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Showing papers on "Corrosion published in 2001"


Journal ArticleDOI
TL;DR: Corrosion inhibition efficiencies of heterocyclic, unsaturated (aromatic and nonaromatic) compounds (pyrimidines, benzothiazole derivatives, amino acids containing an aromatic part, pyridi...
Abstract: Corrosion inhibition efficiencies of heterocyclic, unsaturated (aromatic and nonaromatic) compounds (pyrimidines, benzothiazole derivatives, amino acids containing an aromatic part, pyridi...

735 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of degree of corrosion on the tensile strength of reinforcing steel bars was evaluated and the results indicated that the level of reinforcement corrosion does not influence the tensil strength of steel bars, calculated on the actual area of cross-section.

498 citations


Journal ArticleDOI
TL;DR: In this article, the feasibility of replacing chromate inhibitor pigments is assessed and the "gap" observable between the inhibitor performance of chromates and traditional non-chromate pigments are noted.

440 citations


Journal ArticleDOI
TL;DR: In this paper, the corrosion behavior of pure magnesium in aerated and deaerated Na 2 SO 4 solutions (0.01 and 0.1 M) was investigated by steadystate currentvoltage curves and electrochemical impedance measurements with a rotating disc electrode.

417 citations


Journal ArticleDOI
TL;DR: A series of nanocomposite materials that consisted of emeraldine base of polyaniline and layered montmorillonite (MMT) clay were prepared by effectively dispersing the inorganic nanolayers of MMT clay in organic polyanile matrix via in-situ polymerization.
Abstract: A series of nanocomposite materials that consisted of emeraldine base of polyaniline and layered montmorillonite (MMT) clay were prepared by effectively dispersing the inorganic nanolayers of MMT clay in organic polyaniline matrix via in-situ polymerization. Organic aniline monomers were first intercalated into the interlayer regions of organophilic clay hosts and followed by an one-step oxidative polymerization. The as-synthesized polyaniline−clay lamellar nanocomposite materials were characterized by infrared spectroscopy, wide-angle powder X-ray diffraction, and transmission electron microscopy. Polyaniline−clay nanocomposites (PCN) in the form of coatings with low clay loading (e.g., 0.75 wt %) on cold-rolled steel (CRS) were found much superior in corrosion protection over those of conventional polyaniline based on a series of electrochemical measurements of corrosion potential, polarization resistance, and corrosion current in 5 wt % aqueous NaCl electrolyte. The molecular weights of polyaniline ext...

366 citations


Journal ArticleDOI
TL;DR: In this paper, the grain boundary distributions were analyzed with special emphasis on grain boundary character along intergranular stress corrosion cracks and at crack arrest points, and it was established that only coherent twin Σ3 boundaries could be considered as special boundaries with regard to crack resistance.

335 citations


Journal ArticleDOI
TL;DR: In this article, a simple analytical model is formulated to demonstrate the mechanical consequences of corrosion-product buildup around the bar, and the service life is estimated as the time required for cover failure.
Abstract: Service life of concrete structures is limited by the susceptibility of the reinforcement to corrosion. Oxidation of iron leads to the formulation of various products (such as ferrous and ferric oxides), some of which occupy much greater volume than the original iron that gets consumed by the corrosion process. As corrosion progresses, these products accumulate, thereby generating expansive pressures on the surrounding concrete. The pressure builds up to levels that cause internal cracking around the bar and eventually leads to through cracking of the cover and spalling. Loss of cover marks the end of service life for corrosion-affected concrete structures, because at that stage the reinforcement loses its ability to develop its forces through bond and is no longer protected against further degradation from corrosion. In this paper, a simple analytical model is formulated to demonstrate the mechanical consequences of corrosion-product buildup around the bar. Service life is estimated as the time required ...

328 citations


Journal ArticleDOI
TL;DR: In this article, a WO3 film on a type 304 stainless steel plate can be charged by a UV-irradiated TiO2 coating on the same plate, in a 3 wt % NaCl aqueous solution, pH 5.
Abstract: TiO2 coatings are known to protect some metals, including type 304 stainless steel, from corrosion on the basis of its reductive energy generated under UV irradiation. A TiO2 coating is coupled with a WO3 coating as an electron pool, in which the reductive energy can be stored. A WO3 film on a type 304 stainless steel plate can be charged by a UV-irradiated TiO2 coating on the same plate, in a 3 wt % NaCl aqueous solution, pH 5. The charged WO3 coating can protect the stainless steel plate from the corrosion for a while even after the UV light is turned off. Thus, the TiO2 coating protects the plate and charges the WO3 coating during the day, and the charged WO3 coating protects the plate during the night. The charge−discharge cycles are repeatable. A TiO2−WO3 composite coating also has the same effects.

321 citations


Journal ArticleDOI
TL;DR: In this paper, the authors describe methods to assess concrete resistivity on site for various purposes related to corrosion and protection of reinforcement, based on the first draft of a forthcoming RILEM Technical Recommendation.

311 citations


Journal ArticleDOI
TL;DR: The corrosion susceptibility of Ti, Ti-6A1-4V and Ti-45Ni was studied in a buffered saline solution using anodic polarisation and electrochemical impedance measurements and found to depend on the nature of the electrode material and the presence of phosphate anions in the saline-buffered solution.

308 citations


Journal ArticleDOI
TL;DR: In this paper, electrochemical impedance spectroscopy (EIS) was employed to study the corrosion performance of two commercially available hard coatings (TiN and CrN) on mild steel substrate.

Book
01 Dec 2001
TL;DR: Alloying: Understanding the Basics as mentioned in this paper is a comprehensive guide to the influence of alloy additions on mechanical properties, physical properties, corrosion and chemical behavior, and processing and manufacturing characteristics.
Abstract: Alloying: Understanding the Basics, is a comprehensive guide to the influence of alloy additions on mechanical properties, physical properties, corrosion and chemical behavior, and processing and manufacturing characteristics. The coverage considers alloying, to include any addition of an element or compound that interacts with a base metal to influence properties. Thus, the book addresses the beneficial effects of major alloy additions, inoculants, dopants, grain refiners, and other elements that have been deliberately added to improve performance, as well as the detrimental effects of minor elements or residual (tramp) elements included in charge materials, or that result from improper melting or refining techniques. The content is presented in a concise, user-friendly format. Numerous figures and tables are provided. The coverage has been weighted to provide the most detailed information on the most industrially important materials. Contents include: Principles of alloying; Cast irons; Carbon and alloy steels; High-strength low-alloy steels; Tool steels; Maraging and high-fracture-toughness steels; Austenitic manganese steels; Stainless steels; Superalloys; Refractory metal alloys; Ordered intermetallics (nickel, iron, and titanium aluminides); Aluminum alloys; Titanium alloys; Magnesium alloys; Copper alloys; Nickel alloys; Zinc alloys; Tin alloys; Lead alloys; Cobalt alloys; Noble metal alloys; Special-purpose materials (cemented carbides, cermets, low-expansion alloys, electrical contact alloys, magnetic alloys); Index.

Journal ArticleDOI
TL;DR: A literature review summarizes the results of almost 300 peer-reviewed articles relevant to the drinking water industry, and a review of potential implications of upcoming regulations for iron corrosion is also included.
Abstract: This literature review summarizes the results of almost 300 peer-reviewed articles relevant to the drinking water industry, and a review of potential implications of upcoming regulations for iron corrosion is also included.

Journal ArticleDOI
TL;DR: Although chromate contributes to iron surface passivation, the removal rates are still sufficiently fast for in situ iron barriers to be effective for Cr(VI) removal at most environmentally relevant concentrations.
Abstract: Permeable reactive barriers containing zerovalent iron are being increasingly employed for in situ remediation of groundwater contaminated with redox active metals and chlorinated organic compounds. This research investigated the effect of chromate concentration on its removal from solution by zerovalent iron. Removal rates of aqueous Cr(VI) by iron wires were measured in batch experiments for initial chromium concentrations ranging from 100 to 10 000 μg/L. Chromate removal was also measured in columns packed with zerovalent iron filings over this same concentration range. Electrochemical measurements were made to determine the free corrosion potential and corrosion rate of the iron reactants. In both the batch and column reactors, absolute rates of chromium removal declined with increasing chromate concentration. Corrosion current measurements indicated that the rate of iron corrosion decreased with increasing Cr(VI) concentrations between 0 and 5000 μg/L. At a Cr(VI) concentration of 10 000 μg/L, Tafel ...

Journal ArticleDOI
TL;DR: The sol-gel method is being investigated as an environmentally compliant alternative for chromate-based conversion coatings currently in use as mentioned in this paper, and an overview of recent advances in the use of solgel derived coatings for improved corrosion resistance of aluminum and steel metal surfaces is given.

Journal ArticleDOI
TL;DR: In this paper, the corrosion behavior of as-cast magnesium alloys (AM50, AZ91, and AZ91Si) was investigated in a 0.1 M sodium sulfate solution at the corrosion potential (E corr ) using electrochemical impedance spectroscopy.
Abstract: The corrosion behavior of as-cast magnesium alloys (AM50, AZ91, and AZ91Si) was investigated in a 0.1 M sodium sulfate solution at the corrosion potential (E corr ) using electrochemical impedance spectroscopy. Transmission electron microscopy was used to analyze the corrosion product layer, and phase shifting interferometric microscopy was carried out to characterize the reactivity of intermetallic particles. Due to its microstructure, the AM50 alloy presented uniform corrosion during immersion, whereas corrosion of the AZ91 alloys began in the grain body and progressively spread to the eutectic areas. For the AZ91 alloys, the dissolution of the α-eutectic phase led to a strong aluminum enrichment of the corrosion product layer and, when a threshold was reached in the level of Al 2 O 3 in the magnesium oxide (or hydroxide) layer a change of phenomenology occurred in the impedance diagrams. In addition, electrochemical results revealed that an increase of silicon concentration for the AZ91 alloys decreased the corrosion resistance, This was attributed to an increase of the number of Mg 2 Si particles, accelerating the dissolution n of eutectic areas.

Journal ArticleDOI
TL;DR: In this article, the most accurate method is based on the modulated confinement of the current which enables us to limit the steel area polarized by the current, and a brief basis of the correct measurement of the corrosion rate is given.

Journal ArticleDOI
TL;DR: The authors' studies were able to identify important differences between corrosion scales found in two different water distribution systems and establish the role of corrosion scales in the mechanism of iron release from corroded pipes.

Journal ArticleDOI
TL;DR: In this article, the authors show that the presence of molybdenum as an alloying element in stainless steels reduces the incidence of both nucleations and metastable pits.

Journal ArticleDOI
TL;DR: In this paper, a potential perturbation signal by one or more sine waves will generate current responses at more frequencies than the corresponding sine wave wave wave frequencies, which is a nonlinear electrochemical phenomenon.
Abstract: Since a corrosion process is a nonlinear electrochemical phenomenon, a potential perturbation signal by one or more sine waves will generate current responses at more frequencies than the ...

Journal ArticleDOI
TL;DR: In this article, the photoelectrochemical behavior of type 304 stainless steel (SUS 304) with TiO 2 thin film coatings, applied by a spray pyrolysis technique, for the purpose of cathodic photoprotection of the steel from corrosion was investigated.
Abstract: We investigated the photoelectrochemical behavior of type 304 stainless steel (SUS 304) with TiO 2 thin film coatings, applied by a spray pyrolysis technique, for the purpose of cathodic photoprotection of the steel from corrosion. The photopotential of TiO 2 -coated SUS 304 was -350 mV vs. Ag/AgCl in an aerated aqueous solution containing 3 wt NaCl (pH 7) under illumination with 10 mW cm -2 ultraviolet (UV) light, which was more negative than the corrosion potential of the bare steel (-100 mV). The photopotential did not change in aqueous solutions containing from 0.01 to 5 wt % NaCl. No corrosion of TiO 2 -coated steel was observed at pH values greater than 3 in 3 wt % NaCl aqueous solution under UV illumination. TiO 2 films with coverages greater than 30% achieved photoprotection ability at pH 6. When the UV light intensity was 3 mW cm -2 , that is, comparable with a typical daylight UV intensity in Tokyo the photopotential of TiO 2 -coated SUS 304 was -220 mV in an aerated 3 wt % NaCl aqueous solution. In addition, the bleaching of methylene blue dye was confirmed on TiO 2 -coated SUS 304 under 1 mW cm -2 UV illumination. We conclude that TiO 2 thin film-coated SUS 304 exhibits both a cathodic photoprotection effect against corrosion and the previously reported photocatalytic self-cleaning effect.

Journal ArticleDOI
TL;DR: In this paper, the effects of pitting corrosion on the fatigue behavior of bare 7075-T6 aluminum alloy were investigated and it was shown that pitting degradation decreased the fatigue lives by a factor of about 6 to 8.
Abstract: The effects of pitting corrosion on the fatigue behavior of bare 7075-T6 aluminum alloy were investigated. Pitting corrosion decreased the fatigue lives by a factor of about 6 to 8. The fatigue lives were also calculated assuming an equivalent initial flaw corresponding to pits of average and maximum dimensions. The measured fatigue lives generally agreed with the predictions using the average rather than the maximum pit size as the initial crack size. This result could be explained by the pit size distributions offering a significantly larger population of pits near the average size. This work has demonstrated the promise of standardized spray tests for obtaining quantitative measures of corrosion that can be used as inputs in analytical models for fatigue life prediction for evaluating integrity of aircraft structures.

Journal ArticleDOI
01 Nov 2001-Wear
TL;DR: In this article, a comparative wear corrosion study of pure nickel and Ni-SiC nano-structured composite coating was carried out on an apparatus constructed in the laboratory of Electrochemistry, Department of Materials Engineering of Trento University.

Journal ArticleDOI
TL;DR: In this paper, the results of combined wear and corrosion tests showed that the corrosion properties of the sprayed coatings strongly affect the materials loss rate under wear corrosion conditions, and that the coating with a less corrosion resistant matrix presents enhanced erosion.
Abstract: In order to protect machining parts against wear and corrosion, they are coated by cermet coatings. The coatings consist of WC or Cr3C2 particles in a metal binder, which can be a pure metal or a mixture consisting of Ni, Cr, Co. The examined coatings were produced by high velocity oxy-fuel (HVOF) spraying and were investigated with regard to erosion and corrosion resistance. The combined erosion corrosion tests were carried out at ambient temperature in 0.1 M NaOH and 0.1 M H2SO4 solutions containing sand. Information about the corrosion resistance was gained from electrochemical polarization measurements and salt spray test (NaCl solution). The results of combined wear and corrosion tests showed that the corrosion properties of the sprayed coatings strongly affect the materials loss rate under wear corrosion conditions. Coatings with a less corrosion resistant matrix present enhanced erosion, also. The erosion mechanism of the carbide coatings seams to be controlled by the skeletal network of the carbides. For comparison, flame and plasma sprayed hard Cr2O3 coatings were examined. Due to the low electrical conductivity the corrosion rate of these coatings was very low. Under erosion conditions the hard Cr2O3 coatings exhibited a high erosion rate and the erosion mechanism seems to be that of the brittle erosion due to grain-by-grain removal of oxide grains during impact.

Journal ArticleDOI
Jun Zhao1, Lin Xia1, A. Sehgal1, D. Lu1, Richard L. McCreery1, Gerald S. Frankel1 
TL;DR: In this paper, the effect of chromate in solution on anodic dissolution kinetics under potentiostatic control was investigated and it was shown that large chromate concentrations were needed to have an effect.
Abstract: Various effects of chromate conversion coatings (CCCs) and chromate in solution on the corrosion of AA2024-T3 and pure Al are studied in this work. Raman spectroscopy was used to investigate the nature of chromate in CCCs through a comparison with the spectra of known standards and artificial Cr(III)/Cr(VI) mixed oxides. Chromate was shown to be released from CCCs and to migrate to and protect a nearby, uncoated area in the artificial scratch cell. However, experiments investigating the effect of chromate in solution on anodic dissolution kinetics under potentiostatic control indicated that large chromate concentrations were needed to have an effect.

Journal ArticleDOI
TL;DR: In this paper, the effects of N alloying through different processing and manufacturing routes on metallurgical, mechanical, corrosion and wear properties of high N-containing stainless steels have been studied.

Journal ArticleDOI
TL;DR: In this paper, four series of reinforced concrete specimens have been studied over 3 years exposure in a 100% relative humidity atmosphere, and the results confirmed previous results obtained in alkaline medium, i.e., the redox activity in the rebar's oxides layer greatly influences the electrochemical behaviour of rebars in the passivity potential domain.

Journal ArticleDOI
TL;DR: In this article, reinforced steel bars with three types of surface conditions (as-received mill scale, prerusted in 3.5% sodium chloride [NaCl] solution, or sandblasted) were exposed in open-circuit immersion (OCI) tests in pH 12.6 saturated calcium hydroxide (Ca[OH]2) solution (SCSSCS) and pH 13.3 simulated concrete pore solutions.
Abstract: Reinforcing steel bars with three types of surface conditions (as-received mill scale, prerusted in 3.5% sodium chloride [NaCl] solution, or sandblasted) were exposed in open-circuit immersion (OCI) tests in pH 12.6 saturated calcium hydroxide (Ca[OH]2) solution (SCS) and pH 13.3 (SPS1) and pH 13.6 (SPS2) simulated concrete pore solutions. These solutions were free of chlorides at the beginning of the test to allow the steel specimens to passivate. Then the chloride concentration ([Cl−]) was increased in several steps. The corrosion potential was monitored, and electrochemical impedance spectroscopy tests were performed periodically on selected specimens. It was found that active corrosion for all three surface conditions tookplace in the pH 12.6 SCS andpH 13.3 SPS1, when the [Cl−] reached threshold levels. However, sustained active corrosion of steel was not found inpH 13.6 SPS2 in a testing period of ∼ 2 years, although the final [Cl−] in that solution reached 3.0 M. Removing the mill scale or ...

Journal ArticleDOI
TL;DR: In this article, the corrosion resistance of mild steel coated with single layered and multi-layered TiN and CrN coatings has been studied, and it is shown that applying four layers of coating can enhance the corrosion performance of PVD TiN/CrN coated mild steel.
Abstract: The corrosion resistance of mild steel coated with single layered and multi-layered TiN and CrN coatings has been studied. The base material was coated with TiN and CrN by an electron-beam plasma-assisted physical vapour deposition (PAPVD) technique. ‘Single’ layers of TiN or CrN, which normally include an interlayer (approx. 100–200 nm) of Ti or Cr under the main TiN or CrN film, were prepared; four layers of TiN (or CrN) were produced by four sequential repetitions of the single-layer process. The microstructural features and corrosion performance were then compared. It is shown that applying four layers of coating can enhance the corrosion performance of PVD TiN and CrN coated mild steel. The corrosion resistance improvement is not only attributed to the increase in thickness, but also to the internal microstructure and phase composition. CrN coatings produced in this work proved to be particularly promising in terms of corrosion resistance, owing to their dense non-columnar structure which contained a mixture of three phases: Cr (b.c.c.), Cr2N (hexagonal) and CrN (f.c.c.). Mild corrosion reactions were observed in CrN coated steel during various electrochemical tests in aqueous salt solution, indicating that inter-phase corrosion had caused a redistribution of the current flow, so as to eliminate current concentration at small through-coating pinholes. This prevented rapid galvanic attack at the coating/substrate interface. More importantly however, in comparison with the columnar structure of TiN coatings, the dense structure with fine equiaxed crystallites made the CrN coatings less permeable to the corrosive medium.

Journal ArticleDOI
TL;DR: In this paper, a new class of corrosion inhibitors, namely, 2,5-bis(4-dimethylaminophenyl)-1,3,4-thiadiazole (DAPT), was synthesized and its inhibiting action on the corrosion of mild steel in 1 M HCl and 0.5 M H2SO4 at 30 °C was investigated by various corrosion monitoring techniques.
Abstract: An example of a new class of corrosion inhibitors, namely, 2,5-bis(4-dimethylaminophenyl)-1,3,4-thiadiazole (DAPT) was synthesized and its inhibiting action on the corrosion of mild steel in 1 M HCl and 0.5 M H2SO4 at 30 °C was investigated by various corrosion monitoring techniques. A preliminary screening of the inhibition efficiency was carried out using weight loss measurements. At constant acid concentration, inhibitor efficiency increases with concentration of DAPT and is found to be more efficient in 0.5 M H2SO4 than in 1 M HCl. Potentiostatic polarization studies showed that DAPT is a mixed-type inhibitor. The effect of temperature on the corrosion behaviour of mild steel in 1 M HCl with addition of DAPT was studied in the temperature range from 25 to 60 °C. Its was shown that adsorption is consistent with the Langmuir isotherm for 30 °C. The negative free energy of adsorption in the presence of DAPT suggests chemisorption of thiadiazole molecules on the steel surface.