Delicate control of graphite flakes alignment in the copper matrices via powder selections and filling processes

Abstract

Due to the anisotropy properties of graphite flakes (Gf), the control of their orientation inside copper (Cu) matrice is strictly correlated with the final properties of such metal matrix composite (MMC). In this study, MMC’s are fabricated by powder metallurgy process using three types of Cu powder particles (flake, dendritic, and spherical) as well as different powderfilling methods. By using Cu flake powder, with present a relatively lower apparent density as compared to the two other Cu powder types (dendritic, and spherical), high aligned of graphite flakes could be easily obtained, after uniaxial hot pressure, in a one-step powder filling approach. For the other two types of powders, a comparable orientation degree of Gfcould be achieved only via several steps of delicate powder pressing. In-planes thermal conductivity of Cu/Gf composites were enhanced by improving the orientation degree of Gf, agreeing with effective medium approximation predictions. A modeling, based on the apparent density of Cu powders, was discussed to show the effect of the alignment process on the final thermal properties of such MMC’s. This model supplies a basic guideline to obtain highly orientated Gf.

Facile fabrication of layer-structured graphene/copper composite with enhanced electrical and mechanical properties

“…It should be emphasized that the enlarged picture in figure 1(d) shows a good interface bond between the copper substrate and the graphene layer. Since the wettability between graphene and copper is poor, as a bridge between the reinforcement phase and the matrix, this void-free interface is of good electrical conducitivy to reach the excellent comprehensive performance of the composite [28]. Furthermore, figure 1(e) shows the XRD patterns of the pure Cu foil, the Gr coated Cu foil (Cu@Gr), and the Cu/Gr composite.…”