scholarly journals Thermal conductivity reduction by nanostructuration in electrodeposited CuNi alloys

2021 ◽  
Author(s):  
Cristina V. Manzano ◽  
Olga Caballero-Calero ◽  
Maxime Tranchant ◽  
Enrico Bertero ◽  
Pablo Cervino-Solana ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Crystallite Size ◽  
A Value ◽  
Pulsed Electrodeposition

The thermal conductivity of CuNi alloys grown by pulsed electrodeposition is reduced by the nanostructuration to a value of 9.0 ± 0.9 W m−1 K−1 due to the incorporation of saccharine in the electrolyte which allowed reduction of the crystallite size.

Effects of Nb doping on thermoelectric properties of Zn4Sb3 at high temperatures

2009 ◽  
Vol 24 (2) ◽  
pp. 430-435 ◽  
Author(s):  
D. Li ◽  
H.H. Hng ◽  
J. Ma ◽  
X.Y. Qin
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
High Temperatures ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Thermoelectric Performance ◽  
Temperature Range ◽  
A Value ◽  
Nb Doping ◽  
Thermal Conductivities

The thermoelectric properties of Nb-doped Zn4Sb3 compounds, (Zn1–xNbx)4Sb3 (x = 0, 0.005, and 0.01), were investigated at temperatures ranging from 300 to 685 K. The results showed that by substituting Zn with Nb, the thermal conductivities of all the Nb-doped compounds were lower than that of the pristine β-Zn4Sb3. Among the compounds studied, the lightly substituted (Zn0.995Nb0.005)4Sb3 compound exhibited the best thermoelectric performance due to the improvement in both its electrical resistivity and thermal conductivity. Its figure of merit, ZT, was greater than the undoped Zn4Sb3 compound for the temperature range investigated. In particular, the ZT of (Zn0.995Nb0.005)4Sb3 reached a value of 1.1 at 680 K, which was 69% greater than that of the undoped Zn4Sb3 obtained in this study.

THERMAL CONDUCTIVITY AND THERMAL AGING PERFORMANCE OF Sn WITH 0.7 wt.% Cu and VARIOUS GRAPHENE ADDITIONS

2019 ◽  
Vol 27 (06) ◽  
pp. 1950161
Author(s):  
CAIXIA SUN ◽  
FENGYUN ZHANG ◽  
HONGXIA ZHANG ◽  
NIANLONG ZHANG ◽  
SHOUYING LI ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Composite Material ◽  
Composite Materials ◽  
Thermal Aging ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
A Value ◽  
Aging Test ◽  
Accelerated Thermal Aging ◽  
Aging Performance

The effect of graphene content (0.08, 0.16 and 0.33[Formula: see text]wt.%) on the thermal conductivity and thermal aging performance of an Sn based composite material with 0.7[Formula: see text]wt.% Cu and various graphene additions was investigated via X-ray diffraction (XRD), scanning electron microscope (SEM) and accelerated thermal aging test. The XRD results showed that the graphene diffraction intensity was weak (approximately 10∘) due to little content and distribution of the graphene on the surface of the composite materials. After thermal aging testing the diffraction intensity on some crystal planes of the composite materials was enhanced, proving that preferential growth occurs on the crystal plane. SEM results showed that before aging testing no whiskers were generated on the surface of the composite materials. After the accelerated thermal aging at 100∘C for 24[Formula: see text]h, whisker growth became apparent in the composite materials. All the whiskers were located in the grains rather than on the grain boundaries of the composite materials. The highest thermal conductivity was obtained at 0.16[Formula: see text]wt.% graphene addition (indicated as 0.16[Formula: see text]wt.% graphene–0.7[Formula: see text]wt.% Cu/Sn). After the accelerated thermal aging at 100∘C for 24[Formula: see text]h, the bamboo-shaped whiskers with a low aspect ratio grew in large quantities on the surface of the 0.16[Formula: see text]wt.% graphene–0.7[Formula: see text]wt.% Cu/Sn composite material, while when the aging was at 100∘C for 366[Formula: see text]h the thermal conductivity decreased from 67[Formula: see text]W[Formula: see text][Formula: see text][Formula: see text][Formula: see text] to 52[Formula: see text]W[Formula: see text][Formula: see text][Formula: see text][Formula: see text]. When the graphene addition was 0.33[Formula: see text]wt.% (indicated as 0.33[Formula: see text]wt.% graphene–0.7[Formula: see text]wt.% Cu/Sn) the thermal conductivity maintains a value above 59[Formula: see text]W[Formula: see text][Formula: see text][Formula: see text][Formula: see text] after the accelerated thermal aging.

scholarly journals Phonon hydrodynamics and ultrahigh–room-temperature thermal conductivity in thin graphite

Science ◽  
2020 ◽  
Vol 367 (6475) ◽  
pp. 309-312 ◽  
Author(s):  
Yo Machida ◽  
Nayuta Matsumoto ◽  
Takayuki Isono ◽  
Kamran Behnia
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Wide Temperature Range ◽  
Room Temperature ◽  
Phonon Dispersion ◽  
High Conductivity ◽  
Temperature Range ◽  
A Value ◽  
Out Of Plane ◽  
Intimate Link

Allotropes of carbon, such as diamond and graphene, are among the best conductors of heat. We monitored the evolution of thermal conductivity in thin graphite as a function of temperature and thickness and found an intimate link between high conductivity, thickness, and phonon hydrodynamics. The room-temperature in-plane thermal conductivity of 8.5-micrometer-thick graphite was 4300 watts per meter-kelvin—a value well above that for diamond and slightly larger than in isotopically purified graphene. Warming enhances thermal diffusivity across a wide temperature range, supporting partially hydrodynamic phonon flow. The enhancement of thermal conductivity that we observed with decreasing thickness points to a correlation between the out-of-plane momentum of phonons and the fraction of momentum-relaxing collisions. We argue that this is due to the extreme phonon dispersion anisotropy in graphite.

Effect of Nanocellulose on Acoustical and Thermal Insulation Properties of Silicone Rubber Composite

2019 ◽  
Vol 964 ◽  
pp. 156-160 ◽  
Author(s):  
Mohammad Farid ◽  
Agung Purniawan ◽  
Diah Susanti ◽  
Amaliya Rasyida ◽  
Henry Yulianto ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Absorption Coefficient ◽  
Silicone Rubber ◽  
Sound Absorption ◽  
Wide Band ◽  
Sound Absorption Coefficient ◽  
Empty Fruit Bunch ◽  
A Value ◽  
Rubber Composite ◽  
The Matrix

Nanocellulose composites are very potential to be applied as automotive component materials.The purpose of this research is to analyze the influence of nanocellulose fraction of the silicon rubber composite material to morphology, sound absorption coefficient, density, thermal stability, and thermal conductivity. The nanocellulose of the composites were isolated from oil palm empty fruit bunch, while the matrix was silicone rubber. Tests conducted in this research included sound absorption coefficient, SEM, TGA, density, and thermal conductivity. Sound absorption coefficient had a value between 0,33 to 0.42 for a frequency of 500 Hz to 4000 Hz. This sound absorption coefficient had a wide band sound absorption tendency and was developed for sound absorption material of mufflers.

Wärmeleitfähigkeit, elektrische Leitfähigkeit, Hall-Effekt, Thermospannung und spezifische Wärme von Ag2Se

1962 ◽  
Vol 17 (10) ◽  
pp. 886-889 ◽  
Author(s):  
Y. Baer ◽  
G. Busch ◽  
C. Fröhlich ◽  
E. Steigmeier
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Low Temperature ◽  
Specific Heat ◽  
Thermoelectric Power ◽  
Hall Coefficient ◽  
A Value ◽  
Price Formula ◽  
Elektrische Leitfähigkeit ◽  
Increasing Temperature

The thermal conductivity, electrical conductivity. Hall coefficient und thermoelectric power of Ag2Se have been measured between 80 and 600°K. In the low temperature semiconductor phase the thermal conductivity increases with increasing temperature due to the high amount of carrier contribution. The latter has been calculated using the Price formula. Agreement with experiment is satisfactory. The specific heat has been measured between 30 and 200°C. For the latent heat a value of (5.7 ± 0.5) cal/gr was determined in agreement with measurements of Bellati and Lussana 4. In addition to the transition at 133 °C an unknown new transition has been found at about 90 °C.

Effect of γ-PVDF on enhanced thermal conductivity and dielectric property of Fe-rGO incorporated PVDF based flexible nanocomposite film for efficient thermal management and energy storage applications

RSC Advances ◽  
2016 ◽  
Vol 6 (44) ◽  
pp. 37773-37783 ◽  
Author(s):  
Sumanta Kumar Karan ◽  
Amit Kumar Das ◽  
Ranadip Bera ◽  
Sarbaranjan Paria ◽  
Anirban Maitra ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Dielectric Property ◽  
Energy Density ◽  
Crystallite Size ◽  
Thermal Management ◽  
Nanocomposite Film ◽  
Energy Storage Applications ◽  
Enhanced Thermal Conductivity

Dependence of thermal conductivity and energy density on the amount of crystalline γ-phase and γ-crystallite size of PVDF in Fe-rGO/PVDF nanocomposites has been explored.

Heat Transfer in Encased Graphene

2009 ◽  
Author(s):  
Zhen Chen ◽  
Wanyoung Jang ◽  
Wenzhong Bao ◽  
Chun Ning Lau ◽  
Chris Dames
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Room Temperature ◽  
Heat Dissipation ◽  
Thermal Contact ◽  
Graphene Sheets ◽  
A Value ◽  
Order Of Magnitude ◽  
Device Applications ◽  
Freely Suspended

Experimentally understanding the heat transfer in graphene (sheets of graphite a few atoms thick) is important for fundamental physics as well as device applications. In particular, measurements of the heat flow through graphene encased by oxide layers are essential for future graphene-based nanoelectronics, interconnects, and thermal management structures. Here we use a “heat spreader method” to study the heat dissipation performance of encased graphene. Measurements show enhanced heat spreading by a graphene layer as compared to control samples without graphene. At room temperature, the in-plane thermal conductivity of encased graphene sheets of thickness 2 nm and 5 nm is measured to be ∼150 W/m-K, more than one order of magnitude smaller than a published report for a freely-suspended graphene sheet [A. A. Balandin et al., Nano Lett. 8, 902], as well as bulk graphite. We also used a differential 3ω method to measure the thermal contact resistance between graphene and SiO2, finding a value around 10−8 m2-K/W at room temperature. Possible reasons for the unexpectedly low thermal conductivity are also discussed.

Influence of crystallite size on the thermal conductivity in BaTiO3 nanoceramics

2007 ◽  
Vol 90 (11) ◽  
pp. 114104 ◽  
Author(s):  
A. Jeżowski ◽  
J. Mucha ◽  
R. Pazik ◽  
W. Strek
Keyword(s):  
Thermal Conductivity ◽  
Crystallite Size

Phase Change Problems With Temperature-Dependent Thermal Conductivity

1974 ◽  
Vol 96 (2) ◽  
pp. 214-217 ◽  
Author(s):  
S. H. Cho ◽  
J. E. Sunderland
Keyword(s):  
Thermal Conductivity ◽  
Exact Solution ◽  
Phase Change ◽  
The Body ◽  
Temperature Dependent ◽  
Fusion Temperature ◽  
Infinite Body ◽  
A Value ◽  
Change Position ◽  
Temperature Dependent Thermal Conductivity

An exact solution is presented for the temperature distribution and phase change position of a semi-infinite body which is initially at a constant temperature different from the fusion temperature. The temperature of the free surface is instantaneously changed and held constant at a value that will cause either melting or solidification of the body. The thermal conductivity is assumed to vary linearly with temperature. The convection in the liquid phase due to density change is also considered.

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