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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 35 (1984), S. 219-226 
    ISSN: 1432-0630
    Keywords: 61.70Jc ; 66.30Jt+Lw ; 68.20+t
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Etch pit densities on iron (110) surfaces in sulphuric acid grow linearly with the interfacial hydrogen activity in excess of a critical activity. The hydrogen activity is approximately proportional to the square root of the cathodic current density. At constant cathodic current density the etch pit density increases with temperature and decreases with external stress. Dislocations at which the excess etch pits form penetrate into the iron at a rate proportional to the hydrogen activity and the square root of time. Effects of prior hydrogen deposition on the shape of etch pits are seen at depths greater than the penetration depth of hydrogen generated dislocations. Changes of etch pit shape similar to those produced by hydrogen are also found when external stress is applied. The results are compared to Prussin's theory in which the assumption is made that stresses accompanying diffusion of an impurity are fully relieved by plastic deformation and formation of dislocations for stresses exceeding a critical stress. While some of the predictions of the theory are met by the experiments, the dislocations penetrate into the iron much slower than diffusion of hydrogen, since dislocations cannot move fast enough, i.e. stresses are not fully relieved.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 9 (1979), S. 155-160 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The quantitative analysis of the morphology of dislocation-free {211} iron surfaces during electrochemical dissolution and measurements of distances and directions of monatomic steps provide information about the rates and potential dependences of three different elementary processes involving iron atoms bound to the lattice in three geometrically and energetically different states. The interaction of the three elementary processes explains the well-known anomalies of the kinetics of the iron electrode. A statistical analysis of the step distances is given.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 224 (1966), S. 45-62 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Permanganat wird in Natriumhydroxidlösungen an der rotierenden Scheibenelektrode polarographisch reversibel zu Manganat(VI) und zu Manganat(V) reduziert. Aus der Abhängigkeit der Halbwellenpotentiale der Manganat(VI)-Manganat(V)-Welle von der Hydroxylionenaktivität wurden die Hydrolysekonstante des Manganats(V) $$K = \frac{{a_{MnO_4 ^{3 - } } \times a_{H_2 O} }}{{a_{HMnO_4 ^{2 - } } \times a_{OH} }} = 0.3( \pm 0.1)$$ und das Normalpotential $$E_{{{MnO_4 ^{2 - } } \mathord{\left/ {\vphantom {{MnO_4 ^{2 - } } {MnO_4 ^{2 - } }}} \right. \kern-\nulldelimiterspace} {MnO_4 ^{2 - } }}} = 274( \pm 10) mV$$ mV bestimmt. Die irreversible Reduktion von Manganat(V) zu Oxid verläuft über ein Zwischenprodukt, das elektrochemisch wieder oxydiert werden kann. Das Zwischenprodukt, wahrscheinlich hydrolysiertes, monomeres Manganat(IV), reagiert in der Lösung zu nicht mehr oxydierbaren Produkten weiter. Geschwindigkeitsbestimmend ist eine homogene Reaktion 2. Ordnung, also die Dimersierung des Manganats(IV). Die Geschwindigkeitskonstante der Dimerisierung in 5 m Natronlauge wurde zu k2=2 · 105 Liter · Mol−1 · sec−1 abgeschätzt.
    Notes: Summary The reduction of permanganate to manganate(VI) and manganate(V) at the rotating disc electrode is polarographically reversible. The half-wave potentials of the manganate(VI)-manganate(V) wave depend on the hydroxyl ion activity of the solution due to the hydrolysis of manganate(V). The hydrolysis constant $$K = \frac{{a_{MnO_4 ^{3 - } } \times a_{H_2 O} }}{{a_{HMnO_4 ^{2 - } } \times a_{OH} }} = 0.3( \pm 0.1)$$ and the standard potential $$E_{{{MnO_4 ^{2 - } } \mathord{\left/ {\vphantom {{MnO_4 ^{2 - } } {MnO_4 ^{2 - } }}} \right. \kern-\nulldelimiterspace} {MnO_4 ^{2 - } }}} = 274( \pm 10) mV$$ were obtained from the measurements. During the irreversible reduction of manganate(V) an intermediate is formed, probably being a hydrolysed monomer of manganate(IV). The intermediate can be reoxidized at the ring electrode. It disappears by polymerisation and precipitation as an oxide, the rate determining step being a homogeneous reaction of the second order. The rate constant of that dimerisation was estimated to be k 2=2×105 liter × mole−1 × sec−1.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 307 (1981), S. 267-270 
    ISSN: 1618-2650
    Keywords: Best. von Wasser, Wasserstoff, Sauerstoff, Stickstoff in Ammoniak, Chromatographie, Gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird ein Verfahren zur simultanen gas-chromatographischen Bestimmung geringer Gehalte an Wasser, Wasserstoff, Sauerstoff und Stickstoff in gasförmigem oder flüssigem Ammoniak angegeben, das auch gelöste Salze enthalten darf. Die Gase werden an zwei hintereinander geschalteten Säulen, gefüllt mit Kohlenstoff-Molekularsieb und Silicat-Mokekularsieb, getrennt. Die Erfassungsgrenzen liegen bei 10 ppm (H2O), 12 ppm (H2), 5 ppm (O2) und 1ppm (N2).
    Notes: Summary A method was developed for the simultaneous gas-chromatographic determination of traces of water, hydrogen, oxygen, and nitrogen in gaseous or liquid ammonia which also may contain dissolved salts. The gases are separated on two consecutive columns filled with carbon molecular sieve and silica molecular sieve. Limits of detection are 10 ppm (H2O), 12 ppm (H2), 5 ppm (O2), and 1 ppm (N2).
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 18 (1967), S. 11-15 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Research on the corrosion of aluminium in water at high temperatures and pressuresThe stationary corrosion rate icorr of aluminium is measured electrochemically in a 10-3 m sodium bicarbonate solution at temperatures between 100°C and 200°C using a V4A high pressure loop, the result being \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} jcorr\, = \,5\, \cdot \,10^{- 6} \,\exp \frac{{15000}}{R}X \\ \,\,\,\,\,\,\,X\left({\frac{1}{T} - \frac{1}{{373}}} \right)\,A/cm^2 . \\ \end{array} $$\end{document} Thus, the effective activation energy is 15 kcal/mole. The stationary thicknesses of the oxide layer on aluminium are calculated as a function of the temperature from the corrosion rates and the weight changes of the specimen. The results are compared to the thicknesses measured microscopically.
    Notes: In einem Hochdruckkreislauf aus V4A wird die stationäre Korrosionsgeschwindigkeit icorr von Aluminium mit elektrochemischen Methoden im Temperatur-bereich zwischen 100 und 200° C in einer 10-3 molaren Natriumbicarbonatlösung gemessen. Es ergibt sich \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} jcorr\, = \,5\, \cdot \,10^{- 6} \,\exp \frac{{15000}}{R}X \\ \,\,\,\,\,\,\,X\left({\frac{1}{T} - \frac{1}{{373}}} \right)\,A/cm^2, \\ \end{array} $$\end{document} d. h. eine effektive Aktivierungsenergie von 15 kcal/mgl. Die stationäre Dicke der Oxydschicht auf dem Aluminium wird in Abhängigkeit von der Temperatur aus der Korrosionsgeschwindigkeit und der Gewichtsänderung der Aluminiums berechnet und mit der mikroskopisch ausgemessenen Dicke verglichen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 25 (1974), S. 234-234 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 26 (1975), S. 694-699 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Growth and dissolution of anodically obtained oxide layers on titaniumOxide films were grown by anodic polarization of titanium in various aqueous electrolytes. The field strength derived from film thickness and voltage is linearly related to the logarithm of the total current density. The current efficiency for film formation depends upon current density, pH-value, and film thickness. The dielectric constant of the film decreases with field strength from ε = 110 to ε = 7, but rises again at high field strengths and thick films.The dissolution rate of anodic oxide films on titanium was investigated as a function of pH-value, concentration of chloride, and temperature, respectively. Aging of the films in distilled water causes the dissolution rate to decrease by up to 3 order of magnitude.
    Notes: Während des Wachstums von Oxidschichten auf Titan in verschiedenen wäßrigen Elektrolytlösungen ist die aus Schichtdicke und Formierungsspannung ermittelte Feldstärke eine lineare Funktion des Logarithmus des Gesamtstromdichte. Die Stromausbeute für das Schichtwachstum hängt von der Stromdichte, dem pH-Wert und der Schichtdicke ab. Die Dielektrizitätskonstante der Schicht sinkt mit der Feldstärke zunächst von ε = 110 auf ε = 7 ab und wächst bei hohen Feldstärken und dicken Schichten wieder erheblich an.Die Auflösungsgeschwindigkeit anodisch erzeugter Oxidschichten auf Titan wurde in Abhängigkeit vom pH-Wert, der Chlorid-konzentration und der Temperatur untersucht. Während der Alterung der Schichten in destilliertem Wasser nimmt die Auflösungsgeschwindigkeit um bis zu 3 Zehnerpotenzen ab.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 32 (1981), S. 167-173 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Corrosion behaviour of iron and steel in liquid ammoniaPolarization curves were measured with iron in liquid ammonia containing various electrolytes of different acidities at - 40°C and + 20°C. The dissolution rate of iron by formation of iron(II) is independent of the electrolyte composition and follows a Tafel-line of the slope RT/2.0.4 F. At positive potentials iron becomes passive. The steady state current densities are nearly independent of the electrode potential and grow with acid concentration and temperature. At very positive electrode potentials the current densities again increase exponentially with the potential. The current efficiencies for nitrogen evolution and iron(III) dissolution are of equal magnitude. Iron oxidized in air exhibits an electrochemical behavior distinctly different from the one of iron passivated in liquid ammonia. Very probably the passivating layer is composed of iron nitride with a thickness of the order of nm. Passive steel FG 32 in the soft state after heat treatment corrodes at about the same rate as pure iron, but approximately 8 times faster in the cold worked state.
    Notes: An Eisen in flüssigem Ammoniak wurden bei -40°C und bei + 20°C Stromspannungskurven in stark und schwach sauren Elektrolytlösungen gemessen. Die Auflösungsgeschwindigkeit des aktiven Eisens zu Eisen(II) ist unabhägig von der Elektrolytzusammensetzung und folgt einer Tafel-Geraden mit der Neigung RT/2 · 0.4 F. Bei positiven Elcktrodenpotentialen wird das Eisen passiv. Die stationären Stromdichten sind nahezu potentialunabhängig und nehmen mit der Säurekonzentration und der Temperatur zu. Bei sehr positiven Elektrodenpotentialen wachsen die Stromdichten wieder exponentiell mit dem Potential. Die Stromausbeuten für, die Entwicklung von Stickstoff und die Eisen (III)-auflösung sind ähnlich groß. Luftpassives Eisen unterscheidet sich im elektrochemischen Verhalten deutlich von in Ammoniak passiviertem. Es entsteht sehr wahrscheinlich eine Eisennitridschicht mit einer Dicke der Größenordnung nm. Passiver Stahl FG 32 korrodiert im weichgeglühten Zustand etwa ebenso schnell wie reines Eisen, aber im kaltgezogenen Zustand rund 8mal schneller.
    Additional Material: 11 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 32 (1981), S. 197-200 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: The influence of water and dissolved gases on the corrosion behaviour of iron in liquid ammoniaOxygen increases the corrosion rate of active iron in liquid ammonia at + 20°C and passivates iron at concentrations exceeding a critical concentration which increases with the acidity. Water acts as an acid and increases the corrosion rate of passive iron up to 0.1 wt. %. At higher concentrations of water, corrosion is inhibited probably because of the precipitation of hydrated iron (III) oxide. Carbon dioxide always enhances the corrosion rate of passive iron acting as a strong acid and a strong complexing agent for iron (III). At high concentrations of carbon dioxide or ammonium carbaminate iron cannot be passivated.
    Notes: Sauerstoff erhöht die Korrosionsgeschwindigkeit des aktiven Eisens in flüssigem Ammoniak bei + 20 °C und passiviert das Eisen, sobald eine mit der Säurekonzentration abnehmende kritische Konzentration überschritten wird. Wasser wirkt als Säure und erhöht bis zu 0,1 Gew. % die Korrosionsgeschwindigkeit des passiven Eisens. Bei höheren Wassergehalten ist Wasser wahrscheinlich wegen der Ausfällung von hydratisiertem Eisen (III)-oxid ein Inhibitor. Kohlendioxid vergrößert stets die Korrosionsgeschwindigkeit des passiven Eisens. Es ist eine starke Säure und ein starker Komplexbildner für Eisen (III). Bei hohen Konzentrationen von Kohlendioxid oder Ammoniumcarbaminat kann das Eisen nicht mehr passiviert werden.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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