Showing papers on "Corrosion published in 1993"
TL;DR: In this paper, the processes of passive oxidation, deposit-induced corrosion, active oxidation, scale/substance interactions, and scale volatility are studied in the case of high-purity SiC and Si3N4 in pure oxygen, giving attention to such secondary elements in the ceramics as water and CO2 oxidants, combustion environment impurities, and thermal cycling.
Abstract: The processes of passive oxidation, deposit-induced corrosion, active oxidation, scale/substance interactions, and scale volatility are presently studied in the case of high-purity SiC and Si3N4 in pure oxygen, giving attention to such secondary elements in the ceramics as water and CO2 oxidants, combustion environment impurities, and thermal cycling. Deposit-induced corrosion is discussed for the cases of NaSO4 as well as vanadate and oxide-slag deposits; issues associated with the active-to-passive oxidation transition are noted.
709 citations
TL;DR: Magnesium alloys have high strength/weight ratios, but poor corrosion resistance affects the viability of increased magnesium usage in aerospace and other applications as discussed by the authors, and this review approaches the p...
Abstract: Magnesium alloys have high strength/weight ratios, but poor corrosion resistance affects the viability of increased magnesium usage in aerospace and other applications. This review approaches the p...
700 citations
TL;DR: In this article, some preliminary experiments are reported in which small reinforced beams are artificially corroded by an impressed current, and the amount of current and loss of bar cross-section needed to induce the crack at the surface are monitored, together with the evolution of crack width, by the use of strain gauges applied to the surface of the specimens.
Abstract: The appraisal of concrete structures suffering rebar corrosion is one of the most urgent needs regarding the selection of the technical and economical optimum time for repair. Up to now this appraisal has been mainly based on empirical and subjective considerations. Among the different distressing consequences of rebar corrosion the best known is the cracking of concrete cover. However, very few data have been reported in the literature on the amount of corrosion needed to induce this cracking. In the present paper, some preliminary experiments are reported in which small reinforced beams are artificially corroded by an impressed current, and the amount of current (and loss of bar cross-section) needed to induce the crack at the surface are monitored, together with the evolution of crack width, by the use of strain gauges applied to the surface of the specimens. In a companion paper, a numerical model to relate the decrease in rebar cross-section to the cover cracking will be developed. That model is based on the orderly imposition of corrosion to finite elements of the rebar by a fictitious temperature increment that produces analogous effects, while concrete cracking is introduced by a standard smeared-crack model. The experimental results indicate that only a few micrometres of loss in rebar cross-section are needed to induce visible cover cracks (0.1 mm width) in the conditions of the test.
624 citations
TL;DR: It is hypothesized that the restricted crevice environment, coupled with high cyclic stresses which cause repeated fracture of the passive oxide films in the taper, result in an unstable electrochemical environment within the crevice for both the cobalt alloy and Ti-alloy passive films.
Abstract: One hundred forty-eight retrieved modular hip prostheses of both mixed (Ti-6Al-4V/Co-Cr) and similar (Co-Cr/Co-Cr) metal combinations were examined and positive evidence of corrosive attack was found in the conical taper region between head and stem. Significant corrosion was observed in both mixed and similar metal combinations with 16% of necks and 35% of heads (for mixed-metal cases), and 14% of necks and 23% of heads (for similar-metal cases) showing moderate to severe corrosive attack. There was a significant correlation between the percentage of prostheses with moderate to severe corrosion and the duration of implantation for both mixed and similar metal cases, indicating that this corrosion process is progressive in time. Moderate to severe corrosion was seen as early as 2.5 and 11 months (mixed and similar metals, respectively). Scanning electron microscopy and x-ray analysis identified several forms of corrosive attack in the cobalt-based component of the taper. These included, for both mixed and same metal combinations: preferential dissolution of cobalt, fretting, and pitting; mixed metals only: the formation of a Ti-Cr-Mo interfacial phase and interdendritic corrosion; and for similar metals: intergranular attack adjacent to grain boundaries enriched in molybdenum and silicon. It is hypothesized that the restricted crevice environment, coupled with high cyclic stresses which cause repeated fracture of the passive oxide films in the taper, result in an unstable electrochemical environment within the crevice for both the cobalt alloy and Ti-alloy passive films. The passivity of these alloys is subsequently lost and active attack of the taper results. Also, the repeated fracturing of the passive films will result in large amounts of corrosion products being formed. This corrosion and particulate accumulation could result in loss of mechanical integrity of the implants in vivo, create particles for third body wear, and release particles into the surrounding tissues.
584 citations
TL;DR: In this article, a numerical model based on standard finite-element techniques is proposed for the simulation of cracking in concrete specimens when subjected to corrosion of their reinforcement, which is applied to four examples, which were simultaneously tested experimentally and reported in Part 1 of this paper.
Abstract: A numerical model based on standard finite-element techniques is proposed for the simulation of cracking in concrete specimens when subjected to corrosion of their reinforcement. A smeared-crack approach is used to model the behaviour of the concrete finite elements, while the corrosion, which is understood as the applied load on the structure, is modelled by a combination of initial strains and change of elastic properties, which are respectively equivalent to the expansion and softening of the steel elements at the rebar surface when they rust. The model is applied to four examples, which were simultaneously tested experimentally and reported in Part 1 of this paper, and the influence of the main parameters of the model in the response is studied separately. In particular, the effect on the crack-width rate of the specific volume of the rust being formed is quantitatively assessed.
432 citations
TL;DR: In this paper, the nucleation and growth of corrosion pits on stainless steels in chloride is described, and the transition from metastability to stability is described by the pit stability product.
356 citations
TL;DR: The surface modification of AISI 316 stainless steel by plasma immersion ion implantation (PI3) has been investigated over a range of treatment temperatures as discussed by the authors, and the results are similar to those obtained by conventional ion beam implantation of nitrogen, but the depth of nitrogen penetration increases dramatically with temperature.
Abstract: The surface modification of AISI 316 stainless steel by plasma immersion ion implantation (PI3) has been investigated over a range of treatment temperatures. Below 250°C the results are similar to those obtained by conventional ion beam implantation of nitrogen, but the depth of nitrogen penetration increases dramatically with temperature. Up to 450 °C a nitrogen-expanded austenite phase is formed which is shown to have improved corrosion performance over the untreated material. At 520 °C chromium nitride is precipated and the expanded austenite transforms to martensite, leading to a reduction in corrosion resistance. Pin-on-disc testing indicates improved wear resistance at all temperatures, with reduction in the wear volume by factors of several hundred at high loads. This can be attributed to the formation of an oxide layer which prevents the initiation of severe metallic wear.
230 citations
TL;DR: In this paper, a review examines the range of zinc alloy electrodeposited coatings that are available as finishes for continuous steel strip and also possible replacements for electroplated cadmium.
204 citations
TL;DR: Polarization and impedance measurements were performed to study the corrosion behavior of aluminium in acidic and nearly neutral solutions as mentioned in this paper. And the impedance diagram shows at least three time constants or semi-circles of which the size are dependent on the electrode potential.
200 citations
TL;DR: In this article, the Larson index has been shown to be associated with pitting corrosion, which appears to interfere with disinfection more than general corrosion, and the type of corrosion influences the efficiency of disinfection of the biofilm.
Abstract: Previous research has shown a relationship between corrosion of an iron pipe and the protection of biofilm bacteria from disinfection. It is believed that the corrosion product reacts with chlorine disinfectants and prevents the biocide from penetrating the biofilm layer and inactivating the attached bacteria. The results of the current study show that even low levels of corrosion, i.e., <1 mpy, could interfere with free chlorine disinfection. High corrosion rates affected monochloramine disinfection. The research also suggested that the type of corrosion influences the efficiency of disinfection of the biofilm. Increases in the ratio of chloride and sulfate to bicarbonate (the Larson index) have been shown to be associated with pitting corrosion, which appears to interfere with disinfection more than general corrosion
TL;DR: In this paper, atmospheric corrosion and environmental data, compiled in a comprehensive literature survey were statistically processed for establishing general corrosion damage functions for mild steel, zinc, copper and aluminium, in terms of simple meteorological and pollution parameters.
TL;DR: In this article, the dissolution of MnS inclusions in stainless steel exposed in 0.5 M NaCl + 0.08% H 2 O 2 at the free corrosion potential for 10 s has been studied using simultaneous Auger/EDX analysis and imaging and electron microscopy.
TL;DR: In this paper, the authors simulated metal dusting in CO-H2H2O atmospheres at 650°C and showed that the unstable carbide M3C is an intermediate, which decomposes according to M 3C = 3M + C, the metal particles serving as catalysts for further coke deposition.
TL;DR: In this paper, a study of corrosion products formed in bars embedded in concrete and bare bars exposed in a marine environment over a period of 5 years was conducted, and it was found that crystalline magnetite, goethite and lepidocrocite made up only 30% of the rust formed within concrete, as compared to about 45% for uncovered bars.
TL;DR: In this paper, simple equivalent circuits (ECs) for the impedance behavior of polymer coated steel and anodized Al alloys and Al-based metal matrix composites are discussed.
TL;DR: In this paper, the authors studied the corrosion of mild steel under completely anaerobic conditions in the presence of a mixed population biofilm, including sulfate-reducing bacteria (SRB), in a continuous flow system.
Abstract: Corrosion of mild steel under completely anaerobic conditions in the presence of a mixed population biofilm, including sulfate-reducing bacteria (SRB), has been studied in a continuous flow system. The closed channel flow reactor was continuously fed with low concentration substrate at different dilution rates that influenced biofilm accumulation. No direct correlation was observed between corrosion and SRB activity in the absence of ferrous iron. Furthermore, corrosion of mild steel in the SRB environment was determined by the nature of the metal and environmental conditions such as dissolved iron concentration. When formation of an iron sulfide film on mild steel was prevented before the biofilm accumulated, the metal surface retained its scratch lines after a 21-day experiment (SRB at 2.6 × 109/cm2). However, when the iron sulfide film was formed before the accumulation of biofilm, visible localized corrosion appeared after 14 days and increased up to 21 days. Intergranular and pitting attack ...
TL;DR: In this paper, a new method of surface modification by electrical discharge machining using composite structured electrode surface modifications on work pieces of carbon steel or aluminum were carried out in hydrocarbon oil using composite electrodes Composite electrode consists of green compact products or sintered products Copper, aluminum, tungsten carbide and titanium were used for the material of the electrode, it was revealed that there existed the electrode material in the work surface layer and the characteristics of the surface of raw material remarkably changed
TL;DR: In the field, concrete often has cracks that extend to the reinforcing steel as discussed by the authors, which is typically in uncracked concrete, but concrete can also have cracks in steel reinforcing steel.
Abstract: Corrosion of steel in concrete is studied typically in uncracked concrete. In the field, however, concrete often has cracks that extend to the reinforcing steel. Electrochemical corrosion ...
TL;DR: In this article, the electrochemical properties of three intermetallic phases (Al 2 Cu, β-Al 3 Ta and Al 3 Zr) were compared to high purity Al in inert buffer solutions and dilute halide solutions.
TL;DR: In this article, a bending cantilever beam technique was used to measure tensile stress at the metal/oxide interface due to the volume difference between the metal ionized and the oxide formed at that interface.
TL;DR: In this paper, a cast nickel-aluminium bronze was measured in synthetic seawater and sodium chloride solution and the process of layer formation under flow conditions was studied and the reaction kinetics in freshly prepared condition and in the passive state was evaluated under well defined hydrodynamic conditions using a rotating disc electrode.
TL;DR: In this article, the effect of various functional groups in N- and S-containing inhibitors on the corrosion activity of iron and steel in neutral and acid media was investigated and different experimental methods were applied.
Patent•
14 Oct 1993
TL;DR: In this article, a vapor phase corrosion inhibitor-desiccant composite comprising silica gel granules coated with a component is selected from a formulation comprising anhydrous molybdates such as ammonium dimolybdate, sodium molyb date, mixed with benzotriazole and sodium nitrate.
Abstract: A vapor phase corrosion inhibitor-desiccant composite comprising silica gel granules coated with a vapor phase corrosion inhibitor component. The corrosion inhibitor component is selected from a formulation comprising anhydrous molybdates such as ammonium dimolybdate, sodium molybdate and amine molybdates mixed with benzotriazole and sodium nitrate, or from a formulation comprising amine benzoates, amine nitrates and benzotriazole. The composites can be impregnated into foam, extruded with polyolefin films which can additionally be laminated with metallized second film, or encapsulated in an air-permeable container. The corrosion inhibitor formulations have vapor pressures which provide ongoing corrosion protection for susceptible articles situated favorably with respect to the composite.
TL;DR: In this article, a direct current polarization (DCP) was used to degrade carbon steel components in sulfur-containing environments, which is a major concern in oil and gas production, and the results showed that the DCP was effective in reducing carbon steel degradation.
Abstract: The chemical degradation of carbon steel components in sulfur-containing environments is a major concern in oil and gas production. In a previous study, a direct current (DC) polarization ...
TL;DR: The results indicated that Zircaloy-2, Ti-5% Ta and thermally-oxidised Ti showed excellent corrosion resistance also in a simulated uranium-containing reprocessing medium in a concentrated nitric acid solution.
TL;DR: The relationship of laboratory fluid flow corrosion test techniques to flow-accelerated corrosion in field applications and the parameters required to apply laboratory data effectively in the field were studied in this paper, where single-phase, aqueous, sweet corrosion of steel in turbulent pipe flow (12.7 mm and 25.4 mm diam) was correlated to corrosion in jet impingement and rotating cylinder tests.
Abstract: The relationship of laboratory fluid flow corrosion test techniques to flow-accelerated corrosion in field applications and the parameters required to apply laboratory data effectively in the field were studied. Single-phase, aqueous, sweet corrosion of steel in turbulent pipe flow (12.7 mm and 25.4 mm diam) was correlated to corrosion in jet impingement and rotating cylinder tests. All tests were conducted simultaneously, using the same test fluid to minimize environmental variables and to allow a direct, realistic comparison of test methods. Rotating cylinder electrode corrosion rates did not correlate with pipe flow based on wall shear stress or mass transfer for flow-accelerated corrosion of carbon (C) steel in the environment studied. Jet impingement corrosion rates for the test ring at r/r0=3 correlated with pipe flow based on wall shear stress. The general equation for flow-accelerated corrosion of C steel under turbulent flow conditions in this environment was expressed as: Rcorr = a τwb ...
TL;DR: In this article, the passive behaviour of pure Mg at 25°C was studied by electrochemical methods in solutions of pH 7−14 containing 0−4 M KF and the dependences of the quasi-steady corrosion current density on pH and [KF were assessed.
TL;DR: In this paper, the effects of grain size and phosphorous content on the corrosion characteristics of nanocrystalline Ni-P alloys tested in 0.1M H 2 SO 4 by anodic polarization is evaluated and compared with the corrosion behavior of amorphous Ni-p and high purity conventional polycrystallineNi.
TL;DR: In this paper, the anodic behavior of the major pure metals of which stainless steels are composed has been studied in chloride-containing aqueous solutions at neutral and acidic pH values, both before and after a nitriding treatment.