scholarly journals Thermal conductivity measurement of infrared optical fibers based on silver halide solid solution crystals

2021 ◽  
Vol 2127 (1) ◽  
pp. 012052
Author(s):  
A Turabi ◽  
B P Zhilkin ◽  
L V Zhukova ◽  
A S Shmygalev ◽  
A V Rudenko ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Solid Solution ◽  
Optical Fibers ◽  
Thermal Conductivity Coefficient ◽  
Silver Halide ◽  
Conductivity Measurement ◽  
Laser Flash ◽  
Flash Method ◽  
Production Technologies ◽  
Light Guides

Abstract The aim of the study is to measure the thermal conductivity of silver halide light guides based on crystals of the AgCl-AgBr system used in PSD production technologies. The conductivity temperature coefficient of the samples under study were determined by the laser flash method using the LFA 467 (Hyper Flash) installation. We studied mono- and polycrystalline samples of solid solutions with the composition AgCl0,25AgBr0,75 in the temperature range 298–523 K. The thermal conductivity of the investigated materials was then calculated using literature data on density and heat capacity. The thermal conductivity coefficient ranges from 0.80±0,04 to 0.53±0,03 (W/mK), depending on the microstructure of the sample.

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.

Application of Norbury Rule to Thermal Conductivity in Intermetallic Compounds

1994 ◽  
Vol 364 ◽  
Author(s):  
Yoshihiro Terada ◽  
Tetsuo Mohri ◽  
Tomoo Suzuki
Keyword(s):  
Thermal Conductivity ◽  
Solid Solution ◽  
Intermetallic Compounds ◽  
Room Temperature ◽  
Laser Flash ◽  
Flash Method ◽  
Horizontal Distance ◽  
Conductivity Data ◽  
Host Metal ◽  
Thermal Conductivity Λ

AbstractThermal conductivity data at room temperature, which are measured by laser-flash method, are presented in B2 aluminides and titanides, and in nickel based L12 compounds. The thermal conductivity λ is changed in the following order of the compounds. λ(NiAl) >λ(CoAl)>λ(FeAl), λ(NiTi)<λ(CoTi)<λ(FeTi), λ(Ni3Al)>λ(Ni3Si) and λ(Ni3Ga)>λ(Ni3Ge). According to Norbury rule originally proposed for the concentration dependence of electrical resistivity, the increasing rate is greater in the solid solution, where the position of solute elements is more remote in horizontal distance from a host metal in the periodic table. It is found that this rule holds for the thermal conductivity measured for the intermetallic compounds with the combination of a series of guest constituents and a fixed host constituent both in the B2 and Ll2 intermetallic compounds.

scholarly journals Thermal Conductivity Measurement Method for the Thin Epoxy Adhesive Joint Layer

2021 ◽  
Vol 39 (4) ◽  
pp. 402-408
Author(s):  
Da-In Lim ◽  
So-Jeong Lee ◽  
Seung-Boo Jung ◽  
Jun-Ki Kim
Keyword(s):  
Thermal Conductivity ◽  
Adhesive Joint ◽  
Conductivity Measurement ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Thermal Conductivity Measurement ◽  
Flash Method ◽  
Hot Plate ◽  
Plate Method ◽  
Guarded Hot Plate

Epoxy adhesives, particularly for non-conductive pastes, are used in 3D chip-stack flip-chip packages to reinforce the mechanical strength of joints. Although the thickness of the adhesive layer is relatively small, its thermal conductivity is known to have a major effect on the heat dissipation behavior of chipstack packages. Because conventional thermal conductivity measurement methods such as the laser flash method are based on the bulk specimens having thicknesses greater than several mm, they are limited in their ability to measure the thermal conductivity of thin adhesive layers between silicon dies. In this study, a modified guarded hot-plate method is proposed using standard joint layer samples of known thermal conductivity, and the measurement results are compared with those of the laser flash method. Results showed that, based on a constant heat flux from heat source to heat sink, the temperature difference at both sides of the joint layers was proportional to the thermal resistivity of the joint layer materials. The thermal conductivity of the under-test joint layer could therefore be determined from the thermal conductivity spectrum of the known samples using a graphical method. Although the measured values by the modified guarded hot-plate method were slightly higher than those derived from the laser flash method due to the thickness effect, it was concluded that the modified guarded hot-plate method could be a practical method in measuring the thermal conductivity of thin adhesive joint layers.

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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