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Showing papers on "Corrosion published in 1994"


Journal ArticleDOI
TL;DR: In this article, the relative importance of the above reactions on glass degradation as a function of solution pH and composition, temperature and stress level was evaluated for silica, alkali silicate, and alkali boro- and aluminosilicate glasses.
Abstract: Dissolution, selective leaching, and stress-corrosion cracking are all processes which can degrade the performance of silica and silicate glasses exposed to aqueous environments. Reactions which corrode glass in water include hydration, hydrolysis and condensation, and ion-exchange processes. Techniques such as solid-state nuclear magnetic resonance, Raman and Fourier transform infrared spectroscopies, pH stat titrations and elemental depth profiling have been used to establish the relative importance of the above reactions on glass degradation as a function of solution pH and composition, temperature and stress level. This paper reviews results obtained for silica, alkali silicate, and alkali boro- and aluminosilicate glasses. For most glasses, the rate at which water enters the glass structure controls the kinetics of the other glass-water reactions, explaining the corrosion characteristics of different glass compositions.

523 citations


Journal ArticleDOI
TL;DR: In this paper, a corrosion test of Co-Pt alloys was carried out in a PAFC and the results showed that the Pt atoms on particle surfaces of both alloys dissolved easily in the acid.
Abstract: Co-Pt alloys were studied in detail by a corrosion test under phosphoric acid fuel cell (PAFC) conditions on the well-defined crystallographic structures for a typical combination of the alloy catalysts used in PAFCs, examining the long-life stabilities of the structures and the catalytic activities for O[sub 2] electroreduction. The ordered (O) and disordered (D) alloys at the same particle sizes can be obtained by heat-treating the mother alloy in different temperature sequences. The O-alloy exhibits a specific activity 1.35 times higher than the D-alloy before the corrosion test, but shows less activity after the corrosion test, due to a higher degradation in the O-alloy activity as compared with that of the D-alloy. It was found that the Co atoms on particle surfaces of both alloys dissolved easily in the acid. This is followed by a second slow dissolution from inside the alloy particles probably due to the protective action by a monolayer thickness of Pt remaining on the alloy surfaces, but the loss of Co in the second stage dissolution for the O-alloy is higher by several percentage points compared to that of the D-alloy. It was also found that the Pt content does not change on the catalyst supportmore » even after 50 h of corrosion test, but the pure Pt phase is formed in the corrosion product, where the phase for the O-alloy grows faster than that for the D-alloy with corrosion time. Based on these results, obtained by chemical, x-ray diffraction, and transmission electron microscopy with energy dispersive spectroscopy analyses, the corrosion for Pt alloy catalysts is clearly explained: after the dissolution of Co atoms in the first surface layer of alloys, both Co and Pt dissolve out simultaneously from small-size alloy particles and the Pt redeposits on the surfaces of large-size alloy particles. It is concluded that the D-alloy is preferable to the O-alloy from the viewpoint of the stabilities in the structure and the electrocatalytic activity.« less

393 citations


Journal ArticleDOI
TL;DR: Although intergranular stress corrosion cracking (IGSCC) of high-pressure gas pipelines has been known for more than 20 years, a transgranular form (TGSCC) was detected more recently as discussed by the authors.
Abstract: Although intergranular stress corrosion cracking (IGSCC) of high-pressure gas pipelines has been known for more than 20 years, a transgranular form (TGSCC) was detected more recently. Inst...

246 citations


Journal ArticleDOI
TL;DR: In this article, several recently developed experimental techniques are applied to such corrosion systems to elucidate the fundamental corrosion processes for polymer coated metals, and the combined application of these techniques leads to a corrosion model, which explains the corrosion protection of metals by polymers.

222 citations


Journal ArticleDOI
TL;DR: In this article, the chemical inertness and corrosion resistance of a boron-doped diamond thin film electrode, grown by chemical vapor deposition (CVD), have been studied during potential cycling (PC) for 2 h in a solution of at 50°C.
Abstract: The chemical inertness and corrosion resistance of a boron‐doped diamond thin film electrode, grown by chemical vapor deposition (CVD), have been studied during potential cycling (PC) for 2 h in a solution of at 50°C. Similar experiments were performed on highly ordered pyrolytic graphite (HOPG) and glassy carbon (GC), for comparison. The physicochemical properties of the electrode surface were characterized before and after PC by cyclic voltammetry, optical and scanning electron microscopy, Raman spectroscopy, and ac impedance spectroscopy. The results indicated that the diamond electrode possesses a superior degree of chemical inertness and corrosion resistance, has no microstructural damage nor was surface oxidation observed after PC. HOPG and GC surfaces, on the other hand, exhibited severe corrosion in the form of surface cavitation, pitting, and oxidation. The relative degree of microstructural damage and surface oxidation increased in the order of diamond . This work represents some of the initial efforts at systematically characterizing how the physical, chemical, and electronic properties of conductive diamond thin films are affected during exposure to electrochemical conditions (i.e., solvent, electrolyte, and applied potential).

218 citations


Journal ArticleDOI
01 Dec 1994-JOM
TL;DR: In this paper, the solubilities for various metal oxides in fused Na2SO4 have been measured, and these show remarkable agreement with the theoretical expectations from the thermodynamic phase stability diagrams for the relevant Na-Metal-S-O systems.
Abstract: Hot corrosion is the accelerated oxidation of materials at elevated temperatures induced by a thin film of fused salt deposit. Because of its high thermodynamic stability in the mutual presence of sodium and sulfur impurities in an oxidizing gas, Na2SO4 is often found to be the dominant salt in the deposit. The corrosive oxyanion-fused salts are usually ionically conducting electrolytes that exhibit an acid/base chemistry, so that hot corrosion must occur by an electrochemical mechanism that may involve fluxing of the protective oxides. With the aid of high-temperature reference electrodes to quantify an acid/base scale, the solubilities for various metal oxides in fused Na2SO4 have been measured, and these show remarkable agreement with the theoretical expectations from the thermodynamic phase stability diagrams for the relevant Na-Metal-S-O systems. The solubilities of several oxides infused Na2SO4-NaVO3 salt solutions have also been measured and modeled. Such information is important both in evaluating the corrosion resistance of materials and in interpreting any oxide fluxing/reprecipitation mechanisms. Various electrochemical measurements have identified the S2O7 2− anion (dissolved SO3) as the oxidant that is reduced in the hot corrosion process. Electrochemical polarization studies have elucidated the corrosion reactions and clarified the corrosion kinetics of alloys. Mechanistic models for Type I and Type II hot corrosion are discussed briefly.

175 citations


Book
01 Jan 1994

171 citations


Journal ArticleDOI
TL;DR: In this article, the extensive use of thin films in the manufacture of microelectronic devices and for protection against wear and corrosion has stimulated considerable interest in their mechanical properties, and a number of applications have been proposed.
Abstract: The extensive use of thin films in the manufacture of microelectronic devices and for protection against wear and corrosion has stimulated considerable interest in their mechanical properties. In t...

165 citations


Journal ArticleDOI
TL;DR: In this paper, the corrosion of metal matrix composites (MMCs) is reviewed with emphasis on relating MMC corrosion behaviour to the electrochemical and chemical properties of MMC constituents.
Abstract: The corrosion of metal matrix composites (MMCs) is reviewed with emphasis on relating MMC corrosion behaviour to the electrochemical and chemical properties of MMC constituents. Galvanic corrosion between the reinforcement constituent and the metal matrix governs the corrosion behaviour of many MMCs. Other factors such as residual contaminants of MMC processing and the formation of interphases between reinforcement and matrix can also have pronounced effects on MMC corrosion behaviour. The lack of inherent resistance to corrosion of some MMCs requires that they be coated with organic or inorganic coatings for protection. Although the ultimate goal is to engineer and design MMCs to have good inherent resistance to corrosion (while maintaining excellent mechanical properties), no significant breakthroughs have been achieved in this area for MMCs that are typically prone to corrosion (e.g. graphite-aluminium MMCs). In this review, aluminium, magnesium, lead, depleted uranium, and stainless steel MMCs...

164 citations


Journal ArticleDOI
TL;DR: In this article, the effects of mass transport, corrosion products and biofilm formation on corrosion kinetics of five copper alloys, four stainless steels and titanium grade 2 exposed to natural and artificial seawater were determined.

145 citations


Journal ArticleDOI
TL;DR: In this article, the influence of aminophenols on the corrosion and hydrogen permeation of mild steel in 1 M HCl and 0.5 M H2SO4 has been studied using weight loss and gasometric measurements and various electrochemical techniques.
Abstract: The influence of aminophenols on the corrosion and hydrogen permeation of mild steel in 1 M HCl and 0.5 M H2SO4 has been studied using weight loss and gasometric measurements and various electrochemical techniques. All the isomers of aminophenol inhibit the corrosion of mild steel in 1 M HC1 and accelerate it in 0.5 M H2SO4. They behave predominantly as cathodic inhibitors. Aminophenols, except PAP in I M HCI, enhance the permeation current in both the acids. The adsorption of PAP on the mild steel surface in 1 M HCl obeys the Langmuir adsorption isotherm. Surface analysis and ultraviolet spectral studies are also carried out to establish the mechanism of corrosion inhibition and acceleration of mild steel in acidic solutions.

D Brondel, R Edwards, A Hayman, D Hill, S Mehta, T Semerad 
01 Apr 1994
TL;DR: In this paper, the role of corrosion agents such as drilling and production fluids is reviewed, along with an explanation of the chemical causes of corrosion, and methods of control and techniques to monitor corrosion are discussed.
Abstract: Corrosion costs the oil industry billions of dollars a year, a fact that makes the role of the corrosion engineer an increasingly important one. Attention is paid to how corrosion affects every aspect of exploration and production, from offshore rigs to casing. Also the role of corrosion agents such as drilling and production fluids is reviewed. Methods of control and techniques to monitor corrosion are discussed, along with an explanation of the chemical causes of corrosion. 21 figs., 32 refs.

Journal ArticleDOI
TL;DR: Application of the mixed-potential theory shows that titanium in coupling with the alloys studied will be under either cathodic or anodic control.


Journal ArticleDOI
TL;DR: In this article, the effect of temperature and molecular structure on the inhibition efficiency of four amino acids for the corrosion of a copper electrode in a 1 M HCl solution was investigated at different temperatures ranging from 25 to 55 °C.

Journal ArticleDOI
TL;DR: In this article, the inhibitive action of ortho-methoxy substituted polyaniline, a new class of conducting polymer, on the corrosion of iron in acidic chloride solution has been evaluated by Electrochemical Impedance Spectroscopy (EIS), Linear Polarization Resistance (LPR), Weight Loss (WL) and by the Logarithmic Polarization Technique (LPT).

Journal ArticleDOI
TL;DR: In this paper, electrical impedance studies were conducted on an epoxy polyamide-coated AISI1010 steel (UNS G10100) and a epoxy/chromate conversion coated magnesium alloy (Mg) alloy ZE41A-T5 (ZM16410) alloy.
Abstract: Electrochemical impedance studies were conducted on an epoxy polyamide-coated AISI1010 steel (UNS G10100) and an epoxy/chromate conversion-coated magnesium (Mg) alloy ZE41A-T5 (UNS M16410)...

Journal ArticleDOI
TL;DR: In this article, the T1 (Al2CuLi) intermetallic compound was synthesized in bulk form for characterization of its electrochemical behavior in chloride solutions by conventional direct current (DC) techniques.
Abstract: The T1, (Al2CuLi) intermetallic compound was synthesized in bulk form for characterization of its electrochemical behavior in chloride solutions by conventional direct current (DC) techniques. Results indicated T1, was active with respect to its microstructural suroundings in artificially aged Aluminum Association (AA) 2090 (UNS A92090) (Al 2.1% Li-2.6% Cu) and preferential dissolution of T1 precipitates strongly influenced localized corrosion behavior of the alloy. Subgrain boundaries in artificially aged AA 2090 were particularly susceptible to localized attack because of high concentrations of T1. The role of T1, in preferential subgrain boundary attack in a chloride-free sulfate solution also was investigated.

Journal ArticleDOI
TL;DR: In this paper, the rate of corrosion of hardened cement paste in solutions of nitric, hydrochloric, sulphuric, acetic and formic acids was compared and the results made it possible to obtain the relationships expressing the influence of concentration and the time of action of acid solutions on the depth of corrosion.

Journal ArticleDOI
TL;DR: In this paper, the grain boundary engineering (GME) approach was used to solve the problem of intergranular stress corrosion cracking in Ni-Cr-Fe alloy coatings.
Abstract: Nickel-based alloys used in nuclear steam generator tubing have been found to be susceptible to intergranular stress corrosion cracking while in service. Following a recently developed model, grain boundary engineering concepts may be used to alleviate these concerns. This paper presents a report on the grain refinement approach in the proposed model which results in a higher probability of arresting stress corrosion cracks before reaching a critical length at which failure occurs. For this purpose, an electroplating system was developed to produce ternary Ni-Cr-Fe alloy coatings. Electroplating conditions are given for the production of Alloys 600 and 690 having an average grain size in the range 100-250 nm.

Journal ArticleDOI
TL;DR: In this article, in situ atomic force microscopy was used in conjunction with microlithography and scanning Auger electron spectroscopy to monitor localized corrosion near iron-rich inclusions in Al-6061-T6 immersed in 0.6M NaCl.
Abstract: In situ atomic force microscopy was used in conjunction with microlithography and scanning Auger electron spectroscopy to monitor localized corrosion near iron-rich inclusions in Al-6061-T6 immersed in 0.6M NaCl and also sulfur-rich inclusions in 304 stainless steel (SS-304) in 0.5M NaCl. The local rate of aluminum corrosion was found to depend on the shape of the nearby iron-rich inclusion. At the corrosion potential, trenches were observed to form in the aluminum host matrix adjacent to the inclusions, and the corrosion sites gradually evolved into circular shapes owing to dissolution. During the dissolution process, the width of the dissolution area was an order of magnitude greater than the depth. Application of a 400 mV cathodic overpotential prevented corrosion initiation, while application of a 500 mV cathodic overpotential greatly accelerated the dissolution rate in comparison with that at the rest potential. On SS-304, exposure to 0.5M NaCl was accompanied by formation of deposits, which decorated the inclusion surface as well as the surrounding area up to four times the radius of the original inclusion.

Journal ArticleDOI
TL;DR: The performance of black steel, galvanized steel, and epoxy-coated steel in concrete was investigated in this article, where samples were exposed to cyclic salt water wetting and drying or to a contin...
Abstract: The corrosion performance of black steel, galvanized steel, and epoxy-coated steel in concrete was investigated. Samples were exposed to cyclic salt water wetting and drying or to a contin...

Journal Article
Bundy Kj1
TL;DR: In this paper, the authors focus on the nature of the body's environment as it affects in vivo electrochemical phenomena, that is, the chemical, mechanical, biological, and bioelectrical phenomena that affect the behavior and performance of biomaterials.
Abstract: Metallic materials are used extensively as orthopedic implants, dental materials, sensing elements of bioelectrodes, and other applications The electrochemical behavior of these biomaterials is of interest for a variety of reasons The corrosion resistance of an implant material influences its functional performance and durability and is a primary factor governing biocompatibility Among the aspects affecting biocompatibility are the amounts and forms of released corrosion products and their disposition in the body after release Electrochemical principles are very useful for understanding the factors affecting corrosion resistance and also form the foundation for many biosensors that measure the concentration of various chemical entities (including released corrosion products and naturally occurring substances) Many electrochemical measurement techniques have been used to study biomaterials for years (eg, polarization curve measurement), while others (such as polarography and AC impedance methods) have been applied more recently This work focuses on four main topics The first is the nature of the body's environment as it affects in vivo electrochemical phenomena, that is, the chemical, mechanical, biological, and bioelectrical phenomena that affect the behavior and performance of biomaterials The second deals with methodology--the techniques used for corrosion measurement and concentration determination, the appropriate environment (laboratory, cell culture, in vivo, etc), and experimental problems encountered The third topic treated is the knowledge accumulated regarding the performance of implant alloys in various applications, for example, the forms of corrosion to which they are susceptible, etc Finally, improvements that may come about in the future regarding both materials and testing methodology are considered

Journal ArticleDOI
TL;DR: In this paper, the corrosion of Fe−28Cr, Ni−28C, Co−28c, and pure chromium in a number of gas atmospheres made up of CO−CO2(−N2) was studied at 900°C.
Abstract: The corrosion of Fe−28Cr, Ni−28Cr, Co−28Cr, and pure chromium in a number of gas atmospheres made up of CO−CO2(−N2) was studied at 900°C. In addition, chromium was reacted with H2−H2O−N2, and Fe−28Cr was reacted with pure oxygen at 1 atm. Exposure of pure chromium to H2−H2O−N2 produced a single-phase of Cr2O3. In a CO−CO2 mixture, a sublayer consisting of Cr2O3 and Cr7C3 was formed underneath an external Cr2O3 layer. Adding nitrogen to the CO−CO2 mixture resulted in the formation of an additional single-phase layer of Cr2N next to the metal substrate. Oxidizing the binary alloys in CO−CO2−N2 resulted in a single Cr2O3 scale on Fe−28Cr and Ni−28Cr, while oxide precipitation occurred below the outer-oxide scale on Co−28Cr, which is ascribed to the slow alloy interdiffusion and possibily high oxygen solubility of Co−Cr alloys. Oxide growth followed the parabolic law, and the rate constant was virtually independent of oxygen partial pressure for Fe−28Cr, but varied between the different materials, decreasing in the order chromium >Fe−28Cr>Ni(Co)−28Cr. The formation of an inner corrosion zone on chromium caused a reduction in external-oxide growth rate. Permeation of carbon and nitrogen through Cr2O3 is thought to be due to molecular diffusion, and it is concluded that the nature of the atmosphere affects the permeability of the oxide.

Journal ArticleDOI
TL;DR: In this paper, the authors describe methods to study the initiation and formation of localized corrosion pits on stainless steel and aluminium samples using a scanned probe microscope, the scanning electrochemical microscope (SECM).

Journal ArticleDOI
TL;DR: In this article, a four-year experimental study on carbon dioxide (CO2) corrosion of carbon (C) steel in two-phase flow was conducted in a gas and water loop that permitted control and regulation of relevant parameters.
Abstract: Results were presented from a four-year experimental study on carbon dioxide (CO2) corrosion of carbon (C) steel in two-phase flow. Tests were carried out in a gas and water loop that permitted control and regulation of relevant parameters. Flow rates of gas and water were regulated independently to obtain a number of two-phase flow regimes, such as bubble flow and slug flow. In more than 20 long-term experiments lasting from one to several weeks each, pH was varied from 4 to 7 while the temperature was held at 20°C, 40°C, 60°C, and 80°C in different experiments. Corrosion rates were monitored continuously in time with a radiation detection technique. Scanning electron microscopy analysis and x-ray analysis of the specimen surface and cross section were done on selected specimens after each experiment. It was found that, in cases where the formation of protective films is difficult, flow could have a “positive” role by eroding the iron carbide films that otherwise would accelerate corrosion by ga...

Journal ArticleDOI
TL;DR: In this article, the effect of σ-phase precipitation at 800°C on the corrosion behavior in seawater was investigated and a serious deterioration of corrosion resistance was found after aging times longer than 7 min, resulting in a drop of both the critical crevice corrosion temperature (CCT) and the breakdown potential (Ebd).

Journal ArticleDOI
TL;DR: In this article, the influence of chloride ion concentration and pH on the corrosion behavior of 8090 and 2014 alloys has been studied in NaC1 solution using a potentiodynamic polarization technique.
Abstract: The influence of chloride ion concentration and pH (2.0, 6.0 and 11.0) on the corrosion behaviour of 8090 (A1-Li-Cu-Mg-Zr) and 2014 (A1-4.4%Cu) alloys has been studied in NaC1 solution using a potentiodynamic polarization technique. The corrosion rate for both the alloys was high at pH values of 2.0 and 11.0 as compared to that at pH 6.0, and the rate increased in chloride ion concentration at all pH levels. A similar result was found for the passive current density. Increase in pH changed the slope of the cathodic polarization curve by changing the cathodic reaction. Increasing the chloride ion concentration decreased the cathodic reaction rate. On the other hand, the anodic reaction rate increased with increase in chloride ion concentration. The open circuit corrosion potential and the pitting potential shifted in the active (negative) direction with increasing pH and chloride ion concen- tration. The $i_p$ values for 8090-T851 were slightly lower than those for 2014-T6.

Journal ArticleDOI
TL;DR: In this article, an analysis of the corrosion process taking place in nitric acid enabled the authors to calculate the thickness of the brown colored zone in the layer of corrosion products which contained an increased content of hydrated Fe 2 O 3, and thus verify various zone formation theories.

Journal ArticleDOI
TL;DR: In this paper, surface analytical and electrochemical experiments aimed at characterizing the structure, composition, and barrier properties of talc coatings were conducted, and the solution chemistry involved in talc formation was studied.
Abstract: Aluminum (Al) and Al alloys exhibit unusual passivity when immersed in alkaline lithium (Li) salt solutions. This passivity is a result of precipitation of a continuous, polycrystalline talc coating. Talc coatings persist when removed from the Li salt solution and offer increased corrosion protection during exposure to aggressive environments. Efforts to develop a low-cost, low-toxicity, easily applied corrosion-resistant coating for Al are ongoing. Surface analytical and electrochemical experiments aimed at characterizing the structure, composition, and barrier properties of talc coatings were conducted. The solution chemistry involved in talc formation was studied, and the conditions under which coatings form readily were established. Results showed coatings formed by immersion in an alkaline Li salt bath followed by a low-temperature (≤ 100°C) heat treatment in air or water provided barrier properties that compared favorably with those of traditional inorganic corrosion-resistant coatings, suc...