Analysis of Different Thermal Conductivity Measurements for Al-Si Casting Alloys

2021 ◽  
Vol 1016 ◽  
pp. 1715-1721
Author(s):  
Yu Li Zhou ◽  
Gu Zhong ◽  
Zhan Kun Wang ◽  
Shi Peng Lin ◽  
Jun Chao Zhang
Keyword(s):  
Thermal Conductivity ◽  
Evaluation Model ◽  
Laser Flash ◽  
Thermal Parameter ◽  
Flash Method ◽  
Conductivity Measurements ◽  
Average Deviation ◽  
Empirical Constant ◽  
Casting Alloys ◽  
Hot Disk

Three types of methods, including Laser flash, Hot-Disk, and Wiedemann-Franz law, have been applied for thermal conductivity measurements of Al-Si casting alloys. The first two methods can obtain the thermal parameter directly for specific samples, while the third one calculates the target value by formula containing the electrical conductivity. Thus, the latter is widely used in the foundries because of its convenient and rapid characteristics. The purpose of this paper was to make a polite comparison among them and optimize the key constant C in the Wiedemann-Franz law to improve the calculation accuracy for Al-Si alloys. Measurements were conducted on the same set of specimens of Al-Si-xCu alloys (x ranges from 0.1 wt.% to 2.0 wt.%) at room temperature. The results showed that the measured value of Laser Flash method was well consistent with Hot Disk. While that of the Wiedemann-Franz law was different with them, the average deviation percentages were 2.17% and 2.36% when using empirical constant C (12.6 W/m·K) in the formula. Then, the constant C was modified to 8.4 W/ m·K and the average deviation percentage were decreased to 0.4% and 0.2% respectively. The reason for the differences was analyzed and a thermal conductivity evaluation model was proposed.

Temperature Dependency of the Effective Thermal Conductivity of Nickel Based Metal Foams

2006 ◽  
Author(s):  
Joerg Sauerhering ◽  
Oliver Reutter ◽  
Thomas Fend ◽  
Stefanie Angel ◽  
Robert Pitz-Paal
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Solid Phase ◽  
Total Porosity ◽  
Packed Bed ◽  
Laser Flash ◽  
Metal Foams ◽  
Flash Method ◽  
General Applicability ◽  
Hot Disk

This article presents experimental results of the thermal conductivity of sintered metal foams, which were manufactured by the Slip Reaction Foam Sintering (SRFS) process. For the determination of the thermal conductivity, the Transient Plane Source Technique, also known as Hot Disk, was employed. The thermal conductivity of cellular solids differs from that of their corresponding dense material. Therefore, the various pore size level effects contributing to the thermal conductivity are accounted for by introducing an effective thermal conductivity λeff. The thermal conductivity of the strut material, a sintered packed bed, was determined up to 700°C and compared to similar materials. The thermal diffusivity could also be determined by the Laser-Flash method and compared to the Hot Disk values. For the foams, λeff was determined for a total porosity of 0.85 up to 700°C. In this article, a dependency between the porosity and λeff can be shown. The linear rise of λeff up to 400°C can be due to the increase of the thermal conductivity of the solid phase. The measurements are validated by comparison of the received specific heat with values received by thermogravimetry measurements. The general applicability of the measurement method to heterogeneous materials such as metal foams is discussed and an outlook about further investigations is given.

Thermal Conductivity Measurements of Some Synthetic Al2O3-CaO-SiO2 Slags by Means of a Front-Heating and Front-Detection Laser-Flash Method

2012 ◽  
Vol 43 (6) ◽  
pp. 1405-1412 ◽  
Author(s):  
Hiroki Hasegawa ◽  
Yasuhiro Hoshino ◽  
Takeshi Kasamoto ◽  
Yuuki Akaida ◽  
Takaya Kowatari ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Flash Method ◽  
Conductivity Measurements ◽  
Front Detection

scholarly journals XVI Международная конференция "Термоэлектрики и их применения --- 2018" (ISCTA 2018), Санкт-Петербург, 8-12 октября 2018 г. Влияние неидеальности геометрической формы образца на неопределенность измерений теплопроводности методом лазерной вспышки

2019 ◽  
Vol 53 (6) ◽  
pp. 731
Author(s):  
А.В. Асач ◽  
Г.Н. Исаченко ◽  
А.В. Новотельнова ◽  
В.Е. Фомин ◽  
К.Л. Самусевич ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Measurement Uncertainty ◽  
Conductivity Measurement ◽  
Laser Flash ◽  
Comsol Multiphysics ◽  
Flash Method ◽  
Cylindrical Shape ◽  
Plane Parallel ◽  
Coefficient Of Thermal Conductivity ◽  
Truncated Cylinder

The influence of the geometric shape of the samples on the uncertainty of the coefficient of thermal conductivity measurement of materials by the method of a laser flash has been studied. Using a method of mathematical modeling in the Comsol Multiphysics software, a model that simulates the process of measuring the coefficient of thermal conductivity of samples made of graphite, Mg2Si0.4Sn0.6 and bismuth telluride using a laser flash method has been created. Samples of cylindrical shape with plane-parallel sides and samples in the form of a truncated cylinder, as well as samples in the form of a parallelepiped with a square base, were investigated. It is shown that the measurement uncertainty of samples with plane-parallel sides and sizes up to 12.7 mm, does not exceed 2%. For samples in the form of a truncated cylinder with a diameter of 3 mm and at an angle of ϕ= 1.5°, the measurement uncertainty does not exceed 3%. With an increase in the sample diameter and the ϕ angle, the measurement uncertainty increases significantly.

Study on Thermal Conductivity of Polyetheretherketone/Thermally Conductive Filler Composites

2007 ◽  
Vol 124-126 ◽  
pp. 1079-1082 ◽  
Author(s):  
Sung Ryong Kim ◽  
Dae Hoon Kim ◽  
Dong Ju Kim ◽  
Min Hyung Kim ◽  
Joung Man Park
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Carbon Fiber ◽  
Conductive Filler ◽  
Laser Flash ◽  
Flash Method ◽  
Phase System ◽  
Two Phase ◽  
Nielsen Theory ◽  
Thermally Conductive

Thermal properties of PEEK/silicon carbide(SiC) and PEEK/carbon fiber(CF) were investigated from ambient temperature up to 200°C measured by laser flash method. Thermal conductivity was increased from 0.29W/m-K without filler up to 2.4 W/m-K with at 50 volume % SiC and 3.1W/m-K with 40 volume % carbon fiber. Values from Nielsen theory that predicts thermal conductivity of two-phase system were compared to those obtained from experiment.

Laser flash method for measuring thermal conductivity of liquids. Application to molten salts

1981 ◽  
Vol 20 (4) ◽  
pp. 333-336 ◽  
Author(s):  
Yutaka Tada ◽  
Makoto Harada ◽  
Masataka Tanigaki ◽  
Wataru Eguchi
Keyword(s):  
Thermal Conductivity ◽  
Molten Salts ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Flash Method

Thermoelectric Properties of Phase Separated Composite of Ln-Doped SrTiO3 and TiO2 Micro Crystals

2007 ◽  
Vol 1044 ◽  
Author(s):  
Kiyoshi Fuda ◽  
Kenji Murakami ◽  
Shigeaki Sugiyama
Keyword(s):  
Thermal Conductivity ◽  
High Performance ◽  
Fine Particles ◽  
Bulk Material ◽  
Laser Flash ◽  
Flash Method ◽  
Helium Atmosphere ◽  
Low Thermal Conductivity ◽  
Seebeck Coefficients ◽  
Thermal Diffusivities

AbstractIt seems that no satisfactory TE property has been found in n-type oxide bulk materials even though Al-doped ZnO and La-doped SrTiO3 have high thermoelectric (TE) responses. Difficulty in developing high-performance TE materials seems to lie in finding low thermal conductivity in such oxides. The purpose of this study is to find a possibility to make an n-type TE oxide bulk material having low thermal conductivity and excellent TE properties as well. For this purpose, we fabricated and examined a series of composites constructed of TiO2 and Ln-doped SrTiO3 fine crystals. The composites were prepared via two processing steps: (1) precursor oxide preparation by wet processes; (2) sintering by using spark plasma sintering (SPS) apparatus. The microscopic structure was examined by using scanning electron microscope (SEM; HITACHI S-4500 model) attached with an energy dispersive x-ray spectroscopy. The electrical conductivities and the Seebeck coefficients were measured simultaneously using an ULVAC ZEM-1 instrument in helium atmosphere. The thermal diffusivities were measured by a laser flash method in vacuum. The composites obtained here were found to commonly have a mosaic type texture constructed of TiO2 and SrTiO3 fine particles with a typical size of 500 nm. The thermal conductivity values measured for three samples with different contents are ranged between 3 and 4 Wm-1K-1 in the temperature range from room temperature to 800 C. The values are apparently lower than the value for single crystal SrTiO3 samples presented in literature. Taking account the other TE data, e.g. Seebeck coefficient and electrical conductivity, we calculated dimensionless figure of merit, ZT, to be at maximum 0.15 at 800°C.

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