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  • 1985-1989
  • 1980-1984  (3)
  • Polymer and Materials Science  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 32 (1981), S. 1-7 
    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: Die Oxidation von 18/8 Stählen in Kohlendioxid + 2% Kohlenmonoxid bei hohem DruckDie Oxidation verschiedener 18/8 Stähle in Gemischen aus Kohlendioxid und 2% Kohlenmonoxid wurde im Temperaturbereich 550 bis 650°C durch intermittierende Messung der Gewichtszunahme, metallographische Untersuchung, Fraktographie und Rasterelektronenmikroskopie verfolgt. Schon in einem frühen Oxidationsstadium entsteht eine Duplex-Zunderschicht. Die Gewichtszunahme/Zeit-Kurven zeigen zwei Prozeßstufen, und zwar ein Anfangsstadium, das sich exponentiell dem zweiten langsameren Stadium annähert. Die Geschwindigkeit der Duplex-Zunderbildung zeigte nicht die übliche Temperaturabhängigkeit; indessen wurde bei etwa 600°C ein Maximum der Geschwindigkeit festgestellt. Die sekundären Verzunderungsgeschwindigkeiten waren bei 650 und 550°C deutlich zu erkennen und lagen bei der niedrigeren Temperatur höher. Im Zunder traten verschiedene Spinelle auf. Die erhaltenen Ergebnisse werden mit der Annahme gedeutet, daß Kationendiffusion durch verschiedene innere Spinelle der geschwindigkeitsbestimmende Schritt ist.
    Notes: The oxidation of a variety of 18/8 stainless steels in high pressure CO2/2% CO has been followed in the temperature range 550-650°C using intermittent weight gain measurement metallography, fractography and scanning electron microscopy. Duplex scales formed at an early stage of oxidation. The weight gain curves were analysed in terms of a two stage process, the initial stage exponentially approaching a slower secondary stage. The primary rate of duplex scale formation did not show the usual temperature dependence. Rather a maximum in the rate was observed at ∼600°C. Secondary rates were well established at 650°C and 550°C the secondary rate at 550°C, however, being higher than that at 650°C. Various spinels occurred and the results are explained in terms of the rate controlling process being cation diffusion through different inner spinels.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 33 (1982), S. 77-82 
    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: Detaillierte Untersuchung von zwei nichtrostenden Stählen nach 20 000 Stunden Oxidation in CO2/2% CO bei hohem DruckMit Hilfe von Rasterelektronenmikroskopie, Mikrosonde und Kernmikrosonde wurden zwei Proben von 18/8-Stählen eingehend untersucht; die Proben waren repräsentativ für die beiden Extreme des nach einem parabolischen Zeitgesetz bei 600°C gewachsenen Zunders. Auf dem im Vakuum angelassenen Stahl 316 erfolgte die Zunderbildung mit hoher Geschwindigkeit, wobei innen eine vorwiegend einheitliche Spinellschicht vorlag, jedoch mit einem chromreichen und nickelarmen Spinell (geheiltes Oxid) an der Grenzfläche Metall/Zunder. Das darunter befindliche Metall war stark aufgekohlt, wobei die Kohlenstoffkonzentration in der Nähe der Metalloberfläche etwa 1 Gew.-% betrug. Bei dem Material mit geringerer Verzunderungsgeschwindigkeit war die innere Zunderschicht komplexer aufgebaut und das Metall weniger stark aufgekohlt. Die Ergebnisse werden unter Berücksichtigung der Zusammensetzung der inneren Oxidschicht und der unter Ausheilung erfolgenden Schichtbildung erläutert, wobei dem dort vorliegenden Sauerstoffpotential der geschwindigkeitsbestimmende Einfluß zugeschrieben wird.
    Notes: Detailed examination has been carried out on two specimens of 18/8 steels representing the extremes of the rates of parabolic duplex scale growth at 600°C using metallography, scanning electron microscopy, microprobe and nuclear microprobe analysis.The high growth rate material, vacuum annealed 316, had an inner layer of mainly a uniform spinel but with a chromium rich low nickel spinel (healed oxide) at the metal interface. The underlying alloy was extensively carburised with a carbon concentration near the metal surface of ∼1 wt%. The low growth rate material had a more complex inner layer and a much lower degree of carburisation. The results are explained in terms of the composition of the inner oxide and the rate of healing layer formation being controlled by the prevailing oxygen potential there.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 3827-3848 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper describes and analyzes the results of an experiment where various thin polymeric films are continuously sheared between smooth glass substrates. The shear force per unit area has been measured as a function of mean uniaxial stress and temperature using representative “good” and “poor” casting solvents followed by a range of heat treatments. The polymers studied include high density polyethylene, polybisphenol-A-carbonate, poly(ethylene terephthalate), atactic polystyrene, isotactic polystyrene, atactic poly(methyl methacrylate), isotactic poly(methyl methacrylate), poly(vinyl acetate), poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(vinyl chloride), and polytetrafluoroethylene. The results indicate that the casting solvent has a very pronounced influence upon the rheology of the film. The casting solvents may apparently confer either ductile or brittle failure in the film and also influence the nature of the temperature and pressure dependence of the shear stress. The data have been analyzed using Eyring theory and also by reference to relevant published literature on the influence of solvent and thermal treatments on the morphology and deformation behavior of polymers. “Good” solvents generally tend to promote a brittle mode of failure with little temperature dependence. The same type of solvents also produced films which have higher shear strengths and show greater increases in shear strength with pressure. These data are adequately rationalized using free volume and entanglement notions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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