend on their structure and environment conditions. The investigation into metal corrosion properties provides the recommendations on conditions of their utilization as construction materials in the fluoride volatility reprocessing of spent fuel

241

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

242

Corrosion behaviour of sintered duplex stainless steels  

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-07-01

243

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

244

In-situ electrochemical study of corrosion of steel and aluminum/steel couples during cyclic corrosion test  

Energy Technology Data Exchange (ETDEWEB)

Use of aluminum alloys for automotive applications is growing steadily. Galvanic corrosion is a major concern for those alloys. Because of the predominate use of steels in the automotive industry, the majority of accelerated test procedures commonly accepted by the industry are designed for cosmetic corrosion and perforation of steels. SAE 52334 and Ford Arizona Proving Ground (Ford APG) tests are two examples. Adopting those tests for galvanic corrosion of Al alloys without any fundamental understanding of the process may lead to misleading results. In this paper, electrochemical studies were conducted to examine the acceleration effects of several parameters on different types of corrosion. Galvanic corrosion of aluminum 6111 alloy and cold rolled steel (Al/ CRS) couples and general corrosion of cold rolled steel substrates were studied.

Gao, G. [Ford Motor Co., Dearborn, MI (United States)

1998-12-31

245

Corrosion study of bare and coated stainless steel  

Science.gov (United States)

A program was conducted at Kennedy Space Center from February 1968 to February 1971 to evaluate the performance of austenitic stainless steel alloys used in fluid systems lines. For several years, there had been numerous failures of stainless steel hardware caused by pitting and stress corrosion cracking. Several alloys were evaluated for effectiveness of certain sacrificial-type protective coverings in preventing corrosion failures. Samples were tested in specially designed racks placed 91 meters (100 yards) above high-tide line at Cape Kennedy. It is concluded that: (1) unprotected tubing samples showed evidence of pitting initiation after 2 weeks; (2) although some alloys develop larger pits than others, it is probable that the actual pitting rate is independent of alloy type; (3) the deepest pitting occurred in the sheltered part of the samples; and (4) zinc-rich coatings and an aluminum-filled coating have afforded sacrificial protection against pitting for at least 28 months. It is believed that a much longer effective coating life can be expected.

Morrison, J. D.

1972-01-01

246

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

247

Comparative investigation of corrosion resistance of steel reinforcement in alinite and Portland cement mortars  

Energy Technology Data Exchange (ETDEWEB)

The corrosion resistance of steel-reinforced mortar specimens made from alinite cement was investigated using ordinary Portland cement (OPC) specimens as reference. The specimens were prepared and exposed in three different environments: continuous exposure in tap water, interrupted exposure in tap water, and interrupted exposure in 3.5% NaCl solution. The steel weight loss and the half cell potential were measured vs. exposure time, up to the age of 12 months. Pore solution extraction and analysis and porosity determination were also performed. In continuous exposure in tap water, alinite cement provided adequate protection against corrosion. In interrupted exposure in tap water, a higher corrosion was observed for alinite cement compared to OPC. In the case of interrupted exposure in 3.5% NaCl solution, the simultaneous action of free chlorides and oxygen resulted in the depassivation of steel reinforcing bars in alinite and Portland cement mortars, and led to severe corrosion effect.

Kostogloudis, G.C.; Kalogridis, D.; Ftikos, C. [National Technical Univ., Athens (Greece); Malami, C.; Georgali, B.; Kaloidas, V. [Heracles General Cement Co., Athens (Greece)

1998-07-01

248

Inhibition of salt precipitation, corrosion and corrosion fatigue of steel in neutral environments  

International Nuclear Information System (INIS)

Processes of salt precipitation, corrosion under dynamic and static conditions, are studied as well as corrosion fatigue of 20 and 40Kh steels in neutral aqueous media without and with the addition of compounds of several classes. The solution of calcium bicarbonate with the initial concentration [Ca(HCO3)2]=1.3 g/l and 3% NaCl solution in distilled water are used for investigation. The effectiveness index of salt precipitation inhibitor is determined by the change in the rate of calcium bicarbonate transformation into carbonate. The combination of results obtained permits to make the conclusion that tripolyphosphate and pyrophosphoric acid are rather perspective inhibitors of complex effect with low protective concentrations

249

Corrosion behavior of carbon steel in compacted bentonite saturated with simulated groundwater under anaerobic condition  

International Nuclear Information System (INIS)

Immersion tests of carbon steel were performed in compacted bentonites saturated with simulated groundwater for a 10-year duration under anaerobic condition. The ferrous carbonates were identified as the corrosion product by XRD and XPS analyses in most of the test cases. The amount of corrosion in high carbonate concentration was smaller than those under the other test conditions throughout the test periods. Although the corrosion rate at 50degC was initially smaller than that at 80degC, it resulted in larger value after several years. The effects of carbonate content and temperature on the long-term corrosion rate seemed to be correlated to the behavior of deposition of the iron carbonate on the surface of carbon steel. Additionally, the correlation between initial corrosion rate and the protectiveness of corrosion product film was examined. Except for high carbonate condition, as the initial corrosion rate was larger, the corrosion product film tended to become more protective. The long-term corrosion depth was estimated by the extrapolation of the laboratory test results. The range of the estimated value was in good agreement with that of archaeological analogue data. (author)

250

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

251

Mesoporous silica nanoparticles for active corrosion protection.  

Science.gov (United States)

This work presents the synthesis of monodisperse, mesoporous silica nanoparticles and their application as nanocontainers loaded with corrosion inhibitor (1H-benzotriazole (BTA)) and embedded in hybrid SiOx/ZrOx sol-gel coating for the corrosion protection of aluminum alloy. The developed porous system of mechanically stable silica nanoparticles exhibits high surface area (?1000 m2·g(-1)), narrow pore size distribution (d?3 nm), and large pore volume (?1 mL·g(-1)). As a result, a sufficiently high uptake and storage of the corrosion inhibitor in the mesoporous nanocontainers was achieved. The successful embedding and homogeneous distribution of the BTA-loaded monodisperse silica nanocontainers in the passive anticorrosive SiOx/ZrOx film improve the wet corrosion resistance of the aluminum alloy AA2024 in 0.1 M sodium chloride solution. The enhanced corrosion protection of this newly developed active system in comparison to the passive sol-gel coating was observed during a simulated corrosion process by the scanning vibrating electrode technique (SVET). These results, as well as the controlled pH-dependent release of BTA from the mesoporous silica nanocontainers without additional polyelectrolyte shell, suggest an inhibitor release triggered by the corrosion process leading to a self-healing effect. PMID:21344888

Borisova, Dimitriya; Möhwald, Helmuth; Shchukin, Dmitry G

2011-03-22

252

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

253

Flow Assisted Corrosion and Erosion-Corrosion of RAFM Steel in Liquid Breeders  

International Nuclear Information System (INIS)

Full text: Study on flow assisted corrosion (FAC) and erosion-corrosion of RAFM JLF-1 steel (Fe-9Cr-2W-0.1C) in liquid breeders of Li, Pb-17Li and Flinak was carried out. It was found that the alloying element of Fe and Cr in the JLF-1 steel was commonly dissolved into these melts. The compatibility model of the JLF-1 steel in liquid breeders was developed. The mass loss of the specimens in the corrosion experiments was evaluated by the model. The effect of erosion-corrosion on the total mass loss of the steel in the liquid metals could be larger than that of FAC estimated by mass transfer calculation. The mass loss of the steel by electrochemical corrosion might be larger than that by the FAC in the Flinak. (author)

254

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

255

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

256

Sensitization-induced localized corrosion in austenitic stainless steels  

International Nuclear Information System (INIS)

Sensitization-induced localized corrosion can be broadly classified into two categories, namely, intergranular corrosion (IGC) and intergranular stress corrosion cracking (IGSCC). These two forms of corrosion affect several grades of austenitic stainless steels and nickel based alloys, and are commonly observed in power, chemical and petrochemical industries. Majority of corrosion failures of critical austenitic stainless steel components in these industries can be attributed to IGC and IGSCC. It is therefore essential to monitor the extent and rate of these localized forms of corrosion periodically. This paper will discuss the following issues related to sensitization induced localized corrosion in austenitic stainless steels: low temperature sensitization (LTS) in austenitic stainless steels, modification to ASTM test for evaluation of IGC susceptibility in austenitic stainless steels and NDT methods (UT and ECT) for monitoring IGC and IGSCC in austenitic stainless steels. Irradiation-assisted stress corrosion cracking (IASCC), attributed to solute segregation (Si, P) and chromium depletion at grain boundaries induced by irradiation will also be discussed. (author)

257

Corrosion behavior of duplex stainless steel in sulphuric acid  

International Nuclear Information System (INIS)

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

258

Effect of radiation on corrosion and irradiation-assisted stress corrosion cracking of austenitic stainless steels  

International Nuclear Information System (INIS)

This paper presents the processes occurring in corrosion cracking of austenitic steels after irradiation, effects of these processes on the environment and the mechanical properties, as well as radiation-induced segregation phenomenon: the influence of neutron irradiation on the microstructure and microchemical changes resulting in a decrease of corrosion resistance and the chemical activity of the corrosive environment. It presents the opportunity to simulate the microstructural and microchemical changes occurring in reactor-irradiated austenitic steels using charged particles (ions, protons, electrons)

259

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

OpenAIRE

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...

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

2012-01-01

260

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

261

Corrosion of ODS steels in lead-bismuth eutectic  

International Nuclear Information System (INIS)

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

262

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

Directory of Open Access Journals (Sweden)

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

Ayo Samuel AFOLABI

2007-01-01

263

Factors and mechanisms affecting corrosion of steel in concrete  

International Nuclear Information System (INIS)

Atomic power plants possess reinforced concrete structures which are exposed to sea water or sea atmosphere. Sea water or its surrounding environment contain very corrosive species which cause corrosion of metal in concrete. It should be mentioned that corrosion of steel in concrete is a complex problem that is not completely understood. Some of the factors which influence the corrosion mechanism and can be related to the pore solution composition is discussed. Chloride ion caused problems are the main source of the corrosion damage seen on the reinforced concrete structures. Corrosion rate in concrete varies and depends on the way chloride ion diffuses into concrete. In addition, the associated cations can influence diffusion of chloride into concrete. The type of portland cement and also the concrete mix design all affect the corrosion behaviour of steel in concrete

264

Electrochemical Studies of Stainless Steel Corrosion in Peroxide Solutions  

Directory of Open Access Journals (Sweden)

Full Text Available 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 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

2012-03-01

265

Corrosion-resistant Foamed Cements for Carbon Steels  

Energy Technology Data Exchange (ETDEWEB)

The cementitious material consisting of Secar #80, Class F fly ash, and sodium silicate designed as an alternative thermal-shock resistant cement for the Enhanced Geothermal System (EGS) wells was treated with cocamidopropyl dimethylamine oxide-based compound as foaming agent (FA) to prepare numerous air bubble-dispersed low density cement slurries of and #61603;1.3 g/cm3. Then, the foamed slurry was modified with acrylic emulsion (AE) as corrosion inhibitor. We detailed the positive effects of the acrylic polymer (AP) in this emulsion on the five different properties of the foamed cement: 1) The hydrothermal stability of the AP in 200 and #61616;C-autoclaved cements; 2) the hydrolysis-hydration reactions of the slurry at 85 and #61616;C; 3) the composition of crystalline phases assembled and the microstructure developed in autoclaved cements; 4) the mechanical behaviors of the autoclaved cements; and, 5) the corrosion mitigation of carbon steel (CS) by the polymer. For the first property, the hydrothermal-catalyzed acid-base interactions between the AP and cement resulted in Ca-or Na-complexed carboxylate derivatives, which led to the improvement of thermal stability of the AP. This interaction also stimulated the cement hydration reactions, enhancing the total heat evolved during cement’s curing. Addition of AP did not alter any of the crystalline phase compositions responsible for the strength of the cement. Furthermore, the AP-modified cement developed the porous microstructure with numerous defect-free cavities of disconnected voids. These effects together contributed to the improvement of compressive-strength and –toughness of the cured cement. AP modification of the cement also offered an improved protection of CS against brine-caused corrosion. There were three major factors governing the corrosion protection: 1) Reducing the extents of infiltration and transportation of corrosive electrolytes through the cement layer deposited on the underlying CS surfaces; 2) inhibiting the cathodic reactions at the corrosion site of CS; 3) extending the coverage of cement over CS surfaces; and, 4) improving the adherence of the cement to CS surfaces. Thus, the CS’s corrosion rate of 176 milli inch/per year (mpy) for 1 wt% FA-foamed cement without AP was considerably reduced to 69 mpy by adding only 2 wt% AP. Addition of AP at 10 wt% further reduced this rate to less than 10 mpy.

Sugama T.; Gill, S.; Pyatina, T., Muraca, A.; Keese, R.; Khan, A.; Bour, D.

2012-12-01

266

Corrosion of vessel steel during its interaction with molten corium  

International Nuclear Information System (INIS)

An experimental examination of the cooled vessel steel corrosion during the interaction with molten corium is presented. The experiments have been conducted on 'Rasplav-2' test facility and followed up with physico-chemical and metallographic analyses of melt samples and corium-specimen ingots. The results discussed in the first part of the paper have revealed specific corrosion mechanisms for air and inert atmosphere above the melt. Models have been proposed based on this information and approximate curves constructed for the estimation of the corrosion rate or corrosion depth of vessel steel in conditions simulated by the experiments

267

Corrosion induced by cathodic hydrogen in 2205 duplex stainless steel  

Science.gov (United States)

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.

2011-05-01

268

Corrosion induced by cathodic hydrogen in 2205 duplex stainless steel  

International Nuclear Information System (INIS)

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.

269

Corrosion of vessel steel during its interaction with molten corium  

International Nuclear Information System (INIS)

This paper is concerned with corrosion of a cooled vessel steel structure interacting with molten corium in air and neutral (nitrogen) atmospheres during an in-vessel retention scenario. The data on corrosion kinetics at different temperatures on the heated steel surface, heat flux densities and oxygen potential in the system are presented. The post-test physico-chemical and metallographic analyses of melt samples and the corium-specimen ingot have clarified certain mechanisms of steel corrosion taking place during the in-vessel melt interaction

270

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

271

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

Energy Technology Data Exchange (ETDEWEB)

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.

Fasuba, O.A.; Yerokhin, A., E-mail: A.Yerokhin@sheffield.ac.uk; Matthews, A.; Leyland, A.

2013-08-15

272

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

273

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.)

274

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

275

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

276

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

277

Corrosion resistance of Si- and Al-rich steels in flowing lead bismuth  

Science.gov (United States)

Corrosion resistance of Si- and Al-rich steels in lead-bismuth flow was studied experimentally. The specimens of SUH3 (10Cr-1Mo-2Si), NTK04L (18Cr-3Al) and Recloy10 (18Cr-1Al-1Si) were exposed to flowing lead-bismuth for 500-2000 h. After the exposure, metallurgical analysis of their surfaces and weight loss measurement of the specimens were carried out. The surface of the Si-rich steels, SUH3, was smooth with no liquid metal corrosion. Double-oxide layers were observed on the surface of SUH3 steel, where an inner layer might serve as a barrier for the liquid metal corrosion attack, while the outer layer could detach from the surface. An initial metallic luster of the surfaces remained on NTK04L and Recloy 10 steels after the exposure. An Al-rich single layer was formed and stuck on the steel surfaces. This layer protected the steel matrix from the corrosion. The weight losses of these Al-rich steels, NTK04L and Recloy10, in the exposure for the time up to 2000 h were negligibly small.

Kondo, Masatoshi; Takahashi, Minoru

2006-09-01

278

Innovative steels for structural and corrosion resistance applications  

OpenAIRE

The attention towards innovative steels at limited cost increased significantly in the last years. The research focused mainly in the development of new high strength steels where a combination of elevated mechanical properties, good formability and weldability is required and of duplex stainless steels if high corrosion resistance and mechanical properties are demanded. The possibility to design new light components thanks to the higher strength of such steels, the substitution of expensive ...

Baldo, Silvia

2011-01-01

279

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

280

Corrosion protection by means of selective pre-oxidation. Final report. Korrosionsschutz durch gezielte Voroxidation. Abschlussbericht  

Energy Technology Data Exchange (ETDEWEB)

The preoxidation and corrosion tests were carried out on the steels and test alloys of the types AISI 310 and 309 as well as on the alloy 800 H. Test results show that the layers which were purposefully applied to the steels of the type AISI 310 protect the metal underneath for a residence period of up to 7000 h. The oxide layers of the alloy 800 H showed only a limited protective effect. (MM).

Frommann, A.

1988-04-01

281

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)

282

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

283

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.)

284

Corrosion protective coating for metallic materials  

Science.gov (United States)

Corrosion protective coatings for metallic materials, particularly aluminum and aluminum alloys, produced with simple, low-cost equipment and materials other than toxic metals or metal salts, or metal cyanides is disclosed. The metallic material is cleaned, degreased, and deoxidized, the surface is converted to a substantially alkaline condition, and the surface is chemically sealed with inorganic metal compounds. 1 fig.

Buchheit, R.G.; Martinez, M.A.

1998-05-26

285

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

286

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

287

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. J-13 well water is representative of water which has percolated through the tuff horizon where the repository would be located. Tests were conducted in air-sparged J-13 water to attain stronger oxidizing conditions. 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 refs., 7 tabs

288

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)

289

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

290

Corrosion Behavior of Mild Carbon Steel in Ethanolic Solutions  

Science.gov (United States)

Electrochemical evaluation of ASTM A36 steel was performed in ethanolic solutions containing small concentrations of water ranging from 0 to 10 vol.%. Electrochemical techniques such as open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization were utilized to analyze corrosion parameters. A fixed concentration of chloride, as per the ASTM specification for fuel grade ethanol, was added to increase the conductivity of the solutions. The effects of water and oxygen on the corrosion behavior of steel in these solutions have been discussed. Pitting corrosion of the steel specimens in these solutions was evaluated using scanning electron microscopy (SEM) and pitting analysis. This investigation was performed to establish a baseline for the microbiologically influenced corrosion (MIC) of steel in ethanolic solutions.

Bhola, Shaily M.; Bhola, Rahul; Jain, Luke; Mishra, Brajendra; Olson, David L.

2011-04-01

291

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

292

Corrosion resistance of high-manganese austenitic steels  

Directory of Open Access Journals (Sweden)

Full Text Available 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 percentage weight loss was calculated. The metallographic investigations of corrosion damages included light and scanning electron microscope observations 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 ? and ?’ martensite plates in an austenitic matrix were observed. According to the results of the immersion tests it was found that the examined steels exhibit a comparable corrosion resistance. They show very poor corrosion resistance in H2SO4 solution and low corrosion resistance in NaCl medium. The weight loss in chloride solution is much lower, what is explained by different corrosion mechanisms. In both the solutions, the intensive general corrosion and corrosion pitting were observed. In acidic medium they are created in a way of hydrogen depolarization and in NaCl in the way of oxygen depolarization.Research limitations/implications: To investigate in more detail the corrosion behaviour of high-manganese austenitic steels, the investigations should include polarization tests and an analysis of corrosion products.Practical implications: The obtained results can be used to search for the appropriate way of improving the corrosion resistance of high-manganese steels with a single-phase austenitic structure as well as the austenite structure containing ? and ?’ martensite.Originality/value: The corrosion resistance of two types of advanced high-strength high-manganese austenitic steels with different initial structures was compared in acidic and chloride solutions.

A. Grajcar

2010-02-01

293

Optimal Piling Network Corrosion Protection System for Al-Zubair Harbor  

OpenAIRE

Cathodic protection is an effective electrochemical technique for preventing corrosion of metallic structures, for large structures like piles network impressed current cathodic protection (ICCP) system is usually preferred. The main aim of this study is to obtain the optimum protection potential that would provide a full cathodic protection for steel piles net-work immersed in sea water at Al-Zubair harbor. The effect of one immeasurable factor (path of anode (?1)) an...

Hafiz, Mohammed H.; Hamdan, Wisam K.; Ruaa Kaream Salman

2012-01-01

294

Corrosion protection for silver reflectors  

Science.gov (United States)

A method of protecting silver reflectors from damage caused by contact with gaseous substances which are often present in the atmosphere and a silver reflector which is so protected. The inventive method comprises at least partially coating a reflector with a metal oxide such as aluminum oxide to a thickness of 15 .ANG. or less.

Arendt, Paul N. (Los Alamos, NM); Scott, Marion L. (Los Alamos, NM)

1991-12-31

295

Hardfaced welded protective coatings for corrosion and wear stresses  

International Nuclear Information System (INIS)

As a rule, materials which resist even extremely high corrosion and wear stresses, are very expensive and/or difficult to work. For this reason many efforts are made to avoid massive types of construction, if possible, and only to provide the stressed surface with a suitable protective coating. An economically favourable alternative, which is particularly used for thick-walled components, is hardfacing welding. With this it is possible to use coated basic materials, eg: unalloyed steels as the sources of mechanical strength, and to coat the surface with different hardfacing welding processes according to the stresses on it. (orig.)

296

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

297

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

298

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

International Nuclear Information System (INIS)

The use of thermal spray stainless steel coatings for protection of low alloyed steels against different types of corrosion is limited due to high porosity levels and oxide inclusions. In this paper electrochemical methods like corrosion potential monitoring and cyclic voltammetry are reported to monitor the corrosion resistance of thermal spray coatings. The studied stainless steel AISI 316 coatings are deposited by arc spraying, plasma spraying or high velocity oxygen fuel (HVOF) spraying. The electrochemical tests are performed in a 0.5 M H2SO4 solution. It is found that none of the tested coatings had an electrochemical response equal to that of stainless steel alloy AISI 316. The results indicate that the HVOF coating has the highest corrosion resistance and the corrosion resistance of arc spray coatings can be improved by spraying in an inert argon atmosphere. The electrochemical response of the studied arc spray coatings is independent of substrate type (including the case of no substrate), indicating that the underlying alloy does not contribute to the corrosion process and only the coating itself is attacked. The HVOF coatings age rapidly in a 0.5 M H2SO4 solution. It is proposed that this is due to pore opening and pore widening. (orig.)

299

Radiation effects on noble steel corrosion in nitric acid  

International Nuclear Information System (INIS)

The highgrade steel 1.4301 with 17% Cr and 8.5% Ni was preferably analyzed: the time-invariant rate of corrosion depends on the nitric acid concentration (?[HNO3]5/3) and the temperature (activation energy 63.1 kJ). Foreign salts (Ce4+, chromate, fluoride, J-, JO3-, JO4-) increase the corrosion rate only if the ions have either an oxidizing or complexing effect. Iodate ions decrease the corrosion rate. With ?- or ? radiation, a significant increase of the corrosion rate was not noticed in any case after eliminating experimental difficulties. The higher corrosion rate caused by oxidizing agents (Cr6+, Ce4+) is, however, decreased, since these compounds are also reduced by the reactive species occurring in water radiolysis. A mechanical damage of the passive layer of highgrade steel in the presence of nitric acid and foreign salts does not lead to an increased corrosion rate in subsequent total immersion tests. (orig./MM)

300

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 immer...

Viera Zatkalíková; Tatiana Liptáková

2011-01-01

301

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)

302

Novel Corrosion Inhibitor for Mild Steel in HCl  

OpenAIRE

Corrosion inhibitory effects of new synthesized compound namely 5,5'- ((1Z,1'Z)-(1,4-phenylenebis(methanylylidene))bis(azanylylidene))bis(1,3,4-thiadiazole-2-thiol) (PBB) on mild steel in 1.0 M HCl was investigated at different temperatures using open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). Results showed that PBB inhibited mild steel corrosion in acid solution and indicated that the inhibition efficiencies increased with t...

Al-amiery, Ahmed A.; Kadhum, Abdul Amir H.; Alobaidy, Abdul Hameed M.; Abu Bakar Mohamad; Pua Soh Hoon

2014-01-01

303

New high-strength nitrogen-bearing corrosion resistant steel  

International Nuclear Information System (INIS)

The alloying element effect (nitrogen, molybdenum, nickel, manganese, silicon, chromium) on structure and properties of a newly designed high strength low-magnetization steel grade NS-5T is studied. Mechanical and corrosion tests are carried out for both a base metal and welded joints. It is shown that steel NS-5T is promising as an elevated strength material for application in a wide temperature range (from cryogenic temperature up to 1000 deg C) and in corrosive environments

304

Experimental stress corrosion testing of austenitic chromium-nickel steel  

International Nuclear Information System (INIS)

Facility and method for stress corrosion testing of stainless steel used in heat exchangers of power plants have been developed. The method enables to perform accelerated tests in weakly concentrated media in high-pressure vessels. Experiments were conducted for specimens of 08Kh18N10T steel in NaCl solutions using anode polarization from external power source as accelerating factor of stress corrosion. The necessity of complete exclusion of chlorine ion from feed water of steam generators is noted

305

Corrosion resistance properties of sintered duplex stainless steel  

OpenAIRE

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 ...

Dobrzan?ski, L. A.; Brytan, Z.; Actis Grande, M.; Rosso, M.

2006-01-01

306

A review of steel corrosion by liquid lead and lead-bismuth  

Energy Technology Data Exchange (ETDEWEB)

Liquid metal technologies for liquid lead and lead-bismuth alloy are under wide investigation and development for advanced nuclear energy systems and waste transmutation systems. Material corrosion is one of the main issues studied a lot recently in the development of the liquid metal technology. This study reviews steel corrosion by liquid lead and lead-bismuth, including the corrosion inhibitors and the formation of the protective oxide layer. The available experimental data are analyzed by using a corrosion model in which the oxidation and scale removal are coupled. Based on the model, long-term behaviour of steels in liquid lead and lead-bismuth is predictable. This report provides information for the selection of structural materials for typical nuclear reactor coolant systems when selecting liquid lead or lead-bismuth as heat transfer media.

Zhang Jinsuo [Decision and Application Division, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States)], E-mail: jszhang@lanl.gov

2009-06-15

307

A review of steel corrosion by liquid lead and lead-bismuth  

International Nuclear Information System (INIS)

Liquid metal technologies for liquid lead and lead-bismuth alloy are under wide investigation and development for advanced nuclear energy systems and waste transmutation systems. Material corrosion is one of the main issues studied a lot recently in the development of the liquid metal technology. This study reviews steel corrosion by liquid lead and lead-bismuth, including the corrosion inhibitors and the formation of the protective oxide layer. The available experimental data are analyzed by using a corrosion model in which the oxidation and scale removal are coupled. Based on the model, long-term behaviour of steels in liquid lead and lead-bismuth is predictable. This report provides information for the selection of structural materials for typical nuclear reactor coolant systems when selecting liquid lead or lead-bismuth as heat transfer media.

308

Corrosion resistance of chromized 316L stainless steel for PEMFC bipolar plates  

Energy Technology Data Exchange (ETDEWEB)

Corrosion resistance of the chromized 316L stainless steel was studied in a proton exchange membrane fuel cell (PEMFC) operating condition. Cr-rich surface layer was formed by pack cementation technique and electrochemical properties of the chromized surface were examined by potentiodynamic and potentiostatic tests. Results showed that the Cr-rich layers underneath the free surface passivated the surface and protect the surface from corrosion in 0.5 M H{sub 2}SO{sub 4} solution at 80 C. However, the Cr-rich layers showed columnar grains with voids when the stainless steel was pack cemented for an extended period of time, resulting in drastic degradation of corrosion resistance. The optimum condition for the best corrosion resistance in the PEMFC operating condition was obtained without sacrificing the interfacial contact resistance. (author)

Cho, K.H.; Lee, W.G.; Lee, S.B.; Jang, H. [Department of Materials Science and Engineering, Korea University, 1, 5-ga, Anam-dong, Sungbuk-gu, Seoul 136-701 (Korea)

2008-04-01

309

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

310

Influence of sulphur content, sulphur distribution and deoxidation practice on the corrosion of steel in seawater  

International Nuclear Information System (INIS)

Seven steels, mainly differing by the sulphur content have been exposed for two years in the splash water-, alternate immersion-, and continuous immersion zones of the test stand Helgoland of the Verein Deutscher Eisenhuettenleute. High sulphur contents led in the splash water zone to a markedly higher corrosion attack. This is attributable to the formation of sulphate clusters, reducing the protective effect of formed rust layers. In addition, the sulphur content influences to a slight extent also the formation of the surface layers in the alternate immersion zone. In the continuous immersion zone, there is no evidence of any influence of the sulphur on corrosion. The deoxidation practice and the distribution of the sulphur had no bearing on the corrosion rates. A localy increased corrosion attack, being in a causal connection with the sulphides in the steel, was not observed. (orig./RW)

311

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in english 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.

312

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.)

313

Corrosion resistance of Cr18Ni10Ti steel  

International Nuclear Information System (INIS)

The results are given of an investigation of the pitting and crevice corrosion and of the corrosion cracking of the title steel. Pitting corrosion was observed for steam generator tubes. Growth was found of open pits in the active state and of pits with an oxide layer. Deposits which formed on the heat exchange surfaces of the components during operation play an important part in the local corrosion. The initiation and growth of pits during the steam generator operation is strongly affected by the presence of chlorides and copper released by corrosion from the brass condenser tubes. Another kind of corrosion consists in the sub-surface damage of tubes, of the sealing welded joint and of the tube plate on the floating exchanger lid side. Mechanical stress of the thick-walled steam generator components along with the corrosive effect of the medium brings about failure of the structural material by corrosion cracking. Tube plates are the sites where corrosion cracking is most frequently initiated and developed. To ensure corrosion resistance of the steel, the amounts of aggressive components and corrosion products in water must be decreased, local mechanical stresses must be reduced, the surface quality must be improved and the presence of sulfide inclusions in the matrix must be restricted. (M.D.)

314

Influence of Paint on Steel Corrosion for Marine Applications  

OpenAIRE

The majority of naval ships are constructed of mild steel. Corrosion is a major concern in a maritime environment. This particular type of material degradation has recently received more attention by the marine industry. The present work aims to investigate the effect of recent coatings used in marine ship surfaces for preventing corrosion. Experiments were performed according ...

Abdou Abdel-Samad; Yaser Soud; Zaki, M.

2014-01-01

315

Corrosion behaviour and biocorrosion of galvanized steel water distribution systems.  

Science.gov (United States)

Galvanized steel tubes are a popular mean for water distribution systems but suffer from corrosion despite their zinc or zinc alloy coatings. First, the quality of hot-dip galvanized (HDG) coatings was studied. Their microstructure, defects, and common types of corrosion were observed. It was shown that many manufactured tubes do not reach European standard (NBN EN 10240), which is the cause of several corrosion problems. The average thickness of zinc layer was found at 41?m against 55?m prescribed by the European standard. However, lack of quality, together with the usual corrosion types known for HDG steel tubes was not sufficient to explain the high corrosion rate (reaching 20?m per year versus 10?m/y for common corrosion types). Electrochemical tests were also performed to understand the corrosion behaviours occurring in galvanized steel tubes. Results have shown that the limiting step was oxygen diffusion, favouring the growth of anaerobic bacteria in steel tubes. EDS analysis was carried out on corroded coatings and has shown the presence of sulphur inside deposits, suggesting the likely bacterial activity. Therefore biocorrosion effects have been investigated. Actually sulphate reducing bacteria (SRB) can reduce sulphate contained in water to hydrogen sulphide (H2S), causing the formation of metal sulphides. Although microbial corrosion is well-known in sea water, it is less investigated in supply water. Thus, an experimental water main was kept in operation for 6months. SRB were detected by BART tests in the test water main. PMID:24503139

Delaunois, F; Tosar, F; Vitry, V

2014-06-01

316

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

317

Effect of hydrogenase on the corrosion of mild steel  

OpenAIRE

Losses due to corrosion are evaluated at 4% of the GDP of industrialised countries and biocorrosion may be responsible for 10% of these costs [1]. Whereas the general mechanism of anaerobic corrosion, involving iron sulphur deposits, seems now well agreed, the detailed mechanism is still unclear and the implication of hydrogenase is very controversial. The influence of a [Fe] hydrogenase from C. acetobutylicum on mild steel corrosion was studied using a galvanic cell and measuring the current...

Mehanna, Maha; Basse?guy, Re?gine; De?lia, Marie-line; Bergel, Alain

2007-01-01

318

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-11-25

319

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

320

Stress corrosion cracking protection device  

International Nuclear Information System (INIS)

Purpose: To reduce dissolved oxygen at a reduced cost and simply thereby prevent stress corrosion cracking. Constitution: Taking notice of the fact that dissolved oxygen concentration is reduced in reactor water in contact with organic materials irradiated with radioactive rays such as ?-rays, organic materials such as polyethylenes are disposed to the inside of pipeways in reactor clean-up systems and radioactive rays are irradiated to them. Thus, reactor water can be brought into contact with organic materials, by which dissolved oxygen is caught by organic materials under the action of the radioactive rays to reduce the dissolved oxygen concentration. Further, if the organic materials are disposed to the inside of the pipeways connecting the heat exchanger and the desalter of the clean-up system, since the temperature of the reactor water is relatively low and the flow rate is not so high in this portion, dissolved oxygen can be removed stably and efficiently. (Kawakami, Y.)

321

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

322

Corrosion protection and finishing of automobiles  

International Nuclear Information System (INIS)

finishing of automobiles is an important aspect. There have been considerable reductions of weight in automobiles by the use of composites components replacing heavy metallic components. Fenders previously based on metal have been replaced with plastic and painted with the same colour shade as of the metallic body, this has eps for proper adhesion of the paints on the plastic fender to avoid chipping off the paint form it. This paper discusses the necessary processes required for finishing of an automobile along with the corrosion protection measures. Automobiles contains a variety of engineering materials, engine main body fuel tanks connecting rods heat radiators and other mechanical parts are made from different types of engineering alloys having varying chemical compositions. Other parts like dashboard, front panel and other are made from composites. The main body made from cold roll ed steel having various contours 'c' it due to the different designs is the potential site for corrosion attack, The main body is exposed to the hostile environment through out its life period. An automobile is given a particular finish with a view to counter the hostile environments as they are not limited for plying in a limiting conditions and are taken to different weather conditions in one day thus facing severe stresses and strain. Thus it is essential that an automobile before rolling 'out of the assembly line should properly corrosion resistant and aesthetically pleasant also.resistant and aesthetically pleasant also. Finishing for automobiles being very specialized, the main requirement being maximum durability with minimum numbers of coats baked, at the fastest possible schedule. High gloss and range of good eye catching colours being important to increase sales appeal. In the near past the car finishes were based on alkyd-amino resins baking materials and force drying lacquers, which have excellent appearance originally and maintain it on aging. The finishing system for the synthetic baking type may consist of one primer coat and a double finish coat. The two finishing coats are applied one immediately after the other, and both are baked simultaneously. An alternate system is to apply a red iron oxide epoxy primer followed by a gray epoxy primer and to bake the two coats at 200 degree C for about 35 minutes. The dry film thickness is about is about 1.5 mils. This coating is wet sanded, washed, and dried then top-coated with a double (wet-on-wet) coat of alkyd-amino resin enamel. The enamel is baked at 120 degree C for about 35 minutes. The lacquer system consists of one prime coat followed by several coats of lacquer finish. Number of coats depending on the price range of the car. All the efforts are made to make the metal surface as smooth as possible and free from rough places due to spot wielding and filing. This means a minimum of sanding on the primer, thus saving in labour cost but also makes possible less pigment in the primer resulting in better hold-out of the finish. However, the primer must be hard enough to sand easily, because rubbery primers tare slow sanding and tend to show scratch marks from the sand paper. All metal surfaces are given a passivating treatment before application of the primer. (author)

323

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

Energy Technology Data Exchange (ETDEWEB)

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 studied coatings suffered crevice corrosion in chloride solution. Despite high Mo-alloying the best coatings reached only the corrosion resistance of AISI 316.

Siitonen, P.; Konos, T.; Kettunen, P.O. [Tampere Univ. of Technology (Finland)

1994-12-31

324

Corrosion protection and the A-1 nuclear power plant  

International Nuclear Information System (INIS)

A high pressure water loop permitting water circulation at a rate of up to 3 m/s at a pressure of 6.5 MPa and temperature of up to 100 degC was linked to the WWR-S reactor. It is designed for corrosion protection research of the A-1 reactor heavy-water vessel made from aluminium alloy SAV-1 containing magnesium and silicon. As for corrosion, the loop parameters correspond to the conditions of the weakest points in the A-1 reactor core, the so-called caisson tubes, i.e., the channels for gas-cooled fuel elements. The corrosion process was studied by gravimetric evaluation of weight losses, by the microscopic inspection of the surfaces of aluminium alloy specimens and by the remote continuous polarizing resistance method. It was found that apart from the presence of radiation, the main cause of aluminium corrosion in CO2-saturated water flowing at a pressure of 6.5 MPa was the acidic reaction of the water medium. The application of phosphate ions reduced the corrosion rate down to 0.04 to 0.08 mm/h. The optimal concentration was 30 mg PO3-/l for a directly exposed medium and 1 to 2 mg PO3-/l for an unexposed medium. The inhibitory effect of phosphoric acid was enhanced by the addition of potassium ions at a concentration of 100 to 200 mg K+/l. The use of inhibitors negligibly affected reactivity and had no effect on heavy water radiolysis. In addition, they showed a favourable effect on stainless steel st a favourable effect on stainless steel structural materials. (Z.M.)

325

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.

326

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

Science.gov (United States)

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.

Sahri, M. I.; Othman, N. K.; Samsu, Z.; Daud, A. R.

2014-09-01

327

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

328

Heat transfer corrosion of stainless steel in nitric acid  

International Nuclear Information System (INIS)

Full text of publication follows: In nuclear reprocessing plants, interest is focused on the behaviour of stainless steels in nitric acid solutions, the principal heated process vessels being spent-fuel dissolvers and evaporators. The corrosion of stainless steels by nitric acid is known to be complex, being affected by a host of metallurgical and environmental factors. Amongst the latter, temperature exerts a strong effect, the corrosion rate typically doubling for a temperature increase of 7-10 C depending on the exact liquor composition. The type of corrosion which occurs is intergranular whereby grain boundaries between individual stainless steel crystals are subject to attack. This is due to differing local concentrations of alloying metals and interstitial contaminants at the grain boundaries and eventually causes entire crystals to detach from the bulk steel. Less well understood is what, if any, effect a temperature gradient between the liquor and the stainless steel vessel exerts on this corrosion mechanism and therefore the corrosion rate of dissolvers and evaporators exposed to these conditions. Possible effects include changing mass transport mechanisms to the surface of the steel, a temperature gradient could also influence what corrosion products are formed at the surface which in turn has a considerable affect on the passivity of the steel. This project is concerned with the corrosion rate of stainless steel heat transfer surfaces contacted by nitric act transfer surfaces contacted by nitric acid solutions and comparing this with corrosion rate data obtained isothermally at equivalent effective surface temperatures. This comparison will confirm or deny whether additional corrosion effects occur. A wide range of heat transfer conditions will be tested using a variety of nitric acid liquors. Using weight loss and electrochemical techniques it is possible to deduce the corrosion rate as a function of time. Various microscopy techniques are also employed to provide a qualitative understanding of the corrosion mechanisms involved. This has been achieved under isothermal conditions. It is far more challenging to design and construct experimental apparatus which allow a comparison with heat transfer surfaces. Such a novel test rig was completed and commissioned in January 2009. Due to the timescales of the procedures involved and the complexity and originality of the apparatus a comparison of corrosion rates is not imminent

329

Interaction of corrosion inhibitors with corroded steel surface  

Energy Technology Data Exchange (ETDEWEB)

Effects of corrosion inhibitors on corrosion products of iron or steel in aqueous solutions are reviewed. Several organic and inorganic compounds seem to have sufficient inhibition effects on rusted surfaces, but details such as the mechanism or influence of solution properties are not known. Although the complexity of the chemistry of corrosion products makes it difficult to study the interaction between inhibitors and rusted steel surface, there is a need for a better understanding of the interaction to meet with success in a practical use of inhibitors.

Kowata, Kenji; Takahashi, Kuniyuki [Kurita Water Industries Ltd., Atsugi, Kanagawa (Japan). Kurita Central Labs.

1996-12-01

330

Corrosion protection for silver reflectors  

International Nuclear Information System (INIS)

This patent describes a method of protecting a silver reflector from damage caused by contact with gaseous substances. It comprises: at least partially coating the reflector to a thickness of 15 Angstrom or less with a substance selected from a group containing aluminum oxide, magnesium oxide, titanium dioxide, silicon dioxide, yttrium oxide, hafnium oxide, zirconium oxide, and praseodymium oxide

331

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 three types of liquid breeders (i.e. Li, Pb-17Li and Flinak) were performed at 600 oC. The influence of the different experimental parameters, such as a flowing condition, an exposure time and a geometric condition, on the corrosion behavior was investigated. The present study focused on the evaluation of the weight loss of the corroded specimen by the corrosion model based on mass transfer. The dissolution of the metal elements from the steel was accelerated by the fluids. An erosion-corrosion of the steel was caused by the peeling off of the corroded steel surface in the flowing liquid breeders.

332

Corrosion behaviour in alkaline medium of zinc phosphate coated steel obtained by cathodic electrochemical treatment  

International Nuclear Information System (INIS)

The present work evaluated the ability of zinc phosphate coating, obtained by cathodic electrochemical treatment, to protect mild steel rebar against the localized attack generated by chloride ions in alkaline medium. The corrosion behaviour of coated steel was assessed by open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. The chemical composition and the morphology of the coated surfaces were evaluated by X-ray diffraction and scanning electron microscopy. Cathodically phosphated mild steel rebar have been studied in alkaline solution with and without chloride simulating the concrete pore solution. For these conditions, the results showed that the slow dissolution of the coating generates the formation of calcium hydroxyzincate (Ca(Zn(OH)3)2.2H2O). After a long immersion time in alkaline solution with and without Cl-, the coating is dense and provides an effective corrosion resistance compared to mild steel rebar.

333

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

334

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

335

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

336

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.

337

Corrosion of steel in simulated nuclear waste solutions  

International Nuclear Information System (INIS)

Processing of inhibited nuclear waste to forms for long-term storage will cause waste tank environments to have dynamic conditions. During processing compositional changes in the waste may produce a corrosive environment for the plain carbon steel tanks. Large concentrations of nitrates which corrode steel are contained in the waste. Nitrite and hydroxides are added to inhibit any corrosion. Concentration changes of nitrate and nitrite were investigated to identify corrosion regimes that may occur during processing. Corrosion testing was performed with cyclic potentiodynamic polarization and linear polarization resistance. Test samples were plain carbon steel which was similar to the material of construction of the waste tanks. The corrosion morphology of test samples was investigated by visual evaluation and scanning electron microscopy. Qualitative chemical analysis was also performed using energy dispersive spectroscopy. The corrosion mechanism changed as a function of the nitrate concentration. As the nitrate concentration was increased the steel transitioned from a passive state to general attack, and finally pitting and crevice corrosion. The nitrate anion appeared to destabilize the surface oxide. Nitrite countered the oxide breakdown, although the exact mechanism was not determined

338

Corrosion of steel H piles in decomposed granite  

Energy Technology Data Exchange (ETDEWEB)

To study the corrosion of steel H piles in a completely decomposed granite, piles were exposed by excavation 22 years after their installation. The thickness of the pile sections was measured. The average corrosion rate of the steel piles was estimated to be 0.011 mm/year, and the maximum corrosion rate was estimated to be 0.015--0.018 mm/year. The rates are low. The results confirm the conclusions derived from tests done in places with temperate climate that steel piles installed in undisturbed, native soils undergo little corrosion. Thus, such conclusions are also applicable to the completely decomposed granite in a place like Singapore with high year-round temperatures ranging from 25 to 35 C.

Wong, I.H. [Mitic Associates, Cashew Heights (Singapore); Law, K.H. [Land Transportation Authority, Singapore (Singapore)

1999-06-01

339

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.

340

Corrosion of carbon steel in brine: Mg/sup ++/ effect  

International Nuclear Information System (INIS)

Carbon steels has potential as a candidate material for containment of high level nuclear waste in permanent repositories in rock salt. In addition to large amounts of NaCl, rock salt contains significant amounts of other chlorides, especially Magnesium chloride. The increase in corrosion rate of carbon steel in brines containing Mg/sup 2+/ ions has been reported previously. The objective of the present investigation was to identify the mechanism which leads to the observed high corrosion rates of carbon steel in Mg/sup 2+/ containing brines

341

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

342

76 FR 3613 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Final Results of...  

Science.gov (United States)

...Trade Administration [C-580-818] Corrosion-Resistant Carbon Steel Flat Products...countervailing duty (CVD) order on corrosion-resistant carbon steel flat products...2008, through December 31, 2008. See Corrosion-Resistant Carbon Steel Flat...

2011-01-20

343

76 FR 54209 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Preliminary Results of...  

Science.gov (United States)

...Trade Administration [C-580-818] Corrosion-Resistant Carbon Steel Flat Products...countervailing duty (CVD) order on corrosion-resistant carbon steel flat products...with regard to Dongbu and POSCO. See Corrosion-Resistant Carbon Steel Flat...

2011-08-31

344

76 FR 77775 - Corrosion-Resistant Carbon Steel Flat Products from the Republic of Korea: Extension of Time...  

Science.gov (United States)

...Trade Administration [C-580-818] Corrosion-Resistant Carbon Steel Flat Products...review of the countervailing duty order on corrosion-resistant carbon steel flat products...2009, through December 31, 2009. See Corrosion-Resistant Carbon Steel Flat...

2011-12-14

345

77 FR 72827 - Corrosion-Resistant Carbon Steel Flat Products From Germany and the Republic of Korea: Final...  

Science.gov (United States)

...Administration [A-428-815 and A-580-816] Corrosion-Resistant Carbon Steel Flat Products...duty (``AD'') orders on certain corrosion- resistant carbon steel flat products...1\\ Corrosion-Resistant Carbon Steel Flat...

2012-12-06

346

77 FR 13093 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Final Results of...  

Science.gov (United States)

...Trade Administration [C-580-818] Corrosion-Resistant Carbon Steel Flat Products...countervailing duty (``CVD'') order on corrosion-resistant carbon steel flat products...1\\ See Corrosion-Resistant Carbon Steel Flat...

2012-03-05

347

Corrosion behavior of al-alloying high Cr-ODS steels in lead-bismuth eutectic  

International Nuclear Information System (INIS)

Full text of publication follows: Development of high corrosion resistant fuel cladding materials is very important for enhancement of the efficiency of a Lead-Bismuth Eutectic (LBE) cooled fusion reactor and a fast breeder reactor. Concerning an Oxide Dispersion Strengthened (ODS) steel, which is one of the promising candidate materials, recently, the authors' group has reported that Al alloying high Cr-ODS steels have much higher corrosion resistance in LBE than a 9Cr-ODS steel without Al. Addition of Al, however, may cause coarsening of ODS particles and decrease in high-temperature strength. Too much higher Cr content also has a problem of aging embrittlement. Therefore, it is needed to reveal the effect of Al and Cr on formation of protective scales on the material surface and find optimal amount of Al and Cr to balance corrosion resistance and high-temperature strength. In this study, the corrosion tests were performed for the ODS steels with various Al and Cr contents, from 0 wt% to 3.5 wt% and from 13.7 wt% to 17.3 wt%, respectively, in stagnant LBE containing 10-6 wt% and 10-8 wt% oxygen at temperature of 823 K and 923 K for 1000 h and 3000 h. Before and after the corrosion tests, the scanning electron microscopy observation and energy-dispersive X-ray spectroscopy analysis were done. While the ODS steel containing 16.0 wt% Cr and no Al suffered from dissolution attack just after 1000 h in all the cases, the ODS steels containing Al showe cases, the ODS steels containing Al showed relatively good corrosion resistance even after 3000 h. For example, in the case of the ODS steel alloyed with 17.3 wt% Cr and 3.5 wt% Al exposed in LBE with 10-6 wt% oxygen at 923 K for 3000 h, the whole surface was protected by around 1 mm-thick alumina scale, and there is no oxygen diffusion zone. Among the ODS steels containing the same level of Al, there is tendency that less internal oxidation is formed in higher Cr-ODS steels. In the presentation, the effect of Cr will be discussed further in comparison with the 12Cr steel. (authors)

348

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

349

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

350

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

351

Corrosion of carbon steel nuclear waste containers in marine sediment  

International Nuclear Information System (INIS)

The report describes a study of the corrosion of carbon steel nuclear waste containers in deep ocean sediments, which had the objective of estimating the metal allowance needed to ensure that the containers were not breached by corrosion for 1000 years. It was concluded that under such disposal conditions carbon steel would not be subject to localised corrosion or hydrogen embrittlement, and therefore the study concentrated on evaluating the rate of general attack. This was carried out by developing a mechanistically based mathematical model which was formulated on the conservative assumption that the corrosion would be under activation control, and would not be impeded by the formation of corrosion product layers. This model predicted that an allowance of 33 mm would be required for a 1000 year life. (author)

352

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

353

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

354

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

355

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

356

Results of steel corrosion tests in flowing liquid Pb/Bi at 420-600 deg. C after 2000 h  

International Nuclear Information System (INIS)

Corrosion tests were carried out on austenitic AISI 316L and 1.4970 steel and on MANET steel up to 2000 h of exposure to flowing (up to 2 m/s) Pb/Bi. The concentration of oxygen in the liquid alloy was controlled at 10-6 wt%. Specimens consisted of tube and rod sections in original state and after alloying of Al into the surface. After 2000 h of exposure at 420 and 550 deg. C the specimen surfaces were covered with an intact oxide layer which provided a good protection against corrosion attack of the liquid Pb/Bi alloy. At the same time corrosion attack at 600 deg. C was severe at the original AISI 316L steel specimens. The alloyed specimens containing FeAl on the surface of the alloyed layer still maintained an intact oxide layer with good corrosion protection up to 600 deg. C. (author)

357

Corrosion behaviour of AISI 304 stainless steel with Cu coatings in H2SO4  

International Nuclear Information System (INIS)

The work addresses the influence of cementation and electrodeposition of copper coatings on the corrosion resistance of AISI 304 stainless steel immersed in 30 wt.% H2SO4 at temperatures of 25 and 50 deg. C. Corrosion process was evaluated by gravimetric tests, DC measurements and electrochemical impedance spectroscopy (EIS). The specimen surfaces were analysed by scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. The corrosion performance of AISI 304 stainless steel in sulphuric acid solution was greatly improved by copper coatings. The amount of copper deposited by the cementation process was sufficient to protect the stainless steel of corrosion. A greater amount of copper obtained by electrodeposition treatments does not supply further improvement in the corrosion behaviour. The improved corrosion resistance is related to copper dissolution at the initial stages of immersion tests and the presence of Cu2+ in the solution, which makes the medium more oxidizing, increasing the stability of the passive layer. In addition, the presence of copper at the surface reduces the overpotential of cathodic reaction, enabling the transition from an active region to the passive one

358

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

OpenAIRE

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 ess...

Mehanna, Maha; Basse?guy, Re?gine; De?lia, Marie-line; Bergel, Alain

2009-01-01

359

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)

360

Corrosion inhibition of mild steel by amphoteric surfactants  

Energy Technology Data Exchange (ETDEWEB)

The corrosion inhibition of mild steel, in 3% NaCl solution of pH3, by amphoteric surfactants was evaluated in absence and in presence of 600 and 1200 mg H{sub 2}S/I and at temperatures of 25, 40 and 65 C. The presence of surfactants in the aqueous solution affected both the cathodic and anodic polarization areas, the corrosion potential. E{sub corr}, shifted to more positive values and i{sub corr}, decreased with the increase of surfactants concentrations. These surfactants have a good ability to form protective layer on the metal surface even in the presence of small concentrations of the surfactant. This was attributed to the amphoteric properties of the surfactants which contain both anionic and cationic moiety in the same molecule and also to the pressure of Cl{sup -} ions in the aqueous solution. The inhibiting efficiency of the surfactants increased with the increase of the length of alkyl groups (R) in the surfactant. The value of P.I. increased to some extent in synergistic effect. (orig.) 24 refs.

Barakat, Y.F. [Tabbin Inst. for Metallurgical Studies, Cairo (Egypt); Hassan, A.M. [General Co. for Petroleum, Cairo (Egypt); Baraka, A.M. [Cairo Univ., Giza (Egypt). Dept. of Chemistry

1999-07-01

361

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

362

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

Energy Technology Data Exchange (ETDEWEB)

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{sup -3} mmpy in the test condition of 500 ppm as NO{sub 2}{sup -}, 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.

Moon, Jeon Soo; Lee, Jae Kun [Green Growth Laboratory, Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

2010-06-15

363

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

364

Correlation between composition of passive layer and corrosion behavior of high Si-containing austenitic stainless steels in nitric acid  

International Nuclear Information System (INIS)

Austenitic stainless steels with 18% Cr have a good corrosion behavior in pure nitric acid. However, when oxidizing power of the solution increases, this kind of stainless steels faces a severe intergranular corrosion. Adding a sufficiently high concentration of silicon to the steel avoids this type of corrosion: in oxidizing solutions, those stainless steels exhibit generalized corrosion but their dissolution rate is higher than the one of stainless steels without silicon. To find out the role of silicon on such effects, the corrosion behavior of two different stainless steels with equivalent chromium content but with different silicon content (304L steel and Uranus S1N) has been studied in concentrated nitric acid solutions. Correlations have been evidenced between the passive layer composition investigated by XPS analysis and the corrosion behavior characterized by electrochemical techniques. The presence of silicon in the steel changes neither the oxidation state of chromium or iron, nor the ratio between iron and chromium in the passive layer. Silicon is present in the passive layer in an important content (35 at.%) and thus decreases the chromium content of the passive layer (80 and 50 at.% respectively for 304L steel and Uranus S1N after nitric passivation). Uranus S1N exhibits a less protective passive layer and so its generalized corrosion rate is higher than the one of 304L steel. A selective deposition of platinoids highlights differences of polarization di highlights differences of polarization distribution on the surface between the grain boundaries and grain faces for theses steels. For Uranus S1N, the similar electrochemical behavior of grain boundaries and faces might be connected with the homogeneous silicon distribution

365

Acid electrolyte fuel cell method having improved carbon corrosion protection  

International Nuclear Information System (INIS)

Carbon containing members susceptible to corrosion in an acid electrolyte fuel cell are protected against such corrosion through the practice of supplying carbon dioxide gas to the fuel cell regions adjacent these members

366

Corrosivity of paper mill effluent and corrosion performance of stainless steel.  

Science.gov (United States)

Present study relates to the corrosivity of paper mill effluent and corrosion performance of stainless steel (SS) as a construction material for the effluent treatment plant (ETP). Accordingly, immersion test and electrochemical polarization tests were performed on SS 304?L, 316?L and duplex 2205 in paper mill effluent and synthetic effluent. This paper presents electrochemical polarization measurements, performed for the first time to the best of the authors' information, to see the influence of chlorophenols on the corrosivity of effluents. The corrosivity of the effluent was observed to increase with the decrease in pH and increase in Cl(-) content while the addition of [Formula: see text] tends to inhibit corrosion. Mill effluent was found to be more corrosive as compared to synthetic effluent and has been attributed to the presence of various chlorophenols. Corrosion performance of SS was observed to govern by the presence of Cr, Mo and N contents. PMID:25188842

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

2015-03-01

367

Corrosion and erosion-corrosion behaviors of carbon steel in naphthenic acid media  

Energy Technology Data Exchange (ETDEWEB)

The naphthenic acid corrosion (NAC) and erosion-corrosion (NAEC) behaviors of carbon steel were investigated detailedly in laboratory. The resistance to NAEC of pack-aluminized carbon steel and carbon steel coated by high velocity oxygen-fuel (HVOF) thermal-sprayed AISI 316L stainless steel, was also investigated in both laboratory and an oil refinery. It was found that the control-step of NAC was primarily dependent on the temperature. The NAC rate of carbon steel increased markedly with the increase of the total acid number and temperature, which may be attributed to the enhanced absorption and active reaction of naphthenic acid molecules on the metal surface. Increasing the velocity of flow seriously aggravated NAEC, especially in the high temperature range. The reasons were closely associated with the enhanced mass transfer and the accelerated active reaction as well as the rapid spallation of corrosion products from the metal surface. Both the aluminized carbon steel and the carbon steel covered by HVOF coating showed better resistance against NAEC compared to the carbon steel due to higher microhardness and corrosion resistance of their surface-layers. The HVOF coating is hopeful to be applied for NAEC prevention of the components in oil refineries in view of present experimental results. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

Wu, X.Q.; Jing, H.M.; Zheng, Y.G.; Yao, Z.M.; Ke, W. [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, South District, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016 (China)

2002-11-01

368

Corrosion and erosion-corrosion behaviors of carbon steel in naphthenic acid media  

International Nuclear Information System (INIS)

The naphthenic acid corrosion (NAC) and erosion-corrosion (NAEC) behaviors of carbon steel were investigated detailedly in laboratory. The resistance to NAEC of pack-aluminized carbon steel and carbon steel coated by high velocity oxygen-fuel (HVOF) thermal-sprayed AISI 316L stainless steel, was also investigated in both laboratory and an oil refinery. It was found that the control-step of NAC was primarily dependent on the temperature. The NAC rate of carbon steel increased markedly with the increase of the total acid number and temperature, which may be attributed to the enhanced absorption and active reaction of naphthenic acid molecules on the metal surface. Increasing the velocity of flow seriously aggravated NAEC, especially in the high temperature range. The reasons were closely associated with the enhanced mass transfer and the accelerated active reaction as well as the rapid spallation of corrosion products from the metal surface. Both the aluminized carbon steel and the carbon steel covered by HVOF coating showed better resistance against NAEC compared to the carbon steel due to higher microhardness and corrosion resistance of their surface-layers. The HVOF coating is hopeful to be applied for NAEC prevention of the components in oil refineries in view of present experimental results. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

369

Inhibiting mild steel corrosion from sulfate-reducing and iron-oxidizing bacteria using gramicidin-S-producing biofilms.  

Science.gov (United States)

A gramicidin-S-producing Bacillus brevis 18-3 biofilm was shown to reduce corrosion rates of mild steel by inhibiting both the sulfate-reducing bacterium Desulfosporosinus orientis and the iron-oxidizing bacterium Leptothrix discophora SP-6. When L. discophora SP-6 was introduced along with D. orientis to a non-antimicrobial-producing biofilm control, Paenibacillus polymyxa ATCC 10401, a corrosive synergy was created and mild steel coupons underwent more severe corrosion than when only D. orientis was present, showing a 2.3-fold increase via electrochemical impedance spectroscopy (EIS) and a 1.8-fold difference via mass-loss measurements. However, when a gramicidin-S-producing, protective B. brevis 18-3 biofilm was established on mild steel, the metal coupons were protected against the simultaneous attack of D. orientis and L. discophora SP-6. EIS data showed that the protective B. brevis 18-3 biofilm decreased the corrosion rate about 20-fold compared with the non-gramicidin-producing P. polymyxa ATCC 10401 biofilm control. The mass loss for the protected mild steel coupons was also significantly lower than that for the unprotected ones (4-fold decrease). Scanning electron microscope images corroborated the corrosion inhibition by the gramicidin-S-producing B. brevis biofilm on mild steel by showing that the metal surface remained untarnished, i.e., the polishing grooves were still visible after exposure to the simultaneous attack of the sulfate-reducing bacterium and the iron-oxidizing bacterium. PMID:15278311

Zuo, Rongjun; Wood, Thomas K

2004-11-01

370

Intergranular stress corrosion sensitivity in stabilized stainless steels  

International Nuclear Information System (INIS)

Stabilized stainless steels are used in ASEA-ATOM BWR's in a number of forged and casted components, viz. valve housings. Samples of steels that are Ti-stabilized have been analyzed for carbon, and then CERT-tested for intergranular stress corrosion (IGSCC). The steels tested are Sandvik 8R30 and VEW A700. The medium was water with 8 ppm O2 and at 286 degreeC, and a feed conductivity of less than 0.1?Scm-1. The tests show that the zone near welds in these stabilized steels which in strongly oxidizing acids are sensitive to knife line attack, are also in BWR systems sensitive to IGSCC. This type of corrosion can be inhibited by minimizing the carbon content of the steels. (Aa)

371

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)

372

Microbiologically influenced corrosion of steels by thermophilic and mesophilic bacteria  

Energy Technology Data Exchange (ETDEWEB)

Bacterial influenced corrosion of AISI 316 stainless steels (SS) and ASTM A36 carbon steel by two strains of sulfate reducing bacteria (SRB) were analyzed. Thermophilic and mesophilic bacteria were isolated from the condensate fluid of ''Los Azufres'', a geothermal electric field located in the State of Michoacan at Central Mexico. Anaerobic corrosion tests were carried out for 15, 30 and 60 days in lactate-containing media at 50 C and 40 C. Scanning electron microscopy (SEM) was used to determine corrosion morphology. Pitting density was determined with an optical microscope. Corrosion potential, anodic potentiodynamic polarization curves and pH values were measured under anaerobic conditions. Results show that the microbial activity influenced the overall corrosion process, whereas, pitting corrosion and localized attack corrosion (LAC) were found. The anodic polarization curves show that passivation and activation processes should take place on the steel surface of the sample and pH decreases as the exposure time increases. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Alfaro-Cuevas-Villanueva, R.; Cortes-Martinez, R.; Galvan-Martinez, R.; Torres-Sanchez, R. [Universidad Michoacana de San Nicolas de Hidalgo, Instituto de Investigaciones Metalurgicas, Edificio ' ' U' ' , C.U. Apartado Postal 52-B, CP, 58000, Morelia, Michoacan (Mexico); Garcia-Diaz, J.J. [Instituto Tecnologico de Morelia, Centro de Graduados, Morelia, Michoacan (Mexico)

2006-07-15

373

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)

374

Ni-W coatings electrodeposited on carbon steel: Chemical composition, mechanical properties and corrosion resistance  

International Nuclear Information System (INIS)

Highlights: ? Hard, ductile and adherent nanostructured Ni-W coatings on carbon steel. ? New procedures for achieving deposits by current pulse techniques. ? Current pulse frequency was the dominant factor to define coating characteristics. ? Ni-W coatings protect the carbon steel from corrosion induced by sulphate anions. - Abstract: Hard, ductile and adherent nanostructured Ni-W coatings were electrodeposited on carbon steel from electrolyte solutions containing sodium tungstate, nickel sulfate and sodium citrate, using different current pulse programs. Current pulse frequency was the dominant factor to define chemical composition, grain size, thickness and hardness. According to the electrodeposition conditions the deposited coatings showed 15-30 at% W, the grain size ranged from 65 to 140 nm, and the hardness varied from 650 to 850 Hv. Tungsten carbide also present in the coating contributed to its hardness. The corrosion resistance of the Ni-W coated steel was tested by potentiodynamic polarization in a neutral medium containing sulphate ions. The Ni-W coating protected the carbon steel from localized corrosion induced by sulphate anions.

375

Ni-W coatings electrodeposited on carbon steel: Chemical composition, mechanical properties and corrosion resistance  

Energy Technology Data Exchange (ETDEWEB)

Highlights: > Hard, ductile and adherent nanostructured Ni-W coatings on carbon steel. > New procedures for achieving deposits by current pulse techniques. > Current pulse frequency was the dominant factor to define coating characteristics. > Ni-W coatings protect the carbon steel from corrosion induced by sulphate anions. - Abstract: Hard, ductile and adherent nanostructured Ni-W coatings were electrodeposited on carbon steel from electrolyte solutions containing sodium tungstate, nickel sulfate and sodium citrate, using different current pulse programs. Current pulse frequency was the dominant factor to define chemical composition, grain size, thickness and hardness. According to the electrodeposition conditions the deposited coatings showed 15-30 at% W, the grain size ranged from 65 to 140 nm, and the hardness varied from 650 to 850 Hv. Tungsten carbide also present in the coating contributed to its hardness. The corrosion resistance of the Ni-W coated steel was tested by potentiodynamic polarization in a neutral medium containing sulphate ions. The Ni-W coating protected the carbon steel from localized corrosion induced by sulphate anions.

Arganaraz, M.P. Quiroga; Ribotta, S.B. [INQUINOA-CONICET, Instituto de Quimica Fisica, Facultad de Bioquimica, Quimica y Farmacia, Universidad Nacional de Tucuman, Ayacucho 471, (4000) San Miguel de Tucuman (Argentina); Folquer, M.E., E-mail: mefolquer@fbqf.unt.edu.ar [INQUINOA-CONICET, Instituto de Quimica Fisica, Facultad de Bioquimica, Quimica y Farmacia, Universidad Nacional de Tucuman, Ayacucho 471, (4000) San Miguel de Tucuman (Argentina); Gassa, L.M.; Benitez, G.; Vela, M.E.; Salvarezza, R.C. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CONICET, Suc. 4, C.C. 16, (1900) La Plata (Argentina)

2011-07-01

376

Pitting corrosion detection in stainless steels using ultrasounds; Deteccion de la corrosion por picadura en aceros inoxidables empleando ultrasonidos  

Energy Technology Data Exchange (ETDEWEB)

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)

Rodriguez, C.; Biezma, M. V.

2014-04-01

377

Investigation of Corrosion and Cathodic Protection in Reinforced Concrete. I: Application of Electrochemical Techniques:  

OpenAIRE

The electrochemical behavior of steel reinforcement in conditions of corrosion and cathodic protection was studied, using electrochemical impedance spectroscopy (EIS) and compared to reference (noncorroding) conditions. Polarization resistance (PR) method and potentiodynamic polarization (PDP) were employed as well, in addition to ac 2 pin electrical resistance monitoring, thus deriving a comparison of the involved parameters, mainly polarization resistance and bulk electrical properties, obt...

Koleva, D. A.; Wit, J. H. W.; Breugel, K.; Lodhi, Z. F.; Westing, E.

2007-01-01

378

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

379

Flow accelerated corrosion of carbon steel piping in nuclear power plants  

International Nuclear Information System (INIS)

Flow accelerated corrosion (FAC) is a process whereby the normally protective oxide layer on carbon or low alloy steel dissolved into a stream of flowing water resulting in increasing the corrosion rate. Major influencing factors that affect the FAC are flow velocity, temperature, pH, dissolved oxygen concentration, and steel composition. The experimental study described in this paper was focused on evaluating the FAC behavior of carbon steel according to environment conditions. Feasibility tests for the mitigation method against the FAC were also carried out with controlling the water chemistry and with applying the magnetic field. A high temperature rotating cylinder electrode (HTRCE) and a water chemistry control system was developed to perform the electrochemical test in high temperature water environments. The main design concept of HTRCE is to assure stable operation of working electrode in a severe environment, to insulate electrode housing except working electrode surface against external fluid, and to extract corrosion parameter from the rotating cylinder to outside of the autoclave safely. The electrochemical corrosion potential (ECP) and current density were measured as a function of temperature and rotating speed using polarization monitoring. ECP values dropped at a rate of -1.51 mV/.deg. C above 150 .deg. C, which may be come from the formation of magnetite on the steel surface. With increasing rotation of the RCE, the ECP shifted upward in all temperature ranges. This shift may be attributed to the diffusion enhancement of the oxidizing agents in the rapidly flowing of fluid. From the velocity exponent of the cathodic half-cell current density on the steel surface, it was evident that a mass transfer process first dominated the corrosion reaction at 150 .deg. C, and then an activation process partly controlled the corrosion kinetics with increasing temperature. From the results of corrosion experiment at high temperature water, HTRCE has been proved as an effective device to evaluate the velocity sensitivity of corrosion reaction in high temperature water. An electrochemical analysis was performed to evaluate the effects of fluid flow and dissolved oxygen on the corrosion behavior of carbon steel and to correlate electrochemical aspect with the flow accelerated corrosion rate. In neutral pH water containing 2 ppb oxygen, the ECP and corrosion current density were increased with rotation of electrode. Corrosion current density showed similar tendency with a wall shear stress on the surface of electrode due to the fluid flow. The wall shear stress might cause a decrease in the mass transfer boundary layer thickness resulting in increase in the rate of the corrosion reaction due to faster diffusion of the soluble corrosion product into the bulk solution. When the oxygen concentration exceeds a threshold concentration, the cathodic current previously supplied by the hydrogen evolution reaction is substituted by an equivalent reaction due to oxygen reduction. Thus, the ECP increases up to the range of hematite which has a very low solubility and electric conductivity. The hematite formation would lead to inhibit flow accelerated corrosion. The effects of a magnetic field on the FAC behavior of a low alloy steel were evaluated to develop a method to mitigate against feeder wall thinning. A magnet-attached rotating cylinder electrode and piping steel covered with simulated oxide film were used in potentiodynamic test and erosion test to determine the magnetic effect on electrochemical and erosional aspect of the oxide layer, respectively. An Electrochemical corrosion reaction was active in the magnetic field because the local mass transfer rate was increased by the magnetohydrodynamic force generated by a coupling of the electric and magnetic field. However, the magnetic field effect decreased with increasing temperature and rotation velocity. Those might be come from the facts that the thickness of the diffusion layer decreased with rotating velocity and the diffusion constant increased with increasing temperatu

380

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

381

Carbon steel protection in G.S. (Girlder sulfide) plants. CITROSOLV process influence. Pt. 6  

International Nuclear Information System (INIS)

In order to protect carbon steel towers and piping of Girlder sulfide (G.S.) experimental heavy water plants against corrosion produced by the action of aqueous solutions of hydrogen sulfides, a method, previously published, was developed. Carbon steel, exposed to saturated aqueous solutions of hydrogen sulfide, forms iron sulfide scales. In oxygen free solutions evolution of corrosion follows the sequence: mackinawite ? cubic ferrous sulfide ? troilite ? pyrrotite ? pyrite. Scales formed by pyrrotite-pyrite or pyrite are the most protective layers (these are obtained at 130 deg C, 2 MPa, for periods of 14 days). CITROSOLV Process (Pfizer) is used to descaling and passivating stainless steel plant's components. This process must be used in mixed (carbon steel - stainless steel) circuits and may cause the formation of magnetite scales over the carbon steel. The influence of magnetite in the pyrrotite-pyrite scales formation is studied in this work. (Author)

382

Erosion-corrosion of carbon steel in simulated tailing slurries  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: {yields} Physical model for predicting corrosion-enhanced erosion is established on basis of irreversible thermodynamics. {yields} The model for erosion-enhanced corrosion is modified to consider the non-uniform distribution of anodic dissolution over target surface. {yields} The models are validated by the in-situ microhardness measurement and erosion-corrosion tests. - Abstract: This paper investigates the synergism of mechanical and electrochemical factors in erosion-corrosion. The fact that active corrosion in the tailing slurry donates a small portion of total material loss indicates that the synergism results mainly from corrosion-enhanced erosion. As theoretically predicted, the erosion rates in corroding slurry under same hydrodynamic condition is a linear function of logarithmic corrosion rate, suggesting that the corrosion-induced surface plasticity is the dominate mechanism of corrosion-enhanced erosion. The reduced resistance to plastic deformation in surface layer while exposed to corroding media is demonstrated by the in situ micro-hardness measurements. The erosion-enhanced corrosion in flowing slurry of steel is a result of dynamic plastic deformation caused by erodent impingement.

Lu, B.T., E-mail: baotong.lu@swri.or [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alta., T6G 2G6 (Canada); Lu, J.F. [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alta., T6G 2G6 (Canada); Luo, J.L., E-mail: jingli.luo@ualberta.c [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alta., T6G 2G6 (Canada)

2011-03-15

383

The stress corrosion behaviour of molybdenum implanted stainless steel  

International Nuclear Information System (INIS)

The results of an investigation on the influence of molybdenum implantation on the electrochemical and stress corrosion cracking (SCC) behavior of AISI 304 L austenitic stainless steel are discussed. These results are compared with a conventional molybdenum-containing 316L stainless steel and with the unimplanted AISI 304 L steel. The composition depth profiling of implanted samples was examined by Auger Electron Spectroscopy (AES). The modification of the Mo-implanted steel was monitored by constant load tests, slow strain rate tests and potentiodynamic polarization tests. It appears from experimental results that the SCC susceptibility of implanted sample ranges between the two conventional alloys AISI 304 L and AISI 316 L. (Author)

384

Titanium containing high strength sulfuric acid corrosion resistant steel  

Energy Technology Data Exchange (ETDEWEB)

Ti containing low alloy steel free of Sb is found to have higher strength than and equivalent sulfuric acid corrosion (SAC) resistance to traditional SAC resistant steels in Cu-Cr-Sb system. SAC resistance of the Ti containing steel was investigated with potentiodynamic polarization, linear polarization resistance, electrochemical impedance spectroscopy, and weight loss measurements in a solution of 20 wt% H{sub 2}SO{sub 4} at 20 C. All measurements confirm that Ti addition is suitable for designing high strength SAC resistant steels. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Guo, Hairong; Li, Tingting; Li, Hualong; Toshihiko, Emi [Institute of Research of Iron and Steel, Shasteel, Zhangjiagang, Jiangsu (China)

2012-05-15

385

Corrosion inhibition of mild steel by aerobic biofilm  

International Nuclear Information System (INIS)

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

386

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

387

Corrosion testing of stainless steel-zirconium metal waste forms  

International Nuclear Information System (INIS)

Stainless steel-zirconium (SS-Zr) alloys have been developed as waste forms for the disposal of metallic waste generated during the electrometallurgical treatment of spent nuclear fuel. The waste forms incorporate 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 microstructures 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 immobilize and retain fission products very effectively and show potential for acceptance as high-level nuclear waste forms

388

Corrosion testing of stainless steel-zirconium metal waste form  

International Nuclear Information System (INIS)

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

389

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

390

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

391

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

392

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

393

Corrosion behavior of microwave-sintered austenitic stainless steel composites  

Energy Technology Data Exchange (ETDEWEB)

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.

Padmavathi, C. [Department of Materials and Metallurgical Engineering, Indian Institute of Technology, Kanpur, UP (India); Upadhyaya, A. [Department of Materials and Metallurgical Engineering, Indian Institute of Technology, Kanpur, UP (India)], E-mail: anishu@iitk.ac.in; Agrawal, D. [Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States)

2007-10-15

394

Monitoring and characterization of corrosion processes on steel in concrete  

OpenAIRE

The aim of this thesis was to perform a critical comparison of a number of different electrochemical and physical methods for the monitoring of steel corrosion in concrete. Initially, some tests were performed on medium-sized reinforced-concrete columns located in a natural marine environment, into which electrical resistance probes were embedded. Electrochemical noise was measured using a five-electrode assembly, and corrosion potentials and rates were determined by the galvanostatic puls...

C?esen, Ales?

2013-01-01

395

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

396

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

397

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.)

398

Protection of stainless-steels against corrosion in sulphidizing environments by Ce oxide coatings: X-ray absorption and thermogravimetric studies  

Science.gov (United States)

In this paper a study is reported concerning ceramic coatings containing cerium oxide, prepared by the sol-gel method, used to protect Incoloy 800H against sulphidation. When the coating is sintered in air at 850°C good protection is obtained. In an X-ray absorption spectroscopic study of the coatings it was observed that the best protective coating contains all cerium as Ce IV after pretreatment. After sulphidizing cerium was reduced to Ce III. Possible mechanisms to explain the protective properties are discussed.

Fransen, T.; Gellings, P. J.; Fuggle, J. C.; Van der Laan, G.; Esteva, J.-M.; Karnatak, R. C.

1985-01-01

399

Protection of stainless-steels against corrosion in sulphidizing environments by Ce oxide coatings: X-ray absorption and thermogravimetric studies  

OpenAIRE

In this paper a study is reported concerning ceramic coatings containing cerium oxide, prepared by the sol-gel method, used to protect Incoloy 800H against sulphidation. When the coating is sintered in air at 850°C good protection is obtained. In an X-ray absorption spectroscopic study of the coatings it was observed that the best protective coating contains all cerium as CeIV after pretreatment. After sulphidizing cerium was reduced to CeIII. Possible mechanisms to explain the protective pr...

Fransen, T.; Gellings, P. J.; Fuggle, J. C.; Laan, G.; Esteva, J. -m; Karnatak, R. C.

1985-01-01

400

Corrosion resistance of niobium-to-steel welded joints in boiling nitric acid  

International Nuclear Information System (INIS)

Corrosion resistance of niobium with stell welded joints in boiling nitric acid is studied by melting of steel only. It is shown that it corresponds to the 12Kh18N10T steel resistance and is determined by general corrosion. At the presence of interlayer of intermetallic compounds in the niobium with steel contact zone the corrosion resistance of joints decreases