Showing papers in "Journal of The Electrochemical Society in 1958"
597 citations
TL;DR: In this paper, the diffusion coefficient of oxygen in zirconium and dilute alloys has been studied in the temperature rsmge of 400° to 585°C by observing the rates of dissolution of anodically deposited interference oxide films.
Abstract: The diffusion of oxygen in zinonium and dilute zirconium alloys has been studied in the temperature rsmge of 400° to 585°C by observing the rates of dissolution of anodically deposited interference oxide films. The diffusion coefficient of oxygen in zirconium depends on the grain orientation and varies by a factor of two among different orientations. Macroscopically observed average values obey the equation D(cm 2/sec) = 9.4 exp [(-51,780±220)/RT], where the activation energy for the diffusion of oxygen in zirconium is 51.78 kcal/mole. No macroscopic differences were observed in the diffusion coefficients of the various dilute alloys. Oxidation and corrosion rates have been observed to have an orientation dependence similar to that observed in the diffusion study. The mechanism of oxidation and corrosion is discussed in terms of diffusion of oxygen and adherence of oxide films.
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TL;DR: In this article, the authors measured the length of the potential plateau (transition time) during the electrochemical reduction of the PbO/sub 2/ layers, with a constant current, taking into account self-discharge and degree of utilization of the O/sub2/ layer.
Abstract: The total amount of anodic oorrosion of Pb and PbSb alloys in suifuric acid under conditions of O/sub 2/ evolution can be evaluated by measuring the length of the potential plateau (transition time) during the electrochemical reduction of the PbO/sub 2/ layers, with a constant current, taking into account self-discharge and degree of utilization of the PbO/sub 2/. Using high resolution techniques, a characteristic step in the potential plateau during discharge of the PbO/sub 2/ layer was discovered. This step ean be attributed to a difference in discharge overvoltage between alpha and BETA -PbO/sub 2/. For alloys of the Pb-Sb system, constant current corrosion increases slightly with increasing Sb concentration, whereas oxygen overvoltage decreases and constant potential corrosion strongly increases with increasing Sb concentration. Precise electrode potential measurements of the alpha -PbO/sub 2/PbSO/sub 4/ and the BETA -PbO/sub 2/ PhSO/sub 4/ couple dave 1.7085 plus or minus 0.0005 v and 1.7015 plus or minus 0.0005 v, respectively, vs. H/sub 2/ in 4.40M sulfuric acid at 31.8 d C. These two oxides have different oxygen overvoltage characteristics. Removal of oxygen from BETA -PbO/sub 2/ results in a new crystalline compound PbO/sub x/ with x 1.4 to 1.6, with a pseudo-face- centeredmore » cubic orthorhombic lattice. This new compound is a nonconductor. The influence of the oxygen content of the lead oxides on their electrochemical behavior is discussed. (auth)« less
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TL;DR: In this paper, a two-step mechanism for the reduction of molybdate ion in the presence of a codepositing metal is proposed and an explanation of why this metal must be iron, cobalt, or nickel rather than such metals as chromium, manganese, copper, or zinc is presented.
Abstract: Cathode potential measurements are used to explain the cathode reactions that result in the electrodeposition of molybdenum alloys. Potentials were measured by the direct method during the electrolysis of aqueous ammoniacal citrate solutions containing sodium molybdate and the sulfate of a codepositing metal, iron, nickel, or cobalt. The results indicate that the reduction of molybdate ion in this type of bath is probably not accomplished in one step with six electrons, but with one, two, or three electrons depending on the codepositing metal and its oxidation state in the bath. The results also indicate that hydrogen is involved in the molybdate reduction process. A two‐step mechanism for the reduction of molybdate ion in the presence of a codepositing metal is proposed and an explanation of why this metal must be iron, cobalt, or nickel rather than such metals as chromium, manganese, copper, or zinc is presented.
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58 citations
TL;DR: The effect of current density, pH, and temperature on the anodic behavior, cathodic behaviour, and corrosion of magnesium in aqueous solutions has been studied as mentioned in this paper, and a tentative mechanism for the anode oxidation of magnesium is postulated.
Abstract: The effect of current density, pH, and temperature on the anodic behavior, cathodic behavior, and corrosion of magnesium in aqueous solutions has been studied. A tentative mechanism for the anodic oxidation of magnesium is postulated. Local corrosion and/or undermining of metallic magnesium at the anode are appreciable and may, in fact, account for the observed low anodic current efficiencies of magnesium. An intergrannular type of corrosion occurs at cathodically polarized magnesium at elevated temperatures. A hydrogen embrittlement theory is proposed to explain intergranular cathode corrosion. (auth)
TL;DR: In this article, it was shown that the film thickness is proportional to the voltage drop across the film, and the proportionality constant does not depend on the length of time which the voltage is left applied.
Abstract: In order to avoid solvent action by the electrolyte during anodic oxidation of aluminum. the electrolyte must have a high buffering capacity. With such an electyte the conversion of aluminum to aluminum oxide is essentially quantitative. The film thickness is proportional to the voltage drop across the film, and the proportionality constant does not depend on the length of time which the voltage is left applied. The film contains, as an essential part of its structure. a quantity of the anion from the electrolyte. The film appears to be nonstoichiometric, having excess aluminum during formation, the amount of excess decreasing with increased length of anodizing time. The coulombic transfer during film formation is quantitatively accounted for during formation by oxidation of aluminum to the trivalent state and liberation of oxygen gas. After the film growth has ceased. the current can be only partially accounted for by oxygen evolution, but it is thought that this is because of difficulty in nucleating oxygen bubbles. (auth)
TL;DR: In this paper, it was shown that nonporous anodic oxide grows at, or close to, the oxide-electrolyte interface; it is concluded that the aluminum ion is the mobile species.
Abstract: It is demonstrated, by a series of marker experiments, in which layers of nonporous anodic oxide were tagged by incorporating radioactive material in them, that nonporous anodic oxide grows at, or close to, the oxide-electrolyte interface; it is concluded that the aluminum ion is the mobile species. Similar experiments with a porous oxide may also be interpreted in terms of formation of the oxide at the oxide-electrolyte interface, but in this case the interface is at the bottom of pores filled with electrolyte.
TL;DR: In this article, an electron microscopic study of the oxide films formed on niobium permits the apparently anomalous oxidation rate behavior of Niobium to be explained in terms of the formation of small, blister-like cracks in the oxide film.
Abstract: An electron microscopic study of the oxide films formed on niobium permits the apparently anomalous oxidation rate behavior of niobium to be explained in terms of the formation of small, blister-like cracks in the oxide film. An oxidation model, based on the idea that an oxidation process which is maintained by interstitial-anion or anion-vacancy diffusion leads to the generation of stresses in the oxide film, is proposed to account for these results. Finally, the observation of similar blister-like cracks in oxide films on tantalum is also reported.
TL;DR: In this paper, a single phase solid solution of hydrogen in niobium was produced throughout most of the system, and the equilibrium solubility exactly followed a simple pressure dependency.
Abstract: Equilibria in the niobium--hydrogen system were determined in the range 100 deg to 900 deg C, 10 to 1000 mm of mercury hydrogen pressure, and atomic ratios of hydrogen to niobium of 0.01 to 0.85. A single phase solid solution of hydrogen in niobium was produced throughout most of the system. In no region did the equilibrium solubility exactly follow a simple pressure dependency. The heat of solution increased with hydrogen content, which behavior may be related to an expansion in the niobium lattice.
TL;DR: In this article, the Czochralski technique was used to grow aluminum and antimony of high purity by zone refining, and the resistivity of as-grown P-type crystals can be decreased substantially by doping with carbon and increased by small quantities of Se and Te.
Abstract: Aluminum and antimony of high purity were prepared by zone refining. and single crystals of AlSb were grown by the Czochralski technique. Effects of various impurities in the starting materials and crucibles on the electrical properties are discussed, and equipment for crystal growing under equilibrium vapor pressure of Sb is described. The resistivity of as-grown-P-type crystals can be decreased substantially by doping with carbon and increased by small quantities of Se and Te. A larger quantity of Te will charge the crystals to Ntype. P-N junctions were made by controlled doping during crystal growing. Effects of various surface treatments on the electrical properties of AlSb are discussed, and some data on point contact and P-N junction diodes are presented. (auth)
IBM1
TL;DR: In this article, two distinct higher oxides of silver were produced by several chemical and electrochemical procedures, and they are shown to have a monoclinic structure for which lattice constants are derived.
Abstract: Samples of higher oxides of silver were prepared by several chemical and electrochemical procedures. Two distinct higher oxides were produced. The first, argentic oxide, , is a black powder and has a monoclinic structure for which lattice constants are derived. There is no evidence of the existence of other crystalline forms of . The second oxide, with silver in a valence state higher than plus two, is present in some preparations along with . The stoichiometry was not determined. It is also black and has a face‐centered cubic lattice. It decomposed to gradually over a period of months.
TL;DR: In this paper, it is shown that in evaluating the rates of anodic dissolution processes, it is necessary to consider the influence of the positive and negative difference effects; otherwise ions going into solution with uncommon valency may be found.
Abstract: It is shown that in evaluating the rates of anodic dissolution processes it is necessary to consider the influence of the positive and negative difference effects; otherwise ions going into solution with uncommon valency may be found. Scale fragments detached from an aluminum anode by the current passing through it could be seen. The hypothesis of valence change of ions while a current is passing through the anode does not explain all observed facts, but they can be well explained by the theory developed for the positive and negative difference effects.
TL;DR: In this article, it was shown that the reaction is controlled mainly by polarization of the cathcde where oxygen molecules are reduced to ions, and that the electron transfer is accomplished by the metal gauze and ions migrate through the borate melt.
Abstract: ll nickel is covered by a borate melt under an oxygen atmosphere, practically no oxidation takes place. li, however, the nickel sample is in electrical contact with an electronic conductor, e.g., a noble metal gauze, which extends up to the melt--oxygen irterface, nickel is attacked rapidly by virtue of local cell action. In this case, electron transfer is accomplished by the metal gauze and ions migrate through the borate melt. Electrochemical measurements show that the reaction is controlled mainly by polarization of the cathcde where oxygen molecules are reduced to ions. (auth)
TL;DR: In this paper, it was shown that Niobium oxide oxidizes in a complex manner, and the adherence of the oxide is poor above the transition point of the parabolic rate law at a weight gain of 55 to 70 mu g/cm/.
Abstract: Niobium has been found to oxidize in a complex manner. At 400 deg C and lower a slow rate of reaction is observed with the kinetics foilowing the parabolic rate law. At a weight gain of 55 to 70 mu g/cm/ a transition in the kinetics occurs to a nearly linear rate law. Between 550 deg and 625 deg C the oxidation rate is nearly constant as a function of temaperature, while above 625 deg C the oxidation rate again increases with the temperature. The adherence of the oxide is poor above the transition point. (auth)