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  • 1985-1989  (2)
  • 1980-1984  (4)
  • 42.60B  (3)
  • Polymer and Materials Science  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Scaling and performance of CO2 lasers at supra-atmospheric pressure (1985)
    Springer
    Applied physics 37 (1985), S. 171-179 
    Details
    ISSN: 1432-0649
    Keywords: 42.55D ; 42.60B ; 58.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The performance of a compact uv photo-preionized TE laser is studied in the pressure range 1–5 bar. As the pressure is increased, the laser pulse shape is little altered, but both the peak power and the total output pulse energy increase significantly with pressure, even for constant input electrical energy. For various gas mixtures and excitation source capacitors the measurements suggest approximate output energy scaling with the product of the source charge per unit electrode area [C.m−2] and the molecular partial pressure [CO2+N2+CO]. This is explained in terms of the pressure-dependent discharge impedance. An input-energy-related discharge instability limits the optimum laser pressure to 1.5–2.5 bar, and we show that, at constant input energy, the instability boundary depends on the molecular partial pressure alone. The pre-ionization photo-electron yield varies negligibly with pressure, but the discharge tolerance to added oxygen decreases asp −3 top −4, dependent on gas mixture. Nevertheless sealed operation for 〉105 shots has been obtained with a 5% CO2∶5% CO∶3% N2∶2% H2∶85% He gas mixture at a total pressure of 5 bar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692081
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effective and simplified hybrid TEA laser design and operation (1984)
    Springer
    Applied physics 33 (1984), S. 99-101 
    Details
    ISSN: 1432-0649
    Keywords: 42.60B ; 42.55D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A compact hybrid TEA CO2 laser has been developed which, when operated with the low pressure section well below oscillation threshold, demonstrates that little cw gain is necessary to ensure single longitudinal mode (SLM) output pulses with peak power, energy and pulse shape approaching those of normal multi-mode operation. This has allowed reliable SLM operation to be obtained with a very short, wide bore rf-excited low-pressure section, making feasible simple single-mode, large-aperture TEA lasers with high peak powers and energies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688354
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    X-ray preionized CO2 laser (1985)
    Springer
    Applied physics 37 (1985), S. 219-221 
    Details
    ISSN: 1432-0649
    Keywords: 42.55D ; 33.80E ; 52.80 ; 42.60B
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A short pulse (100 ns) high-energy x-ray source has been used to preionize a transversely excited carbon dioxide gas discharge laser of 600 cm3 active volume. The maximum output power of 60 MW in a 50 ns FWHM pulse was achieved from a CO2−N2−He−CO−Xe static gas mixture at 600 Torr pressure. The energy conversion efficiency was 6%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692945
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Rheology of solvent-cast polymer films (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 3827-3848 
    Details
    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
    URL: http://dx.doi.org/10.1002/app.1983.070281222
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  • 5
    Electronic Resource
    Electronic Resource
    The oxidation of 18/8 type stainless steel in high pressure CO2/2% CO (1981)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 32 (1981), S. 1-7 
    Details
    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
    URL: http://dx.doi.org/10.1002/maco.19810320102
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  • 6
    Electronic Resource
    Electronic Resource
    The detailed examination of two stainless steel specimens oxidised for 20,000 hours in high pressure CO2/2% CO (1982)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 33 (1982), S. 77-82 
    Details
    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
    URL: http://dx.doi.org/10.1002/maco.19820330202
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    Paper (German National Licenses)
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