The Carbon Nanotube Based Nanocomposite with Enhanced Thermal Conductivity

2007 ◽  
Vol 121-123 ◽  
pp. 243-246 ◽  
Author(s):  
Y. Wu ◽  
C.H. Liu ◽  
H. Huang ◽  
S.S. Fan
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Thermal Contact ◽  
Current Collector ◽  
Aluminum Film ◽  
Thermal Interface Material ◽  
Heat Current ◽  
Molding Method ◽  
Aligned Carbon Nanotubes ◽  
Thermal Conducting

We present a prototype of thermal interface material (TIM) by incorporating aligned carbon nanotube arrays (CNA) into polydimethylsiloxane (PDMS). The morphology of CNA was maintained by adopting in-situ injection molding method, and the nanotube-polymer composite film was obtained by curing the PDMS at room temperature. We applied steady-state methods to measure the thermal conductivity of this kind of nanocomposite. Comparing to the pure PDMS, the thermal conductivity of the composite was greatly increased, which can be attributed to the thermal conducting passages formed by vertical aligned carbon nanotubes from one side of the film to the other. We also managed to improve the thermal conducting performance of the composite by evaporating a 1-μm-thick aluminum film on the top of a raw CNA, which serves as a heat current collector to decrease the thermal contact resistance. The experiment results suggest these kinds of composites have broad application prospect for thermal management in the future.

scholarly journals Thermal Properties of the Graphene Composites: Application of Thermal Interface Materials

2018 ◽  
Vol 7 (4.33) ◽  
pp. 530
Author(s):  
Mazlan Mohamed ◽  
Mohd Nazri Omar ◽  
Mohamad Shaiful Ashrul Ishak ◽  
Rozyanty Rahman ◽  
Zaiazmin Y.N ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Matrix Material ◽  
Thermal Interface Material ◽  
Thermal Interface Materials ◽  
Uniform Thickness ◽  
Thermal Interface ◽  
Interface Materials ◽  
Main Material

Epoxy mixed with others filler for thermal interface material (TIM) had been well conducted and developed. There are problem occurs when previous material were used as matrix material likes epoxy that has non-uniform thickness of thermal interface material produce, time taken for solidification and others. Thermal pad or thermal interface material using graphene as main material to overcome the existing problem and at the same time to increase thermal conductivity and thermal contact resistance. Three types of composite graphene were used for thermal interface material in this research. The sample that contain 10 wt. %, 20 wt. % and 30 wt. % of graphene was used with different contain of graphene oxide (GO).  The thermal conductivity of thermal interface material is both measured and it was found that the increase of amount of graphene used will increase the thermal conductivity of thermal interface material. The highest thermal conductivity is 12.8 W/ (mK) with 30 w. % graphene. The comparison between the present thermal interface material and other thermal interface material show that this present graphene-epoxy is an excellent thermal interface material in increasing thermal conductivity.  

Thermal Contact Resistance of Phase Change and Grease Type Polymeric Materials

2000 ◽  
Author(s):  
Ravi S. Prasher ◽  
Craig Simmons ◽  
Gary Solbrekken
Keyword(s):  
Thermal Conductivity ◽  
Contact Resistance ◽  
Phase Change ◽  
High Performance ◽  
Phase Change Materials ◽  
Thermal Contact ◽  
Polymeric Materials ◽  
Thermal Interface Material ◽  
Heat Spreader ◽  
Thermal Grease

Abstract Thermal interface material (TIM) between the die and the heat spreader or between the heat spreader and the heat sink in any electronic package plays a very important role in the thermal management of electronic cooling. Due to increased power and power density high-performance TIMs are sought every day. Phase change materials (PCM) seem to be very good alternative to traditionally used thermal greases because of various reasons. These phase change materials also have the advantage of being reworked easily without damaging the die. Typically these phase change materials are polymer based and are particle laden to enhance their thermal conductivity. The thermal conductivity of these materials is relatively well understood than their contact resistance. Current work focuses on explicitly measuring the contact resistance and the thermal conductivity of a particular phase change TIM and some silicon-based greases. Effect of various parameters, which can affect the contact resistance of theses TIMs and Greases, are also captured. The steady state measurements of the thermal conductivity and the contact resistance was done on an interface tester. In general the work on the contact resistance of fluid-like polymer based TIM, such as thermal grease or phase change polymer has been experimental in the past. A semi-analytical model, which captures the various parameters affecting the contact resistance of two class of materials; the phase change and the thermal grease is also developed in this paper. This model fits very well with the experimental data.

Stochastic Modeling of the Bulk Thermal Conductivity for Dense Carbon Nanotube Networks

2009 ◽  
Author(s):  
Nikhil A. Ashtekar ◽  
David A. Jack
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Contact Resistance ◽  
Thermal Transport ◽  
Power Flow ◽  
Thermal Contact ◽  
Separation Distance ◽  
Bulk Conductivity ◽  
Carbon Nanotube Networks ◽  
Bulk Thermal Conductivity

A computational, physics-based, bulk thermal conductivity model of a neat carbon nanotube network at room temperature is developed using classical finite element techniques. The model is based on experimentally available stochastic distributions of length, diameter, chirality, and orientation, and uses theoretical results for thermal contact resistance from the literature and molecular dynamics simulations for the stochastic nature of tube separation distance. Understanding the thermal transport properties of carbon nanotube networks at various operating temperatures is crucial for the industrial acceptance of these materials in aerospace and electrical applications. Mechanisms of thermal transport are discussed including; thermal conductivity along the tube and inter-contact resistance between the tubes, where the later is considered the dominating factor. The effect of variations of several of the aforementioned stochastic factors influencing the bulk conductivity is investigated, and results demonstrate that changes in the nanotube length play a significant role in improving the bulk conductivity of the network. In addition, a brief study into localized power flow is presented and lends insight into a possible cause of premature network failure.

Anisotropic Heat Conduction Effects in Proton-Exchange Membrane Fuel Cells

2006 ◽  
Vol 129 (9) ◽  
pp. 1109-1118 ◽  
Author(s):  
Chaitanya J. Bapat ◽  
Stefan T. Thynell
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Thermal Contact ◽  
Current Collector ◽  
Gas Diffusion ◽  
Thermal Contact Conductance ◽  
Contact Conductance ◽  
Gas Diffusion Layers ◽  
Diffusion Layers ◽  
Anisotropic Thermal Conductivity

The focus of this work is to study the effects of anisotropic thermal conductivity and thermal contact conductance on the overall temperature distribution inside a fuel cell. The gas-diffusion layers and membrane are expected to possess an anisotropic thermal conductivity, whereas a contact resistance is present between the current collectors and gas-diffusion layers. A two-dimensional single phase model is used to capture transport phenomena inside the cell. From the use of this model, it is predicted that the maximum temperatures inside the cell can be appreciably higher than the operating temperature of the cell. A high value of the in-plane thermal conductivity for the gas-diffusion layers was seen to be essential for achieving smaller temperature gradients. However, the maximum improvement in the heat transfer characteristics of the fuel cell brought about by increasing the in-plane thermal conductivity is limited by the presence of a finite thermal contact conductance at the diffusion layer/current collector interface. This was determined to be even more important for thin gas-diffusion layers. Anisotropic thermal conductivity of the membrane, however, did not have a significant impact on the temperature distribution. The thermal contact conductance at the diffusion layer/current collector interface strongly affected the temperature distribution inside the cell.

Improvement of Thermal Conductivity of Silicone by Carbon Nanotube Array (CNTA)

2014 ◽  
Vol 1061-1062 ◽  
pp. 96-99 ◽  
Author(s):  
Liang Ke Wu ◽  
Ji Ying ◽  
Li Ting Chen
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Thermal Interface Material ◽  
Flash Method ◽  
Nanotube Array ◽  
Thermal Interface ◽  
Carbon Nanotube Array ◽  
Operating Temperatures

In order to improve the thermal conductivity of silicone, we prepared silicone/carbon nanotube array (CNTA) composite by immersing the CNTA into silicone solution and cured at 110 °C. The thermal conductivity of silicone and silicone/CNTA composite was measured by laser flash method at 30 °C, 60 °C, 90 °C, 120 °C, which are usually the operating temperatures. It was found that the thermal conductivity of silicone/CNTA composite increased with the temperature until achieved the plateau near 90 °C. The maximum thermal conductivity of silicone/CNTA composite is 0.674 W/mK, which is 220% higher than that of neat silicone. The excellent thermal conductivity makes the composite a promising thermal interface material.

Sodium Silicate Based Thermal Interface Material for High Thermal Contact Conductance

1999 ◽  
Vol 122 (2) ◽  
pp. 128-131 ◽  
Author(s):  
Yunsheng Xu ◽  
Xiangcheng Luo ◽  
D. D. L. Chung
Keyword(s):  
Thermal Conductivity ◽  
Boron Nitride ◽  
Sodium Silicate ◽  
Hexagonal Boron Nitride ◽  
Thermal Contact ◽  
Mineral Oil ◽  
Thermal Interface Material ◽  
Thermal Contact Conductance ◽  
Thermal Interface ◽  
Contact Conductance

Sodium silicate based thermal interface pastes give higher thermal contact conductance across conductor surfaces than polymer based pastes and oils, due to their higher fluidity and the consequent greater conformability. Addition of hexagonal boron nitride particles up to 16.0 vol. percent further increases the conductance of sodium silicate, due to the higher thermal conductivity of BN. However, addition beyond 16.0 vol. percent BN causes the conductance to decrease, due to the decrease in fluidity. At 16.0 vol. percent BN, the conductance is up to 63 percent higher than those given by silicone based pastes and is almost as high as that given by solder. Water is almost as effective as sodium silicate without filler, but the thermal contact conductance decreases with time due to the evaporation of water. Mineral oil and silicone without filler are much less effective than water or sodium silicate without filler. [S1043-7398(00)00402-3]

Comparison between CNT Thermal Interface Materials with Graphene Thermal Interface Material in Term of Thermal Conductivity

2020 ◽  
Vol 1010 ◽  
pp. 160-165
Author(s):  
Mazlan Mohamed ◽  
Mohd Nazri Omar ◽  
Mohamad Shaiful Ashrul Ishak ◽  
Rozyanty Rahman ◽  
Nor Zaiazmin Yahaya ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Thermal Interface Material ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Mixed Material ◽  
Interface Materials ◽  
Main Material

Thermal interface material (TIM) had been well conducted and developed by using several material as based material. A lot of combination and mixed material were used to increase thermal properties of TIM. Combination between materials for examples carbon nanotubes (CNT) and epoxy had had been used before but the significant of the studied are not exactly like predicted. In this studied, thermal interface material using graphene and CNT as main material were used to increase thermal conductivity and thermal contact resistance. These two types of TIM had been compare to each other in order to find wich material were able to increase the thermal conductivity better. The sample that contain 20 wt. %, 40 wt. % and 60 wt. % of graphene and CNT were used in this studied. The thermal conductivity of thermal interface material is both measured and it was found that TIM made of graphene had better thermal conductivity than CNT. The highest thermal conductivity is 23.2 W/ (mK) with 60 w. % graphene meanwhile at 60 w. % of CNT only produce 12.2 W/ (mK thermal conductivity).

Characterization of Carbon Nanotube Array Based Thermal Interface Material After Bonding Process

2010 ◽  
Author(s):  
Rong-Shiuan Chu ◽  
Yang Zhao ◽  
Arun Majumdar
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Contact Resistance ◽  
Target Surface ◽  
Thermal Interface Material ◽  
Bonding Layer ◽  
Nanotube Array ◽  
Thermal Interface ◽  
Carbon Nanotube Array ◽  
Overall Resistance

Vertically Aligned Carbon Nanotube (CNT) Arrays are promising to use as advanced thermal interface material. While possessing high thermal conductivity for an individual tube, carbon nanotube array based thermal interface materials (TIMs) fell short of expectations due to poor CNTs-target surface contacts. Investigations suggested that the overall resistance can be potentially reduced to less than 1 m2-K/MW by increasing the number of tubes to target surface contacts. This paper use chromium/gold/indium assisted thermal pressure-bonding to enhance contacts. A CNT array with 12.7% areal density was bonded to an experimental glass surface with 2-μm indium bonding layer and 10 nm-chromium/150 nm-gold adhesion layers under pressure of 196 KPa and temperature of 350 °C. Phase sensitive photothermal reflectance method was used for thermal measurement. The overall resistance, including CNTs-glass contact resistance and effective CNT array thermal resistance, is 1.1 m2-K/MW ± 27%. Although the contact resistance was reduced to 0.39 m2-K/MW ± 15%, the effective thermal conductivity of the post-bonded 80 μm long CNTs was 114 W/m-K ± 22%, which was lower than the expected lower bound of the thermal conductivity of 12.7% filled CNT array. It was suggested that the deformation of CNT array after mechanical bonding reduced its performance.

Nanofluids Containing Hybrid Sphere/Carbon Nanotube Particles

2007 ◽  
Author(s):  
Zenghu Han ◽  
Bao Yang ◽  
S. H. Kim ◽  
M. R. Zachariah
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Room Temperature ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Hybrid Nanoparticles ◽  
Particle Volume ◽  
Alpha Olefin ◽  
Wire Method ◽  
New Type

Previous studies on nanofluids have focused on spherical or long-fiber particles. In this work, a new type of complex nanoparticles—hybrid sphere/carbon nanotube (CNT) particle, consisting of numerous CNTs attached to an alumina/iron oxide sphere—is proposed for applications in nanofluids. In such hybrid nanoparticles, heat is expected to transport rapidly from one CNT to another through the center sphere and thus leading to less thermal-contact-resistance between CNTs when compared to simple CNTs dispersed in fluids. CNTs have an extremely high thermal conductivity, but thermal resistance between the CNTs and the fluid has limited their performance in the nanofluids. The proposed hybrid sphere/CNT particles are synthesized by a spray pyrolysis followed by catalytic growth of CNTs. The spheres are about 70 nm in diameter in average, and the attached CNTs have a length up to 2μm. These hybrid nanoparticles are dispersed to poly-alpha-olefin with sonication and a small amount of surfactants to form stable nanofluids. The thermal conductivity of the fluids has been measured by a 3ω-wire method over a temperature range 10–90°C. The results indicate that the effective thermal conductivity of the fluids is increased by about 21% at room temperature for particle volume fractions of 0.2%.

Transient Thermo-Reflectance Method for Characterization of Thermal Interface Material Based on Carbon Nanotube Array

2009 ◽  
Author(s):  
Yang Zhao ◽  
Rong-Shiuan Chu ◽  
Arun Majumdar
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Thermal Resistance ◽  
Thermal Interface Material ◽  
Measuring System ◽  
Bonding Layer ◽  
Thermal Interface ◽  
Interface Resistance ◽  
Interface Thermal Resistance ◽  
Cnt Arrays

Vertically aligned carbon nanotube (CNT) arrays have been explored as advanced thermal interface materials because of their compliance and high cross-plane thermal conductivity. Our previous work showed that a CNT array directly bridging two surfaces by dry contact had a surface-surface interface resistance of order of 10 m2-K/MW. With an indium bonding layer, the interface thermal resistance was reduced by a factor of ten. Therefore, a more sensitive measuring system is needed to accurately determine the thermal resistance. In this paper, we achieved a higher sensitivity measurement by applying the phase sensitive transient thermo-reflectance technique to a front side heating and detecting system. A detailed analysis is presented. We used this technique to characterize a 71-μm long CNT array with packing density of 9.4 ± 1.4%. The CNT array was sequentially wetted with chromium/gold films and was bonded to a glass surface with an indium bonding layer. We found that the CNT array-surface interface resistance is 0.35 ± 0.11 m2-K/MW and the cross-plane thermal conductivity of CNT array is 94 ± 40 W/m-K.

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