Thermal conductivities of molten iron, cobalt, and nickel by laser flash method

Nishi, Tsuyoshi; Shibata, Hiroyuki; Ohta, Hiromichi; Waseda, Yoshio

doi:10.1007/s11661-003-0181-2

Cited by 96 publications

(26 citation statements)

References 10 publications

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“…From this figure, one can clearly see a good reproducibility in the results. The thermal diffusivity of GaN is found to decrease with increasing temperature and it may be represented with an uncertainty of AE1:8% 13) by the following equation:…”

Section: Resultsmentioning

confidence: 99%

“…[10][11][12][13][14] The single-crystal GaN is transparent for an Nd:glass laser; hence, a thin gold layer of approximately 100 nm thickness was sputtered on both the sides of the GaN sample. One layer acts as an absorber for the pulsed laser beam and the other acts as an emitter of infrared rays.…”

Section: Thermal Diffusivity Measurementmentioning

confidence: 99%

“…The purpose of this study is to report the experimental results of thermal diffusivity of single-crystal GaN using a laser flash method [10][11][12][13] in the temperature range of 298 to 849 K. The thermal diffusivity of single-crystal SiC was also measured for the purpose of comparison. The specific heat capacity of GaN was also measured using a differential scanning calorimeter, 14) and its thermal expansion coefficient was measured by a thermal dilatometer in order to estimate the value of the thermal conductivity with sufficient accuracy.…”

Section: Introductionmentioning

confidence: 99%

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High Thermal Conductivity of Gallium Nitride (GaN) Crystals Grown by HVPE Process

et al. 2007

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A relatively large sample of gallium nitride (GaN) was grown as a single crystal using the hydride vapor phase epitaxy (HVPE) process. The thermal diffusivity of the single crystal has been measured using a vertical-type laser flash method. The thermal expansion was measured using a dilatometer in order to estimate the thermal diffusivity with sufficient reliability. The effect of sample thickness and temperature on thermal diffusivity was evaluated. The specific heat capacity of GaN was also measured by using a differential scanning calorimeter. The thermal properties of single-crystal GaN have been compared with the measured thermal properties of single-crystal silicon carbide (SiC). The thermal conductivity of single-crystal GaN at room temperature is found to be 253 AE 8:8% W/mK, which is approximately 60% of the value obtained for SiC. The excellent thermal property that is obtained in this study clearly indicates that GaN crystals are one of the promising materials for use in high-power-switching devices.

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Section: Resultsmentioning

confidence: 99%

Section: Thermal Diffusivity Measurementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High Thermal Conductivity of Gallium Nitride (GaN) Crystals Grown by HVPE Process

et al. 2007

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“…Although iron is a primary component of steel materials, for instance, high-strength steel sheets produced by thin-slab casting, there is no available data on its thermal conductivity in the molten state in a wide temperature range, including the supercooled condition. Most of the data obtained in previous studies (Touloukian et al, 1970;Ostrovskii et al, 1980;Zinovyev et al, 1986;Mills et al, 1996;Nishi et al, 2003) pertained to thermal conductivity at the melting point temperature or in a relatively narrow range of temperatures above the melting point. In this study, we numerically and experimentally investigated the effect of a static magnetic field on the thermal conductivity of molten iron measured by the EML technique.…”

Section: Introductionmentioning

confidence: 99%

Relationship between Applied Static Magnetic Field Strength and Thermal Conductivity Values of Molten Materials Measured Using the EML Technique

Baba

Sugioka

Kubo

et al. 2011

J. Chem. Eng. Japan

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IntroductionIn materials processing at high temperatures, e.g., silicon single crystal growth, precision casting of superalloy turbine blades, or precision joining, it has been well recognized that numerical simulation is an effective tool for the design and optimization of processes. Since thermophysical properties are indispensable as input data in numerical simulations, it is important to establish a method to precisely measure the thermophysical properties of high-temperature molten materials and to collect and systematize data on the thermophysical properties. The electromagnetic levitation (EML) technique has recently been used for measuring the thermophysical properties of molten materials (Egry et al., 2001). In this technique, an alternating electric current in RF coils induces an eddy current in a conductive material sample, and the sample is melted by Joule heating resulting from the current. In addition, the electromagnetic force generated by the interaction between an alternating magnetic field and the induced current lifts up the molten dropshaped material. Therefore, the containerless EML technique facilitates the precise measurement of the thermophysical properties of highly reactive molten materials, such as viscosity, density, and surface tension, over a wide temperature range even under an undercooled condition in the absence of contamination.However, it might be difficult to measure the thermal conductivity of molten materials by using the technique because magnetohydrodynamic (MHD) convection due to the electromagnetic force occurs in a molten droplet, together with buoyancy and Marangoni convection, and the flow velocity reaches 10-40 cm/s (Zong et al., 1992;Li and Song, 1998;Bojarevics and Pericleous, 2003;Hyers, 2005). Obviously, such intensive melt convection affects the thermal field in the droplet and, consequently, the measured thermophysical properties. Therefore, the thermal conductivity measured in the presence of convection is an effective thermal conductivity and is affected by convective heat transfer in addition to conduction. To measure the thermal conductivity accurately, Kobatake et al. (2007Kobatake et al. ( , 2008Kobatake et al. ( , 2010a and Fukuyama et al. (2009) have developed a novel method to measure the thermal conductivity of molten materials by the EML technique, where the measurement method is based on periodic laser heating and a static magnetic field is applied to suppress melt convection in the droplet. Using this method, they have measured the ther- Relationship between Applied Static Magnetic Field Strength and Thermal Conductivity Values of Molten Materials Measured Using the EML Technique

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“…In recent years, properties of some common aluminum, magnesium, copper, and iron alloys have been measured by several research groups (e.g., Refs. [9][10][11][12][13][14][15][16]). However, there is still a lack of reliable thermophysical property data, especially for newly developed alloys and mold materials.…”

Section: Introductionmentioning

confidence: 99%

Thermal Diffusivity of the Aluminum Alloy Al–17Si–4Cu (A390) in the Solid and Liquid States

Kaschnitz

Ebner

2007

Int J Thermophys

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The thermal diffusivity of the aluminum alloy Al-17Si-4Cu (A390) was measured in the temperature range from room temperature to 730 • C using the laser-flash technique. A commercial laser-flash system (Netzsch LFA 427) was used for the measurements. A short laser pulse of 300µs was applied to heat the bottom surface of a disk-shaped specimen, resulting in a timedependent temperature increase at the top surface. A correction for the laser pulse length as well as the surface radiation and convection was applied in order to evaluate the half time value of the temperature increase. The thermal diffusivity was calculated from the specimen thickness and the half time value. A sapphire crucible was used to contain the specimen in the mushy region and in the liquid state. As the laser is fired from below at the bottom surface of the specimen, the thickness of the melt has to be small to avoid significant buoyancy. The thermal diffusivity of the alloy above the eutectic temperature and in the liquid is drastically lower than in the solid state of the alloy.KEY WORDS: Aluminum alloy A390; Al-17Si-4Cu; high temperature; laserflash method; liquid metal; thermal diffusivity.

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Thermal conductivities of molten iron, cobalt, and nickel by laser flash method

Cited by 96 publications

References 10 publications

High Thermal Conductivity of Gallium Nitride (GaN) Crystals Grown by HVPE Process

High Thermal Conductivity of Gallium Nitride (GaN) Crystals Grown by HVPE Process

Relationship between Applied Static Magnetic Field Strength and Thermal Conductivity Values of Molten Materials Measured Using the EML Technique

Thermal Diffusivity of the Aluminum Alloy Al–17Si–4Cu (A390) in the Solid and Liquid States

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