Showing papers on "Corrosion published in 1971"
TL;DR: In this article, the effect of catalytic effect of Cu and P on the oxidation of Fe(II) hydroxo-complexes in aqueous solutions has been investigated and the mechanism of atmospheric rusting deduced from the results obtained in the present investigation has been used to explain the difference in behaviour between ordinary mild steels and low alloy steels during atmospheric exposure.
236 citations
TL;DR: There are several explanations for the aggravation of corrosion of iron and steel in oxygen-free conditions by sulphate-reducing bacteria.
Abstract: THERE are several explanations for the aggravation of corrosion of iron and steel in oxygen-free conditions by sulphate-reducing bacteria. These are (a) stimulation of the cathodic part of the corrosion cell by the removal and utilization of the polarizing hydrogen by the bacteria1; (b) stimulation of the cathodic reaction by solid ferrous sulphides formed by the reaction of ferrous ions with sulphide ions produced by bacteria2; (c) stimulation of the anodic reaction, metal dissolution, by bacterially produced sulphide3; (d) local acid cell formation4, and (e) formation of iron phosphide by reaction of the metal with bacterially reduced phosphates5.
201 citations
TL;DR: In this article, the effect of the following factors on the mechanism and rate of pitting corrosion is discussed: composition of the corrosive medium, composition and structure of the metal or alloy, tempe...
Abstract: The effect of the following factors on the mechanism and rate of pitting corrosion is discussed: composition of the corrosive medium, composition and structure of the metal or alloy, tempe...
178 citations
TL;DR: In this article, some mechanistic aspects of the breakdown of passivity on stainless steels in chloride media are discussed along with those pertaining to the pit-propagation process.
170 citations
TL;DR: The effect of benzotriazole (BTA) on corrosion of copper in 5% NaCl has been studied by immersion tests, potentiostatic polarization, AC impedance measurements, and ellipsometric investigations as mentioned in this paper.
Abstract: The effect of benzotriazole (BTA) on corrosion of copper in 5% NaCl has been studied by immersion tests, potentiostatic polarization, AC impedance measurements, and ellipsometric investigations. It was found that BTA when present in the corrosive environment is a good inhibitor. The good electronic conductivity of the film formed on copper, the decreased double capacity, small film thickness, and decreased current on anodic polarization curves indicate that BTA is chemisorbed on the surface. This prevents adsorption of oxygen and formation of a prenucleation layer which is the forerunner of oxide formation. Discrepancies with results obtained by other investigators using infrared reflectance techniques are discussed.
159 citations
TL;DR: In this paper, the authors measured the permeability of H through iron and steel specimens as a function of compressive and tensile stress, and determined the critical concentration of H to cause embrittlement, calculated on the basis of the interaction energy.
150 citations
TL;DR: In this paper, an attempt has been made to apply quantum-chemical values to the selection and evaluation of corrosion inhibitors, and the calculation was carried out by the LCAO (Linear Combination of Atomic Orbitals) method for the homologous series of substituted pyridine derivatives.
125 citations
TL;DR: In this paper, a new method for determining the critical pitting potentials, Ec, of stainless steels in aqueous chloride environments has been developed, which has the advantage of defining a discrete value of Ec which is dependent only on the composition and structure of the metal and the test environment.
99 citations
78 citations
Patent•
23 Feb 1971
TL;DR: In this article, the magnetic fields produced by electrical current flowing into or exiting from a buried pipeline at the situs of a bare region of the pipeline at which corrosion may take place are detected.
Abstract: Electrical current patterns indicative of either the cathodic protection or the existence of external corrosion of a subsurface pipeline are detected by measuring the magnetic fields produced by electrical current flowing respectively into or exiting from the buried pipeline at the situs of a bare region of the pipeline at which corrosion may take place.
Patent•
29 Nov 1971TL;DR: Compositions for inhibiting corrosion and scale formation in aqueous systems which consist essentially of from 20 to 97.5% by weight of total composition of (a) a combination of zinc and hydrolyzed polymaleic anhydride and (b) 2.5 to 80% of total compositions of a corrosion inhibitor, particularly benzotriazole as discussed by the authors.
Abstract: Compositions for inhibiting corrosion and scale formation in aqueous systems which consist essentially of from 20 to 97.5% by weight of total composition of (a) a combination of zinc and hydrolyzed polymaleic anhydride and (b) 2.5 to 80% by weight of total composition of a corrosion inhibitor, particularly benzotriazole.
TL;DR: In this paper, an exact equation for the slope of the currentvoltage curve at the corrosion potential is derived, and two new formulae are valid approximations under all conditions.
TL;DR: The effect of benzotriazole on the corrosion of iron in has been studied in this article, and the experimental data are consistent with the slow proton discharge step for the hydrogen evolution reaction on iron.
Abstract: The effect of benzotriazole on the corrosion of iron in has been studied. The experimental data are consistent with the slow proton discharge step for the hydrogen evolution reaction on iron. No change in mechanism was observed by the addition of benzotriazole, but a significant decrease in the rate of hydrogen evolution was observed. The inhibitor concentration had a significant influence on the behavior of the open‐circuit capacitance. Surface coverages determined from capacitance and corrosion rate data were consistent and found to fit a Langmuir adsorption isotherm.
TL;DR: Findings based on one year of data suggest that amalgam made from dispersion-phase alloy is more resistant to corrosion than are the spherical-particle and conventional-type alloys.
Abstract: Three types of dental amalgam alloys (conventional, spherical-particle, and dispersion-phase) were compared for resistance to corrosion in vivo. After one year, it was found that: (1) Amalgam made with dispersion-phase alloy maintained a significantly higher degree of luster than did amalgam made with spherical-particle alloys (P According to these findings based on one year of data, amalgam made from dispersion-phase alloy is more resistant to corrosion than are the spherical-particle and conventional-type alloys.
01 Mar 1971
TL;DR: In this article, a study of Al-Zn-Mg alloys was undertaken to establish the specific combination of mechanical and thermal conditions which are necessary for stress-corrosion susceptibility to occur.
Abstract: This study of Al-Zn-Mg alloys was undertaken to establish the specific combination of mechanical and thermal conditions which is necessary for stress-corrosion susceptibility to occur in these alloys. The work included a study by electron transmission microscopy of the microstructure of this alloy system. A new mechanism is proposed to account for the observations made. It suggests that the high corrosion potential at grain boundaries in stress-corrosion susceptibile Al-Zn-Mg alloys is due to segregation of zinc and magnesium. By taking precautions to reduce this segregation, the stress-corrosion life can be increased.
TL;DR: In this paper, the active to passive transition in the corrosion of SiC has been studied at 1000°C and 1200°C with O 2, H 2 O vapour and CO 2 as oxidants.
TL;DR: In this article, the mechanism of crevice corrosion of stainless Cr steels in neutral 3%NaCl solution has been studied in a cell constructed for this purpose, and both pH and potential of the steel surface increase as a result of alkali formation (O 2 reduction) during corrosion of the stainless steel in the passive state and thickening of the air-formed oxide film.
TL;DR: In this article, the electrochemical basis for the differentiation between hydrogen embrittlement and active path corrosion is examined along with the consequences of the recently demonstrated acidification that occurs in areas of localized geometry such as precracks, pits, and crevices.
Abstract: This paper reviews previously proposed mechanisms for the environmentally induced cracking of high strength steels in sodium chloride. The electrochemical basis for the differentiation between hydrogen embrittlement and active path corrosion is examined along with the consequences of the recently demonstrated acidification that occurs in areas of localized geometry such as precracks, pits, and crevices. From electrochemical studies on a modified 12% chromium martensitic stainless steel, data are presented which indicate that hydrogen absorption occurs under conditions of exposure previously thought to preclude this possibility; that is, at applied bulk potentials noble to the reversible hydrogen potential. Data are also presented to show that the activation energy for crack growth at the corrosion potential and at cathodic and anodic applied potential is 9.5 Kcal/mole (±1); a value close to that reported previously for the cracking of cathodically embrittled steel. The experimental data are expla...
TL;DR: In this article, the causes of loss of corrosion resistance and ductility of AISI Type 446 steel with high chromium content have been investigated and changes in composition and heat treatment that would improve their material properties.
Abstract: The ferritic alloys, particularly AISI Type 446 steel with its high chromium content, have desirable properties of corrosion resistance, low raw material cost, and resistance to stress corrosion cracking (SCC); yet they are not widely used in construction work because of the damaging effects of high temperature exposures (such as welding) on their corrosion resistance and ductility. This work describes the causes for their loss of corrosion resistance and ductility, and defines changes in composition and heat treatment that would improve their material properties.
TL;DR: In this article, a three-to fourfold increase in strength and corrosion resistance was observed when performed specimens were impregnated with monomer and polymerized, and the results were used to evaluate the structural properties of polymer-cement and polymer-mortar composites.
TL;DR: In this paper, the electrochemical behavior of high purity aluminum has been studied to clarify the corrosion behavior of the metal when exposed to oxygen free and oxygen saturated saline solutions of varying pH.
Abstract: The electrochemical behavior of high purity aluminum has been studied to clarify the corrosion behavior of the metal when exposed to oxygen free and oxygen saturated saline solutions of varying pH. The mixed or corrosion potential, EM, of the electropolished high purity aluminum decreases as the pH is increased except in the intermediate pH range (4 to 8) where EM increases. A local maximum in the corrosion potential curve as a function of pH is thus observed. The potentiostatic polarization data and controlled potential weight loss data obtained at pH 4.0 suggest that the rate of dissolution of high purity aluminum is independent of electrode potential over a fairly wide range, relatively insensitive to the presence of dissolved oxygen in the electrolyte, and highly sensitive to changes in pH. Based on the potentiostatic data, a corrosion diagram believed to be approximately valid from pH 0 to pH 14 has been constructed. The corrosion diagram is consistent with the observed relation between EM a...
Patent•
Esso1
TL;DR: In this article, the authors show that the negative negative conrocession in COOLING WATER systems is substantially reduced by the addition of SMALL AMOUNTS of a SILICATE and a GLUCONATE, a POLYPHOSPHATE can also be added if desired.
Abstract: OXIDATIVE CORROSION IN COOLING WATER SYSTEMS IS SUBSTANTIALLY REDUCED BY THE ADDITION OF SMALL AMOUNTS OF A SILICATE AND A GLUCONATE. A POLYPHOSPHATE CAN ALSO BE ADDED IF DESIRED.
TL;DR: The sulfldation kinetics of a Ni−20 w/o (weight per cent) Cr alloy exposed to hydrogen sulfide•hydrogen atmospheres at 700°C have been determined as a function of the sulfur pressure.
Abstract: The sulfldation kinetics of a Ni‐20 w/o (weight per cent) Cr alloy exposed to hydrogen sulfide‐hydrogen atmospheres at 700°C have been determined as a function of the sulfur pressure. The morphology and phase composition of the duplex sulfide scale formed as a corrosion product have been investigated. The kinetics appear to be controlled by diffusion of the reactants through the scale. No significant dependence of the parabolic rate constant on the sulfur pressure has been determined within the wide range . A correlation is presented for the growth kinetics and the structural features of the nickel and chromium sulfide constituents of the scales with the ternary nickel‐chromium‐sulfur phase diagram.
TL;DR: In this paper, the surface of a 18−Cr 8−Ni stainless steel electrode in 1% NaCl was reported to have an increased corrosion current, and the major part of the current increase was attributed to plastic deformation of the metal surface.
Patent•
13 Dec 1971
TL;DR: In this article, a process and composition for blast-cleaning metal surfaces, particularly steel surfaces, and simultaneously depositing a corrosion protective metal thereon is described. But this process is restricted to a small number of surfaces.
Abstract: A process and composition for blast-cleaning metal surfaces, particularly steel surfaces, and simultaneously depositing a corrosion protective metal thereon. Abrasive particles carrying a protective metal, especially zinc, at their outer surface are used as the blast abrasive. The protective metal is bound to the abrasive particles by means of a binder.
TL;DR: In this article, the essential nature of protective rust films formed on low-alloy, weathering steels by atmospheric exposure has been clarified as to electrochemical behavior, catalytic ability to form sulphate from SO2 in the atmosphere, and distribution of active corrosion sites on rusted steel surfaces.