2.2.2. Cf/Cu
Copper is nonreactive with carbon and the interfacial bonding is weak, resulting in high interfacial resistance and low TC of Cf/Cu composites. In order to improve the interfacial bonding, active elements are added. The addition of 0.5%–0.8% (volume fraction) Ti to Cf/Cu composite results in the formation of TiC on carbon fibers and CuTi2 remains in copper alloy, which significantly improves the interfacial cohesion [17]. However, the TC is only 110–200 W/(m·K) due to the existence of cohesive compounds. A novel sputter processing is applied to deposit interfacial layers and Cu matrix onto continuous carbon fiber in order to enhance bonding between Cu matrix and fiber [18]. It is demonstrated that the TC of Cf/Cu composites is increased to 800 W/(m·K) using the fiber with K=1 100 W/(m·K).