Fabrication, mechanical and thermal properties of tungsten-copper coated graphite flakes reinforced copper matrix composites

Carbon materials reinforced copper matrix composites with excellent mechanical properties, high thermal conductivity (TC) and suitable coefficient of thermal expansion (CTE) are expected to meet the urgent need for the thermal management materials with structural stability and efficient heat dissipation in civil and military fields. In this work, the tungsten-copper (W-Cu) composite coating was deposited on the graphite flakes (GFs) by the impregnation-reduction and ultrasonic-assisted electroless plating. Meanwhile, the W-Cu coated GFs reinforced Cu matrix composites (GFs(W-Cu)/Cu) were also prepared by the vacuum hot-pressing sintering. Based on the microstructure and surface analysis, the interfacial bonding has changed from the simple mechanical connection to the mechanical-metallurgical synergy. As for the three-point bending and uniaxial tensile tests, the largest in-plane, through-plane flexural strength and tensile strength of the GFs(W-Cu)/Cu composite can achieve the values of 189.6 ± 3.8, 172.3 ± 4.2 and 91.9 ± 2.6 MPa, respectively. Among the GFs(W-Cu)/Cu composites, the ultrahigh in-plane TC and lowest through-plane CTE can reach 929.8 ± 5.0 Wm−1K−1 and 6.3 ± 0.2 ppmK−1 respectively, and the better thermal response rate can be 0.67 °C·s−1. In conclusion, an effective way to develop the structural and functional integrated carbon-based thermal management materials can be provided.