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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 11 (1990), S. 315-327 
    ISSN: 1572-9567
    Schlagwort(e): ASTM C16 Committee ; insulation (thermal) ; laboratory and field measurements ; quality assurance ; reference materials ; standards ; steadystate methods ; transient methods
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The past two decades have stimulated significant growth both in thermal insulation materials and product development and in their use for new and different applications. These activities have had a resultant impact both on existing methods of measurement of relevant thermal properties and on the development of new or modified measurement techniques. Various examples of present measurement technologies applicable to the new materials and applications are discussed in relation to the current state of the art. These include (1) measurements on very high-thermal resistance per unit thickness insulation systems for appliances and buildings, (2) improvements in current standard methods of test, particularly in speed of operation and relevance to application, and (3)in situ and field measurements. The discussion includes examples of current limitations. These relate particularly to accuracy, especially at elevated temperatures, product variability, a need for relevant transient techniques, and very urgent requirements for reference materials and transfer standards. As a result, recommendations are proposed in the hope that they will stimulate necessary research and development work in the next decade.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 17 (1996), S. 253-261 
    ISSN: 1572-9567
    Schlagwort(e): flash method ; melts ; radiation correction ; slags ; three-layer analysis ; thermal conductivity ; thermal diffusivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A high-temperature measuring system has been developed to undertake measurements of thennal difusivity and specific heat up to 1900 K. The overall design allows measurements on solids to be undertaken using the accepted standard techniques and analytical procedures. The specific design for molten materials and especially slags is based on the differential threelayer technique utilizing a special cell which can be accomodated in the system. In this method, the liquid specimen is sandwiched between an upper inner platinum crucible and a lower outer platinum crucible, to provide a three-layered sandwich. A laser pulse irradiates the surface of the upper platinum crucible and the temperature response of the surface of the lower platinum crucible is observed. For the purpose of accurate measurement of specimen thickness at the measuring temperature, two runs are performed in which the thicknesses arel andl+°Dl, wherel is unknown butΔl can be set accurately with a built-in micrometer. The thermal difusivity is obtained through a curve-fitting method by a personal computer using a three-layer analysis with a correction for the radiative component based on the transparent body assumption. Following verification of the basic performance, using solids of known properties and water and ethanol, a continuous casting mixture has been evaluated. The initial results on the fluids are in good agreement with those in the literature.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 20 (1999), S. 977-986 
    ISSN: 1572-9567
    Schlagwort(e): ac calorimetry ; CVD diamond ; modified Angstrom method ; reference materials ; thermal conductivity ; thermal diffusivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Modified ac calorimetry, a variation of the Angstrom method, has been shown to be a precise tool for measuring the in-plane thermal diffusivity of thin films (thickness less than 300 μm) of a wide variety of materials and layered composites. The property is determined from an analysis of the decay curve of the ac temperature waves generated by irradiation of a specimen using uniform chopped light (at frequencies from 1 to 20 Hz) from a halogen lamp source. To address certain limiting factors, especially to improve the signal-to-noise ratio and to eliminate heat losses, an improved form of measurement instrument has been developed. It is based on the use of a modulated laser beam heating to provide a higher intensity energy source plus a special optical system to ensure that one-dimensional ac temperature wave propagation is obtained. Measurements can now be made using frequencies in the range of 0.01 to 10 Hz, i.e., 10 times lower than in the traditional method. The performance of the improved measurement instrument will be illustrated by results on various materials of known thermal properties such as nickel and stainless steel, proposed reference materials such as a glassy carbon and alumina, plus a comparison of results obtained on CVD diamond films used in an international round-robin series with those obtained by the traditional technique.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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