Showing papers on "Corrosion published in 1977"
TL;DR: In this article, six typical problem areas requiring improved understanding of glass surfaces are identified, including corrosion mechanisms, mixed-alkali effect, surface passivation with solution ions, protective film formation, role of CaO, R 2 O/SiO 2 and Al 2 O 3 in glass corrosion, glass surface area to solution volume ratio, relevance of autoclave procedures in durability tests, and bioglass-bone bonding mechanisms.
Abstract: Six typical problem areas requiring improved understanding of glass surfaces are identified. Results obtained from several surface-analysis instruments show that five types of surfaces are characteristic of a silicate glass at any time in its history. The type of surface is dependent on the environmental history of the glass and may be defined in terms of surface compositional profiles. Several important glass surface topics of current interest are discussed. These include: corrosion mechanisms; mixed-alkali effect; surface passivation with solution ions; protective film formation; the role of CaO, R 2 O/SiO 2 and Al 2 O 3 in glass corrosion; glass surface area to solution volume ratio; relevance of autoclave procedures in durability tests; and bioglass-bone bonding mechanisms.
409 citations
TL;DR: In this article, the compositions of the alloy surface and the surface oxide on mechanically polished iron-chromium alloys were studied using the XPS technique, and the results showed no enrichment of chromium or iron either in the oxide layer or the Alloy surface.
327 citations
TL;DR: In this paper, it has been shown that the long-term chemical resistance of a glass is mainly determined by the thermodynamic activity and stability of its component oxides in aqueous solutions.
Abstract: The various hypotheses regarding corrosion of oxide glass surface by aqueous solutions have been reviewed. It has been shown that the long-term chemical resistance of a glass is mainly determined by the thermodynamic activity and stability of its component oxides in aqueous solutions. The stability of different oxides commonly used in glass-making like SiO2, ZnO, PbO, Al2O3, ZrO2 etc. in aqueous solutions of different pH has been calculated with available thermodynamic data, and these have been discussed in relation to the corrosion behaviour of glasses (prepared with these oxides) in aqueous solutions of various pH range. Suitable experimental results have been furnished to justify the importance of thermodynamic stability of component oxides of a glass on its corrosion behaviour in aqueous solutions.
307 citations
TL;DR: In this article, the role of the metal/metal oxide or the lower metal oxide/higher metal oxide couple in determining the minimum voltage required for the evolution of oxygen is emphasized, together with other essential requirements such as electrical resistivity, electrode microstructure, corrosion resistance and catalytic properties.
207 citations
TL;DR: It appears that, by using this new combination of materials for the socket and the ball, it will be possible to prolong the service life of artificial hip joints considerably without having effecy any fundamental changes in the present design and implantation principle.
Abstract: Investigations over the years have shown that the mirror-finished Al2O3 ceramic is a much more suitable frictional counterpart to ultrahigh molecular weight (UHMW) polyethylene than metal. Despite the extremely gread hardness difference between polyethylene and Al2O3 ceramic, a considerable lower wear rate is obtained for the polyethylene socked with this new low-friction material combination. The unexpectedly favorable tribological behavior of this ceramic material in contact with polyethylene may be attributed to the following factors: better values for corrosion resistance characteristics, wettability with liquids, surfact gloss, hardness, and scratch resistance of the ceramic material in comparison with those of the hitherto used metallic implant materials (AISI-316L steel or cast Co-Cr-Mo alloy). It appears that, by using this new combination of materials for the socket and the ball, it will be possible to prolong the service life of artificial hip joints considerably without having effecy any fundamental changes in the present design and implantation principle retaining the hitherto used anchorage shaft made of wrought Co-Ni-Cr-Mo-Ti alloy Protasul-10 of extremely high corrosion fatigue strength.
186 citations
TL;DR: In this article, the effect of solute content on the pitting potential of Al-Cu alloys in 1M NaCl solutions was studied, and it was found that the maximum pitting value was limited by the solubility of Cu in the Al.
170 citations
TL;DR: In this article, the negative difference effect was found to be a direct result of the breakdown of passive passivity of magnesium, which is a naturally passive metal that undergoes pitting corrosion when exposed to chloride ions in non-oxidizing solutions.
154 citations
TL;DR: In this article, the surface composition of unstabilized austenitic stainless steel (En 58A) was determined by Auger electron spectroscopy and measurements carried out when oxidation was complete were made using energy dispersive X-ray analysis and electron microprobe analysis.
150 citations
TL;DR: In this paper, hot corrosion is defined as a form of accelerated oxidation of alloys which can occur in combustion gases in the presence of impurities, and the characteristics of the reaction are defined by describing practical examples, and then the results of a variety of laboratory experiments are considered in relation to the practical process.
Abstract: : Hot corrosion is a form of accelerated oxidation of alloys which can occur in combustion gases in the presence of impurities. The characteristics of the reaction are defined by describing practical examples, and then the results of a variety of laboratory experiments are considered in relation to the practical process. The temperature dependence and kinetics of the corrosion are briefly presented, and the effect of alloying elements is discussed; high chromium contents are required for good corrosion resistance, but there is no general agreement on the effect of other alloy elements. A number of mechanisms for hot corrosion are described and discussed in relation to the practical results.
120 citations
99 citations
TL;DR: In this article, the Corrosion and Oxidation of Metals, the authors present an approach to the problem of metal degradation and propose a method to solve it, which is referred to as "corrosion-oxidation of metals".
Abstract: (1977). The Corrosion and Oxidation of Metals. British Corrosion Journal: Vol. 12, No. 1, pp. 5-5.
TL;DR: In this paper, a series of experimental austenitic stainless steels with varying chromium, molybdenum and nitrogen contents have been measured and some gravimetric testing has been carried out on them.
Abstract: Pitting potentials have been measured and some gravimetric testing has been carried out on a series of experimental austenitic stainless steels with varying chromium, molybdenum and nitrogen contents. All three of these elements were found to contribute to the resistance to the initiation of pitting corrosion, and synergistic effects have been noted. The effect of nitrogen is especially potent in a steel with 22% chromium and 3% molybdenum.
TL;DR: In this paper, the preparation of polycrystalline n-type iron oxide electrodes by heating of iron samples in air is reported, and the behavior of these electrodes in aqueous solutions of different pH values in the presence and absence of illumination is shown.
Abstract: The preparation of polycrystalline n-type iron oxide electrodes by heating of iron samples in air is reported. The behavior of these electrodes in aqueous solutions of different pH values in the presence and absence of illumination is shown. The photocurrent response of these electrodes to all wavelengths in the visible region is seen. Photoassisted electrolysis of water occurs at these wavelengths resulting in the evolution of oxygen bubbles at the iron oxide electrodes with no noticeable corrosion problems in pH 40 acetate buffer to 5.5M KOH solutions.
TL;DR: In this article, a theoretical analysis of the magnetic field effect was developed, and its validity established by experiments involving the Ti/H/sub 2/SO/sub 4/ (H /sub 2/-saturated) system.
Abstract: A study was made to determine whether a magnetic field, such as that associated with a thermonuclear reactor, might adversely affect the corrosion behavior of metallic surfaces in contact with a flowing electrolyte. In metal/flowing-electrolyte systems, electrochemical reactions dependent on the metal/electrolyte interfacial potential difference are affected by an applied magnetic field as a consequence of the Lorentz forces acting on the charged components of the flowing electrolyte. A theoretical analysis of the magnetic field effect was developed, and its validity established by experiments involving the Ti/H/sub 2/SO/sub 4/ (H/sub 2/-saturated) system. Quantitative agreement between theoretical and experimental results was obtained for the electrochemical behavior of Ti in 1N H/sub 2/SO/sub 4/ (mean flow velocity: 0 to 650 cm/sec) over the available range of magnetic flux density (0 to 2.1 Tesla). Although the experimental work employed discrete Ti electrodes set in the wall of nonconducting Pyrex glass pipe, the theory was extended to include metallic pipes, i.e., the ''conducting-wall'' case, for which case the ''wall-shorting'' effect was shown to be negligible. In addition to the adverse effect of a magnetic field on the ''uniform'' corrosion behavior of metals, the imposition of a magnetic field can also result in enhanced susceptibilitymore » to stress corrosion cracking, localized (pitting or crevice) corrosion, oxidation and reduction of solution species, and electrochemical decomposition of the electrolyte. The aforementioned processes, to name a few, are all potential dependent and, consequently, subject to the magnetic field effect.« less
TL;DR: In this paper, a technique for testing materials in sea water under velocity conditions has been developed which utilizes fluid dynamics to evaluate the corrosion test results and the data obtained from thi...
Abstract: A technique for testing materials in sea water under velocity conditions has been developed which utilizes fluid dynamics to evaluate the corrosion test results. The data obtained from thi...
TL;DR: In this article, the authors discuss the kinetics of the spontaneous reaction occurring during the formation of a coloured interference film on stainless steel in hot CrO 3 + H 2 SO 4 aqueous solution.
TL;DR: In this article, a pack cementation method is described for forming a hard dense boride coating on ferrous materials, which is characterized by metallography, X-ray diffraction and electron microprobe analysis.
TL;DR: In this paper, the corrosion and hydriding performance of zirconium-base alloys under PWR and BWR conditions, as gaged by a comprehensive review of the technical literature, has been evaluated.
Abstract: The corrosion and hydriding performance of zirconium-base alloys under pressurized water reactor (PWR) and boiling water reactor (BWR) conditions, as gaged by a comprehensive review of the technical literature, has been evaluated. Starting with a brief historical description of the development of zirconium for cladding and structural material in nuclear reactors and the corrosion problems associated with the use of the pure metal, it is shown that the development of zirconium-base alloys proceeded down two major paths. One development involved the zirconium-tin system and led to the development of the Zircaloys, whereas the other concentrated upon zirconium-niobium materials and produced the two major alloys of this system in use today: Zr-1Nb and Zr-2.5Nb. The corrosion data generated for each system, both in and ex-reactor, are evaluated, and the benefits and potential problems associated with each alloy are discussed for both PWR and BWR applications. Potential areas of concern for the Zircaloy alloys in both applications include exposure temperature limitations and the formation of nonuniform accelerated corrosion products in the oxygenated irradiation environment. The zirconium-niobium alloys are found to be very sensitive to oxygen in the coolant and to prior heat treatment in ex-reactor experiments but show either minimum or negativemore » acceleration due to the presence of neutron irradiation. Alloys that combine these two additives (for example, Zr-3Nb-1Sn and Ozhennite-0.5) do not appear to show promise as possible replacements for the Zircaloys under present-day conditions. The lack of a unifying theory for describing the mechanisms involved in the corrosion of zirconium-base alloys may hamper seriously possible future applications under different design conditions.« less
TL;DR: In this paper, a long term immersion testing has been carried out of stressed, austenitic steel samples (304S15) in chloride solutions of varying strength, type, temperature and pH.
TL;DR: In this paper, the effects of underfilm salt contaminants on atmospheric corrosion were investigated, and it was interpreted as a form of anodic undermining corrosion, which involves transport of the anion and its effect on the dissolution of metal from beneath the organic coating.
Abstract: While the ability of the organic coating to conduct corrosion currents may sometimes come into play, primarily the corrosive deterioration of protective organic coatings is brought above by the flow of corrosion currents through a film of electrolyte beneath the organic coating. Any of several specific mechanisms may be involved. The influences of contaminants lie in their abilities to: (1) draw water through the organic coating to establish a conductive film of moisture, (2) provide ions to carry the corrosion currents, and (3) provide ions of specific effect on underfilm corrosion mechanisms. Specific attention is given here to the effects of underfilm salt contaminants on atmospheric corrosion. Filiform corrosion observed is interpreted as a form of anodic undermining corrosion, which involves transport of the anion and the effect of the anion on the dissolution of metal from beneath the organic coating. Cathodic detachment, also observed, is interpreted in terms of cationic transport and the ...
TL;DR: In this article, the requirements of an analytical technique for thin films and examines the present role of XPS in this context are discussed. And the areas covered will include elemental analysis, evaluation of valence state, nondestructive information, elemental distribution and finally the use of ion-etch depth profiling.
TL;DR: In this paper, the free energy of adsorption of n−decylamine on zinc from acidic chloride solution has been studied using the corrosion technique, where the degree of surface coverage was calculated from the corrosion rates.
Abstract: The adsorption of n‐decylamine on zinc from acidic chloride solution has been studied using the corrosion technique. The corrosion rates of zinc in acidic chloride solution containing n‐decylamine are measured as a function of n‐decylamine concentration. The degree of surface coverage as calculated from the corrosion rates is used to calculate the free energy of adsorption of n‐decylamine. The variation of negative free energy of adsorption with surface coverage is interpreted in terms of change in the mechanism of inhibitor action of n‐decylamine with concentration. The synergistic effect of n‐decylamine and chloride ions is discussed from the viewpoint of adsorption models.
TL;DR: In this paper, a mathematical model has been developed to describe the distribution of potential and current across concentric circular corrosion cells having unequal anodic and cathodic polarizabilities, which is applicable to galvanic couples, metal matrix composites, and localized corrosion effects.
Abstract: A mathematical model has been developed to describe the distribution of potential and current across concentric circular corrosion cells having unequal anodic and cathodic polarizabilities. This theory is essentially an extension of the Wagner‐Waber model to circular systems and is applicable to galvanic couples, metal matrix composites, and localized corrosion effects. The potential distribution in systems having unequal Wagner polarization parameters is not related in a simple way to the separate distribution curves for the two cases where the polarization parameters are equal. In thin‐layer electrolytes, there is a geometry effect in which the electrode polarization and current flow are concentrated near the anode/cathode juncture. The theory is applied satisfactorily to Pt/Fe model systems in dilute sodium chloride and to earlier results of Rosenfeld and Pavlutskaya with circular electrodes.
TL;DR: In this article, the corrosion of zinc in oxygenated solutions in the pH range 4-11 has been studied, with emphasis on the concurrent cathodic process, using rotating disc and ring disc electrodes.
Patent•
31 Oct 1977
TL;DR: In this article, a method for the production of metal articles resistant to corrosion at elevated temperatures is proposed, which involves the application of a first coating on an article surface, this coating comprising a cobalt, iron or nickel alloy which is compatible with the substrate and which is ductile in character.
Abstract: A method for the production of metal articles resistant to corrosion at elevated temperatures. The method involves the application of a first coating on an article surface, this coating comprising a cobalt, iron or nickel alloy which is compatible with the substrate and which is ductile in character. A second coating highly resistant to corrosion at elevated temperatures is applied over the first coating to form a composite coating, and an elevated temperature treatment follows to provide interfacial bonding and to minimize the detrimental effects of thermal and mechanical stresses encountered during use. The provision of a ductile first layer provides a barrier against degradation of the corrosion resistance of the outer layer and serves as a barrier against detrimental interdiffusion and crack propagation.
TL;DR: Tests in vitro indicate that the “safe” charge limit can be at least tripled by the use of imbalanced pulses, which may find application in the field of intramuscular stimulation where the present “ safe’ charge limit for stainless steel electrodes does not permit an adequate range of stimulation intensities.
Abstract: A form of cathodic protection has been developed for controlling the corrosion of stainless steel electrodes during electrical stimulation. The protection is achieved by using biphasic stimulation pulses with a slight (<-1%) charge imbalance in favor of the cathodic phase. Testsin vitro indicate that the “safe” charge limit (the charge density per phase at which corrosion first becomes serious) can be at least tripled by the use of imbalanced pulses. If confirmed by testsin vivo, this result may find application in the field of intramuscular stimulation where the present “safe” charge limit for stainless steel electrodes (#40 μC cm−2) does not permit an adequate range of stimulation intensities.
TL;DR: In this article, the authors measured the stress corrosion crack velocity and stress corrosion threshold stress intensity for Type 304L austenitic stainless steel in water with 42% MgCl2 at 130 C.
Abstract: Stress corrosion crack velocity and stress corrosion threshold stress intensity have been measured for Type 304L austenitic stainless steel in water with 42% MgCl2 at 130 C. The stress corrosion crack velocity vs stress intensity curve has a shape similar to the one for other austenitic steels and many other metallic and nonmetallic materials. The threshold stress intensity (KISCC is 8 ± 1 MN·m−3/2, and the plateau crack velocity is 3 to 6 × 10−8 m/s. Linear elastic fracture mechanics techniques can be applied to SCC testing of soft and tough materials, provided the KISCC is low enough, and crack branching can be avoided. Criteria for the formation of single, branched, and circular stress corrosion cracks are indicated.
TL;DR: In this article, a CoCrAlY + Pt coating for gas turbine airfoils is described, which is superior in oxidation and hot corrosion resistance to a coating made of the same material without platinum.
TL;DR: In this paper, the corrosion resistance of twelve Ni Cr dental casting alloys has been assessed by registering their potentiodynamic polarization curves, polarization resistance curves, and potential-time curves, in a de-aerated and aerated artificial saliva.
TL;DR: Blisters have been observed in the oxide film of aluminum in aqueous chloride solutions as discussed by the authors, and they can be initiated by short duration (⪝ 1 msec), low voltage pulses.
Abstract: Blisters have been observed in the oxide film of aluminum in aqueous chloride solutions. They can be initiated by short duration (⪝ 1 msec), low voltage pulses. Such blisters grow only if the steady‐state potential of the specimen is above the pitting potential. The growth proceeds laterally along the oxide‐metal interface. Upon breaking, as a result of gas pressure from within, pitting corrosion begins. Thus, in this instance, blisters are experimentally demonstrable precursors of pits.