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  • Chromatographie, Gas  (3)
  • Coleoptera
  • oxidation
  • Springer  (6)
  • Annual Reviews
  • 1980-1984
  • 1975-1979  (6)
  • 1978  (6)
Collection
Publisher
  • Springer  (6)
  • Annual Reviews
Years
  • 1980-1984
  • 1975-1979  (6)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 12 (1978), S. 247-256 
    ISSN: 1573-4889
    Keywords: oxidation ; iron ; magnetite ; oxide thickness ; electron back-scattering Mössbauer spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Magnetite films in the range 265–4520 Å have been grown on natural iron substrates and subsequently investigated by electron back-scattering Mössbauer spectroscopy. In particular, the percentage, P, of the total spectrum area contributed by the oxide has been determined as a function of oxide thickness, d. It was found that d up to ≈ 3000Å may be expressed (to an accuracy of ∼ 5%) by d (Å)=−1.95 × 103 ln (1–0.01 P). The experimental data have been compared with the theoretical predictions of both Huffman and Bainbridge. Good agreement between experiment and Huffman's predictions of P is obtained using values of the electron attenuation coefficient, μ, of 1.10 × 104 cm2 g−1 for the 7.3 keV electrons and 1.73 × 104 cm2 g−1 for the 5.4 keV electrons. A good fit of our data to Bainbridge's expression requires a somewhat lower effective μ, value of 0.8 × 104 cm2 g−1. The experimental P value for the thickest oxide (4520 Å) is lower than the theoretical predictions, probably as a result of a neglected mechanism recently identified by Tricker, Ash, and Cranshaw.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 12 (1978), S. 35-66 
    ISSN: 1573-4889
    Keywords: CoCrAl ; oxidation ; oxide scale adherence ; rare-earth effect ; hafnium ; yttrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of small amounts of yttrium (up to 1 wt. %) and hafnium (up to 1.5 wt.%) on the oxidation behavior of Co-Cr-Al alloys in the temperature range 1000–1200°C for times up to 1000 hr in air has been studied. The major portion of the study has been concerned with Co-10Cr-11Al base alloys. Both isothermal and cyclic tests have been carried out; the cycle used consisted of 20 hr at temperature, followed by cooling to room temperature. Both additions reduce the overall oxidation, Hf somewhat more so than Y. In part, this is due to the improved adhesion between scale and alloy reducing scale spallation at temperature, and in part due to possible modification of the Al2O3 grain size. The former factor is far more critical under thermal cycling conditions. Under isothermal conditions the oxidation rate increases with increasing Hf content with all but the 1.5 wt.% alloy oxidizing more slowly than the Hf-free alloy; increase in Y content has the reverse effect. Under thermal cycling conditions the 0.3 and 1.0 wt.% Hf alloys show the lowest overall weight gain. Metallographic evidence suggests that the improved scale adhesion is due principally to a pegging mechanism; the active elements promote the growth of intrusions of Al2O3 into the alloy. However, if the intrusions are too large, they can act as initiators of scale failure.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 12 (1978), S. 67-82 
    ISSN: 1573-4889
    Keywords: oxidation ; Fe-C ; kinetics ; oxide grain size ; grain-boundary diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fe-C alloys containing 0.1, 0.5, and 1.0% C were oxidized in 1 atm O2 at 500°C. Two specimen preparations were used: annealed followed by slow cooling to form coarse pearlite plus proeutectoid ferrite or cementite; and cold-worked by abrading after annealing. The cold-worked alloys oxidize more rapidly. Annealed pearlite oxidizes faster than annealed ferrite. The differences in oxidation rate are caused by differences in the Fe3O4 grain size, that is, by the number of oxide grain boundaries available to act as easy diffusion paths for the outward diffusion of Fe through the Fe3O4. The oxidation rate constant is 10 times larger for fine-grained poly crystalline oxide than for oxide in which the Fe3O4 is monocrystalline.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 291 (1978), S. 299-307 
    ISSN: 1618-2650
    Keywords: Analyse von Kohlenwasserstoffen in Luft ; Chromatographie, Gas ; Tieftemperaturgradientenrohr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird über ein gas-chromatographisches Verfahren zur Bestimmung von Alkanen, Alkenen und Aromaten in der Außenluft berichtet, bei dem die Probenahme an Tenax GC oder Carbopack mit Hilfe eines Tieftemperaturgradientenrohres erfolgt und die Analyse unter Einsatz eines Doppelsäulensystems in Verbindung mit zwei Flammenionisationsdetektoren durchgeführt wird. Eingehende Untersuchungen zum Verhalten der Substanzen bei der Probenahme zeigen, daß die Trocknung der Probeluft mit Magnesiumperchlorat das Ergebnis nicht beeinflußt und für Kohlenwasserstoffe mit drei oder mehr C-Atomen keine auf Durchbruch zurückzuführenden Substanzverluste zu befürchten sind. Bei einem Probenahmevolumen von 51 Luft können 2 μg Substanz/m3 gut bestimmt werden. Für Außenluft-Konzentrationen von 45 μg Benzol/m3, 95 μg Toluol/m3 und 35 μg n-Pentan/m3 betrugen die Standardabweichungen 3,5, 6,0 bzw. 3,6 μg/m3. Bei leichter Modifikation des Systems ist mit derselben Probenahmevorrichtung die gleichzeitige Bestimmung von Kohlenwasserstoffen mit einem Flammenionisationsdetektor und von Organohalogen Verbindungen mit einem Elektroneneinfangdetektor möglich.
    Notes: Summary A method is described for the gas-chromatographic determination of alkanes, alkenes and aromatics in ambient air. The hydrocarbons are trapped by cryogenic sampling using Tenax GC or Carbopack as adsorbing material and are analyzed in a two-column system equipped with two flame-ionization detectors. A detailed examination of the sampling procedure shows that drying the air with magnesium perchlorate does not affect the results, and losses of substances due to break-through need not be reckoned with for hydrocarbons with three and more carbon atoms. In a 51 air sample 2 μg/m3 of hydrocarbons can be determined readily. The standard deviations for benzene, toluene and n-pentane were 3.5, 6.0 and 3.6 μg/m3 at ambient air concentrations of 45, 95 and 35 μg/m3. A slight modification of the system which includes the combined use of a flame-ionization detector and an electron-capture detector permits the simultaneous determination of hydrocarbons and halogenated hydrocarbons.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 385-390 
    ISSN: 1618-2650
    Keywords: Best. von Carbonsäuren, Sulfonsäuren ; Chromatographie, Gas ; Spuren in wäßrigem Medium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Gas-chromatographische Methoden für die Spurenbestimmung einiger Carbonund Sulfonsäuren in wäßrigem Medium werden beschrieben. Die Nachweisvermögen für Ameisensäure, Essigsäure, Propionsäure, n-Buttersäure, n-Valeriansäure, Capronsäure, Acrylsäure, Benzoesäure und Chloressigsäure sowie für Methansulfonsäure und Äthansulfonsäure liegen zwischen 1 · 10−7 und 8 · 10−7 Mol/Liter. Anreicherung und Derivatisierung werden bei den Carbonsäuren durch Gefriertrocknung der Tetra-n-butylammoniumsalze und deren Umsetzung mit Benzylbromid zu den Benzylestern, bei den Sulfonsäuren durch Gefriertrocknung der Silbersalze und deren Umsetzung mit n-Butyljodid zu den n-Butylestern erreicht.
    Notes: Summary Gas-chromatographic methods for the determination of traces of several carboxylic and sulphonic acids in aqueous media are presented. Detection limits for formic, acetic, propionic, n-butyric, isobutyric, n-valeric, caproic, acrylic, benzoic, and chloroacetic acids as well as of methanesulphonic and ethanesulphonic acids range from 1 · 10−7 moles/liter to 8 · 10−7 moles/liter. Preconcentration and derivatisation of the carboxylic acids are achieved by freezedrying their tetra-n-butylammonium salts and converting the latter into the benzyl carboxylates using benzyl bromide. The sulphonic acids are converted to the corresponding silver salts, freeze-dried, and then esterified using n-butyl iodide.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 290 (1978), S. 316-316 
    ISSN: 1618-2650
    Keywords: Best. von Dimethylchlorsilan in Trichlorsilan ; Chromatographie, Gas ; Chlorierung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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