Nanoplatelet Size to Control the Alignment and Thermal Conductivity in Copper–Graphite Composites

Abstract

A controlled alignment of graphite nanoplatelets in a composite matrix will allow developing materials with tailored thermal properties. Achieving a high degree of alignment in a reproducible way, however, remains challenging. Here we demonstrate the alignment of graphite nanoplatelets in copper composites produced via high-energy ball milling and spark plasma sintering. The orientation of the nanoplatelets in the copper matrix is verified by polarized Raman scattering and electron microscopy showing an increasing order with increasing platelet size. The thermal conductivity k along the alignment direction is up to five times higher than perpendicular to it. The composite with the highest degree of alignment has a thermal diffusivity (100 mm(2) s(-1)) comparable to copper (105 mm(2) s(-1)) but is 20% lighter. By modeling the thermal properties of the composites within the effective medium approximation we show that (i) the Kapitza resistance is not a limiting factor for improving the thermal conductivity of a copper-graphite system and (ii) copper-graphite-nanoplatelet composites may be expected to achieve a higher thermal conductivity than copper upon further refinement.

Electrically insulating POE/BN elastomeric composites with high through-plane thermal conductivity fabricated by two-roll milling and hot compression

“…As shown in Fig. 4, the anisotropy factor of thermal conductivity linearly increases with increasing BN concentration (AF = 0.20V f + 1.02), and the same phenomena have been reported for copper/GNPs composites [58]. The significant improvement of thermal conductivity and high value of anisotropy factor (9.62 when the loading of BN is 43.75 vol%) is the result of perfect alignment of BN flakes in the matrix (Fig.…”

Composites of aluminum alloy and magnesium alloy with graphite showing low thermal expansion and high specific thermal conductivity

“…Few copper–graphite samples were prepared for the Brinell hardness measurements (Section 2.4) according to the parameters described by Firkowska et al [12]. The uniaxial pressure during SPS orients the graphite flakes in the composites (see Abstract Figure), giving rise to anisotropic properties [17]. We define the direction parallel to the flakes and perpendicular to the pressing axis as in - plane, the direction parallel to the pressing and perpendicular to the flakes as through - plane.…”

Recently emerging trends in thermal conductivity of polymer nanocomposites

“…However, these nanoparticles require inclusion of about 50-70 vol.% filler to attain thermal conductivity values ranging from 1 to 5 W/m K (Hou et al 2015). Hence, one of the challenges encountered in packaging of semiconductor electronic equipment is the rapid increase in operational power of the devices (Boden et al 2014). Thus, the ability to balance the dimensional reduction of semiconductors with the operational efficiency of these devices has continued to constitute challenges.…”

“…A polymer matrix filled with thermally conducting organic or inorganic fillers with dimensions in nanoscale levels is a nanocomposite suitable for thermal interface applications (Hou et al 2015, Kamseu et al 2015. Thus, PNCs with superior heat dissipation possess great potentials for application in microelectronics as TIMs (Boden et al 2014).…”