Thermal Diffusivity

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Toshimasa Hashimoto - One of the best experts on this subject based on the ideXlab platform.

  • Thermal Diffusivity of aromatic polyimide thin films by temperature wave analysis
    Journal of Applied Physics, 2009
    Co-Authors: Junko Morikawa, Toshimasa Hashimoto
    Abstract:

    The heat transport properties of aromatic polyimide thin films have become more important in the use for the electric insulation in the microelectronic devices with highly integrated circuits. The various kinds of measuring methods have been applied to obtain the anisotropic Thermal conductivity and Thermal Diffusivity of thin films, however, if the specimens are soft and transparent, the conventional methodology requires highly advanced technology in preparing the specimens for the measurement and the results obtained vary widely. The purpose of this study is to apply the temperature wave analysis (TWA) method to measure the Thermal Diffusivity of thin films and spin-coated layers of aromatic polyimide in the thickness direction at various temperatures. The TWA is an absolute method to determine the Thermal Diffusivity by using the phase shift of temperature wave. We have performed measurements on the five different chemical structures of aromatic polyimide, including polyimide isoindoloquinazolinedione ...

  • Thermal Diffusivity measurement of low k dielectric thin film by temperature wave analysis
    Thermochimica Acta, 2005
    Co-Authors: Junko Morikawa, Toshimasa Hashimoto
    Abstract:

    Abstract Thermal Diffusivity of thin film with low dielectric constant ( k ), what is called low- k dielectric thin film, 0.31–1.14 μm, including hydrogen-silsesquioxane (HSQ), methyl-silsesquioxane (MSQ), and poly(arylen ether) was examined by temperature wave analysis. The phase shift of temperature wave was observable up to 100 kHz. Thermal Diffusivity of HSQ was 4.7 × 10 −7  m 2  s −1 , on the other hand it was not higher than 1.1 × 10 −7  m 2  s −1 for MSQ or poly(arylen ether) at room temperature. Temperature dependence of Thermal Diffusivity/Thermal conductivity of MSQ was obtained, Thermal Diffusivity decreased but Thermal conductivity increased in a heating scan at 30–150 °C. It was shown that the Thermal Diffusivity of low- k thin film was correlated with the chemical and the physical structures, the latter was formed in the spin-coating and the curing process.

  • Thermal Diffusivity of binary mixture of n tricosane and n tetracosane by fourier transform temperature wave analysis
    Thermochimica Acta, 2005
    Co-Authors: Naoko Miyamoto, Junko Morikawa, Toshimasa Hashimoto
    Abstract:

    Abstract The phase transitions of binary mixtures of n -tricosane (C 23 H 48 )/ n -tetracosane (C 24 H 50 ) are investigated by Fourier transform temperature wave analysis (FT-TWA) and differential scanning calorimetry (DSC). The phase diagram determined by both methods gives a good agreement. Thermal Diffusivity shows an odd–even effect at the solid state, and the temperature dependence of Thermal Diffusivity of the mixture is classified into two types, odd-like type and even-like type, depending on the mixing ratio. The increase of Thermal Diffusivity in the rotator phase RI (orthorhombic rotator phase) prior to the phase transition to α-RII (rhombohedral rotator phase with hexagonal subcell) is found for odd number n -tricosane (C 23 H 48 ). A detailed study of the rotator phase transition is shown by the measurement of Thermal Diffusivity.

  • Thermal Diffusivity of eutectic of alkali chloride and ice in the freezing thawing process by temperature wave analysis
    Thermochimica Acta, 2005
    Co-Authors: Ningjuan Chen, Junko Morikawa, A Kishi, Toshimasa Hashimoto
    Abstract:

    Abstract Thermal Diffusivity of eutectic formed in aqueous alkali chloride solutions (NaCl, KCl, RbCl and CsCl) was determined by temperature wave analysis (TWA) during the freezing–thawing process of aqueous alkali chloride solution. An obvious change of Thermal Diffusivity in freezing–thawing processes of eutectic was observed with the super-cooling phenomena for each alkali chloride solute. The rate of Thermal Diffusivity decrease during the eutectic melting in comparison to the total decrease from the solid to the liquid state was observed larger than that of the heat of fusion measured by DSC, especially in the dilute concentration. It was confirmed that Thermal Diffusivity was sensitively influenced by the highly structure of the coexistence of eutectic crystallization and ice.

  • Thermal Diffusivity in a binary mixture of poly(phenylene oxide) and polystyrene
    Thermochimica Acta, 1995
    Co-Authors: Junko Morikawa, Aoi Kobayahi, Toshimasa Hashimoto
    Abstract:

    Abstract The Thermal Diffusivity of a binary blend of poly(phenylene oxide) and polystyrene was investigated by the AC Joule heating technique in a practical temperature range including glassy state and melt state. The temperature dependence of the Thermal Diffusivity and the glass transition temperature (Tg) of the blends were clearly observed. The single Tg, characteristic for this blend, increased with increasing the blend ratio of poly(phenylene oxide). The Thermal Diffusivity was also dependent on the blend composition.

Junko Morikawa - One of the best experts on this subject based on the ideXlab platform.

  • intercomparison of Thermal conductivity and Thermal Diffusivity methods for plastics
    Polymer Testing, 2009
    Co-Authors: Martin Rides, Junko Morikawa, Bruno Hay, Lars Halldahl, Hubert Lobo, Angela Dawson, C R G Allen
    Abstract:

    An intercomparison of measurements of the Thermal conductivity and Thermal Diffusivity of two poly(methyl methacrylates) is reported. A wide variety of methods were used: temperature wave analysis, laser flash, transient plane source (Hot Disk®), transient line-source probe, and heat flux meter methods. Very good agreement of Thermal conductivity results and, separately, of Thermal Diffusivity results was obtained. Similarly, good agreement between Thermal conductivity and Thermal Diffusivity results, when converted using specific heat capacity and density values, was also obtained. Typically, the values were within a range of approximately ±10%. Considering the significant differences between the methods and the requirements on specimen dimensions, the level of agreement between results was considered to be good.

  • Thermal Diffusivity of aromatic polyimide thin films by temperature wave analysis
    Journal of Applied Physics, 2009
    Co-Authors: Junko Morikawa, Toshimasa Hashimoto
    Abstract:

    The heat transport properties of aromatic polyimide thin films have become more important in the use for the electric insulation in the microelectronic devices with highly integrated circuits. The various kinds of measuring methods have been applied to obtain the anisotropic Thermal conductivity and Thermal Diffusivity of thin films, however, if the specimens are soft and transparent, the conventional methodology requires highly advanced technology in preparing the specimens for the measurement and the results obtained vary widely. The purpose of this study is to apply the temperature wave analysis (TWA) method to measure the Thermal Diffusivity of thin films and spin-coated layers of aromatic polyimide in the thickness direction at various temperatures. The TWA is an absolute method to determine the Thermal Diffusivity by using the phase shift of temperature wave. We have performed measurements on the five different chemical structures of aromatic polyimide, including polyimide isoindoloquinazolinedione ...

  • Thermal Diffusivity measurement of low k dielectric thin film by temperature wave analysis
    Thermochimica Acta, 2005
    Co-Authors: Junko Morikawa, Toshimasa Hashimoto
    Abstract:

    Abstract Thermal Diffusivity of thin film with low dielectric constant ( k ), what is called low- k dielectric thin film, 0.31–1.14 μm, including hydrogen-silsesquioxane (HSQ), methyl-silsesquioxane (MSQ), and poly(arylen ether) was examined by temperature wave analysis. The phase shift of temperature wave was observable up to 100 kHz. Thermal Diffusivity of HSQ was 4.7 × 10 −7  m 2  s −1 , on the other hand it was not higher than 1.1 × 10 −7  m 2  s −1 for MSQ or poly(arylen ether) at room temperature. Temperature dependence of Thermal Diffusivity/Thermal conductivity of MSQ was obtained, Thermal Diffusivity decreased but Thermal conductivity increased in a heating scan at 30–150 °C. It was shown that the Thermal Diffusivity of low- k thin film was correlated with the chemical and the physical structures, the latter was formed in the spin-coating and the curing process.

  • Thermal Diffusivity of binary mixture of n tricosane and n tetracosane by fourier transform temperature wave analysis
    Thermochimica Acta, 2005
    Co-Authors: Naoko Miyamoto, Junko Morikawa, Toshimasa Hashimoto
    Abstract:

    Abstract The phase transitions of binary mixtures of n -tricosane (C 23 H 48 )/ n -tetracosane (C 24 H 50 ) are investigated by Fourier transform temperature wave analysis (FT-TWA) and differential scanning calorimetry (DSC). The phase diagram determined by both methods gives a good agreement. Thermal Diffusivity shows an odd–even effect at the solid state, and the temperature dependence of Thermal Diffusivity of the mixture is classified into two types, odd-like type and even-like type, depending on the mixing ratio. The increase of Thermal Diffusivity in the rotator phase RI (orthorhombic rotator phase) prior to the phase transition to α-RII (rhombohedral rotator phase with hexagonal subcell) is found for odd number n -tricosane (C 23 H 48 ). A detailed study of the rotator phase transition is shown by the measurement of Thermal Diffusivity.

  • Thermal Diffusivity of eutectic of alkali chloride and ice in the freezing thawing process by temperature wave analysis
    Thermochimica Acta, 2005
    Co-Authors: Ningjuan Chen, Junko Morikawa, A Kishi, Toshimasa Hashimoto
    Abstract:

    Abstract Thermal Diffusivity of eutectic formed in aqueous alkali chloride solutions (NaCl, KCl, RbCl and CsCl) was determined by temperature wave analysis (TWA) during the freezing–thawing process of aqueous alkali chloride solution. An obvious change of Thermal Diffusivity in freezing–thawing processes of eutectic was observed with the super-cooling phenomena for each alkali chloride solute. The rate of Thermal Diffusivity decrease during the eutectic melting in comparison to the total decrease from the solid to the liquid state was observed larger than that of the heat of fusion measured by DSC, especially in the dilute concentration. It was confirmed that Thermal Diffusivity was sensitively influenced by the highly structure of the coexistence of eutectic crystallization and ice.

Tetsuya Baba - One of the best experts on this subject based on the ideXlab platform.

  • study on a Thermal Diffusivity standard for laser flash method measurements
    International Journal of Thermophysics, 2006
    Co-Authors: Megumi Akoshima, Tetsuya Baba
    Abstract:

    The National Metrology Institute of Japan (NMIJ) of AIST has been studying the laser flash method in order to establish an SI traceable Thermal- Diffusivity standard. Key technologies have been developed to reduce the uncertainty in laser flash measurements. In the present study, an uncertainty evaluation has been carried out on the laser flash measurement method in order to determine the Thermal Diffusivity value of IG-110, a grade of isotropic high-density graphite, as a candidate reference material. The Thermal Diffusivity measured by the laser flash method is derived from a specimen thickness and a heat diffusion time. And a laser flash measurement is carried out at a given temperature. The measurement system is composed of three sections corresponding to each measured quantity: length, time, and temperature. Therefore, we checked and calibrated our measurement system, and estimated the uncertainty of measurement results for the case of a grade of isotropic graphite.

  • a laser flash apparatus for Thermal Diffusivity and specific heat capacity measurements
    Journal of Thermal Analysis and Calorimetry, 2004
    Co-Authors: Kanei Shinzato, Tetsuya Baba
    Abstract:

    We have developed a laser flash apparatus for simultaneous measurements of Thermal Diffusivity and specific heat capacity of solid materials by introducing recent technical progress: uniform heating by a homogenized laser beam using an optical fiber with a mode mixer, measuring transient temperature of a specimen with a calibrated radiation thermometer, analyzing a transient temperature curve with a curve fitting method, to achieve differential laser flash calorimetry. Thermal Diffusivity, specific heat capacity and Thermal conductivity of glassy carbon and molybdenum were measured in the temperature range from 300 to 1100 K.

A Salazar - One of the best experts on this subject based on the ideXlab platform.

  • the strong influence of heat losses on the accurate measurement of Thermal Diffusivity using lock in thermography
    Applied Physics Letters, 2009
    Co-Authors: A Salazar, A Mendioroz, Raquel Fuente
    Abstract:

    In modulated photoThermal experiments the lateral Thermal Diffusivity can be obtained from the slope of the linear relation between the phase of the surface temperature and the distance to the heating spot. However, this slope is greatly affected by heat losses so that the measured Thermal Diffusivity is overestimated, especially for thin samples of poor Thermal conducting materials. In this paper we definitely identify the physical mechanism responsible for the overestimation of the Diffusivity as heat conduction to the surrounding gas. Accurate measurements of the Thermal Diffusivity using the “slope method” have been obtained by keeping the sample in vacuum.

  • Thermal Diffusivity measurements of thin plates and filaments using lock in thermography
    Review of Scientific Instruments, 2009
    Co-Authors: A Mendioroz, Raquel Fuentedacal, E Apinaniz, A Salazar
    Abstract:

    PhotoThermal radiometry has been widely used to measure the Thermal Diffusivity of bulk materials. In the case of thin plates and filaments, a one-dimensional heat propagation model including heat losses has been developed, predicting that the Thermal Diffusivity can be obtained by recording both the surface temperature amplitude and phase profile slopes (“slope method”). However, this method has given highly overestimated values of the Thermal Diffusivity of poor-conducting films and filaments. In this paper we analyze the effect of the experimental factors affecting the Thermal Diffusivity measurements of thin plates and filaments using infrared thermography, in order to establish the experimental conditions needed to obtain accurate and reliable values of the Diffusivity of any kind of material using the slope method. We present the calculations of the surface temperature of thin isotropic and anisotropic plates heated by a modulated and tightly focused laser beam, showing that the slope method is also...

  • Thermal Diffusivity measurements of thin plates and filaments using lock in thermography
    Review of Scientific Instruments, 2009
    Co-Authors: A Mendioroz, Raquel Fuentedacal, E Apinaniz, A Salazar
    Abstract:

    PhotoThermal radiometry has been widely used to measure the Thermal Diffusivity of bulk materials. In the case of thin plates and filaments, a one-dimensional heat propagation model including heat losses has been developed, predicting that the Thermal Diffusivity can be obtained by recording both the surface temperature amplitude and phase profile slopes (“slope method”). However, this method has given highly overestimated values of the Thermal Diffusivity of poor-conducting films and filaments. In this paper we analyze the effect of the experimental factors affecting the Thermal Diffusivity measurements of thin plates and filaments using infrared thermography, in order to establish the experimental conditions needed to obtain accurate and reliable values of the Diffusivity of any kind of material using the slope method. We present the calculations of the surface temperature of thin isotropic and anisotropic plates heated by a modulated and tightly focused laser beam, showing that the slope method is also valid for this kind of pointlike heating. Special attention is paid to the effect of surface heat losses (convective and radiative) on the Diffusivity measurements of small-dimension and poor-conducting materials. Lock-in thermography measurements performed in the best experimental conditions on a wide set of samples of different Thermal properties (thin isotropic and anisotropic plates and filaments) confirm the validity of the slope method to measure accurately the Thermal Diffusivity of samples of these shapes.

  • on the effective Thermal Diffusivity of fiber reinforced composites
    Applied Physics Letters, 2002
    Co-Authors: A Salazar, J M Terron, A Sanchezlavega, R. Celorrio
    Abstract:

    Modulated photoThermal techniques provide useful methods based on linear relations between measurable quantities to obtain the Thermal Diffusivity of homogeneous materials. In this letter the applicability of such linear relations in the case of unidirectional fiber-reinforced composites (UFRC) is analyzed. Based on the solution of the propagation of plane Thermal waves in a material with aligned buried cylinders, we found that the linear relation valid for homogeneous materials still holds for UFRC. However, its slope does not give the effective Thermal Diffusivity as derived from the effective Thermal conductivity measured by steady-state experiments. Anyway, as the number of cylinder rows increases the Thermal Diffusivity measured by modulated methods approaches the steady value asymptotically. The model is validated by photoThermal measurements performed on calibrated samples.

  • low temperature Thermal Diffusivity measurements of transparent solids and gases by the mirage technique
    Proceedings of the 10th international conference on photoacoustic and photothermal phenomena, 1999
    Co-Authors: A Salazar, A Sanchezlavega
    Abstract:

    In this paper we present a cryogenic mirage setup to perform Thermal Diffusivity measurements of semitransparent solids and gases in the temperature range from 77K to ambient. Collinear or perpendicular detection schemes were used to measure the Thermal Diffusivity of semitransparent solids and gases respectively. The method was validated by performing measurements on calibrated samples.

R. Celorrio - One of the best experts on this subject based on the ideXlab platform.

  • Thermal Diffusivity of rods, tubes, and spheres by the flash method
    Journal of Applied Physics, 2006
    Co-Authors: Agustín Salazar, F. Garrido, R. Celorrio
    Abstract:

    The flash method is the most used technique to measure the Thermal Diffusivity of solid samples. It consists of heating the front face of an opaque slab by a short light pulse and detecting the temperature evolution at its rear surface, from which the Thermal Diffusivity is obtained. In this paper, we extend the classical flash method to be used with rods, tubes, and spheres. First, the temperature evolution of the back surface of solid cylinders, hollow cylinders, and spheres is calculated. Then, experimental measurements of the Thermal Diffusivity on a set of stainless steel samples confirm the validity of the method.

  • on the effective Thermal Diffusivity of fiber reinforced composites
    Applied Physics Letters, 2002
    Co-Authors: A Salazar, J M Terron, A Sanchezlavega, R. Celorrio
    Abstract:

    Modulated photoThermal techniques provide useful methods based on linear relations between measurable quantities to obtain the Thermal Diffusivity of homogeneous materials. In this letter the applicability of such linear relations in the case of unidirectional fiber-reinforced composites (UFRC) is analyzed. Based on the solution of the propagation of plane Thermal waves in a material with aligned buried cylinders, we found that the linear relation valid for homogeneous materials still holds for UFRC. However, its slope does not give the effective Thermal Diffusivity as derived from the effective Thermal conductivity measured by steady-state experiments. Anyway, as the number of cylinder rows increases the Thermal Diffusivity measured by modulated methods approaches the steady value asymptotically. The model is validated by photoThermal measurements performed on calibrated samples.