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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 2939-2947 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article discusses the design and construction of guarded hot plate instruments for measuring the heat flow through an evacuated space between plane-parallel glass surfaces. In this structure, the insulating region is surrounded by two pieces of relatively highly conducting material. High resolution measurements of heat flow using these instruments therefore requires the detection of quite small temperature differences (10−4 K) between the metering piece and the guard. The instruments are calibrated, and the linearity evaluated, by measuring radiative heat transfer through the evacuated space between uncoated soda lime glass sheets; this is because this heat flow can be calculated to high accuracy from the infrared optical properties of the glass. The level of parasitic heat flow in the instruments is estimated by measuring radiative heat flow between glass surfaces coated with very low emittance layers, such as evaporated gold. These instruments operate over a range of temperatures from 0 to about 70 °C. It is shown that the heat flow between evacuated glass surfaces can be measured with these instruments to high resolution (∼10 μW) and high accuracy (∼1%) over an area of ∼1 cm2. The departures from linearity, and the level of parasitic heat flow, are within the measurement resolution. For a temperature difference across the sample of 20 K, the measurement resolution corresponds to an uncertainty in the thermal conductance of the sample of ∼0.005 W m−2 K−1. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Nuclear Inst. and Methods in Physics Research, B 47 (1990), S. 257-262 
    ISSN: 0168-583X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Optics Communications 101 (1993), S. 133-138 
    ISSN: 0030-4018
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Optics Communications 96 (1993), S. 195-201 
    ISSN: 0030-4018
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 29 (1994), S. 5794-5800 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Results are reported of the porosity and the microstructure of amorphous hydrogenated carbon films produced by direct current (d.c.) sputtering. The as-deposited films were initially slightly mesoporous. Heating the material in a vacuum, however, produced a highly porous material. The amount of porosity and the pore size distribution were directly related to the quantity of material which was outgassed during heating. The dependence on the baking temperature of the degree of sp2 hybridization in the films had the same form as the dependence of the porosity and of the quantity of outgassing. The plasmon-energy data for the films was related to the process of morphology and composition reconstruction during the heating. The outgassing quantity was strongly dependent on the oxygen content of the as-prepared material. The morphology changes in the material can be regarded as a carbon-activation process involving the incorporation of oxygen in the film during deposition, followed by the outgassing of carbon-oxygen compounds during heating in vacuum. Many of the properties of the hydrogenated amorphous carbon (a-C∶H) film were very similar to those exhibited by conventional activated carbons, and it is therefore concluded that the porous baked a-C∶H film is a form of activated carbon.
    Type of Medium: Electronic Resource
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