Synergistic effects of tungsten coating on the microstructure, thermophysical and mechanical properties of graphite flakes reinforced copper matrix composites

Abstract

With the rapid development of the miniaturization and high-integration of electronic devices, conventional thermal conductive materials cannot ensure the safety and reliability of the high-power devices in working environments. It is urgent to develop thermal management materials with excellent thermophysical and mechanical properties. In this work, the tungsten-coated graphite flakes (GFs(W)) were prepared by the immersion reduction, and the GFs(W) reinforced copper matrix composites (GFs(W)/Cu composites) were prepared by the vacuum hot-pressing sintering. Based on the microstructure and surface analysis, the W coating obtained at 900 °C and 200 g/L AMT appears the excellent surface structure and interfacial adhesion, which transfer the interfacial bonding from mechanical combination to mechanical-metallurgical synergy between the GFs and Cu. In addition, the volume fraction of W coating has a threshold to improve properties of the GFs(W)/Cu composites, in which the GFs(6 W)/Cu composites show the outstanding comprehensive performance: the in-plane thermal conductivity and flexural strength are 879.0 ± 10.0 Wm −1 K −1 and 166.9 ± 3.4 MPa respectively, which are improved by 22.3% and 356.0%, and the lowest coefficient of thermal expansion is 4.3 ± 0.5 ppmK −1 . To sum up, it provides an effective way to develop novel structural and functional integrated graphite/copper composites for thermal management. • A dense W coating was deposited on the graphite flakes by the immersion reduction. • The GFs/Cu interfacial bonding transfers from the mechanical connection into the mechanical-metallurgical synergy. • The in-plane TC of GFs(6 W)/Cu composite is 879.0 ± 10.0 Wm-1 K-1, while the flexural strength up to 166.9±3.4 MPa.