scholarly journals Interfacial Structure of Carbide-Coated Graphite/Al Composites and Its Effect on Thermal Conductivity and Strength

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1721
Author(s):  
Hao Jia ◽  
Jianzhong Fan ◽  
Yanqiang Liu ◽  
Yuehong Zhao ◽  
Junhui Nie ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Hot Isostatic Pressing ◽  
Thermal Conductance ◽  
Interfacial Structure ◽  
Carbide Coating ◽  
Laminate Composites ◽  
Interfacial Thermal Conductance ◽  
Carbide Coatings

Graphite/Al composites had attracted significant attention for thermal management applications due to their excellent thermal properties. However, the improvement of thermal properties was restricted by the insufficient wettability between graphite and Al. In this study, silicon carbide and titanium carbide coatings have been uniformly coated on the graphite by the reactive sputtering method, and Graphite/Al laminate composites were fabricated by a hot isostatic pressing process to investigate the influence on thermal conductivity and mechanical properties. The results show that carbide coating can effectively improve the interfacial thermal conductance of SiC@Graphite/Al and TiC@Graphite/Al composites by 9.8 times and 3.4 times, respectively. After surface modification, the in-plane thermal conductivity (TC) of the composites with different volume fractions are all exceeding the 90% of the predictions. In comparison, SiC is more conducive to improving the thermal conductivity of composite materials, since the thermal conductivity of the 28.7 vol.% SiC@Graphite/Al reached the highest value of 499 W/m·K, while TiC is favorable for improving the mechanical properties. The finding is beneficial to the understanding of carbide coating engineering in the Graphite/Al composites.

Evaluating Thermal Cycling Fatigue Resistance for LED Chip-on-Board Applications

2012 ◽  
Vol 2012 (DPC) ◽  
pp. 000706-000737
Author(s):  
Ravi M. Bhatkal ◽  
Ranjit Pandher ◽  
Anna Lifton ◽  
Paul Koep ◽  
Hafez Raeisi Fard
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Cycle ◽  
Metal Core ◽  
Creep Fatigue ◽  
Cte Mismatch ◽  
Thermal Cycling Fatigue ◽  
Transient Thermal ◽  
The Impact

LED chip-on-board applications typically involve assembling an LED die stack directly on to a high thermal conductivity substrate such as a Metal Core PCB. If solder is used for die-substrate attach for such chip-on-board applications, one needs to consider the CTE mismatch between the die stack and the MCPCB and its impact on thermal cycle-induced creep fatigue of the solder material. This paper presents a methodology to compare relative performance of different solder materials with varying thermo-mechanical properties, and compare the impact of CTE mismatch and temperature swings on transient thermal properties and relative reliability of the solder attach materials. Implications for LED chip-on-board applications are discussed.

The Effect of Surface Active Substances on the Mechanical Properties of a Copper-Matrix Nanocomposite

2019 ◽  
Vol 945 ◽  
pp. 493-497
Author(s):  
Y. Shchetinin ◽  
Y. Kopylov ◽  
A. Zhirkov
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Composite Material ◽  
Carbon Nanostructures ◽  
Hot Isostatic Pressing ◽  
Copper Matrix ◽  
Planetary Mill ◽  
Preliminary Treatment ◽  
Nanostructured Composite ◽  
The Matrix

The presented work reviews the research in the field of production of nanostructured composite materials based on copper, reinforced with carbon nanostructures. Particular attention is paid to the use of composites with high thermal conductivity as structural materials. The method of manufacturing a composite material based on copper is described in detail: modes of preliminary annealing, pre-pressing, hot isostatic pressing. The characteristics of the matrix and alloying components are given, and also preliminary treatment of copper powder and carbon nanotubes is described. Different mechanisms of component mixing are considered, the process of mechanical alloying in a planetary mill is described in detail, the results of measuring the thermal conductivity of samples are given. The mechanical characteristics of the samples are considered in detail: ultimate strength, yield strength, elongation. The degree of influence of surfactants on the uniformity of the distribution of alloying components and the mechanical properties of the composite material is determined.

Thermal Properties of Nanotubes and Nanowires With Acoustically Stiffened Surfaces

2011 ◽  
Author(s):  
Michael F. P. Bifano ◽  
Vikas Prakash
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Specific Heat ◽  
Phonon Dispersion ◽  
Thermal Conductance ◽  
Frequency Equation ◽  
Outer Diameter ◽  
Phonon Confinement ◽  
Maximum Increase ◽  
Acoustic Tuning

A core-shell elasticity model is employed to investigate the effect of a nanowire and nanotube’s increased surface moduli on specific heat, ballistic thermal conductance, and thermal conductivity as a function of temperature. Phonon confinement is analyzed using approximated phonon dispersion relations that result from solutions to the frequency equation of a vibrating rod and tube. The results indicate a maximum 10% decrease in lattice thermal conductivity and ballistic thermal conductance near 160 K for a 10 nm outer diameter nanotube with an inner diameter of 5 nm when the average Young’s Modulus of both the inner and outer free surfaces is increased by a factor of 1.53. In the presence of the acoustically stiffened surfaces, the specific heat of the nanotube is found to decrease by up to 20% at 160 K. Near room temperature, changes in thermal properties are less severe. In contrast, a 10 nm outer diameter nanowire composed of similar material exhibits up to a 12% maximum increase in thermal conductivity at 600 K, a 25% increase in ballistic thermal conductance at 400 K, and a 48% increase in specific heat at 470 K when its outer free surface is acoustically stiffened to the same degree. Our simplified model may be extended to investigate the acoustic tuning of nanowires and nanotubes by inducing surface stiffening or softening via appropriate surface chemical functionalization and coatings.

Effect of extrusion treatment on mechanical, thermal conductivity and corrosion resistance of magnesium alloys

2019 ◽  
Vol 9 (5) ◽  
pp. 405-412
Author(s):  
Bo Zhang ◽  
Huichao Jia ◽  
Quanyong Lian ◽  
Lianyu Jiang ◽  
Guangxin Wu
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Corrosion Resistance ◽  
Thermal Properties ◽  
Magnesium Alloys ◽  
Driving Force ◽  
Mechanical Performance ◽  
Cast Alloy ◽  
Extrusion Temperature ◽  
Zr Alloys

The effect of extrusion treatment on the mechanical, thermal and corrosion resistance of Mg–La–Zn–Zr alloys were presented. It is suggested that the amount of recrystallized grains played a major role in both mechanical properties and thermal properties. It should be noted the as-cast alloy shows the best thermal conductivity reached the value about 137.507 W/(m · K), however, the mechanical performance of magnesium alloys does not reach the expected results. The thermal properties of extruded alloys have slightly decreased and then increased with the increase of extrusion temperature. Then the tensile properties of Mg–La–Zn–Zr were significantly improved after extrusion treatment. Furthermore, with the increase of extrusion temperature, the elongation-to-fracture increased substantially. After extrusion treatment, the corrosion driving force of the alloy decreases, which reduces the corrosion tendency of the magnesium alloy. The alloy presented in this paper is expected to be applied in industry.

scholarly journals Interfacial Thermal Conductance across Graphene/MoS2 van der Waals Heterostructures

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5851
Author(s):  
Shuang Wu ◽  
Jifen Wang ◽  
Huaqing Xie ◽  
Zhixiong Guo
Keyword(s):  
Thermal Conductivity ◽  
First Principles ◽  
Van Der Waals ◽  
Thermal Conductance ◽  
Md Simulations ◽  
Monolayer Graphene ◽  
Density Of State ◽  
Interfacial Thermal Conductance ◽  
Van Der Waals Heterostructure ◽  
Phonon Spectra

The thermal conductivity and interface thermal conductance of graphene stacked MoS2 (graphene/MoS2) van der Waals heterostructure were studied by the first principles and molecular dynamics (MD) simulations. Firstly, two different heterostructures were established and optimized by VASP. Subsequently, we obtained the thermal conductivity (K) and interfacial thermal conductance (G) via MD simulations. The predicted Κ of monolayer graphene and monolayer MoS2 reached 1458.7 W/m K and 55.27 W/m K, respectively. The thermal conductance across the graphene/MoS2 interface was calculated to be 8.95 MW/m2 K at 300 K. The G increases with temperature and the interface coupling strength. Finally, the phonon spectra and phonon density of state were obtained to analyze the changing mechanism of thermal conductivity and thermal conductance.

Preparation and Characterization of GNP/Nylon Composites

2014 ◽  
Vol 556-562 ◽  
pp. 339-342 ◽  
Author(s):  
Bao Feng Xu ◽  
Zhi Dan Lin ◽  
Jiang Ming Chen ◽  
Jun Lin
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Graphene Nanoplatelets ◽  
Melt Blending ◽  
Blending Method

Graphene nanoplatelets (GNP) and nylon (PA) have been often used as thermal filler and matrix and respectively to produce composites. In this work, PA6/PA66/GNP thermal composites were prepared via a melt blending method. Mechanical properties, morphology, and thermal properties of PA6/PA66/GNP composites were investigated. Because the GNP is very expensive, we investigated to use Al2O3 and graphite and examined the characteristics of the prepared composites. Thermal conductivity values of PA6/PA66/GNP composites remarkably increased with increase of GNP contents mainly via layered dispersion in nylon matrix. The thermal conductivity of composite containing 50 wt % of GNP was measured as 5.03 W·m–1·K–1 at 30 °C, indicating an increase of more than 15 times compared with that of the neat PA6. When the Al2O3 was replaced for GNP, the thermal conductivity of composites decreased, but the mechanical properties improved. When graphite was used to replace for GNP, thermal conductivity basically remained unchanged but mechanical properties decreased.

Thermal Properties and Fire Performance of Woven Glass Fibre Reinforced Nylon 6 Nano-Composites with Carbon Nanotubes

2008 ◽  
Vol 32 ◽  
pp. 9-12
Author(s):  
Shirley Zhiqi Shen ◽  
Stuart Bateman ◽  
Qiang Yuan ◽  
Mel Dell'Olio ◽  
Januar Gotama ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Thermal Properties ◽  
Ignition Time ◽  
Nylon 6 ◽  
Nano Composites ◽  
Fire Performance ◽  
Thermal Stabilities ◽  
Glass Fibre Reinforced

This paper presents the effects of incorporating carbon nanotubes (CNT) into nylon 6 on thermal properties and fire performance of woven glass reinforced CNT/nylon 6 nanocomposite laminates. Incorporation of CNT in nylon 6 improved the thermal stabilities, thermal conductivity and fire performance of laminates without compromising their mechanical properties. The thermal conductivity of laminates with 2 wt% CNT increased up to 42% compared to that without CNT. The ignition time and peak HRR time was delayed approx. 31% and 118%, respectively, in laminates with 4 wt% CNT in nylon 6 over that without CNT.

Effects of Thickness on Thermal and Mechanical Properties of Air-Plasma Sprayed Thermal Barrier Coatings

2010 ◽  
Vol 658 ◽  
pp. 372-375 ◽  
Author(s):  
Sang Yeop Lee ◽  
Jae Young Kwon ◽  
Tae Woong Kang ◽  
Yeon Gil Jung ◽  
Ung Yu Paik
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Exposure Time ◽  
Gas Turbines ◽  
Microstructural Analysis ◽  
Thermal Exposure ◽  
Thermal Barrier ◽  
Air Plasma

Thermal barrier coating systems (TBCs) prepared by an air-plasma spray (APS) have been used to protect metallic components of gas turbines because of its economic advantage. To enhance the energy efficiency of gas turbine systems, the operating temperature is increased to over 1300 °C, which requires a new material with low thermal conductivity and an increase of TBC thickness. In this study we have focused the microstructure related to the thickness of TBC and their thermal properties, with specific attention to defect species as well as to its morphology with the thermal exposure time. Resintering of TBC happens during thermal exposure in a high temperature, resulting in the less strain tolerance and the higher thermal conductivity. In order to investigate the thermal properties of TBC related to the microstructural evolution, TBCs with different thicknesses of 200 µm, 400 µm, 600 µm, and 2000 µm were deposited on a flat graphite by the APS. The thermal exposure tests were conducted in different dwell time till 800h at 1100 °C. The thermal diffusivity is significantly increased after thermal exposures, depending on the thermal exposure time. Microstructural analysis clearly shows that the variation of thermal diffusivity is ascribed to the coalescence of small cracks and the resintering effect. The hardness values of TBCs are also increased as well. The relationship between mechanical properties and TBC thickness is discussed, including the effect of thickness on thermal properties.

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