Thermal Conductivity and Interface Thermal Conductance in Composites of Titanium With Graphene Platelets

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
H. Zheng ◽  
K. Jaganandham
Keyword(s):  
Thermal Conductivity ◽  
Physical Vapor Deposition ◽  
Composite Films ◽  
Thermal Conductance ◽  
Single Layer ◽  
Field Analysis ◽  
Titanium Matrix ◽  
Titanium Film ◽  
Graphene Platelets ◽  
Interface Thermal Conductance

Composite films of graphene platelets (GPs) in titanium matrix were prepared on silicon (001) substrates by physical vapor deposition of titanium using magnetron sputtering and dispersion of graphene platelets. The graphene platelets were dispersed six times after each deposition of titanium film to form the composite film. Samples of titanium film and titanium film with a single layer of dispersed graphene platelets were also prepared by the same procedure. The distribution of the graphene platelets in the film was analyzed by scanning electron microscopy. Energy dispersive spectrometry was used to infer the absence of interstitial elements. The thermal conductivity of the composite and the interface thermal conductance between titanium and silicon or titanium and graphene platelets was determined by three-omega and transient thermo reflectance (TTR) techniques, respectively. The results indicate that the thermal conductivity of the composite is isotropic and improved to 40 Wm−1K−1 from 21 Wm−1 K−1 for Ti. The interface thermal conductance between titanium and silicon is found to be 200 MWm−2K−1 and that between titanium and graphene platelets in the C-direction to be 22 MWm−2K−1. Modeling using acoustic and diffuse mismatch models was carried out to infer the magnitude of interface thermal conductance. The results indicate that the higher value of interface thermal conductance between graphene platelets in the ab plane and titanium matrix is responsible for the isotropic and improved thermal conductivity of the composite. Effective mean field analysis showed that the interface thermal conductance in the ab plane is high at 440 MWm−2K−1 when GPs consist of 8 atomic layers of graphene so that it is not a limitation to improve the thermal conductivity of the composites.

scholarly journals High thermal conductive copper/diamond composites: state of the art

2020 ◽  
Vol 56 (3) ◽  
pp. 2241-2274
Author(s):  
S. Q. Jia ◽  
F. Yang
Keyword(s):  
Thermal Conductivity ◽  
Electronic Devices ◽  
Thermal Conductance ◽  
High Thermal Conductivity ◽  
Power Electronic ◽  
Practical Application ◽  
Boundary Area ◽  
Interface Characteristics ◽  
Composite Interface ◽  
Interface Thermal Conductance

Abstract Copper/diamond composites have drawn lots of attention in the last few decades, due to its potential high thermal conductivity and promising applications in high-power electronic devices. However, the bottlenecks for their practical application are high manufacturing/machining cost and uncontrollable thermal performance affected by the interface characteristics, and the interface thermal conductance mechanisms are still unclear. In this paper, we reviewed the recent research works carried out on this topic, and this primarily includes (1) evaluating the commonly acknowledged principles for acquiring high thermal conductivity of copper/diamond composites that are produced by different processing methods; (2) addressing the factors that influence the thermal conductivity of copper/diamond composites; and (3) elaborating the interface thermal conductance problem to increase the understanding of thermal transferring mechanisms in the boundary area and provide necessary guidance for future designing the composite interface structure. The links between the composite’s interface thermal conductance and thermal conductivity, which are built quantitatively via the developed models, were also reviewed in the last part.

Phonon Wave Heat Conduction in Thin Films and Superlattices

1999 ◽  
Vol 121 (4) ◽  
pp. 945-953 ◽  
Author(s):  
G. Chen
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Heat Conduction ◽  
Ray Tracing ◽  
Thermal Conductance ◽  
Single Layer ◽  
Ray Tracing Method ◽  
Conductivity Of Thin Films ◽  
Tracing Method

Heat conduction in thin films and superlattices is important for many engineering applications such as thin-film based microelectronic, photonic, thermoelectric, and thermionic devices. Past modeling efforts on the thermal conductivity of thin films were based on solving the Boltzmann transport equation that treats phonons as particles. The effects of phonon interference and tunneling on the heat conduction and the thermal conductivity of thin films and superlattices remain to be explored. In this work, the wave effects on the heat conduction in thin films and superlattices are studied based on the consideration of the acoustic wave propagation in thin film structures and neglecting the internal scattering. A transfer matrix method is used to calculate the phonon transmission and heat conduction through these structures. The effects considered in this work include the phonon interference, tunneling, and confinement. The phonon dispersion is considered by introducing frequency-dependent Lamb constants. A ray-tracing method that treats phonons as particles is also developed for comparison. Sample calculations are performed on double heterojunction structures resembling Ge/Si/Ge and n-period superlattices similar to Ge/Si/n(Si/Ge)/Ge, It is found that phonon confinements caused by the phonon spectra mismatch and by the total internal reflection create a dramatic decrease of the overall thermal conductance of thin films. The phonon interference in a single layer does not have a strong effect on its thermal conductance but for superlattice structures, the stop bands created by the interference effects can further reduce the thermal conductance. Tunneling of phonon waves occurs when the constituent layers are 1–3 monolayer thick and causes a slight recovery in the thermal conductance when compared to thicker layers. The thermal conductance obtained from the ray tracing and the wave methods approaches the same results for a single layer. For superlattices, however, the wave method leads to a finite thermal conductance even for infinitely thick superlattices while the ray tracing method gives a thermal conductance that decreases with increasing number of layers. Implications of these results on explaining the recent thermal conductivity data of superlattices are explored.

Frequency-Domain Thermoreflectance Technique for Measuring Thermal Conductivity and Interface Thermal Conductance of Thin Films

2010 ◽  
Author(s):  
Jie Zhu ◽  
Dawei Tang ◽  
Wei Wang ◽  
Jun Liu ◽  
Ronggui Yang
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Frequency Domain ◽  
Layer Structure ◽  
Modulation Frequency ◽  
Critical Role ◽  
Thermal Conductance ◽  
Dissimilar Materials ◽  
Conductivity Of Thin Films ◽  
Interface Thermal Conductance

The thermal conductivity of thin films and interface thermal conductance of dissimilar materials play a critical role in the functionality and the reliability of micro/nano-materials and devices. The transient thermoreflectance methods, including the time-domain thermoreflectance (TDTR) and the frequency-domain thermoreflectance (FDTR) techniques are excellent approaches for the challenging measurements of interface thermal conductance of dissimilar materials. A theoretical model is introduced to analyze the TDTR and FDTR signals in a tri-layer structure which consists of metal transducer, thin film, and substrate. Such a tri-layer structure represents typical sample geometry in the thermoreflectance measurements for the thermal conductivity and interface thermal conductance of thin films. The sensitivity of TDTR signals to the thermal conductivity of thin films is analyzed to show that the modulation frequency needs to be selected carefully for a high accuracy TDTR measurement. However, such a frequency selection is closely related to the unknown thermal properties and consequently hard to make before the measurement. Fortunately this limitation can be avoided in FDTR. Depending on the modulation frequency, the heat transport in such a tri-layer could be divided into three regimes based on the thickness of the film and the thermal penetration depth, the thermal conductivity of thin films and interface thermal conductance can be subsequently obtained by fitting different frequency regions of one FDTR measurement curve. FDTR measurements are then conducted along with the aforementioned analysis to obtain the thermal conductivity of SiO2 thin films and interface thermal conductance SiO2 and Si. FDTR measurement results agree well with the TDTR measurements, but promises to be a much easier implementation than TDTR measurements.

scholarly journals A Multiscale Investigation on the Thermal Transport in Polydimethylsiloxane Nanocomposites: Graphene vs Borophene

2021 ◽  
Author(s):  
Alessandro Di Pierro ◽  
Bohayra Mortazavi ◽  
Hamidreza Noori ◽  
Timon Rabczuk ◽  
Alberto Fina
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Effective Thermal Conductivity ◽  
Volume Content ◽  
Thermal Conductance ◽  
Single Layer ◽  
Interfacial Thermal Conductance ◽  
Aspect Ratios ◽  
The Matrix ◽  
Dynamics Simulations

Graphene and borophene are highly attractive two-dimensional materials with outstanding physical properties. In this study we employed a combined atomistic continuum multiscale modeling to explore the effective thermal conductivity of polymers nanocomposites made of PDMS polymer as the matrix and graphene and borophene as nanofillers. We first conduct classical molecular dynamics simulations to investigate the interfacial thermal conductance between graphene/PDMS and borophene/PDMS interfaces. Acquired results confirm that the interfacial thermal conductance between nanosheets and polymer increases from the single-layer to multilayered nanosheets and finally converges. The data provided by the atomistic simulations were then used in the finite element method simulations to evaluate the effective thermal conductivity of polymer nanocomposites at continuum level. We explore the effects of nanofillers type, their volume content, geometry aspect ratio and thickness on the nanocomposites effective thermal conductivity. As a very interesting finding, we show that borophene nanosheets, despite almost two orders of magnitude lower thermal conductivity than graphene, can yield very close enhancement in the effective thermal conductivity in comparison with graphene, particularly for low volume content and small aspect ratios and thicknesses. We conclude that for the polymer-based nanocomposites, significant improvement in the thermal conductivity can be reached by improving the bonding between the fillers and polymer or in another word enhancing the thermal conductance at the interface. By taking into account the high electrical conductivity of borophene, our results suggest borophene nanosheets as promising nanofillers to simultaneously enhance the polymers thermal and electrical conductivity.

Investigating the thermal transport in gold decorated graphene by Opto-thermal Raman technique

2021 ◽  
Author(s):  
Ranjuna M K ◽  
Jayakumar Balakrishnan
Keyword(s):  
Thermal Conductivity ◽  
Gold Nanoparticles ◽  
Thermal Management ◽  
Thermal Transport ◽  
Thermal Conductance ◽  
Single Layer ◽  
Thermal Conversion ◽  
Single Layer Graphene ◽  
Phonon Coupling ◽  
Au Nps

Abstract We report a systematic study on the thermal transport properties of gold nanoparticles (Au NPs) decorated single-layer graphene (SLG) on a SiO2/Si substrate by the Opto-thermal Raman technique. Our results, with moderate Au NPs coverage( <10%), demonstrate an enhancement in the thermal conductivity of graphene by ~ 55% from its pristine value and a decrement in the interface conductance by a factor of 1.5. A detailed analysis of our results shows the importance of the photo-thermal conversion efficiency of Au NPs, plasmon-phonon coupling and lattice modifications in the graphene developed after gold nanoparticles deposition in enhancing the thermal conductivity and reducing the interface thermal conductance of the system. Our study paves way for a better understanding of the thermal management in such hybrid systems, which are envisioned as excellent candidates for optoelectronics and photonics applications.

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