Normal Spectral Emissivity at a Wavelength of 684.5 nm and Thermophysical Properties of Solid and Liquid Molybdenum

Polarimetric emissivity measurements adapted for a rapid pulse heating setup and recent results of normal spectral emissivity at 684.5 nm for molybdenum at melting and in the liquid phase are presented. Also reported is a complete set of thermophysical data (specific enthalpy, isobaric heat capacity, electrical resistivity, thermal conductivity, and thermal diffusivity) for molybdenum for both solid and liquid states. The results for all mentioned thermophysical properties are discussed and furthermore compared to literature values. The normal spectral emissivity and the electrical resistivity of molybdenum show opposite trends in the liquid phase, leading to the conclusion that a prediction of normal spectral emissivity at the given wavelength of 684.5 nm based on the Hagen–Rubens-relation and electrical resistivity measurements is not applicable.     

Measurement and Analysis of Thermophysical Properties of Diorites in the Temperature Range from 253 to 333 K

Thermal conductivity and thermal diffusivity are simultaneously measured for a collection of diorite samples taken from Shewa-Shahbaz Garhi volcanic complex near Mardan, Pakistan by using the transient plane source (TPS) technique. The temperature dependence of the transport properties of these samples is studied in the temperature range from 253 to 333 K. Different relationships for the temperature dependence of the thermal conductivity and thermal diffusivity are tested. The samples are also characterized by their chemical composition, density, porosity, and specific gravity at room temperature and atmospheric pressure. Theoretical calculation of the specific gravity parameter based on the chemical composition is in good agreement with the experimental observation. No correlation was found for the temperature dependence of the thermal transport behavior on porosity, chemical composition, and density.     

Thermophysical Properties of Swine Myocardium

This paper presents the experimental technique and results for the thermal conductivity, thermal diffusivity, and density of swine myocardial tissue. These properties were measured for freshly excised tissue. Thermal properties were measured using a self-heated thermistor probe, while the density was measured using a water displacement method. Thermistor probes were inserted into the tissue of interest and were used to supply heat within the tissue as well as to monitor the temperature rise in the tissue. An empirical calibration procedure was used to measure the properties of the tissue at different temperatures. The measurement instrument was first calibrated against agar-gelled water and glycerol at each temperature. The measurements were made at temperatures of 25, 37, 50, 62, and 76°C. The uncertainty in the measurement ranges from 2% at lower temperatures to about 5% at higher temperatures (T > 50°C). The properties of the tissue depend significantly on the water content. At temperatures higher than 50°C, there is significant water loss from the tissue during the procedure. The water loss is found to vary exponentially with the increase in temperature relative to ambient. Consequently, there is a decrease in the thermal conductivity values with increasing temperature. This decrease, however, is not as much as one would expect from the water loss data. A hypothesis to explain the relationships among water loss, cell damage, and thermal properties is proposed.     

Japanese research on thermophysical properties of solids

The research activities on thermophysical properties in many engineering fields in Japan have been promoted for the past 10 years. In this paper, the outlook is reviewed on recent research work on thermophysical properties, mainly on thermal conductivity and thermal diffusivity of solids, in Japan. The research activities are described in such areas as measuring methods, metals, nuclear fuels and ceramics, building materials and insulators, soils and rocks, energy storage materials and compound materials, and dispersed materials.Presented at the Japan-United States Joint Seminar on Thermophysical Properties, October 24–26, 1983, Tokyo, Japan.     

Proton Irradiation Effects on Thermophysical Properties of High-Thermal-Conductivity Graphite Sheet for Spacecraft Application

This paper describes an evaluation of the proton irradiation effects on the thermal characteristics of a pyrolytic graphite sheet (PGS), which has characteristics of high thermal conductivity, light weight, and flexibility, in order to apply this material to an advanced spacecraft thermal control device, the reversible thermal panel (RTP). The results show slight changes in the in-plane thermal diffusivity and total hemispherical emittance of the PGS for 2.0 MeV proton irradiation. An RTP prototype model based on the PGS was designed and fabricated, and its thermal performance was evaluated. The effects of changes in thermal characteristics of the PGS on the thermal performance of the RTP were also discussed.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–26, 2004, Hefei and Huangshan, Anhui, P. R. China.     

4He Thermophysical Properties: New Ab Initio Calculations

Since 2000, atomic physicists have reduced the uncertainty of the helium-helium “ab initio” potential; for example, from approximately 0.6 % to 0.1 % at 4 bohr, and from 0.8 % to 0.1 % at 5.6 bohr. These results led us to: (1) construct a new inter-atomic potential ϕ₀₇, (2) recalculate values of the second virial coefficient, the viscosity, and the thermal conductivity of ⁴He from 1 K to 10,000 K, and (3), analyze the uncertainties of the thermophysical properties that propagate from the uncertainty of ϕ₀₇ and from the Born-Oppenheimer approximation of the electron-nucleon quantum mechanical system. We correct minor errors in a previous publication [J. J. Hurly and M. R. Moldover, J. Res. Nat. Inst. Standards Technol. 105, 667 (2000)] and compare our results with selected data published after 2000. The ab initio results tabulated here can serve as standards for the measurement of thermophysical properties.     

Evaluation of Thermophysical Properties of Functionally Graded Materials

In this work, by considering four-layered functionally graded material (FGM) specimens of Cu/Ni and PSZ/NiCrAlY, the transient characteristics and homogeneity of heat conduction media have been studied. The thermal diffusivities of the considered specimens have been measured by the laser flash method. As the temperature response curve of a FGM is very similar to that of a homogeneous material, it is difficult to distinguish a FGM from a homogeneous material by the shape of the temperature responses. Therefore, the thermal diffusivity obtained from the half-time method is usually taken as the corresponding value of the thermal diffusivity. The apparent thermal conductivity, obtained from the corresponding value of the thermal diffusivity and the average of the heat capacity of each layer, is different from the effective thermal conductivity, obtained from the sum of the heat resistances of each layer. As the values of the heat capacity of materials exist over a certain range, and the heat capacity distribution can be predicted when the materials in a FGM are known, the amount of error that will be caused when the effective thermal conductivity is replaced by the apparent value can be determined. Also, the heterogeneity of a FGM, based on an evaluation of thermophysical properties, has been discussed.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui,P. R. China.     

Determination of Thermophysical Properties for Polymer Films using Conduction Analysis of Laser Heating

Determination of the thermophysical properties of thin film materials is important for modeling and optimizing laser microvia drilling of organic substrates in microelectronics applications. Techniques to measure the density, thermal conductivity, thermal diffusivity, thermal decomposition point, and specific ablation heat of thin polymer films are described. An experimental apparatus was set up for laser heating of the sample. To measure the thermal diffusivity, an analytic heat transfer model is developed. One-dimensional heat conduction is assumed due to the small thickness of the film compared to the radius of the laser beam. The value of thermal diffusivity is obtained by fitting the experimental data to the theory. The specific ablation heat is obtained by measuring the mass loss during laser ablation. The experimental apparatus and the property determination methodology can also be applied to thin samples of other materials.     

Absolute Measurement of Thermophysical and Optical Thin-Film Properties by Photothermal Methods for the Investigation of Laser Damage

Perspectives and limits of the application of the photothermal technique are given for the measurement of absorption, thermal, and thermoelastic properties in thin films. The peculiarities of this technique in the frequency and time domains are discussed in some detail, and selected important results with respect to laser damage studies in optical coatings are pointed out. Emphasis is placed on the absolute measurement of both optical and thermophysical properties in dielectric materials in thin-film form and, also, on the influence of both absorption and changed thermal properties in thin films on their thermally induced laser damage resistance.     

Intercomparison of Measurements of the Thermophysical Properties of Polymethyl Methacrylate

Results of an intercomparison of measurements of thermal conductivity, thermal diffusivity, specific heat capacity, and density of polymethyl methacrylate (PMMA) in the temperature range between –70°C and +80°C are presented. The purpose of this comparison is to investigate the variability of the results among guarded hot-plate (GHP) and guarded heat-flow meter (GHF) techniques on the one hand and among GHP/GHF and other measuring instruments on the other. The primary objectives are to characterize the material properties mentioned and to quantify the effects of thermal contact resistances and temperature measurements. With regard to future use of PMMA as a reference material, reference data for the thermal conductivity are derived.     

Ab Initio Values of the Thermophysical Properties of Helium as Standards

Recent quantum mechanical calculations of the interaction energy of pairs of helium atoms are accurate and some include reliable estimates of their uncertainty. We combined these ab initio results with earlier published results to obtain a helium-helium interatomic potential that includes relativistic retardation effects over all ranges of interaction. From this potential, we calculated the thermophysical properties of helium, i.e., the second virial coefficients, the dilute-gas viscosities, and the dilute-gas thermal conductivities of ³He, ⁴He, and their equimolar mixture from 1 K to 10⁴ K. We also calculated the diffusion and thermal diffusion coefficients of mixtures of ³He and ⁴He. For the pure fluids, the uncertainties of the calculated values are dominated by the uncertainties of the potential; for the mixtures, the uncertainties of the transport properties also include contributions from approximations in the transport theory. In all cases, the uncertainties are smaller than the corresponding experimental uncertainties; therefore, we recommend the ab initio results be used as standards for calibrating instruments relying on these thermophysical properties. We present the calculated thermophysical properties in easy-to-use tabular form.     

Thermophysical Properties of Multi-Walled Carbon Nanotube-Reinforced Polypropylene Composites

The thermal conductivity and thermal diffusivity of chemically surface-treated multi-walled carbon nanotube (MWCNT) reinforced polypropylene (PP) composites were measured using the 3ω method in the temperature range of 90–320 K and photoacoustic (PA) spectroscopy at room temperature, respectively. Nine kinds of samples were prepared by the melt-blending of PP resins with the addition of 0.1, 0.5, and 2.0 mass% of non-treated, nitric acid (HNO₃)-treated, and potassium hydroxide (KOH)-treated nanotube contents, and compression-molded at 180°C into about 0.5 mm thickness composite films using the hot-press. The measured thermal conductivities are in the range from 0.05 to 0.6 W ·m⁻¹·K⁻¹ and increase as the temperature increases and the CNT concentrations are increased. By the chemical treatment, the thermal conductivity of 0.5 and 2.0 mass% samples were enhanced by about a factor of two; however, the sample of 0.1 mass% did not change. This can be explained qualitatively by the effects of chemical treatment on the reinforcing ability for CNTs/polymer composites.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, Hefei and Huangshan, Anhui, P. R. China.     

Thermophysical Properties of Solid and Liquid Ti-6Al-4V (TA6V) Alloy

Ti-6Al-4V (TA6V) titanium alloy is widely used in industrial applications such as aeronautic and aerospace due to its good mechanical properties at high temperatures. Experiments on two different resistive pulse heating devices (CEA Valduc and TU-Graz) have been carried out in order to study thermophysical properties (such as electrical resistivity, volume expansion, heat of fusion, heat capacity, normal spectral emissivity, thermal diffusivity, and thermal conductivity) of both solid and liquid Ti-6Al-4V. Fast time-resolved measurements of current, voltage, and surface radiation and shadowgraphs of the volume have been undertaken. At TU-Graz, a fast laser polarimeter has been used for determining the emissivity of liquid Ti-6Al-4V at 684.5 nm and a differential scanning calorimeter (DSC) for measuring the heat capacity of solid Ti-6Al-4V. This study deals with the specific behavior of the different solid phase transitions (effect of heating rate) and the melting region, and emphasizes the liquid state (T > 2000 K).     

Thermophysical Properties of Thermal Sprayed Coatings on Carbon Steel Substrates by Photothermal Radiometry

Laser infrared photothermal radiometry (PTR) was used to measure the thermophysical properties (thermal diffusivity and conductivity) of various thermal sprayed coatings on carbon steel. A one-dimensional photothermal model of a three-layered system in the backscattered mode was introduced and compared with experimental measurements. The uppermost layer was used to represent a roughness-equivalent layer, a second layer represented the thermal sprayed coating, and the third layer represented the substrate. The thermophysical parameters of thermal sprayed coatings examined in this work were obtained when a multiparameter-fit optimization algorithm was used with the backscattered PTR experimental results. The results also suggested a good method to determine the thickness of tungsten carbide and stainless-steel thermal spray coatings once the thermophysical properties are known. The ability of PTR to measure the thermophysical properties and the coating thickness has a strong potential as a method for in situ characterization of thermal spray coatings.     

Thermophysical Properties of Heterogeneous Structures Measured by Pulse Transient Method

This paper discusses differences in thermophysical parameters (thermal conductivity λ, thermal diffusivity a, and specific heat c) that can be found when experimental methods with different measuring regimes are used. Two classes of methods are compared, namely, classical methods using steady-state, equilibrium, and dynamic measuring regimes and transient methods. The data consistency formula λ = acρ gives a picture on data reliability when single-parameter methods are used. Results of analysis are verified on published, recommended, and measured data by transient methods considering homogenous materials (stainless steel A 310, BK 7, Perspex) and heterogeneous materials (composite C/C–SiC, aerated autoclaved concrete). Satisfactory agreement on data for the thermophysical parameters was found on homogenous materials only. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

Thermophysical Properties of 1,1,1,3,3-Pentafluorobutane (R365mfc)

This paper presents an experimental study on various thermophysical properties of a new fluoroalkane, 1,1,1,3,3-pentafluorobutane (R365mfc). The thermal conductivity of R365mfc was measured in the liquid phase near saturation conditions at temperatures between 263 and 333 K using a parallel plate instrument with an uncertainty of less than ±5%. For the measurement of the saturated liquid density between 273 and 353 K, a vibrating tube instrument was used. The uncertainty of the density measurements is less than ±0.1%. In addition, experimental data have been obtained for R365mfc under saturation conditions over a wide temperature range from about 253 to 460 K using light scattering techniques. Light scattering from the bulk fluid has been applied for measuring both the thermal diffusivity and the sound speed in the liquid and vapor phases. Light scattering by surface waves on a horizontal liquid–vapor interface has been used for the simultaneous determination of the surface tension and kinematic viscosity of the liquid phase. With the light scattering techniques, uncertainties of less than ±1.0, ±0.5, ±1.0, and ±1.2% have been achieved for the thermal diffusivity, the sound speed, the kinematic viscosity, and the surface tension, respectively.     

透水沥青混合料的热物特性与热阻功能

为研究透水沥青混合料的热物性,基于热力学理论计算比较了透水沥青混合料和密级配沥青混合料的热导率、比热容、热扩散率等指标,并对透水沥青混合料的热物性指标与空隙率、含水率的关系展开分析;通过设计室内光照试验,测得相同的传热条件下两种材料表面和底部的温度变化。理论计算结果表明同密级配沥青混合料相比,透水沥青混合料的热导率降低约20%,热扩散率降低约10%;室内温度测试结果显示,透水沥青混合料试件表面较密级配沥青混合料试件温度低2～2.5℃,底部温度低3～3.5℃,说明透水沥青混合料具有热阻功能,对气温荷载变化的抵抗能力较强,验证了理论计算结果。     

Thermophysical Properties of Solid Phase Zirconium at High Temperatures

This paper presents experimental results on the thermophysical properties of relatively pure polycrystalline zirconium samples in the solid phase from room temperature up to near the melting point. The specific heat capacity and specific electrical resistivity were measured from 290 to 1970 K, the hemispherical total emissivity from 1400 to 2000 K, the normal spectral emissivity from 1480 to 1940 K, and the thermal diffusivity in the range from 290 to 1470 K. From these data, the thermal conductivity and Lorentz number were computed in the range from 290 to 1470 K. For necessary corrections the most recent values of the linear thermal expansion from the literature have been used. Subsecond pulse calorimetry for measuring heat capacity, specific electrical resistivity, and both emissivities and the laser flash method for measuring thermal diffusivity were applied. Samples in the form of a thin rod and in the form of a thin disk were used in the first and second methods, respectively. Measurement uncertainties were generally about 3% for heat capacity, 1.6% for specific electrical resistivity, 3–10% for the two emissivities, and from less than 1% up to 6% for thermal diffusivity. All the results are discussed in reference to available literature data.Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

Simultaneous Measurement of Thermophysical Properties and Dielectric Properties of PZT-Based Ferroelectric Ceramics by Thermal Radiation Calorimetry

Simultaneous measurements of thermophysical properties and dielectric properties have been performed for PZT-based ferroelectric ceramics. An apparatus based on thermal radiation calorimetry was used in the present measurements. Anomalies in the thermophysical properties were observed near the ferroelectric-to-paraelectric phase transition temperature. The anomalous peak was at almost the same temperature as the inflection point of the dielectric constant. It was found that modification of PZT with increasing Nb, Mg, Zn, and Sr causes a decrease of the Curie temperature and an increase of the hysteresis phenomena for the phase transition, and the values of the thermal conductivity increase with temperature similar to amorphous materials.     

An Investigation of the Thermophysical Properties of a Liquid in a Flow Using the Method of Pulse Heating

The theoretical principles are described of measuring the thermophysical properties of a liquid in a flow during a short pulse of heating a quick-response probe. A plane probe and a linear probe are used to measure the thermal activity, thermal conductivity, thermal diffusivity, and kinematic viscosity of some liquids at different velocities of flow.