| 1. |
- Abdul Abas, Riad, et al.
(författare)
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Thermal Diffusivity measurement of CMSX-4 alloy by Laser flash method
- 2007
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Ingår i: International journal of thermophysics. - : Springer Science and Business Media LLC. - 0195-928X .- 1572-9567. ; 28:1, s. 109-122
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, thermal diffusivity measurements have been carried out on industrial samples of CMSX-4 nickel-base superalloy using the laser-flash method with emphasis on studying the effect of temperature and microstructure on the thermal diffusivity. The measurements were performed in the temperature range from 298 to 1623 K covering both solid as well as liquid ranges. Below 1253 K, the thermal-diffusivity values were found to increase with increasing temperature. Microstructural investigations of quenched samples revealed that below 1253 K, an ordered phase, usually referred to as the -phase was present together with the disordered fcc phase, often referred to as the γ phase. Between 1253 K and the solidus temperature, the phase was found to dissolve in the matrix alloy causing an increase in the disordering of the alloy, and thereby a small decrease in the thermal-diffusivity values. The thermal-diffusivity values of samples pre-annealed at 1573 K exhibited constancy in the temperature range from 1277 to 1513 K, which is attributed to the attainment of thermodynamic equilibrium. These equilibrium values were found to be lower than the results for samples not subjected to annealing. The thermal-diffusivity values of the alloy in the liquid state were found to be independent of temperature.
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| 2. |
- Andersson, Ove, et al.
(författare)
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Phase behavior and thermal conductivity of urea at pressures up to 1 GPa and at temperatures in the range 50–370 K
- 1994
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Ingår i: International journal of thermophysics. - : Plenum Publishing. - 0195-928X .- 1572-9567. ; 15:3, s. 513-524
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity of the solid phases I and III of urea was measured at temperatures in the range 50-370 K for pressures up to 1 GPa. Phase III, previously detected only at pressures above 0.5 GPa, was observed here at low pressures (< 0.07 GPa) below about 230 K. Extrapolation of the I-III phase line indicates that phase III might be obtained at 218 K at atmospheric pressure and, consequently, that urea might exhibit two solid phases at atmospheric pressure. The temperature dependence of the thermal conductivity of both phase I and phase III could be described by the Debye model for thermal conductivity assuming phonon scattering by three phonon umklapp processes only. Despite a volume decrease at the I --> III transition, the thermal conductivity decreased by about 20%. Normally, thermal conductivity increases at a phase transition at which volume decreases. This rather unusual behavior of urea might be due to an increase in the nearest-neighbor distance at the I --> III transition.
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| 3. |
- Andersson, Ove
(författare)
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Simulation of a glass transition in a hot-wire experiment using time-dependent heat capacity
- 1997
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Ingår i: International journal of thermophysics. - : Plenum Publishing. - 0195-928X .- 1572-9567. ; 18:1, s. 195-208
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Tidskriftsartikel (refereegranskat)abstract
- The transient hot-wire method is used for simultaneous measurements of the thermal conductivity λ and the heat capacity per unit volume ρcp and yields a peak in λ and a dip in ρcp near a glass transition. Through simulations, it is shown that these anomalous results arise due to a time dependence in cp, which is described by a fractional exponential function: cp(t) = cp(liquid) + [cp(glass) - cp(liquid)] e(-(t/τ)β), where τ is the heat capacity relaxation time and β is a sample dependent parameter (0 < β ≤ 1). By a comparison with experimental data for cyclohexanol and glycerol, it is demonstrated that this model can be used to reproduce the peak and the dip as well as the temperature at which these occur. In addition, it is shown that the maximum in λ occurs at τ = 0.3 s, whereas τ of the minimum in ρcp is dependent on β and moves from 0.4 to 1 s for a change in β from 1 to 0.5. The difference in τ between the peak and the dip is in agreement with the experimental results. It is concluded that the anomalies reveal glass forming characteristics such as a rough classification in terms of strong and fragile glass formers.
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| 4. |
- Andersson, S. Peter, et al.
(författare)
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Thermal conductivity and heat capacity per unit volume of poly(methyl methacrylate) under high pressure
- 1994
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Ingår i: International journal of thermophysics. - : Springer. - 0195-928X .- 1572-9567. ; 15:5, s. 949-962
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity and heat capacity per unit volume of poly(methyl methacrylate) (25 and 350 kg · mol−1 in molecular weight) have been measured in the temperature range 155–358 K at pressures up to 2 GPa using the transient hot-wire method. The bulk modulus has been measured up to 1.0 GPa at 294 K and yielded a constant value g = 3.4 ± 0.3 for the Bridgman parameter. No dependence on molecular weight could be detected in the properties we measured.
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| 5. |
- Andersson, S. Peter, et al.
(författare)
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Thermal conductivity, heat capacity, and compressibility of atactic poly(propylene) under high pressure
- 1997
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Ingår i: International journal of thermophysics. - : Springer Science and Business Media LLC. - 0195-928X .- 1572-9567. ; 18:3, s. 845-864
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity λ and the heat capacity per unit volume of atactic poly(propylene) have been measured in the temperature range 90–420 K at pressures up to 1.5 GPa using the transient hot-wire method. The bulk modulus has been measured in the range 200–295 K and up to 0.7 GPa. These data were used to calculate the volume dependence of λ, g=−[∂λ/λ)/(∂V/V)]T, which yielded the following values for the glassy state (T<256 K at atmospheric pressure): 3.80±0.19 at 200 K, 3.74±0.19 at 225 K, 3.90±0.20 at 250 K, 3.77±0.19 at 271 K, and 3.73±0.19 at 297 K. The resultant value for g of the liquid state was 3.61±0.15 at 297 K. Values for g which are calculated at 295 K, using theoretical models of λ(T), agree to within 12% with the experimental value for the glassy state.
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| 6. |
- Andersson, S. Peter, et al.
(författare)
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Thermal conductivity of amorphous Teflon (AF 1600) at high pressure
- 1997
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Ingår i: International journal of thermophysics. - : Springer Nature. - 0195-928X .- 1572-9567. ; 18:1, s. 209-219
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity, λ, of amorphous Teflon AF 1600 [poly(1,3-dioxole-4,5-difluoro-2,2-bis(trifluoromethyl)-co-tetrafluoroethylene)] has been measured at pressures up to 2 GPa in the temperature range 93–392 K. At 295 K and atmospheric pressure, we obtained λ=0.116 W·m−1·K−1. The bulk modulus was measured up to 1.0 GPa in the temperature range 150–296 K and the combined data yielded the following values of g=(∂ln λ/∂ln V)T :2.8±0.2 at 296 K, 3.0±0.2 at 258 K, 3.0±0.2 at 236 K, 3.4±0.2 at 200 K, and 3.4±0.2 at 150 K.
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| 7. |
- Aro, Rudolf, 1992-, et al.
(författare)
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Calibration and Uncertainty Estimation for Water Content Measurement in Solids
- 2021
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Ingår i: International journal of thermophysics. - : Springer. - 0195-928X .- 1572-9567. ; 42:3
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Tidskriftsartikel (refereegranskat)abstract
- In the field of water content measurement, the calibration of coulometric methods (e.g., coulometric Karl Fischer titration or evolved water vapor analysis) is often overlooked. However, as coulometric water content measurement methods are used to calibrate secondary methods, their results must be obtained with the highest degree of confidence. The utility of calibrating such instruments has been recently demonstrated. Both single and multiple point calibration methods have been suggested. This work compares these calibration methods for the evolved water vapor analysis technique. Two uncertainty estimation approaches (Kragten's spreadsheet and M-CARE software tool) were compared as well, both based on the ISO GUM method.
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| 8. |
- Aro, Rudolf, 1992-, et al.
(författare)
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Moisture in Solids : Comparison Between Evolved Water Vapor and Vaporization Coulometric Karl Fischer Methods
- 2020
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Ingår i: International journal of thermophysics. - : Springer. - 0195-928X .- 1572-9567. ; 41:8
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Tidskriftsartikel (refereegranskat)abstract
- Moisture content can affect the thermo-physical properties of many materials. Thus sufficient knowledge of this parameter is required to improve product shelf life and quality, reduce waste or enhance process efficiency. The traditional loss on drying methods are still the go-to methods due to their robustness and simplicity. However, their inherent lack of selectivity imposes restrictions. These are overcome with newer techniques such as vaporization coulometric Karl Fischer titration (vap-C-KFT) and evolved water vapor analysis (EWV). The former is a well-established method, but the latter was more recently introduced and the literature available on it is scarce. This work aims to bridge this gap in knowledge and demonstrate the comparability of the EWV to the more established vap-C-KFT. Multiple samples were studied and the data are analyzed along the principles reported recently by INRiM with a few modifications.
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| 9. |
- Arvizu, Miguel A, et al.
(författare)
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Influence of Thermal Annealings in Argon on the Structural and Thermochromic Properties of MoO3 Thin Films
- 2017
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Ingår i: International journal of thermophysics. - : Springer Science and Business Media LLC. - 0195-928X .- 1572-9567. ; 38:4
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Tidskriftsartikel (refereegranskat)abstract
- The effect of thermal annealing in an inert atmosphere (argon) on the structural and thermochromic properties of MoO3 thin films was investigated. MoO3 thin films were deposited by thermal evaporation in vacuum of MoO3 powders. X-ray diffraction patterns of the films showed the presence of the monoclinic Magneli phase Mo9O26 for annealing temperatures above 250 degrees C. Absorbance spectra of the films annealed in argon indicated that their thermochromic response increases with the annealing temperature in the analyzed range (23 degrees C-300 degrees C), a result opposite to the case of thermal annealings in air, for which case the thermochromic response shows a maximum value around 200 degrees C-225 degrees C and decreases for higher temperatures. These results are explained in terms of a higher density of oxygen vacancies formed upon thermal treatments in inert atmospheres.
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| 10. |
- Baird, Zachariah Steven, et al.
(författare)
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Densities, Viscosities, and Thermal Conductivities of the Ionic Liquid 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium Acetate and Its Mixtures with Water
- 2020
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Ingår i: International journal of thermophysics. - : Springer Science and Business Media LLC. - 0195-928X .- 1572-9567. ; 41:12
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Tidskriftsartikel (refereegranskat)abstract
- 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate (mTBD acetate) is a protic ionic liquid that is being investigated for use in industrial processes, such as for producing textiles from cellulose. To aid in designing such processes, we have measured the densities, viscosities, and thermal conductivities of mTBD acetate and aqueous mixtures containing mTBD acetate. We also investigated how excess amounts of mTBD or acetic acid affect the density, and found that in general an excess of either component decreases the density. However, when no water is present, the sample with excess acetic acid actually has a slightly higher density than when there is an equimolar amount of acid and base. The maximum density occurs when some water is present (around 30–40 mol%). We also modeled the density data using the ePC-SAFT equation of state and provide simple correlations for calculating the viscosity and thermal conductivity of these mixtures.
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