Fabrication and effective thermal conductivity of multi-walled carbon nanotubes reinforced Cu matrix composites for heat sink applications

Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Composites Science and Technology (Impact Factor: 3.57). 02/2010; 70(2):298-304. DOI: 10.1016/j.compscitech.2009.10.021


A novel particles-compositing method was used for the first time to disperse different contents of multi-walled carbon nanotubes (CNTs) in micron sized copper powders, which were subsequently consolidated into CNT/Cu composites by spark plasma sintering (SPS). Microstructural observations showed that the homogeneous distribution of CNTs and dense composites could be obtained for 0–10 vol.% CNT contents. The CNT clusters were appeared in the powder mixture with 15 vol.% CNTs, which resulted in an insufficient densification of the composites. The effective thermal conductivity of the composites was analyzed both theoretically and experimentally. The addition of CNTs showed no enhancement in overall thermal conductivity of the composites due to the interface thermal resistance associated with the low phase contrast of CNT to copper and the random tube orientation. Besides, the composite containing 15 vol.% CNTs led to a rather low thermal conductivity due possiblely to the combined effect of unfavorable factors induced by the presence of CNT clusters, i.e. large porosity, lower effective conductivity of CNT clusters themselves and reduction of SPS cleaning effect. The CNT/Cu composites may be a promising thermal management material for heat sink applications.

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    • "CNTs find their applications in the form of additives in structural materials such as golf stub, boat, aircraft and bicycles. By mixing it in the solid [5] [6] [7] [8] or fluid [9] [10] [11] [12], the mixture can effectively enhance the thermal performance and mechanical properties of the base materials. So, the CNTs employed in the field are examined with great potential for the heat transfer applications. "
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    AEJ - Alexandria Engineering Journal 06/2015; 297. DOI:10.1016/j.aej.2015.05.009
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    • "The orientation of the measured thermal transport could be different to the orientation of CNT in the Cu matrix after consolidation. The random distribution of CNT orientation could disturb the unidirectional heat transfer which could result in the reduction of the effective heat conduction of CNTs [31]. Cho et al. [30] reported the thermal conductivity of 359.2 W/mK for Cu-1 vol%CNT sintered at 550 °C with 50 MPa. "
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    ABSTRACT: Submicron copper reinforced with carbon nanotubes–ruthenium composites as suitable material for thermal management applications has been fabricated by Spark plasma sintering (SPS). The slurry of CNT–Ru was uniformly dispersed into copper matrix by mechanical stirring process using ethanol as a mixing medium. The composites powders were initially annealed for 30 min at 550 °C with heating rate of 5 °C/min under argon. The annealed powders were then consolidated at sintering temperature of 600 °C and 650 °C with a constant pressure of 50 MPa and the holding time of 5 min. The relative density of 98.15% was obtained for Cu-2 vol%CNT while that of Cu-2 vol%CNT-0.5 vol%Ru was of 97.08%. The Vickers hardness values of Cu-2 vol%CNT-0.5 vol%Ru sintered at 650 °C were found to be 130.4 HV. The coefficient of thermal expansion of 2.3 × 10−6/°C was measured for copper reinforced with 2 vol% CNT sample at 100 °C. The thermal conductivity of 323 W/mK and 279 W/mK was measured at 100 °C for Cu and Cu-1CNT-0.5 vol%Ru. The X-ray photoelectron spectroscopy was performed on the samples surface in order to determine the effect of additives on the copper surface. XPS revealed that addition of Ru reduced copper oxidation at the surface.
    Synthetic Metals 04/2015; 202. DOI:10.1016/j.synthmet.2015.02.001 · 2.25 Impact Factor
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    • "However, application of the latter has been limited to niche markets due to the high price of diamond particles; moreover, poor machinability of the diamond/metal composites has been an additional limitation [8]. To date, several further carbon-based materials (e.g., carbon fibers [17] [18], carbon nanotubes (CNT) [19] [20] [21] [22], graphite particles [18] [23] [24], porous graphite performs [25] [26], graphite foam [18] [27], graphene [28] [29] etc.) have been considered and integrated in metal matrices via various fabrication techniques. Graphite flakes (G f ), in particular, have attracted significant recent attention for thermal management applications due to their superior thermal properties, low cost and ease of machining [1] [18] [30] [31]. "
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    ABSTRACT: a b s t r a c t Highly thermally conductive graphite flakes (G f)/Si/Al composites have been fabricated using G f , Si pow-der and an AlSi 7 Mg 0.3 alloy by an optimized pressure infiltration process for thermal management appli-cations. In the composites, the layers of G f were spaced apart by Si particles and oriented perpendicular to the pressing direction, which offered the opportunity to tailor the thermal conductivity (TC) and coeffi-cient of thermal expansion (CTE) of the composites. Microstructural characterization revealed that the formation of a clean and tightly-adhered interface at the nanoscale between the side surface of the G f and Al matrix, devoid of a detrimental Al 4 C 3 phase and a reacted amorphous Al–Si–O–C layer, contributed to excellent thermal performance along the alignment direction. With increasing volume fraction of G f from 13.7 to 71.1 vol.%, the longitudinal (i.e. parallel to the graphite layers) TC of the composites increased from 179 to 526 W/m K, while the longitudinal CTE decreased from 12.1 to 7.3 ppm/K (match-ing the values of electronic components). Furthermore, the modified layers-in-parallel model better fitted the longitudinal TC data than the layers-in-parallel model and confirmed that the clean and tightly-adhered interface is favorable for the enhanced longitudinal TC.
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