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Derrek G. Owen

Bio: Derrek G. Owen is an academic researcher from Atomic Energy of Canada Limited. The author has contributed to research in topics: Dissolution & Copper. The author has an hindex of 10, co-authored 26 publications receiving 560 citations.

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TL;DR: The initial stages of corrosion of iron by unstirred saturated aqueous H/sub 2/S solutions at 21/sup 0/C and atmospheric pressure have been examined as a function of time, pH (from 2 to 7, adjusted by addition of H/Sub 2/SO/sub 4/ or NaOH), and applied current as discussed by the authors.
Abstract: The initial stages of corrosion of iron by unstirred saturated aqueous H/sub 2/S solutions at 21/sup 0/C and atmospheric pressure have been examined as a function of time, pH (from 2 to 7, adjusted by addition of H/sub 2/SO/sub 4/ or NaOH), and applied current. Detailed examination of the morphology and phase identity of the corrosion products has led to a qualitative mechanistic understanding of the corrosion reactions. Mackinawite (tetragonal FeS/sub 1-x/) is formed by both solid-state and precipitation processes. Cubic ferrous sulfide and troilite occur as precipitates between pH = 3 and pH = 5, subsequent to metal dissolution upon cracking of a mackinawite base layer formed by a solid-state mechanism. The corrosion rate, and the relative amounts of these phases produced, are controlled by pH, applied current, and the degree of convection. The corrosion rate increases with decreasing pH; the quantity of precipitated material peaks near pH = 4, below which dissolution becomes the dominant process as the solubilities of the sulfide solids increase. Significant passivation was observed only at pH = 7, when the initial mackinawite base layer remained virtually intact. The solid-state conversion of cubic ferrous sulfide to mackinawite at 21/sup 0/C was monitored by x-raymore » diffractometry. The resulting kinetics are consistent with the Avrami equation for a nucleation and growth process with a time exponent of 3.« less

255 citations

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TL;DR: In this article, the anodic oxidation of copper in LiOH solution has been investigated by galvanostatic, potentiostatic and voltammetric sweep technique, and the structure and composition of the films were determined by x-ray and electron diffraction, and by scanning electron microscopy.
Abstract: The anodic oxidation of copper in LiOH solution has been investigated by galvanostatic, potentiostatic, and voltammetric sweep technique. The structure and composition of the films were determined by x-ray and electron diffraction, and by scanning electron microscopy. Cu(OH)/sub 2/ forms in two layers: a base layer grown by a solid-state mechanism and an upper layer of individual crystals nucleated and grown from solution. The size and number of upper layer crystals are dependent on electrode potential. More anodic potentials produce a large number of randomly deposited crystals, whereas less anodic potentials result in fewer, more highly developed crystals. Increased stirring results in a greater loss of material into solution, and in the extreme, nucleation and growth are completely prevented. For sufficiently low crystallization rates, produced galvanostatically, the thermodynamically stable phase, CuO, is formed. At higher rates the formation of Cu(OH)/sub 2/ dominates. A nucleation and growth mechanism is given and discussed with reference to other metal systems.

88 citations

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TL;DR: In this article, the surface oxidation of UO2 fuel pellets at 229 to 275°C has been monitored by X-ray diffractometiy and the existence of β-UO2.33 as a significant intermediate product of oxidation was confirmed, and a method for its quantitative estimation on the pellet surface was derived.

55 citations

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TL;DR: In this article, the authors described the oxidation of unused CANDUTM UO2 fuel in air-steam mixtures in a closed system at 200 and 225°C.

47 citations

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TL;DR: The limits of miscibility within a portion of the system Na2O-ZnO-B2O3-SiO2 were determined at 650°, 800°, and 950°C as mentioned in this paper.
Abstract: The limits of miscibility within a portion of the system Na2O-ZnO-B2O3-SiO2 were determined at 650°, 800°, and 950°C. The miscibility gap at 800° and 950°C is a low dome, adjoining the zinc borosilicate miscibility gap. Below 755°C the dome intersects the Na2O-B2O3-SiO2 face of the phase diagram. The locus of this intersection is in agreement with literature data on the sodium borosilicate system. Estimated tie-line placement in the ZnO-B2O3-SiO2 miscibility gap at 1300°C resembles those reported for the corresponding CaO and SrO systems. The microscopic morphology of glasses with the weight composition xNa2O-18ZnO-18B2O3-64SiO2 with 0≤×≤12 is described in detail.

24 citations


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1,235 citations

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TL;DR: This brief review traces the historical twists in the perception of SRB-induced corrosion, considering the presently most plausible explanations as well as possible early misconceptions in the understanding of severe corrosion in anoxic, sulfate-rich environments.
Abstract: About a century ago, researchers first recognized a connection between the activity of environmental microorganisms and cases of anaerobic iron corrosion. Since then, such microbially influenced corrosion (MIC) has gained prominence and its technical and economic implications are now widely recognized. Under anoxic conditions (e.g., in oil and gas pipelines), sulfate-reducing bacteria (SRB) are commonly considered the main culprits of MIC. This perception largely stems from three recurrent observations. First, anoxic sulfate-rich environments (e.g., anoxic seawater) are particularly corrosive. Second, SRB and their characteristic corrosion product iron sulfide are ubiquitously associated with anaerobic corrosion damage, and third, no other physiological group produces comparably severe corrosion damage in laboratory-grown pure cultures. However, there remain many open questions as to the underlying mechanisms and their relative contributions to corrosion. On the one hand, SRB damage iron constructions indirectly through a corrosive chemical agent, hydrogen sulfide, formed by the organisms as a dissimilatory product from sulfate reduction with organic compounds or hydrogen ("chemical microbially influenced corrosion"; CMIC). On the other hand, certain SRB can also attack iron via withdrawal of electrons ("electrical microbially influenced corrosion"; EMIC), viz., directly by metabolic coupling. Corrosion of iron by SRB is typically associated with the formation of iron sulfides (FeS) which, paradoxically, may reduce corrosion in some cases while they increase it in others. This brief review traces the historical twists in the perception of SRB-induced corrosion, considering the presently most plausible explanations as well as possible early misconceptions in the understanding of severe corrosion in anoxic, sulfate-rich environments.

566 citations

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TL;DR: In this paper, it was shown that acid volatile sulfide (AVS) is not equivalent to FeS and solid FeS phases have rarely been identified in marine sediments.

561 citations

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TL;DR: In this paper, X-ray diffraction, cyclic voltammetry, chronoamperometry, and in situ Raman spectroscopy were used to investigate the electrochemical oxygen evolution reaction (OER) on Cu, Cu2O, Cu(OH)2, and CuO catalysts.
Abstract: Scanning electron microscopy, X-ray diffraction, cyclic voltammetry, chronoamperometry, in situ Raman spectroscopy, and X-ray absorption near-edge structure spectroscopy (XANES) were used to investigate the electrochemical oxygen evolution reaction (OER) on Cu, Cu2O, Cu(OH)2, and CuO catalysts. Aqueous 0.1 M KOH was used as the electrolyte. All four catalysts were oxidized or converted to CuO and Cu(OH)2 during a slow anodic sweep of cyclic voltammetry and exhibited similar activities for the OER. A Raman peak at 603 cm–1 appeared for all the four samples at OER-relevant potentials, ≥1.62 V vs RHE. This peak was identified as the Cu–O stretching vibration band of a CuIII oxide, a metastable species whose existence is dependent on the applied potential. Since this frequency matches well with that from a NaCuIIIO2 standard, we suggest that the chemical composition of the CuIII oxide is CuO2–-like. The four catalysts, in stark contrast, did not oxidize the same way during direct chronoamperometry measurement...

501 citations