Showing papers on "Corrosion published in 1990"
TL;DR: In this article, the influence of surface inhomogeneities on corrosion processes is demonstrated by electrochemical impedance spectroscopy (EIS), and experimental impedance data obtained in different systems are discussed on the basis of transfer function analysis.
648 citations
462 citations
TL;DR: In this article, the authors used a Kelvin probe as a reference electrode for the measurement of electrode potentials and showed that the potential drop across the oxide scale formed on top of the iron surface is small if the surface is kept in a humid environment (e.g. 95% relative humidity).
450 citations
TL;DR: The need for these materials has to do with corrosion as discussed by the authors and at elevated temperatures, high temperature corrosion reactions occur at an alarming rate in unprotected materials or conventional materials such as carbon steel.
Abstract: The need for these materials has to do with corrosion. At elevated temperatures, high temperature corrosion reactions occur at an alarming rate in unprotected materials or conventional materials such as carbon steel. To reduce the occurrence of oxidation, and other corrosion processes such as carburization, sulfidation, halogen corrosion, salt corrosion and hot corrosion, engineers continue to develop materials that can withstand extreme temperatures, without compromising mechanical properties.
410 citations
TL;DR: In this paper, the application of EIS as a new tool for the investigation of methods of corrosion protection is illustrated for corrosion inhibitors, conversion coatings, polymer coatings and oxide layers as well as for cathodic protection of stainless steels.
378 citations
TL;DR: In this paper, the corrosion rate of binary rapidly solidified (RS) magnesium alloys was examined using electrochemical techniques, and it was shown that aluminum was the only element which caused a decrease in the corrosion ratio of magnesium; the corrosion rates decreased with increasing aluminum content.
Abstract: Effects of alloying elements on the corrosion resistance of mostly binary rapidly solidified (RS) magnesium alloys were examined using electrochemical techniques. Uniform corrosion rates were measured at room temperature in a pH 9.2 sodium borate buffer using electrochemical impedance spectroscopy (EIS). Comparisons of electrochemically and gravimetrically determined corrosion rates of bulk magnesium and magnesium alloys showed that the charge transfer resistance could be used to accurately measure the corrosion rates of these materials provided the attack was indeed uniform. The correlation broke down for pure magnesium, which suffered a nonuniform attack due to the undermining of small particles. Corrosion rate measurements of binary alloys showed that aluminum was the only element which caused a decrease in the corrosion rate of magnesium; the corrosion rate decreased with increasing aluminum content. Low concentrations of zinc and lithium resulted in alloys with corrosion rates slightly higher than that of the pure magnesium. Anodic polarization scans were used to compare as‐cast and rapidly solidified commercial ternary alloy AZ61 in borate (pH 9.2) and carbonate/bicarbonate (pH 10.0) buffer solutions containing 100 ppm, 1000 ppm, and 3.5 weight percent sodium chloride. The RS AZ61 formed a more protective film than the cast material under these conditions.
320 citations
Book•
01 Dec 1990
TL;DR: A comprehensive treatment of all forms of high temperature corrosion problems encountered in industry, especially gas turbine and aerospace, heat treating, mineral and metallurgical processing, ceramic, electronic and glass manufacturing, automotive pulp and paper waste incineration fossil fuel power generation coal gasification nuclear, is described in this article.
Abstract: This extensive materials selection and application book is the first of its kind. It describes a comprehensive treatment of all forms of high temperature corrosion problems encountered in industry, especially gas turbine and aerospace, heat treating, mineral and metallurgical processing, ceramic, electronic and glass manufacturing, automotive pulp and paper waste incineration fossil fuel power generation coal gasification nuclear. Materials problems discussed include those due to oxidation, carburization and metal dusting nitridation, halogen corrosion, sulfidation, ash/salt deposit corrosion (e.g. hot corrosion, fuel ash corrosion, etc.), molten salt corrosion and molten metal corrosion. This single source contains an exhaustive corrosion database with a total of 101 tables and 169 figures, eliminating the need for conducting a time-consuming literature search. This book is a must for solving high temperature corrosion problems and learning about corrosion reactions of various high temperature corrosion modes. Contents: Methods of Testing and Evaluation Oxidation Carburization and Metal Dusting Nitridation Corrosion by Halogen Sulfidation Ash/Salt Deposit Corrosion - Molten Salt Corrosion Molten Metal Corrosion.
319 citations
TL;DR: In this article, the shape memory effect (SME) of Fe-Mn-Si alloys is investigated and the effects of alloying additions on the SME of these alloys are reported.
Abstract: Fe-Mn-Si alloys are shape memory alloys which make use of the γ→e stress-induced martensitic transformation. In this study, we report the effects of alloying additions on the shape memory effect (SME) of these alloys. It was found that the Ms temperature, the Neel temperature (TN) and the volume of stress-induced martensite govern the SME. Through the optimization of these factors we found that new alloy systems such as Fe-28Mn-6Si-5Cr, Fe-20Mn-5Si-8Cr-5Ni and Fe-16Mn-5Si-12Cr-5Ni alloys could exhibit good SME along with good corrosion resistance. And it was also found that the thermomechanical treatment which improved the SME in Fe-Mn-Si base system was also effective to improve the SME of these new systems.
305 citations
TL;DR: In this paper, the corrosion properties of pure iron and the alloys Fe-0.5Cu and Fe-3.4Cu are investigated during several wet/dry transitions, and the corrosion potential is measured with a Kelvin probe without touching the surface under investigation.
298 citations
TL;DR: In this article, the applicability of the CSL/DSC model of interface structure to intergranular corrosion susceptibility at grain boundaries in high purity (99.999%) polycrystalline nickel was evaluated.
Abstract: Electrochemical studies were conducted in 2 N H2SO4 at 303 K in order to assess the applicability of the CSL/DSC model of interface structure to intergranular corrosion susceptibility at grain boundaries in high purity (99.999%) polycrystalline nickel. Susceptibility to the initiation of localized corrosion at grain boundaries was manifested through characteristic overpotentials for passive film breakdown. These characteristic overpotentials were found to (1) decrease with increasing bulk sulphur concentration (0.3–50 ppm), and (2) be strongly dependent on interface structure (CSL/DSC). Boundaries close (Δθ) to low ΣCSL relationships were observed to be most resistant to the initiation of localized corrosion. A limiting structural field was determined, not extending beyond Σ25, and restricted to an angular deviation limit defined by a relation of the type: Δθ = 15° Σ−5/6. Results were determined to be consistent with a mechanism whereby susceptibility to intergranular corrosion is dictated by the (1) geometry, and (2) chemistry (i.e. solute concentration) of intrinsic grain boundary dislocations.
246 citations
TL;DR: In this paper, a circuit was presented which allows the measurement of polarisation curves on metal surfaces which are covered by electrolyte layers as thin as 2 μm, and the circuit does not need any Luggin capillary but uses a Kelvin probe as a reference electrode which does not touch the surface under investigation.
Journal Article•
TL;DR: In this paper, the main steps leading to the technique of scanning electron microscopy (SEM) of vascular corrosion casts are discussed and a detailed discussion of the physical and chemical properties of the casting media and their significance for polymerization, shrinkage, casting quality, corrosion resistance, and thermal and spatial stability is given.
Abstract: The present paper states very briefly the main steps leading to the technique of scanning electron microscopy (SEM) of vascular corrosion casts. From the terms presently used (injection method, microcorrosion cast, injection replica, vascular corrosion cast, vascular cast) the use of "vascular corrosion cast" for lymphatic and blood vessels is recommended. Specification and pretreatment (kind, volume, dosage of anticoagulants, vasoactive substances and spasmolytica used) of the animals examined are referenced as they are available from the literature. The recommendation is given to pay more attention to these parameters than done so far. The steps necessary for producing reasonable and suitable vascular corrosion casts are critically described. Special attention is paid to the physical and chemical properties of the casting media and their significance for polymerization, shrinkage, casting quality, corrosion resistance, and thermal and spatial stability. Emphasis is also focused on the advantages of cutting the vascular corrosion casts embedded in an ice block by a band saw, a self constructed multi-blade cutting device or a mini wheel-saw placed in the chamber of a cryomicrotome. From the drying methods presently used freeze-drying is stressed because of minimal specimen damage. To render casts conductive in most cases sputter-coating is sufficient. It is recommended to run the SEM with 5-10 kV since the resolution received still reveals all details the casting media presently can replicate. Further the application of scanning electron microscopy of vascular corrosion casts in fully differentiated normal tissue, in pathologic tissue as well as in developing tissues and organs is stated. Lastly possibilities and conditions are discussed under which SEM of vascular corrosion casts can serve to quantify vascular structures in order to make the technique more than pure descriptive.
TL;DR: In this paper, the electrochemical behavior of magnesium in aerated 0.5 M Na 2 SO 4 solution was investigated by plotting steadystate current and measuring electrochemical impedance, and the results were in agreement with those obtained by direct assay of dissolved magnesium by atomic absorption spectroscopy.
TL;DR: In this article, a review is made of essential subjects on the passivtion process, the passive film, and the film breakdown, which is followed either by repassivation or by pitting corrosion depending on the degree of metal salt enrichment at the break sites.
TL;DR: In this article, the effect of components Fe, Mn, and Si on the electrochemical behavior of phases Al 3 Fe, αAl(Fe, Mn)Si, and δAlFeSi were investigated in NaOH solutions.
Abstract: The effect of components Fe, Mn, and Si on the electrochemical behavior of phases Al 3 Fe, αAl(Fe, Mn)Si, and δAlFeSi were investigated in NaOH solutions. Anodic polarization of the phases leads, under certain conditions, to an enrichment of the surface with the more noble components. Enrichment with Fe is detrimental to cathodic behavior. The added presence of Mn or Si in the phase reduced the effect of Fe on both the anodic and cathodic reaction rates. The mechanisms are discussed briefly along with the significance of these phenomena on the localized corrosion of aluminum alloys
TL;DR: In this article, the authors applied electrochemical impedance techniques to the study of aluminium corrosion in hydrochloric acid solution in the passive region and obtained impedance spectra in stationary solution and in solution moving due to electrode rotation.
Abstract: Electrochemical impedance techniques are applied to the study of aluminium corrosion in hydrochloric acid solution in the passive region. Impedance spectra are obtained in stationary solution and in solution moving due to electrode rotation. The form of the spectra shows the importance of multistep dissolution, ionic migration through the oxide layer, relaxation effects and the influence of chloride ion.
TL;DR: In this article, the interdependence between these bulk chemical parameters and mean corrosion intensity (μa. cm−2) values have been found, and the variation of instantenous corrosion intensity in time has been followed by the electrochemical technique of Resistance Polarization (Rp).
TL;DR: In this paper, the corrosion of mild steel in sulfuric acid containing 4 × 10−4 M of either D-galactose thiosemicarbazone, 1-phenyl THIosemicarazide, or 4-phosphoric acid was studied.
Abstract: The corrosion of mild steel in sulfuric acid containing 4 × 10−4 M of either D-galactose thiosemicarbazone, 1-phenyl thiosemicarbazide, or 4-phenyl thiosemicarbazide, has been studied over...
01 Jan 1990
TL;DR: In this article, the authors treat pitting corrosion as a time-dependent stochastic damage process characterized by an exponential or logarithmic pit growth, and treat it as a deterministic process.
Abstract: Pitting corrosion is treated as a time-dependent stochastic damage process characterized by an exponential or logarithmic pit growth. Data from water injection pipeline systems and from th...
TL;DR: In this article, the pitting and intergranular corrosion behavior of AA 2090 (Al-2Li-3Cu, UNS A92090) in a 3.5 wt% NaCl solution was investigated.
Abstract: The pitting and intergranular corrosion behavior of alloy AA 2090 (Al-2Li-3Cu, UNS A92090) in a 3.5 wt% NaCl solution was investigated. Techniques used included potentiodynamic polarization, galvanic couples, and pH measurements in simulated crevices. Polarization scans were performed on under-aged and peak-aged material to obtain the standard polarization parameters. Corroded specimens were examined with optical microscopy, scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDAX) to distinguish various local corrosion morphologies. Ingots were cast to approximate the subgrain boundary, T1 (Al2CuLi) phase, and Al-Cu-Fe constituent phases inherent in the alloy. These were then galvanically coupled to solution heat treated (SHT) 2090 to identify their role in local corrosion processes. Simulated crevices were produced by inserting pH micro-electrodes into crevices machined in 2090 blocks to measure pH versus time response in occluded environments. Based on the experiments...
01 Jan 1990
TL;DR: In this article, surface nitrides were generated electrochemically at room temperature on the surface of high purity samples of Cr, Mo, Fe and Ni and on the surfaces of types 304, 317LX, 904L and AL6X stainless steels.
TL;DR: X-ray diffraction analysis of the surface of pure titanium revealed that the relative peak intensity of alpha-Ti decreased and that of TiO2 increased, with increasing firing temperature, and the Vickers hardness number of titanium increased with temperature especially over 900 degrees C, and was harder in air than in vacuum.
Abstract: Titanium is strong, resists corrosion and has a low density and excellent biocompatibility. Conventional ceramic-metal restorations have been extensively used in dentistry because of their esthetic appearance and good mechanical properties. This study investigates oxidation effects on the porcelain-titanium interface reactions and bond strength. Pure titanium was treated in a porcelain furnace at temperatures of 600 to 1000°C under either vacuum or air. X-ray diffraction analysis of the surface of pure titanium revealed that the relative peak intensity of α-Ti decreased and that of TiO2 increased, with increasing firing temperature. The Vickers hardness number of titanium increased with temperature especially over 900°C, and was harder in air than in vacuum. The tension-shear bond strength of the porcelain-titanium system was the highest in the green stage and lowest after 900°C treatment. Metallographic microscopy of the porcelain-titanium interface revealed a thick band-like zone in the sample treated over 900°C. The excess thick layer of TiO2 apparently weakened the bond strength of porcelain-titanium. Unlike the conventional ceramic-gold alloy system the recommended degassing procedure was not suitable for porcelain-pure titanium restoration.
TL;DR: The role of inclusions as initiators of pitting corrosion has been studied from the very inception of attack in stainless steel 316 relative to the bulk composition as mentioned in this paper, and it is suggested from this investigation that corrosive attack starts on MnS inclusions or on small MnS precipitates associated with oxide inclusions.
TL;DR: In this paper, a review of the chemical processes involved in the atmospheric corrosion of iron and its alloys is presented, with information on iron-containing minerals and other crystalline structures that are likely to be present.
Abstract: Despite extensive study over the years, the chemical processes involved in the atmospheric corrosion of iron and its alloys remain poorly understood. Most conceptual studies have ignored the chemical influence of the trace anions (Cl−,, , , etc.) present in the atmosphere and in precipitation. This review, presented from the perspective of atmospheric chemistry and mineralogy, provides an analysis of rust layer formation, evolution, morphology, and composition, together with information on iron‐containing minerals and other crystalline structures that are likely to be present. The chemical reactions involved in the formation of these constituents during the corrosion process are then presented. The reactions are not spatially homogeneous, but favor pits, voids, and crevices in the metal surface. It is demonstrated that (i) the pH of the moisture on the surface is crucial to the corrosion process, since it controls the dissolution of the passive oxyhydroxide surface; the pH is largely controlled by atmospheric and dissolved in the moisture or by fog or rain deposited on the surface; (ii) the extant data suggest that the rate of iron oxyhydroxide formation is slow; hence, the presence of reactive anions generally results in their blending into mixed hydroxy‐anion products; (iii) the interactive chemistry of readily available hydrogen peroxide and bisulfite ion in the aqueous surface film can either enhance or impede the rate of corrosion; (iv) photon‐driven reactions can promote the corrosion of iron and its alloys. This analysis unifies the analytical information, as well as the data on kinetic processes, and provides the basis for a full understanding of the atmospheric corrosion of iron and low alloy steels.
TL;DR: The classic corrosion reaction is electrochemical, resulting in the dissolution of metal from anodic sites with subsequent electron acceptance at cathodic sites Consumption of electrons varies, depending on the redox potential of the surface.
Abstract: Corrosion reactions may be induced or enhanced by microbial activity The classic corrosion reaction is electrochemical, resulting in the dissolution of metal from anodic sites with subsequent electron acceptance at cathodic sites Consumption of electrons varies, depending on the redox potential of the surface In an aerobic environment, oxygen is the electron acceptor, forming metal oxides and hydroxides At low redox potentials, protons become the electron acceptors, yielding hydrogen gas and other highly reduced products The process of corrosion is accelerated by removal of the end products of the chemical reactions
TL;DR: A review of fatigue behavior of magnesium alloys can be found in the available literature from 1 923 to the present as mentioned in this paper, which should help researchers in deciding the course of future investigation and designers in locating necessary data.
Abstract: This paper represents a review of fatigue behavior of magnesium (Mg) alloys found in the available literature from 1 923 to the present. It should help researchers in deciding the course of future investigation and designers in locating necessary data. Mg is increasing in use (I). Due to comparable strength and price, but lower density, its alloys are replacing aluminum alloys as construction materials in many applications. Corrosion resistance of Mg alloys today is a less serious problem because of better control of alloying element contents (2), and their corrosion resistance is comparable to that of low strength steels ( 1 ). Elevated temperature applications of Mg alloys are possible up to 370°C ( 1 ). The literature on Mg alloys fatigue behavior is incomplete, covering only specific topics for some Mg alloys. Examples of stress-life (S-N) curves are found for many alloys, but strain-life (s-N) curves are very rare. The number of references dealing with fatiguc crack growth (da/dN -11K) behavior falls between these two. It should be noted that most S-N data found are rather old, dating from the 1 930s to 1 960s and are widely reproduced in many publications. Fatigue crack growth behavior data, however, are more recent, dating from the 1970s to the present day. The fatigue properties of only Mg alloys are considered here (4--11). Mg metal matrix composites, although very promising materials, were beyond the scope of this paper. The ASTM standard system of nomenclature for nonferrous alloys,
TL;DR: In this article, the authors investigated the characteristics of aqueous dissolution of three complex silicate glasses (rhyolitic, basaltic, and simulated nuclear-waste glass) by analytical techniques based on energetic ion beams, which provided depth profiles of various elements including hydrogen, on the altered surface of the materials.