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  • Articles: DFG German National Licenses  (6)
  • 1990-1994  (6)
  • 1990  (6)
  • Polymer and Materials Science  (6)
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  • Articles: DFG German National Licenses  (6)
Material
Years
  • 1990-1994  (6)
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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 21 (1990), S. 93-104 
    ISSN: 0933-5137
    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: Understanding the relationships between mechanical and other physico-chemical properties and the microstructural chemistry is a necessity for a well-controlled development of new materials. A prerequisite for the achievement of this goal is an advanced microanalytical characterization, which can be obtained by application of surface analysis methods. Among these, high resolution Auger electron spectroscopy (HR-AES or Scanning Auger Microscopy, SAM) has proved to be extremely useful for surface, interface and depth profile analysis of ceramic materials. After a short presentation of the principles and the main areas of application, specific advantages are discussed for some examples. Those are e.g. a depth of information in the nanometer range, a sub-micrometer lateral resolution, a relatively high detection sensitivity for the light elements like B, C, N, O, and a small matrix effect in quantitative analysis. The main disadvantages are due to a variety of detrimental electron beam induced effects which are outlined for some examples of oxide and non-oxide ceramics. The generation of electrical charging of insulating ceramics and its avoidance or reduction by appropriate experimental procedures is particularly emphasized.
    Notes: Das für eine kontrollierte Materialentwicklung benötigte Verständnis des Zusammenhangs zwischen mechanischen und anderen physikalisch-chemischen Eigenschaften und dem mikrostrukturellen Aufbau setzt eine leistungsfähige mikroanalytische Charakterisierung voraus, die vor allem durch den Einsatz oberflächenspezifischer Untersuchungsverfahren erhalten werden kann. Unter diesen hat sich insbesondere die hochauflösende Auger-Elektronenspektroskopie (High Resolution Auger-Electron Spectroscopy, HR-AES bzw. Scanning Auger Microscopy, SAM) in Verbindung mit Oberflächen-, Bruchflächen- und Tiefenprofilanalysen bewährt, deren Grundlagen und Haupteinsatzgebiete unter besonderer Berücksichtigung keramischer Werkstoffe vorgestellt werden. Den Vorteilen kleiner Informationstiefe im Nanometerbereich, der hohen Ortsauflösung im Sub-Mikrometer-Bereich, der vergleichsweise hohen Nachweisempfindlichkeit für leichte Elemente wie B, C, N, O sowie der geringen Matrix-Effekte bei der quantitativen Analyse stehen als Nachteile eine Reihe störender elektronenstrahlinduzierter Effekte gegenüber. Diese werden anhand ausgewählter Beispiele für oxidische- und nichtoxidische Keramiken erläutert, wobei besondere Betonung auf die Entstehung von elektrischen Aufladungen bei nichtleitenden Keramiken und deren Vermeidung bzw. Verminderung durch geeignete experimentelle Maßnahmen gelegt wird.
    Additional Material: 14 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 41 (1990), S. 756-760 
    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: Oxidationsverhalten von Hartstoffschichten aus CrNx und (Cr,Al)NxDurch reaktives Magnetron-Sputtering hergestellte Nitrid-Hartstoffschichten aus CrNx und (Cr,Al)Nx wurden in Luft bei Temperaturen zwischen 500°C und 900°C bis zu 16 Stunden lang oxidiert. Ursprüngliche und oxidierte Proben wurden durch Auger-Elektronenspektroskopie, Rasterelektronenmikroskopie und Röntgenbeugung untersucht. Die Ergebnisse zeigen, daß die Oxidation von Beschichtungen aus CrNx durch das Wachstum einer Chromoxidschicht gekennzeichnet ist, das durch Diffusion von Cr aus der Nitridschicht bestimmt wird. Unterhalb der Oxidschicht entsteht eine an Cr verarmte und mit N angereicherte Schicht. Beschichtungen mit dem ternären (Cr,Al)Nx sind bei allen Temperaturen zwischen 500°C und 900°C etwa fünfmal mehr oxidationsbeständig, als solche aus CrNx. Die Oxidschicht auf (Cr,Al)Nx zeigt eine ausgeprägte Variation der Zusammensetzung mit der Tiefe. Diese kann im wesentlichen durch das Vorherrschen einer äußeren Cr-reichen (Cr,Al)-Oxidschicht gedeutet werden, die sich nach innen zu in einer Al-angereicherten (Cr,Al)-Oxynitridschicht fortsetzt. Im Gegensatz zu CrNx findet man eine breite Interdiffusionszone von N und O. In beiden Fällen wird der Oxidationsvorgang hauptsächlich durch die Diffusion von Cr bestimmt.
    Notes: Reactively magnetron-sputtered CrNx and (Cr,Al)Nx hard costings were oxidized in air at temperatures between 500°C and 900°C for periods up to 16 h. The original and the oxidized samples were characterized by scanning electron microscopy, X-ray diffraction and scanning Auger electron spectroscopy. The results show that CrNx coatings oxidize by growth of chromium oxide layer on top of the coating governed by outward diffusion of Cr. Below the oxide layer, a Cr-depleted and N-enriched intermediate nitride layer is left. The ternary (Cr,Al)Nx nitride coating is about five times more oxidation resistant than CrNx at all temperatures between 500°C and 900°C. The oxide layer on (Cr,Al)Nx shows a strong variation in composition with depth, which can be interpreted as a main oxide layer of a Cr-rich (Cr,Al) oxide followed by an Al-enriched (Cr,Al) oxynitride. In contrast to CrNx, a wide interdiffusion zone of N and O is found. In both cases the oxidation process is mainly controlled by Cr diffusion.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 15 (1990), S. 794-796 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Sputter-deposited multilayers of Si and Ta with a nominal period length of a double layer (Ta + Si) of 20 nm were studied with AES depth profiling and with transmission electron microscopy (TEM). The asymmetric shape of the measured Si layer profiles was fitted to model calculations based on preferential sputtering of Si and an atomic mixing zone length of 4 nm for 3 keV Ar+ ions at a 36° incidence angle. TEM images of cross-sections of the original sample show sharp Si/Ta and Ta/Si interfaces, with a width of ∼ 0.5 nm. The atomic mixing zone length of the sputter-profiled sample was observed directly by TEM and was determined to be 4.0 nm, in accordance with the AES profile evaluation. It is concluded that the observed asymmetric broadening of the shape of the measured AES sputtering profiles is due mainly to atomic mixing and is enhanced by preferential sputtering of Si.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 16 (1990), S. 546-551 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: AES of in situ fractured bicrystals of an Fe-4 at.% Si alloy containing traces of phosphorus was used to study the temperature dependence of the segregation at the symmetrical {112} (coherent twin) grain boundary between 773 and 1173 K. The observed enrichment of P decreases with temperature, whereas that of Si increases slightly. This behaviour is described by a mutual repulsive interaction coefficient α′ = 92 kJ mol-1 of P and Si and the corre-sponding pure binary segregation enthalpies ΔH0P = -7.9 kJ mol-1 and ΔH0Si = -3.0 kJ mol-1, the absolute values of which are considerably lower than those reported for polycrystalline samples of Fe—P and Fe—Si. The differences are explained on the basis of orientation, concentration and interaction effects.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 16 (1990), S. 563-564 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 16 (1990), S. 335-336 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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