Transport Properties of Metals, Alloys and Their Melts From LFA Measurements

Criss, Everett M.; Hofmeister, Anne M.

doi:10.1016/b978-0-12-809981-0.00009-7

Cited by 3 publications

(12 citation statements)

References 51 publications

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“…The relatively deep penetration of blackbody emissions (from the graphite coating) also helps stimulate electronic transport. For a brief discussion of electronic and vibrational transport in metals, see [ 22 ]. Crucial points that were previously overlooked are:…”

Section: The Methods Of Laser Flash Analysismentioning

confidence: 99%

“…For most elements, D decreases with T . However, D increasing with T exists for Pd, Mn as well as many alloys [ 22 ] (Table 9.2).…”

Section: Measured Thermal Diffusivity At Ambient Pressurementioning

confidence: 99%

“…Although much data exists on metals, κ is mostly measured and sometimes this is computed from electrical resistivity using the Weidemann–Franz law, despite its known inaccuracies [ 24 ], illustrated in Figure 6 a. Additional data from [ 45 ] on Mg, Zn, Mo, Hf, Pt, Au, Ta, U show similar divergent trends [ 22 ] (Figure 9.10). Silver is apparently the only metal with a flat, linear fit.…”

Section: Measured Thermal Diffusivity At Ambient Pressurementioning

confidence: 99%

“…Direct measurements of D vs. T for elements show various behaviors consistent with a vibrational mechanism ( Figure 4 ; for details, see [ 9 , 22 ]). Importantly, (21) describes many metals, where G = 0, and so the H T term dominates.…”

Section: Measured Thermal Diffusivity At Ambient Pressurementioning

confidence: 99%

“…Despite the restrictions on electronic transport, consistent behaviors of D ele and κ ele were observed, as shown in Figure 6 b, and many other figures in [ 9 ]. The results are summarized in [ 22 ].…”

Section: Measured Thermal Diffusivity At Ambient Pressurementioning

confidence: 99%

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Dependence of Heat Transport in Solids on Length-Scale, Pressure, and Temperature: Implications for Mechanisms and Thermodynamics

Hofmeister

2021

Materials

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Accurate laser-flash measurements of thermal diffusivity (D) of diverse bulk solids at moderate temperature (T), with thickness L of ~0.03 to 10 mm, reveal that D(T) = D∞(T)[1 − exp(−bL)]. When L is several mm, D∞(T) = FT−G + HT, where F is constant, G is ~1 or 0, and H (for insulators) is ~0.001. The attenuation parameter b = 6.19D∞−0.477 at 298 K for electrical insulators, elements, and alloys. Dimensional analysis confirms that D → 0 as L → 0, which is consistent with heat diffusion, requiring a medium. Thermal conductivity (κ) behaves similarly, being proportional to D. Attenuation describing heat conduction signifies that light is the diffusing entity in solids. A radiative transfer model with 1 free parameter that represents a simplified absorption coefficient describes the complex form for κ(T) of solids, including its strong peak at cryogenic temperatures. Three parameters describe κ with a secondary peak and/or a high-T increase. The strong length dependence and experimental difficulties in diamond anvil studies have yielded problematic transport properties. Reliable low-pressure data on diverse thick samples reveal a new thermodynamic formula for specific heat (∂ln(cP)/∂P = −linear compressibility), which leads to ∂ln(κ)/∂P = linear compressibility + ∂lnα/∂P, where α is thermal expansivity. These formulae support that heat conduction in solids equals diffusion of light down the thermal gradient, since changing P alters the space occupied by matter, but not by light.

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Section: The Methods Of Laser Flash Analysismentioning

confidence: 99%

“…For most elements, D decreases with T . However, D increasing with T exists for Pd, Mn as well as many alloys [ 22 ] (Table 9.2).…”

Section: Measured Thermal Diffusivity At Ambient Pressurementioning

confidence: 99%

Section: Measured Thermal Diffusivity At Ambient Pressurementioning

confidence: 99%

Section: Measured Thermal Diffusivity At Ambient Pressurementioning

confidence: 99%

Section: Measured Thermal Diffusivity At Ambient Pressurementioning

confidence: 99%

See 3 more Smart Citations

Dependence of Heat Transport in Solids on Length-Scale, Pressure, and Temperature: Implications for Mechanisms and Thermodynamics

Hofmeister

2021

Materials

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Analysis of thermo-physical properties of NiCr HVOF coatings on T24, T92, VM12 and AISI 304 steels

Abu-warda

Boissonnet

López

et al. 2021

Surface and Coatings Technology

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Thermal runaway criterion as a basis for the protection of high-temperature superconductor magnets

Marchevsky,

Prestemon

2024

Supercond. Sci. Technol.

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High-temperature superconductor (HTS) based high-field magnet systems are essential for particle accelerators and fusion energy applications. Quench protection of such magnets is difficult owing to a slow quench propagation velocity in HTS. While in conventional NbTi and Nb3Sn-based magnets, a normal zone expands typically quickly, and the stored energy is dissipated across a large volume of the windings, a normal zone in an HTS magnet propagates slowly and, thus, can heat up quickly to high temperatures destroying the conductor. At the same time, growing experimental evidence suggests that HTS conductors can operate in a stable dissipative flux flow regime for a substantial range of operational currents before entering an irreversible thermal runaway. Therefore, a new protection paradigm for HTS magnets has emerged, aiming to prevent quenching, using advanced diagnostics to detect the dissipative regime onset. In the present paper, we propose a simple criterion for the thermal runaway in HTS conductors and calculate allowable temperature margins within which an HTS magnet can be operated safely. Outside of those temperature margins, a common quench integral approach may be used to estimate the upper boundary of the time margin for activating the protection system. We verify the applicability of our approach by comparing the calculated runaway conditions for a Bi-2223 conductor with the experimentally measured values. The thermal and time margins can define the quench protection system's requirements for implementing the quench-avoiding protection paradigm. 

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Transport Properties of Metals, Alloys and Their Melts From LFA Measurements

Cited by 3 publications

References 51 publications

Dependence of Heat Transport in Solids on Length-Scale, Pressure, and Temperature: Implications for Mechanisms and Thermodynamics

Dependence of Heat Transport in Solids on Length-Scale, Pressure, and Temperature: Implications for Mechanisms and Thermodynamics

Analysis of thermo-physical properties of NiCr HVOF coatings on T24, T92, VM12 and AISI 304 steels

Thermal runaway criterion as a basis for the protection of high-temperature superconductor magnets

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